TY - JOUR A1 - Rurack, Knut A1 - Resch-Genger, Ute A1 - Bricks, J.L. A1 - Spieles, Monika T1 - Cation-triggered 'switching on' of the red/near infra-red (NIR) fluorescence of rigid fluorophore-spacer-receptor ionophores PY - 2000 DO - https://doi.org/10.1039/b006430k SN - 0022-4936 SN - 0009-241x SN - 1359-7345 SN - 1364-548x IS - 21 SP - 2103 EP - 2104 PB - Royal Society of Chemistry CY - Cambridge AN - OPUS4-2087 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rurack, Knut A1 - Hoffmann, Katrin A1 - Al-Soufi, W. A1 - Resch-Genger, Ute T1 - 2,2'-Bipyridyl-3,3'-diol Incorporated into AlPO4-5 Crystals and Its Spectroscopic Properties as Related to Aqueous Liquid Media N2 - A novel fluorescent host-guest material, molecular sieves of AlPO4-5-type doped with 2,2'-bipyridyl-3,3'-diol, was prepared and spectroscopically characterized. The composite crystals show a pronounced optical anisotropy, indicating a high degree of alignment of the guest molecules within the zeolitic pore system. A mean tilting angle of 22 was found for the orientation of the individual dye molecules in the straight channels. The corrected fluorescence emission spectra were determined, and time-resolved fluorescence studies revealed that the dye molecules are preferentially found in three different types of microenvironment. By invoking pH-dependent studies of the dye in aqueous solution, we could trace these spectroscopic features back to two main influences, coadsorbed water within AlPO4-5 pores and guest-host interactions with a few relatively weak Brnsted acid (defect) sites of the inorganic host network. PY - 2002 DO - https://doi.org/10.1021/jp0259622 SN - 1520-6106 SN - 1520-5207 SN - 1089-5647 VL - 106 IS - 38 SP - 9744 EP - 9752 PB - Soc. CY - Washington, DC AN - OPUS4-1546 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rurack, Knut A1 - Resch-Genger, Ute A1 - Senoner, Mathias A1 - Dähne, Siegfried T1 - A new fluorescence probe for trace metal ions: cation dependent spectroscopic properties KW - 2,2´-Bipyridyl-3,3´-diol KW - Metal ions KW - Cation dependence KW - Fluorescence probe PY - 1993 SN - 1053-0509 SN - 1573-4994 VL - 3 IS - 3 SP - 141 EP - 143 PB - Plenum Publ. Corp. CY - New York, NY AN - OPUS4-2105 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rurack, Knut A1 - Resch-Genger, Ute T1 - Rigidization, preorientation and electronic decoupling-the "magic triangle" for the design of highly efficient fluorescent sensors and switches N2 - One of the key interests in the recent development of fluorescent molecular sensors and switches is the realization of systems that show strong signal changes as a response to the chemical trigger. Aiming at rational probe design, this article compiles and compares different promising strategies to extract those supramolecular and photophysical features that allow the construction of molecular devices suitable for efficient signaling. The examples comprise fluorescence OFF–ON as well as ON–OFF operative systems and the mechanisms, properties, and limitations of the different design concepts are discussed. PY - 2002 DO - https://doi.org/10.1039/b100604p SN - 0306-0012 SN - 1460-4744 VL - 31 IS - 2 SP - 116 EP - 127 PB - Royal Society of Chemistry CY - London AN - OPUS4-2083 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Resch-Genger, Ute A1 - Rurack, Knut A1 - Senoner, Mathias T1 - Zeitaufgelöste Fluorometrie in der Wasseranalytik PY - 1994 SN - 0341-5163 SN - 1521-3854 VL - 42 IS - 5 SP - 504 EP - 506 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-2104 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bricks, J. L. A1 - Slominskii, J. L. A1 - Kudinova, M. A. A1 - Tolmachev, A. I. A1 - Rurack, Knut A1 - Resch-Genger, Ute A1 - Rettig, W. T1 - Syntheses and photophysical properties of a series of cation-sensitive polymethine and styryl dyes N2 - The syntheses and photophysical properties of 20 cation-sensitive fluoroionophores carrying the tetraoxa monoaza 15-crown-5 receptor are described and discussed. Whereas complexation induces only weak effects for the positively charged hemicyanine probes, the closely related styryl dyes show stronger changes in their photophysical properties upon cation binding in the analytically advantageous near-infrared (NIR) region. The strongest effects in both cation-induced spectral effects and complex stability constants are observed for the uncharged probes of styryl base-type, but these probes usually absorb and emit at shorter wavelengths in the UV/VIS region. For both styryl dyes and styryl bases, in some cases cation-induced fluorescence enhancement or quenching is found. KW - Fluorescence KW - Ionophores KW - Unsymmetrical cyanines KW - Styryl dyes KW - Styryl bases PY - 2000 DO - https://doi.org/10.1016/S1010-6030(00)00208-2 SN - 1010-6030 SN - 1873-2666 VL - 132 IS - 3 SP - 193 EP - 208 PB - Elsevier CY - Lausanne AN - OPUS4-2089 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rurack, Knut A1 - Unger, Brita A1 - Müller, Ralf A1 - Jancke, Harald A1 - Resch-Genger, Ute T1 - Die Strukturentwicklung von SiO2 Solen und Gelen im Vergleich mikroskopischer und makroskopischer Untersuchungsmethoden T2 - 77. Glastechnische Tagung CY - Leipzig, Deutschland DA - 2003-05-26 PY - 2003 VL - 77 SP - 101 EP - 104 PB - DGG CY - Offenbach AN - OPUS4-3121 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Köster, D. A1 - Mayer-Enthart, Elke A1 - Sialelli, J. A1 - Rurack, Knut A1 - Resch-Genger, Ute A1 - Seitz, H. T1 - Hula Hoop für DNA - Eine hoch sensitive Detektionsmethode für DNA Microarrays N2 - 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. KW - Newsletter von GABI KW - NGFN KW - GenoMik und FUGATO mit Informationen aus der deutschen Genomforschung PY - 2008 SN - 1617-562X VL - 1 SP - 23 EP - 25 PB - DHGP CY - Berlin AN - OPUS4-17393 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rurack, Knut A1 - Dekhtyar, M. A1 - Bricks, J. A1 - Resch-Genger, Ute A1 - Rettig, W. T1 - Quantum yield switching of fluorescence by selectively bridging single and double bonds in chalcones - involvement of two different types of conical intersections N2 - From the fluorescence properties of chalcones as a function of solvent polarity, and by the comparison to derivatives with donors and acceptors and with various selectively bridged bonds, it can be concluded that two emissive and two nonemissive states are needed to describe the fluorescence behavior. Three of these states are connected with bond twisting and lead to species with high or low dipole moment, two of them situated in the proximity of a conical intersection. KW - Fluoreszenz KW - Konische Durchschneidung PY - 1999 DO - https://doi.org/10.1021/jp992878m SN - 1089-5639 SN - 1520-5215 VL - 103 IS - 48 SP - 9626 EP - 9635 PB - Soc. CY - Washington, DC AN - OPUS4-2093 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rurack, Knut A1 - Rettig, W. A1 - Resch-Genger, Ute T1 - Unusually high cation-induced fluorescence enhancement of a structurally simple intrinsic fluoroionophore with a donor-acceptor-donor constitution N2 - Upon cation complexation, donor–acceptor–donor–substituted intrinsic fluoroionophore 3 shows red-shifted emission spectra accompanied by an extraordinarily high fluorescence enhancement. KW - Fluoreszenz KW - Ionophor KW - Ladungstransfer PY - 2000 DO - https://doi.org/10.1039/a909899b SN - 0022-4936 SN - 0009-241x SN - 1359-7345 SN - 1364-548x VL - 2000 IS - 5 SP - 407 EP - 408 PB - Royal Society of Chemistry CY - Cambridge AN - OPUS4-2091 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rurack, Knut T1 - Die Strukturentwicklung von SiO2 Solen und Gelen im Vergleich mikroskopischer und makroskopischer Untersuchungsmethoden T2 - 77. Glastechnische Tagung CY - Leipzig, Germany DA - 2003-05-26 PY - 2003 AN - OPUS4-3754 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Unger, Brita A1 - Rurack, Knut A1 - Müller, Ralf A1 - Resch-Genger, Ute A1 - Buttke, K. T1 - Effects of the Sol-Gel Processing on the Fluorescence Properties of Laser Dyes in Tetraethoxysilane Derived Matrices N2 - 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. KW - Sol-gel KW - Precursor chemistry KW - Fluorescence properties KW - Optical solids PY - 2000 DO - https://doi.org/10.1023/A:1008768318418 SN - 0928-0707 SN - 1573-4846 VL - 19 SP - 799 EP - 802 PB - Kluwer Academic Publ. CY - Dordrecht AN - OPUS4-1080 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Resch-Genger, Ute A1 - Rurack, Knut A1 - Bricks, J.L. A1 - Slominskii, J.L. T1 - New fluorophore receptor systems for heavy metal ions: a spectroscopic study KW - Fluorescence KW - Probe KW - Cation complex KW - Ion responsive KW - Chelation enhanced PY - 1997 SN - 1053-0509 SN - 1573-4994 VL - 7 IS - 1 SP - 231S EP - 233S PB - Plenum Publ. Corp. CY - New York, NY AN - OPUS4-2100 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Rurack, Knut A1 - Bricks, J. L. A1 - Slominskii, J. L. A1 - Resch-Genger, Ute ED - Dähne, S. T1 - Long wavelength emitting fluorescence probes for metal ions T2 - NATO Advanced Research Workshop on Syntheses, Optical Properties and Applications of Near-Infrared (NIR) Dyes in High Technology Fields CY - Trest', Czech Republic DA - 1997-09-24 PY - 1998 IS - 52 SP - 191 EP - 200 PB - Kluwer CY - Dordrecht AN - OPUS4-2097 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rurack, Knut A1 - Bricks, J.L. A1 - Kachkovski, A. A1 - Resch-Genger, Ute T1 - Complexing fluorescence probes consisting of various fluorophores linked to 1-aza-15-Crown-5 KW - Fluoroinophore KW - Calcium KW - Sodium KW - Ion sensor KW - Photoinduced electron transfer PY - 1997 SN - 1053-0509 SN - 1573-4994 VL - 7 IS - 1 SP - 63S EP - 66S PB - Plenum Publ. Corp. CY - New York, NY AN - OPUS4-2101 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rurack, Knut A1 - Senoner, Mathias A1 - Resch-Genger, Ute A1 - Dähne, Siegfried T1 - Heavy metal complexes of 2,2'-bipyridyl-3,3'-diol PY - 1994 SN - 0323-598x VL - 21 SP - 683 EP - 684 PB - Akad. Verl. CY - Berlin AN - OPUS4-2103 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Rurack, Knut ED - Resch-Genger, Ute ED - O.S. Wolfbeis, T1 - Fluorescence Quantum Yields:Methods of Determination and Standards N2 - 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. PY - 2008 SN - 978-3-540-75206-6 DO - https://doi.org/10.1007/4243_2008_019 SN - 1617-1306 N1 - Serientitel: Springer Series on Fluorescence – Series title: Springer Series on Fluorescence VL - 5 IS - Part B SP - 101 EP - 145 PB - Springer AN - OPUS4-18445 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rurack, Knut A1 - Resch-Genger, Ute A1 - Rettig, W. T1 - Global analysis of time-resolved emission-a powerful tool for the analytical discrimination of chemically similar ZnII and CdII complexes N2 - 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. KW - Time-resolved KW - Fluorescence KW - ZnII KW - CdII KW - 2,2´-Bipyridyl-3,3´-diol PY - 1998 DO - https://doi.org/10.1016/S1010-6030(98)00369-4 SN - 1010-6030 SN - 1873-2666 VL - 118 IS - 3 SP - 143 EP - 149 PB - Elsevier CY - Lausanne AN - OPUS4-2096 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rurack, Knut A1 - Kollmannsberger, M. A1 - Resch-Genger, Ute A1 - Daub, J. T1 - A selective and sensitive fluoroionophore for HgII, AgI, and CuII with virtually decoupled fluorophore and receptor units KW - Fluoreszenz KW - Ionophor PY - 2000 UR - http://pubs.acs.org/journals/jacsat/index.html SN - 0002-7863 SN - 1520-5126 VL - 122 IS - 5 SP - 968 EP - 969 PB - American Chemical Society CY - Washington, DC AN - OPUS4-2092 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rurack, Knut A1 - Sczepan, M. A1 - Spieles, Monika A1 - Resch-Genger, Ute A1 - Rettig, W. T1 - Correlations between complex stability and charge distribution in the ground state for CaII and NaI complexes of charge transfer (CT) chromo- and fluoroionophores N2 - Several series of crown fluoro-chromo-ionophores covering a broad spectral range are investigated experimentally and compared to their theoretically studied dimethylamino (DMA) analogues. It is shown that the logarithm of the complex stability constants log KS for NaI and CaII ions do not correlate with the observed complexation-induced shift. Likewise, an unsatisfactory correlation is found between the local charge density on the amino nitrogen of the DMA dyes and log KS. However, using the charge of the whole dimethylamino group instead strongly improves this correlation. This can be understood by considering pyramidalization and hyperconjugation effects on the amino nitrogen. The observed correlation allows a novel approach to the design of fluoroionophores with optimized properties. KW - Ionophor KW - Komplex KW - Ladungsverteilung KW - Calcium KW - Natrium PY - 2000 DO - https://doi.org/10.1016/S0009-2614(00)00203-7 SN - 0009-2614 SN - 1873-4448 VL - 320 IS - 1-2 SP - 87 EP - 94 PB - North-Holland Publ. Co. CY - Amsterdam AN - OPUS4-2090 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rurack, Knut A1 - Bricks, J. L. A1 - Reck, Günter A1 - Radeglia, Reiner A1 - Resch-Genger, Ute T1 - Chalcone-analogue dyes emitting in the near-infrared (NIR) - influence of donor-acceptor substitution and cation complexation on their spectroscopic properties and X-ray structure N2 - The photophysical properties of several newly synthesized 1-benzothiazole-3-(4-donor)-phenyl-substituted prop-2-en-1-ones (substituted chalcones) are studied as a function of solvent polarity, temperature, and metal ion by employing steady-state and time-resolved spectroscopy. To investigate the effect of bulkiness and donor strength of the anilino moiety on the spectroscopic properties of these dyes, the spectroscopic behavior of the 4-N-dimethylamino (DMA), the 4-N-tetraoxa-monoaza-15-crown-5 (A15C5), and the 4-N-tetrathia-monoaza-15-crown-5 (AT415C5) derivatives as well as the 3-julolidino (Jul) analogue is compared. Absorption and fluorescence measurements reveal that the strength of the intramolecular charge transfer (ICT) process increases on the order of AT415C5 < A15C5 ~ DMA < Jul. The slight but significant differences between the two crowned dyes are well-supported by the results of the X-ray structure analysis, where oxa aza and thia aza crowns show essentially different geometries. For both fluoroionophores, this variation of heteroatom substitution pattern of the receptor induces specific cation selectivities. The spectroscopic effects accompanying complexation and the different binding sites are studied by steady-state and time-resolved optical spectroscopy as well as NMR spectroscopy. Whereas the probe carrying a tetraoxa monoaza 15-crown-5 receptor shows cation-induced fluorescence enhancement in the presence of alkali and alkaline-earth metal ions, its tetrathia analogue binds selectively to HgII, AgI, and CuII in acetonitrile. Moreover, an increase in fluorescence is observed for the latter probe even upon coordination to the widely known fluorescence quencher HgII. Besides receptor complexation, chelate formation in the benzothiazole-carbonyl acceptor part of these intrinsic fluorescent probes is possible, leading to a chromoionophoric signaling behavior in the near-infrared (NIR). PY - 2000 DO - https://doi.org/10.1021/jp994269k SN - 1089-5639 SN - 1520-5215 VL - 104 IS - 14 SP - 3087 EP - 3109 PB - Soc. CY - Washington, DC AN - OPUS4-2088 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rurack, Knut A1 - Resch-Genger, Ute A1 - Kollmannsberger, M. A1 - Daub, J. A1 - Rettig, W. T1 - Design of an efficient charge-transfer processing molecular system containing a weak electron donor: spectroscopic and redox properties and cation-induced fluorescence enhancement N2 - The acceptor strength of the boron-dipyrromethene chromophore in directly linked donor–acceptor compounds can be tuned by substituents in such a way that a fast excited state charge transfer takes place even for the comparatively weak benzo crown electron donor. This leads to strong fluorescence quenching. Upon binding of cations (Na+ and K+) to the benzo crown receptor, the donor properties of the latter are further reduced, partly suppressing charge transfer. Large fluorescence enhancement factors and cation-selective fluorescence decay times result which are the basis for improved analytical application of these dyes as highly sensitive fluorescent probes. PY - 2000 DO - https://doi.org/10.1016/S0009-2614(00)01058-7 SN - 0009-2614 SN - 1873-4448 VL - 329 IS - 5-6 SP - 363 EP - 369 PB - North-Holland Publ. Co. CY - Amsterdam AN - OPUS4-1049 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rurack, Knut A1 - Resch-Genger, Ute A1 - Rettig, W. T1 - Fluoreszenzmarker für Schwer- und Übergangsmetallionen - Selektivität durch gezieltes Rezeptordesign und ionenspezifische Fluoreszenzverstärkung T2 - Tagung "Tag der Chemie 2000" CY - Potsdam, Deutschland DA - 2000-11-08 KW - Fluoreszenzmarker KW - Schwermetalle KW - Rezeptoren PY - 2000 SP - 87 AN - OPUS4-1016 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Leiterer, Jork A1 - Grabolle, Markus A1 - Rurack, Knut A1 - Resch-Genger, Ute A1 - Ziegler, J. A1 - Nann, T. A1 - Panne, Ulrich T1 - Acoustically Levitated Droplets - A Contactless Sampling Method for Fluorescence Studies N2 - 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. KW - Acoustic levitation KW - Dyes KW - Energy transfer KW - Fluorescence KW - Quantum dots KW - Nanocrystals KW - Ultrasonic trap PY - 2008 DO - https://doi.org/10.1196/annals.1430.039 SN - 0077-8923 SN - 1749-6632 SN - 0094-8500 VL - 1130 SP - 78 EP - 84 PB - New York Academy of Sciences CY - New York, NY AN - OPUS4-17658 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bierstedt, Andreas A1 - Warschat, Carsten A1 - You, Yi A1 - Rurack, Knut A1 - Riedel, Jens T1 - Stimulated Raman scattering by intracavity mixing of nanosecond laser excitation and fluorescence in acoustically levitated droplets N2 - 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. KW - Ultrasonic levitation KW - Stimulated Raman Spectroscopy PY - 2020 DO - https://doi.org/10.1039/D0AY01504K VL - 12 IS - 42 SP - 5046 EP - 5054 PB - Royal Society of Chemistry AN - OPUS4-51566 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gawlitza, Kornelia A1 - Tiebe, Carlo A1 - Banach, Ulrich A1 - Noske, Reinhard A1 - Bartholmai, Matthias A1 - Rurack, Knut T1 - Novel sensor for long-term monitoring of ammonia in gas phase N2 - 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. T2 - 13. Dresdner Sensor-Symposium 2017 CY - Dresden, Germany DA - 04.12.2017 KW - Ammonia gas sensor KW - Fluorescence KW - Air quality monitoring KW - Standard gas generator KW - Miniaturized sensor device PY - 2017 DO - https://doi.org/10.5162/13dss2017/P4.02 SP - P4.02, 272 EP - 276 AN - OPUS4-43352 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sun, Yijuan A1 - Pérez-Padilla, Víctor A1 - Valderrey, Virginia A1 - Bell, Jérémy A1 - Gawlitza, Kornelia A1 - Rurack, Knut T1 - Ratiometric detection of perfluoroalkyl carboxylic acids using dual fluorescent nanoparticles and a miniaturised microfluidic platform N2 - The widespread contamination of soil and water with perfluoroalkyl substances (PFAS) has caused considerable societal and scientific concern. Legislative measures and an increased need for remediation require effective on-site analytical methods for PFAS management. Here we report on the development of a green-fluorescent guanidine-BODIPY indicator monomer incorporated into a molecularly imprinted polymer (MIP) for the selective detection of perfluorooctanoic acid (PFOA). Complexation of PFOA by the indicator, which is mediated by concerted protonation-induced ion pairing-assisted hydrogen bonding, significantly enhances fluorescence in polar organic solvents. The MIP forms as a thin layer on silica nanoparticles doped with tris(bipyridine)ruthenium(II) chloride, which provides an orange emission signal as internal reference, resulting in low measurement uncertainties. Using a liquid-liquid extraction protocol, this assay enables the direct detection of PFOA in environmental water samples and achieves a detection limit of 0.11 µM. Integration into an opto-microfluidic system enables a compact and user-friendly system for detecting PFOA in less than 15 minutes. KW - PFAS KW - Molecular imprinting KW - Microfluidics KW - Fluorescence KW - Onsite assay PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-650270 DO - https://doi.org/10.1038/s41467-025-66872-9 SN - 2041-1723 VL - 16 IS - 1 SP - 1 EP - 16 PB - Springer Science and Business Media LLC AN - OPUS4-65027 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lutz, J.-F. A1 - Thünemann, Andreas A1 - Rurack, Knut T1 - DNA-like "Melting" of Adenine- and Thymine-Functionalized Synthetic Copolymers KW - Polymers KW - Micelles KW - Amyloid beta-peptide KW - Proteins KW - Secondary structure PY - 2005 SN - 0024-9297 SN - 1520-5835 VL - 38 IS - 20 SP - 8124 EP - 8126 PB - American Chemical Society CY - Washington, DC AN - OPUS4-11068 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rurack, Knut T1 - Advanced Onsite Analysis for Point-of-Need Applications: Innovations for Robust, Reliable, and User-Friendly Detection N2 - The advancement of portable analytical assays has transformed onsite analysis in several areas, including food safety, environmental monitoring and forensics. The SARS-CoV-2 pandemic has fueled a need for rapid, onsite solutions that enable immediate decision making without the need for and use of laboratory infrastructure. The integration of mobile devices with advanced cameras and significant computing power improves the accessibility and usability of these tests. However, many current methods are limited to the detection of single parameters. The next challenge is to develop robust multiplexed assays that can analyze multiple parameters simultaneously with high sensitivity. In this lecture, innovative approaches developed at BAM will be presented with a focus on supramolecular chemistry, luminescence detection, nanomaterials and miniaturization of devices. Examples will include mesoporous nanomaterials, gated indicator systems, imprinted polymers, microfluidic devices, test strips and smartphone-based analytical tools, focusing on two use cases, i.e., the detection of contaminants in surface waters and immunoanalytical explosives detection. T2 - International Conference on Emergin Trends in Materials Chemistry CY - Coimbatore, India DA - 03.04.2025 KW - Onsite analysis KW - Rapid tests KW - Mobile devices KW - Supramolecular chemistry KW - Fluorescence PY - 2025 AN - OPUS4-65434 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rurack, Knut T1 - Functional polymeric coatings for sensory applications N2 - The growing demand for the detection of relevant chemical compounds as close as possible to their point of origin—whether in industrial processes, for (civilian or military) security, or for environmental monitoring—has increased the importance of functional polymers with molecular recognition capabilities. These materials must meet practical requirements arising from very different real-world scenarios in which simple, robust, and field-deployable approaches are needed and in which bioanalytical binders often suffer significant performance losses. Polymer recognition matrices therefore serve as an essential complement to established laboratory-based analytical technologies. The realization of rapid and reliable onsite detection places specific demands on material design: polymeric recognition layers must be produced with minimal thickness, integrated onto suitable carrier media, and designed for both selectivity and operational robustness. This presentation will introduce our work on molecularly imprinted polymers (MIPs) that have been specifically developed for the detection of relevant contaminants such as pesticides and perfluorinated compounds. Beyond these target analytes, the presentation will show how such polymer layers can support robust, sustainable diagnostic concepts, and it will outline generalizable design principles that enable their extension to a broad spectrum of analytical challenges. T2 - Institutskolloquium des Instituts für Chemie, Humboldt Universität zu Berlin CY - Berlin, Germany DA - 28.01.2026 KW - Functional organic materials KW - Responsive polymers KW - Sensing KW - Molecularly imprinted polymers PY - 2026 AN - OPUS4-65435 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Prakash, Swayam A1 - Bell, Jérémy A1 - Rurack, Knut T1 - Rapid Onsite Detection of Fecal Contamination in Water Using a Portable Fluorometric Assay N2 - Fecal pollution in water poses significant health risks, especially when contaminated sources are used for drinking and food production. Traditional water quality testing methods are expensive, slow, and require skilled personnel, limiting their accessibility. This work addresses these issues by developing a portable fluorometric assay for the detection of the fecal indicator pigment urobilin (UB). The assay uses silane-functionalized glass fiber strips impregnated with zinc chloride, providing a ‘drop-&-detect’ approach with enhanced fluorescence response mediated by the unique complexation properties of ZnCl2 and UB. This approach allows for the detection of UB at sub-nanomolar concentrations in less than 1 min using a 3D-printed setup with miniaturized optical components powered by a smartphone with its camera as a detector. The results validated with a benchtop fluorometer show the effectiveness of this method. The successful application of this userfriendly, rapid, and sensitive assay to real water samples from three rivers and the influx and efflux of a wastewater treatment plant advances field-based water quality monitoring, meets the WHO’s ASSURED criteria, and supports progress toward the global clean water and sanitation goals. KW - Fecal pigment KW - Fluorescence KW - Signal amplification KW - Surface chemistry KW - Water quality testing PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-655543 DO - https://doi.org/10.1021/acssensors.5c03922 SN - 2379-3694 VL - 11 SP - 1 EP - 9 PB - American Chemical Society CY - Washington, D.C. AN - OPUS4-65554 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hernández-García, María Amparo A1 - Rurack, Knut A1 - Bell, Jérémy T1 - Rapid fabrication of optical elements for sensing applications using a standard SLA printer N2 - The demand for compact, high-performance optical components has driven the development of increasingly sophisticated and miniaturized optical elements, often requiring complex and costly fabrication methods. In this study, we propose a cost-effective and accessible methodology for the fabrication of lenses and free-form optics using a commercially available stereolithography (SLA) 3D printer. A systematic characterisation of six transparent photopolymer resins was conducted in terms of their spectroscopic, optical, and morphological properties, i.e., surface and dimensional properties. The evaluation encompassed parameters such as transmittance, autofluorescence, refractive index, and surface roughness. A straightforward yet resilient printing and post-treatment protocol was formulated, facilitating the fabrication of optical components with over 80% transmittance, minimal intrinsic fluorescence, and surface quality that is compatible with exacting optical applications. The fabricated components demonstrated excellent dimensional fidelity to digital designs and high reproducibility. To demonstrate the versatility of this approach, aspherical, miniaturized, and freeform lenses were designed and integrated into three fluorogenic sensing systems, including oil (strip-based) and chlorine (microfluidic-based) detection platforms, as well as a smartphone-based SARS-CoV-2 biosensor. The integration of customized 3D-printed optics has been demonstrated to enhance signal collection and readout performance, thereby highlighting the potential of this approach to democratize the rapid prototyping and deployment of miniaturized optical systems. This work represents a significant advancement in the field of additive manufacturing, particularly in relation to the development of functional photonic devices. Furthermore, it opens new prospects for sensor applications in biosensing, microfluidics, imaging, and integrated optics. KW - 3D-printing KW - Free-form KW - Prototyping KW - Optical resin KW - Surface finishing KW - Fluorescence KW - Sensor PY - 2026 DO - https://doi.org/10.37188/lam.2026.024 VL - 7 SP - 1 EP - 19 PB - Light Publishing Group CY - Changchun AN - OPUS4-65555 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Descalzo, Ana B. A1 - Ashokkumar, Pichandi A1 - Shen, Z. A1 - Rurack, Knut T1 - On the Aggregation Behaviour and Spectroscopic Properties of Alkylated and Annelated BoronDipyrromethene (BODIPY) Dyes in Aqueous Solution N2 - 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. KW - Aggregates KW - BODIPY KW - Excimers KW - Fluorescence KW - Photophysics PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-497771 DO - https://doi.org/10.1002/cptc.201900235 SN - 2367-0932 VL - 4 IS - 2 SP - 120 EP - 131 PB - WILEY-VCH CY - Weinheim AN - OPUS4-49777 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Liu, H. A1 - Song, W. A1 - Gröninger, Delia A1 - Zhang, L. A1 - Lu, Y. A1 - Chan, K. S. A1 - Zhou, Z. A1 - Rurack, Knut A1 - Shen, Z. T1 - Real-time monitoring of newly acidified organelles during autophagy enabled by reaction-based BODIPY dyes N2 - 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. KW - Autophagy KW - BODIPY KW - Fluorescence KW - Lysosome KW - Real-time imaging PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-498358 UR - https://www.nature.com/articles/s42003-019-0682-1 DO - https://doi.org/10.1038/s42003-019-0682-1 SN - 23993642 VL - 2 SP - 442 PB - Nature Research CY - London AN - OPUS4-49835 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gojani, Ardian A1 - Tobias, Charlie A1 - Hülagü, Deniz A1 - Rurack, Knut A1 - Hodoroaba, Vasile-Dan T1 - Toward determination of the surface roughness of particles from a SEM image N2 - 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. KW - MamaLoCA KW - Core-shell particles KW - Electron microscopy KW - Image processing KW - Particle characterisation KW - Roughness PY - 2021 DO - https://doi.org/10.1017/S1431927621011375 SN - 1431-9276 SN - 1435-8115 VL - 27 IS - Suplement S1 SP - 3302 EP - 3305 PB - Cambridge University Press CY - New York, NY AN - OPUS4-53283 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hülagü, Deniz A1 - Tobias, Charlie A1 - Dao, Radek A1 - Komarov, Pavel A1 - Rurack, Knut A1 - Hodoroaba, Vasile-Dan T1 - Towards 3D determination of the surface roughness of core–shell microparticles as a routine quality control procedure by scanning electron microscopy N2 - AbstractRecently, we have developed an algorithm to quantitatively evaluate the roughness of spherical microparticles using scanning electron microscopy (SEM) images. The algorithm calculates the root-mean-squared profile roughness (RMS-RQ) of a single particle by analyzing the particle’s boundary. The information extracted from a single SEM image yields however only two-dimensional (2D) profile roughness data from the horizontal plane of a particle. The present study offers a practical procedure and the necessary software tools to gain quasi three-dimensional (3D) information from 2D particle contours recorded at different particle inclinations by tilting the sample (stage). This new approach was tested on a set of polystyrene core-iron oxide shell-silica shell particles as few micrometer-sized beads with different (tailored) surface roughness, providing the proof of principle that validates the applicability of the proposed method. SEM images of these particles were analyzed by the latest version of the developed algorithm, which allows to determine the analysis of particles in terms of roughness both within a batch and across the batches as a routine quality control procedure. A separate set of particles has been analyzed by atomic force microscopy (AFM) as a powerful complementary surface analysis technique integrated into SEM, and the roughness results have been compared. KW - Core–shell particles KW - Image analysis KW - Roughness KW - Scanning electron microscopy KW - Atomic force microscopy KW - Tilting KW - Batch analysis PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-607590 DO - https://doi.org/10.1038/s41598-024-68797-7 SN - 2045-2322 VL - 14 IS - 1 SP - 1 EP - 13 PB - Springer Science and Business Media LLC AN - OPUS4-60759 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sarma, Dominik A1 - Mielke, Johannes A1 - Sahre, Mario A1 - Beck, Uwe A1 - Hodoroaba, Vasile-Dan A1 - Rurack, Knut T1 - TSEM-based contour analysis as a tool for the quantification of the profile roughness of silica shells on polystyrene core particles N2 - 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. KW - Core-shell particles KW - Electron microscopy KW - Transmission mode KW - Roughness KW - Image analysis PY - 2017 DO - https://doi.org/10.1016/j.apsusc.2017.07.099 SN - 0169-4332 SN - 1873-5584 VL - 426 IS - 1 SP - 446 EP - 455 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-42256 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hülagü, Deniz A1 - Tobias, Charlie A1 - Gojani, Ardian B. A1 - Rurack, Knut A1 - Hodoroaba, Vasile-Dan T1 - Towards automated scanning electron microscopy image analysis of core-shell microparticles for quasi-3D determination of the surface roughness N2 - 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. T2 - ICASS 5th International Conference on Applied Surface Science CY - Palma, Mallorca, Spain DA - 25.04.2022 KW - Core-shell particles KW - Image analysis KW - Roughness KW - Scanning electron microscopy PY - 2022 AN - OPUS4-54774 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Hülagü, Deniz A1 - Tobias, Charlie A1 - Dao, R. A1 - Komarow, P. A1 - Rurack, Knut A1 - Hodoroaba, Vasile-Dan T1 - Dataset accompanying the publication "Towards 3D determination of the surface roughness of core-shell microparticles as a routine quality control procedure by scanning electron microscopy" N2 - This dataset accompanies the following publication: Hülagü, D., Tobias, C., Dao, R., Komarov, P., Rurack, K., Hodoroaba, V.-D., Towards 3D determination of the surface roughness of core-shell microparticles as a routine quality control procedure by scanning electron microscopy. Sci.Rep, 14, 17936 (2024), https://doi.org/10.1038/s41598-024-68797-7. It contains SEM and AFM-in-SEM images of polystyrene (PS) core particles, polystyrene-iron oxide (PS/Fe3O4) core-shell particles, and polystyrene-iron oxide-silica (PS/Fe3O4/SiO2) core-shell-shell particles. Please refer to the publication and its supporting information for more details on the acquisition and contents of the dataset, as well as the GitHub repository at https://github.Com/denizhulagu/roughness-analysis-by-electron-microscopy. The investigated particles were produced at BAM laboratories as previously described in: Hülagü, D. et al. Generalized analysis approach of the profile roughness by electron microscopy with the example of hierarchically grown polystyrene–iron oxide–silica core–shell–shell particles. Adv. Eng. Mater. 24, 2101344, https://doi.org/10.1002/adem.202101344 (2022). Tobias, C., Climent, E., Gawlitza, K. & Rurack, K. Polystyrene microparticles with convergently grown mesoporous silica shells as a promising tool for multiplexed bioanalytical assays. ACS Appl. Mater. Interfaces 13, 207, https://dx.doi.org/10.1021/acsami.0c17940 (2020). KW - Core–shell particles KW - Image analysis KW - Roughness KW - Scanning electron microscopy KW - Atomic force microscopy KW - Tilting KW - Batch analysis PY - 2024 UR - https://zenodo.org/records/11108726 DO - https://doi.org/10.5281/zenodo.11108725 PB - Zenodo CY - Geneva AN - OPUS4-60760 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zhang, Kun A1 - Carrod, Andrew J. A1 - Del Giorgio, Elena A1 - Hughes, Joseph A1 - Rurack, Knut A1 - Bennet, Francesca A1 - Hodoroaba, Vasile-Dan A1 - Harrad, Stuart A1 - Pikramenou, Zoe T1 - Luminescence Lifetime-Based Sensing Platform Based on Cyclometalated Iridium(III) Complexes for the Detection of Perfluorooctanoic Acid in Aqueous Samples N2 - 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). KW - Perfluorooctanoic Acid (PFOA) KW - Cyclometalated iridium (III) complexes KW - Luminescent lifetime KW - Optically active surfaces KW - ToF-SIMS PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-594535 UR - https://pubs.acs.org/doi/10.1021/acs.analchem.3c04289 DO - https://doi.org/10.1021/acs.analchem.3c04289 VL - 96 IS - 4 SP - 1565 EP - 1575 PB - American Chemical Society (ACS) AN - OPUS4-59453 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sarma, Dominik A1 - Carl, Peter A1 - Climent Terol, Estela A1 - Schneider, Rudolf A1 - Rurack, Knut T1 - Multifunctional polystyrene core/silica shell microparticles with antifouling properties for bead-based multiplexed and quantitative analysis N2 - 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. KW - Core−shell particles KW - Bead-based assay KW - Multiplex KW - Antifouling surface KW - Mixed surface PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-472931 UR - https://pubs.acs.org/doi/10.1021/acsami.8b10306 DO - https://doi.org/10.1021/acsami.8b10306 SN - 1944-8244 VL - 11 IS - 1 SP - 1321 EP - 1334 PB - American Chemical Society CY - Online Library AN - OPUS4-47293 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gotor, Raúl A1 - Bell, Jérémy A1 - Rurack, Knut T1 - Tailored fluorescent solvatochromic test strips for quantitative on-site detection of gasoline fuel adulteration N2 - 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. KW - Gasoline KW - Adulteration KW - Test strips KW - Benzin KW - Teststreifen KW - Fluorescence KW - Cellulose KW - Zellulose KW - Fluoreszenz PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-479231 UR - https://pubs.rsc.org/en/content/articlelanding/2019/tc/c8tc04818e DO - https://doi.org/10.1039/C8TC04818E SN - 2050-7526 VL - 7 IS - 8 SP - 2250 EP - 2256 PB - Royal Society of Chemistry CY - London, UK AN - OPUS4-47923 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bartelmeß, Jürgen A1 - Valderrey, Virginia A1 - Rurack, Knut T1 - Development of a “Turn-on” Fluorescent Probe-Based Sensing System for Hydrogen Sulfide in Liquid and Gas Phase N2 - 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. KW - Sulfide sensing KW - Fluorescence KW - BODIPYs KW - Cobaloxime complex KW - Gas sensing PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-492186 DO - https://doi.org/10.3389/fchem.2019.00641 SN - 2296-2646 VL - 7 SP - Art. Nr. 641 PB - Frontiers Media CY - Lausanne AN - OPUS4-49218 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Carl, Peter A1 - Sarma, Dominik A1 - Gregório, Bruno J. R. A1 - Hoffmann, Kristin A1 - Lehmann, Andreas A1 - Rurack, Knut A1 - Schneider, Rudolf T1 - Wash-Free Multiplexed Mix-and-Read Suspension Array Fluorescence Immunoassay for Anthropogenic Markers in Wastewater N2 - 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. KW - Suspension Array KW - Immunoassay KW - Carbamazepine KW - Caffeine KW - Diclofenac KW - SAFIA PY - 2019 DO - https://doi.org/10.1021/acs.analchem.9b03040 SN - 0003-2700 VL - 91 IS - 20 SP - 12988 EP - 12966 PB - ACS Publications AN - OPUS4-49305 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bell, Jérémy A1 - Tillo, Adam A1 - Chauhan, Vraj P. A1 - Bartelmeß, Jürgen A1 - Rurack, Knut T1 - Microfluidic analytical tool coupling a fluorescent molecular probe and a micro-hydrocyclone for the detection of water chlorination level N2 - 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. T2 - Konferenz CY - Ioannina, Greece DA - 22.09.2019 KW - Chlorine KW - Fluorescence KW - Microfluidics KW - Water KW - Chlor KW - Fluoreszenz KW - Mikrofluidik KW - Wasser PY - 2019 UR - https://media.conferre.gr/index.php/photos-videos/ima2019 AN - OPUS4-49130 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tillo, Adam A1 - Bartelmeß, Jürgen A1 - Chauhan, Vraj P. A1 - Bell, Jérémy A1 - Rurack, Knut T1 - Microfluidic Device for the Determination of Water Chlorination Levels Combining a Fluorescent meso-Enamine Boron Dipyrromethene Probe and a Microhydrocyclone for Gas Bubble Separation N2 - 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. KW - Chlorine KW - BODIPY KW - Fluorescence KW - Micro-Hydrocyclone KW - Microfluidic Chip PY - 2019 DO - https://doi.org/10.1021/acs.analchem.9b03039 SN - 0003-2700 VL - 91 IS - 20 SP - 12980 EP - 12987 PB - American Chemical Society CY - Washington, DC AN - OPUS4-49393 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hülagü, Deniz A1 - Tobias, Charlie A1 - Climent Terol, Estela A1 - Gojani, Ardian A1 - Rurack, Knut A1 - Hodoroaba, Vasile-Dan T1 - Generalized Analysis Approach of the Profile Roughness by Electron Microscopy with the Example of Hierarchically Grown Polystyrene–Iron Oxide–Silica Core–Shell–Shell Particles N2 - 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. KW - Core–shell particles KW - Image analysis KW - Nanoparticles KW - Roughness KW - SEM KW - transmission mode PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-542576 DO - https://doi.org/10.1002/adem.202101344 SP - 1 EP - 9 PB - Wiley-VCH AN - OPUS4-54257 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hülagü, Deniz A1 - Tobias, Charlie A1 - Gojani, Ardian B. A1 - Rurack, Knut A1 - Hodoroaba, Vasile-Dan T1 - From 2D and Single Particle to 3D and Batch Analysis as a Routine Quality Check Procedure for the Morphological Characterization of Core-Shell Microparticles N2 - 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. T2 - Microscopy and Microanalysis 2022 CY - Oregon, Portland, USA DA - 31.07.2022 KW - Core-shell particles KW - Image processing KW - Roughness KW - Scanning electron microscopy KW - Tilting PY - 2022 DO - https://doi.org/10.1017/S1431927622002094 SN - 1431-9276 VL - 28 IS - S1 SP - 332 EP - 334 PB - Cambridge University Press AN - OPUS4-55373 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hülagü, Deniz A1 - Tobias, Charlie A1 - Gojani, Ardian A1 - Rurack, Knut A1 - Hodoroaba, Vasile-Dan T1 - Analysis of the profile roughness of core-shell microparticles by electron microscopy N2 - 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. KW - Core-shell particles KW - Electron microscopy KW - Image processing KW - MamaLoCa KW - Particle Characterization KW - Roughness PY - 2021 DO - https://doi.org/10.1017/S1431927621007285 VL - 27 IS - Suppl. 1 SP - 2002 EP - 2004 PB - Cambridge University Press AN - OPUS4-53123 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gawlitza, Kornelia A1 - Johann, Sergej A1 - Mansurova, Maria A1 - Kohlhoff, Harald A1 - Tiebe, Carlo A1 - Bell, Jérémy A1 - Bartholmai, Matthias A1 - Rurack, Knut T1 - Semi-automatic Measurement Device for Long-Term Monitoring of Ammonia in Gas Phase N2 - 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. T2 - SMSI 2021 CY - Online meeting DA - 03.05.2021 KW - Spectroscopy KW - Embedded sensor KW - Environment KW - Air quality PY - 2021 SP - 133 EP - 134 AN - OPUS4-52576 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gawlitza, Kornelia A1 - Johann, Sergej A1 - Mansurova, M. A1 - Kohlhoff, Harald A1 - Tiebe, Carlo A1 - Bell, Jérémy A1 - Bartholmai, Matthias A1 - Rurack, Knut T1 - Semi-automatic Measurement Device for Long-Term Monitoring of Ammonia in Gas Phase N2 - 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. T2 - SMSI 2020 CY - Meeting was canceled KW - Spectroscopy KW - Emmbedded sensor KW - Environment KW - Air quality PY - 2020 DO - https://doi.org/10.5162/SMSI2020/B5.4 SP - 133 EP - 134 AN - OPUS4-50867 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -