Dokument-ID Dokumenttyp Autoren/innen Persönliche Herausgeber/innen Haupttitel Abstract Auflage Verlagsort Verlag Herausgeber (Institution) Erscheinungsjahr Titel des übergeordneten Werkes Jahrgang/Band ISBN Veranstaltung Veranstaltungsort Beginndatum der Veranstaltung Enddatum der Veranstaltung Ausgabe/Heft Erste Seite Letzte Seite URN DOI Lizenz Datum der Freischaltung OPUS4-215 Forschungsbericht Rurack, Knut Steady-State and Time-Resolved Spectroscopy of Ion-Sensitive Fluorescent Probes Im Mittelpunkt der vorliegenden Arbeit stehen Untersuchungen des spektroskopischen und komplexometrischen Verhaltens verschiedener Ionen-sensitiver Fluoreszenzsonden. Drei der vier Sondentypen folgen dabei einem herkömmlichen Prinzip zur Signalerzeugung und entsprechen in ihrem molekularen Aufbau einem fluoreszierenden Liganden (BP(OH)2 ) bzw. sogenannten intrinsischen Ladungstransfer-(ICT)- Fluoreszenzsonden (Donor-Akzeptor-substituierte Chalkone) und Elektronentransfer-(ET)-Fluoreszenzsonden (substituierte Triaryl-Δ2-pyrazoline). Die beiden letzten Systeme sind modular konzipiert, so dass signalgebender Fluorophor und komplexierender Rezeptor gezielt modellierbar sind. Im Fall der ICT-Sonden sind beide Einheiten elektronisch konjugiert, bei den ET-Sonden sind sie dagegen elektronisch weitgehend entkoppelt und das Signal wird durch Beeinflussung eines weitreichenden Elektronentransferprozesses generiert. Die Sonde vierten Typs, ein Bordipyrromethenderivat (BDP), ist ebenfalls modular aufgebaut. Bei ihr sind Fluorophor und Rezeptor aber nur durch den stark vorverdrillten Aufbau des Moleküls „virtuell" entkoppelt. Neben diesem Einsatz eines alternativen Mechanismus zur Signalerzeugung standen vor allem die Steuerung der Selektivität durch gezielte Modifikation des Rezeptors sowie mögliche Verbesserungen der fluorometrischen Metallionenanalytik hinsichtlich Nachweisselektivität und -sensitivität durch Aufnahme zeitaufgelöster Fluoreszenzspektren (TRES) im Vordergrund der Untersuchungen. Unter Zuhilfenahme einer Reihe von Modellsubstanzen, NMR spektroskopischer Messmethoden und quantenchemischer Rechnungen wurden ausserdem allgemeine Erkenntnisse über das lichtinduzierte Verhalten der einzelnen Farbstoffklassen gewonnen. Der fluoreszierende Ligand BP(OH)2 zeigt, analog seiner Mutterverbindung 2,2'-Bipyridyl, komplexierungsinduzierte Änderungen in seinem Absorptions- und Fluoreszenzverhalten bei Anwesenheit von Übergangs- und Schwermetallionen. Während paramagnetische Ionen wie CuII oder NiII (und auch HgII) zur statischen Fluoreszenzlöschung führen, bilden die diamagnetischen Ionen ZnII und CdII stark fluoreszierende Komplexe mit einer ionenspezifischen Fluoreszenzlebensdauer im ns-Zeitbereich. Beide Komplexe sind im angeregten Zustand stabil, was sich u. a. in einer, gegenüber dem freien Liganden stark herabgesetzten Geschwindigkeitskonstante für strahlungslose Desaktivierungsprozesse manifestiert. Die Absorptions- und Emissionsspektren der Komplexe überlappen stark und eine Unterscheidung mittels statischer Spektroskopie ist in beiden Fällen nur sehr begrenzt möglich. Die Trennung beider Komponenten gelingt allerdings unter Einsatz der zeitaufgelösten Fluoreszenzspektroskopie und an mehreren synthetischen ZnII/CdII-haltigen Proben konnte beispielhaft der Gewinn an Selektivität durch Aufnahme der TRES mit anschliessender global- analytischer Auswertung gezeigt werden. Die intrinsischen Fluoreszenzsonden des Chalkontyps tragen den Kationen-selektiven Rezeptor im Donorteil des Moleküls und zeigen bei Komplexierung durch Schwächung des Donors eine starke Abnahme des intramolekularen Ladungstransferprozesses. Im unkomplexierten Zustand erfolgt Fluoreszenz, je nach molekularem Aufbau und Polarität des Lösungsmittels, aus einem polaren direkt angeregten (E*) oder unter Einfachbindungsverdrillung und Reaktion im angeregten Zustand besetzten, hochpolaren Ladungstransferzustand (A*). Als konkurrierende Prozesse spielen dabei mögliche Besetzungen eines nicht fluoreszierenden, polaren (K*) bzw. schwach polaren (P*) Übergangszustandes eine Rolle. Des Weiteren ist in diesem Farbstoffsystem die Möglichkeit der Fluoreszenzlöschung durch benachbarte, tiefliegende nπ* Zustände (in unpolaren Lösungsmitteln) sowie durch verstärkte interne Konversion aufgrund des geringen energetischen Abstandes von Grund und angeregtem Zustand (in hochpolaren Lösungsmitteln) gegeben. Bei Kationenkomplexierung in polaren Lösungsmitteln wird vor allem, wie oben angedeutet, der Donor abgeschwächt, und es kommt zu einer moderaten Fluoreszenzverstärkung. Neben der erhöhten Fluoreszenzquantenausbeute resultiert der Effekt in Ionen-spezifischen Fluoreszenzlebensdauern der Komplexe. Durch den Austausch eines Stickstoff-Sauerstoff- gegen einen Stickstoff-Schwefel-Makrozyklus im Rezeptorteil des Systems konnte die Ionenselektivität von den Alkali- und Erdalkalimetallionen zu den thiophilen Metallionen AgI und HgII umgeleitet werden, wobei insbesondere die Fluoreszenzverstärkung in Gegenwart des herkömmlich als Fluoreszenzlöscher bekannten HgII-Ions analytisch wertvoll ist. Die ET-Sonden des Triaryl-Δ2-pyrazolin-Typs zeigen gegenüber den ICT-Sonden nur geringe spektrale Effekte, die Ioneninduzierte Fluoreszenzverstärkung ist dagegen wesentlich größer. Durch den gezielten Einsatz der unterschiedlichen Rezeptoren lassen sich hier ebenfalls die Selektivitäten steuern. In vergleichenden Untersuchungen konnten für die 5-p-N,NDialkylanilino-3-benzthiazol-1-phenyl-Δ2-pyrazoline die intramolekularen Prozesse charakterisiert werden, die Fluoreszenzlöschung im unkomplexierten und ein „Anschalten" der Fluoreszenz im gebundenen Zustand bewirken. In diesen Molekülen findet der intramolekulare Ladungstransfer im Hauptchromophor im sub-ps Bereich statt und wird in hochpolaren Lösungsmitteln durch einen Elektronentransferprozess auf der ps-Zeitskala vom weitgehend elektronisch entkoppelten Rezeptor zum Akzeptorteil des Hauptchromophors gelöscht. Die „virtuelle" Entkopplung von Fluorophor und Rezeptor im BDP-Derivat ermöglicht schließlich die Erzeugung von sehr grossen Fluoreszenzverstärkungssignalen bei Komplexierung. In diesen stark vorverdrillten Donor- Akzeptor-Biarylen geht der direkt angeregte emittierende Zustand (LE) in polaren Lösungsmitteln in einen hochpolaren, verdrillten radikalionischen Ladungstransferzustand (CT) über. Emission aus letzterem ist stark verboten und erfolgt, je nach Lösungsmittelpolarität, (weit) rotverschoben zur Fluoreszenz des LE, so dass schon in mittelpolaren Lösungsmitteln eine weithin getrennte, duale Fluoreszenz zu beobachten ist. In hochpolaren Lösungsmitteln sind beide Fluoreszenzen nahezu vollständig gelöscht. Metallionenkomplexierung führt zur Unterbrechung des CT-Prozesses und somit zu einem „Anschalten" der LE- Emission mit Fluoreszenzverstärkungsfaktoren > 1000. Dieser Prozess ist dabei so sensitiv, dass für die meisten Kationenkomplexe zwei spektral sehr stark überlappend absorbierende und emittierende Komplexkonformere anhand ihrer Fluoreszenzlebensddauer unterschieden werden können. Bremerhaven Wirtschaftsverlag NW Bundesanstalt für Materialforschung und -prüfung (BAM) 2009 235 978-3-89701-362-2 1 136 urn:nbn:de:kobv:b43-2150 http://www.gesetze-im-internet.de/urhg/index.html 2015-01-23 OPUS4-227 Forschungsbericht Rurack, Knut; Resch-Genger, Ute Design, Synthese und Charakterisierung von Fluoreszenzstandards und Fluoreszenzmarkern für die zeitaufgelöste Fluorometrie Im Rahmen dieses Projekts wurden Fluoreszenzfarbstoffe und neue intrinsische und konjugierte Fluoreszenzmarker mit Sauerstoff, Schwefel, Stickstoff-Heteromakrozyklen als kationenspezifische Rezeptoren für analytische Applikationen der zeitaufgelösten Fluorometrie von der Kiewer Gruppe synthetisiert. Die in Berlin an diesen Verbindungen durchgeführten fluorometrischen Charakterisierungen und spektroskopischen Untersuchungen zum Kationenkomplexierungsverfahren ermöglichten die Aufstellung von ersten Designprinzipien für Fluoreszenzmarker für Übergangs- und Schwermetallionen. Bremerhaven Wirtschaftsverlag NW Bundesanstalt für Materialforschung und -prüfung (BAM) 1998 223 978-3-89701-038-0 1 40 urn:nbn:de:kobv:b43-2273 http://www.gesetze-im-internet.de/urhg/index.html 2015-06-18 OPUS4-968 Zeitschriftenartikel Rurack, Knut; Radeglia, Reiner Transition Metal Ion Complexes of 2,2'-Bipyridyl-3,3'-diol and 2,2'-Bipyridyl-3-ol: Spectroscopic Properties and Solvent-Dependent Binding Modes The complexation behaviour of 2,2-bipyridyl-3,3-diol and 2,2-bipyridyl-3-ol, BP(OH)2 and BPOH, with various heavy and transition metal ions has been investigated in aqueous, alcoholic, and acetonitrile solutions. Whereas the complexes with paramagnetic ions and HgII are non-fluorescent, ZnII and CdII form highly fluorescent complexes, their coordination geometries depending on the solvent proticity and hydrogen-bond donating ability. Through a comparative study with the corresponding chelates of 2,2-bipyridyl (bipy), N,O-coordination in a six-membered ring chelate has been found to be the dominant binding mode in both the ZnII and CdII complexes in the protic solvents water and ethanol. Only for ZnII and BPOH is exclusive N,N-chelation found in acetonitrile. NMR measurements on BP(OH)2, BPOH, and bipy in the presence of ZnII and CdII in acetonitrile confirmed these findings. Weinheim Wiley-VCH Verl. 2000 European journal of inorganic chemistry 2000 10 2271 2282 10.1002/1099-0682(200010)2000:10<2271::AID-EJIC2271>3.0.CO;2-3 2016-02-19 OPUS4-969 Zeitschriftenartikel Rurack, Knut; Maus, M. Monitoring pH and solvent proticity with donor-acceptor-substituted biphenyls: a new approach towards highly sensitive and powerful fluorescent probes by tuning the molecular structure The ability and structural requirements of 4-dimethylamino-4-cyano-substituted biphenyls showing photoinduced intramolecular charge transfer (CT) to serve as hydrogen bond- or pH-sensitive fluorescent probes is investigated. The donor–acceptor (D–A) biphenyls I and II being planar in the CT excited state are most suitable as pH-sensitive fluorescent probes. The two compounds show analytically valuable features such as well-separated absorption and emission bands and signal changes spanning four orders of magnitude and can be employed in ratiometric, self-calibrating, and highly sensitive pH fluorosensing in the range 0103. This efficient "switching on" of the fluorescence renders the crowned BDP dye an extremely sensitive fluorescent probe for metal ions. Washington, DC Soc. American Chemical Society 1998 The journal of physical chemistry / A 102 50 10211 10220 10.1021/jp982701c 2016-02-19 OPUS4-2096 Zeitschriftenartikel Rurack, Knut; Resch-Genger, Ute; Rettig, W. Global analysis of time-resolved emission-a powerful tool for the analytical discrimination of chemically similar ZnII and CdII complexes The simultaneous analytical discrimination of spectrally very similar components with time- and wavelength-resolved fluorescence spectroscopy is demonstrated for the fluorescent probe BP(OH)2 and its complexes with the d10 metal ions CdII and ZnII in water. Whereas the absorption and emission spectra of the three components largely overlap the fluorescence lifetimes differ significantly. As a consequence, analyzing steady-state emission spectra of samples containing unknown amounts of both metal ions yields poor results for the analytical validity but the recording of fluorescence decay curves at different emission wavelengths improves the quality of the results drastically. The two techniques are compared in terms of goodness and analytical accuracy of the fit as well as analytical applicability. Lausanne Elsevier 1998 Journal of photochemistry and photobiology / A 118 3 143 149 10.1016/S1010-6030(98)00369-4 2016-02-19 OPUS4-2097 Beitrag zu einem Sammelband Rurack, Knut; Bricks, J. L.; Slominskii, J. L.; Resch-Genger, Ute Dähne, S. Long wavelength emitting fluorescence probes for metal ions Dordrecht Kluwer 1998 Near-infrared dyes for high technology applications (NATO ASI series : Partnership sub-series 3, High technology v. 52) NATO Advanced Research Workshop on Syntheses, Optical Properties and Applications of Near-Infrared (NIR) Dyes in High Technology Fields Trest', Czech Republic 1997-09-24 1997-09-27 52 191 200 2016-02-19 OPUS4-2098 Zeitschriftenartikel Rurack, Knut; Bricks, J.L.; Slominskii, J.L.; Resch-Genger, Ute Cation complexing fluorescence probes containing the benz[c,d]indole fluorophore Kidlington Elsevier Science 1998 Dyes and pigments 36 2 121 138 2016-02-19 OPUS4-2099 Beitrag zu einem Sammelband Resch-Genger, Ute; Rurack, Knut Lieberman, R. Steady-state and time-resolved fluorometry of fluorescent pollutants and heavy metal complexes Time-resolved laser-induced fluorescence spectroscopy is one of the most sensitive optical methods which is well suited for on-line in situ analysis. Here, three examples for the steady- state and time-resolved fluorescence analysis of environmentally important analytes, the fluorescent monoaromatic hydrocarbons benzene, toluene, and xylene as well as non fluorescent heavy metal ions forming a fluorescent complex with a cation coordinating fluorescence probe, are presented and the potential of both methods is discussed. For BTX, various mixtures of the spectrally similar compounds B, T, and X showing different fluorescence lifetimes were studied with both methods. As an example for fluorometric metal ion analysis, the fluorescence probe BP(OH)2 (2,2'-bipyridyl- 3,3'-diol) was employed for the determination of d10 metal ions in water and the newly developed fluorescence probe APTA for the detection of Cu(II). Cation complexation of BP(OH2 yields spectrally very similar complexes which differ in their fluorescence lifetimes. Complexation of APTA to Cu(II) leads to small spectral changes and a strong increase in fluorescence quantum yield and lifetime. For the analytes studied, a comparison of the detection limits, standard deviations, and linear dynamic range of both methods clearly demonstrates the analytical potential of time-resolved fluorometry. Bellingham, Wash. SPIE Deutsche Forschungsanstalt für Luft- und Raumfahrt, Köln 1997 Chemical, biochemical, and environmental fiber sensors IX 0-8194-2526-5 Conference Munich, Germany 1997-06-16 1997-06-18 3105 96 103 10.1117/12.276139 2016-02-19 OPUS4-2100 Zeitschriftenartikel Resch-Genger, Ute; Rurack, Knut; Bricks, J.L.; Slominskii, J.L. New fluorophore receptor systems for heavy metal ions: a spectroscopic study New York, NY Plenum Publ. Corp. 1997 Journal of fluorescence 7 1 231S 233S 2016-02-19 OPUS4-2101 Zeitschriftenartikel Rurack, Knut; Bricks, J.L.; Kachkovski, A.; Resch-Genger, Ute Complexing fluorescence probes consisting of various fluorophores linked to 1-aza-15-Crown-5 New York, NY Plenum Publ. Corp. 1997 Journal of fluorescence 7 1 63S 66S 2016-02-19 OPUS4-2102 misc Rurack, Knut; Resch-Genger, Ute; Rettig, W. ZnII and CdII complexes of 2,2'-bipyridyl-3,3'-diol: discrimination with time-resolved fluorometry Berlin Berliner Elektronenspeicherring-Gesellschaft für Synchrotronstrahlung 1996 BESSY Jahresbericht 1995 459 460 2016-02-19 OPUS4-2103 Zeitschriftenartikel Rurack, Knut; Senoner, Mathias; Resch-Genger, Ute; Dähne, Siegfried Heavy metal complexes of 2,2'-bipyridyl-3,3'-diol Berlin Akad. Verl. 1994 Journal of information recording materials = Journal für Signalaufzeichnungsmaterialien 21 683 684 2016-02-19 OPUS4-2104 Zeitschriftenartikel Resch-Genger, Ute; Rurack, Knut; Senoner, Mathias Zeitaufgelöste Fluorometrie in der Wasseranalytik Weinheim Wiley-VCH Verl. 1994 Nachrichten aus Chemie, Technik und Laboratorium 42 5 504 506 2016-02-19 OPUS4-2105 Zeitschriftenartikel Rurack, Knut; Resch-Genger, Ute; Senoner, Mathias; Dähne, Siegfried A new fluorescence probe for trace metal ions: cation dependent spectroscopic properties New York, NY Plenum Publ. Corp. 1993 Journal of fluorescence 3 3 141 143 2016-02-19 OPUS4-2106 Zeitschriftenartikel Rurack, Knut; Bricks, J. L.; Reck, Günter; Schulz, Burkhard; Spieles, Monika Cation coordination of bisamidopyridine-derived receptors as investigated in the solid-state and in solution A bisamidopyridine-type receptor, N,N'-bis(6-methyl-2-pyridyl)pyridine-2,6-dicarboxamide (1), and its CoIII complex were prepared and their X-ray structures were compared to those of N,N'-diphenylpyridine-2,6-dicarboxamide (2) and CoIII(2)2. Introduction of the two additional coordinative groups resulted in second-order interactions between the central ion and the nitrogen atoms of the terminal pyridine moieties in the crystalline state. Solution studies in acetonitrile revealed the importance of these interactions for the ligand's metal ion recognition ability. Whereas 2 only binds to PbII and CuII, 1 yields complexes with a majority of the heavy and transition metal ions studied, CoII, NiII, CuII, ZnII, FeIII, FeII, HgII, and PbII, respectively. The cation binding properties in solution were investigated by absorption spectroscopy and in the case of 1-MII/III, the formation of two spectroscopically distinguishable types of complexes was found. Protonation experiments and theoretical considerations helped to gain further insight into possible modes of coordination in solution. New York, NY Gordon and Breach Science Publ. 2003 Supramolecular chemistry 15 3 189 197 10.1080/1061027031000078239 2016-02-19 OPUS4-2107 Zeitschriftenartikel Rurack, Knut; Danel, A.; Rotkiewicz, K.; Grabka, D.; Spieles, Monika; Rettig, W. 1,3-Diphenyl-1H-pyrazolo[3,4-b]quinoline - A Versatile Fluorophore for the Design of Brightly Emissive Molecular Sensors The 1,3-diphenyl-1H-pyrazolo[3,4-b]-quinoline chromophore is a versatile building block for the construction of brightly fluorescent molecular sensors. Facile synthetic procedures allow integration of the chromophore into fluorophore-spacer-receptor systems as well as fluoroionophores operating via intramolecular charge transfer. Whereas the former photoinduced electron-transfer probes show strong analyte-induced fluorescence enhancement, the latter exhibit bright ratiometric dual emission. Employing prototype macrocyclic receptors, the favorable signaling features for metal ion recognition are demonstrated. Washington, DC American Chemical Society 2002 Organic letters 4 26 4647 4650 10.1021/ol027025i 2016-02-19 OPUS4-2108 Zeitschriftenartikel Fery-Forgues, S.; Rurack, Knut; Delavaux-Nicot, B.; Lavabre, D. 1,3-Diphenyl-1H-pyrazolo[3,4-b]-quinoline (DPPQ)-a versatile fluorophore for the design of brightly emissive molecular sensors Lausanne Elsevier 2002 Journal of photochemistry and photobiology / A 2016-02-19 OPUS4-1085 Zeitschriftenartikel Rurack, Knut; Kollmannsberger, M.; Daub, J. A highly efficient sensor molecule emitting in the near infrared (NIR): 3,5-distyryl-8-(p-dimethylaminophenyl)-difluoroboradiaza-s-indacene The spectroscopic properties and the photophysical behaviour of difluoroboradiaza-s-indacene 1, especially designed for the near infrared (NIR) spectral region and equipped with a p-dimethylaminophenyl group at the meso-position, were studied by steady-state and time-resolved optical spectroscopy. Solvent-dependent measurements revealed that for 1, excited state deactivation is governed by population of a non-emissive charge transfer excited state (1CT) as the solvent polarity increases, whereas reference compound 2 shows strong fluorescence from a locally excited state (1LE) in all the solvents employed. Accordingly, protonation of 1 completely suppresses the quenching excited state charge transfer process and leads to strong enhancement of fluorescence in the NIR, distinguishing 1 as a very sensitive fluorescent sensor molecule for pH or solvent acidity in this favourable wavelength region. Paris Le Centre National de la Recherche Scientifique 2001 New journal of chemistry = Nouveau journal de chimie 25 289 292 10.1039/b007379m 2016-02-19 OPUS4-1077 Zeitschriftenartikel Rurack, Knut; Kollmannsberger, M.; Daub, J. Molekulares Schalten im nahen Infrarot (NIR) mit einem funktionalisierten Bordipyrromethen-Farbstoff Weinheim Wiley-VCH Gesellschaft Deutscher Chemiker 2001 Angewandte Chemie 113 2 396 399 10.1002/1521-3757(20010119)113:2<396::AID-ANGE396>3.0.CO;2-W 2016-02-19 OPUS4-1078 Zeitschriftenartikel Rurack, Knut; Kollmannsberger, M.; Daub, J. Molecular Switching in the Near Infrared (NIR) with a Functionalized Boron-Dipyrromethene Dye Weinheim Wiley-VCH Gesellschaft Deutscher Chemiker 2001 Angewandte Chemie / International Edition 40 2 385 387 10.1002/1521-3773(20010119)40:2<385::AID-ANIE385>3.0.CO;2-F 2016-02-19 OPUS4-1080 Zeitschriftenartikel Unger, Brita; Rurack, Knut; Müller, Ralf; Resch-Genger, Ute; Buttke, K. Effects of the Sol-Gel Processing on the Fluorescence Properties of Laser Dyes in Tetraethoxysilane Derived Matrices Two fluorescent dyes were incorporated into sol-gel derived SiO2 matrices. The dye was added to SiO2 precursors of different degrees of pre-condensation and the spectroscopic properties of the immobilized dye were measured at various aging and drying stages of the resulting gels. The significant influence of the processing parameters on the spectroscopic properties is manifested in the relative intensity of a second red shifted emission band (550–560 nm), which was observed besides the typical coumarin emission band (495 nm). The appearance of this long wavelength emission might be attributed to dye aggregation or to other reactions with the ambient matrix forced by micro porosity phenomena. Dordrecht Kluwer Academic Publ. 2000 Journal of sol gel science and technology 19 799 802 10.1023/A:1008768318418 2016-02-19 OPUS4-2377 Zeitschriftenartikel Descalzo, Ana B.; Martínez-Mánez, Ramon; Radeglia, Reiner; Rurack, Knut; Soto, J. Coupling Selectivity with Sensitivity in an Integrated Chemosensor Framework: Design of a Hg2+-Responsive Probe, Operating above 500 nm For the highly selective and sensitive sensing of Hg2+ in water, a new design concept was realized where the selectivity of the probe's binding site is amplified by electronic properties of the chromophore. The molecular architecture of this phenoxazinone-type sensor molecule combines two potential coordination sites via an amino-keto conjugative backbone. These structural prerequisites allow only the most preferred mercuric ion to bind to the dithia dioxa monoaza crown unit, while other heavy, transition, and main group metal ions as well as protons are trapped at the keto group, inducing opposite spectral effects due to interaction with either the donor (Hg2+) or the acceptor group (other cations) of the probe. Besides these advantageous features, the probe operates well within the visible range of the spectrum and displays rather intense molar absorptivities as well as fluorescence quantum yields. Washington, DC American Chemical Society 2003 Journal of the American chemical society 125 12 3418 3419 10.1021/ja0290779 2016-02-19 OPUS4-7427 Posterpräsentation Rurack, Knut A Chromo- and Fluorogenic Hybrid Chemosensor Material for the Detection of Long-chain Carboxylates 2005 ANAKON 2005 ANAKON 2005 Regensburg, Germany 2005-03-15 2005-03-18 2016-02-19 OPUS4-7428 Posterpräsentation Rurack, Knut A hybrid chemosensor material for the colorimetric and fluorometric detection of long-chain carboxylates 2005 9th Conference on Methods and Applications of Fluorescence: Spectroscopy, Imaging and Probes 9th Conference on Methods and Applications of Fluorescence: Spectroscopy, Imaging and Probes Lisbon, Portugal 2005-09-04 2005-09-07 2016-02-19 OPUS4-10378 Zeitschriftenartikel Unger, Brita; Rurack, Knut; Müller, Ralf; Jancke, Harald; Resch-Genger, Ute Microscopic vs. macroscopic structural evolution of SiO2 sols and gels employing a tailor-made fluorescent reporter dye The short- and long-term structural evolution and aging of sol–gel materials prepared under mild conditions are studied by fluorometry, dynamic light scattering (DLS), 29Si NMR and gravimetry. In combination with the first, a newly developed donor–acceptor-substituted fluorescent probe with two acidophilic sites of different strength and topology is introduced. Its performance in detecting changes in parameters such as polarity, proticity, and pore volume on the microscopic scale is compared to two other dyes and to the macroscopic changes revealed by DLS, NMR and gravimetry. At early stages of the sol–gel process, fluorometry, DLS and NMR reveal similar changes which are typical of the structural evolution of SiO2 sols having different synthesis parameters. During later times of sol aging, DLS and NMR reflect the growth of the network and indicate that all sols approach similar structural equilibria. Fluorometry supports these findings by signalling a gradual decrease in mobile species with high proton activity. The formation of the spanning cluster upon gelation is strongly evident only from DLS results while the local environment of the fluorophore remains largely unchanged. However, the fluorescent dye is able to report microscopic changes even during long-term aging. Drying of the gels with a pronounced contraction of solvated pores is readily observable by fluorometry and gravimetry. During the late reaction stages, the fluorescence properties of the tailor-made dye are still sensitive toward the environment. Cambridge Royal Society of Chemistry 2005 Journal of materials chemistry 15 30 3069 3083 10.1039/b501622c 2016-02-19 OPUS4-10379 Zeitschriftenartikel Ros-Lis, J.V.; Marcos, M. Dolores; Martínez-Mánez, Ramon; Rurack, Knut; Soto, J. Ein regeneratives Chemodosimeter für die hoch selektive und empfindliche optische Bestimmung von Hg2+, basierend auf der metallinduzierten Bildung eines Farbstoffes Weinheim Wiley-VCH Gesellschaft Deutscher Chemiker 2005 Angewandte Chemie 117 28 4479 4482 2016-02-19 OPUS4-11068 Zeitschriftenartikel Lutz, J.-F.; Thünemann, Andreas; Rurack, Knut DNA-like "Melting" of Adenine- and Thymine-Functionalized Synthetic Copolymers Washington, DC American Chemical Society 2005 Macromolecules 38 20 8124 8126 2016-02-19 OPUS4-10824 Zeitschriftenartikel Resch-Genger, Ute; Pfeifer, Dietmar; Monte, Christian; Pilz, Walter; Hoffmann, Angelika; Spieles, Monika; Rurack, Knut; Hollandt, J.; Taubert, D.; Schönenberger, B.; Nording, P. Traceability in Fluorometry: Part II. Spectral Fluorescence Standards The need for the traceable characterization of fluorescence instruments is emphasized from a chemist’s point of view, focusing on spectral fluorescence standards for the determination of the wavelength- and polarization-dependent relative spectral responsivity and relative spectral irradiance of fluorescence measuring systems, respectively. In a first step, major sources of error of fluorescence measurements and instrument calibration are revealed to underline the importance of this issue and to illustrate advantages and disadvantages of physical and chemical transfer standards for generation of spectral correction curves. Secondly, examples for sets of traceable chemical emission and excitation standards are shown that cover a broad spectral region and simple procedures for the determination of corrected emission spectra with acceptable uncertainties are presented. With proper consideration of the respective measurement principle and geometry, these dye-based characterization procedures can be not only applied to spectrofluorometers but also to other types of fluorescence measuring systems and even to Raman spectrometers. New York, NY Plenum Publ. Corp. 2005 Journal of fluorescence 15 3 315 336 10.1007/s10895-005-2629-9 2016-02-19 OPUS4-12561 Zeitschriftenartikel Yu, Y.-H.; Descalzo López, Ana Belén; Sgen, Z.; Röhr, Holger; Liu, Q.; Wang, Y.-W.; Spieles, Monika; Li, Y.-Z.; Rurack, Knut; You, X.-Z. Mono- and Di(dimethylamino)styryl-Substituted Borondipyrromethene and Borondiindomethene Dyes with Intense Near-Infrared Fluorescence Four novel borondipyrromethene (BDP) and -diindomethene (BDI) dyes with one or two (dimethylamino)styryl extensions at the chromophore were synthesized and spectroscopically investigated. An X-ray crystal structure shows that the extended auxochrome is virtually planar. All dyes thus display intense red/near infrared (NIR) absorption and emission. The (dimethylamino)styryl group induces a charge-transfer character that entails bright solvatochromic fluorescence, which is only quenched with increasing solvent polarity according to the energy-gap law. The dye with an additional dimethylanilino group at the meso position of BDP shows a remarkable switching of lipophilicity by protonation. Two dyes with an 8-hydroxyquinoline ligand at the meso position display quenched emission in the presence of Hg2+ or Al3+ owing to electron transfer from the excited BDP to the complexed receptor. The BDI dye presents a pH indicator with bright fluorescence and extremely low fluorescence anisotropy. Weinheim Wiley-VCH Verl. 2006 Chemistry / Asian Journal 1 1-2 176 187 10.1002/asia.200600042 2016-02-19 OPUS4-12563 Zeitschriftenartikel García-Acosta, B.; Comes, M.; Bricks, J.L.; Kudinova, M.A.; Kurdyukov, V.V.; Tolmachev, A.I.; Descalzo López, Ana Belén; Marcos, M. Dolores; Martínez-Mánez, Ramon; Moreno, A.; Sancenón, F.; Soto, J.; Villaescusa, L.A.; Rurack, Knut; Barat, J. M.; Escriche, I.; Amorós, P. Sensory hybrid host materials for the selective chromo-fluorogenic detection of biogenic amines Cambridge Royal Society of Chemistry Chemical Society 2006 Chemical communications 21 2239 2241 2016-02-19 OPUS4-7282 Zeitschriftenartikel Ros Lis, J.V.; Martínez-Mánez, Ramon; Rurack, Knut; Soto, J. A regenerative chemodosimeter based on metal-induced dye formation for the highly selective and sensitive optical detection of Hg2+ Weinheim Wiley-VCH Gesellschaft Deutscher Chemiker 2005 Angewandte Chemie 117 4479 4482 10.1002/ange.200500583 2016-02-19 OPUS4-5353 Posterpräsentation Rurack, Knut Novel Modular Sensors: Design of Efficient Probes for Various Analytes Utilizing the Phenoxazinone Chromophore 2004 Tag der Chemie Tag der Chemie Potsdam, Germany 2004-07-07 2016-02-19 OPUS4-5985 Zeitschriftenartikel Descalzo López, Ana Belén; Rurack, Knut; Weißhoff, Hardy; Martínez-Mánez, Ramon; Marcos, M. Dolores; Amorós, P.; Hoffmann, Katrin; Soto, J. Rational Design of a Chromo- and Fluorogenic Hybrid Chemosensor Material for the Detection of Long-Chain Carboxylates A strategy for the rational design of a new optical sensor material for the selective recognition of long-chain carboxylates in water is presented. The approach relies on the combination of structure-property relationships to single out the optimal molecular sensor unit and the tuning of the sensing characteristics of an inorganic support material. A spacer-substituted 7-urea-phenoxazin-3-one was employed as the signaling moiety and a mesoporous trimethylsilylated UVM-7 (MCM-41 type) material served as the solid support. The sensor material shows the advantageous features of both modules that is absorption and emission in the visible spectral range, a fluorescence red-shift and enhancement upon analyte coordination, and the amplification of noncovalent (binding) and hydrogen-bonding (recognition) interactions in the detection event. Besides these basic results that are related to the design and performance of the sensor material, the paper discusses general aspects of amido-substituted phenoxazinone photophysics and addresses some general features of molecular anion recognition chemistry in aqueous vs nonaqueous media, utilizing steady-state and time-resolved optical as well as NMR spectroscopies. Detailed studies on potentially competing biochemical species and a first access to the schematic model of the response of the sensor material as obtained by a combination of fluorescence lifetime distribution analysis and Langmuir-type fitting of the gross binding constants complement the key issues of the paper. Washington, DC American Chemical Society 2005 Journal of the American chemical society 127 184 200 10.1021/ja045683n 2016-02-19 OPUS4-11006 Zeitschriftenartikel Ros Lis, J.V.; Martínez-Mánez, Ramon; Rurack, Knut; Soto, J. A regenerative chemodosimeter based on metal-induced dye formation for the highly selective and sensitive optical detection of Hg2+ Weinheim Wiley-VCH Gesellschaft Deutscher Chemiker 2005 Angewandte Chemie / International Edition 44 4405 4407 10.1002/anie.200500583 2016-02-19 OPUS4-28739 Zeitschriftenartikel Wan, Wei; Biyikal, Mustafa; Wagner, R.; Sellergren, B.; Rurack, Knut Sensorische Mikropartikel aus einem Silicatkern und einem molekular geprägten Polymer als Schale mit aufleuchtender Fluoreszenz Und es ward Licht - der Einbau eines auf Harnstoff basierenden Fluoreszenzfarbstoffs in eine mit Anionen geprägte dünne Polymerschale (MIP) auf Silicatmikropartikeln führt zu einem spezifischen und enantioselektiven Aufleuchten der Fluoreszenz in Gegenwart des Zielanalyten. Weinheim Wiley-VCH Gesellschaft Deutscher Chemiker 2013 Angewandte Chemie 125 27 7161 7165 10.1002/ange.201300322 2016-02-20 OPUS4-28740 Zeitschriftenartikel Wan, Wei; Biyikal, Mustafa; Wagner, R.; Sellergren, B.; Rurack, Knut Fluorescent sensorymicroparticles that 'light-up' consisting of a silica core and a molecularly imprinted polymer (MIP) shell From darkness came light: Incorporation of urea-based fluorescent dyes in an anion-imprinted thin polymer shell coated onto silica microparticles leads to a unique and highly enantioselective fluorescent 'light-up' response to analytes (see scheme, MIP molecularly imprinted polymer). Weinheim Wiley-VCH Gesellschaft Deutscher Chemiker 2013 Angewandte Chemie / International Edition 52 27 7023 7027 10.1002/anie.201300322 2016-02-20 OPUS4-28660 Zeitschriftenartikel Zhu, Shengchao; Panne, Ulrich; Rurack, Knut A rapid method for the assessment of the surface group density of carboxylic acid-functionalized polystyrene microparticles Particle-based assays are becoming versatile analytical tools due to their cost-effectiveness, speed, straightforward and diverse functionalization chemistries, especially when polystyrene particles are used. The introduction of functional groups (-COOH, -NH2, etc.) to the surface of such polystyrene particles promotes their application in bioanalytics. However, the traditional method to determine the amount of surface carboxylate groups is conductivity titration, which is usually time- and resources-consuming and discontinuous. Here, we synthesized polystyrene microparticles with different contents of carboxylate groups, and then investigated a simpler and potentially continuous approach to determine the amount of surface carboxylate groups by Zeta potential measurements. The results were compared to the traditional titration method and to actual coupling efficiencies of the functionalized particles with a model oligonucleotide probe as determined by flow cytometry. All quantification methods revealed good agreement. Cambridge Royal Society of Chemistry 2013 Analyst 138 10 2924 2930 10.1039/c3an36578f 2016-02-20 OPUS4-24352 Zeitschriftenartikel Martínez-Mánez, Ramon; Sancenón, F.; Biyikal, Mustafa; Hecht, Mandy; Rurack, Knut Mimicking tricks from nature with sensory organic-inorganic hybrid materials Design strategies for (bio)chemical systems that are inspired by nature's accomplishments in system design and operation on various levels of complexity are increasingly gaining in importance. Within the broad field of biomimetic chemistry, this article highlights various attempts toward improved and sophisticated sensory materials that rely on the combination of supramolecular (bio)chemical recognition principles and nanoscopic solid structures. Examples range from more established concepts such as hybrid sensing ensembles with improved sensitivity and selectivity or for target analytes for which selectivity is hard to achieve by conventional methods, which were often inspired by protein binding pockets or ion channels in membranes, to very recent approaches relying on target-gated amplified signalling with functionalised mesoporous inorganic supports and the integration of native biological sensory species such as transmembrane proteins in spherically supported bilayer membranes. Besides obvious mimicry of recognition-based processes, selected approaches toward chemical transduction junctions utilizing artificially organized synapses, hybrid ensembles for improved antibody generation and uniquely colour changing systems are discussed. All of these strategies open up exciting new prospects for the development of sensing concepts and sensory devices at the interface of nanotechnology, smart materials and supramolecular (bio)chemistry. Cambridge Royal Society of Chemistry 2011 Journal of materials chemistry 21 34 12588 12604 10.1039/c1jm11210d 2016-02-19 OPUS4-24489 Zeitschriftenartikel Calero, P.; Hecht, Mandy; Martínez-Mánez, Ramon; Sancenón, F.; Soto, J.; Vivancos, J.L.; Rurack, Knut Silica nanoparticles functionalised with cation coordination sites and fluorophores for the differential sensing of anions in a quencher displacement assay (QDA) In conjunction with quenching metal ions, silica nanoparticles carrying terpyridine coordination sites and sulforhodamine B signalling units were employed for the differential fluorometric recognition of anions. Cambridge Royal Society of Chemistry Chemical Society 2011 Chemical communications 47 38 10599 10601 10.1039/c1cc13039k 2016-02-19 OPUS4-27488 Zeitschriftenartikel Xu, H.-J.; Mack, J.; Wu, D.; Xue, Z.-L.; Descalzo López, Ana Belén; Rurack, Knut; Kobayashi, N.; Shen, Z. Synthesis and properties of fused-ring-expanded porphyrins that were core-modified with group 16 heteroatoms The synthesis of a series of novel core-modified and fused-ring-expanded tetraphenylporphyrins is reported. Theoretical calculations and magnetic circular dichroism (MCD) and fluorescence spectroscopic measurements were used to analyze the effect of core modification with Group 16 oxygen, sulfur, selenium, and tellurium atoms on the optical properties and electronic structures of the porphyrins. Marked redshifts of the Q and B bands and accelerated intersystem-crossing rates were observed, thus making these compounds potentially suitable for use in a variety of applications. The scope for further fine-tuning of these optical properties based on additional structural modifications, such as the incorporation of fused benzene rings to form ABAB structures by using a thiophene precursor with a fused bicyclo[2.2.2]octadiene ring and the introduction of various substituents onto the meso-phenyl rings, is also examined. Weinheim Wiley-VCH Verl. 2012 Chemistry - A European journal 18 52 16844 16867 10.1002/chem.201200956 2016-02-20 OPUS4-27638 Zeitschriftenartikel Hecht, Mandy; Kraus, Werner; Rurack, Knut A highly fluorescent pH sensing membrane for the alkaline pH range incorporating a BODIPY dye A robust and re-usable dipstick-type fluorescent pH sensor for the alkaline pH range was developed by embedding a brightly fluorescent boron–dipyrromethene (BODIPY) dye bearing an acidic phenol moiety into a polyurethane matrix immobilized on a 3D epoxy-functionalized polymer support. The sensor strip has a dynamic working range of pH 10.0-13.1, i.e., operates in strongly basic media where pH glass electrodes can suffer from alkaline errors, and tolerates a high electrolyte background such as simulated seawater and sewage. This work describes the preparation of the sensing material and provides insight into the features that a hydrogel sensing membrane can bestow on an embedded pH-responsive dye by means of optical spectroscopic investigations. Cambridge Royal Society of Chemistry 2013 Analyst 138 1 325 332 10.1039/c2an35860c 2016-02-20 OPUS4-27741 Zeitschriftenartikel Wagner, R.; Wan, Wei; Biyikal, Mustafa; Benito-Pena, E.; Moreno-Bondi, M.C.; Lazraq, I.; Rurack, Knut; Sellergren, B. Synthesis, spectroscopic, and analyte-responsive behavior of a polymerizable naphthalimide-based carboxylate probe and molecularly imprinted polymers prepared thereof A naphthalimide-based fluorescent indicator monomer 1 for the integration into chromo- and fluorogenic molecularly imprinted polymers (MIPs) was synthesized and characterized. The monomer was equipped with a urea binding site to respond to carboxylate-containing guests with absorption and fluorescence changes, namely a bathochromic shift in absorption and fluorescence quenching. Detailed spectroscopic analyses of the title compound and various models revealed the signaling mechanism. Titration studies employing benzoate and Z-ʟ-phenylalanine (Z-ʟ-Phe) suggest that indicator monomers such as the title compound undergo a mixture of deprotonation and complex formation in the presence of benzoate but yield hydrogen-bonded complexes, which are desirable for the molecular imprinting process, with weakly basic guests like Z-ʟ-Phe. Compound 1 could be successfully employed in the synthesis of monolithic and thin-film MIPs against Z-ʟ-Phe, Z-L-glutamic acid, and penicillin G. Chromatographic assessment of the selectivity features of the monoliths revealed enantioselective discrimination and clear imprinting effects. Immobilized on glass coverslips, the thin-film MIPs of 1 displayed a clear signaling behavior with a pronounced enantioselective fluorescence quenching dependence and a promising discrimination against cross-analytes. Washington, DC American Chemical Society 2013 The journal of organic chemistry 78 4 1377 1389 10.1021/jo3019522 2016-02-20 OPUS4-27742 Zeitschriftenartikel Ast, S.; Fischer, Tobias; Müller, H.; Mickler, W.; Schwichtenberg, M.; Rurack, Knut; Holdt, H.-J. Integration of the 1,2,3-triazole 'click' motif as a potent signalling element in metal ion responsive fluorescent probes In a systematic approach we synthesized a new series of fluorescent probes incorporating donor-acceptor (D-A) substituted 1,2,3-triazoles as conjugative π-linkers between the alkali metal ion receptor N-phenylaza-[18]crown-6 and different fluorophoric groups with different electron-acceptor properties (4-naphthalimide, meso-phenyl-BODIPY and 9-anthracene) and investigated their performance in organic and aqueous environments (physiological conditions). In the charge-transfer (CT) type probes 1, 2 and 7, the fluorescence is almost completely quenched by intramolecular CT (ICT) processes involving charge-separated states. In the presence of Na+ and K+ ICT is interrupted, which resulted in a lighting-up of the fluorescence in acetonitrile. Among the investigated fluoroionophores, compound 7, which contains a 9-anthracenyl moiety as the electron-accepting fluorophore, is the only probe which retains light-up features in water and works as a highly K+/Na+-selective probe under simulated physiological conditions. Virtually decoupled BODIPY-based 6 and photoinduced electron transfer (PET) type probes 3-5, where the 10-substituted anthracen-9-yl fluorophores are connected to the 1,2,3-triazole through a methylene spacer, show strong ion-induced fluorescence enhancement in acetonitrile, but not under physiological conditions. Electrochemical studies and theoretical calculations were used to assess and support the underlying mechanisms for the new ICT and PET 1,2,3-triazole fluoroionophores. Weinheim Wiley-VCH Verl. 2013 Chemistry - A European journal 19 9 2990 3005 10.1002/chem.201201575 2016-02-20 OPUS4-27783 Zeitschriftenartikel Hecht, Mandy; Fischer, Tobias; Dietrich, Paul; Kraus, Werner; Descalzo López, Ana Belén; Unger, Wolfgang; Rurack, Knut Fluorinated Boron-Dipyrromethene (BODIPY) dyes: bright and versatile probes for surface analysis A family of bright boron-dipyrromethene-type fluorophores with a high number of fluorine atoms (F-BODIPYs) has been developed and characterized by X-ray crystallography and optical spectroscopy. The introduction of 3,5-bis(trifluoromethyl)phenyl and pentafluorophenyl moieties significantly enhances the photostability of such dyes, yielding for instance photostable near-infrared (NIR) fluorophores that show emission maxima>750 nm, when the BODIPY's π system is extended with two (dimethylamino)styryl and (dimethylamino)naphthastyryl moieties, or green-emitting BODIPYs with fluorescence quantum yields of unity. When equipped with a suitable group that selectively reacts for instance with amines, F-BODIPYs can be used as potent dual labels for the quantification of primary amino groups on surfaces by X-ray photoelectron spectroscopy (XPS) and fluorescence, two powerful yet complementary tools for the analysis of organic surface functional groups. The advantage of reactive F-BODIPYs is that they allow a fast and non-destructive mapping of the labelled supports with conventional fluorescence scanners and a subsequent quantification of selected areas of the same sample by the potentially traceable XPS technique. The performance is exemplarily shown here for the assessment of the amino group density on SiO2 supports, one of the most common reactive silica supports, in particular, for standard microarray applications. Weinheim Wiley-VCH-Verl. 2013 ChemistryOpen 2 1 25 38 10.1002/open.201200039 2016-02-20 OPUS4-17511 Zeitschriftenartikel Descalzo López, Ana Belén; Xu, H.-J.; Xue, Z.-L.; Hoffmann, Katrin; Shen, Z.; Weller, Michael G.; You, X.-Z.; Rurack, Knut Phenanthrene-Fused Boron-Dipyrromethenes as Bright Long-Wavelength Fluorophores A new class of boron-dipyrromethene (BDP or BODIPY) dyes was obtained by phenanthrene fusion to the β-pyrrole positions, absorbing in the wavelength range of important laser sources. Despite a 'propeller-like' distorted structure in the crystalline state, the chromophore absorbs (log ε ≥ 5) and fluoresces (Φf ≥ 0.8) strongly and can be easily turned into a fluorescence light-up probe. Incorporation into latex beads produces bright and photostable single-dye and Förster Resonance Energy Transfer (FRET) particles for microscopy applications. Washington, DC American Chemical Society 2008 Organic letters 10 8 1581 1584 10.1021/ol800271e 2016-02-19 OPUS4-17512 Zeitschriftenartikel Martínez, R.; Sancenón, F.; Hoffmann, Katrin; Rurack, Knut; Descalzo López, Ana Belén Materiales híbridos en química analítica El desarrollo de receptores sintéticos complejos basados en conceptos de la química supramolecular no garantiza en ocasiones un reconocimiento molecular selectivo. Una alternativa en ciertos aspectos más simple y prometedora es el empleo de materiales híbridos orgánico-inorgánicos preparados mediante la funcionalización de sólidos inorgánicos porosos con receptores sintéticos adecuados. El anclaje de estos sistemas coordinantes a un soporte sólido da lugar a ciertos efectos sinérgicos que no están presentes ni en el material inicial ni en el receptor por separado y que sugieren que estos nuevos materiales híbridos pueden ser empleados en el desarrollo de nuevos sensores y nuevos protocolos de reconocimiento molecular y/o iónico. The development of synthetic receptors based in supramolecular chemistry concepts will no allow a selective molecular recognition. A more simple, convenient and innovative approach relies on the use of organic-inorganic hybrid materials. These hybrid materials will be prepared by the grafting of certain synthetic receptors onto porous inorganic solids. The grafting of these coordinating systems onto a solid support leads to synergic effects that are hardly achievable with only the synthetic receptors or the solids alone. The presence of these synergic effects suggests that these organic-inorganic hybrid materials will be used for the development of novel sensory systems and novel molecular and/or ionic recognitionprotocols. Springer Real Sociedad Espanola de Química 2007 Anales de la Real Sociedad Espanola de Química 103 4 22 27 2016-02-19 OPUS4-16084 Zeitschriftenartikel García-Acosta, B.; Martínez-Mánez, Ramon; Sancenón, F.; Soto, J.; Rurack, Knut; Spieles, Monika; García-Breijo, E.; Gil, L. Ditopic N-Crowned 4-(p-Aminophenyl)-2,6-diphenylpyridines: Implications of Macrocycle Topology on the Spectroscopic Properties, Cation Complexation, and Differential Anion Responses A family of N-crowned 4-p-(aminophenyl)-2,6-diphenylpyridines DA (1-6) has been synthezised, characterized, and studied as potential hosts for the signaling of cationic and anionic guests. The ditopic probes contain two coordination sites, a monodentate 2,6-diphenylpyridine and an anilino group with macrocycles of different ring size, denticity, and type of secondary heteroatom (O and/or S). X-ray structure analysis of aza-oxa-thia-crowned 5 indicated a largely planar chromophore. Optical spectroscopic and electrochemical studies revealed that the anilino-type donor (D) and the 2,6-diphenylpyridine acceptor (A) are strongly -conjugated, entailing intense intramolecular charge-transfer absorption bands at 340 nm. Binding studies with protons and metal ions (M = Cu2+, Zn2+, Hg2+, Fe3+, Pb2+, Ni2+, Cd2+) showed shifts of the band to the visible (440 nm) when coordination at the pyridine group occurs, strengthening its acceptor character. In contrast, no band in the visible is formed if binding takes place at the anilino group. Three different responses were found for various pairs of DA and M: selective metal coordination to D or A as well as coordination at both sites. A selective response was found for 5 and Hg2+. Because of the multitude of coordination-induced effects, the DA-M ensembles were further employed for differential anion sensing. In this protocol, the addition of an anion X to a certain, weakly coordinated DA-M can (i) lead to the formation of a ternary ion pair complex (DA-M-X), (ii) change the preference for A or D coordination, (iii) induce dissociation of the complex, or (iv) can have no effect. Various patterns of absorption changes were obtained as a result of different responses (i)-(iv) of the DA-M's in the presence of various X's. Data analysis yielded recognition patterns for acetate, F- and CN-, demonstrating the potential of simple chromogenic host-guest pairs for differential anion signaling. Washington, DC American Chemical Society 2007 Inorganic Chemistry 46 8 3123 3135 10.1021/ic062069z 2016-02-19 OPUS4-16085 Zeitschriftenartikel Rurack, Knut; Trieflinger, C.; Kovalchuck, Anton V.; Daub, J. An ionically driven molecular IMPLICATION gate operating in fluorescence Mode An asymmetrically core-extended boron-dipyrromethene (BDP) dye was equipped with two electron-donating macrocyclic binding units with different metal ion preferences to operate as an ionically driven molecular IMPLICATION gate. A Na+-responsive tetraoxa-aza crown ether (R2) was integrated into the extended π system of the BDP chromophore to trigger strong intramolecular charge transfer (ICT2) fluorescence and guarantee cation-induced spectral shifts in absorption. A dithia-oxa-aza crown (R1) that responds to Ag+ was attached to the meso position of BDP in an electronically decoupled fashion to independently control a second ICT1 process of a quenching nature. The bifunctional molecule is designed in such a way that in the absence of both inputs, ICT1 does not compete with ICT2 and a high fluorescence output is obtained (InA=InB=0→Out=1). Accordingly, binding of only Ag+ at R1 (InA=1, InB=0) as well as complexation of both receptors (InA=InB=1) also yields Out=1. Only for the case in which Na+ is bound at R2 and R1 is in its free state does quenching occur, which is the distinguishing characteristic for the InA=0 and InB=1→Out=0 state that is required for a logic IMPLICATION gate and Boolean operations such as IF-THEN or NOT. Weinheim Wiley-VCH Verl. 2007 Chemistry - A European journal 13 32 8998 9003 10.1002/chem.200700858 2016-02-19 OPUS4-16080 Zeitschriftenartikel Descalzo López, Ana Belén; Hoffmann, Katrin; Rurack, Knut; Martínez-Mánez, Ramon; Sancenón, F. Hybridmaterialien in der analytischen Chemie Weinheim Wiley-VCH Verl. Gesellschaft Deutscher Chemiker 2007 Nachrichten aus der Chemie 55 02 124 129 2016-02-19 OPUS4-16081 Zeitschriftenartikel Ros-Lis, J.V.; Martínez-Mánez, Ramon; Sancenón, F.; Soto, J.; Rurack, Knut; Weißhoff, Hardy Signalling Mechanisms in Anion-Responsive Push-Pull Chromophores: The Hydrogen-Bonding, Deprotonation and Anion-Exchange Chemistry of Functionalized Azo Dyes A family of azo dyes containing amide (1), urea (2), thiourea (3), carbamate (4) or amino (5) hydrogen-bond donating groups were synthesized and their response toward anions was studied. Acetonitrile solutions of 1-5 show bright yellow colours, due to charge-transfer bands in the 375-400 nm region, slightly modulated by the electron donor strength of the group attached to the 4 end of the 4-nitroazobenzene scaffold. Anions of different shape and size (i.e., spherical F-,Cl-, Br- and I-, planar and tetrahedral oxoanions such as NO3-, H2PO4- and HSO4-, carboxylates such as acetate and benzoate and the linear anions cyanide and thiocyanate) were employed in the recognition studies. Two different effects were distinguished: (i) bathochromic shifts of <40 nm to pale orange, due to anion coordination, and (ii) strong red shifts of ca. 200 nm with a concomitant colour change to blue, due to deprotonation. This behaviour was explained as a balance between the deprotonation tendency of the binding sites in the different receptors and the proton affinities of the anions. Semiempirical calculations were carried out to evaluate the hydrogen bond-donating abilities of the anions and the dyes and a good correlation with the experimentally found values was observed. Stability constants for the receptor-anion complexes were determined spectrophotometrically and the different responses toward fluoride and acetate were assessed by NMR titration experiments. Finally, as a special case, we also report the use of this family of compounds as colorimetric carbon dioxide sensors through reaction with the unprotonated forms of the azo dyes. Weinheim Wiley-VCH Verl. 2007 European journal of organic chemistry 2007 15 2449 2458 10.1002/ejoc.200601111 2016-02-19 OPUS4-17393 Zeitschriftenartikel Köster, D.; Mayer-Enthart, Elke; Sialelli, J.; Rurack, Knut; Resch-Genger, Ute; Seitz, H. Hula Hoop für DNA - Eine hoch sensitive Detektionsmethode für DNA Microarrays DNA Microarrays, auch als „DNA-Chips“ bekannt, werden verwendet, um das Vorkommen von Genen bzw. Gentranskripten zu analysieren. Sie finden breite Anwendung in der Diagnostik, der Genomanalyse und bei der Erstellung von Genexpressionsprofilen. Vor der Analyse muß auf Grund der oftmals geringen Menge an Probenmaterial eine Vervielfältigung der Probe durchgeführt werden, die jedoch leicht zu Fehlern führt. Im Rahmen dieses Projektes werden zwei experimentelle Ansätze verfolgt, durch die ohne einen Verlust an Sensitivität eine Vervielfältigung der Probe vermieden werden kann, 1) das Etablieren eines RCA-basierten Microarray Assays und 2) die Optimierung des Assays für die Detektion der Fluoreszenzsignale. Berlin DHGP Wissenschaftliches Koordinierungskomitee des Deutschen Humangenomprojektes (DHGP), Wissenschaftliches Koordinierungskomitee des Projektes Genomanalyse im Biologischen System Pflanze (GABI) 2008 GenomXPress: Informationen aus der deutschen Genomforschung 1 23 25 2016-02-19 OPUS4-17632 Zeitschriftenartikel Descalzo López, Ana Belén; Xu, H.-J.; Shen, Z.; Rurack, Knut Red/Near-infrared Boron-Dipyrromethene Dyes as Strongly Emitting Fluorophores New York, NY New York Academy of Sciences 2008 Annals of the New York academy of sciences 1130 164 171 10.1196/annals.1430.016 2016-02-19 OPUS4-18443 Zeitschriftenartikel Ros-Lis, J.V.; Casasús, R.; Comes, M.; Coll, C.; Marcos, M. Dolores; Martínez-Mánez, Ramon; Sancenón, F.; Soto, J.; Amorós, P.; El Haskouri, J.; Garró, N.; Rurack, Knut A mesoporous 3D hybrid material with dual functionality for Hg2+ detection and adsorption Weinheim Wiley-VCH Verl. 2008 Chemistry - A European journal 14 8267 8278 10.1002/chem.200800632 2016-02-19 OPUS4-18444 Zeitschriftenartikel Ros-Lis, J.V.; Martínez-Mánez, Ramon; Sancenón, F.; Soto, J.; Spieles, Monika; Rurack, Knut Aquaraines as reporter units: insights into their photophysics, protonation, and metal-ion coordination behaviour Weinheim Wiley-VCH Verl. 2008 Chemistry - A European journal 14 10101 10114 10.1002/chem.200800300 2016-02-19 OPUS4-18445 Beitrag zu einem Sammelband Rurack, Knut Resch-Genger, Ute; O.S. Wolfbeis, Fluorescence Quantum Yields:Methods of Determination and Standards The fluorescence quantum yield Φ f is a key property that characterizes the ability of a fluorophore to convert absorbed photons into emitted photons under various environmental conditions. Knowledge of it is important for the successful development of fluorometric indication and visualization methods and for the understanding of light-driven processes in the natural sciences. Φ f is a molecule- or material-related parameter and can thus significantly differ from the fraction of absorbed photons that are actually measured as the fluorescence signal of a certain sample, e.g., when the signal is modulated by reabsorption, self-quenching or polarization effects. The determination of Φ f can be performed in absolute measurements or relative to a fluorescent standard material with a known Φ f by optical or calorimetric methods. Here the different procedures and techniques are described and compared, and the suitability of a representative number of dyes that have been proposed as fluorescence reference materials in the past 25 years is discussed. Besides addressing specific issues such as low-temperature measurements and the appropriate choice of standards and measurement conditions, we conclude with recommendations for better standardization and quality management in this area. Springer 2008 Standardization and Quality Assurance in Fluorescence Measurements I - Techniques 5 978-3-540-75206-6 Part B 101 145 10.1007/4243_2008_019 2016-02-19 OPUS4-16139 Zeitschriftenartikel Descalzo López, Ana Belén; Marcos, M. Dolores; Monte, Christian; Martínez-Mánez, Ramon; Rurack, Knut Mesoporous silica materials with covalently anchored phenoxazinone dyes as fluorescent hybrid materials for vapour sensing Cambridge Royal Society of Chemistry 2007 Journal of materials chemistry 17 4716 4723 10.1039/b707473e 2016-02-19 OPUS4-16447 Zeitschriftenartikel Wu, D.; Descalzo López, Ana Belén; Weik, F.; Emmerling, Franziska; Shen, Z.; You, X.-Z.; Rurack, Knut Ein kernmodifiziertes Rubyrin mit meso-Aryl-Subsituenten und Phenanthren-anellierten Pyrrolringen als hoch konjugierter NIR-Farbstoff und Hg2+-Sonde Weinheim Wiley-VCH Gesellschaft Deutscher Chemiker 2008 Angewandte Chemie 120 1 199 203 10.1002/ange.200702854 2016-02-19 OPUS4-16448 Zeitschriftenartikel Wu, D.; Descalzo López, Ana Belén; Weik, F.; Emmerling, Franziska; Shen, Z.; You, X.-Z.; Rurack, Knut A core-modified Rubyrin with meso-aryl substituents and phenanthrene-fused pyrrole rings: a highly conjugated near-infrared dye and Hg2+ probe Weinheim Wiley-VCH Gesellschaft Deutscher Chemiker 2008 Angewandte Chemie / International Edition 47 1 193 197 10.1002/Anie.200702854 2016-02-19 OPUS4-17658 Zeitschriftenartikel Leiterer, Jork; Grabolle, Markus; Rurack, Knut; Resch-Genger, Ute; Ziegler, J.; Nann, T.; Panne, Ulrich Acoustically Levitated Droplets - A Contactless Sampling Method for Fluorescence Studies Acoustic levitation is used as a newtool to study concentration-dependent processes influorescence spectroscopy. With this technique, small amounts of liquid and solid samples can be measured without the need for sample supports or containers, which often limits signal acquisition and can even alter sample properties due to interactions with the support material. We demonstrate that, because of the small sample volume, fluorescence measurements at high concentrations of an organic dye are possible without the limitation of inner-filter effects, which hamper such experiments in conventional, cuvette-based measurements. Furthermore, we show that acoustic levitation of liquid samples provides an experimentally simple way to study distance-dependent fluorescence modulations in semiconductor nanocrystals. The evaporation of the solvent during levitation leads to a continuous increase of solute concentration and can easily be monitored by laser-induced fluorescence. New York, NY New York Academy of Sciences 2008 Annals of the New York academy of sciences 1130 78 84 10.1196/annals.1430.039 2016-02-19 OPUS4-17633 Zeitschriftenartikel Mayer-Enthart, Elke; Sialelli, Julien; Rurack, Knut; Resch-Genger, Ute; Köster, D.; Seitz, H. Toward Improved Biochips Based on Rolling Circle Amplification - Influences of the Microenvironment on the Fluorescence Properties of Labeled DNA Oligonucleotides New York, NY New York Academy of Sciences 2008 Annals of the New York academy of sciences 1130 287 292 10.1196/annals.1430.022 2016-02-19 OPUS4-4889 Posterpräsentation Rurack, Knut Macrocycles in a Different Light: The Influence of the Nature and Substitution Pattern of Heteroatoms on the Photophysics of Chromophore-Appended Crown Ethers 2003 28th International Symposium on Macrocyclic Chemistry 28th International Symposium on Macrocyclic Chemistry Gdansk, Poland 2003-07-13 2003-07-18 2016-02-19 OPUS4-4894 Posterpräsentation Rurack, Knut Intramolecular Charge-Transfer Characteristics of Fluorescent Donor-[Ethynyl-Donor]n (n=1,2) Dyads and Triads 2003 8th Conference on Methods and Applications of Fluorescence: Spectroscopy, Imaging and Probes 8th Conference on Methods and Applications of Fluorescence: Spectroscopy, Imaging and Probes Prague, Czech Republic 2003-08-24 2003-08-27 2016-02-19 OPUS4-12171 Zeitschriftenartikel Hennrich, G.; Rurack, Knut; Spieles, Monika Reconfiguration of the Symmetry and Charge-Transfer Characteristics of a Triply Crowned 1,3,5-Tris(arylalkynyl)mesitylene by Successive Metal Ion Complexation A triply benzocrown-ether-functionalized trialkynylmesitylene derivative with C3 symmetry as well as its linear analogue have been synthesized and their optical properties have been studied by UV/Vis absorption, steady-state and time-resolved fluorescencece spectroscopy. The spectroscopic investigation of the uncomplexed compounds revealed the nature of the electronic and excitonic communication pathway in the ground and excited states of the all-meta-substituted chromophore system. Upon cation complexation, the octopolar character of the free trialkynyl compound becomes dipolar and finally returns to octopolar in the fully complexed species. Weinheim Wiley-VCH Verl. 2006 European journal of organic chemistry 2006 2 516 521 10.1002/ejoc.200500595 2016-02-19 OPUS4-12172 Zeitschriftenartikel Trieflinger, C.; Röhr, Holger; Rurack, Knut; Daub, J. Multiples Schalten und photogesteuerte Elektrochemilumineszenz einer Dihydroazulen-Bordipyrromethen-Dyade Weinheim Wiley-VCH Gesellschaft Deutscher Chemiker 2005 Angewandte Chemie 117 42 7104 7107 10.1002/ange.200501573 2016-02-19 OPUS4-12175 Zeitschriftenartikel Röhr, Holger; Trieflinger, C.; Rurack, Knut; Daub, J. Proton- and Redox-Controlled Switching of Photo- and Electrochemiluminescence in Thiophenyl-Substituted Boron-Dipyrromethene Dyes A luminescent molecular switch in which the active thiol/disulfide switching element is attached to a meso-phenyl-substituted boron-dipyrromethene (BDP) chromophore as the signalling unit is presented. The combination of these two functional units offers great versatility for multimodal switching of luminescence: 1) deprotonation/protonation of the thiol/thiolate moiety allows the highly fluorescent meso-p-thiophenol-BDP and its nonfluorescent thiolate analogue to be chemically and reversibly interconverted, 2) electrochemical oxidation of the monomeric dyes yields the fluorescent disulfide-bridged bichromophoric dimer, also in a fully reversible process, and 3) besides conventional photoexcitation, the well separated redox potentials of the BDP also allow the excited BDP state to be generated electrochemically (i.e., processes 1) and 2) can be employed to control both photo- and electrochemiluminescence (ECL) of the BDP). The paper introduces and characterizes the various states of the switch and discusses the underlying mechanisms. Investigation of the ortho analogue of the dimer provided insight into potential chromophore-chromophore interactions in such bichromophoric architectures in both the ground and the excited state. Comparison of the optical and redox properties of the two disulfide dimers further revealed structural requirements both for redox switches and for ECL-active molecular ensembles. By employing thiol/disulfide switching chemistry and BDP luminescence features, it was possible to create a prototype molecular ensemble that shows both fully reversible proton- and redox-gated electrochemiluminescence. Weinheim Wiley-VCH Verl. 2006 Chemistry - A European journal 12 3 689 700 10.1002/chem.200500729 2016-02-19 OPUS4-12179 Zeitschriftenartikel Rurack, Knut; Monte, Christian Metallionen auf der Spur Würzburg Vogel 2006 Labor-Praxis 1/2 20 22 2016-02-19 OPUS4-12180 Zeitschriftenartikel Bricks, J.L.; Kovalchuck, Anton V.; Trieflinger, C.; Nofz, Marianne; Büschel, M.; Tolmachev, A.I.; Daub, J.; Rurack, Knut On the Development of Sensor Molecules that Display FeIII-amplified Fluorescence Incorporation of a tailor-made size-restricted dithia-aza-oxa macrocycle, 1-oxa-4,10-dithia-7-aza-cyclododecane, via a phenyl linker into two fluorescent sensor molecules with electronically decoupled, rigidly fixed, and sterically preoriented architectures, a 1,3,5-triaryl-2-pyrazoline and a meso-substituted boron-dipyrromethene (BDP), yields amplified fluorescence in the red-visible spectral range upon binding of FeIII ions. The response to FeIII and potentially interfering metal ions is studied in highly polar aprotic and protic solvents for both probes as well as in neat and buffered aqueous solution for one of the sensor molecules, the BDP derivative. In organic solvents, the fluorescence of both indicators is quenched by an intramolecular charge or electron transfer in the excited state and coordination of FeIII leads to a revival of their fluorescence without pronounced spectral shifts. Most remarkably, the unbound BDP derivative shows dual emission in water and can be employed for the selective ratiometric signaling of FeIII in buffered aqueous solutions. Washington, DC American Chemical Society 2005 Journal of the American chemical society 127 13522 13529 10.1021/ja050652t 2016-02-19 OPUS4-12821 Zeitschriftenartikel Descalzo López, Ana Belén; Martínez-Mánez, Ramon; Sancenón, F.; Hoffmann, Katrin; Rurack, Knut Die supramolekulare Chemie organisch-anorganischer Hybrid-Nanomaterialien Die Entwicklung von Hybridmaterialien mit stark verbesserten Funktionen gelingt durch die Kombination geeigneter Nanomaterialien als Träger mit Motiven aus der supramolekularen Chemie. Diese hetero-supramolekularen Konzepte bieten vielfältige Möglichkeiten, die Lücken zwischen der Molekülchemie, Materialwissenschaften und Nanotechnologie zu schließen. Im Hinblick auf funktionelle Aspekte wurden in jüngster Zeit wichtige Fortschritte erzielt, z. B. verbesserte Erkennungs- und Sensoreigenschaften durch die Anordnung von Molekülen auf vororganisierten Oberflächen, der reversible Aufbau von nanometergroßen Netzwerken und dreidimensionalen Strukturen oder biomimetische und gesteuerte chemische Prozesse in Hybrid-Nanomaterialien, die als Grundlage für hoch spezialisierte Protokolle in dreidimensionalen Gerüststrukturen dienen können. Diese Ansätze ermöglichen eine Feinabstimmung der Eigenschaften von Nanomaterialien und eröffnen neue Perspektiven für die Anwendung supramolekularer Konzepte. Weinheim Wiley-VCH Gesellschaft Deutscher Chemiker 2006 Angewandte Chemie 118 36 6068 6093 10.1002/ange.200600734 2016-02-19 OPUS4-12824 Zeitschriftenartikel Descalzo López, Ana Belén; Martínez-Mánez, Ramon; Sancenón, F.; Hoffmann, Katrin; Rurack, Knut The Supramolecular Chemistry of Organic-Inorganic Hybrid Materials The combination of nanomaterials as solid supports and supramolecular concepts has led to the development of hybrid materials with improved functionalities. These hetero-supramolecular ideas provide a means of bridging the gap between molecular chemistry, materials sciences, and nanotechnology. In recent years, relevant examples have been reported on functional aspects, such as enhanced recognition and sensing by using molecules on preorganized surfaces, the reversible building of nanometer-sized networks and 3D architectures, as well as biomimetic and gated chemistry in hybrid nanomaterials for the development of advanced functional protocols in three-dimensional frameworks. This approach allows the fine-tuning of the properties of nanomaterials and offers new perspectives for the application of supramolecular concepts. Weinheim Wiley-VCH Gesellschaft Deutscher Chemiker 2006 Angewandte Chemie / International Edition 45 36 5924 5948 10.1002/anie.200600734 2016-02-19 OPUS4-4123 Zeitschriftenartikel Kovalchuck, Anton V.; Bricks, Julia; Reck, Günter; Rurack, Knut; Schulz, Burkhard; Szumna, A.; Weißhoff, Hardy A charge transfer-type fluorescent molecular sensor that "lights up" in the visible upon hydrogen bond-assisted complexation of anions Cambridge Royal Society of Chemistry Chemical Society 2004 Chemical communications 1946 1947 10.1039/b405207b 2016-02-19 OPUS4-4124 Zeitschriftenartikel Ros-Lis, J.V.; Martínez-Mánez, Ramon; Rurack, Knut; Sancenón, F.; Soto, J.; Spieles, Monika Highly Selective Chromogenic Signaling of Hg2+ in Aqueous Media at Nanomolar Levels Employing a Squaraine-Based Reporter A chromogenic chemosensor for Hg2+ detection in aqueous media at the nanomolar level has been developed from squaraine scaffoldings. Washington, DC American Chemical Society 2004 Inorganic Chemistry 43 17 5183 5185 10.1021/ic049422q 2016-02-19 OPUS4-4125 Zeitschriftenartikel Shen, Z.; Röhr, Holger; Rurack, Knut; Uno, H.; Spieles, Monika; Schulz, Burkhard; Reck, Günter; Ono, N. Boron-Diindomethene (BDI) Dyes and Their Tetrahydrobicyclo Precursors - en Route to a New Class of Highly Emissive Fluorophores for the Red Spectral Range The X-ray crystallographic, optical spectroscopic, and electrochemical properties of a newly synthesized class of boron-diindomethene (BDI) dyes and their tetrahydrobicyclo precursors (bc-BDP) are presented. The BDI chromophore was designed to show intensive absorption and strong fluorescence in an applicationary advantageous spectral range. Its modular architecture permits fusion of a second subunit, for example, a receptor moiety to the dye's core to yield directly linked yet perpendicularly prearranged composite systems. The synthesis was developed to allow facile tuning of the chromophore platform and to thus adjust its redox properties. X-ray analysis revealed a pronounced planarity of the chromophore in the case of the BDIs, which led to a remarkable close packing in the crystal of the simplest derivative. On the other hand, deviation from planarity was found for the diester-substituted bc-BDP benzocrown that exhibits a butterfly-like conformation in the crystal. Both families of dyes show charge- or electron-transfer-type fluorescence-quenching characteristics in polar solvents when equipped with a strong donor in the meso-position of the core. These processes can be utilized for signaling purposes if an appropriate receptor is introduced. Further modification of the chromophore can invoke such a guest-responsive intramolecular quenching process, also for receptor groups of low electron density, for example, benzocrowns. In addition to the design of various prototype molecules, a promising fluoroionophore for Na+ was obtained that absorbs and emits in the 650 nm region and shows a strong fluorescence enhancement upon analyte binding. Furthermore, investigation of the remarkable solvatokinetic fluorescence properties of the butterfly-like bc-BDP derivatives suggested that a second intrinsic nonradiative deactivation channel can play a role in the photophysics of boron-dipyrromethene dyes. Weinheim Wiley-VCH Verl. 2004 Chemistry - A European journal 10 4853 4871 10.1002/chem.200400173 2016-02-19 OPUS4-7305 Zeitschriftenartikel Trieflinger, C.; Rurack, Knut; Daub, J. "Turn ON/OFF your LOV light": Bordipyrromethen-Flavin-Dyaden als biomimetische, von der LOV-Domäne abgeleitete Schalter Weinheim Wiley-VCH Gesellschaft Deutscher Chemiker 2005 Angewandte Chemie 117 15 2328 2331 2016-02-19 OPUS4-28970 Zeitschriftenartikel Climent Terol, Estela; Mondragón, L.; Martínez-Mánez, Ramon; Sancenón, F.; Marcos, M. Dolores; Murguía, J.R.; Amorós, P.; Rurack, Knut; Pérez-Payá, E. Selektiver, hoch empfindlicher und schneller Nachweis genomischer DNA mit gesteuerten Materialien am Beispiel von Mycoplasma Mit DNA verschlossene und mit Farbstoff beladene mesoporöse Siliciumdioxid-Nanopartikel wurden zum Nachweis von Mycoplasma bis zu einer Nachweisgrenze von ca. 70 genomischen DNA-Kopien pro µL in real kontaminierten Zellkulturmedien ohne die Hilfe von PCR-Techniken eingesetzt. Weinheim Wiley-VCH Gesellschaft Deutscher Chemiker 2013 Angewandte Chemie 125 34 9106 9110 10.1002/ange.201302954 2016-02-20 OPUS4-28976 Zeitschriftenartikel Climent Terol, Estela; Mondragón, L.; Martínez-Mánez, Ramon; Sancenón, F.; Marcos, M. Dolores; Murguía, J.R.; Amorós, P.; Rurack, Knut; Pérez-Payá, E. Selective, highly sensitive, and rapid detection of genomic DNA by using gated materials: Mycoplasma detection Come and gate it: DNA-capped mesoporous silica nanoparticles loaded with a dye are used to detect the common contaminate Mycoplasma in real contaminated cell-culture media without needing polymerase chain reaction (PCR) techniques, at a detection limit in the range of 70 DNA genome copies µL-1. Weinheim Wiley-VCH Gesellschaft Deutscher Chemiker 2013 Angewandte Chemie / International Edition 52 34 8938 8942 10.1002/anie.201302954 2016-02-20 OPUS4-28940 Zeitschriftenartikel Hecht, Mandy; Climent Terol, Estela; Biyikal, Mustafa; Sancenón, F.; Martínez-Mánez, Ramon; Rurack, Knut Gated hybrid delivery systems: En route to sensory materials with inherent signal amplification Hybrid nanoparticles with a large specific surface area are a particularly exciting vehicle for delivery applications. Such highly porous or container-like structures, usually prepared from silica and frequently from gold, can incorporate a large number of chemical substances such as drug and/or indicator molecules. When equipped with a chemically or physically addressable gating function at the openings of the voids, the release of the cargo can be controlled at will. Because many more molecules can be stored as cargo in the pores of the support than there are functional groups as anchoring sites for the gating entities attached to the outer surface (for efficient pore capping), the systems possess inherent features of (signal) amplification. The present article will introduce various design strategies for different types of physical (light, temperature, magnetism) and chemical (pH, metal ions, anion, small organic molecules, enzymes) stimuli in connection with drug and indicator release. We will highlight exciting aspects of combining both features in theranostic applications and will stress which requirements still have to be met by many of the systems to be readily applicable in a sensory context. Amsterdam Elsevier 2013 Coordination chemistry reviews 257 17-18 2589 2606 10.1016/j.ccr.2013.03.020 2016-02-20 OPUS4-28947 Posterpräsentation Rurack, Knut Test strip-based fluorescence detection of fluoride in aqueous media with a BODIPY-linked hydrogen bonding receptor 2013 International Conference on Photochemistry (ICP 2013) International Conference on Photochemistry (ICP 2013) Leuven, Belgium 2013-07-21 2013-07-26 2016-02-20 OPUS4-28948 Posterpräsentation Rurack, Knut Preparation of hybrid particle architectures for single microparticle-based detection in suspension arrays using FRET 2013 Tag der Chemie 2013 Tag der Chemie 2013 Potsdam, Germany 2013-06-27 2016-02-20 OPUS4-28949 Vortrag Rurack, Knut Gated Hybrid Sensor Materials for Amplified Fluorescence Sensing 2013 E-MRS 2013 Spring Meeting E-MRS 2013 Spring Meeting Strasbourg, France 2013-05-27 2013-05-31 2016-02-20 OPUS4-29323 Zeitschriftenartikel Resch-Genger, Ute; Rurack, Knut Determination of the photoluminescence quantum yield of dilute dye solutions (IUPAC technical report) Procedures for the determination of photoluminescence quantum yields with optical methods are addressed, and challenges associated with these measurements are discussed. Special emphasis is dedicated to relative measurements of fluorescent (i.e., short excited-state lifetime), transparent, dilute dye solutions in conventional cuvettes in a 0°/90° measurement geometry. Recommendations on the selection of suitable quantum yield standards are presented, and requirements for the documentation of photoluminescence quantum yields are derived. Research Triangle Park, NC Union International Union of Pure and Applied Chemistry (IUPAC) 2013 Pure and applied chemistry 85 10 2005 2026 10.1351/PAC-REP-12-03-03 2016-02-20 OPUS4-29507 Zeitschriftenartikel Gotor, Raúl; Costero, A. M.; Gil, S.; Parra, M.; Gavina, P.; Rurack, Knut Boolean operations mediated by an ion-pair receptor of a multi-readout molecular logic gate A heteroditopic BODIPY dye that performs all basic Boolean operations with a cation (K+) and an anion (F-) as inputs and absorption, transmission and fluorescence as outputs is described. The molecular logic gate can also act as a digital comparator between the inputs. Cambridge Royal Society of Chemistry Chemical Society 2013 Chemical communications 49 94 11056 11058 10.1039/c3cc45377d 2016-02-20 OPUS4-29508 Zeitschriftenartikel Climent Terol, Estela; Gröninger, Delia; Hecht, Mandy; Walter, Astrid; Martínez-Mánez, Ramon; Weller, Michael G.; Sancenón, F.; Amorós, P.; Rurack, Knut Selective, sensitive, and rapid analysis with lateral-flow assays based on antibody-gated dye-delivery systems: The example of triacetone triperoxide Set them free: Brightly fluorescent indicators that are loaded into mesoporous silica nanoparticle carriers, capped with bulky antibodies, are released into the lateral flow of a test strip upon analyte arrival. Integration of the system into a rapid, simple flow test with fluorescence readout is applied for the selective and sensitive determination of the presence of triacetone triperoxide (TATP) as a prototype small-molecule analyte (see figure). Weinheim Wiley-VCH Verl. 2013 Chemistry - A European journal 19 13 4117 4122 10.1002/chem.201300031 2016-02-20 OPUS4-29563 Vortrag Rurack, Knut Long-wavelength Polymethine Dyes and Probes - Prospects, Pitfalls and Color Rules 2013 Control of Electronic Properties of Aggregated pi-Conjugated Molecules Control of Electronic Properties of Aggregated pi-Conjugated Molecules Würzburg, Germany 2013-07-11 2013-07-11 2016-02-20 OPUS4-29564 Vortrag Rurack, Knut Implementing Signal Generation Features in Organic Dyes 2013 Control of Electronic Properties of Aggregated pi-Conjugated Molecules Control of Electronic Properties of Aggregated pi-Conjugated Molecules Würzburg, Germany 2013-07-10 2013-07-10 2016-02-20 OPUS4-29565 Vortrag Rurack, Knut Test strip-based fluorescence detection of fluoride in aqueous media with a BODIPY-linked hydrogen bonding receptor 2013 26th International Conference on Photochemistry (ICP 2013) 26th International Conference on Photochemistry (ICP 2013) Leuven, Belgium 2013-07-21 2013-07-26 2016-02-20 OPUS4-19212 Beitrag zu einem Sammelband Rurack, Knut; Martínez-Mánez, Ramon Charles M. Lukehart, ; Robert A. Scott, Functional Supramolecular Hybrid Materials The combination of suitable nanoscopic inorganic supports with supramolecular concepts and bioconjugation strategies opens up exciting perspectives for the development of bioinorganic and organic–inorganic hybrid materials with improved functionalities. Many of the examples from the period 2004 to mid-2007 reviewed here bridge the gap between molecules, materials sciences, biochemistry, and nanotechnology. The synergistic use of these approaches has led to the advancement of various functions such as enhanced recognition, amplified signaling, the controlled assembly and disassembly of aggregates and 3-D architectures. Many of the implemented active functions can be carried out in a reversible and directed fashion on purpose by triggering with an external stimulus. These ideas bring tunability to properties of inorganic solids and new perspectives of application to biochemical and supramolecular concepts. Classic inorganic chemistries such as metal or semiconductor nanoparticles, silica or carbon materials, and coordination chemistry are thus elevated to another level of sophistication and contribute significantly to frontier research areas in directed transport and delivery, nanoelectronics and mechanics, chip technology, smart materials, memory devices, and bioanalytics. Chichester Wiley 2008 Nanomaterials: Inorganic and Bioinorganic Perspectives 978-0470-51644-7 789 812 2016-02-19 OPUS4-19213 Beitrag zu einem Sammelband Rurack, Knut; Martínez-Mánez, Ramon Charles M. Lukehart, ; Robert A. Scott, Biomimetic chemistry of hybrid materials The article discusses representative examples published in the field of functional biomimetic chemistry of hybrid materials between 2004 and mid-2007. First, we focus on the modification of morphological aspects of (bio)organic–inorganic hybrid materials to create sophisticated gating and switching mechanisms. The architecture of the systems is presented and the elements of control by external stimuli that have been established in recent years, such as optical, electrochemical, chemical, thermal, or magnetic means, are described. Various functions ranging from (site-specific) delivery to indication at the nanometric level are reported. Next we develop the idea of utilizing hybrid frameworks for biomimetic signaling inspired by the way nature has created binding pockets and the concept of induced-fit. Such a merging of inorganic scaffolds with supramolecular concepts results in enhanced molecular recognition and signaling. Finally selected recent advances in the field of hybrid biomimetic motors both of linear and rotary types are presented. The contribution shows how novel biomimetic functions can arise from synergisms between specifically designed hybrid materials and the implementation of supramolecular and/or bioorganic concepts. Chichester Wiley 2008 Nanomaterials: Inorganic and Bioinorganic Perspectives 978-0470-51644-7 31 50 2016-02-19 OPUS4-20430 Vortrag Rurack, Knut Development and Application of Particle-based Analytical Platforms for Photo- and Fluorometric Detection 2009 FUTURSEN 2009-Symposium, Universidad Complutense Madrid FUTURSEN 2009-Symposium, Universidad Complutense Madrid Madrid, Spain 2009-09-18 2009-09-18 2016-02-19 OPUS4-20432 Vortrag Rurack, Knut Red and NIR Polymethinic Dyes and Probes - Prospects, Pitfalls and Latest Developments in Color Rules 2009 Department of Chemistry Department of Chemistry Valencia, Spain 2009-11-26 2009-11-26 2016-02-19 OPUS4-20644 Posterpräsentation Rurack, Knut Biomimetically Inspired Sensing of Ionic and Neutral Species with Organically Modified Mesoporous Silica Materials 2009 First International Conference on Multifunctional, Hybrid and Nanomaterials First International Conference on Multifunctional, Hybrid and Nanomaterials Tours, France 2009-03-15 2009-03-19 2016-02-19 OPUS4-20957 Zeitschriftenartikel Wang, Y.-W.; Descalzo López, Ana Belén; Shen, Z.; You, X.-Z.; Rurack, Knut Dihydronaphthalene-fused Boron-dipyrromethene (BODIPY) dyes: insight into the electronic and conformational tuning modes of BODIPY fluorophores A new series of boron-dipyrromethene (BDP, BODIPY) dyes with dihydronaphthalene units fused to the β-pyrrole positions (1 a-d, 2) has been synthesised and spectroscopically investigated. All the dyes, except pH-responsive 1 d in polar solvents, display intense emission between 550-700 nm. Compounds 1 a and 1 b with a hydrogen atom and a methyl group in the meso position of the BODIPY core show spectroscopic properties that are similar to those of rhodamine 101, thus rendering them potent alternatives to the positively charged rhodamine dyes as stains and labels for less polar environments or for the dyeing of latex beads. Compound 1 d, which carries an electron-donating 4-(dimethylamino)phenyl group in the meso position, shows dual fluorescence in solvents more polar than dibutyl ether and can act as a pH-responsive "light-up" probe for acidic pH. Correlation of the pKa data of 1 d and several other meso-(4-dimethylanilino)-substituted BODIPY derivatives allowed us to draw conclusions on the influence of steric crowding at the meso position on the acidity of the aniline nitrogen atom. Preparation and investigation of 2, which carries a nitrogen instead of a carbon as the meso-bridgehead atom, suggests that the rules of colour tuning of BODIPYs as established so far have to be reassessed; for all the reported couples of meso-C- and meso-N-substituted BODIPYs, the exchange leads to pronounced redshifts of the spectra and reduced fluorescence quantum yields. For 2, when compared with 1 a, the opposite is found: negligible spectral shifts and enhanced fluorescence. Additional X-ray crystallographic analysis of 1 a and quantum chemical modelling of the title and related compounds employing density functional theory granted further insight into the features of such sterically crowded chromophores. Weinheim Wiley-VCH Verl. 2010 Chemistry - A European journal 16 9 2887 2903 10.1002/chem.200902527 2016-02-19 OPUS4-26849 Vortrag Rurack, Knut Gated Fluorogenic Hybrid Sensor Materials with Inherent Signal Amplification 2012 40 International Conference on Coordination Chemistry (ICCC40) 40 International Conference on Coordination Chemistry (ICCC40) Valencia, Spain 2012-09-09 2012-09-13 2016-02-19 OPUS4-26873 Zeitschriftenartikel Rurack, Knut Nanoparticle-based sensors: Striped cation-trappers Toxic metal cations in environmental samples can be detected with ultrahigh sensitivity through measurements of the tunnelling current across crosslinked films of nanoparticles decorated with striped monolayers of organic ligands. Basingstoke Nature Publishing Group 2012 Nature materials 11 11 913 914 10.1038/nmat3469 2016-02-19 OPUS4-27113 Zeitschriftenartikel Wang, Y.-W.; Descalzo López, Ana Belén; Shen, Z.; You, X.-Z.; Rurack, Knut Dihydronaphthalene-fused Boron-dipyrromethene (BODIPY) dyes: insight into the electronic and conformational tuning modes of BODIPY fluorophones Weinheim Wiley-VCH Verl. 2012 Chemistry - A European journal 18 23 7306 7309 10.1002/chem.201201081 2016-02-19 OPUS4-27302 Posterpräsentation Rurack, Knut Development and Characterization of a Photostable Boron-dipyrromethene Dye as a Versatile Probe of the Analysis of Surface Functional Groups 2012 Smart Surfaces 2012 Smart Surfaces 2012 Dublin, Ireland 2012-03-06 2012-03-09 2016-02-20 OPUS4-26118 Beitrag zu einem Sammelband Biyikal, Mustafa; Hecht, Mandy; Martínez-Mánez, Ramon; Rurack, Knut; Sancenón, F. Gale, P.A.; Steed, J.W. Supramolecular hybrid nanomaterials as prospective sensing platforms Supramolecular interactions are vital processes in many chemical sensors, biochemical assays, and other analytical detection schemes. On the background of the current, rapidly developing, and constantly changing requirements for (bio)analytical techniques, the classical molecular host is increasingly overburdened to accomplish a specific analytical task with the desired selectivity and sensitivity. Instead, other signaling strategies have to be conceived that overcome the limits in signal output, dynamic range, or compound targeting, which are imminent to various traditional methods. A very promising approach is the combination of concepts of supramolecular chemistry with nanostructured or nanoscopic inorganic materials, that is, the development of hybrid sensor materials. Such hybrids often lead to improved functionality and enhanced performance, and the present chapter discusses the contributory features in relation to the major aspects, which are related to the enhanced coordination by the preorganization of binding sites, signal amplification by the preorganization on surfaces, aggregation-mediated signaling, surface-modification-based signaling, the tuning of selectivity through polarity and size, and gated signaling. John Wiley & Sons 2012 Supramolecular chemistry: From molecules to nanomaterials 978-0-470-74640-0 3669 3698 10.1002/9780470661345.smc199 2016-02-19 OPUS4-29631 Vortrag Rurack, Knut Responsive Dyes and Sensing Matrices: From Moleculary Imprinted Polymers to Nitrocellulose Membranes for Simple Fluorescence Assays 2013 Promotionsverteidigung Promotionsverteidigung Santiago de Compostela, Spain 2013-11-26 2013-11-26 2016-02-20 OPUS4-29818 Beitrag zu einem Tagungsband Wan, Wei; Biyikal, Mustafa; Wagner, R.; Sellergren, B.; Rurack, Knut Enantioselective fluorescence response of molecularly imprinted polymers (MIPs) toward carbobenzyloxy- (Cbz) protected amino acids Integration of a polymerisable fluorescent urea-nitrobenzoxadiazole monomer 1 into a few-nanometre thin molecularly imprinted polymer (MIP) shell coated onto a 300 nm silica core with the tetrabutylammonium salt of N-carbobenzyloxy-L-phenylalanine (Cbz- or Z-ʟ-Phe) as the imprinted template yields core/shell MIP nanoparticles that respond to the designated analyte with a strong fluorescence increase in the visible spectral range. The system shows promising imprinting and enantioselectivity factors of 3.6 and 1.9 when benzylmethylacrylate (BMA) is used as co-monomer and ethylene glycol dimethacrylate (EDMA) as cross-linker. A second, naphthalimide-based fluorescent urea 2 is employed in the preparation of MIP thin-films and monolithic polymers for separation techniques. Spectroscopic and chromatographic studies of the MIPs with the analytes Z-ʟ-Phe, Z-ʟ-glutamic acid (Z-ʟ-Glu) and penicilin G (PenG) revealed the (enantio)selective discrimination behaviour of these materials. Wunstorf AMA Service GmbH 2013 11. Dresdner Sensor Symposium 2013 (Proceedings) 978-3-9813484-5-3 11. Dresdner Sensor Symposium 2013 Dresden, Germany 09.12.2013 11.12.2013 53 58 10.5162/11dss2013/3.2 2016-02-20 OPUS4-55225 Zeitschriftenartikel Sternbaek, L.; Kimani, Martha Wamaitha; Gawlitza, Kornelia; Rurack, Knut; Janicke, B.; Alm, K.; Gjörloff-Wingren, A.; Eriksson, H. Molecularly Imprinted Polymers Exhibit Low Cytotoxic and Inflammatory Properties in Macrophages In Vitro Molecularly imprinted polymers (MIPs) against sialic acid (SA) have been developed as a detection tool to target cancer cells. Before proceeding to in vivo studies, a better knowledge of the overall effects of MIPs on the innate immune system is needed. The aim of this study thus was to exemplarily assess whether SA-MIPs lead to inflammatory and/or cytotoxic responses when administered to phagocytosing cells in the innate immune system. The response of monocytic/macrophage cell lines to two different reference particles, Alhydrogel and PLGA, was compared to their response to SA-MIPs. In vitro culture showed a cellular association of SA-MIPs and Alhydrogel, as analyzed by flow cytometry. The reference particle Alhydrogel induced secretion of IL-1b from the monocytic cell line THP-1, whereas almost no secretion was provoked for SA-MIPs. A reduced number of both THP-1 and RAW 264.7 cells were observed after incubation with SA-MIPs and this was not caused by cytotoxicity. Digital holographic cytometry showed that SA-MIP treatment affected cell division, with much fewer cells dividing. Thus, the reduced number of cells after SA-MIP treatment was not linked to SA-MIPs cytotoxicity. In conclusion, SA-MIPs have a low degree of inflammatory properties, are not cytotoxic, and can be applicable for future in vivo studies. Basel MDPI 2022 Applied Sciences 12 12 1 16 urn:nbn:de:kobv:b43-552250 10.3390/app12126091 https://creativecommons.org/licenses/by/4.0/deed.de 2022-07-11 OPUS4-56463 Zeitschriftenartikel Garrido, E.; Hernández-Sigüenza, G.; Climent, Estela; Marcos, M. D.; Rurack, Knut; Gaviña, P.; Parra, M.; Sancenón, F.; Martí-Centelles, V.; Martínez-Máñez, R. Strip-based lateral flow-type indicator displacement assay for γ-hydroxybutyric acid (GHB) detection in beverages The use of gamma-hydroxybutyric acid (GHB) in drug-facilitated sexual assault has increased due to its availability and high solubility in aqueous solutions and alcoholic beverages, necessitating the development of rapid methods for GHB detection. In this respect, portable testing methods for use in the field, based on lateral flow assays (LFAs) and capable of detecting trace concentrations of target analytes, are particularly attractive and hold enormous potential for the detection of illicit drugs. Using this strategy, here we report a rapid, low cost, easy-to-handle strip-based LFA for GHB analysis employing a smartphone for fluorescence readout. At molecular signalling level, the ensemble is based on a Cu2+ complex with a tetradentate ligand and the fluorescent dye coumarin 343, which indicate GHB through an indicator displacement assay (IDA) in aqueous solution. When incorporated in a LFA-based strip test this system shows a detection limit as low as 0.03 μM for GHB in MES buffer solution and is able to detect GHB at concentrations of 0.1 μM in soft drinks and alcoholic beverages in only 1 min. Amsterdam Elsevier B.V. 2022 Sensors and Actuators: B. Chemical 377 1 7 urn:nbn:de:kobv:b43-564631 10.1016/j.snb.2022.133043 https://creativecommons.org/licenses/by-nc-nd/4.0/deed.de 2022-12-05 OPUS4-54774 Posterpräsentation Hülagü, Deniz; Tobias, Charlie; Gojani, Ardian B.; Rurack, Knut; Hodoroaba, Vasile-Dan Towards automated scanning electron microscopy image analysis of core-shell microparticles for quasi-3D determination of the surface roughness Core-shell (CS) particles have been increasingly used for a wide range of applications due to their unique properties by merging individual characteristics of the core and the shell materials. The functionality of the designed particles is strongly influenced by their surface roughness. Quantitative evaluation of the roughness of CS microparticles is, however, a challenging task for Scanning Electron Microscopy (SEM). The SEM images contain two-dimensional (2D) information providing contour roughness data only from the projection of the particle in the horizontal plane. This study presents a practical procedure to achieve more information by tilting the sample holder, hence allowing images of different areas of a single particle to be recorded at different orientations under the same view angle. From the analysis of these images, quasi three-dimensional (3D) information is obtained. Three types of home-made particles were investigated: i) bare polystyrene (PS) particles, ii) PS particles decorated with a first magnetic iron oxide (Fe3O4) nanoparticle shell forming CS microbeads, iii) PS/Fe3O4 particles closed with a second silica (SiO2) shell forming core-shell-shell (CSS) microbeads. A series images of a single particle were taken with stepwise tilted sample holder up to 10° by an SEM with high-resolution and surface sensitive SE-InLens® mode. A reliable analysis tool has been developed by a script in Python to analyze SEM images automatically and to evaluate profile roughness quantitatively, for individual core-shell microparticles. Image analysis consists of segmentation of the images, identifying contour and the centre of the particle, and extracting the root mean squared roughness value (RMS-RQ) of the contour profile from the particle projection within a few seconds. The variation in roughness from batch-to-batch was determined with the purpose to set the method as a routine quality check procedure. Flow cytometry measurements provided complementary data. Measurement uncertainties associated to various particle orientations were also estimated. 2022 ICASS 5th International Conference on Applied Surface Science Palma, Mallorca, Spain 25.04.2022 28.05.2022 2022-05-09 OPUS4-56310 Zeitschriftenartikel Jiang, Shan; Wang, T.; Behren, S.; Westerlind, U.; Gawlitza, Kornelia; Persson, J. L.; Rurack, Knut Sialyl-Tn Antigen-Imprinted Dual Fluorescent Core-Shell Nanoparticles for Ratiometric Sialyl-Tn Antigen Detection and Dual-Color Labeling of Cancer Cells Sialyl-Tn (STn or sialyl-Thomsen-nouveau) is a carbohydrate antigen expressed by more than 80% of human carcinomas. We here report a strategy for ratiometric STn detection and dual-color cancer cell labeling, particularly, by molecularly imprinted polymers (MIPs). Imprinting was based on spectroscopic studies of a urea-containing green-fluorescent monomer 1 and STn-Thr-Na (sodium salt of Neu5Acα2-6GalNAcα-O-Thr). A few-nanometer-thin green-fluorescent polymer shell, in which STn-Thr-Na was imprinted with 1, other comonomers, and a cross-linker, was synthesized from the surface of red-emissive carbon nanodot (R-CND)-doped silica nanoparticles, resulting in dual fluorescent STn-MIPs. Dual-color labeling of cancer cells was achieved since both red and green emissions were detected in two separate channels of the microscope and an improved accuracy was obtained in comparison with single-signal MIPs. The flow cytometric cell analysis showed that the binding of STn-MIPs was significantly higher (p < 0.001) than that of non-imprinted polymer (NIP) control particles within the same cell line, allowing to distinguish populations. Based on the modularity of the luminescent core-fluorescent MIP shell architecture, the concept can be transferred in a straightforward manner to other target analytes. ACS Publications 2022 ACS Applied Nano Materials 1 14 urn:nbn:de:kobv:b43-563106 10.1021/acsanm.2c03252 https://creativecommons.org/licenses/by-nc-nd/4.0/deed.de 2022-11-21 OPUS4-54502 Zeitschriftenartikel Valderrey, Virginia; Gawlitza, Kornelia; Rurack, Knut Thiourea- and Amino-Substituted Benzoxadiazole Dyes with Large Stokes Shifts as Red-Emitting Probe Monomers for Imprinted Polymer Layers Targeting Carboxylate-Containing Antibiotics Bifunctional fluorescent molecular oxoanion probes based on the benzoxadiazole (BD) chromophore are described which integrate a thiourea binding motif and a polymerizable 2-aminoethyl methacrylate unit in the 4,7-positions of the BD core. Concerted charge transfer in this electron donor-acceptor-donor architecture endows the dyes with strongly Stokes shifted (up to >250 nm) absorption and fluorescence. Binding of electron-rich carboxylate guests at the thiourea receptor leads to further analyte-induced red-shifts of the emission, shifting the fluorescence maximum of the complexes to ≥700 nm. Association constants for acetate are ranging from 1-5×105 M−1 in acetonitrile. Integration of one of the fluorescent probes through its polymerizable moiety into molecularly imprinted polymers (MIPs) grafted from the surface of submicron silica cores yielded fluorescent MIP-coated particle probes for the selective detection of antibiotics containing aliphatic carboxylate groups such as enoxacin (ENOX) at micromolar concentrations in highly polar solvents like acetonitrile. Wiley-VCH 2022 Thiourea- and Amino-Substituted Benzoxadiazole Dyes with Large Stokes Shifts as Red-Emitting Probe Monomers for Imprinted Polymer Layers Targeting Carboxylate-Containing Antibiotics 1 9 urn:nbn:de:kobv:b43-545027 10.1002/chem.202104525 https://creativecommons.org/licenses/by/4.0/deed.de 2022-03-21 OPUS4-54662 Zeitschriftenartikel Beyer, S.; Kimani, Martha Wamaitha; Zhang, Y.; Verhassel, A.; Sternbæk, L.; Wang, T.; Persson, J. L.; Härkönen, P.; Johansson, E.; Caraballo, R.; Elofsson, M.; Gawlitza, Kornelia; Rurack, Knut; Ohlsson, L.; El-Schich, Z.; Gjörloff Wingren, A.; Stollenwerk, M. M. Fluorescent Molecularly Imprinted Polymer Layers against Sialic Acid on Silica-coated Polystyrene Cores - Assessment of the Binding Behavior to Cancer Cells Sialic acid (SA) is a monosaccharide usually linked to the terminus of glycan chains on the cell surface. It plays a crucial role in many biological processes, and hypersialylation is a common feature in cancer. Lectins are widely used to analyze the cell surface expression of SA. However, these protein molecules are usually expensive and easily denatured, which calls for the development of alternative glycan-specific receptors and cell imaging technologies. In this study, SA-imprinted fluorescent core-shell molecularly imprinted polymer particles (SA-MIPs) were employed to recognize SA on the cell surface of cancer cell lines. The SA-MIPs improved suspensibility and scattering properties compared with previously used core-shell SA-MIPs. Although SA-imprinting was performed using SA without preference for the alpha-2,3- and alpha-2,6-SA forms, we screened the cancer cell lines analyzed using the lectins Maackia Amurensis Lectin I (MAL I, alpha-2,3-SA) and Sambucus Nigra Lectin (SNA, alpha-2,6-SA). Our results show that the selected cancer cell lines in this study presented a varied binding behavior with the SA-MIPs. The binding pattern of the lectins was also demonstrated. Moreover, two different pentavalent SA conjugates were used to inhibit the binding of the SA-MIPs to breast, skin, and lung cancer cell lines, demonstrating the specificity of the SA-MIPs in both flow cytometry and confocal fluorescence microscopy. We concluded that the synthesized SA-MIPs might be a powerful future tool in the diagnostic analysis of various cancer cells. Basel MDPI 2022 Cancers 14 8 urn:nbn:de:kobv:b43-546625 110.3390/cancers14081875 https://creativecommons.org/licenses/by/4.0/deed.de 2022-04-20 OPUS4-54176 Zeitschriftenartikel Climent Terol, Estela; Weller, Michael G.; Martínez-Mánez, R.; Rurack, Knut Immunochemical design of antibody-gated indicator delivery (gAID) systems based on mesoporous silica nanoparticles In this work, the optimization of the immunochemical response of antibody-gated indicator delivery (gAID) systems prepared with mesoporous silica nanoparticles has been studied along various lines of system tailoring, targeting the peroxide-type explosive TATP as an exemplary analyte. The mechanism of detection of these gAID systems relies on a displacement of an antibody "cap" bound to hapten derivatives anchored to the surface of a porous hybrid material, allowing the indicator cargo stored in the mesopores to escape and massively amplify the analyte-related signal. Since our aim was to obtain gAID systems with the best possible response in terms of sensitivity, selectivity, and assay time, sera obtained from different immunization boosts were screened, the influence of auxiliary reagents was assessed, structural hapten modification (hapten heterology) was investigated, and various indicator dyes and host materials were tested. Considering that highly selective and sensitive immunological responses are best obtained with high-affinity antibodies which, however, could possess rather slow dissociation constants, leading to slow responses, the main challenge was to optimize the immunochemical recognition system for a rapid response while maintaining a high sensitivity and selectivity. The best performance was observed by grafting a slightly mismatching (heterologous) hapten to the surface of the nanoparticles in combination with high-affinity antibodies as "caps", yielding for the first time gAID nanomaterials for which the response time could be improved from hours to <5 min. The materials showed favorable detection limits in the lower ppb range and discriminated TATP well against H2O2 and other explosives. Further optimization led to straightforward integration of the materials into a lateral flow assay without further treatment or conditioning of the test strips while still guaranteeing remarkably fast overall assay times. Washington, DC American Chemical Society 2022 ACS applied nano materials 5 1 626 641 10.1021/acsanm.1c03417 2022-01-03 OPUS4-54444 Zeitschriftenartikel Kimani, Martha Wamaitha; Pérez-Padilla, Victor; Valderrey, Virginia; Gawlitza, Kornelia; Rurack, Knut Red-Emitting Polymerizable Guanidinium Dyes as Fluorescent Probes in Molecularly Imprinted Polymers for Glyphosate Detection The development of methodologies to sense glyphosate has gained momentum due to its toxicological and ecotoxicological effects. In this work, a red-emitting and polymerizable guanidinium benzoxadiazole probe was developed for the fluorescence detection of glyphosate. The interaction of the fluorescent probe and the tetrabutylammonium salt of glyphosate was studied via UV/vis absorption and fluorescence spectroscopy in chloroform and acetonitrile. The selective recognition of glyphosate was achieved by preparing molecularly imprinted polymers, able to discriminate against other common herbicides such as 2,4-dichlorophenoxyacetic acid (2,4-D) and 3,6-dichloro-2-methoxybenzoic acid (dicamba), as thin layers on submicron silica particles. The limits of detection of 4.8 µM and 0.6 µM were obtained for the sensing of glyphosate in chloroform and acetonitrile, respectively. The reported system shows promise for future application in the sensing of glyphosate through further optimization of the dye and the implementation of a biphasic assay with water/organic solvent mixtures for sensing in aqueous environmental samples. Basel MDPI 2022 Chemosensors 10 3 1 20 urn:nbn:de:kobv:b43-544441 10.3390/chemosensors10030099 https://creativecommons.org/licenses/by/4.0/deed.de 2022-03-10 OPUS4-54257 Zeitschriftenartikel Hülagü, Deniz; Tobias, Charlie; Climent Terol, Estela; Gojani, Ardian; Rurack, Knut; Hodoroaba, Vasile-Dan Generalized Analysis Approach of the Profile Roughness by Electron Microscopy with the Example of Hierarchically Grown Polystyrene-Iron Oxide-Silica Core-Shell-Shell Particles The roughness as a property of core-shell (CS) microparticles plays a key role in their functionality. Quantitative evaluation of the roughness of CS microparticles is, however, a challenging task with approaches using electron microscopy images being scarce and showing pronounced differences in terms of methodology and results. This work presents a generalized method for the reliable roughness determination of nonplanar specimens such as CS particles from electron microscopic images, the method being robust and reproducible with a high accuracy. It involves a self-written software package (Python) that analyzes the recorded images, extracts corresponding data, and calculates the roughness based on the deviation of the identified contour. Images of single particles are taken by a dual mode scanning electron microscopy (SEM) setup which permits imaging of the same field-of-view of the sample with high resolution and surface sensitive in SE InLens mode as well as in transmission mode (TSEM). Herein, a new type of polystyrene core-iron oxide shell-silica shell particles is developed to serve as a set of lower micrometer-sized study objects with different surface roughness; the analysis of their images by the semiautomatic workflow is demonstrating that the particles' profile roughness can be quantitatively obtained. Wiley-VCH 2022 Advanced Engineering Materials 1 9 urn:nbn:de:kobv:b43-542576 10.1002/adem.202101344 https://creativecommons.org/licenses/by/4.0/deed.de 2022-01-27 OPUS4-54004 Zeitschriftenartikel Hudson, A.D.; Jamieson, O.; Crapnell, R.D.; Rurack, Knut; Soares, T.C.C.; Mecozzi, F.; Laude, A.; Gruber, J.; Novakovic, K.; Peeters, M. Dual detection of nafcillin using a molecularly imprinted polymer-based platform coupled to thermal and fluorescence read-out Reported here is the production of molecularly imprinted polymer (MIP) films, integrating a fluorescent moiety that serves as both an element for template interaction and signalling, for the thermal and optical detection of the beta-lactam antibiotic nafcillin. Fluorescein methacrylate (FluMa) was synthesized and introduced during the molecular imprinting process as the sole monomer and in a 1 : 1 mixture with methacrylic acid (MAA), allowing to draw first conclusions on the MIP formation potential of such a rather large and rigid monomer. At first, MIP microparticles containing FluMa were prepared by free radical polymerisation. Optical batch rebinding experiments revealed that FluMa can act as a functional monomer for selective detection of nafcillin; however, the addition of MAA as co-monomer significantly improved performance. Subsequently, thin MIP films containing FluMa were deposited onto functionalised glass slides and the influence of porogen, drying time, and monomer composition was studied. These MIP-functionalised glass electrodes were mounted into a customised 3D-printed flow cell, where changes in the liquid were either evaluated with a thermal device or using fluorescence bright field microscopy. Thermal analysis demonstrated that multiple MIP layers enhanced sensor specificity, with detection in the environmentally relevant range. The fluorescence bright field microscope investigations validated these results, showing an increase in the fluorescence intensity upon exposure of the MIP-functionalised glass slides to nafcillin solutions. These are promising results for developing a portable sensor device that can be deployed for antibiotics outside of a dedicated laboratory environment, especially if sensor design and fluorophore architecture are optimised. Cambridge Royal Society of Chemistry 2021 Materials Advances 2 15 5105 5115 urn:nbn:de:kobv:b43-540044 10.1039/D1MA00192B https://creativecommons.org/licenses/by-nc/4.0/deed.de 2021-12-13 OPUS4-54020 Zeitschriftenartikel Climent Terol, Estela; Rurack, Knut Streifenschnelltest mit ppt-Empfindlichkeit durch Kombination von Elektrochemilumineszenz-Detektion mit Aptamer-gesteuerter Indikatorfreisetzung aus mesoporösen Nanopartikeln Die Kombination aus elektrogenerierter Chemilumineszenz (ECL) und Aptamer-gesteuerter Indikatorfreisetzung (gAID) aus magnetischen mesoporösen Silica-Nanopartikeln, die in mit Poly(ethylenglycol) und N-(3-Triethoxysilylpropyl) diethanolamin funktionalisiertes Glasfaserpapier eingebettet sind, ermöglichte die Entwicklung eines Schnelltests, mit dem sich Penicillin direkt in verdünnter Milch bis auf 50 +/- 9 ppt in <5 min nachweisen lässt. Die kovalente Bindung der Aptamer-Kappe an das Siliciumdioxid-Gerüst ermöglichte den Verschluss der Poren durch nicht-kovalente elektrostatische Wechselwirkungen mit Oberflächen-Aminogruppen. Die Bindung von Penicillin führte zu einer Faltung des Aptamers, wodurch der zuvor in das Material geladene ECL-Reporter Ru(bpy)32+ freigesetzt wurde und nach lateralem Fluss von einer Smartphone-Kamera nach elektrochemischer Anregung mit einer in einen 3D-gedruckten Halter eingesetzten Siebdruckelektrode detektiert wird. Der Ansatz ist einfach, generisch und bietet Vorteile hinsichtlich Empfindlichkeit, Messunsicherheit und Robustheit gegenüber konventioneller Fluoreszenz- oder elektrochemischer Detektion, insbesondere für Point-of-Need-Analysen anspruchsvoller Matrices und Analyten im Ultraspurenbereich. Weinheim Wiley-VCH 2021 Angewandte Chemie 133 50 26491 26501 urn:nbn:de:kobv:b43-540205 10.1002/ange.202110744 https://creativecommons.org/licenses/by/4.0/deed.de 2021-12-15 OPUS4-54001 Vortrag Rurack, Knut Reaction-based BODIPY dyes as powerful tools in fluorescence sensing applications The reversible analyte-induced switching between a colourless leuco form of a dye and its coloured all-π-conjugated form is one of the oldest concepts in probe- or indicator-based optical analysis,1 constituting so-called "one-color indicators".2 In contrast to colour changes in the visible region, for which usually a bond-forming or a non-covalent interaction between a functional group on an indicator and an analyte is responsible, the extraordinarily large shifts of 150-250 nm seen for leuco-to-all-π-conjugated transformation are only possible when the reaction takes place directly at a site that is an intrinsic part of a dye's π-system; the classic case are triphenylmethane dyes.3 Despite its obvious potential, this approach has not been a very popular area of scientific research for decades, perhaps because it is much more difficult to implement selectivity than by modifying terminal functional groups. However, in recent years, reaction-based fluorescence probes have attracted increasing attention by virtue of their superior sensitivity.4,5 Nowadays, rhodamines and fluoresceins are by far the most prominent groups of reaction-based indicators.5 They are usually switched between a colourless and non-fluorescent and a greenish-yellowish absorbing and yellowish-reddish emitting form. Typically, the coloured and fluorescent form is ionic, while the colourless form is neutral, reactions having mainly be designed to occur at the end groups of the xanthenoid π-system. BODIPY dyes, with their favourable spectroscopic and chemical properties as well as facile wavelength tunability features have only very recently been explored into this direction.6,7 Reaction at the core dipyrrin framework of these dyes led to strong colour and fluorescence modulations with potential applications in materials sciences6 and cell imaging.7 The present contribution will highlight the mechanisms at play and the sensing performance realized so far, and will compare core-reactive approaches to reaction-based signalling that involves π-extension of BODIPYs.8,9 2021 11th International Conference on Porphyrins and Phthalocyanines (ICPP-11) Online meeting 26.06.2021 02.07.2021 2021-12-13 OPUS4-54002 Vortrag Rurack, Knut Approaches to Sensitive and Multiplexed Assays for Robust, Reliable and User-friendly Point-of-Need Analysis Analytical assays that can be used outside of a dedicated laboratory environment have received unprecedented attention all around the globe during the last one and a half years, in which the world was struggling with and trying to contain the SARS-CoV-2 pandemic. However, besides their current prominence in the field of medical diagnostics, rapid tests and assays have also become increasingly important in other areas ranging from food and feed via security and forensics to environmental management. The advantage is obvious: taking the assay to the sample instead of bringing the sample to the laboratory minimizes the time between first suspicion and first decision taking. Especially today, where mobile communication devices with powerful computing capabilities and onboard cameras are omnipresent, the majority of the global population possesses the basic skills of operating a powerful detector, ready at their fingertips. The stage is thus set for a much broader use of analytical measurements in terms of prognostics and prevention. Today, however, tests for single parameters are still prevailing, whether it is a SARS-CoV-2 biomarker, the glucose level in blood or the concentration of lead in a water sample. Also, for industrial use, many mobile analytical systems still target a single parameter, and several separate runs or tests have to be used even if one wants to screen for only a small number of key parameters. Current challenges in the field thus lie with the development of low-number multiplexing strategies while allowing for robust, reliable, fast, and user-friendly operation and while still reaching the required sensitivities. This lecture will give an overview of various generic approaches developed in BAM's Chemical and Optical Sensing Division over the years to address these challenges. In particular, it will highlight how the combination of supramolecular (bio)chemistry, luminescence detection, hybrid (nano)materials and device miniaturization can result in powerful (bio)analytical assays that can be used at a point-of-need. Selected examples will introduce key aspects of such systems like tailored signaling mechanisms and recognition elements, materials functionalization and device integration, including hybrid mesoporous nanomaterials, gated indicator release systems, molecularly imprinted polymers, microfluidic devices, test strips and smartphone-based analysis. 2021 Advanced Analytical Technologies Seminar Online meeting 08.12.2021 08.12.2021 2021-12-13 OPUS4-54003 Zeitschriftenartikel Weller, Michael G.; Schneider, Rudolf; Rurack, Knut Mit dem Testsystem zur Probe (Bio)chemische Sensoren ersetzen bei der Vor-Ort-Analytik die großen Messgeräte oder dienen dazu, Analyten im Verdachtsfall oder kontinuierlich zu überwachen. Das können pharmazeutische Stoffe im Abwasser sein, Aflatoxin in Milch oder Sprengstoff am Flughafen. Ein Überblick über Neuentwicklungen. Weinheim Wiley-VCH GDCh 2021 Nachrichten aus der Chemie 69 10 71 74 10.1002/nadc.20214112170 2021-12-13 OPUS4-53123 Zeitschriftenartikel Hülagü, Deniz; Tobias, Charlie; Gojani, Ardian; Rurack, Knut; Hodoroaba, Vasile-Dan Analysis of the profile roughness of core-shell microparticles by electron microscopy A particle roughness analysis tool, based on electron microscopy images (SEM and TEM). The influence of various parameters on the calculated roughness was also investigated: the setting of the proper threshold, accelerating voltage, etc. The samples were gradually tilted to extend imaging information of more than only one projection. Furthermore, the measurement uncertainty of the profile roughness of particles associated to various orientations was estimated. Cambridge University Press 2021 Microscopy and Microanalysis 27 Suppl. 1 2002 2004 10.1017/S1431927621007285 2021-08-23 OPUS4-53515 Zeitschriftenartikel Maher, C.; Schazmann, B.; Gornushkin, Igor B.; Rurack, Knut; Gojani, Ardian Exploring an Application of Principal Component Analysis to LaserInduced Breakdown Spectroscopy of Stainless-Steel Standard Samples as a Research Project Laser-induced breakdown spectroscopy (LIBS) and principal component analysis (PCA) are frequently used for analytical purposes in research and industry, but they seldom are part of the chemistry Curriculum or laboratory exercises. This case study paper describes the combined application of LIBS and PCA during a research internship for an undergraduate student. The instructional method applied was based on a one-on-one mentorship, in which case the learner was engaged in a Research work. The learning activities included theoretical introductions to the LIBS and PCA methods, numerical simulation, experiments, and data analysis. The study covered three main topics: analysis of LIBS spectra, application of PCA for clustering, and use of PCA for experimental design. The realization of the study was instructive for all parties involved: from the mentorship point of view, it is concluded that the topics can be covered during an internship or developed into a one semester long research-based module of a chemistry program or a final year project. The student, on the other hand, developed profound technical skills in performing experiments and using PCA software for data analysis. USA American Chemical Society Publications 2021 Journal of Chemical Education 98 3237 3244 10.1021/acs.jchemed.1c00563 2021-10-14 OPUS4-52259 Zeitschriftenartikel Climent Terol, Estela; Rurack, Knut; Hecht, Mandy Loading and Release of Charged and Neutral Fluorescent Dyes into and from Mesoporous Materials: A Key Role for Sensing Applications The aim of this study is to determine the efficiency of loading and release of several zwitterionic, neutral, anionic and cationic dyes into/from mesoporous nanoparticles to find the optimum loading and release conditions for their application in detection protocols. The loading is carried out for MCM-41 type silica supports suspended in phosphate-buffered saline (PBS) buffer (pH 7.4) or in acetonitrile, involving the dyes (rhodamine B chloride, rhodamine 101 chloride, rhodamine 101 perchlorate, rhodamine 101 inner salt, meso-(4-hydroxyphenyl)-boron-dipyrromethene (BODIPY), sulforhodamine B sodium salt and fluorescein 27). As a general trend, rhodamine-based dyes are loaded with higher efficiency, when compared with BODIPY and fluorescein dyes. Between the rhodamine-based dyes, their charge and the solvent in which the loading process is carried out play important roles for the amount of cargo that can be loaded into the materials. The delivery experiments carried out in PBS buffer at pH 7.4 reveal for all the materials that anionic dyes are more efficiently released compared to their neutral or cationic counterparts. The overall best performance is achieved with the negatively charged sulforhodamine B dye in acetonitrile. This material also shows a high delivery degree in PBS buffer. MDPI 2021 Micromachines 12 3 249 urn:nbn:de:kobv:b43-522596 10.3390/mi12030249 https://creativecommons.org/licenses/by/4.0/deed.de 2021-03-15 OPUS4-53447 Zeitschriftenartikel Climent Terol, Estela; Rurack, Knut Combining electrochemiluminescence detection with aptamer-gated indicator releasing mesoporous nanoparticles enables ppt sensitivity for strip-based rapid tests The combination of electrogenerated chemiluminescence (ECL) and aptamer-gated indicator delivering (gAID) magnetic mesoporous silica nanoparticles embedded into glass fibre paper functionalised with poly(ethyleneglycol) and N-(3-triethoxysilylpropyl)diethanolamine allowed the development of a rapid test that detects penicillin directly in diluted milk down to 50 ± 9 ppt in <5 min. Covalent attachment of the aptamer 'cap' to the silica scaffold enabled pore closure through non-covalent electrostatic interactions with surface amino groups, while binding of penicillin led to a folding-up of the aptamer thus releasing the ECL reporter Ru(bpy)32+ previously loaded into the material and letting it be detected after lateral flow by a smartphone camera upon electrochemical excitation with a screen printed electrode inserted into a 3D-printed holder. The approach is simple, generic and presents advantages with respect to sensitivity, measurement uncertainty and robustness compared with conventional fluorescence or electrochemical detection, especially for point-of-need analyses of challenging matrices and analytes at ultra-trace levels. Weinheim Wiley-VCH 2021 Angewandte Chemie - International Edition 1 11 10.1002/anie.202110744 2021-10-06 OPUS4-52576 Beitrag zu einem Tagungsband Gawlitza, Kornelia; Johann, Sergej; Mansurova, Maria; Kohlhoff, Harald; Tiebe, Carlo; Bell, Jérémy; Bartholmai, Matthias; Rurack, Knut Semi-automatic Measurement Device for Long-Term Monitoring of Ammonia in Gas Phase In the present paper the development of a semi-automated device for long-term monitoring of gaseous ammonia is described. A sensor material was produced that changes its optical properties in the pres-ence of low concentrations of ammonia in air. The implementation into an electronic device enables precise, simple, economic and fast monitoring of low concentrations of harmful gases, like ammonia, and hence can help to improve the climate monitoring in livestock housing, barns or stables. 2021 SMSI 2021 Proceedings SMSI 2021 Online meeting 03.05.2021 06.05.2021 133 134 2021-05-06 OPUS4-53336 Zeitschriftenartikel Jiang, Shan; Gawlitza, Kornelia; Rurack, Knut Dual-Fluorescent Nanoparticle Probes Consisting of a Carbon Nanodot Core and a Molecularly Imprinted Polymer Shell Dual-fluorescent molecularly imprinted nanoparticles with a red-emissive carbon nanodot-doped silica core and a chlorogenic acid-imprinted fluorescent polymer layer are prepared and their use in ratiometric fluorometric analysis is described. Nanoparticle probes consisting of a shielded and stably emitting core and a shell with embedded binding sites that indicates the presence of an analyte with a change in emission allow for internally referenced measurements potentially accounting for detrimental influences from instrument drifts, light source fluctuations or sensor materials-related inhomogeneities. Humana, New York, NY Springer 2021 Methods in Molecular Biology 2359 195 208 10.1007/978-1-0716-1629-1_17 2021-09-23 OPUS4-53283 Zeitschriftenartikel Gojani, Ardian; Tobias, Charlie; Hülagü, Deniz; Rurack, Knut; Hodoroaba, Vasile-Dan Toward determination of the surface roughness of particles from a SEM image In this communication, we address the issue of roughness measurement by investigating if the grayscale values from SEM images can be used for surface roughness determination of spherical particles. New York, NY Cambridge University Press Microscopy Society of America 2021 Microscopy and microanalysis 27 Suplement S1 3302 3305 10.1017/S1431927621011375 2021-09-17 OPUS4-55787 Zeitschriftenartikel Climent Terol, Estela; Wan, Wei; Rurack, Knut Toward Label-Free Optical Multiplexing of Analytes in Indicator Release Lateral Flow Assays via Detection Zones Containing Tailored Capture Materials The use of macromolecules and materials immobilized in the detection zone of test strips for indicator capture and focusing in label-free lateral flow assays (LFAs) is described, with emphasis on its future use in low number multiplexing. Several materials such as polyelectrolytes, functionalized mesoporous silica micro- and nanoparticles, chemically modified cellulose or glass fibre (GF) membranes and molecularly imprinted polymer gels coated onto membranes were studied in model assays, before the most promising materials were combined with antibody-gated indicator delivering (gAID) sensor materials. Cellulose, nitrocellulose and GF membranes were used as supports and highly fluorescent dyes of different charge states as model indicators. Combination of the best performing capture materials with gAID systems made it possible to distinctly increase the sensitivity and reduce the measurement uncertainty in the LFA testing of pentaerythritol tetranitrate (PETN) in aqueous samples. In addition, dual-plexing of PETN and 2,4,6-trinitrotoluene (TNT) was realized on a single test strip containing two dedicated capture zones. Weinheim Wiley-VCH 2022 Analysis & Sensing 2 4 1 10 urn:nbn:de:kobv:b43-557873 10.1002/anse.202100062 https://creativecommons.org/licenses/by-nc/4.0/deed.de 2022-09-21 OPUS4-55528 Zeitschriftenartikel Kimani, Martha Wamaitha; Kislenko, Evgeniia; Gawlitza, Kornelia; Rurack, Knut Fluorescent molecularly imprinted polymer particles for glyphosate detection using phase transfer agents In this work, molecular imprinting was combined with direct fluorescence detection of the pesticide Glyphosate (GPS). Firstly, the solubility of highly polar GPS in organic solvents was improved by using lipophilic tetrabutylammonium (TBA+) and tetrahexylammonium (THA+) counterions. Secondly, to achieve fluorescence detection, a fluorescent crosslinker containing urea-binding motifs was used as a probe for GPS-TBA and GPS-THA salts in chloroform, generating stable complexes through hydrogen bond formation. The GPS/fluorescent dye complexes were imprinted into 2-3 nm fluorescent molecularly imprinted polymer (MIP) shells on the surface of sub-micron silica particles using chloroform as porogen. Thus, the MIP binding behavior could be easily evaluated by fluorescence titrations in suspension to monitor the spectral changes upon addition of the GPS analytes. While MIPs prepared with GPS-TBA and GPS-THA both displayed satisfactory imprinting following titration with the corresponding analytes in chloroform, GPS-THA MIPs displayed better selectivity against competing molecules. Moreover, the THA+ counterion was found to be a more powerful phase transfer agent than TBA+ in a biphasic assay, enabling the direct fluorescence detection and quantification of GPS in water. A limit of detection of 1.45 μM and a linear range of 5-55 μM were obtained, which match well with WHO guidelines for the acceptable daily intake of GPS in water (5.32 μM). London Macmillan Publishers Limited 2022 Scientific reports 12 1 1 15 urn:nbn:de:kobv:b43-555281 10.1038/s41598-022-16825-9 https://creativecommons.org/licenses/by/4.0/deed.de 2022-08-23 OPUS4-55373 Zeitschriftenartikel Hülagü, Deniz; Tobias, Charlie; Gojani, Ardian B.; Rurack, Knut; Hodoroaba, Vasile-Dan From 2D and Single Particle to 3D and Batch Analysis as a Routine Quality Check Procedure for the Morphological Characterization of Core-Shell Microparticles CS particles show unique properties by merging individual characteristics of the core and the shell materials. An alteration particularly in their surface roughness affects the final performance of the particles in the targeted application. Quantitative evaluation of the roughness of CS microparticles is, however, a challenging task employing microscopic techniques being scarce and showing large differences in terms of methodology and results. In our previous work, we have reported a systematic study with a reliable analysis tool, which evaluates profile roughness quantitatively, for individual core-shell microparticles using electron microscopy (EM) images of both types, Scanning Electron Microscopy (SEM) and transmission mode SEM (or TSEM). The SEM images contain two-dimensional (2D) information, therefore, provide profile roughness data only from the projection in the horizontal plane (in other words, from the "belly") of a spherical particle. The present study offers a practical procedure to give access to more information by tilting the sample holder and hence allowing images of a single particle to be recorded at different orientations under the same view angle. From the analysis of these images, extended information on surface roughness of the particle can be extracted. Thus, instead of obtaining 2D information from a single SEM image, three-dimensional (3D) information is obtained from 2D projections recorded at different particle orientations. Cambridge University Press 2022 Microscopy and Microanalysis 28 Microscopy and Microanalysis 2022 Oregon, Portland, USA 31.07.2022 04.08.2022 S1 332 334 10.1017/S1431927622002094 2022-07-27 OPUS4-55744 Zeitschriftenartikel Garrido, E.; Climent Terol, Estela; Marcos, M. D.; Sancenón, F.; Rurack, Knut; Martínez-Máñez, R. Dualplex lateral flow assay for simultaneous scopolamine and "cannibal drug" detection based on receptor-gated mesoporous nanoparticles We report herein the design of a strip-based rapid test utilizing bioinspired hybrid nanomaterials for the in situ and at site detection of the drug scopolamine (SCP) using a smartphone for readout, allowing SCP identification in diluted saliva down to 40 nM in less than 15 min. For this purpose, we prepared a nanosensor based on mesoporous silica nanoparticles loaded with a fluorescent reporter (rhodamine B) and functionalized with bethanechol, a potent agonist of recombinant human muscarinic acetylcholine receptor M2 (M2-AChR). M2-AChR interaction with the anchored bethanechol derivative leads to capping of the pores. The sensing mechanism relies on binding of SCP to M2-AChR resulting in pore opening and delivery of the entrapped rhodamine B reporter. Moreover, the material was incorporated into strips for lateral-flow assays coupled to smartphone readout, giving fast response time, good selectivity, and exceptional sensitivity. In an attempt to a mobile analytical test system for law enforcement services, we have also developed a dualplex lateral flow assay for SCP and 3,4-methylenedioxypyrovalerone (MDPV) also known as the so-called "cannibal drug". Cambridge Royal Society of Chemistry 2022 Nanoscale 1 9 10.1039/d2nr03325a 2022-09-19 OPUS4-37063 Zeitschriftenartikel Climent Terol, Estela; Biyikal, Mustafa; Gawlitza, Kornelia; Dropa, T.; Urban, M.; Costero, A. M.; Martínez-Mánez, Ramon; Rurack, Knut A rapid and sensitive strip-based quick test for nerve agents Tabun, Sarin, and Soman using BODIPY-modified silica materials Test strips that in combination with a portable fluorescence reader or digital camera can rapidly and selectively detect chemical warfare agents (CWAs) such as Tabun (GA), Sarin (GB), and Soman (GD) and their simulants in the gas phase have been developed. The strips contain spots of a hybrid indicator material consisting of a fluorescent BODIPY indicator covalently anchored into the channels of mesoporous SBA silica microparticles. The fluorescence quenching response allows the sensitive detection of CWAs in the μg m−3 range in a few seconds. Online Library Wiley 2016 Chemistry - a European journal 22 32 11138 11142 10.1002/chem.201601269 2016-08-04 OPUS4-30786 Vortrag Rurack, Knut Sensory Molecularly Imprinted Polymers for the Selective Detection of Carboxylates through Fluorescence Modulation 2014 Europt(r)ode XII Europt(r)ode XII Athens, Greece 2014-04-13 2014-04-16 2016-02-20 OPUS4-30787 Posterpräsentation Rurack, Knut Reference-free total reflection X-ray fluorescence analysis for surface functional group quantification of funtional groups on surfaces for bio-analytical applications 2014 E-MRS 2014 Spring Meeting E-MRS 2014 Spring Meeting Lille, France 2014-05-26 2014-05-30 2016-02-20 OPUS4-31354 Vortrag Rurack, Knut Fluorescent MIP (Molecularly Imprinted Polymer) Sensor Materials 2014 1st International Caparica Conference on Chromogenic and Emissive Materials 1st International Caparica Conference on Chromogenic and Emissive Materials Lisbon, Portugal 2014-09-08 2014-09-10 2016-02-20 OPUS4-31307 Vortrag Rurack, Knut How to Integrate Fluorescent Probes with Molecularly Imprinted Polymers of Potent Fluorogenic Sensor Materials 2014 VIII Workshop on Sensors and Molecular Recognition VIII Workshop on Sensors and Molecular Recognition Valencia, Spain 2014-07-03 2014-07-04 2016-02-20 OPUS4-30518 Vortrag Rurack, Knut Integrating Dyes with Sensing Matrices: Toward Simple yet Powerful Fluorescence Assays 2014 Gastvortrag, Department of Biomedical Sciences, Malmö University Gastvortrag, Department of Biomedical Sciences, Malmö University Malmö, Sweden 2014-04-02 2014-04-02 2016-02-20 OPUS4-32012 Zeitschriftenartikel Ritter, B.; Krahl, T.; Rurack, Knut; Kemnitz, E. Nanoscale CaF2 doped with Eu3+ and Tb3+ through fluorolytic sol-gel synthesis In this article, the high potential of the fluorolytic sol-gel process to synthesize nanoscopic rare earth-doped calcium fluoride sols is shown. Through a fluorolytic sol-gel process we manage to achieve spherical monodisperse ~5 nm sized nanoparticles using a simple and reproducible one-pot-wet chemical route at room temperature. The as-synthesized clear sols exhibit an intense red and green luminescence under UV excitation at room temperature. A spectroscopic study of the sols revealed the characteristic transitions 5D0 → 7FJ of Eu3+ and 5D4 → 7FJ of Tb3+, with 5D0 → 7F2 (611 nm) of Eu3+ and 5D4 → 7F4 (581 nm) of Tb3+ as the most prominent transitions. This facile synthetic strategy is also valuable for developing other luminescent nanoparticles. Cambridge Royal Soc. of Chemistry 2014 Journal of materials chemistry C 2 40 8607 8613 urn:nbn:de:kobv:b43-320120 10.1039/c4tc01073f http://creativecommons.org/licenses/by-nc/3.0/de/deed.de 2016-02-20 OPUS4-32013 Zeitschriftenartikel Ashokkumar, Pichandi; Rurack, Knut Fluor on Tour - Schnelltests für die Fluorid-Bestimmung in Wasser Fluorid-Zusatz zum Trinkwasser oder Zahncreme ist weit verbreitet und dient vor allem der Zahngesundheit und als vorbeugende Maßnahme gegen Knochenkrankheiten. Doch eine zu hohe Konzentration an Fluorid kann zu gesundheitlichen Problemen führen. Der hier in diesem Artikel vorgestellte Farbschnelltest kann helfen, die Fluoridkonzentration leichter festzustellen. Darmstadt GIT-Verlag 2014 GIT : Labor-Fachzeitschrift 7 30 33 2016-02-20 OPUS4-31936 Zeitschriftenartikel Ashokkumar, Pichandi; Weißhoff, Hardy; Kraus, Werner; Rurack, Knut Test-strip-based fluorometric detection of fluoride in aqueous media with a BODIPY-linked hydrogen-bonding receptor The measurement of biologically relevant anions, such as fluoride, is an important task in analytical chemistry, in particular, for dental health and osteoporosis. Although a large number of fluoride probes are known, the applicability under relevant conditions is limited to a few examples. To improve this situation, BODIPY-amidothiourea dyes with varying hydrogen-bond donating strengths were developed, the most H-acidic of which (1 c) could detect F- from an inorganic source (NaF) in 50?% aqueous solution (DMSO/water 1:1, v/v) with 0.01 ppm sensitivity through selective fluorescence quenching by a photoinduced electron-transfer (PET) process. Use of the probe and a reference dye with a test-strip assay and a portable and rapidly recording lateral-flow fluorescence reader made determination of F- in neat aqueous solutions, such as spiked water samples and toothpaste extracts, possible in a self-referenced manner, achieving a detection limit of 0.2 ppm. Weinheim Wiley-VCH Gesellschaft Deutscher Chemiker 2014 Angewandte Chemie / International Edition 53 8 2225 2229 10.1002/anie.201307848 2016-02-20 OPUS4-31939 Zeitschriftenartikel Ashokkumar, Pichandi; Weißhoff, Hardy; Kraus, Werner; Rurack, Knut Fluorometrischer Nachweis von Fluorid in wässriger Lösung mittels Teststreifen und einem BODIPY-Wasserstoffbrückenrezeptor-Konjugat Die Bestimmung von biologisch relevanten Anionen wie Fluorid ist eine wichtige Aufgabe in der analytischen Chemie, insbesondere im Hinblick auf Zahnpflege und Osteoporose. Es gibt zwar eine große Zahl an Fluoridsonden, ihre Anwendbarkeit unter umweltrelevanten Bedingungen ist aber auf wenige Beispiele beschränkt. Um dieses Ziel zu erreichen, wurden BODIPY-Amidothioharnstoff-Farbstoffe mit unterschiedlicher Wasserstoffbrückendonorstärke entwickelt, wovon die H-azideste Verbindung (1 c) anorganisches F- (aus NaF) in DMSO/H2O (1:1, v/v) mit 0.01 ppm Empfindlichkeit durch Fluoreszenzlöschung über einen photoinduzierten Elektronentransfer nachweisen kann. Einbettung der Sonde und eines Referenzfarbstoffs in einen Teststreifen-Assay mit einem tragbaren 'Lateral-Flow'-Fluoreszenzlesegerät ermöglichte die Bestimmung von F- in wässrigen Lösungen wie versetzten Wasserproben und Zahncremeextrakten mit interner Referenzierung bis zu einer Nachweisgrenze von 0.2 ppm. Weinheim Wiley-VCH Gesellschaft Deutscher Chemiker 2014 Angewandte Chemie 126 8 2257 2261 10.1002/ange.201307848 2016-02-20 OPUS4-30610 Zeitschriftenartikel Gotor, Raúl; Costero, A. M.; Gil, S.; Gavina, P.; Rurack, Knut On the ion-pair recognition and indication features of a fluorescent heteroditopic host based on a BODIPY core A fluorescent heteroditopic host for ion pairs and zwitterionic species has been synthesized. Its affinity towards a series of anions, cations and ion pairs in acetonitrile has been assessed, and the spectroscopic response has been evaluated. Solid–liquid extraction experiments of inorganic salts, α-amino acids and γ-aminobutyric acid (GABA) into acetonitrile solutions were performed, and the resulting complexes were analyzed by UV/Vis absorption, fluorescence and 1H NMR spectroscopy. The discrimination patterns observed have been rationalized in terms of the molecular topologies of the host and guests. Weinheim Wiley-VCH Verl. 2014 European journal of organic chemistry 2014 19 4005 4013 10.1002/ejoc.201402214 2016-02-20 OPUS4-32135 Zeitschriftenartikel Pascual, L.; Baroja, I.; Aznar, E.; Sancenón, F.; Marcos, M. Dolores; Murguía, J.R.; Amorós, P.; Rurack, Knut; Martínez-Mánez, Ramon Oligonucleotide-capped mesoporous silica nanoparticles as DNA-responsive dye delivery systems for genomic DNA detection New hybrid oligonucleotide-capped mesoporous silica nanoparticles able to detect genomic DNA were designed. Cambridge Royal Society of Chemistry Chemical Society 2015 Chemical communications 51 8 1414 1416 urn:nbn:de:kobv:b43-321357 10.1039/C4CC08306G http://creativecommons.org/licenses/by-nc/3.0/de/deed.de 2016-02-20 OPUS4-32136 Zeitschriftenartikel Giménez, C.; Climent Terol, Estela; Aznar, E.; Martínez-Mánez, Ramon; Sancenón, F.; Marcos, D.; Amorós, P.; Rurack, Knut Towards chemical communication between gated nanoparticles The design of comparatively simple and modularly configurable artificial systems able to communicate through the exchange of chemical messengers is, to the best of our knowledge, an unexplored field. As a proof-of-concept, we present here a family of nanoparticles that have been designed to communicate with one another in a hierarchical manner. The concept involves the use of capped mesoporous silica supports in which the messenger delivered by a first type of gated nanoparticle is used to open a second type of nanoparticle, which delivers another messenger that opens a third group of gated nanoobjects. We believe that the conceptual idea that nanodevices can be designed to communicate with one another may result in novel applications and will boost further advances towards cooperative systems with complex behavior as a result of the communication between simple abiotic individual components. Weinheim Wiley-VCH Gesellschaft Deutscher Chemiker 2014 Angewandte Chemie / International Edition 53 46 12629 12633 10.1002/anie.201405580 2016-02-20 OPUS4-19846 Monographie Rurack, Knut; Martínez-Mánez, Ramon Biomimetic chemistry of hybrid materials The article discusses representative examples published in the field of functional biomimetic chemistry of hybrid materials between 2004 and mid-2007. First, we focus on the modification of morphological aspects of (bio)organic–inorganic hybrid materials to create sophisticated gating and switching mechanisms. The architecture of the systems is presented and the elements of control by external stimuli that have been established in recent years, such as optical, electrochemical, chemical, thermal, or magnetic means, are described. Various functions ranging from (site-specific) delivery to indication at the nanometric level are reported. Next we develop the idea of utilizing hybrid frameworks for biomimetic signaling inspired by the way nature has created binding pockets and the concept of induced-fit. Such a merging of inorganic scaffolds with supramolecular concepts results in enhanced molecular recognition and signaling. Finally selected recent advances in the field of hybrid biomimetic motors both of linear and rotary types are presented. The contribution shows how novel biomimetic functions can arise from synergisms between specifically designed hybrid materials and the implementation of supramolecular and/or bioorganic concepts. Chichester Wiley 2009 Encyclopedia of inorganic chemistry 1 20 10.1002/0470862106.ia420 2016-02-19 OPUS4-19847 Beitrag zu einem Sammelband Rurack, Knut; Martínez-Mánez, Ramon Robert H. Crabtree, Functional supramolecular hybrid materials The combination of suitable nanoscopic inorganic supports with supramolecular concepts and bioconjugation strategies opens up exciting perspectives for the development of bioinorganic and organic–inorganic hybrid materials with improved functionalities. Many of the examples from the period 2004 to mid-2007 reviewed here bridge the gap between molecules, materials sciences, biochemistry, and nanotechnology. The synergistic use of these approaches has led to the advancement of various functions such as enhanced recognition, amplified signaling, the controlled assembly and disassembly of aggregates and 3-D architectures. Many of the implemented active functions can be carried out in a reversible and directed fashion on purpose by triggering with an external stimulus. These ideas bring tunability to properties of inorganic solids and new perspectives of application to biochemical and supramolecular concepts. Classic inorganic chemistries such as metal or semiconductor nanoparticles, silica or carbon materials, and coordination chemistry are thus elevated to another level of sophistication and contribute significantly to frontier research areas in directed transport and delivery, nanoelectronics and mechanics, chip technology, smart materials, memory devices, and bioanalytics. Chichester Wiley 2009 Encyclopedia of inorganic chemistry 1 23 10.1002/0470862106.ia400 2016-02-19 OPUS4-22908 Zeitschriftenartikel Martínez-Mánez, Ramon; Sancenón, F.; Hecht, Mandy; Biyikal, Mustafa; Rurack, Knut Nanoscopic optical sensors based on functional supramolecular hybrid materials This review highlights how the combination of supramolecular principles and nanoscopic solid structures enables the design of new hybrid sensing ensembles with improved sensitivity and/or selectivity and for the targeting of analytes for which selectivity is hard to achieve by conventional methods. Such ideas are bridging the gap between molecules, materials sciences and nanotechnology. Relevant examples will be detailed, taking into account functional aspects such as (1) enhanced coordination of functionalized solids, (2) enhanced signalling through preorganization, (3) signalling by assembly–disassembly of nanoscopic objects, (4) biomimetic probes utilizing discrimination by polarity and size and (5) distinct switching and gating protocols. These strategies are opening new prospects for sensor research and signalling paradigms at the frontier between nanotechnology, smart materials and supramolecular chemistry. Berlin Springer 2011 Analytical and bioanalytical chemistry 399 1 55 74 10.1007/s00216-010-4198-2 2016-02-19 OPUS4-22868 Vortrag Rurack, Knut Particle-based Hybrid Sensor Materials for Photo- and Fluorometric Detection 2010 Molecular Sensors and Molecular Logic Gates (MSMLG-2010) Molecular Sensors and Molecular Logic Gates (MSMLG-2010) Antalya, Turkey 2010-10-22 2010-10-25 2016-02-19 OPUS4-22869 Vortrag Rurack, Knut Biological and Biomimetic Approaches toward the Detection of Nitro- and Peroxide-based Explosives 2010 International Workshop on Explosives Detection 2010 International Workshop on Explosives Detection 2010 Valencia, Spain 2010-11-25 2016-02-19 OPUS4-21959 Monographie Rurack, Knut; Martínez-Mánez, Ramon Hybrid (nano)materials meet supramolecular chemistry: A brief introduction to basic terms and concepts Hoboken, New Jersey, USA John Wiley & Sons 2010 The supramolecular chemistry of organic - inorganic hybrid materials 978-0-470-37621-8 1 10 2016-02-19 OPUS4-21960 Beitrag zu einem Sammelband Rurack, Knut; Martínez-Mánez, Ramon; Sancenón, F.; Descalzo López, Ana Belén Rurack, Knut; Martínez-Mánez, Ramon Biomimetically inspired signaling Hoboken, New Jersey, USA John Wiley & Sons 2010 The supramolecular chemistry of organic - inorganic hybrid materials 978-0-470-37621-8 549 580 2016-02-19 OPUS4-21961 Beitrag zu einem Sammelband Rurack, Knut; Martínez-Mánez, Ramon Rurack, Knut; Martínez-Mánez, Ramon Supramolecular chemistry meets hybrid (nano)materials: A brief look ahead Hoboken, New Jersey, USA John Wiley & Sons 2010 The supramolecular chemistry of organic - inorganic hybrid materials 978-0-470-37621-8 689 700 2016-02-19 OPUS4-21941 Beitrag zu einem Sammelband Descalzo López, Ana Belén; Zhu, Shengchao; Fischer, Tobias; Rurack, Knut Demchenko, A.P. Optimization of the coupling of target recognition and signal generation Fluorescent reporters that literally "light up" upon binding of a target species are particularly interesting from an analytical point of view. This contribution introduces the main signaling concepts in fluorescent probe research, discusses strategies toward their optimization in terms of signal output, and highlights the wealth of alternative protocols that has been realized in the past two decades to create signaling systems with luminescence amplification features. Springer National Academy of Sciences of Ukraine 2010 Advanced fluorescence reporters in chemistry and biology II: Molecular constructions, polymers and nanoparticles 9 978-3-642-04699-5 1 41 106 10.1007/978-3-642-04701-5_2 2016-02-19 OPUS4-24208 Zeitschriftenartikel Xu, H.-J.; Mack, J.; Descalzo López, Ana Belén; Shen, Z.; Kobayashi, N.; You, X.-Z.; Rurack, Knut meso-Aryl phenanthroporphyrins: Synthesis and spectroscopic properties The successful synthesis of tetraphenyltetraphenanthroporphyrin (TPTPhenP; 5a) in 2006 under modified Rothemund-Lindsey conditions yielded a tetraphenyl porphyrinoid with a B band redshifted to an unprecedented 576 nm. Radially symmetric fused-ring expansion of tetraphenylporphyrin with phenanthrene moieties results in very deep saddling due to steric crowding and very marked redshifts of the Q and B (or Soret) porphyrinoid absorption bands. The extent to which the TPTPhenP structure can be further modified is explored, and the optical properties of TPTPhenPs are analyzed based on a perimeter model approach that makes use of time-dependent DFT calculations and magnetic circular dichroism spectroscopy and also based on a detailed analysis of the fluorescence emission. Attempts to introduce substituents at the ortho and meta positions of the meso-phenyl groups and to insert a central metal proved unsuccessful. The synthesis of a series of TPTPhenPs with strong electron-withdrawing (—CN, —NO2) and -donating (—CH3, —N(CH3)2) substituents at the para positions of the meso-phenyl rings is reported. Marked redshifts of the main spectral bands were consistently observed. The most pronounced spectral changes were observed with —N(CH3)2 groups (5i) due to a marked destabilization of the HOMO, which has large MO coefficients on the meso-carbon atoms. Protonation of 5i at both the ligand core and at the —N(CH3)2 groups resulted in unprecedented Q00 band absorption at wavelengths greater than 1200 nm. Weinheim Wiley-VCH Verl. 2011 Chemistry - A European journal 17 32 8965 8983 10.1002/chem.201002596 2016-02-19 OPUS4-23931 Vortrag Rurack, Knut Molecularly Imprinted Polymer Films as Sensory Materials for the Selective Detection of Carboxylates via Flourescence 2011 European Polymer Congress 2011(EPF) European Polymer Congress 2011(EPF) Granada, Spain 2011-06-26 2011-07-01 2016-02-19 OPUS4-23935 Posterpräsentation Rurack, Knut Implementing Signal Amplification Features with Gated Mesoporous Sensory Hybrids for Methymercury Determination 2011 Hybrid Materials 2011 Hybrid Materials 2011 Strasbourg, France 2011-03-03 2011-03-10 2016-02-19 OPUS4-23936 Vortrag Rurack, Knut Organically functionalized mesopporous silica particles as a versatile platform for Hg2+ determination, sequestration and CH3Hg+ speciation witz simple analytical protocols 2011 ANAKON 2011 ANAKON 2011 Zurich, Switzerland 2011-03-22 2011-03-25 2016-02-19 OPUS4-23987 Zeitschriftenartikel Nöll, G.; Daub, J.; Lutz, M.; Rurack, Knut Synthesis, spectroscopic properties, and electropolymerization of azulene dyads Four azulene dyads have been synthesized and studied by spectroscopic and electrochemical methods. A triarylamine, a boron-dipyrromethene (BDP or BODIPY), a porphyrin, and an isoalloxazine moiety have been linked to an extended π electron system at the 2-position of azulene, leading to the dyads 1-4, respectively. For the synthesis of 1-4, first 2-(4-ethynyl-phenyl)azulene (EPA) was prepared, which was further reacted with the halogenated chromophores by Pd-catalyzed cross-coupling reactions. The dyads 1-4 exhibit strong absorption bands in the visible range, which are dominated by the absorption spectra of the individual subchromophores. Fluorometric studies of 2-4 revealed that after excitation of the subchromophoric unit attached to the parent azulene moiety, quenching mainly through energy transfer to azulene is effective, whereas possible charge-transfer interactions play only a minor role. Potentiodynamic oxidation of the dyads 1-4 leads to the formation of polymer films, which are deposited at the electrode. The polymer film derived from 1 was further characterized by spectroelectrochemistry. During positive doping of poly-1, a strong absorption band appears at 13,200 cm–1, which is typical for triarylamine radical cations. This band is overlapping with a broad absorption band in the low-energy region that might be caused by charge-transfer interactions within the polymer. Washington, DC American Chemical Society 2011 The journal of organic chemistry 76 12 4859 4873 10.1021/jo200080v 2016-02-19 OPUS4-23480 Zeitschriftenartikel Ros-Lis, J.V.; Martínez-Mánez, Ramon; Soto, J.; Villaescusa, L.A.; Rurack, Knut Squaraine 'ships' in the Y zeolite 'bottle': a chromogenic sensing material for the detection of volatile amines and thiols The inclusion of squaraine (SQ) dye I into the supercages of zeolite Y (structure code FAU) with a SiO2/Al2O3 ratio of 30 (Z30) through a two-step ship-in-the-bottle approach is reported, resulting in the squaraine-containing hybrid material Z30-SQ. Attempts to use the same synthetic procedure on sodium and ammonium Y zeolites were unsuccessful, stressing the importance of the presence of Brønsted acid centres in the Z30 zeolite. The reflectance spectra of Z30-SQ show a maximum in the typical squaraine monomer region at 618 nm and a shoulder at 570 nm. Spectral analyses revealed that the major species are SQ dimers and (tightly adsorbed) SQ monomers and SQ aggregates are only formed to a minor degree. The emission spectrum of Z30-SQ shows a single band at 669 nm. The sensory performance of this material was tested in the presence of volatile propylamine and propylthiol and other volatile organic compounds (acetone, ethanol, dichloromethane, hexane, acetonitrile, ethyl acetate, ethyl ether and acetic acid). The blue Z30-SQ material reacts with the thiol and amine derivatives, resulting in the bleaching of the solid and disappearance of the absorption band in the visible region, but does not undergo spectroscopic changes in the presence of other volatile organic compounds (VOCs). Whereas the reaction with propylamine is irreversible, a partial reversibility was found in the presence of the thiol. Theoretical investigations of the reactivity of I with several VOC molecules at the semi-empirical level reproduced well the experimentally observed reactivity. Cambridge Royal Society of Chemistry 2011 Journal of materials chemistry 21 13 5004 5010 10.1039/c0jm03780j 2016-02-19 OPUS4-23481 Zeitschriftenartikel Rurack, Knut; Spieles, Monika Fluorescence quantum yields of a series of red and near-infrared dyes emitting at 600-1000 nm The determination of the fluorescence quantum yields (QY, Φf) of a series of fluorescent dyes that span the absorption/excitation and emission ranges of 520-900 and 600-1000 nm is reported. The dyes encompass commercially available rhodamine 101 (Rh-101, Φf = 0.913), cresyl violet (0.578), oxazine 170 (0.579), oxazine 1 (0.141), cryptocyanine (0.012), HITCI (0.283), IR-125 (0.132), IR-140 (0.167), and four noncommercial cyanine dyes with specific spectroscopic features, all of them in dilute ethanol solution. The QYs have been measured relative to the National Institute of Standards and Technology's standard reference material (SRM) 936a (quinine sulfate, QS) on a traceably characterized fluorometer, employing a chain of transfer standard dyes that include coumarin 102 (Φf = 0.764), coumarin 153 (0.544), and DCM (0.435) as links between QS and Rh-101. The QY of Rh-101 has also been verified in direct measurements against QS using two approaches that rely only on instrument correction. In addition, the effects of temperature and the presence of oxygen on the fluorescence quantum yield of Rh-101 have been assessed. Washington, DC American Chemical Society 2011 Analytical chemistry 83 4 1232 1242 10.1021/ac101329h 2016-02-19 OPUS4-23633 Zeitschriftenartikel Zhu, Shengchao; Fischer, Tobias; Wan, Wei; Descalzo López, Ana Belén; Rurack, Knut Luminescence amplification strategies integrated with microparticle and nanoparticle platforms The amplification of luminescence signals is often the key to sensitive and powerful detection protocols. Besides optimized fluorescent probes and labels, functionalized nano- and microparticles have received strongly increasing attention in this context during the past decade. This contribution introduces the main signalling concepts for particle-based amplification strategies and stresses, especially the important role that metal and semiconductor nanoparticles play in this field. Besides resonance energy transfer, metal-enhanced emission and the catalytic generation of luminescence, the impact of multi-chromophoric objects such as dye nanocrystals, dendrimers, conjugated polymers or mesoporous hybrid materials is assessed. The representative examples discussed cover a broad range of analytes from metal ions and small organic molecules to oligonucleotides and enzyme activity. Berlin ; Heidelberg [u.a.] Springer 2011 Topics in current chemistry 300 51 91 10.1007/128_2010_99 2016-02-19 OPUS4-18545 Posterpräsentation Rurack, Knut Vom Indikatormolekül zum Sensorpartikel - unterwegs zu leistungsfähigen miniaturisierten Analyseplattformen 2008 IGAS Jahreskolloquium IGAS Jahreskolloquium Berlin, Germany 2008-11-10 2016-02-19 OPUS4-18547 Posterpräsentation Rurack, Knut Functional red/NIR dyes and hybrid sensor materials 2008 Working Group Meeting, COST D-31, Working Group 001204 "New Materials for Anion Sensing", School of Chemistry Working Group Meeting, COST D-31, Working Group 001204 "New Materials for Anion Sensing", School of Chemistry Birmingham, England 2008-01-25 2016-02-19 OPUS4-19146 Zeitschriftenartikel Descalzo López, Ana Belén; Rurack, Knut On the signalling pathways and Cu(II)-mediated anion indication of N-meso-substituted heptamethine cyanine dyes Three mid-chain rigidified heptamethine cyanine dyes substituted with dimethylamino or cyclam groups at the meso position of the polymethine chain have been prepared and studied both experimentally and theoretically with respect to their spectroscopic response toward protons and various metal ions. Despite a potentially rich conformational ground-state chemistry, the spectroscopic studies revealed that the behaviour of the dyes is in agreement with Kuhn's classic polymethine dye theory. Coordination of metal ions and protonation of the alkyl amino groups in the cyclam moiety accordingly lead to moderate bathochromic shifts in absorption and reduced Stokes shifts. In contrast, protonation of the dimethylamino-substituted derivatives occurs at the polymethine chain, transforming the heptamethine into a trimethine-type chromophore with concomitant gigantic spectral blueshifts. In the presence of CuII in buffered aqueous solution, the cyclam-substituted dye selectively forms near-infrared absorbing aggregates. The latter allow the determination of citrate under realistic conditions by changes in absorption at wavelengths greater than 800 nm, which results from a disruption of the aggregates when citrate binds to CuII. The copper ions thus act as mediators in a signalling reaction that constitutes a colourimetric displacement assay. Weinheim Wiley-VCH Verl. 2009 Chemistry - A European journal 15 13 3173 3185 10.1002/chem.200802087 2016-02-19 OPUS4-19133 Vortrag Rurack, Knut Biomimetically Inspired Sensing of Ionic and Neutral Species with Organically Modified Mesoporous Silica Materials 2009 First International Conference on Multifunctional, Hybrid and Nanomaterials First International Conference on Multifunctional, Hybrid and Nanomaterials Tours, France 2009-03-15 2009-03-19 2016-02-19 OPUS4-20286 Zeitschriftenartikel Kammer, S.; Kelling, A.; Baier, H.; Mickler, W.; Dosche, C.; Rurack, Knut; Kapp, A.; Lisdat, F.; Holdt, H.-J. 2,11-dialkylated 1,12-diazaperylene copper(I) complexes: First supramolecular column assemblies by Pi-Pi stacking between homoleptic tetrahedral metal complexes, exhibiting low-energy MLCT transitions Weinheim Wiley-VCH Verl. 2009 European journal of inorganic chemistry 2009 31 4648 4659 10.1002/ejic.200900695 2016-02-19 OPUS4-20308 Zeitschriftenartikel Climent Terol, Estela; Marcos, D.; Martínez-Mánez, Ramon; Sancenón, F.; Soto, J.; Rurack, Knut; Amorós, P. The determination of methylmercury in real samples using organically capped mesoporous inorganic materials capable of signal amplification Weinheim Wiley-VCH Gesellschaft Deutscher Chemiker 2009 Angewandte Chemie / International Edition 48 45 8519 8522 10.1002/anie.200904243 2016-02-19 OPUS4-20318 Beitrag zu einem Sammelband Martínez-Mánez, Ramon; Sancenón, F.; Descalzo López, Ana Belén; Rurack, Knut Abd-El Aziz, Alaa S.; Carraher, Charles E.; Pittman, Charles U.; Zeldin, Martel Supramolecular hybrid materials - integrating functionality with sensing Hoboken, New Jersey, USA John Wiley & Sons 2009 Macromolecules containing metal and metal-like elements - Supramolecular and self-assembled metal-containing materials 9 978-0-470-25144-7 369 405 2016-02-19 OPUS4-38402 Beitrag zu einem Tagungsband Wander, Lukas; Paul, Andrea; Rurack, Knut; Biyikal, Mustafa; Juritsch, Elevtheria; Bernstein, Thomas; Bartholmai, Matthias; Noske, Reinhard Kompaktsensor zur Online-Überwachung von Nitroaromaten Nitroaromaten und insbesondere Trinitrotoluol (TNT) sind weit verbreitete Spreng- und Umweltschadstoffe. Die größte Herausforderung bei der Detektion von TNT in der Gasphase ist der geringe Dampfdruck. Derzeit werden vielerorts günstige, schnelle, handliche und einfach zu bedienende Alternativen zur klassischen TNT-Analytik entwickelt. Aktuell existieren keine einheitlichen Richtlinien für Sprengstoffsensoren. Hier wird die Entwicklung eines Messplatzes zur Validierung von Sprengstoffsensoren sowie die Erprobung eines kompakten Mustersensors vorgestellt. 2016 Tagungsband – 12. Kolloquium Prozessanalytik 12. Kolloquium Prozessanalytik Berlin, Germany 28.11.2016 30.12.2016 P11, 61 62 2016-11-22 OPUS4-35098 Zeitschriftenartikel Opel, J.; Hecht, Mandy; Rurack, Knut; Eiblmeier, J.; Kunz, W.; Cölfen, H.; Kellermeier, M. Probing local pH-based precipitation processes in self-assembled silica-carbonate hybrid materials Crystallisation of barium carbonate in the presence of silica can lead to the spontaneous assembly of highly complex superstructures, consisting of uniform and largely co-oriented BaCO3 nanocrystals that are interspersed by a matrix of amorphous silica. The formation of these biomimetic architectures (so-called silica biomorphs) is thought to be driven by a dynamic interplay between the components, in which subtle changes of conditions trigger ordered mineralisation at the nanoscale. In particular, it has been proposed that local pH gradients at growing fronts play a crucial role in the process of morphogenesis. In the present work, we have used a special pH-sensitive fluorescent dye to directly trace these presumed local fluctuations by means of confocal laser scanning microscopy. Our data demonstrate the existence of an active region near the growth front, where the pH is locally decreased with respect to the alkaline bulk solution on a length scale of few microns. This observation provides fundamental and, for the first time, direct experimental support for the current picture of the mechanism underlying the formation of these peculiar materials. On the other hand, the absence of any temporal oscillations in the local pH – another key feature of the envisaged mechanism – challenges the notion of autocatalytic phenomena in such systems and raises new questions about the actual role of silica as an additive in the crystallisation process. Cambridge RSC Publ. 2015 Nanoscale 7 41 17434 17440 10.1039/c5nr05399d 2016-02-20 OPUS4-35092 Zeitschriftenartikel Bierstedt, Andreas; Panne, Ulrich; Rurack, Knut; Riedel, Jens Characterization of two modes in a dielectric barrier discharge probe by optical emission spectroscopy and time-of-flight-mass spectrometry Among the large number of new ambient ionization schemes in the last few years, dielectric barrier discharge (DBD) has witnessed special attention. In this contribution a versatile dual mode DBD is introduced and characterized by means of optical emission spectroscopy and time-of-flight mass spectrometry. A direct comparison of the individual results from spectroscopy, spectrometry and transient current/voltage consumption gives evidence for the existence of two individual operational mechanisms. The first is driven by rapid transient changes in the potential difference between the two electrodes over time (usually denoted as the homogeneous mode), while the second is caused at high static potential differences (leading to filamentary discharges). The transient versus steady-state characteristics of the individual discharge origin suggest the driving force for the current flow to be inductive and capacitive, respectively. In most cases of dielectric barrier plasmas both discharge types coexist as competitive ion formation channels, however, detailed plasma characteristics of DBDs operated under different conditions allow for a clear distinction of the individual contributions. In this way, two characteristic product channels for the ionization of ambient water could be observed resulting in the generation of either preferentially protonated water clusters or ammonium water clusters. Careful tuning of the operation parameters of the discharge device allows an operation predominated by either of the two modes. As a consequence, facile switching into the desired operational mode results in either protonated molecules or ammoniated molecules of the analyte. Plasma characteristics for both moieties were evaluated and cross-correlated on the basis of several factors including: the production of reagent ions, the individual appearance of current/voltage profiles, UV/Vis spectroscopy, voltage and flux dependence and the individual response to test compounds. Although the filamentary mode has been already discussed in the literature to induce fragmentation processes, no experimental evidence for analyte dissociation could be found in the case of the test compounds used London Royal Society of Chemistry 2015 Journal of analytical atomic spectrometry 30 12 2496 2506 10.1039/C5JA00332F 2016-02-20 OPUS4-33635 Posterpräsentation Rurack, Knut Fluorescent mesoporous silicia materials discriminating Ag(l) and Hg (II) 2015 25th Congress of the Analytical Chemistry Division of the Italian Chemical Society 25th Congress of the Analytical Chemistry Division of the Italian Chemical Society Trieste, Italien 2015-09-13 2015-09-17 2016-02-20 OPUS4-38794 Vortrag Rurack, Knut The Integration of Fluorescent Probes with Sensing Matrices Integrating fluorescent probes with sensing matrices presents a major challenge because usually, when confined in a rather rigid matrix, fluorophores tend to behave completely different than for instance in the molecular state in solution. The lecture reviews the major strategies that have been devised recently to circumvent such issues with special focus on the works carried out in this field by BAM's Chemical and Optical Sensing Division. Moreover, it will be shown that by using certain strategies not only can the response behavior be retained but synergistic effects can even endow the hybrid with a much better performance than the probe molecule alone. 2016 GDCh-Kolloquium Braunschweig, Germany 14.11.2016 14.11.2016 2016-12-22 OPUS4-38795 Vortrag Rurack, Knut Improving the Sensing Performance of Macrocycle-containing Fluorescent Probes by Integration into Mesoporous Silica Macrocycle-containing fluorescent probes continue to be one of the most popular classes of indicator molecules for the sensitive optical detection of ionic inorganic analytes, in particular metal ions, since the first integration of crown ether building blocks into chromophoric π systems more than 30 years ago. However, whereas a large multitude of such probes have been described for operation in organic or mixed aqueous environments, the step to realistic analytical media such as water samples, aqueous food extracts or body fluids is still scarce. On one hand, this is due to considerably low complex stability constants for instance for alkali and alkaline-earth metal ions. On the other hand, many classes of organic dyes that show favourable spectroscopic properties and ion-induced responses in organic solvents are not soluble in neat aqueous media and/or exhibit only significantly quenched fluorescence, even if transition metal ions are binding strongly to the receptor unit. A way to circumvent such problems in a rather simple manner is the steric incorporation of fluorescent probes into mesoporous silica nanomaterials. The local polarity in such pores, whether nascent or modified appropriately with functional silanes, resembles much more a quasi-organic environment while at the same time allowing for free diffusion of water and its cargo. Two examples of powerful hybrid signalling systems will be presented, utilizing charge transfer-type indicator molecules that show inferior sensing properties in their molecular state. One example discusses mercury(II) determination over an extended concentration range and the other discusses silver(I) and mercury(II) discrimination simply on the basis of photophysical effects retained in the hybrid materials. 2016 The 1st Nanjing/Dijon Symposium on Functional Macrocyclic Molecules Nanjing, People's Republic of China 09.07.2016 10.07.2016 2016-12-22 OPUS4-38796 Vortrag Rurack, Knut Bright Long-Wavelength Pyrrolic Dyes - Prospects for Applications in Fluorescence Sensing Since more than 20 years, optical spectroscopic techniques, in particular fluorescence-based methods, are on the rise in many different areas of chemical and biochemical analysis, with no end being in sight.1,2 Advances in miniaturization and remote applications on one hand and ground-breaking developments in microscopy and laser-based high-throughput instrumentation on the other hand have fuelled these developments substantially.3,4 At the core of utmost of these applications however is not only the instrument, but a small entity that is able to absorb and emit photons and thus to report on the actual (bio)chemistry that is going on in a particular sample of interest.5,6 Besides intense research on various types of luminescent particles (e.g., quantum dots and carbon dots) and proteins, dye chemistry has thus seen its revival and the number of publications dealing with the design, synthesis and application of new fluorescent dyes as probes, stains, labels or indicators is still continuing to grow. Among the various classes of dyes available as bright fluorophores for a wavelength range that is compatible with many (bio)analytical applications and the respective instrumentation, in particular pyrrolic dyes that do not belong to the classical porphyrins or phthalocyanines have received strong attention recently. Starting perhaps with the revival of the traditional boron-dipyrromethene laser dye ca. 15 years ago,7 these so-called BODIPYs have developed into a colourful spectrum of different derivatives.8 However, the interest in expanding the range of pyrrole-containing π-systems beyond BODIPYs has also constantly increased and has brought about several other pyrrole-based ring systems such as diketopyrrolopyrroles9 or dipyrrolonaphthyridinediones which possess a favourable brightness and other interesting properties. The present contribution will give a critical overview of the field, pinpointing advantages and prospects as well as discussing potential aspects of improvement with an emphasis on the chemical sensing and the longer wavelength range. 2016 Ninth International Conference on Porphyrins and Phthalocyanines Nanjing, People's Republic of China 03.07.2016 08.07.2016 2016-12-22 OPUS4-38798 Buchkapitel Gawlitza, Kornelia; Wan, Wei; Wagner, Sabine; Rurack, Knut Tiwari, Ashutosh; Uzun, Lokman Fluorescent Molecularly Imprinted Polymers An ideal sensor system is a combination of a selective receptor, an effective transducer, and a sensitive detector. To utilize molecularly imprinted polymers (MIPs) as responsive recognition phases in sensors, the employment of fluorescent molecules or nanoparticles (NPs) that show prominent changes in their spectroscopic properties after binding of the target molecule in the MIP's cavity is particularly attractive. Such fluorescent MIPs (fMIPs) act through target-induced quenching, enhancement, or spectral shifts of the fluorescence. This contribution introduces different strategies of incorporation of fluorescent dyes, probes, and NPs into fMIPs. In addition, various sensing mechanisms are reviewed, and depending on the application of the sensor, the different deployable formats, their advantages, drawbacks, and impact will be presented and discussed. 1 Beverly, MA Scrivener Publishing, WILEY 2017 Advanced Molecularly Imprinting Materials 978-1-119-33629-7 89 128 2016-12-22 OPUS4-45398 Zeitschriftenartikel Lozano-Torres, B.; Marcos, M. Dolores; Pardo, T.; Sancenón, F.; Martínez-Mánez, Ramon; Rurack, Knut Anilinopyridine-metal complexes for the selective chromogenic sensing of cyanide anion Probe 1, which contains an anilinopyridine chromophore and an azaoxa macrocyclic subunit, presented an absorption band centered at 340 nm in acetonitrile. Addition of Fe(III), Cr(III) and Hg(II) induced the growth of a new absorption band at 430 nm (with color change from colorless to yellow), whereas in the presence of Cu(II), Zn(II) and Pb(II), less marked changes were observed. The color changes observed upon addition of Fe(III), Cr(III) and Hg(II) were ascribed to the formation of 1:1 stoichiometry complexes with probe 1. Coordination of Fe(III), Cr(III) and Hg(II) with the pyridine fragment of 1 induced an enhancement of the charge transfer character accompanied with a marked bathochromic shift that was reflected in a color change from colorless to yellow. The strength of the interaction between probe 1 and Fe(III) cation was modulated upon interaction with anions. Of all the anions tested, only cyanide was able to induce the bleaching of the yellow 1·Fe(III) complex solution. This bleaching was ascribed to the formation of 1·Fe(III)-CN complex that restored, to some extent, the optical features of the free probe allowing the chromogenic sensing of cyanide. Besides, 1·Fe(III) complex was used to detect cyanide in acetonitrile-water 90:10 v/v mixtures with good recoveries. London Taylor & Francis Group 2018 Journal of Coordination Chemistry 71 6 786 796 10.1080/00958972.2018.1434719 2018-07-09 OPUS4-45399 Zeitschriftenartikel Wagner, Sabine; Zapata, Carlos; Wan, Wei; Gawlitza, Kornelia; Weber, M.; Rurack, Knut Role of Counterions in Molecularly Imprinted Polymers for Anionic Species Small-molecule oxoanions are often imprinted noncovalently as carboxylates into molecularly imprinted polymers (MIPs), requiring the use of an organic counterion. Popular species are either pentamethylpiperidine (PMP) as a protonatable cation or tetraalkylammonium (TXA) ions as permanent cations. The present work explores the influence of the TXA as a function of their alkyl chain length, from methyl to octyl, using UV/vis absorption, fluorescence titrations, and HPLC as well as MD simulations. Protected phenylalanines (Z-L/D-Phe) served as templates/analytes. While the influence of the counterion on the complex stability constants and anion-induced spectral changes shows a monotonous trend with increasing alkyl chain length at the prepolymerization stage, the cross-imprinting/rebinding studies showed a unique pattern that suggested the presence of adaptive cavities in the MIP matrix, related to the concept of induced fit of enzyme−substrate interaction. Larger cavities formed in the presence of larger counterions can take up pairs of Z-X-Phe and smaller TXA, eventually escaping spectroscopic detection. Correlation of the experimental data with the MD simulations revealed that counterion mobility, the relative distances between the three partners, and the hydrogen bond lifetimes are more decisive for the response features observed than actual distances between interacting atoms in a complex or the orientation of binding moieties. TBA has been found to yield the highest imprinting factor, also showing a unique dual behavior regarding the interaction with template and fluorescent monomer. Finally, interesting differences between both enantiomers have been observed in both theory and experiment, suggesting true control of enantioselectivity. The contribution concludes with suggestions for translating the findings into actual MIP development. Washington, D.C. American Chemical Society 2018 Langmuir 34 23 6963 6975 10.1021/acs.langmuir.8b00500 2018-07-09 OPUS4-44478 Zeitschriftenartikel Bell, Jérémy; Gawlitza, Kornelia; Rurack, Knut Die 3D-Mikrofluidik mit molekular geprägten Polymerpartikeln eröffnet neue Möglichkeiten der selektiven Pestizid-Bestimmung in Wasser 2,4-D ist ein in der Landwirtschaft weitverbreitetes Pflanzenschutzmittel, das Grundwasser kontaminiert, sich innerhalb der Nahrungskette anreichert und Umwelt- und Gesundheitsprobleme verursachen kann. Hier stellen die Autoren ein mikrofluidisches Nachweissystem für die Echtzeitdetektion von 2,4-D in Grund- oder Oberflächenwasser vor. Es basiert auf der Kombination 2,4-D-selektiver, fluoreszierender, molekular geprägter Polymer-(MIP-)Mikropartikel mit einem 3D-mikrofluidischen Extraktions- und Detektionssystem. Messungen vor Ort sollen damit künftig möglich sein. WEKA Business Medien GmbH 2018 Labo - Mikrofluidische Systeme 3 10 13 urn:nbn:de:kobv:b43-444781 http://www.gesetze-im-internet.de/urhg/index.html 2018-03-19 OPUS4-49130 Vortrag Bell, Jérémy; Tillo, Adam; Chauhan, Vraj P.; Bartelmeß, Jürgen; Rurack, Knut Microfluidic analytical tool coupling a fluorescent molecular probe and a micro-hydrocyclone for the detection of water chlorination level Chlorination of pool water and wastewater, in food and pharmaceutical production, as well as in pesticide and paper manufacturing is a routinely used technique. However, the amount of chlorine in water must be strictly adjusted, to ensure enough concentration to kill pathogenic bacteria and viruses, while preventing too high concentrations inducing negative effects on human health. As an indicator, a molecular fluorescent probe based on a BODIPY structure was designed. This indicator exhibits a sensitive and selective fluorescence response upon increasing concentrations of hypochlorite in aqueous solvent mixtures. Real-time analyses became possible after the integration of this fluorescent indicator into newly designed 2D & 3D microfluidic chips incorporating a passive sinusoidal mixer and a micro-hydrocyclone, respectively. A comparison of the two microfluidic systems, including their ability to prevent accumulation or circulation of microbubbles, has shown excellent fluidic behaviour for the micro-hydrocyclone device. This system was distinctly more robust against gas bubbles, showed a higher signal gain and allowed to halve the limit of detection to 0.02 mg L-1. The use of the 3D system to quantify the chlorine content of pool water samples for sensitive and quantitative chlorine monitoring has been demonstrated. 2019 Konferenz Ioannina, Greece 22.09.2019 25.09.2019 2019-09-27 OPUS4-50948 Zeitschriftenartikel Li, Q.; Shinde, S.; Grasso, G.; Caroli, A.; Abouhany, R.; Lanzillotta, M.; Pan, G.; Wan, Wei; Rurack, Knut; Sellergren, B. Selective detection of phospholipids using molecularly imprinted fluorescent sensory core-shell particles Sphingosine-1-phosphate (S1P) is a bioactive sphingo-lipid with a broad range of activities coupled to its role in G-protein coupled receptor signalling. Monitoring of both intra and extra cellular levels of this lipid is challenging due to its low abundance and lack of robust affinity assays or sensors. We here report on fluorescent sensory core-shell molecularly imprinted polymer (MIP) particles responsive to near physiologically relevant levels of S1P and the S1P receptor modulator fingolimod phosphate (FP) in spiked human serum samples. Imprinting was achieved using the tetrabutylammonium (TBA) salt of FP or phosphatidic acid (DPPA·Na) as templates in combination with a polymerizable nitrobenzoxadiazole (NBD)-urea monomer with the dual role of capturing the phospho-anion and signalling its presence. The monomers were grafted from ca 300 nm RAFT-modified silica core particles using ethyleneglycol dimethacrylate (EGDMA) as crosslinker resulting in 10-20 nm thick shells displaying selective fluorescence response to the targeted lipids S1P and DPPA in aqueous buffered media. Potential use of the sensory particles for monitoring S1P in serum was demonstrated on spiked serum samples, proving a linear range of 18-60 μM and a detection limit of 5.6 μM, a value in the same range as the plasma concentration of the biomarker. London Nature Research 2020 Scientific Reports 10 1 9924 urn:nbn:de:kobv:b43-509485 10.1038/s41598-020-66802-3 https://creativecommons.org/licenses/by/4.0/deed.de 2020-06-29 OPUS4-50866 Zeitschriftenartikel Krahl, T.; Beer, F.; Relling, A.; Gawlitza, Kornelia; Rurack, Knut; Kemnitz, E. Toward Luminescent Composites by Phase Transfer of SrF2 :Eu3+ Nanoparticles Capped with Hydrophobic Antenna Ligands Transparent dispersions of hydrophobic SrF2 :Eu3+ nanoparticles in cyclohexane with up to 20% europium were obtained by fluorolytic sol-gel synthesis followed by Phase transfer into cyclohexane through capping with sodium dodecylbenzenesulfonate (SDBS). The particles were characterized by TEM, XRD and DLS as spherical objects with a diameter between 6 and 11 nm in dry state. 1H-13CP MAS NMR experiments revealed the binding of the anionic sulfonate head group to the particle surface. The particles show bright red luminescence upon excitation of the aromatic capping agents, acting as antennas for an Energy transfer from the benzenesulfonate unit to the Eu3+ centers in the particles. This synthesis method overcomes the current obstacle of the fluorolytic sol-gel synthesis that transparent dispersions can be obtained directly only in hydrophilic solvents. To demonstrate the potential of such hydrophobized alkaline-earth fluoride particles, transparent luminescent organic-inorganic composites with 10% SrF2 :Eu3+ embedded into polyTEGDMA, polyBMA, poly-BDDMA and polyD3MA, respectively, were prepared, endowing the polymers with the luminescence features of the nanoparticles. Wiley 2020 ChemNanoMat 1 11 urn:nbn:de:kobv:b43-508668 10.1002/cnma.202000058 https://creativecommons.org/licenses/by-nc/4.0/deed.de 2020-06-11 OPUS4-50867 Beitrag zu einem Tagungsband Gawlitza, Kornelia; Johann, Sergej; Mansurova, M.; Kohlhoff, Harald; Tiebe, Carlo; Bell, Jérémy; Bartholmai, Matthias; Rurack, Knut Semi-automatic Measurement Device for Long-Term Monitoring of Ammonia in Gas Phase The present paper describes the development of a sensor material that changes its fluorescence in the presence of gaseous ammonia in a relevant concentration range. The implementation into a semi-automatic gas measurement device enables low-cost, precise, simple and fast monitoring of low con-centrations of harmful gases, like ammonia, and hence can help to improve the climate monitoring in livestock housing, barns or stables. 2020 SMSI 2020 Proceedings SMSI 2020 Meeting was canceled 133 134 10.5162/SMSI2020/B5.4 2020-06-11 OPUS4-51444 Posterpräsentation Bell, Jérémy; Biyikal, Mustafa; Rurack, Knut Embedded sensor based on tandem smartphone-microfluidic device for the detection of TNT in surface and sea waters The globe's seas were used as dumping ground after the world wars and those millions of ammunition, most of all containing 2,4,6-trinitrotoluene (TNT), represent a pressing danger for fishermen, dredging operations, submarine cable installations and tourism. We developed an extremely selective indication method for TNT based on a specific reaction that produces a highly fluorescent compound. The indication system was integrated into a microfluidic PDMS chip for the solid-liquid extraction of TNT from water samples, offering environmental monitoring possibilities. Combining the advantages of a light-up indicator, microfluidics and a smartphone as detector, the embedded sensor allows for the remote and rapid detection of TNT down to ng in surface and sea waters. 2020 µTAS 2020 Online meeting 05.10.2020 09.10.2020 2020-10-21 OPUS4-35487 Zeitschriftenartikel Bolz, Axel; Panne, Ulrich; Rurack, Knut; Buurman, Merwe Glass fibre paper-based test strips for sensitive SERS sensing We present paper-based test strips for chemical sensing with surface enhanced Raman scattering as detection method. The test strips are prepared on glass fibre paper with silver nanoparticles and a spray method with an airbrush spray setup as a low cost fabrication approach. The properties of the test strips are investigated with three classical Raman analytes rhodamine 6G, 4-aminothiophenol and adenine and optimized for a good reproducibility of the intensity measurements. All test analytes can be identified at low concentrations. For adenine, a concentration series from 10⁻⁴ M to 10⁻⁸ M is measured and the calibration data can be fitted and evaluated with a Langmuir isotherm model. The optimized test strips are applied for the identification of two antibiotics enoxacin and enrofloxacin. The Royal Society of Chemistry 2016 Analytical Methods 8 6 1313 1318 urn:nbn:de:kobv:b43-354878 10.1039/C5AY03096J http://creativecommons.org/licenses/by-nc/3.0/de/deed.de 2016-03-16 OPUS4-35227 Zeitschriftenartikel Shinde, S.; El-Schich, Z.; Malakpour, A.; Wan, Wei; Dizeyi, N.; Mohammadi, R.; Rurack, Knut; Gjörloff Wingren, A.; Sellergren, B. Sialic acid-imprinted fluorescent core-shell particles for selective labeling of cell surface glycans The expression of cell surface glycans terminating with sialic acid (SA) residues has been found to correlate with various disease states there among cancer. We here report a novel strategy for specific fluorescence labeling of such motifs. This is based on sialic acid-imprinted core-shell nanoparticles equipped with nitrobenzoxadiazole (NBD) fluorescent reporter groups allowing environmentally sensitive fluorescence detection at convenient excitation and emission wavelengths. Imprinting was achieved exploiting a hybrid approach combining reversible boronate ester formation between p-vinylphenylboronic acid and SA, the introduction of cationic amine functionalities, and the use of an NBD-appended urea-monomer as a binary hydrogen-bond donor targeting the SA carboxylic acid and OH functionalities. The monomers were grafted from 200 nm RAFT-modified silica core particles using ethylene glycol dimethacrylate (EGDMA) as cross-linker resulting in a shell thickness of ca. 10 nm. The particles displayed strong affinity for SA in methanol/water mixtures (K = 6.6 × 105 M-1 in 2% water, 5.9 × 103 M-1 in 98% water, Bmax ≈ 10 µmol g-1), whereas binding of the competitor glucuronic acid (GA) and other monosaccharides was considerably weaker (K (GA) = 1.8 × 103 M-1 in 98% water). In cell imaging experiments, the particles selectively stained different cell lines in correlation with the SA expression level. This was further verified by enzymatic cleavage of SA and by staining using a FITC labeled SA selective lectin. Washington, DC, USA American Chemical Society 2015 Journal of the American Chemical Society : JACS 137 43 13908 13912 10.1021/jacs.5b08482 2016-02-20 OPUS4-35827 Zeitschriftenartikel Hesse, Almut; Biyikal, Mustafa; Rurack, Knut; Weller, Michael G. Development of highly sensitive and selective antibodies for the detection of the explosive pentaerythritol tetranitrate (PETN) by bioisosteric replacement An improved antibody against the explosive pentaerythritol tetranitrate (PETN) was developed. The immunogen was designed by the concept of bioisosteric replacement, which led to an excellent polyclonal antibody with extreme selectivity and immunoassays of very good sensitivity. Compounds such as nitroglycerine, 2,4,6-trinitrotoluene, 1,3,5-trinitrobenzene, hexogen (RDX), 2,4,6-trinitroaniline, 1,3-dinitrobenzene, octogen (HMX), triacetone triperoxide (TATP), ammonium nitrate, 2,4,6-trinitrophenol and nitrobenzene were tested for potential cross-reactivity. The detection limit of a competitive enzyme-linked immunosorbent assay (ELISA) was determined to be around 0.5 µg/L. The dynamic range of the assay was found to be between 1 µg/L and 1000 µg/L, covering a concentration range of three decades. This work shows the successful application of the bioisosteric concept in immunochemistry by exchange of a nitroester to a carbonate diester. The antiserum might be used for the development of quick tests, biosensors, microtitration plate immunoassays, microarrays and other analytical methods for the highly sensitive detection of PETN, an explosive frequently used by terrorists, exploiting the extreme difficulty of its detection. New York, USA John Wiley & Sons, Ltd. 2016 Journal of Molecular Recognition 29 88 94 10.1002/jmr.2511 2016-04-27 OPUS4-35830 Zeitschriftenartikel Wan, Wei; Wagner, Sabine; Rurack, Knut Fluorescent monomers: "bricks" that make a molecularly imprinted polymer "bright" Molecularly imprinted polymers (MIPs) are potent and established recognition phases in separation and enrichment applications. Because of their robustness, versatility and format adaptability, they also constitute very promising sensing phases, especially when the active sensing element is directly integrated into the MIP. Fluorescent MIPs incorporating fluorescent monomers are perhaps the best developed and most successful approach here. This article reviews the state of the art in this field, discussing the pros and cons of the use of fluorescent dye and probe derivatives as such monomers, the different molecular interaction forces for template complexation, signalling modes and a variety of related approaches that have been realized over the years, including Förster resonance energy transfer processes, covalent imprinting, postmodification attachment of fluorescent units and conjugated polymers as MIPs; other measurement schemes and sensing chemistries that use MIPs and fluorescence interrogation to solve analytical problems (fluorescent competitive assays, fluorescent analytes, etc.) are not covered here. Throughout the article, photophysical processes are discussed to facilitate understanding of the effects that can occur when one is planning for a fluorescence response to happen in a constrained polymer matrix. The article concludes with a concise assessment of the suitability of the different formats for sensor realization. Berlin Springer 2016 Analytical and Bioanalytical Chemistry 408 7 1753 1771 10.1007/s00216-015-9174-4 2016-04-28 OPUS4-35831 Zeitschriftenartikel Bell, Jérémy; Climent Terol, Estela; Hecht, Mandy; Buurman, Merwe; Rurack, Knut Combining a droplet-based microfluidic tubing system with gated indicator releasing nanoparticles for mercury trace detection A droplet-based microfluidic sensor was developed for the detection of Hg2+ traces in water. The approach uses gated mesoporous nanoparticles loaded with a fluorescent BODIPY dye. The squaraine-based gating mechanism is highly selective for Hg2+ and the indicator release mechanism ensures sensitive detection. The microfluidic system is modular and was assembled from simple PTFE/PFA tubes, while detection was realized with standard optomechanic, optic, and electronic parts. The sensor shows a stable response without memory effects and allows the detection of Hg2+ in water down to 20 ppt. Washington, DC American Chemical Society American Chemical Society 2016 ACS Sensors 1 4 334 338 10.1021/acssensors.5b00303 2016-04-28 OPUS4-35832 Zeitschriftenartikel Fischer, Tobias; Dietrich, Paul; Unger, Wolfgang; Rurack, Knut Multimode surface functional group determination: combining steady-state and time-resolved fluorescence with X‑ray photoelectron spectroscopy and absorption measurements for absolute quantification The quantitative determination of surface functional groups is approached in a straightforward laboratory-based method with high reliability. The application of a multimode BODIPY-type fluorescence, photometry, and X-ray photoelectron spectroscopy (XPS) label allows estimation of the labeling ratio, i.e., the ratio of functional groups carrying a label after reaction, from the elemental ratios of nitrogen and fluorine. The amount of label on the surface is quantified with UV/vis spectrophotometry based on the molar absorption coefficient as molecular property. The investigated surfaces with varying density are prepared by codeposition of 3-(aminopropyl) triethoxysilane (APTES) and cyanoethyltriethoxysilane (CETES) from vapor. These surfaces show high functional group densities that result in significant fluorescence quenching of surface-bound labels. Since alternative quantification of the label on the surface is available through XPS and photometry, a novel method to quantitatively account for fluorescence quenching based on fluorescence lifetime (τ) measurements is shown. Due to the complex distribution of τ on high-density surfaces, the stretched exponential (or Kohlrausch) function is required to determine representative mean lifetimes. The approach is extended to a commercial Rhodamine B isothiocyanate (RITC) label, clearly revealing the problems that arise from such charged labels used in conjunction with silane surfaces. Washington, DC American Chemical Society American Chemical Society 2016 Analytical Chemistry 88 2 1210 1217 DOI: 10.1021/acs.analchem.5b03468 2016-04-27 OPUS4-35833 Zeitschriftenartikel Sarma, Dominik; Gawlitza, Kornelia; Rurack, Knut Polystyrene Core−Silica Shell Particles with Defined Nanoarchitectures as a Versatile Platform for Suspension Array Technology The need for rapid and high-throughput screening in analytical laboratories has led to significant growth in interest in suspension array technologies (SATs), especially with regard to cytometric assays targeting a low to medium number of analytes. Such SAT or bead-based assays rely on spherical objects that constitute the analytical platform. Usually, functionalized polymer or silica (SiO2) microbeads are used which each have distinct advantages and drawbacks. In this paper, we present a straightforward synthetic route to highly monodisperse SiO2-coated polystyrene core−shell (CS) beads for SAT with controllable architectures from smooth to raspberry- and multilayer-like shells by varying the molecular weight of poly(vinylpyrrolidone) (PVP), which was used as the stabilizer of the cores. The combination of both organic polymer core and a structurally controlled inorganic SiO2 shell in one hybrid particle holds great promises for flexible next-generation design of the spherical platform. The particles were characterized by electron microscopy (SEM, T-SEM, and TEM), thermogravimetry, flow cytometry, and nitrogen adsorption/desorption, offering comprehensive information on the composition, size, structure, and surface area. All particles show ideal cytometric detection patterns and facile handling due to the hybrid structure. The beads are endowed with straightforward modification possibilities through the defined SiO2 shells. We successfully implemented the particles in fluorometric SAT model assays, illustrating the benefits of tailored surface area which is readily available for small-molecule anchoring. Very promising assay performance was shown for DNA hybridization assays with quantification limits down to 8 fmol. Washington, DC, USA American Chemical Society American Chemical Society 2016 Langmuir 32 15 3717 3727 DOI: 10.1021/acs.langmuir.6b00373 2016-04-27 OPUS4-34469 Zeitschriftenartikel Lempke, L.; Fischer, Tobias; Bell, Jérémy; Kraus, Werner; Rurack, Knut; Krause, N. Gold-catalyzed allene cycloisomerization for pyrrole synthesis: towards highly fluorinated BODIPY dyes A novel synthetic strategy toward highly fluorinated BODIPY dyes with exceptional photostabilities relying on sustainable gold catalysis has been developed. A key to the tailored pyrrole precursors is the gold catalysis performed in ionic liquids as the reaction medium, allowing a facile recycling of the catalysts. The dyes prepared are well-matching with the spectral windows of popular rhodamine dyes and possess high brightness while showing a distinctly higher photostability than the rhodamines especially in aprotic solvents. Cambridge RSC 2015 Organic & biomolecular chemistry 13 12 3787 3791 urn:nbn:de:kobv:b43-344692 10.1039/c4ob02671c http://creativecommons.org/licenses/by/3.0/de/deed.de 2016-02-20 OPUS4-34470 Zeitschriftenartikel Fischer, Tobias; Dietrich, Paul; Streeck, C.; Ray, S.; Nutsch, A.; Shard, A.; Beckhoff, B.; Unger, Wolfgang; Rurack, Knut Quantification of variable functional-group densities of mixed-silane monolayers on surfaces via a dual-mode fluorescence and XPS label The preparation of aminated monolayers with a controlled density of functional groups on silica surfaces through a simple vapor deposition process employing different ratios of two suitable monoalkoxysilanes, (3-aminopropyl)diisopropylethoxysilane (APDIPES) and (3-cyanopropyl)dimethylmethoxysilane (CPDMMS), and advances in the reliable quantification of such tailored surfaces are presented here. The one-step codeposition process was carried out with binary silane mixtures, rendering possible the control over a wide range of densities in a single step. In particular, APDIPES constitutes the functional silane and CPDMMS the inert component. The procedure requires only small amounts of silanes, several ratios can be produced in a single batch, the deposition can be carried out within a few hours and a dry atmosphere can easily be employed, limiting self-condensation of the silanes. Characterization of the ratio of silanes actually bound to the surface can then be performed in a facile manner through contact angle measurements using the Cassie equation. The reliable estimation of the number of surface functional groups was approached with a dual-mode BODIPY-type fluorescence label, which allows quantification by fluorescence and XPS on one and the same sample. We found that fluorescence and XPS signals correlate over at least 1 order of magnitude, allowing for a direct linking of quantitative fluorescence analysis to XPS quantification. Employment of synchrotron-based methods (XPS; reference-free total reflection X-ray fluorescence, TXRF) made the traceable quantification of surface functional groups possible, providing an absolute reference for quantitative fluorescence measurements through a traceable measurement chain. Washington, DC American Chemical Society 2015 Analytical chemistry 87 5 2685 2692 10.1021/ac503850f 2016-02-20 OPUS4-49218 Zeitschriftenartikel Bartelmeß, Jürgen; Valderrey, Virginia; Rurack, Knut Development of a "Turn-on" Fluorescent Probe-Based Sensing System for Hydrogen Sulfide in Liquid and Gas Phase A "turn-on" fluorescence sensing system based on a BODIPY-cobaloxime complex for the detection of H2S in liquid and gas phase was developed. To that aim, two cobaloxime complexes bearing an axial pyridyl-BODIPY ligand were initially evaluated as sensitive fluorescent HS− indicators in aqueous solution. The sensing mechanism involves the selective substitution of the BODIPY ligand by the HS− anion at the cobalt center, which is accompanied by a strong fluorescence enhancement. The selection of a complex with an ideal stability and reactivity profile toward HS− relied on the optimal interaction between the cobalt metal-center and two different pyridyl BODIPY ligands. Loading the best performing BODIPY-cobaloxime complex onto a polymeric hydrogel membrane allowed us to study the selectivity of the probe for HS− against different anions and cysteine. Successful detection of H2S by the fluorescent "light-up" membrane was not only accomplished for surface water but could also be demonstrated for relevant H2S concentrations in gas phase. Lausanne Frontiers Media 2019 Frontiers in Chemistry 7 Art. Nr. 641 urn:nbn:de:kobv:b43-492186 10.3389/fchem.2019.00641 https://creativecommons.org/licenses/by/4.0/deed.de 2019-10-09 OPUS4-49305 Zeitschriftenartikel Carl, Peter; Sarma, Dominik; Gregório, Bruno J. R.; Hoffmann, Kristin; Lehmann, Andreas; Rurack, Knut; Schneider, Rudolf Wash-Free Multiplexed Mix-and-Read Suspension Array Fluorescence Immunoassay for Anthropogenic Markers in Wastewater Pharmaceuticals, certain food ingredients, and mammalian endogenous metabolic products in wastewater are mostly of human origin. They are anthropogenic markers. Proper knowledge of their levels in wastewater helps to track sources of pollutants in natural waters and allows for calculation of removal efficiencies in wastewater Treatment plants. Here, we describe the development and application of an indirect competitive, multiplexing suspension Array fluorescence immunoassay (SAFIA) for the detection of carbamazepine (CBZ), diclofenac (DCF), caffeine (CAF), and isolithocholic acid (ILA) in wastewater, covering those classes of anthropogenic markers. The assay consists of haptens covalently conjugated to fluorescence-encoded polystyrene core/silica shell microparticles to create a site for competitive binding of the antibodies (Abs). Bound Abs are then stained with fluorophore-labeled Abs. Encoding and signaling fluorescence of the particles are determined by an automated flow cytometer. For compatibility of the immunoassay with the 96-well microtiter plate format, a stop reagent, containing formaldehyde, is used. This enables a wash-free procedure while decreasing time-to-result. Detection limits of 140 ± 40 ng/L for CBZ, 180 ± 110 ng/L for CAF, 4 ± 3 ng/L for DCF, and 310 ± 70 ng/L for ILA are achieved, which meet the sensitivity criteria of wastewater analysis. We demonstrate the applicability of SAFIA to real wastewater samples from three different wastewater Treatment plants, finding the results in good agreement with LC-MS/MS. Moreover, the accuracy in general exceeded that from classical ELISAs. We therefore propose SAFIA as a quick and reliable approach for wastewater analysis meeting the requirements for process analytical technology. ACS Publications American Chemical Society 2019 Analytical Chemistry 91 20 12988 12966 10.1021/acs.analchem.9b03040 2019-10-24 OPUS4-50756 Zeitschriftenartikel Costa, Elena; Climent Terol, Estela; Ast, S.; Weller, Michael G.; Canning, J.; Rurack, Knut Development of a lateral flow test for rapid pyrethroid detection using antibody-gated indicator-releasing hybrid materials The employment of type-I pyrethroids for airplane disinfection in recent years underlines the necessity to develop sensing schemes for the rapid detection of these pesticides directly at the point-of-use. Antibody-gated indicator-releasing materials were thus developed and implemented with test strips for lateral-flow assay-based analysis employing a smartphone for readout. Besides a proper matching of pore sizes and gating macromolecules, the functionalization of both the material's outer surface as well as the strips with PEG chains enhanced system performance. This simple assay allowed for the detection of permethrin as a target molecule at concentrations down to the lower ppb level in less than 5 minutes. Cambridge Royal Society of Chemistry 2020 Analyst 145 10 3490 3494 10.1039/d0an00319k 2020-05-13 OPUS4-48319 Zeitschriftenartikel Abdelshafi, Nahla A.; Bell, Jérémy; Rurack, Knut; Schneider, Rudolf Microfluidic electrochemical immunosensor for the trace analysis of cocaine in water and body fluids Quick but accurate testing and on-the-spot monitoring of cocaine in oral fluids and urine continues to be an important toxicological issue. In terms of drug testing, a number of devices have been introduced into the market in recent decades, notably for workplace inspection or roadside testing. However, these systems do not always fulfill the requirements in terms of reliability, especially when low cut-off levels are required. With respect to surface water, the presence of anthropogenic small organic molecules such as prescription and over-the-counter pharmaceuticals as well as illicit drugs like cannabinoids, heroin, or cocaine, has become a challenge for scientists to develop new analytical tools for screening and on-site analysis because many of them serve as markers for anthropogenic input and consumer behavior. Here, a modular approach for the detection of cocaine is presented, integrating an electrochemical enzyme-linked immunosorbent assay (ELISA) performed on antibody-grafted magnetic beads in a hybrid microfluidic sensor utilizing flexible tubing, static chip and screen-printed electrode (SPE) elements for incubation, recognition, and cyclic voltammetry measurements. A linear response of the sensor vs. the logarithm of cocaine concentration was obtained with a limit of detection of 0.15 ng/L. Within an overall assay time of 25 minutes, concentrations down to 1 ng/L could be reliably determined in water, oral fluids, and urine, the system possessing a dynamic working range up to 1 mg/L. Weinheim Wiley 2018 Drug Testing and Analysis 11 492 500 10.1002/dta.2515 2019-06-26 OPUS4-49393 Zeitschriftenartikel Tillo, Adam; Bartelmeß, Jürgen; Chauhan, Vraj P.; Bell, Jérémy; Rurack, Knut Microfluidic Device for the Determination of Water Chlorination Levels Combining a Fluorescent meso-Enamine Boron Dipyrromethene Probe and a Microhydrocyclone for Gas Bubble Separation Chlorination procedures are commonly applied in swimming pool water and wastewater treatment, yet also in food, pharmaceutical, and paper production. The amount of chlorine in water needs to be strictly controlled to ensure efficient killing of pathogens but avoid the induction of negative health effects. Miniaturized microfluidic fluorescence sensors are an appealing approach here when aiming at online or at-site measurements. Two meso-enamine-substituted boron dipyrromethene (BODIPY) dyes were found to exhibit favorable indication properties, their reaction with hypochlorite leading to strong fluorescence enhancement. Real-time assays became possible after integration of these fluorescent probes with designed two-dimensional (2D) and three-dimensional (3D) microfluidic chips, incorporating a passive sinusoidal mixer and a microhydrocyclone, respectively. A comparison of the two microfluidic systems, including their abilities to prevent accumulation or circulation of microbubbles produced by the chemical indication reaction, showed excellent fluidic behavior for the microhydrocyclone-based device. After coupling to a miniaturized optical reader for fluorescence detection, the 2D microfluidic system showed a promising detection range of 0.04−0.5 mg L−1 while still being prone to bubble-induced fluctuations and suffering from considerably low signal gain. The microhydrocyclone-based system was distinctly more robust against gas bubbles, showed a higher signal gain, and allowed us to halve the limit of detection to 0.02 mg L−1. The use of the 3D system to quantify the chlorine content of swimming pool water samples for sensitive and quantitative chlorine monitoring was demonstrated. Washington, DC American Chemical Society 2019 Analytical Chemistry 91 20 12980 12987 10.1021/acs.analchem.9b03039 2019-10-28 OPUS4-51842 Zeitschriftenartikel Climent Terol, Estela; Biyikal, Mustafa; Gröninger, Delia; Weller, Michael G.; Martínez Mánez, R.; Rurack, Knut Climent Terol, Estela Multiplexed Detection of Analytes on Single Test Strips with Antibody-Gated Indicator-Releasing Mesoporous Nanoparticles Rapid testing methods for the use directly at apointof need are expected to unfold their true potential especiallywhen offering adequate capabilities for the simultaneousmeasurement of multiple analytes of interest. Considering theunique modularity,high sensitivity,and selectivity of antibody-gated indicator delivery (gAID) systems,amultiplexed assayfor three small-molecule explosives (TATP, TNT,PETN) wasthus developed, allowing to detect the analytes simultaneouslywith asingle test strip at lower ppb concentrations in the liquidphase in < 5min using afluorescence reader or asmartphonefor readout. While the TNT and PETN systems were newlydeveloped here,all the three systems also tolerated harshermatrices than buffered aqueous model solutions.Besidesasingle-track strip,the outstanding modularity of the hybridbiosensor materials in combination with strip-patterningtechnologies allowed us to obtain amultichannel strip inastraightforwardmanner,offering comparable analyticalperformance while allowing to be tailored even more to theusersneed. Weinheim Wiley-VCH 2020 Angewandte Chemie - International Edition 59 52 23862 23869 urn:nbn:de:kobv:b43-518424 10.1002/anie.202009000 https://creativecommons.org/licenses/by/4.0/deed.de 2020-12-16 OPUS4-51843 Zeitschriftenartikel Climent Terol, Estela; Biyikal, Mustafa; Gröninger, Delia; Weller, Michael G.; Martínez Mánez, R.; Rurack, Knut Multiplex-Nachweis von Analyten auf einem einzelnen Teststreifen mit Antikörper-gesteuerten und Indikator freisetzenden mesoporösen Nanopartikeln Vor dem Hintergrund der einzigartigen Modularität, hohen Empfindlichkeit und Selektivität von Antikörper-gesteuerten Indikatorfreisetzungssystemen (gAID-Systemen) wurde hier ein Multiplex-Assay für drei organische Explosivstoffmoleküle (TATP, TNT, PETN) entwickelt, der es erlaubt, die Analyten gleichzeitig in flüssiger Phase mit einem einzelnen Teststreifen und einem Fluoreszenzlesegerät bzw. Smartphone als Detektor in Konzentrationen bis in den unteren ppb-Bereich in <5 min nachzuweisen. Alle drei Systeme, darunter die hier neu entwickelten Systeme für TNT und PETN, tolerieren zudem nicht nur gepufferte wässrige Modelllösungen, sondern auch komplexere Matrices. Neben einem konventionellen Teststreifen mit einem Kanal erlaubte uns die Anwendung von Wachsdrucktechnologie das Herstellen von mehrkanaligen Streifen mit vergleichbarer analytischer Leistungsfähigkeit, was das enorme Potenzial der modular aufgebauten, hybriden Biosensormaterialien im Hinblick auf eine für den Endanwender maßgeschneiderte Vor-Ort-Analytik unterstreicht. Weinheim Wiley-VCH 2020 Angewandte Chemie 132 52 24071 24078 urn:nbn:de:kobv:b43-518431 10.1002/ange.202009000 https://creativecommons.org/licenses/by/4.0/deed.de 2020-12-16 OPUS4-51705 Zeitschriftenartikel Costa, Elena; Climent Terol, Estela; Gawlitza, Kornelia; Wan, Wei; Weller, Michael G.; Rurack, Knut Optimization of analytical assay performance of antibody-gated indicator-releasing mesoporous silica particles Antibody-gated indicator delivery (gAID) systems based on mesoporous silica nano- and microparticle scaffolds are a promising class of materials for the sensitive chemical detection of small-molecule analytes in simple test formats such as lateral flow assays (LFAs) or microfluidic chips. Their architecture is reminiscent of drug delivery systems, only that reporter molecules instead of drugs are stored in the voids of a porous host particle. In addition, the pores are closed with macromolecular "caps" through a tailored "gatekeeping" recognition chemistry so that the caps are opened when an analyte has reacted with a "gatekeeper". The subsequent uncapping leads to a release of a large number of indicator molecules, endowing the system with signal amplification features. Particular benefits of such systems are their modularity and adaptability. With the example of the immunochemical detection of type-I pyrethroids by fluorescent dye-releasing gAID systems, the influence of several tuning modes on the optimisation of such hybrid sensory materials is introduced here. In particular, different mesoporous silica supports (from nano- and microparticles to platelets and short fibres), different functionalisation routes and different loading sequences were assessed. The materials' performances were evaluated by studying their temporal response behaviour and detection sensitivity, including the tightness of pore closure (through the amount of blank release in the absence of analyte) and the release kinetics. Our results indicate that the better the paratope-accommodating Fab region of the antibody "cap" fits into the host material's pore opening, the better the closing/opening mechanism can be controlled. Because such materials are well-suited for LFAs, performance assessment included a test-strip format besides conventional assays in suspension. In combination with dyes as indicators and smartphones for read-out, simple analytical tests for use by untrained personnel directly at a point-of-need such as an aeroplane cabin can be devised, allowing for sensitivities down to the μg kg−1 range in <5 min with case-required selectivities. Royal Society of Chemistry 2020 Journal of Materials Chemistry B 8 22 4950 4961 urn:nbn:de:kobv:b43-517053 10.1039/d0tb00371a https://creativecommons.org/licenses/by/4.0/deed.de 2020-12-02 OPUS4-51566 Zeitschriftenartikel Bierstedt, Andreas; Warschat, Carsten; You, Yi; Rurack, Knut; Riedel, Jens Stimulated Raman scattering by intracavity mixing of nanosecond laser excitation and fluorescence in acoustically levitated droplets Raman spectroscopy is becoming a commonly used, powerful tool for structural elucidation and species identification of small liquid samples, e.g. in droplet-based digital microfluidic devices. Due to the low scattering cross sections and the temporal restrictions dictated by the droplet flow, however, it depends on amplification strategies which often come at a cost. In the case of surface-enhanced Raman scattering (SERS), this can be an enhanced susceptibility towards memory effects and cross talk, whereas resonant and/or stimulated Raman techniques require higher instrumental sophistication, such as tunable lasers or the high electromagnetic field strengths which are typically provided by femtosecond lasers. Here, an alternative instrumental approach is discussed, in which stimulated Raman scattering (SRS) is achieved using the single fixed wavelength output of an inexpensive diode-pumped solid-state (DPSS) nanosecond laser. The required field strengths are realized by an effective light trapping in a resonator mode inside the interrogated droplets, while the resonant light required for the stimulation is provided by the fluorescence signal of an admixed laser dye. To elucidate the underlying optical processes, proof-of-concept experiments are conducted on acoustically levitated droplets, mimicking a highly reproducible and stable digital fluidic system. By using isotope-labeled compounds, the assignment of the emitted radiation as Raman scattering is firmly corroborated. A direct comparison reveals an amplification of the usually weak spontaneous Stokes emission by up to five orders of magnitude. Further investigation of the optical power dependence reveals the resulting gain to depend on the intensity of both, the input laser fluence and the concentration of the admixed fluorophore, leaving SRS as the only feasible amplification mechanism. While in this study stable large droplets have been studied, the underlying principles also hold true for smaller droplets, in which case significantly lower laser pulse energy is required. Since DPSS lasers are readily available with high repetition rates, the presented detection strategy bears a huge potential for fast online identification and characterization routines in digital microfluidic devices. Royal Society of Chemistry 2020 Analytical Methods 12 42 5046 5054 10.1039/D0AY01504K 2020-11-16 OPUS4-49835 Zeitschriftenartikel Liu, H.; Song, W.; Gröninger, Delia; Zhang, L.; Lu, Y.; Chan, K. S.; Zhou, Z.; Rurack, Knut; Shen, Z. Real-time monitoring of newly acidified organelles during autophagy enabled by reaction-based BODIPY dyes Real-time monitoring of newly acidified organelles during autophagy in living cells is highly desirable for a better understanding of intracellular degradative processes. Herein, we describe a reaction-based boron dipyrromethene (BODIPY) dye containing strongly electron-withdrawing diethyl 2-cyanoacrylate groups at the α-positions. The probe exhibits intense red fluorescence in acidic organelles or the acidified cytosol while negligible fluorescence in other regions of the cell. The underlying mechanism is a nucleophilic reaction at the central meso-carbon of the indacene core, resulting in the loss of π-conjugation entailed by dramatic spectroscopic changes of more than 200 nm between its colorless, non-fluorescent leuco-BODIPY form and its red and brightly emitting form. The reversible transformation between red fluorescent BODIPY and leuco-BODIPY along with negligible cytotoxicity qualifies such dyes for rapid and direct intracellular lysosome imaging and cytosolic acidosis detection simultaneously without any washing step, enabling the real-time monitoring of newly acidified organelles during autophagy. London Nature Research 2019 Communications Biology 2 442 urn:nbn:de:kobv:b43-498358 10.1038/s42003-019-0682-1 https://creativecommons.org/licenses/by/4.0/deed.de 2019-12-02 OPUS4-49777 Zeitschriftenartikel Descalzo, Ana B.; Ashokkumar, Pichandi; Shen, Z.; Rurack, Knut On the Aggregation Behaviour and Spectroscopic Properties of Alkylated and Annelated BoronDipyrromethene (BODIPY) Dyes in Aqueous Solution The tendency of boron-dipyrromethene (BODIPY) dyes to associate in water is well known, and usually a cause for inferior fluorescence properties. Synthetic efforts to chemically improve BODIPYs' water solubility and minimize this problem have been numerous in the past. However, a deeper understanding of the phenomena responsible for fluorescence quenching is still required. Commonly, the spectroscopic behaviour in aqueous media has been attributed to aggregate or excimer formation, with such works often centring on a single BODIPY family. Herein, we provide an integrating discussion including very diverse types of BODIPY dyes. Our studies revealed that even subtle structural changes can distinctly affect the association behaviour of the fluorophores in water, involving different photophysical processes. The palette of behaviour found ranges from unperturbed emission, to the formation of H or J aggregates and excimers, to the involvement of tightly bound, preformed excimers. These results are a first step to a more generalized understanding of spectroscopic properties vs. structure, facilitating future molecular design of BODIPYs, especially as probes for biological applications. Weinheim WILEY-VCH 2019 ChemPhotoChem 4 2 120 131 urn:nbn:de:kobv:b43-497771 10.1002/cptc.201900235 https://creativecommons.org/licenses/by/4.0/deed.de 2019-11-27 OPUS4-51955 Zeitschriftenartikel Tobias, Charlie; Climent Terol, Estela; Gawlitza, Kornelia; Rurack, Knut Polystyrene Microparticles with Convergently Grown Mesoporous Silica Shells as a Promising Tool for Multiplexed Bioanalytical Assays Functional core/shell particles are highly sought after in analytical chemistry, especially in methods suitable for single-particle analysis such as flow cytometry because they allow for facile multiplexed detection of several analytes in a single run. Aiming to develop a powerful bead platform of which the core particle can be doped in a straightforward manner while the shell offers the highest possible sensitivity when functionalized with (bio)chemical binders, polystyrene particles were coated with different kinds of mesoporous silica shells in a convergent growth approach. Mesoporous shells allow us to obtain distinctly higher surface areas in comparison with conventional nonporous shells. While assessing the potential of narrow- as well as wide-pore silicas such as Mobil composition of matter no. 41 (MCM-41) and Santa Barbara amorphous material no. 15 (SBA-15), especially the synthesis of the latter shells that are much more suitable for biomolecule anchoring was optimized by altering the pH and both, the amount and type of the mediator salt. Our studies showed that the best performing material resulted from a synthesis using neutral conditions and MgSO4 as an ionic mediator. The analytical potential of the particles was investigated in flow cytometric DNA assays after their respective functionalization for individual and multiplexed detection of short oligonucleotide strands. These experiments revealed that a two-step modification of the silica surface with amino silane and succinic anhydride prior to coupling of an amino-terminated capture DNA (c-DNA) strand is superior to coupling carboxylic acid-terminated c-DNA to aminated core/shell particles, yielding limits of detection (LOD) down to 5 pM for a hybridization assay, using labeled complementary single-stranded target DNA (t-DNA) 15mers. The potential of the use of the particles in multiplexed analysis was shown with the aid of dye-doped core particles carrying a respective SBA-15 shell. Characteristic genomic sequences of human papillomaviruses (HPV) were chosen as the t-DNA analytes here, since their high relevance as carcinogens and the high number of different pathogens is a relevant model case. The title particles showed a promising performance and allowed us to unequivocally detect the different high- and low-risk HPV types in a single experimental run. Washington, DC American Chemical Society 2020 ACS Applied Materials & Interfaces 13 1 207 218 10.1021/acsami.0c17940 2021-01-06 OPUS4-51956 Zeitschriftenartikel Climent Terol, Estela; Gotor, Raul; Tobias, Charlie; Bell, Jérémy; Martin-Sanchez, Pedro; Rurack, Knut Dip Sticks Embedding Molecular Beacon-Functionalized Core−Mesoporous Shell Particles for the Rapid On-Site Detection of Microbiological Fuel Contamination Microbial contamination of fuels by fungi and bacteria presents risks of corrosion and fuel system fouling. In this work, a rapid test for the determination of microbial genomic DNA from aqueous fuel extracts is presented. It combines test strips coated with polystyrene core/mesoporous silica shell particles, to the surface of which modified fluorescent molecular beacons are covalently grafted, with a smartphone detection system. In the hairpin loop, the beacons incorporate a target sequence highly conserved in all bacteria, corresponding to a fragment of the 16S ribosomal RNA gene, which is also present to a significant extent in the 18S rRNA gene of fungi, allowing for broadband microbial detection. In the developed assay, the presence of genomic DNA extracts from bacteria and fungi down to ca. 20−50 μg L−1 induced a distinct fluorescence response. The optical read-out was adapted for on-site monitoring by combining a 3D-printed case with a conventional smartphone, taking advantage of the sensitivity of contemporary complementary metal oxide semiconductor (CMOS) detectors. Such an embedded assembly allowed to detect microbial genomic DNA in aqueous extracts down to ca. 0.2−0.7 mg L−1 and presents an important step toward the on-site uncovering of fuel contamination in a rapid and simple fashion. Washington, DC American Chemical Society 2020 ACS Sensors 6 1 27 34 10.1021/acssensors.0c01178 2021-01-06 OPUS4-52521 Zeitschriftenartikel Kimani, Martha Wamaitha; Beyer, S.; El-Schich, Z.; Gawlitza, Kornelia; Rurack, Knut; Gjörloff-Wingren, A. Imprinted Particles for Direct Fluorescence Detection of Sialic Acid in Polar Media and on Cancer Cells with Enhanced Control of Nonspecific Binding Glycoproteins are abundant on the cell surface of mammals, providing structural support, modulating cell Membrane properties, and acting as signaling agents. Variation of glycosylation patterns has been found to indicate various disease states, including cell malignancy. Sialic acid (SA) is present as a terminating group on cell-surface glycans, and its overexpression has been linked to several types of cancer. Detection of SA on the cell surface is therefore critical for detection of cancer in its early stages. In this work, a fluorescent molecularly imprinted polymer layer targeting SA was synthesized on the surface of silica-coated polystyrene (PS) particles. Compared to previous works, a PS core supplies a lighter, lower-density support for improved suspension stability and scattering properties. Moreover, their smaller size provides a higher surface-area-to-volume ratio for binding. The incorporation of a fluorescent monomer in the MIP shell allowed for simple and rapid determination of binding specificity in polar media due to a deprotonation−reprotonation interaction mechanism between the fluorescent monomer and SA, which led to spectral changes. Upon titration of the MIP particles with SA in suspension, an increase in fluorescence emission of the particles was observed, with the MIP particles binding SA more selectively compared to the nonimprinted polymer (NIP) control particles. In cell staining experiments performed by flow cytometry, the binding behavior of the MIP particles compared favorably with that of SA-binding lectins. NIPs prepared with a "dummy" template served as a better negative control in cell binding assays due to the favorable inward orientation of template-binding functional groups in the polymer shell, which reduced nonspecific binding. The results show that fluorescent MIPs targeting SA are a promising tool for in vitro fluorescence staining of cancerous cells and for future diagnosis of cancer at early stages. American Chemical Society 2021 ACS Applied Polymer Materials 3 5 2363 2373 urn:nbn:de:kobv:b43-525216 10.1021/acsapm.0c01353 https://creativecommons.org/licenses/by-nc-nd/4.0/deed.de 2021-04-28 OPUS4-43100 Zeitschriftenartikel Descalzo, Ana B.; Xu, H.-J.; Shen, Z.; Rurack, Knut Influence of the meso-substituent on strongly red emitting phenanthrene-fused boron-dipyrromethene (BODIPY) fluorophores with a propeller-like conformation Highly emissive phenanthrene-fused boron-dipyrromethene (PBDP) dyes have been spectroscopically characterized in a series of solvents. The influence of different substituents (-H, -I, -CN, -DMA or a 15C5-crown ether) in the para-position of a phenyl ring attached to the meso-position of the BODIPY core is discussed. This family of dyes has an intense emission at lambda > 630 nm, with fluorescence quantum yields between 0.7 and 1.0 in all solvents studied, except in the case of the dimethylamino-substituted derivative, PBDP-DMA, which undergoes excited-state intramolecular charge transfer (CT), leading to broadband dual fluorescence in highly polar solvents. Introduction of a weaker electron donor such as a benzocrown to the meso-position is not able to trigger a second (charge or electron transfer) process and, interestingly, heavy atom (iodine, PBDP-I derivative) substitution at that moiety does also not have a relevant influence on the photophysics, i.e., enhanced intersystem crossing was not observed. Electrochemical studies of PBDP-DMA complement the data reported and stress the fact that the decrease in fluorescence of PBDP-DMA in highly polar solvents is due to an excited-state CT process rather than to a photoinduced electron transfer (PET). Amsterdam Elsevier 2018 Journal of Photochemistry and Photobiology A: Chemistry 352 98 105 10.1016/j.jphotochem.2017.10.034 2017-11-24 OPUS4-43101 Zeitschriftenartikel Wan, Wei; Descalzo, Ana B.; Shinde, S.; Weißhoff, Hardy; Orellana, G.; Sellergren, B.; Rurack, Knut Ratiometric fluorescence detection of phosphorylated amino acids through excited-state proton transfer by using molecularly imprinted polymer (MIP) recognition nanolayers A 2,3-diaminophenazine bis-urea fluorescent probe monomer (1) was developed. It responds to phenylphosphate and phosphorylated amino acids in a ratiometric fashion with enhanced fluorescence accompanied by the development of a redshifted emission band arising from an excited-state proton transfer (ESPT) process in the hydrogen-bonded probe/analyte complex. The two urea groups of 1 form a cleft-like binding pocket (Kb>10^10 L^2 mol^-2 for 1:2 complex). Imprinting of 1 in presence of ethyl ester- and fluorenylmethyloxycarbonyl (Fmoc)-protected phosphorylated tyrosine (Fmoc-pTyr-OEt) as the template, methacrylamide as co-monomer, and ethyleneglycol dimethacrylate as crosslinker gave few-nanometer-thick molecularly imprinted polymer (MIP) shells on silica core microparticles with excellent selectivity for the template in a buffered biphasic assay. The supramolecular recognition Features were established by spectroscopic and NMR studies. Rational screening of comonomers and cross-linkers allowed to single out the best performing MIP components, giving significant imprinting factors (IF>3.5) while retaining ESPT emission and the ratiometric response in the thin polymer shell. Combination of the bead-based detection scheme with the phase-transfer assay dramatically improved the IF to 15.9, allowing sensitive determination of the analyte directly in aqueous media. Weinheim Wiley-VCH 2017 Chemistry - A European Journal 23 63 15974 15983 10.1002/chem.201703041 2017-11-24 OPUS4-43102 Zeitschriftenartikel Ashokkumar, Pichandi; Bell, Jérémy; Buurman, Merwe; Rurack, Knut Analytical platform for sugar sensing in commercial beverages using a fluorescent BODIPY "light-up" probe Because of the globally increasing prevalence of diabetes, the need for accurate, efficient and at best miniaturized automated analytical systems for sugar detection in medical diagnostics and the food industry is still urgent. The development of molecular probes for sugars based on boronic acid receptors offers an excellent alternative to the kinetically slow enzyme-based sugar sensors. Moreover, by coupling such chelating units with dye scaffolds like BODIPYs (boron-dipyrromethenes), highly fluorescent sugar sensing schemes can be realized. In this work, a boronic acid-functionalized BODIPY probe was developed, which binds selectively to fructose's adjacent diols to form cyclic boronate esters. Placement of an amino group in direct neighborhood of the boronic acid moiety allowed us to obtain a broad working range at neutral pH, which distinguishes the probe from the majority of systems working only at pH > 8, while still meeting the desired sensitivity in the micro-molar range due to a pronounced analyte-induced fluorescence increase. To enhance the applicability of the test in the sense described above, integration with a microfluidic chip was achieved. Here, fructose was selectively detected by fluorescence with similar sensitivity in real time on chip, and an assay for the straightforward detection of sugar in (colored) sodas without sample clean-up was established. Amsterdam Elsevier 2018 Sensors and Actuators B: Chemical 256 609 615 10.1016/j.snb.2017.09.201 2017-11-24 OPUS4-43103 Zeitschriftenartikel Gotor, Raúl; Tiebe, Carlo; Schlischka, Jörg; Bell, Jérémy; Rurack, Knut Detection of adulterated diesel using fluorescent test strips and smartphone readout The fluorescence properties of three molecular rotors, related to 4-dimethylamino-4-nitrostilbene (4-DNS), are studied versus different diesel/kerosene blends. In nonviscous solvents, these compounds can populate a twisted intramolecular charge transfer state which deactivates nonradiatively, successfully suppressing fluorescence emission. Solution experiments with diesel/kerosene blends showed a good linear correlation between the fluorescence intensity of the probe molecules and the diesel fraction of the blend. The dyes have been immobilized on paper, retaining their fluorescence behavior, i.e., negligible emission in the presence of nonviscous organic solvents and increasing fluorescence when the environment is increasingly viscous. When the impregnated paper is devised as a test strip, the latter is compatible with a newly designed smartphone reader system, which allows in-the-field measurements. The method can safely detect the presence of kerosene in diesel at ≥7%, which competes favorably with current standard methods for the detection of diesel adulteration. Washington, D.C. American Chemical Society 2017 Energy & Fuels 31 11 11594 11600 10.1021/acs.energyfuels.7b01538 2017-11-24 OPUS4-43352 Beitrag zu einem Tagungsband Gawlitza, Kornelia; Tiebe, Carlo; Banach, Ulrich; Noske, Reinhard; Bartholmai, Matthias; Rurack, Knut Novel sensor for long-term monitoring of ammonia in gas phase Because ammonia and its reaction products can cause considerable damage to human health and ecosystems, there is a need for reliably operating and reversibly interacting sensor materials to monitor traces of gaseous ammonia in ambient air, which at best can be used on-site for in-the-field measurements. Herein, the development of a sensor material for gaseous ammonia in the lower ppm to ppb range using optical fluorescence as transduction mechanism is presented. A fluorescent dye, which shows reversible fluorescence enhancement in the presence of ammonia is incorporated into a polymer matrix, the latter to ensure the accumulation of ammonia. The sensor material is integrated into a prototype of a miniaturized sensor device, facilitating long-term operation. To calibrate the optical sensor system a gas standard generator, producing standard gas mixtures, is used, leading to a sensitivity down to lower ppm concentrations of ammonia. 2017 13. Dresdner Sensor-Symposium 2017 13. Dresdner Sensor-Symposium 2017 Dresden, Germany 04.12.2017 06.12.2017 P4.02, 272 276 10.5162/13dss2017/P4.02 2017-12-07 OPUS4-43209 Posterpräsentation Bartelmeß, Jürgen; Gawlitza, Kornelia; Bartholmai, Matthias; Rurack, Knut Developments towards the fluorescence based sensing of hazardous gases Fluorescence based sensing is a versatile approach for the trace analysis outside of the laboratory, requiring suitable sensor materials and their integration into sensing devices. The versatility of fluorophores as probes, especially in terms of the possibility to tailor their optical as well as their recognition properties by synthetic modifications in a wide range, renders them a superior active component for the preparation of optical sensor devices. Recent works at BAM in this field include, for example, the detection of nerve gas agents, illustrating impressively the aforementioned benefits of fluorophores in optical sensing applications. In the interdisciplinary approach presented here, we target hazardous gases such as ammonia, benzene, and hydrogen sulfide, next to others, which pose a major threat to human health and environmental safety and for which the availability of a sensitive and reliable detection method is highly desirable. The dyes presented follow a "turn-on" fluorescence schematic which allows for the selective and sensitive detection of the respective gaseous analyte. The immobilization of the probe in polymeric matrices is then the next step toward the fabrication of a prototype device for molecular sensing. 2017 Colloquium of Optical Spectrometry (COSP) 2017 Berlin, Germany 27.11.2017 29.11.2017 2017-12-01 OPUS4-43767 Zeitschriftenartikel Gawlitza, Kornelia; Fischer, Tobias; Rurack, Knut Chemical functionalization for quantitative spectroscopic labeling on macroscopically flat surfaces This chapter highlights the application of chemical derivatization (CD) to facilitate the quantification of surface functional groups being an important issue for a wide field of applications. The selective attachment of a chemical label to a surface functional group being afterwards exclusively detectable by a highly sensitive technique overcomes the problem of characterizing low amounts of functional groups on macroscopically flat surfaces. The most frequently employed methods include CD X-ray photoelectron spectroscopy, ultraviolet/visible absorption, and fluorescence spectroscopy, as well as time-of-flight secondary ion mass spectrometry. Herein, the basic conditions for the different techniques regarding the specific surface functional group which need to be quantified are discussed. Additionally, the substrate highly influences the compatibility of the corresponding method. Because not just the quantification but also the preparation of the desired application is important, a summary of different preparation methods for glass, polymer and gold substrates is presented. Elsevier 2018 Reference Module in Chemistry, Molecular Sciences and Chemical Engineering 978-0-12-409547-2 1 10.1016/B978-0-12-409547-2.13191-9 2018-01-15 OPUS4-39739 Zeitschriftenartikel Climent Terol, Estela; Biyikal, Mustafa; Gawlitza, Kornelia; Dropa, T.; Urban, M.; Costero, A. M.; Martínez-Mánez, Ramon; Rurack, Knut Determination of the chemical warfare agents Sarin, Soman and Tabun in natural waters employing fluorescent hybrid silica materials A novel mesoporous silica material containing boron-dipyrromethene (BODIPY) moieties (I) is employed for the detection of nerve agent simulants (NASs) and the organophosphate nerve or chemical warfare agents (CWAs) Sarin (GB), Soman (GD), and Tabun (GA) in aqueous environments. The reactive BODIPY dye with an optimum positioned hydroxyl group undergoes acylation reactions with phosph(on)ate substrates, yielding a bicyclic ring. Due to aggregation of the dyes in water, the sensitivity of the free dye in solution is very low. Only after immobilization of the BODIPY moieties into the silica substrates is aggregation inhibited and a sensitive determination of the NASs diethyl cyanophosphonate (DCNP), diethyl chlorophosphate (DCP) and diisopropyl fluorophosphate (DFP) possible. The signaling mode is a strong quenching of the fluorescence, reaching LODs in the pM range. The best performing hybrid material was singled out from a library of hybrid silicas varying in morphology and surface functionalization. The response to actual CWAs such as GB, GD, and GA has also been tested, offering similar behavior as for the simulants. The proposed reaction mechanism has been verified by investigation of other model materials, containing for instance BODIPY moieties without an optimum hydroxyl group (III) or a BODIPY dye with an all-aliphatic counterpart (IV). The latter can only form a monocyclic reaction product, showing much less reactivity as I. Assays with other possible competitors have been additionally carried out, showing favorably low cross-reactivities. Finally, the determination of NASs in several natural waters has been demonstrated. Elsevier B.V. 2017 Sensors and Actuators B: Chemical 246 1056 1065 10.1016/j.snb.2017.02.115 2017-04-10 OPUS4-39286 Zeitschriftenartikel Ritter, B.; Haida, P.; Fink, F.; Krahl, T.; Gawlitza, Kornelia; Rurack, Knut; Scholz, G.; Kemnitz, E. Novel and easy access to highly luminescent Eu and Tb doped ultra-small CaF2, SrF2 and BaF2 nanoparticles - structure and luminescence A universal fast and easy access at room temperature to transparent sols of nanoscopic Eu3+ and Tb3+ doped CaF2, SrF2 and BaF2 particles via the fluorolytic sol-gel synthesis route is presented. Monodisperse quasi-spherical nanoparticles with sizes of 3-20 nm are obtained with up to 40% rare earth doping showing red or green luminescence. In the beginning luminescence quenching effects are only observed for the highest content, which demonstrates the unique and outstanding properties of these materials. From CaF2:Eu10 via SrF2:Eu10 to BaF2:Eu10 a steady increase of the luminescence intensity and lifetime occurs by a factor of ≈2; the photoluminescence quantum yield increases by 29 to 35% due to the lower phonon energy of the matrix. The fast formation process of the particles within fractions of seconds is clearly visualized by exploiting appropriate luminescence processes during the synthesis. Multiply doped particles are also available by this method. Fine tuning of the luminescence properties is achieved by variation of the Ca-to-Sr ratio. Co-doping with Ce3+ and Tb3+ results in a huge increase (>50 times) of the green luminescence intensity due to energy transfer Ce3+ → Tb3+. In this case, the luminescence intensity is higher for CaF2 than for SrF2, due to a lower spatial distance of the rare earth ions. Royal Society of Chemistry 2017 Dalton Transactions 46 9 2925 2936 10.1039/C6DT04711D 2017-03-06 OPUS4-45636 Zeitschriftenartikel Alnajjar, M. A.; Bartelmeß, Jürgen; Hein, R.; Ashokkumar, Pichandi; Nilam, M.; Nau, W. M.; Rurack, Knut; Hennig, A. Rational design of boron-dipyrromethene (BODIPY) reporter dyes for cucurbit[7]uril We introduce herein boron-dipyrromethene (BODIPY) dyes as a new class of fluorophores for the design of reporter dyes for supramolecular host-guest complex formation with cucurbit[7]uril (CB7). The BODIPYs contain a protonatable aniline nitrogen in the meso-position of the BODIPY chromophore, which was functionalized with known binding motifs for CB7. The unprotonated dyes show low fluorescence due to photoinduced electron transfer (PET), whereas the protonated dyes are highly fluorescent. Encapsulation of the binding motif inside CB7 positions the aniline nitrogen at the carbonyl rim of CB7, which affects the pKa value, and leads to a host-induced protonation and thus to a fluorescence increase. The possibility to tune binding affinities and pKa values is demonstrated and it is shown that, in combination with the beneficial photophysical properties of BODIPYs, several new applications of host-dye reporter pairs can be implemented. This includes indicator displacement assays with favourable absorption and emission wavelengths in the visible spectral region, fluorescence correlation spectroscopy, and noncovalent surface functionalization with fluorophores. Frankfurt a. M. Beilstein-Institut 2018 Beilstein Journal of Organic Chemistry 14 1961 1971 urn:nbn:de:kobv:b43-456361 10.3762/bjoc.14.171 https://creativecommons.org/licenses/by/4.0/deed.de 2018-08-06 OPUS4-45640 Vortrag Rurack, Knut Combining Fluorescent Probes, Functionalized Surfaces, Tailored Particles and Device Embedding for Robust, Reliable and User-friendly Analytical Assays Supramolecular chemistry, fluorescence detection, hybrid (nano)materials and device miniaturization are in themselves highly interesting areas of research, yet especially their combination paves the way to (bio)chemical analysis systems that show outstanding performance. The lecture gives an overview of the toolbox of single components developed in BAM's Chemical and Optical Sensing Division over the years, and how their combination can result in powerful sensors, quick tests and assays. While at the core of a development is the analytical problem, that is, the determination of a certain analyte in a sample of interest with the required sensitivity and selectivity by a specific end user in a given setting, signaling mechanisms, recognition elements, signal transduction modes, materials functionalization, device design and system integration are adequately chosen, tailored and adapted. Examples including molecularly imprinted polymers, hybrid mesoporous nanomaterials, gated indicator release systems, microfluidic devices, test strips and smartphone-based analysis will be presented. 2018 GDCh Chemnitz, Germany 21.06.2018 2018-08-06 OPUS4-45641 Vortrag Rurack, Knut Molecularly Imprinted Polymers with Integrated Fluorescence as Versatile Biomimetic Sensing Matrices Molecularly imprinted polymers (MIPs) are an established, versatile and high-performance matrix for the selective separation or enrichment of (bio)chemical species, especially small molecules of biochemical or environmental relevance. MIPs are prepared through the polymerization of a mixture of functional monomers and cross-linkers in the presence of the template with subsequent extraction of the latter. Conceptionally, this process can be seen as mimicking in a strongly accelerated, though single-step manner a biological process such as antibody formation. Because the resulting MIPs contain cavities in their matrix that are complementary in size, shape and electronic/ electrostatic or hydrogen bonding demand to the imprinted target molecule or template, these polymers are frequently termed "artificial antibodies". Compared to natural antibodies, they are chemically and physically much more robust. Regarding sensitivity and selectivity, however, there is still a gap to bridge before MIPs can fully compete with antibodies. Another favorable aspect that distinguishes MIPs from antibodies is that they can be endowed with an explicit function, allowing the use of MIPs in applications that require more than only an efficient binder. For instance, if specifically designed and polymerizable fluorescent indicators are integrated as functional monomers into a MIP, direct fluorescence sensing can be accomplished. Because MIPs can be prepared in a variety of different formats, their combination with miniaturized or other specific analytical techniques or sensory devices is possible, especially when the transduction mode is light. This presentation will introduce basic design considerations, challenges, limitations and the potential that lies with such sensor materials with some recent examples of our group, targeting various organic oxoanions as analytes. 2018 8th International Symposium on Bioanalysis, Biomedical Engineering and Nanotechnology Changsha, Hunan, China 25.05.2018 27.05.2018 2018-08-06 OPUS4-45642 Vortrag Rurack, Knut Integrating BODIPY Probes with Devices for On-site Sensing Applications The detection of potential contaminants as early as possible and as close to their point of emission as well as immission is becoming increasingly important in contemporary environmental analytical chemistry. In addition, real-time monitoring of important chemical parameters for process control is strongly gaining relevance within the context of Industry 4.0. Not only is the development of powerful optical probes thus necessary but also their integration into a matrix and/or device that allows for the application of such systems in realistic measurement scenarios. Integrating fluorescent probes with sensing matrices, however, presents a major challenge because usually, when confined in a rather rigid matrix, fluorophores tend to behave completely different than for instance in the molecular state in solution. The present contribution will highlight recent examples of successful integration of BODIPY (boron-dipyrromethene) based probes with devices that have been developed in our group. A simple system utilizing a test strip for direct readout with a conventional miniaturized camera as for instance routinely used in smartphones was recently devised by us for the determination of organophosphate nerve or chemical warfare agents (CWAs) Sarin (GB), Soman (GD), and Tabun (GA) in aqueous environments. Here, we coupled a reactive BODIPY to the inner and outer surface of mesoporous silica nanoparticles. In the presence of CWAs, the reactive BODIPY dye with an optimally positioned hydroxyl group undergoes an acylation reaction, yielding a bicyclic product that is non-emissive. The strong fluorescence quenching response allows reaching LODs in the pM range in natural waters. Steric embedding, again relying on test strip analysis in combination with a smartphone-based readout and data processing, was sufficient to create a reusable optical pH stick. The family of pH-responsive fluorescent BODIPY probes used for this purpose has been designed in a rational manner with the aid of quantum chemistry tools. All the probes display very similar spectroscopic properties with ON−OFF fluorescence switching responses, being retained after embedding of the probes into hydrogel sensor spots on a plastic strip. Dispensing with a matrix yet invoking microfluidic chips finally permits to use a highly sensitive boronic acid-functionalized BODIPY probe for in-line sugar analysis for instance in the beverage industry. Placement of an amino group in direct neighbourhood of the boronic acid moiety yielded a broad working range at neutral pH while meeting the desired sensitivity in the micro-molar range due to a pronounced analyte-induced fluorescence increase, guaranteeing the straightforward detection of sugar in (coloured) sodas without sample clean-up. 2018 10th International Conference on Porphyrins & Phthalocyanines Munich, Germany 01.06.2018 06.06.2018 2018-08-06 OPUS4-46567 Zeitschriftenartikel Gotor, Raúl; Rurack, Knut; Bell, Jérémy Fluorescent Paper Strips for the Detection of Diesel Adulteration with Smartphone Read-out Three fluorescent molecular rotors of 4-dimethylamino-4-nitrostilbene (4-DNS) were investigated for their potential use as viscosity probes to indicate the content of kerosene in diesel/kerosene blends, a wide-spread activity to adulterate fuel. In solvents with low viscosity, the dyes rapidly deactivate via a so-called twisted intramolecular charge transfer state, efficiently quenching the fluorescence. Measurements of diesel/kerosene blends revealed a good linear correlation between the decrease in fluorescence and the increase of the fraction of the less viscous kerosene in diesel/kerosene blends. Immobilization of the hydroxy derivative 4-DNS-OH in cellulose paper yielded test strips that preserve the fluorescent indicator's behavior. Combination of the strips with a reader based on a smartphone and a controlling app allowed to create a simple field test. The method can reliably detect the presence of kerosene in diesel from 7 to 100%, outperforming present standard methods for diesel adulteration. Cambridge, MA, USA MyJoVE Corporation 2018 Journal of Visualized Experiments 141 e58019-1 e58019-6 10.3791/58019 2018-11-14 OPUS4-47126 Zeitschriftenartikel Climent Terol, Estela; Hecht, Mandy; Witthuhn, Heike; Gawlitza, Kornelia; Rurack, Knut Cover profile for the article "Mix-&-read determination of Mercury(II) at trace levels with hybrid mesoporous silica materials incorporating fluorescent probes by a simple mix-&-load technique" Invited for this month's cover picture is the group of Dr. Knut Rurack at the Department of Analytical Chemistry; Reference Materials at the Bundesanstalt fuer Materialforschung und -pruefung (BAM) in Berlin (Germany). The cover picture shows how differences in color and fluorescence on a test strip can be easily read out with a mobile device. Two reference spots Frame the sensitive spot that indicates the presence of trace amounts of HgII below the threshold in a natural water sample. This dipstick contains a hybrid material that combines boron-dipyrromethene (BODIPY) probes sterically loaded into specifically tailored mesoporous silica particles, allowing for ultrasensitive HgII detection through enhanced fluorescence in a few seconds. The applicability in real water samples and fish extracts are also studied. Weinheim Wiley-VCH 2018 ChemistryOpen 7 12 932 933 urn:nbn:de:kobv:b43-471267 10.1002/open.201800231 https://creativecommons.org/licenses/by-nc-nd/4.0/deed.de 2019-01-02 OPUS4-47293 Zeitschriftenartikel Sarma, Dominik; Carl, Peter; Climent Terol, Estela; Schneider, Rudolf; Rurack, Knut Multifunctional polystyrene core/silica shell microparticles with antifouling properties for bead-based multiplexed and quantitative analysis Commercial bead-based assays are commonly built upon polystyrene particles. The polymeric carrier can be encoded with organic dyes and has ideal material properties for cytometric applications such as low density and high refractive index. However, functional groups are conventionally integrated during polymerization and subsequent modification is limited to the reactivity of those groups. Additionally, polystyrene as the core material leads to many hydrophobic areas still being present on the beads' surfaces even after functionalization, Rendering the particles prone to nonspecific adsorption during an application. The latter calls for several washing steps and the use of additives in (bio)analytical assays. In this contribution, we show how these limitations can be overcome by using monodisperse polystyrene (PS) core/silica (SiO2) shell particles (SiO2@PS). Two different hydrophobic BODIPY (boron−dipyrromethene) dyes were encapsulated inside a poly(vinylpyrrolidone) (PVP) -stabilized polystyrene core in different concentrations to create 5-plex arrays in two separate detection channels of a cytometer. A subsequent modification of the silica shell with an equimolar APTES/PEGS (aminopropyltriethoxysilane/polyethylene glycol silane) blend added multifunctional properties to the hybrid core/Shell microparticles in a single step: APTES provides amino groups for the attachment of a caffeine derivative (as a hapten) to create antigen-coupled microspheres; the PEG moiety effectively suppresses nonspecific binding of antibodies, endowing the surface with antifouling properties. The particles were applied in a competitive fluorescence immunoassay in suspension, and a highly selective wash-free assay for the detection of caffeine in beverages was developed as a proof of concept. Online Library American Chemical Society 2019 ACS Applied Materials and Interfaces 11 1 1321 1334 urn:nbn:de:kobv:b43-472931 10.1021/acsami.8b10306 https://creativecommons.org/licenses/by-nc-nd/4.0/deed.de 2019-01-31 OPUS4-42256 Zeitschriftenartikel Sarma, Dominik; Mielke, Johannes; Sahre, Mario; Beck, Uwe; Hodoroaba, Vasile-Dan; Rurack, Knut TSEM-based contour analysis as a tool for the quantification of the profile roughness of silica shells on polystyrene core particles Core-shell (CS) particles with a polymeric core and a silica shell play an important role in the materials and (bio)analytical sciences. Besides the establishment of reliable synthesis procedures, comprehensive particle characterization is essential for batch-to-batch reproducibility and objective performance assessment across architectures, protocols, and laboratories. Particle characterization with respect to size, size distribution, shell thickness and texture, surface area and roughness or materials composition is commonly conducted with different analytical methods, often on different samples. Our approach uses a dual-mode TSEM/SEM set-up with an EDX detector to obtain a complementary data set with sufficient statistical confidence of one and the same sample on a single instrument. Our protocol reveals information about size, size distribution and shell thickness of the various particles employed from overview images, while an increased field of view (FOV) and high-resolution EDX analysis yields detailed information on shell texture and elemental composition. An image analysis tool was developed to derive and quantify the profile roughness of CS particles from individual beads. Comparison with surface roughness data from AFM showed a similar trend in roughness across the series of particles. Reliable classification into smooth and rough is proposed and roughness changes within different particle batches were tracked systematically. Amsterdam Elsevier B.V. 2017 Applied Surface Science 426 1 446 455 10.1016/j.apsusc.2017.07.099 2017-10-04 OPUS4-42257 Zeitschriftenartikel Gotor, Raul; Ashokkumar, Pichandi; Hecht, Mandy; Keil, Karin; Rurack, Knut Optical pH Sensor Covering the Range from pH 0−14 Compatible with Mobile-Device Readout and Based on a Set of Rationally Designed Indicator Dyes In this work, a family of pH-responsive fluorescent probes has been designed in a rational manner with the aid of quantum chemistry tools, covering the entire pH range from 0−14. Relying on the boron−dipyrromethene (BODIPY) core, all the probes as well as selected reference dyes display very similar spectroscopic properties with ON−OFF fluorescence switching responses, facilitating optical readout in simple devices used for detection and analysis. Embedding of the probes and reference dyes into hydrogel spots on a plastic strip yielded a test strip that reversibly indicates pH with a considerably small uncertainty of ~0.1 pH units. These strips are not only reusable but, combined with a 3D-printed case that can be attached to a smartphone, the USB port of which drives the integrated LED used for excitation, allows for autonomous operation in on-site or in-the-field applications; the developed Android application software ("app") further simplifies operation for unskilled users. Washington, D.C., USA American Chemical Society 2017 Analytical Chemistry 89 16 8437 8444 urn:nbn:de:kobv:b43-422571 10.1021/acs.analchem.7b01903 http://creativecommons.org/licenses/by-nc-nd/3.0/de/deed.de 2017-10-04 OPUS4-42258 Zeitschriftenartikel Wagner, Sabine; Bell, Jérémy; Biyikal, Mustafa; Gawlitza, Kornelia; Rurack, Knut Integrating fluorescent molecularly imprinted polymer (MIP) sensor particles with a modular microfluidic platform for nanomolar smallmolecule detection directly in aqueous samples Fluorescent sensory MIP (molecularly imprinted polymer) particles were combined with a droplet-based 3D microfluidic system for the selective determination of a prototype small-molecule analyte of environmental concern, 2,4-dichlorophenoxyacetic acid or 2,4-D, at nanomolar concentration directly in water samples. A tailor-made fluorescent indicator cross-linker was thus designed that translates the binding event directly into an enhanced fluorescence signal. The phenoxazinone-type cross-linker was co-polymerized into a thin MIP layer grafted from the surface of silica microparticles following a RAFT (reversible addition-fragmentation chain transfer) polymerization protocol. While the indicator cross-linker outperformed its corresponding monomer twin, establishment of a phase-transfer protocol was essential to guarantee that the hydrogen bond-mediated signalling mechanism between the urea binding site on the indicator cross-linker and the carboxylate group of the analyte was still operative upon real sample analysis. The latter was achieved by integration of the fluorescent core-shell MIP sensor particles into a modular microfluidic platform that allows for an in-line phasetransfer assay, extracting the analyte from aqueous sample droplets into the organic phase that contains the sensor particles. Real-time fluorescence determination of 2,4-D down to 20 nM was realized with the system and applied for the analysis of various surface water samples collected from different parts of the world. Amsterdam Elsevier B.V. 2018 Biosensors and Bioelectronics 99 1 244 250 10.1016/j.bios.2017.07.053 2017-10-04 OPUS4-42260 Vortrag Rurack, Knut On the Integration of Fluorescent Probes with Molecularly Imprinted Polymers for Powerful Sensor Materials Molecularly imprinted polymers (MIPs) are an established and powerful matrix for the selective enrichment and separation of chemical species, especially of small organic molecules. Because MIPs contain cavities in their matrix that are complementary in size, shape and electronic/electrostatic or hydrogen bonding demand to the imprinted target molecule or template, they are frequently termed "artificial antibodies". Compared to natural antibodies, they are chemically and physically much more robust. MIP formation proceeds through the polymerization of a mixture of functional monomers and cross-linkers in the presence of the template with subsequent extraction of the latter. While this strategy has been successfully employed for separation MIPs since decades, the development of sensory MIPs has long been limited to the combination of a MIP as enrichment phase with a separate signalling element in a discontinuous fashion, being unsuitable for many sensing applications. Only very recently, the implementation of specifically designed fluorescent probes into MIPs has been successfully accomplished, fluorescence being one of the most versatile, sensitive and easily miniaturizable techniques. This presentation will introduce basic design considerations, challenges, limitations and the potential that lies with such sensor materials on the background of the work carried out in our group. 2017 Bioinspired Materials 2017 Manchester, UK 31.08.2017 01.09.2017 2017-10-04 OPUS4-45912 Zeitschriftenartikel Bell, Jérémy; Gawlitza, Kornelia; Rurack, Knut Mit Tröpfchen Spielen Mikrofluidische Systeme sind leistungsstarke analytische Tools mit attraktiven Eigenschaften wie miniaturisierter Größe, geringem Reagenzien und Probenverbrauch, schneller Ansprech- und kurzer Messzeit. Der Bedarf solcher leistungsstarken, miniaturisierten und direkt vor Ort anwendbaren Sensorsysteme steigt kontinuierlich, hauptsächlich durch das Bedürfnis der Gesellschaft, schneller, besser und umfassender über kritische Faktoren im Lebens- und Arbeitsumfeld sowie der Umwelt informiert zu sein. Weinheim, Deutschland Wiley-VCH Verlag GmbH & Co. KGaA 2018 GIT Labor-Fachzeitschrift 8 8 2 4 urn:nbn:de:kobv:b43-459120 http://www.gesetze-im-internet.de/urhg/index.html 2018-09-12 OPUS4-45913 Zeitschriftenartikel Bell, Jérémy; Gawlitza, Kornelia; Rurack, Knut Playing with Droplets Microfluidic devices are powerful analytical tools with appealing features such as miniaturized size, low reagent and sample consumption, rapid response and short measurement times. As society wants to be ever better, earlier and more comprehensively informed about critical factors in life, work, and the environment, the demand for powerful measurement devices for use outside of the laboratory constantly increases. Weinheim, Deutschland Wiley-VCH Verlag GmbH & Co. KGaA 2018 GIT Laboratory Journal 4 2 4 urn:nbn:de:kobv:b43-459131 http://www.gesetze-im-internet.de/urhg/index.html 2018-09-12 OPUS4-46013 Zeitschriftenartikel Climent Terol, Estela; Hecht, Mandy; Witthuhn, Heike; Gawlitza, Kornelia; Rurack, Knut Mix-&-read determination of Mercury(II) at trace levels with hybrid mesoporous silica materials incorporating fluorescent probes by a simple mix-&-load technique The synthesis, characterization, and application of mesoporous materials containing boron-dipyrromethene (BODIPY) moieties that allow the sensitive and selective detection of HgII in aqueous environments by fluorescence enhancement is reported. For this purpose, BODIPY dye I containing a thia-aza crown ether receptor as the fluorescent probe for the detection of HgII in aqueous environments is encapsulated into mesoporous materials to avoid self-quenching or aggregation in water. Determination of HgII is accomplished within a few seconds with high selectivity and sensitivity, reaching a limit of detection of 12 ppt. The determination of trace amounts of HgII in natural waters and in fish extracts is demonstrated by using our sensing material. The incorporation of the material into several μ-PAD strips yields a portable, cheap, quick, and easy-to-handle tool for trace HgII analysis in water. Weinheim Wiley-VCH 2018 ChemistryOpen 7 12 957 968 urn:nbn:de:kobv:b43-460138 10.1002/open.201800277 https://creativecommons.org/licenses/by-nc-nd/4.0/deed.de 2018-09-21 OPUS4-46888 Zeitschriftenartikel Abdelshafi, Nahla A.; Bell, Jérémy; Rurack, Knut; Schneider, Rudolf Microfluidic electrochemical immunosensor for the trace analysis of cocaine in water and body fluids Quick but accurate testing and on-the-spot monitoring of cocaine in oral fluids and urine continues to be an important toxicological issue. In terms of drug testing, a number of devices have been introduced into the market in recent decades, notably for workplace inspection or roadside testing. However, these systems do not always fulfill the requirements in terms of reliability, especially when low cut-off levels are required. With respect to surface water, the presence of anthropogenic small organic molecules such as prescription and over-the-counter pharmaceuticals as well as illicit drugs like cannabinoids, heroin, or cocaine, has become a challenge for scientists to develop new analytical tools for screening and on-site analysis because many of them serve as markers for anthropogenic input and consumer behavior. Here, a modular approach for the detection of cocaine is presented, integrating an electrochemical enzyme-linked immunosorbent assay (ELISA) performed on antibody-grafted magnetic beads in a hybrid microfluidic sensor utilizing flexible tubing, static chip and screen-printed electrode (SPE) elements for incubation, recognition, and cyclic voltammetry measurements. A linear response of the sensor vs. the logarithm of cocaine concentration was obtained with a limit of detection of 0.15 ng/L. Within an overall assay time of 25 minutes, concentrations down to 1 ng/L could be reliably determined in water, oral fluids, and urine, the system possessing a dynamic working range up to 1 mg/L. Hoboken, New Jersey, USA Wiley-VCH 2018 Drug Testing and Analysis 11 3 492 500 10.1002/dta.2515 2018-12-12 OPUS4-47923 Zeitschriftenartikel Gotor, Raúl; Bell, Jérémy; Rurack, Knut Tailored fluorescent solvatochromic test strips for quantitative on-site detection of gasoline fuel adulteration Gasoline adulteration is a frequent problem world-wide, because of the chance of quick, maximized profits. However, addition of cheaper ethanol or hydrocarbons like kerosene does not only result in economic damage but also poses problems for vehicles and the environment. To enable law enforcement forces, customers or enterprises to uncover such a fraudulent activity directly upon suspicion and without the need to organize for sampling and laboratory analysis, we developed a simple strip-based chemical test. Key to the favorable performance was the dedicated materials tailoring, which led to test strips that consisted of a cellulose support coated with silica, passivated with hexamethyldisilazane and functionalized covalently with a molecular probe. The probe fluoresces brightly across a broad solvent polarity range, enabling reliable quantitative measurements and data analysis with a conventional smartphone. The assays showed high reproducibility and accuracy, allowing not only for the detection of gasoline adulteration but also for the on-site monitoring of the quality of commercial E10 gasoline. London, UK Royal Society of Chemistry 2019 Journal of Materials Chemistry C 7 8 2250 2256 urn:nbn:de:kobv:b43-479231 10.1039/C8TC04818E https://creativecommons.org/licenses/by-nc/4.0/deed.de 2019-05-06 OPUS4-58808 Zeitschriftenartikel Kislenko, Evgeniia; Incel, A.; Gawlitza, Kornelia; Sellergren, B.; Rurack, Knut Towards molecularly imprinted polymers that respond to and capture phosphorylated tyrosine epitopes using fluorescent bis-urea and bis-imidazolium receptors Early detection of cancer is essential for successful treatment and improvement in patient prognosis. Deregulation of post-translational modifications (PTMs) of proteins, especially phosphorylation, is present in many types of cancer. Therefore, the development of materials for the rapid sensing of low abundant phosphorylated peptides in biological samples can be of great therapeutic value. In this work, we have synthesised fluorescent molecularly imprinted polymers (fMIPs) for the detection of the phosphorylated tyrosine epitope of ZAP70, a cancer biomarker. The polymers were grafted as nanometer-thin shells from functionalised submicron-sized silica particles using a reversible addition-fragmentation chain-transfer (RAFT) polymerisation. Employing the combination of fluorescent urea and intrinsically cationic bis-imidazolium receptor cross-linkers, we have developed fluorescent sensory particles, showing an imprinting factor (IF) of 5.0. The imprinted polymer can successfully distinguish between phosphorylated and non-phosphorylated tripeptides, reaching lower micromolar sensitivity in organic solvents and specifically capture unprotected peptide complements in a neutral buffer. Additionally, we have shown the importance of assessing the influence of counterions present in the MIP system on the imprinting process and final material performance. The potential drawbacks of using epitopes with protective groups, which can co-imprint with targeted functionality, are also discussed. Cambridge Royal Society of Chemistry 2023 Journal of Materials Chemistry B 1 10 urn:nbn:de:kobv:b43-588089 10.1039/d3tb01474f https://creativecommons.org/licenses/by/4.0/deed.de 2023-11-15 OPUS4-58815 Vortrag Rurack, Knut Development of a Lab-on-a-Chip for the Detection of Nerve Agents with a Handheld Device The development of a Lab-on-a-Chip (LoC) is presented, which can detect reactive phosphorous compounds in the gas phase in combination with an optochemical hand-held sensor. The LoC prototype contains three pairs of sensing materials containing fluorescent indicator dyes in various carrier materials. By measuring the fluorescence response to phosphoryl chloride, a surrogate compound, the detection of chemical warfare agents (CWAs) in gas phase becomes possible within seconds, introducing a novel approach to CWA detection. 2023 IEEE Sensors Conference Vienna, Austria 29.10.2023 01.11.2023 2023-11-14 OPUS4-58816 Vortrag Rurack, Knut Empowering test strips for rapid, highly sensitive and multiplexed analysis of small molecule analytes at a point-of-need In particular, the rapid development of lateral flow assays as indispensable tools for everyone to contain the SARS-CoV-2 pandemic has fuelled the global demand for analytical tests that can be used outside dedicated laboratories. In addition to their use in medical diagnostics, rapid tests and assays have become increasingly important in various fields such as food safety, security, forensics, and environmental management. The advantage is obvious: taking the assay directly to the sample minimizes the time between suspicion and decision-making, allowing faster action. Especially today, when mobile communication devices with powerful computing capabilities and built-in cameras are ubiquitous, more people than ever before around the world have the basic skills to operate a powerful detector at their fingertips. This sets the stage for a much wider use of analytical measurements in terms of prognosis and prevention, enabling professional laypersons in particular. However, current strip-based systems are primarily focused on single parameter analysis, whether it is SARS-CoV-2 biomarkers, blood glucose levels, or lead concentrations in water samples. Industrial applications of such methods also often still rely on single-parameter assays, requiring multiple runs even for a limited number of key parameters. Overcoming these limitations depends on developing low-number multiplexing strategies that ensure robustness, reliability, speed, ease of use, and sensitivity. This lecture will give an overview of several generic approaches developed in recent years to address these challenges. It will highlight how the synergy of supramolecular (bio)chemistry, luminescence detection, hybrid (nano)materials and device miniaturization can result in powerful (bio)analytical assays that can be used at a point-of-need.1-5 Selected examples will introduce key aspects of such systems that include tailored signaling mechanisms and recognition elements, materials functionalization and device integration, including hybrid nanomaterials, gated indicator release systems, strip modification, and smartphone-based analysis. 2023 15th Rapid Methods Europe Conference Amsterdam, Netherlands 06.11.2023 08.11.2023 2023-11-14 OPUS4-56735 Zeitschriftenartikel Kubheka, G.; Climent, Estela; Tobias, Charlie; Rurack, Knut; Mack, J.; Nyokong, T. Multiplexed Detection of Human Papillomavirus Based on AzaBODIPY-Doped Silica-Coated Polystyrene Microparticles Human papillomavirus (HPV) DNA detection can enable the early diagnosis of high-risk HPV types responsible for cervical cancer. HPV detection is also essential for investigating the clinical behavior and epidemiology of particular HPV types, characterization of study populations in HPV vaccination trials and monitoring the efficacy of HPV vaccines. In this study, two azaBODIPY dyes (1 and 2) were used as references and were doped into polystyrene particles (PS40), while a short HPV DNA single strand was used as a target molecule and was covalently bound to the silica shell. These particles were employed as optical probes in 1:1 hybridization assays, and their potential applicability as a tool for multiplex assays for the detection of different strands of HPV was evaluated using flow cytometry. A good separation in the fluorescence of the four different voncentrations prepared for each dye was observed. To perform the hybridization assays, HPV18, HPV16, HPV11 and HPV6 single strands were attached to the particles through EDC-mediated coupling. The c-DNA-1-PS40 and c-DNA-2-PS40 particles exhibited low limit of detection (LOD) and quantification (LOQ) values for HPV11, and a narrow detection range was obtained. Multiplexed assay experiments were successfully performed for both particles, and the results proved that c-DNA-1-PS40 could potentially be used as a tool for multiplexing assays and merits further in-depth study in this context. Basel MDPI 2023 Chemosensors 11 1 1 21 urn:nbn:de:kobv:b43-567358 10.3390/chemosensors11010001 https://creativecommons.org/licenses/by/4.0/deed.de 2022-12-29 OPUS4-56920 Zeitschriftenartikel Burnage, Samual; Bell, Jérémy; Wan, Wei; Kislenko, Evgeniia; Rurack, Knut Combining a hybrid chip and tube microfluidic system with fluorescent molecularly imprinted polymer (MIP) core-shell particles for the derivatisation, extraction, and detection of peptides with N-terminating phosphorylated tyrosine The reliable identification and quantitation of phosphorylated amino acids, peptides and proteins is one of the key challenges in contemporary bioanalytical research, an area of particular interest when attempting to diagnose and treat diseases at an early stage. We have developed a synthetic probe for targeting phosphorylated amino acids, based on core-shell submicron-sized particles consisting of a silica core, coated with a molecularly imprinted polymer (MIP) shell. The MIP layer contains a fluorescent probe crosslinker which binds selectively to phosphorylated tyrosine (pY) moieties with a significant imprinting factor (IF) and responds with a "light-up" fluorescence signal. The bead-based ratiometric detection scheme has been successfully transferred to a microfluidic chip format and its applicability to rapid assays has been exemplarily shown by discriminating a pY-terminating oligopeptide against its nonphosphorylated counterpart. Such miniaturised devices could lead to an automated pY or pY N-terminated peptide measurement system in the future. The setup combines a modular microfluidic system for amino acid derivatisation, extraction (by micropillar co-flow) and selective adsorption and detection with the fluorescent MIP core-shell particle probes. A miniaturised optical assembly for low-light fluorescence measurements was also developed, based on miniaturised opto-electronic parts and optical fibres. The emission from the MIP particles upon binding of pY or pY N-terminated peptides could be monitored in real-time. Cambridge Royal Society of Chemistry 2022 Lab on a Chip 23 3 466 474 urn:nbn:de:kobv:b43-569204 10.1039/d2lc00955b https://creativecommons.org/licenses/by/4.0/deed.de 2023-01-30 OPUS4-57892 Zeitschriftenartikel Mansurova, Maria; Gotor, Raúl; Johann, Sergej; Neumann, Patrick P.; Bartholmai, Matthias; Rurack, Knut; Bell, Jérémy Fluorescent Hydrophobic Test Strips with Sterically Integrated Molecular Rotors for the Detection of Hydrocarbons in Water and Soil with an Embedded Optical Read-Out Contamination of natural bodies of water or soil with oils and lubricants (or generally, hydrocarbon derivatives such as petrol, fuels, and others) is a commonly found phenomenon around the world due to the extensive production, transfer, and use of fossil fuels. In this work, we develop a simple system for the on-field detection of total petroleum hydrocarbons (TPHs) in water and soil. The test is based on the measurement of the fluorescence signal emitted by the molecular rotor 2-[ethyl[4-[2-(4-nitrophenyl)ethenyl]phenyl]amino]ethanol (4-DNS-OH). This dye is embedded in a hydrophobic polymeric matrix (polyvinylidene fluoride), avoiding interactions with water and providing a robust support for use in a test strip fashion. Together with the strips, an embedded optical system was designed for fluorescence signal read-out, featuring a Bluetooth low-energy connection to a commercial tablet device for data processing and analysis. This system works for the detection and quantification of TPHs in water and soil through a simple extraction protocol using a cycloalkane solvent with a limit of detection of 6 ppm. Assays in surface and sea waters were conclusive, proving the feasibility of the method for in-the-field operation. Washington, United States American Chemical Society 2023 Energy and Fuels 1 6 10.1021/acs.energyfuels.3c01175 2023-07-12 OPUS4-58533 Vortrag Rurack, Knut PFAS Sensors This contribution provides an introduction to the development of sensors for PFAS analysis, presents the most common approaches, and describes the opto-microfluidic strategy in combination with polymerizable indicators and detection matrices currently being pursued by the Chemical and Optical Sensing Division at BAM. 2023 Advancements of Analytical Techniques for Per- and Polyfluoroalkyl Substances (PFAS) – Second Workshop 2023 Berlin, Germany 19.09.2023 19.09.2023 2023-10-11 OPUS4-58534 Zeitschriftenartikel Muguruza, A.R.; Odyniec, M.L.; Manhota, M.; Habib, Z.; Rurack, Knut; Blair, J.M.A.; Kuehne, S.A.; Walmsley, A.D.; Pikramenou, Z. Antibiotic entrapment in antibacterial micelles as a novel strategy for the delivery of challenging antibiotics from silica nanoparticles Silica materials are popular in biomedical applications as composites and drug delivery platforms due to their low toxicity and biocompatibility. Mesoporous silica nanoparticles are attractive drug delivery systems based on their porous silica framework with high surface area. In the preparation of mesoporous silica frameworks, most commonly, MCM-41, the efficient removal of the template responsible for introducing porous networks, cetyltrimethyl ammonium bromide (CTAB), is a critical step due to the template's high toxicity in the environment and human health. In this work, we present a new one-pot approach of introducing challenging antibiotics within a silica framework without the need of toxic templates, but instead using micelle formation by an antibacterial agent. We demonstrate that micelles formed by cetylpyridinium chloride (CPC), a known antibacterial agent, entrap antibiotics such as rifampicin and ciprofloxacin. Extensive NMR studies elucidate the precise localisation of the antibiotic within the CPC micelle. Ciprofloxacin is placed between the outer and palisade region while rifampicin is located further into the hydrophobic CPC micelle core. In both cases, the formation of the silica framework can be built around the CPC-antibiotic loaded micelles. The resulting silica nanoparticles show loading of both CPC and antibiotic agents, porosity and dual antibacterial release upon disruption of the micelle within the silica framework. The design not only provides a strategy of a therapeutic design to form porous frameworks but also highlights the potential of precise antibiotic dose and release in nanoparticle systems. Amsterdam Elsevier Inc. 2024 Microporous and Mesoporous Materials 363 1 11 10.1016/j.micromeso.2023.112841 2023-10-11 OPUS4-58526 Vortrag Bell, Jérémy; Climent, Estela; Gotor, Raúl; Tobias, Charlie; Martin-Sanchez, Pedro M.; Rurack, Knut Dipstick coated with polystyrene-silica core-shell particles for the detection of microbiological fuel contamination Microbial contamination of fuels by fungi or bacteria poses risks such as corrosion and fuel system fouling, which can lead to critical problems in refineries and distribution systems and has a significant economic impact at every stage of the process. Many factors have been cited as being responsible for microbial growth, like the presence of water in the storage tanks. In fact, only 1 % water in a storage system is sufficient for the growth of microorganisms like bacteria or yeasts, as well as for the development of fungal biomass at the oil/water interface. This work presents a rapid test for the accurate determination of genomic DNA from aqueous fuel extracts. The detection is based on the use of polystyrene-mesoporous silica core-shell particles onto which modified fluorescent molecular beacons are covalently grafted. These beacons contain in the hairpin loop a target sequence highly conserved in all bacteria, corresponding to a fragment of the 16S ribosomal RNA subunit. The designed single-stranded molecular beacon contained fluorescein as an internal indicator and a quencher in its proximity when not hybridized. Upon hybridization in presence of the target sequence, the indicator and the quencher are spatially separated, resulting in fluorescence enhancement. To perform the assay the developed particles were deposited on different glass fibre strips to obtain a portable and sensitive rapid test. The assays showed that the presence of genomic DNA extracts from bacteria down to 50-70 μg L-1 induced a fluorescence response. The optical read-out was adapted for on-site monitoring by fitting a 3D-printed case to a conventional smartphone, taking advantages of the sensitivity of the CMOS detector. Such embedded assembly enabled the detection of genomic DNA in aqueous extracts down to the mg L-1 range and represents an interesting step toward on-site monitoring of fuel contamination. 2023 IMA 2023 Chania, Greece 18.09.2023 2023-10-10 OPUS4-58527 Vortrag Sun, Yijuan; Pérez-Padilla, Víctor; Valderrey, Virginia; Bell, Jérémy; Gawlitza, Kornelia; Rurack, Knut Fluorescence Detection of Perfluoroalkyl Carboxylic Acids with a Miniaturised Assay Per- and polyfluoroalkyl substances (PFAS) are a class of man-made organo-fluorine chemicals that have become environmental contaminants of emerging concern, originating from a variety of materials such as adhesive, stain- and oil-resistant coatings, firefighting foams, etc. The high strength of this C-F bond makes PFAS thermodynamically stable and resistant to (bio)degradation, thus retaining them in the environment over time. Perfluoroalkyl carboxylic acids (PFCAs), one category of the most used PFAS, consist of a fully fluorinated carbon backbone and a charged carboxylic acid headgroup, and have been classified as Substances of Very High Concern (SVHC) and added to the REACH Candidate List due to their persistence in the environment, non-biodegradability and toxicological effects.[1-2] Traditional techniques for the analysis of PFCAs include GC-MS, HRMS and HPLC-based approaches, which are laborious, not portable, costly and require trained personnel. In contrast, fluorescence assays can be designed as easy-to-operate, portable and cost-effective methods with high sensitivity and fast response. Integration of fluorescent probes with an adequately miniaturized assay enables a promising alternative for PFCAs analysis. Here, a novel guanidine fluorescent probe has been synthesized and fully characterized for the detection of PFCAs in a biphasic extract-&-detect assay. The fluorescent probe was then incorporated into polymeric matrices supported by a red dye-doped SiO2 nanoparticle to construct a dual-emission sensing platform. Such a system allows precise and selective detection of PFCAs, reducing the interference of competitors, matrix effects and other factors except for the PFCAs. The system was then employed in a droplet-based microfluidic setup which offers a portable and easy to operate detection platform. 2023 IMA 2023 Chania, Greece 18.09.2023 2023-10-10 OPUS4-57384 Zeitschriftenartikel Sjöberg, T.; El-Schich, Z.; Rurack, Knut; Gjörloff Wingren, A. Colorectal Cancer Cell Spheroids Co-Cultured with Molecularly Imprinted Fluorescent Particles Targeting Sialic Acid Show Preserved Cell Viability In vitro cultured 3D models of CRC have been demonstrated to hold considerable worth in drug discovery, drug resistance analysis, and in studying cell-cell and cell-matrix interactions that occur in the tumor microenvironment. The 3D models resemble the in vivo physiological microenvironment by replicating the cell type composition and tissue architecture. Molecularly imprinted polymers (MIPs) have been investigated for use instead of antibodies against small nonimmunogenic structures, such as sialic acid (SA). Glyco-conjugates including SA are present on all cells, and often deregulated on cancer cells. Here, we present a novel approach for targeting and detecting colorectal cancer cells (CRC) by using in vitro cultured HT29 3D spheroids co-cultured in vitro with either fluorescent MIPs targeting SA, SA-MIPs, or the two lectins targeting SA, MAL I, and SNA. Both formaldehyde-fixed and viable HT29 3D spheroids with or without SA-MIPs were imaged in 3D by confocal microscopy. The results revealed a preserved cell morphology and viability of the HT29 3D spheroids co-cultured in vitro with SA-MIPs. However, the lectins MAL I and SNA targeting the alpha-2,3 or alpha-2,6 SA glycosidic linkages, respectively, affected the cell viability when co-cultured with the viable HT29 3D spheroids, and no living cells could be detected. Here, we have shown that the SA-MIPs could be used as a safe and low-cost diagnostic tool for targeting and detecting cancer cells in a physiologically relevant 3D cancer model in vitro. Basel MDPI 2023 Applied Sciences 13 9 1 6 urn:nbn:de:kobv:b43-573840 10.3390/app13095330 https://creativecommons.org/licenses/by/4.0/deed.de 2023-04-27 OPUS4-59367 Beitrag zu einem Tagungsband Biyikal, Mustafa; Rurack, Knut Development of a Lab-on-a-Chip for the Detection of Nerve Agents with a Handheld Device The development of a Lab-on-a-Chip (LoC) is presented, which can detect reactive phosphorous compounds in the gas phase in combination with an optochemical hand-held sensor. The LoC prototype contains three pairs of sensing materials containing fluorescent indicator dyes in various carrier materials. By measuring the fluorescence response to phosphoryl chloride, a surrogate compound, the detection of chemical warfare agents (CWAs) in gas phase becomes possible within seconds, introducing a novel approach to CWA detection. New York IEEE 2023 Proceedings 2023 IEEE Sensors 979-8-3503-0387-2 2023 IEEE SENSORS Conference Vienna, Austria 29.10.2023 01.11.2023 1 4 10.1109/SENSORS56945.2023.10325263 2024-01-22 OPUS4-59453 Zeitschriftenartikel Zhang, Kun; Carrod, Andrew J.; Del Giorgio, Elena; Hughes, Joseph; Rurack, Knut; Bennet, Francesca; Hodoroaba, Vasile-Dan; Harrad, Stuart; Pikramenou, Zoe Luminescence Lifetime-Based Sensing Platform Based on Cyclometalated Iridium(III) Complexes for the Detection of Perfluorooctanoic Acid in Aqueous Samples Luminescence lifetimes are an attractive analytical method for detection due to its high sensitivity and stability. Iridium probes exhibit luminescence with long excited-state lifetimes, which are sensitive to the local environment. Perfluorooctanoic acid (PFOA) is listed as a chemical of high concern regarding its toxicity and is classified as a "forever chemical". In addition to strict limits on the presence of PFOA in drinking water, environmental contamination from industrial effluent or chemical spills requires rapid, simple, accurate, and cost-effective analysis in order to aid containment. Herein, we report the fabrication and function of a novel and facile luminescence sensor for PFOA based on iridium modified on gold surfaces. These surfaces were modified with lipophilic iridium complexes bearing alkyl chains, namely, IrC6 and IrC12, and Zonyl-FSA surfactant. Upon addition of PFOA, the modified surfaces IrC6-FSA@Au and IrC12-FSA @Au show the largest change in the red luminescence signal with changes in the luminescence lifetime that allow monitoring of PFOA concentrations in aqueous solutions. The platform was tested for the measurement of PFOA in aqueous samples spiked with known concentrations of PFOA and demonstrated the capacity to determine PFOA at concentrations >100 μg/L (240 nM). American Chemical Society (ACS) 2024 Analytical Chemistry 96 4 1565 1575 urn:nbn:de:kobv:b43-594535 10.1021/acs.analchem.3c04289 https://creativecommons.org/licenses/by/4.0/deed.de 2024-01-31 OPUS4-59544 Zeitschriftenartikel Mansurova, Maria; Johann, Sergej; Kohlhoff, Harald; Rurack, Knut; Bartholmai, Matthias; Bell, Jérémy On-Site Analytical Tool Based on Crude Oil Fluorescence and Chemometrics for the Rapid Determination of the Nature and Essential Properties of Oil Spills With the reduction of large oil spills because of stricter regulations and safety measures, the question of how to manage smaller oil spills arises. Few on-site analytical tools are available for first responders or other law enforcement personnel to rapidly test for crude oil in the early management of localized polluted areas. The approach reported here relies on well-described computer-assisted multivariate data analysis of the intrinsic fluorescence fingerprints of crude oils to build a multivariate model for the rapid classification of crude oils and the prediction of their properties. Thanks to a dedicated robust portable reader, the method allowed classification and accurate prediction of various properties of crude oil samples like density (according to API, the American Petroleum Institute and viscosity as well as composition parameters such as volume fractions of paraffins or aromatics. In this way, autonomous operation in on-site or in-the-field applications becomes possible based on the direct (undiluted and untreated) measurement of samples and a rapid, tablet-operated readout system to yield a robust and simple analytical test with superior performance. Testing in real-life scenarios allowed the successful classification and prediction of a number of oil spill samples as well as weathered samples that closely resemble samples collected by first responders. American Chemical Society (ACS) 2024 ACS ES&T Water 4 2 621 627 urn:nbn:de:kobv:b43-595442 10.1021/acsestwater.3c00648 https://creativecommons.org/licenses/by/4.0/deed.de 2024-02-22