TY - CONF A1 - Ashokkumar, Pichandi A1 - Rurack, Knut T1 - Organic-Inoranic hybrid host materials for fluorescence sensing of anions in aqueous media T2 - Netzwerktagung der Alexander von Humboldt-Stiftung CY - Karlsruhe, Germany DA - 2012-11-28 PY - 2012 AN - OPUS4-27229 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ashokkumar, Pichandi A1 - Rurack, Knut T1 - Test strip-based fluorometric detection of fluoride in aqueous media with a BODIPY-linked hydrogen bonding receptor T2 - Alexander-von-Humboldt-Stiftung Network-Meeting CY - Berlin, Germany DA - 2014-04-09 PY - 2014 AN - OPUS4-30788 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ashokkumar, Pichandi A1 - Rurack, Knut T1 - Fluor on Tour - Schnelltests für die Fluorid-Bestimmung in Wasser N2 - 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. KW - Fluorid KW - Fluoreszenz KW - Schnelltest KW - Teststreifen-Assay KW - Wasser PY - 2014 UR - http://www.git-labor.de/forschung/chemie-physik/fluor-tour SN - 0016-3538 VL - 7 SP - 30 EP - 33 PB - GIT-Verlag CY - Darmstadt AN - OPUS4-32013 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ashokkumar, Pichandi A1 - Weißhoff, Hardy A1 - Kraus, Werner A1 - Rurack, Knut T1 - Test-strip-based fluorometric detection of fluoride in aqueous media with a BODIPY-linked hydrogen-bonding receptor N2 - 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. KW - Amidothiourea KW - Fluorescent probes KW - Fluoride KW - Hydrogen bonds KW - Photoinduced electron transfer PY - 2014 U6 - https://doi.org/10.1002/anie.201307848 SN - 1433-7851 SN - 1521-3773 SN - 0570-0833 VL - 53 IS - 8 SP - 2225 EP - 2229 PB - Wiley-VCH CY - Weinheim AN - OPUS4-31936 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ashokkumar, Pichandi A1 - Weißhoff, Hardy A1 - Kraus, Werner A1 - Rurack, Knut T1 - Fluorometrischer Nachweis von Fluorid in wässriger Lösung mittels Teststreifen und einem BODIPY-Wasserstoffbrückenrezeptor-Konjugat N2 - 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. KW - Amidothioharnstoff KW - Fluoreszenzsonden KW - Fluorid KW - Photoinduzierter Elektronentransfer KW - Wasserstoffbrücken PY - 2014 U6 - https://doi.org/10.1002/ange.201307848 SN - 0044-8249 SN - 0932-2140 SN - 1521-3757 VL - 126 IS - 8 SP - 2257 EP - 2261 PB - Wiley-VCH CY - Weinheim AN - OPUS4-31939 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ashokkumar, Pichandi A1 - Bell, Jérémy A1 - Buurman, Merwe A1 - Rurack, Knut T1 - Analytical platform for sugar sensing in commercial beverages using a BODIPY fluorescent probe N2 - The determination of sugar content in beverages is of paramount importance as consumers are very concerned about the quality, sugar uptake and aroma of the beverages. Fluorescent probes with boronic acid receptors are widely used as sugar sensors. However, most of these probes suffer from weak signaling responses and it requires to carry out the assay at pH >8.8. Development of a BODIPY probe functionalized with a boronic acid receptor carrying an adjacent tertiary amino group to create more basic environment and to have enhanced fluorescence response. Integration of the probe with a miniaturized microfluidic system. Quantitative online measurement of sugar content in commercial beverages with high sensitivity. T2 - ANAKON 2015 CY - Graz, Österreich DA - 2015-03-23 PY - 2015 AN - OPUS4-34775 LA - deu 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 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-497771 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 - Alnajjar, M. A. A1 - Bartelmeß, Jürgen A1 - Hein, R. A1 - Ashokkumar, Pichandi A1 - Nilam, M. A1 - Nau, W. M. A1 - Rurack, Knut A1 - Hennig, A. T1 - Rational design of boron-dipyrromethene (BODIPY) reporter dyes for cucurbit[7]uril N2 - 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. KW - BODIPY KW - Cucurbituril KW - Fluorescence KW - PH KW - Photoinduced Electron Transfer KW - Supramolecular Chemistry PY - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-456361 UR - https://www.beilstein-journals.org/bjoc/content/pdf/1860-5397-14-171.pdf SN - 1860-5397 VL - 14 SP - 1961 EP - 1971 PB - Beilstein-Institut CY - Frankfurt a. M. AN - OPUS4-45636 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gotor, Raul A1 - Ashokkumar, Pichandi A1 - Hecht, Mandy A1 - Keil, Karin A1 - Rurack, Knut T1 - 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 N2 - 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. KW - Fluorescence KW - pH measurement KW - BODIPY KW - Smartphone KW - Test strip PY - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-422571 SN - 0003-2700 SN - 1520-6882 VL - 89 IS - 16 SP - 8437 EP - 8444 PB - American Chemical Society CY - Washington, D.C., USA AN - OPUS4-42257 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ashokkumar, Pichandi A1 - Bell, Jérémy A1 - Buurman, Merwe A1 - Rurack, Knut T1 - Analytical platform for sugar sensing in commercial beverages using a fluorescent BODIPY "light-up" probe N2 - 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. KW - BODIPY dyes KW - Boronic acid KW - Fluorescence KW - Microfluidics KW - Sugars PY - 2018 U6 - https://doi.org/10.1016/j.snb.2017.09.201 SN - 0925-4005 VL - 256 SP - 609 EP - 615 PB - Elsevier CY - Amsterdam AN - OPUS4-43102 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -