TY - JOUR A1 - Wang, Cui A1 - Kitzmann, W.R. A1 - Weigert, Florian A1 - Förster, Ch. A1 - Wang, X. A1 - Heintze, K. A1 - Resch-Genger, Ute T1 - Matrix Effects on Photoluminescence and Oxygen Sensitivity of a Molecular Ruby N2 - The molecular ruby analogue [Cr(ddpd)2]3+ (ddpd=N,N’-dimethyl-N,N’-dipyridine-2-ylpyridine-2,6-diamine) exhibits near infrared (NIR) emission with a high photoluminescence (PL) quantum yield ΦPL of 11 % and a lifetime of 898 μs in deaerated water at room temperature. While ligand-based control of the photophysical properties has received much attention, influences of the counter anions and microenvironment are still underexplored. In this study, the luminescence properties of the molecular ruby were systematically examined for the counter anions Cl−, Br−, [BF4]−, [PF6]−, [BPh4]−, and [BArF24]− in acetonitrile (MeCN) solution, in crystals, and embedded into polystyrene nanoparticles (PSNP). Stern-Volmer analyses of the oxygen quenching studies in the intensity and lifetime domain showed the highest oxygen sensitivity of the complexes with the counter anions of [BF4]− and [BArF24]−, which also revealed the longest luminescence lifetimes. Embedding [Cr(ddpd)2][PF6]3 in PSNPs and shielding with poly(vinyl alcohol) yields a strongly NIR-emissive oxygen-insensitive material with a record ΦPL of 15.2 % under ambient conditions. KW - Fluorescence KW - Sensor KW - Oxygen KW - Quantum yield KW - Quality assurance KW - Complex KW - Cr(III) KW - Lifetime KW - Ligand KW - Solid state KW - X-Ray analysis KW - Structure-property relationship KW - Nano KW - Polymer KW - Particle PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-546057 DO - https://doi.org/10.1002/cptc.202100296 SN - 2367-0932 VL - 6 IS - 6 SP - 1 EP - 9 PB - Wiley-VCH CY - Weinheim AN - OPUS4-54605 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Witte, F. A1 - Rietsch, P. A1 - Nirmalananthan-Budau, Nithiya A1 - Weigert, Florian A1 - Götze, J. P. A1 - Resch-Genger, Ute A1 - Eigler, S. A1 - Paulus, B. T1 - Aggregation-induced emission leading to two distinct emissive species in the solid-state structure of high-dipole organic chromophores N2 - The concept of aggregation-induced emission represents a means to rationalise photoluminescence of usually nonfluorescent excimers in solid-state materials. In this publication, we study the photophysical properties of selected diaminodicyanoquinone (DADQ) derivatives in the solid state using a combined approach of experiment and theory. DADQs are a class of high-dipole organic chromophores promising for applications in non-linear optics and light-harvesting devices. Among the compounds investigated, we find both aggregation-induced emission and aggregation-caused quenching effects rationalised by calculated energy transfer rates. Analysis of fluorescence spectra and lifetime measurements provide the interesting result that (at least) two emissive species seem to contribute to the photophysical properties of DADQs. The main emission peak is notably broadened in the long-wavelength limit and exhibits a blue-shifted shoulder. We employ high-level quantum-chemical methods to validate a molecular approach to a solid-state problem and show that the complex emission features of DADQs can be attributed to a combination of H-type aggregates, monomers, and crystal structure defects. KW - Fluorescence KW - Optical probe KW - Dye KW - Photophysics KW - Theory KW - Quantum yield KW - Mechanism KW - Quantum chemistry KW - Modelling KW - Aggregation KW - Lifetime KW - Single particle KW - Microscopy KW - Solid KW - Crystal PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-531138 DO - https://doi.org/10.1039/d1cp02534a SP - 1 EP - 9 PB - Royal Society of Chemistry AN - OPUS4-53113 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Resch-Genger, Ute A1 - Meermann, Björn A1 - Koch, Matthias A1 - Weller, Michael G. T1 - Editorial: Analytical methods and applications in materials and life sciences N2 - Current trends in materials and life sciences are flanked by the need to push detection limits to single molecules or single cells, enable the characterization of increasingly complex matrices or sophisticated nanostructures, speed up the time of analysis, reduce instrument complexity and costs, and improve the reliability of data. This requires suitable analytical tools such as spectroscopic, separation and imaging techniques, mass spectrometry, and hyphenated techniques as well as sensors and their adaptation to application-specific challenges in the environmental, food, consumer product, health sector, nanotechnology, and bioanalysis. Increasing concerns about health threatening known or emerging pollutants in drinking water, consumer products, and food and about the safety of nanomaterials led to a new awareness of the importance of analytical sciences. Another important driver in this direction is the increasing demand by legislation, particularly in view of the 17 sustainable development goals by the United Nations addressing clean energy, industry, and innovation, sustainable cities, clean water, and responsible consumption and production. In this respect, also the development of analytical methods that enable the characterization of material flows in production processes and support recycling concepts of precious raw materials becomes more and more relevant. In the future, this will provide the basis for greener production in the chemical industry utilizing recycled or sustainable starting materials. This makes analytical chemistry an essential player in terms of the circular economy helping to increase the sustainability of production processes. In the life sciences sector, products based on proteins, such as therapeutic and diagnostic antibodies, increase in importance. These increasingly biotechnologically produced functional biomolecules pose a high level of complexity of matrix and structural features that can be met only by highly advanced methods for separation, characterization, and detection. In addition, metrological traceability and target definition are still significant challenges for the future, particularly in the life sciences. However, innovative reference materials as required for the health and food sector and the characterization of advanced materials can only be developed when suitable analytical protocols are available. The so-called reproducibility crisis in sciences underlines the importance of improved measures of quality control for all kinds of measurements and material characterization. This calls for thorough method validation concepts, suitable reference materials, and regular interlaboratory comparisons of measurements as well as better training of scientists in analytical sciences. The important contribution of analytical sciences to these developments is highlighted by a broad collection of research papers, trend articles, and critical reviews from these different application fields. Special emphasis is dedicated to often-overlooked quality assurance and reference materials. T2 - 150 years BAM: Science with impact CY - Berlin, Germany DA - 01.01.2021 KW - Analysis KW - Life sciences KW - Analytical sciences KW - Quality assurance KW - Reference material KW - Fluorescence KW - Nanoparticle KW - Sensor KW - Material sciences KW - Pollutant KW - Environment KW - Method KW - Limit of detection KW - 150th anniversary KW - ABC KW - BAM KW - Collection KW - Editorial KW - Special issue KW - Bundesanstalt für Materialforschung und -prüfung KW - Jahrestag PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-550720 DO - https://doi.org/10.1007/s00216-022-04082-8 SN - 1618-2642 SN - 1618-2650 VL - 414 IS - Topical collection: Analytical methods and applications in the materials and life sciences SP - 4267 EP - 4268 PB - Springer CY - Berlin AN - OPUS4-55072 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - López-Puertollano, Daniel A1 - Tobias, Charlie A1 - Bell, Jérémy A1 - Abad-Somovilla, A. A1 - Abad-Fuentes, A. A1 - Rurack, Knut T1 - Superparamagnetic Bead-Based Microfluidic Fluoroimmunoassay Platform for Rapid Ochratoxin A Detection in Flour N2 - Simplification and reduction of time and costs are the primary goals in the development and use of onsite methods in diagnostics and food safety. To facilitate the transition from laboratory techniques to simple, miniaturized devices, we have developed a modular microfluidic platform. This platform integrates a competitive fluorescence immunoassay on the surface of superparamagnetic beads, serving as a complementary technique to traditional cytometry assays. In the first chip module, a fast competitive reaction (5 min) occurs, after which the particles are retained in the second module. This module consists of a PDMS chip and a permanent magnet, allowing only the fluorescent competitor to reach the detection module. Ochratoxin A (OTA) was chosen as the model analyte for device development, using fluorescein-labeled OTA as a competitor. The system efficiently separates particles, with OTA concentration directly correlated to the amount of fluorescent competitor remaining in solution after the competitive reaction. This innovative setup allows to perform rapid measurements with small sample volumes in a short time (10 min), achieving a limit of detection for OTA of 1.2 μg L–1. The system was successfully applied to the accurate determination of OTA in wheat flour spiked at regulatorily relevant concentrations. Using this device, conventional cytometry immunoassays can be seamlessly transformed into user-friendly, miniaturized analytical methods at reduced cost for applications outside of a laboratory directly at the point of need. KW - Bead-based assay KW - Fluorescence KW - Immunoassay KW - Microfluidics KW - mycotoxins PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-638472 DO - https://doi.org/10.1021/acssensors.5c01119 SN - 2379-3694 SP - 1 EP - 10 PB - American Chemical Society CY - Washington, D.C. AN - OPUS4-63847 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sun, Yijuan A1 - Gawlitza, Kornelia A1 - Valderrey, Virginia A1 - Bell, Jérémy A1 - Rurack, Knut T1 - Polymerizable BODIPY probe crosslinker for the molecularly imprinted polymer-based detection of organic carboxylates via fluorescence N2 - This contribution reports the development of a polymerizable BODIPY-type fluorescent probe targeting small-molecule carboxylates for incorporation into molecularly imprinted polymers (MIPs). The design of the probe crosslinker includes a urea recognition site p-conjugated to the 3-position of the BODIPY core and two methacrylate moieties. Titration experiments with a carboxylate-expressing antibiotic, levofloxacin (LEVO), showed a blue shift of the absorption band as well as a broadening and decrease in emission, attributed to hydrogen bonding between the probe’s urea group and the carboxylate group of the antibiotic. Using this probe crosslinker, core–shell particles with a silica core and a thin MIP shell were prepared for the detection of LEVO. The MIP exhibited highly selective recognition of LEVO, with an imprinting factor of 18.1 compared to the non-imprinted polymer. Transmission electron microscopy confirmed the core–shell structure and spectroscopic studies revealed that the receptor’s positioning leads to a unique perturbation of the polymethinic character of the BODIPY chromophore, entailing the favourable responses. These features are fully preserved in the MIP, whereas no such response was observed for competitors such as ampicillin. The sensory particles allowed to detect LEVO down to submicromolar concentrations in dioxane. We have developed here for the first time a BODIPY probe for organic carboxylates and incorporated it into polymers using the imprinting technique, paving the way for BODIPY-type fluorescent MIP sensors. KW - Fluorescence KW - BODIPY probe KW - Molecularly Imprinted Polymers KW - Sensor Materials KW - Dyes KW - Water analysis KW - Advanced materials PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-598629 DO - https://doi.org/10.1039/D3MA00476G SP - 1 EP - 11 PB - Royal Society of Chemistry (RSC) AN - OPUS4-59862 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mansurova, Maria A1 - Gotor, Raúl A1 - Johann, Sergej A1 - Neumann, Patrick P. A1 - Bartholmai, Matthias A1 - Rurack, Knut A1 - Bell, Jérémy T1 - Fluorescent Hydrophobic Test Strips with Sterically Integrated Molecular Rotors for the Detection of Hydrocarbons in Water and Soil with an Embedded Optical Read-Out N2 - 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. KW - Test strip KW - Sensor KW - Smartphone KW - Fluorescence KW - Test Streifen KW - Sensoren KW - Fluoreszenz KW - Petrol KW - Öl PY - 2023 DO - https://doi.org/10.1021/acs.energyfuels.3c01175 SN - 0887-0624 SP - 1 EP - 6 PB - American Chemical Society CY - Washington, United States AN - OPUS4-57892 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Yanbaeva, M. A1 - Soyka, J. A1 - Holthoff, J. M. A1 - Rietsch, P. A1 - Engelage, E. A1 - Ruff, A. A1 - Resch-Genger, Ute A1 - Weiss, R. A1 - Eigler, S. A1 - Huber, S. M. T1 - Dimethylene-Cyclopropanide Units as Building Blocks for Fluorescence Dyes N2 - Many organic dyes are fluorescent in solution. In the solid state, however, quenching processes often dominate, hampering material science applications such as light filters, light-emitting devices, or coding tags. We show that the dimethylene-cyclopropanides caffold can be used to form two structurally different types of chromophores, which feature fluorescence quantum yields up to 0.66 in dimethyl sulfoxide and 0.53 in solids. The increased fluorescence in the solid state for compounds bearing malonate substituents instead of dicyanomethide ones is rationalized by the induced twist between the planes of the cyclopropanide core and a pyridine ligand. KW - Fluorescence KW - Dye KW - Sensor KW - Quantum yield KW - Spectroscopy KW - Photophysics KW - Synthesis KW - Solvatochromism PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-614931 DO - https://doi.org/10.1002/chem.202402476 VL - 30 IS - 56 SP - 1 EP - 7 PB - Chemistry - A European Journal AN - OPUS4-61493 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Scholtz, Lena A1 - Eckert, J. G. A1 - Elahi, T. A1 - Lübkemann, F. A1 - Hübner, Oskar A1 - Bigall, N. C. A1 - Resch-Genger, Ute T1 - Luminescence encoding of polymer microbeads with organic dyes and semiconductor quantum dots during polymerization N2 - Luminescence-encoded microbeads are important tools for many applications in the life and material sciences that utilize luminescence detection as well as multiplexing and barcoding strategies. The preparation of such beads often involves the staining of premanufactured beads with molecular luminophores using simple swelling procedures or surface functionalization with layer-by-layer (LbL) techniques. Alternatively, these luminophores are sterically incorporated during the polymerization reaction yielding the polymer beads. The favorable optical properties of semiconductor quantum dots (QDs), which present broadly excitable, size-tunable, narrow emission bands and low photobleaching sensitivity, triggered the preparation of beads stained with QDs. However, the colloidal nature and the surface chemistry of these QDs, which largely controls their luminescence properties, introduce new challenges to bead encoding that have been barely systematically assessed. To establish a straightforward approach for the bead encoding with QDs with minimized loss in luminescence, we systematically assessed the incorporation of oleic acid/oleylamine-stabilized CdSe/CdS-core/shell-QDs into 0.5–2.5 μm-sized polystyrene (PS) microspheres by a simple dispersion polymerization synthesis that was first optimized with the organic dye Nile Red. Parameters addressed for the preparation of luminophore-encoded beads include the use of a polymer-compatible ligand such as benzyldimethyloctadecylammonium chloride (OBDAC) for the QDs, and crosslinking to prevent luminophore leakage. The physico-chemical and optical properties of the resulting beads were investigated with electron microscopy, dynamic light scattering, optical spectroscopy, and fluorescence microscopy. Particle size distribution, fluorescence quantum yield of the encapsulated QDs, and QD leaking stability were used as measures for bead quality. The derived optimized bead encoding procedure enables the reproducible preparation of bright PS microbeads encoded with organic dyes as well as with CdSe/CdS-QDs. Although these beads show a reduced photoluminescence quantum yield compared to the initially very strongly luminescent QDs, with values of about 35%, their photoluminescence quantum yield is nevertheless still moderate. KW - Polymerization KW - Quantum dots KW - Microbeads KW - Fluorescence PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-553430 DO - https://doi.org/10.1038/s41598-022-16065-x SN - 2045-2322 VL - 12 SP - 1 EP - 16 PB - Nature Publishing Group CY - London AN - OPUS4-55343 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kromer, C. A1 - Schwibbert, Karin A1 - Gadicherla, A. K. A1 - Thiele, Dorothea A1 - Nirmalananthan-Budau, Nithiya A1 - Laux, P. A1 - Resch-Genger, Ute A1 - Luch, A. A1 - Tschiche, H. R. T1 - Monitoring and imaging pH in biofilms utilizing a fluorescent polymeric nanosensor N2 - Biofilms are ubiquitous in nature and in the man-made environment. Given their harmful effects on human health, an in-depth understanding of biofilms and the monitoring of their formation and growth are important. Particularly relevant for many metabolic processes and survival strategies of biofilms is their extracellular pH. However, most conventional techniques are not suited for minimally invasive pH measurements of living biofilms. Here, a fluorescent nanosensor is presented for ratiometric measurements of pH in biofilms in the range of pH 4.5–9.5 using confocal laser scanning microscopy. The nanosensor consists of biocompatible polystyrene nanoparticles loaded with pH-inert dye Nile Red and is surface functionalized with a pH-responsive fluorescein dye. Its performance was validated by fluorometrically monitoring the time-dependent changes in pH in E. coli biofilms after glucose inoculation at 37 °C and 4 °C. This revealed a temperature-dependent decrease in pH over a 4-h period caused by the acidifying glucose metabolism of E. coli. These studies demonstrate the applicability of this nanosensor to characterize the chemical microenvironment in biofilms with fluorescence methods. KW - Dye KW - Fluorescence KW - Signal enhancement KW - Sensor KW - Quantum yield KW - Synthesis KW - Nanoparticle KW - Nano KW - Polymer KW - Ph KW - Biofilm KW - MIC KW - Corrosion KW - Microorganism KW - Bacteria PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-550751 DO - https://doi.org/10.1038/s41598-022-13518-1 SN - 2045-2322 VL - 12 IS - 1 SP - 1 EP - 10 PB - Nature Publishing Group CY - London AN - OPUS4-55075 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stein, L. A1 - Wang, Cui A1 - Förster, C. A1 - Resch-Genger, Ute A1 - Heinze, K. T1 - Bulky ligands protect molecular ruby from oxygen quenching N2 - Chromium(III) complexes can show phosphorescence from the spin-flip excited doublet states 2E/2T1 in the near-infrared with high photoluminescence quantum yields and extremely long lifetimes in the absence of dioxygen. The prototype molecular ruby, [Cr(ddpd)2]3+ (ddpd = N,N’-dimethyl-N,N’-dipyridine-2-ylpyridine-2,6-diamine), has a photoluminescence quantum yield and a luminescence lifetime of 13.7% and 1.1 ms in deaerated acetonitrile, respectively. However, its luminescence is strongly quenched by 3O2 via an efficient Dexter-type energy transfer process. To enable luminescence applications of molecular rubies in solution under aerobic conditions, we explored the potential of sterically demanding ddpd ligands to shield the chromium(III) center from O2 using steady state and time-resolved photoluminescence spectroscopy. The structures of the novel complexes with sterically demanding ligands were investigated by single crystal X-ray diffraction and quantum chemically by density functional theory calculations. The O2 sensitivity of the photoluminescence was derived from absolutely measured photoluminescence quantum yields and excited state lifetimes under inert and aerobic conditions and by Stern–Volmer analyses of these data. Optimal sterically shielded chromium(III) complexes revealed photoluminescence quantum yields of up to 5.1% and excited state lifetimes of 518 μs in air-saturated acetonitrile, underlining the large potential of this ligand design approach to broaden the applicability of highly emissive chromium(III) complexes. KW - Fluorescence KW - Synthesis KW - Production KW - Optical spectroscopy KW - Ligand KW - Photophysics KW - Cr(III) KW - Mechanism KW - NIR KW - Sensor KW - Oxygen PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-570807 DO - https://doi.org/10.1039/d2dt02950b VL - 51 IS - 46 SP - 17664 EP - 17670 PB - The Royal Society of Chemistry CY - Berlin AN - OPUS4-57080 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -