TY - CONF A1 - Hoffmann, Katrin A1 - Rurack, Knut A1 - Resch-Genger, Ute A1 - Marlow, Frank T1 - Absorption and Fluorescence Properties of Dyes Incorporated in Pores of AlPO4-5 T2 - 14. Deutsche Zeolith-Tagung T2 - 14. Deutsche Zeolith-Tagung CY - Frankfurt am Main, Germany DA - 2002-03-06 PY - 2002 AN - OPUS4-3261 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hoffmann, Katrin A1 - Nirmalananthan-Budau, Nithiya A1 - Wegmann, M. A1 - Resch-Genger, Ute T1 - Calibration Beads for the Characterization of the Performance of Fluorescence-based High- Throughput and Imaging devices N2 - In all fluorescence-based techniques, the measured signals contain not only sample-related but also instrument-specific contributions, which limit the direct comparison of fluorescence data obtained e.g. on different devices or at different times and often hamper quantification. To rule out instrumentation as major source of variability of emission data, accepted fluorescence standards and procedures for the control of instrument specifications and long-term performance are required. For flow cytometry (FCM), a broad variety of fluorophore-stained polymer beads differing in emission wavelength and intensity is available for the testing of the alignment, sensitivity, and other parameters of FCM. These calibration tools are intended to facilitate the assessment of instrument performance to ensure reliable measurements and to improve the comparability of FCM experiments. As a step towards an improved comparability of fluorescence data, with special emphasis on spectroscopic methods measuring nano- and micrometer-sized fluorescent objects, we are currently developing a set of fluorescent polystyrene (PS) beads loaded with luminophores from the certified BAM-Kit “Spectral fluorescent standards”, initially developed for the calibration of fluorescence spectrometers. Here, we present first results from studies of these fluorophore-loaded polymer beads. Moreover, new beads are made to supplement this kit by encapsulating near-infrared (NIR)-emissive luminophores in PS beads to cover the UV/VIS, and NIR wavelength range. These beads are designed for calibration of flow cytometers and other fluorescence imaging systems to meet the increasing demand for reliable and comparable fluorescence data especially in strongly regulated areas like e.g. medical diagnostics. T2 - 29th Annual Conference of the German Society for Cytometry CY - Berlin, Germany DA - 25.09.2019 KW - Calibration beads KW - Fluorescence KW - Performance validation KW - imaging KW - FCM PY - 2019 AN - OPUS4-49422 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hoffmann, Katrin A1 - Engel, A. A1 - Bäumle, M. A1 - Resch-Genger, Ute T1 - Characterization of highly fluorescence candidate glass references standards T2 - 12th Conference on Methods and Applicaions of Fluorescence: Spectroscopy, Imaging and Probes (MAF-12) 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 - CONF A1 - Hoffmann, Katrin A1 - Resch-Genger, Ute A1 - Mix, Renate A1 - Friedrich, Jörg F. A1 - Nitschke, R. T1 - Characterization of Surface Functionalities of Plasma-modified Polymer Films by Fluorescence Spectroscopy and Microscopy T2 - ANAKON 2005 T2 - ANAKON 2005 CY - Regensburg, Germany DA - 2005-03-15 PY - 2005 AN - OPUS4-7390 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hoffmann, Katrin A1 - Abbandonato, Gerardo A1 - Resch-Genger, Ute T1 - Determination of Photoluminescence Quantum Yields of Semiconductor Quantum Dots with Fluorescence Correlation Spectroscopy N2 - There is an increasing interest in bridging the gap between the photoluminescence (PL) properties of nanomaterials like semiconductor nanocrystals (QDs) commonly assessed in ensemble studies and the PL features of single QDs for life sciences applications such as bioimaging studies or use in microfluidic assays. The fluorescence quantum yield (ΦF) is a key performance parameter for all molecular and nanoscale emitters, increasingly employed in nanoscience, nanotechnology, and medical diagnostics. ΦF determines not only the signal size together with the reporter´s molar extinction coefficient, yet it is particularly relevant for nanocrystals like QDs with coordinatively bound surface ligands and size- and surface chemistry-dependent PL characteristics. The importance of ΦF measurements at ultralow concentration encouraged us to explore the potential of fluorescence correlation spectroscopy (FCS) for the relative determination of ΦF of ligand-stabilized CdTe nanocrystals in comparison to molecular dyes with closely matching spectral properties and known ΦF. We describe a FCS-based method for the relative determination of ΦF of dispersed QDs at ultralow concentrations, and procedures to overcome QD-inherent challenges like complex and power-dependent blinking behavior as well as ligand- and QD-specific aggregation. We could demonstrate the potential of this approach by comparison with steady state ensemble measurements. T2 - BIOS SPIE 2019 CY - San Francisco, CA, USA DA - 02.02.2019 KW - Quantum yield KW - Quantum dots KW - FCM PY - 2019 AN - OPUS4-47427 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hoffmann, Katrin A1 - Sewohl, Dirk A1 - Resch-Genger, Ute T1 - Evaluation of Lanthanide-doped Glasses for Use as standards in Fluorometry T2 - First International Conference on Luminescence of Lanthanides T2 - First International Conference on Luminescence of Lanthanides CY - Odessa, Ukraine DA - 2010-09-05 PY - 2010 AN - OPUS4-21566 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hoffmann, Katrin A1 - Resch-Genger, Ute A1 - Würth, Christian A1 - Koberling, F. A1 - Rüttinger, S. A1 - Tannert, S. A1 - Erdmann, R. T1 - Fast and Reliable Luminescence Quantum Yield Determination for efficient fluorescent Probes development T2 - SPIE BIOS 2013 - Part of Photonics West T2 - SPIE BIOS 2013 - Part of Photonics West CY - San Francisco, CA, USA DA - 2013-02-02 PY - 2013 AN - OPUS4-27804 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hoffmann, Katrin A1 - Pauli, Jutta A1 - Resch-Genger, Ute 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 - CONF A1 - Hoffmann, Katrin A1 - Tschiche, Harald Rune A1 - Resch-Genger, Ute T1 - Fluorescence microscopic and spectroscopic monitoring of degradation processes upon polymer ageing N2 - The majority of all routinely used methods to assess polymer aging are based on destructive tests and methods. Early indicators for the deterioration of polymer materials are e.g., physical or mechanical properties like tensile strength, adhesion, brittleness, and color. It is well-known, however, that predominantly chemical changes are the underlying process of the physical changes that occur in organic materials upon aging over time. Typical initial steps during polymer degradation are crosslinking or chain breaking, alteration of autofluorescence, “yellowing” or bleaching caused by the formation of new functional groups. A straightforward strategy towards the sensitive detection and monitoring of chemical changes in the course of polymer aging is based on non-destructive optical measurements. Luminescence techniques, one of the most sensitive spectroscopic methods are the method of choice. Here, we present first results of luminescence-based monitoring of polymer degradation induced by different environmentally relevant weathering factors (e.g. humidity and UV exposure). Our studies include fluorescence spectroscopy as well as spectral scanning confocal fluorescence microscopy and clearly demonstrate the possibility to follow accelerate-aging processes by luminescence detection. T2 - Focus on Microscopy 2017 CY - Bordeaux, France DA - 09.04.2017 KW - Polymer aging KW - Confocal fluorescence microscopy KW - Fluorescence spectroscopy KW - Surface functionalities PY - 2017 AN - OPUS4-40274 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hoffmann, Katrin A1 - Resch-Genger, Ute A1 - Mix, Renate A1 - Friedrich, Jörg F. A1 - Nitschke, R. T1 - Fluorescence microscopic and spetroscopic studies on functionalized polymer-supports labeled with amino sensitive fluorophores T2 - Focus on Microscopy (FoM) 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 -