TY - CONF A1 - Hoffmann, Katrin A1 - Resch-Genger, Ute A1 - Marlow, Frank T1 - Reversible Photosensitive Refractive Index Changes of Chromophor/Zeolite Nanocomposites T2 - Abschlußkolloquium "Nanostrukturierte Wirt/Gast-Systeme" CY - Berlin, Germany DA - 2002-10-21 PY - 2002 AN - OPUS4-1753 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kage, Daniel A1 - Hoffmann, Katrin A1 - Wittkamp, M. A1 - Ameskamp, J. A1 - Göhde, W. A1 - Resch-Genger, Ute T1 - Luminescence lifetime encoding in time-domain flow cytometry N2 - Time-resolved flow cytometry represents an alternative to commonly applied spectral or intensity multiplexing in bioanalytics. At present, the vast majority of the reports on this topic focuses on phase-domain techniques and specific applications. In this report, we present a flow cytometry platform with time-resolved detection based on a compact setup and straightforward time-Domain measurements utilizing lifetime-encoded beads with lifetimes in the nanosecond range. We provide general assessment of time-domain flow cytometry and discuss the concept of this platform to address achievable resolution limits, data analysis, and requirements on suitable encoding dyes. Experimental data are complemented by numerical calculations on photon count numbers and impact of noise and measurement time on the obtained lifetime values. KW - Flow cytometry KW - Fluorescence KW - Life sciences KW - Lifetime encoding KW - Polymer particles PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-465765 DO - https://doi.org/10.1038/s41598-018-35137-5 SN - 2045-2322 VL - 8 IS - 1 SP - 16715, 1 EP - 11 PB - Nature CY - London AN - OPUS4-46576 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rietsch, P. A1 - Zeyat, M. A1 - Hübner, Oskar A1 - Hoffmann, Katrin A1 - Resch-Genger, Ute A1 - Kutter, M. A1 - Paskin, A. A1 - Uhlig, J. A1 - Lentz, D. A1 - Eigler, S. T1 - Substitution Pattern-Controlled Fluorescence Lifetimes of Fluoranthene Dyes N2 - The absorption and emission properties of organic dyes are generally tuned by altering the substitution pattern. However, tuning the fluorescence lifetimes over a range of several 10 ns while barely affecting the spectral features and maintaining a moderate fluorescence quantum yield is challenging. Such properties are required for lifetime multiplexing and barcoding applications. Here, we show how this can be achieved for the class of fluoranthene dyes, which have substitution-dependent lifetimes between 6 and 33 ns for single wavelength excitation and emission. We explore the substitution-dependent emissive properties in the crystalline solid state that would prevent applications. Furthermore, by analyzing dye mixtures and embedding the dyes in carboxyfunctionalized 8 μm-sized polystyrene particles, the unprecedented potential of these dyes as labels and encoding fluorophores for time-resolved fluorescence detection techniques is demonstrated. KW - Fluorescence KW - Label KW - Fluoranthene KW - Quantum yield KW - Reporter KW - Crystal KW - Encoding KW - Multiplexing KW - Particle KW - Bead KW - Lifetime KW - Dye KW - Barcoding PY - 2021 DO - https://doi.org/10.1021/acs.jpcb.0c08851 SN - 1520-5207 VL - 125 IS - 4 SP - 1207 EP - 1213 PB - American Chemical Society AN - OPUS4-52087 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hoffmann, Katrin T1 - Fluorescence microscopic and spetroscopic studies on functionalized polymer-supports labeled with amino sensitive fluorophores T2 - Focus on Microscopy (FoM) CY - Valencia, Spain DA - 2007-04-10 PY - 2007 AN - OPUS4-14864 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Preiss, J. A1 - Kage, Daniel A1 - Hoffmann, Katrin A1 - Martínez, T. J. A1 - Resch-Genger, Ute A1 - Presselt, M. T1 - Ab initio prediction of fluorescence lifetimes involving solvent environments by means of COSMO and vibrational broadening N2 - The fluorescence lifetime is a key property of fluorophores that can be utilized for microenvironment probing, analyte sensing, and multiplexing as well as barcoding applications. For the rational design of lifetime probes and barcodes, theoretical methods have been developed to enable the ab initio prediction of this parameter, which depends strongly on interactions with solvent molecules and other chemical species in the emitters' immediate environment. In this work, we investigate how a conductor-like screening model (COSMO) can account for variations in fluorescence lifetimes that are caused by such fluorophore−solvent interactions. Therefore, we calculate vibrationally broadened fluorescence spectra using the nuclear ensemble method to obtain distorted molecular geometries to sample the electronic transitions with time-dependent density functional theory (TDDFT). The influence of the solvent on fluorescence lifetimes is accounted for with COSMO. For example, for 4-hydroxythiazole fluorophore containing different heteroatoms and acidic and basic moieties in aprotic and protic solvents of varying polarity, this approach was compared to experimentally determined lifetimes in the same solvents. Our results demonstrate a good correlation between theoretically predicted and experimentally measured fluorescence lifetimes except for the polar solvents Ethanol and acetonitrile that can specifically interact with the heteroatoms and the carboxylic acid of the thiazole derivative. KW - Fluorescence lifetime KW - Ab initio calculation KW - COSMO KW - Conductor-like screening model PY - 2018 DO - https://doi.org/10.1021/acs.jpca.8b08886 SN - 1089-5639 SN - 1520-5215 VL - 122 IS - 51 SP - 9813 EP - 9820 PB - American Chemical Society CY - Washington, DC AN - OPUS4-47177 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Resch-Genger, Ute A1 - Hoffmann, Katrin A1 - Pauli, Jutta ED - Brahme, A. T1 - Signal-relevant properties of fluorescent labels and optical probes and their determination N2 - Luminescence techniques are among the most populär analytical and detection tools in the life Sciences (Das et al., 2012; Kobayashi et al., 2010; Lakowicz, 2006; Weissleder and Pittet, 2008). The ever-growing interest in these methods that yield fluorophore-specific quantities such as emission and excitation spectra, fluorescence quantum yields, fluorescence lifetimes, and emission anisotropies is due to their comparable ease of use; noninvasive character; potential for combining spectrally, temporally, and spatially resolved ineasurements; and suitability for multiplexing and remote sensing (Resch-Genger et al., 2005a). Moreover, fluorescence detection techniques can provide sensitivity down to the single-molecule level. As the vast majority of analytes or targets of interest are nonfluorescent and most endogenous chromophores typically display rather low fluorescence quantum yields, the tremendous analytical potential of photoluminescence techniques initiated also the development of an ever-growing number of fluorescent labels and probes as readily available tools for a broad variety of analytes and applications and the labeling of biomolecules such as oligonucleotides, antibodies, or peptides as detailed in the chapter "Fluorescent Reporters and Optical Probes: Dye Conjugation Chemistry, Spectroscopic Properties, and Design Concepts" (Berezin and Achilefu, 2010; Escobedo et al., 2010; Luo et al., 2011; Resch-Genger and Licha, 2011; Resch-Genger et al., 2008). Prominent examples of such dye-biomolecule conjugates are fluorophore-labeled secondary antibodies, for example, for immunohistochemistry or flow cytometry, and conventional contrast agents, consisting of a fluorescent reporter and a biomarker-specific biomolecule like a peptide, antibody, or antibody fragment for in vivo near-infrared (NIR) fluorescence imaging of pathological changes in the spectral window of 650-950 nm. These contrast agents are often referred to as targeted optical probes. In addition, more sophisticated Systems are increasingly emerging, the optical properties of which can be modulated selectively by Chemical or biological inputs (Elias et al., 2008; Kobayashi et al., 2011; Resch-Genger and Licha, 2011). PY - 2014 SN - 978-0-444-53632-7 DO - https://doi.org/10.1016//B978-0-444-53632-7.00408-1 VL - 4 SP - Chapter 4.02, 15 EP - 26 PB - Elsevier CY - Amsterdam AN - OPUS4-31433 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kage, Daniel A1 - Hoffmann, Katrin A1 - Nifontova, G. A1 - Krivenkov, V. A1 - Sukhanova, A. A1 - Nabiev, I. A1 - Resch-Genger, Ute T1 - Tempo-spectral multiplexing in flow cytometry with lifetime detection using QD-encoded polymer beads N2 - Semiconductor quantum dots (QDs) embedded into polymer microbeads are known to be very attractive emitters for spectral multiplexing and colour encoding. Their luminescence lifetimes or decay kinetics have been, however, rarely exploited as encoding parameter, although they cover time ranges which are not easily accessible with other luminophores. We demonstrate here the potential of QDs made from II/VI semiconductors with luminescence lifetimes of several 10 ns to expand the lifetime range of organic encoding luminophores in multiplexing applications using time-resolved flow cytometry (LT-FCM). For this purpose, two different types of QD-loaded beads were prepared and characterized by photoluminescence measurements on the ensemble level and by single-particle confocal laser scanning microscopy. Subsequently, these lifetime-encoded microbeads were combined with dye-encoded microparticles in systematic studies to demonstrate the potential of these QDs to increase the number of lifetime codes for lifetime multiplexing and combined multiplexing in the time and colour domain (tempo-spectral multiplexing). These studies were done with a recently developed novel luminescence lifetime flow cytometer (LT-FCM setup) operating in the time-domain, that presents an alternative to reports on phase-sensitive lifetime detection in flow cytometry. KW - Fluorescence life time KW - Flow cytometry KW - Lifetime-encoded beads KW - Quantum dots KW - Multiplexing PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-503316 DO - https://doi.org/10.1038/s41598-019-56938-2 VL - 10 IS - 1 SP - Article number: 653 PB - nature.com AN - OPUS4-50331 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hoffmann, Katrin T1 - Fluorescence intensity and quantum yield reference materials for standardization of fluorescence-based measurements N2 - Luminescence techniques are amongst the most commonly used analytical methods in life and material sciences due to their high sensitivity, nondestructive character, and easy instrumentation suitable for miniaturization. Photoluminescence signals are, however, affected by wavelength-, polarization-, and time-dependent instrument-related effects. Thus, at the core of standardization approaches for all fluorescence-based techniques are evaluated fluorescence standards for the consideration of instrument-specific spectral and intensity distortions of measured signals and for instrument performance validation (IPV). Here, we summarize the research of BAM division 1.2 on development of liquid and solid fluorescence standards for various application-relevant fluorescence parameters and techniques. The portfolio of BAM fluorescence reference materials presently consists of: i) a Spectral Fluorescence Standard Kit, i.e., a set of liquid fluorescence standards with certified normalized corrected emission spectra, for the determination of a broad variety of fluorescence parameters ii) a ready-to-use, glass-based multi-emitter fluorescence standard for IPV and the determination of instrument-to-instrument variations iii) specially adapted calibration tools and validation concepts for microarray-based platforms used in molecular diagnostics and food safety control iv) quantum yield (Φf) standards for relative determination of the key performance parameter Φf of fluorescent materials, which can be also used for the evaluation of the performance of absolute, standard-free methods utilizing integrating sphere setups or spectrometer accessories. These materials, that will eventually cover the ultraviolet, visible, and near infrared spectral region, are currently under certification. This toolbox of method-adapted reference materials can perfectly complement existing fluorescence standards. These easy-to-use, reference materials can pave the way to traceable fluorescence measurements to a radiometric scale like the spectral radiance or spectral photon radiance for all users of fluorescence techniques in material sciences and analysis, as well as environmental monitoring and biotechnology. They are particularly useful for customers working in strongly regulated areas like medical diagnostics or pharmaceutical research, where certified standards in conjunction with validated standard operating procedures are mandatory. T2 - International Symposium on Biological and Environmental Reference Materials BERM-15 CY - Berlin, Germany DA - 23.09.2018 KW - Reference materials KW - Fluorescence standards PY - 2018 AN - OPUS4-47140 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Resch-Genger, Ute A1 - Hoffmann, Katrin A1 - Monte, Christian A1 - Pfeifer, Dietmar T1 - Standards in Fluorescence Spectroscopy KW - Standard KW - Fluorescence KW - Reference material KW - Quality assurance KW - Spectrofluorometer PY - 2005 SN - 1434-2634 VL - 9 IS - 6 SP - 29 EP - 31 PB - GIT Verl. CY - Darmstadt AN - OPUS4-11556 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Biesen, L. A1 - Nirmalananthan-Budau, Nithiya A1 - Hoffmann, Katrin A1 - Resch-Genger, Ute A1 - Müller, T. J. J. T1 - Solid-State Emissive Aroyl-S,N-Ketene Acetals with Tunable N2 - N-Benzyl aroyl-S,N-ketene acetals can be readily synthesized by condensation of aroyl chlorides and N-Benzyl 2-methyl benzothiazolium salts in good to excellent yields, yielding a library of 35 chromophores with bright solid-state emission and aggregation-induced emission characteristics. Varying the substituent from electron-donating to electronwithdrawing enables the tuning of the solid-state emission Color from deep blue to red. KW - Nano KW - Nanoparticle KW - Photoluminescence KW - Fluorescence KW - Quantum yield KW - Photophysics KW - Lifetime KW - Sensor KW - dye KW - Enhancement KW - Particle KW - Polarity KW - AIE KW - Aggregation KW - Aggregation-induced emission KW - Solid state emission PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-509072 DO - https://doi.org/10.1002/anie.201916396 VL - 59 IS - 25 SP - 10037 EP - 10041 PB - Wiley Online Libary AN - OPUS4-50907 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Denißen, M. A1 - Nirmalananthan-Budau, Nithiya A1 - Behnke, Thomas A1 - Hoffmann, Katrin A1 - Resch-Genger, Ute A1 - Müller, T. J. J. T1 - 3-Piperazinyl propenylidene indolone merocyanines: consecutive three-component synthesis and electronic properties of solid-state luminophores with AIE properties N2 - A series of twelve 3-piperazinyl propenylidene indolone merocyanines was synthesized in a one-pot fashion using a consecutive three-component insertion-coupling-Michael addition sequence. Physicalorganic treatment of the absorption data of a consanguineous series of this library allows semiquantitative Linear Free Energy Relationships (LFERs) to be established and confirmation of the positive Absorption solvatochromicity. All Boc-substituted piperazinyl merocyanines display aggregation induced Emission (AIE), which was corroborated for two solvent systems. In particular, crystallization-induced Emission enhancement (CIEE) induced by ultrasonication could be shown for a model chromophore by confocal laser scanning microscopy (CLSM). KW - Indolone merocyanines KW - AIE KW - CIEE KW - CLSM PY - 2017 DO - https://doi.org/10.1039/c7qm00198c SN - 2052-1537 N1 - Geburtsname von Nirmalananthan-Budau, Nithiya: Nirmalananthan, N. - Birth name of Nirmalananthan-Budau, Nithiya: Nirmalananthan, N. VL - 1 IS - 10 SP - 2013 EP - 2026 AN - OPUS4-43213 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Engel, A. A1 - Ottermann, C. A1 - Klahn, J. A1 - Korb, T. A1 - Resch-Genger, Ute A1 - Hoffmann, Katrin A1 - Kynast, U. A1 - Rupertus, V. ED - Dan V. Nicolau, ED - Daniel L. Farkas, ED - Robert C. Leif, T1 - Anorganic fluorescence reference materials for decay time of fluorescence emission N2 - Fluorescence techniques are known for their high sensitivity and are widely used as analytical tools, detection methods and imaging applications for product and process control, material sciences, environmental and bio-technical analysis, molecular genetics, cell biology, medical diagnostics, and drug screening. According to DIN/ISO 17025 certified standards are used for steady state fluorescence diagnostics, a method having the drawback of giving relative values for fluorescence intensities only. Therefore reference materials for a quantitative characterization have to be related directly to the materials under investigation. In order to evaluate these figures it is necessary to calculate absolute numbers such as absorption/excitation cross sections and quantum yield. This has been done for different types of dopands in different materials such as glass, glass ceramics, crystals or nano crystalline material embedded in polymer matrices. Samples doped with several fluophores of different emission wavelengths and decay times are required for fluorescent multiplexing applications. Decay times shorter than 100 ns are of special interest. In addition, a proper knowledge is necessary of quantum efficiency in highly scattering media. Recently, quantum efficiency in YAG:Ce glass ceramics has been successfully investigated. Glass and glass ceramics doped with threefold charged rare earth elements are available. However, these samples have the disadvantage of emission decay times much longer than 1 microsecond, due to the excitation and emission of their optical forbidden electronic transitions. Therefore first attempts have been made to produce decay-time standards based on organic and inorganic fluophores. Stable LUMOGEN RED pigments and YAG:Ce phosphors are diluted simultaneously in silicone matrices using a wide range of concentrations between 0.0001 and 2 wt%. Organic LUMOGEN RED has decay times in the lower nanosecond range with a slight dependency on concentration and temperature. In addition, the well-known decay properties of inorganic YAG:Ce are observed also embedded in silicone matrix. Luminescent silicone layers are obtained with thicknesses between 150 and 300 m and no change of decay time, which has been determined to be between 60 and 62 ns. Finally, first results are shown for fluorescent CaF2:Pb glass ceramics embedded in a silicate glass matrix. Wavelength accuracy and lifetime are characterized for different environmental conditions such as temperature treatment and UV irradiation. Moreover, intensity patterns, e.g. line profiles and results, are discussed on homogeneity and photo and thermal stability, respectively. Fluorescence (steady state, decay time) and absorption (remission, absorption) spectroscopy are employed as diagnostic methods to get a microscopic view of the relevant physical processes. The work is funded by BMBF under project number 13N8849. KW - Fluorescence KW - Reference material KW - Glass KW - Glass ceramic KW - Phosphor KW - Doped glass and glass ceramics PY - 2008 SN - 978-0-8194-7034-8 DO - https://doi.org/10.1117/12.767633 VL - 6859 SP - 68591A-1 - 68591A-10 PB - SPIE, the International Society for Optical Engineering CY - Bellingham, Wash. AN - OPUS4-19800 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hoffmann, Katrin A1 - Resch-Genger, Ute A1 - Nitschke, R. T1 - Simple Tool for the Standardization of Confocal Spectral Imaging Systems KW - Standards KW - Fluorescence reference material KW - Quality assurance KW - Fluorescence microscopy PY - 2005 SN - 1439-4243 SN - 1863-7809 VL - 7 IS - 3 SP - 18 EP - 19 PB - GIT-Verl. CY - Darmstadt AN - OPUS4-11070 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Denißen, M. A1 - Hannen, R. A1 - Itskalov, D. A1 - Biesen, L. A1 - Nirmalananthan-Budau, Nithiya A1 - Hoffmann, Katrin A1 - Reiss, G. J. A1 - Resch-Genger, Ute A1 - Müller, T. J. J. T1 - One-pot synthesis of a white-light emissive bichromophore operated by aggregation-induced dual emission (AIDE) and partial energy transfer N2 - Merocyanine–triarylamine bichromophores are readily synthesized by sequentially Pd-catalyzed insertion alkynylation–Michael–Suzuki four-component reactions. White-light emissive systems form upon aggregation in 1 : 99 and 0.1 : 99.9 vol% CH2Cl2–cyclohexane mixtures, ascribed to aggregation-induced dual emission (AIDE) in combination with partial energy transfer between both chromophore units as supported by spectroscopic studies. KW - Energy transfer KW - Nano KW - Nanoparticle KW - Photoluminescence KW - Fluorescence KW - Quantum yield KW - Photophysics KW - Lifetime KW - Sensor KW - Dye KW - Enhancement KW - Particle KW - Polarity KW - AIE KW - Aggregation KW - Aggregation-induced emission KW - Solid state emission KW - Merocyanine PY - 2020 DO - https://doi.org/10.1039/d0cc03451g VL - 56 IS - 54 SP - 7407 PB - Royal Society of Chemistry AN - OPUS4-50936 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kage, Daniel A1 - Fischer, Linn A1 - Hoffmann, Katrin A1 - Thiele, T. A1 - Schedler, U. A1 - Resch-Genger, Ute T1 - Close spectroscopic look at dye-stained polymer microbeads N2 - Dye-stained micrometer-sized polymer beads are important tools in the life sciences with applications in biomedical, biochemical, and clinical research. Here, bead-based assays are increasingly used, for example, in DNA sequencing and the detection of autoimmune diseases or pathogenic microorganisms. Moreover, stained beads are employed as calibration tools for fluorescence microscopy and flow cytometry methods with increasing complexity. To address the requirements concerning the relevant fluorescence features, the spectroscopic properties of representative polymer beads with diameters ranging from about 1 to 10 μm stained with varying concentrations of rhodamine 6G were systematically assessed. The observed dependence of the spectral properties, fluorescence decay kinetics, and fluorescence quantum yields on bead size and dye loading concentration is attributed to different fluorescence characteristics of fluorophores located in the particle core and near-surface dye molecules. Supported by the fluorescence anisotropy measurements, the origin of the observed alteration of fluorescence features is ascribed to a combination of excitation energy transfer and polarity-related effects that are especially pronounced at the interface of the bead and the surrounding medium. The results of our studies underline the need to carefully control and optimize all Parameters that can affect the fluorescence properties of the dye-stained beads. KW - Fluorophore KW - Polymer particles KW - Photophysics KW - Life sciences KW - Standards PY - 2018 DO - https://doi.org/10.1021/acs.jpcc.8b02546 SN - 1932-7447 VL - 122 IS - 24 SP - 12782 EP - 12791 PB - ACS Publications CY - Washington, DC AN - OPUS4-45453 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Biesen, L. A1 - May, L. A1 - Nirmalananthan-Budau, Nithiya A1 - Hoffmann, Katrin A1 - Resch-Genger, Ute A1 - Müller, T. J. J. T1 - Communication of Bichromophore Emission upon Aggregation – Aroyl-S,N-ketene Acetals as Multifunctional Sensor Merocyanines N2 - Aroyl-S,N-ketene acetal-based bichromophores can be readily synthesized in a consecutive three-component synthesis in good to excellent yields by condensation of aroyl chlorides and an N-(p-bromobenzyl) 2-methyl benzothiazolium salt followed by a Suzuki coupling, yielding a library of 31 bichromophoric fluorophores with substitution patterntunable emission properties. Varying both chromophores enables different communication pathways between the chromophores, exploiting aggregation-induced emission (AIE) and energy transfer (ET) properties, and thus, furnishing aggregation-based fluorescence switches. Possible applications range from fluorometric analysis of alcoholic beverages to pH sensors. KW - Dye KW - Fluorescence KW - Aggregation induced emission KW - Signal enhancement KW - Energy transfer KW - Switch KW - Sensor KW - Quantum yield KW - Lifetime KW - Photophysics KW - Synthesis PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-531123 DO - https://doi.org/10.1002/chem.202102052 VL - 27 IS - 53 SP - 13426 EP - 13434 PB - Wiley-VCH AN - OPUS4-53112 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hoffmann, Katrin T1 - Characterization of highly fluorescence candidate glass references standards T2 - 12th Conference on Methods and Applicaions of Fluorescence: Spectroscopy, Imaging and Probes (MAF-12) CY - Strasbourg, France DA - 2011-09-11 PY - 2011 AN - OPUS4-24522 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Hoffmann, Katrin A1 - Resch-Genger, Ute A1 - Nitschke, R. ED - O.S. Wolfbeis, ED - Resch-Genger, Ute T1 - Comparability of fluorescence microscopy data and need for instrument characterization of spectral scanning microscopes N2 - The aim of this article is to illustrate the need for an improved quality assurance in fluorescence microscopy. From the instrument-side, this can be achieved by a better understanding, consideration, and regular control of the instrument-specific parameters and quantities affecting measured fluorescence signals. Particularly, the need for requirements on physical- and chemical-type instrument standards for the characterization and performance validation of spectral fluorescence microscopes (SFMs) is discussed and suitable systems are presented. Special emphasis is given to spectral fluorescence standards and to day-to-day intensity standards for SFMs. Fluorescence standards and well-characterized fluorescence microscopes are the first and essential steps towards the comparability and the understanding of the variability in fluorescence microscopy data in medical and life sciences. In addition, standards enable the distinction between instrument-specific variations and fluorescent label- or probe-related uncertainties as well as generally sample-related effects. KW - Fluorescence spectroscopy KW - Fluorescence microscopy KW - Quality assurance KW - Calibration KW - Standard KW - Comparability KW - Quantification PY - 2008 SN - 978-3-540-70570-3 DO - https://doi.org/10.1007/4243_2008_028 SN - 1617-1306 N1 - Serientitel: Springer Series on Fluorescence – Series title: Springer Series on Fluorescence VL - 6 IS - Part A SP - 89 EP - 116 PB - Springer CY - Berlin, Heidelberg AN - OPUS4-18995 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hoffmann, Katrin T1 - New NIR fluorescence reference materials and quantum yield standards for standardization of fluorescence-based measurements N2 - Luminescence techniques are amongst the most commonly used analytical methods in the life and the material sciences due to their sensitivity and nondestructive character. All photoluminescence signals are, however, affected by wavelength-, polarization- and time-dependent instrument-related effects. Furthermore, substantial challenges to measure absolute luminescence intensities complicate the comparison of data recorded with different instruments and on the same instrument at different times. These problems can be easily resolved with fluorescence standards used for instrument performance validation (IPV) and determination of instrument-to-instrument variations, which allow to measure, quantify, and monitor the wavelength-dependent spectral responsivity for typically used instrument settings. For example, a set of liquid fluorescence standards, the BAM Kit F001-F005, and a ready-to-use glass-based fluorescence standard BAM F-012 developed and certified by BAM enable the characterization of many fluorescence parameters in the UV/vis wavelength range. For the increasingly used near infrared (NIR) region, standards and calibration tools are still very rare. Reliable spectral fluorescence standards and intensity or quantum yield standards are currently not available for the NIR, even though in biology, molecular imaging, and clinical diagnostics fluorescence labels absorbing and emitting in the long wavelength region beyond 650 nm are being increasingly used. This limitation hampers the reliability and comparability of fluorescence measurements in the NIR and calls for simple fluorescence standards for instrument characterization and for the quantification of fluorescence intensities and efficiencies to improve the comparability of the emission measurements in the NIR. This encouraged us to assess the potential of several NIR-emitting materials as spectral fluorescence standards, thereby extending the BAM Kit from the UV/vis into the NIR up to 950 nm. Moreover, we currently certify quantum yield standards for the UV/vis/NIR to improve the reliability of relative measurements of this spectroscopic key quantity particularly > 650 nm. These tools enable an instrument characterization, signal referencing, quality assurance, traceability, and method validation now also for wavelengths > 650 nm, thereby improving the reliability of fluorescence data in pharmaceutical research, medical and clinical diagnostics, material analysis, and environmental monitoring. T2 - 15th Conference on Methods and Applications in Fluorescence (MAF) CY - Brugge, Belgium DA - 10.09.2017 KW - Fluorescence reference materials KW - Quantum yield standard KW - Glass-based fluorescence standard PY - 2017 AN - OPUS4-41990 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hoffmann, Katrin T1 - Reference standards for the performance validation of fluorescence measurement systems T2 - 11th International Conference on Methods and Applications of Fluorescence: Spectroscopy, Imaging and Probes CY - Budapest, Hungary DA - 2009-09-06 PY - 2009 AN - OPUS4-20424 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Behnke, Thomas A1 - Würth, Christian A1 - Hoffmann, Katrin A1 - Hübner, Martin A1 - Panne, Ulrich A1 - Resch-Genger, Ute T1 - Encapsulation of hydrophobic dyes in polystyrene micro- and nanoparticles via swelling procedures N2 - Aiming at the derivation of a generalized procedure for the straightforward preparation of particles fluorescing in the visible and near-infrared (NIR) spectral region, different swelling procedures for the loading of the hydrophobic polarity-probe Nile Red into nano- and micrometer sized polystyrene particles were studied and compared with respect to the optical properties of the resulting particles. The effect of the amount of incorporated dye on the spectroscopic properties of the particles was investigated for differently sized beads with different surface chemistries, i.e., non-functionalized, aminomodified and PEG-grafted surfaces. Moreover, photostability and leaking studies were performed. The main criterion for the optimization of the dye loading procedures was a high and thermally and photochemically stable fluorescence output of the particles for the future application of these systems as fluorescent labels. KW - Fluorescence KW - Nile red KW - Polystyrene KW - Nanoparticles KW - Microparticles KW - Encapsulation KW - Swelling PY - 2011 DO - https://doi.org/10.1007/s10895-010-0632-2 SN - 1053-0509 SN - 1573-4994 VL - 21 IS - 3 SP - 937 EP - 944 PB - Plenum Publ. Corp. CY - New York, NY AN - OPUS4-22692 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -