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 - TY - JOUR A1 - Würth, Christian A1 - Hoffmann, Katrin A1 - Behnke, Thomas A1 - Ohnesorge, Marius A1 - Resch-Genger, Ute T1 - Polymer- and glass-based fluorescence standards for the near infrared (NIR) spectral region N2 - The widespread use and acceptance of fluorescence techniques especially in regulated areas like medical diagnostics is closely linked to standardization concepts that guarantee and improve the comparability and reliability of fluorescence measurements. At the core of such concepts are dependable fluorescence standards that are preferably certified. The ever rising interest in fluorescence measurements in the near-infrared (NIR) spectral region renders the availability of spectral and intensity standards for this wavelength region increasingly important. This encouraged us to develop approaches to solid NIR standards based upon dye-doped polymers and assess their applicationrelevant properties in comparison to metal ion-doped glasses. The overall goal is here to provide inexpensive, easily fabricated, and robust internal and external calibration tools for a broad variety of fluorescence instruments ranging e.g. from spectrofluorometers over fluorescence microscopes to miniaturized fluorescence sensors. KW - Fluorescence standard KW - PMMA KW - Photostability KW - Perylene KW - Rhodamine 800 KW - Dye-doped polymers KW - Glass KW - Laser dye PY - 2011 DO - https://doi.org/10.1007/s10895-010-0650-0 SN - 1053-0509 SN - 1573-4994 VL - 21 IS - 3 SP - 953 EP - 961 PB - Plenum Publ. Corp. CY - New York, NY AN - OPUS4-22184 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Xu, R. A1 - Teich, W. A1 - Frenzel, Florian A1 - Hoffmann, Katrin A1 - Radke, J. A1 - Rösler, J. A1 - Faust, K. A1 - Blank, A. A1 - Brandenburg, S. A1 - Misch, M. A1 - Vajkoczy, P. A1 - Onken, J. S. A1 - Resch-Genger, Ute T1 - Optical characterization of sodium fluorescein in vitro and ex vivo N2 - Objective: The utilization of fluorescein-guided biopsies and resection has been recently discussed as a suitable strategy to improve and expedite operative techniques for the resection of central nervous system (CNS) tumors. However, little is known about the optical properties of sodium fluorescein (NaFl) in human tumor tissue and their potential impact on ex vivo analyses involving fluorescence-based methods. Methods: Tumor tissue was obtained from a study cohort of an observational study on the utilization of fluorescein-guided biopsy and resection (n=5). The optical properties of fluorescein-stained tissue were compared to the optical features of the dye in vitro and in control samples consisting of tumor tissue of high-grade glioma patients (n=3) without intravenous (i.v.) application of NaFl. The dye-exposed tumor tissues were used for optical measurements to confirm the detectability of NaFl emission ex vivo. The tissue samples were fixed in 4%PFA, immersed in 30% sucrose, embedded in Tissue-Tek OCT compound, and cut to 10 mm cryosections. Spatially resolved emission spectra from tumor samples were recorded on representative slides with a Confocal Laser Scanning Microscope FV1000 (Olympus GmbH, Hamburg, Germany) upon excitation with lexc = 488 nm. Results: Optical measurements of fluorescein in 0.9% sodium chloride (NaCl) under in vitro conditions showed an absorption maximum of lmax abs = 479 nm as detected with spectrophotometer Specord 200 and an emission peak at lmax em = 538 nm recorded with the emCCD detection system of a custom-made microscope-based single particle setup using a 500 nm long-pass filter. Further measurements revealed pH- and concentration-dependent emission spectra of NaFl. Under ex vivo conditions, confocal laser scanning microscopy of fluorescein tumor samples revealed a slight bathochromic shift and a broadening of the emission band. Conclusion: Tumor uptake of NaFl leads to changes in the optical properties – a bathochromic shift and broadening of the emission band – possibly caused by the dye’s high pH sensitivity and concentration-dependent reabsorption acting as an innerfilter of the dye’s emission, particularly in the short wavelength region of the Emission spectrum where absorption and fluorescence overlap. Understanding the ex vivo optical properties of fluorescein is crucial for testing and validating its further applicability as an optical probe for intravital microscopy, immunofluorescence localization studies, and flow cytometry analysis. KW - Fluorescence KW - Optical probe KW - Sensor KW - Fluorescein KW - PH KW - Imaging KW - Tissue KW - Cancer KW - Medical diagnostics KW - Tumor KW - In vivo KW - Ex vivo KW - Quantum yield KW - Dye KW - Quality assurance KW - Microscopy PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-527843 DO - https://doi.org/10.3389/fonc.2021.654300 SN - 2234-943X VL - 11 SP - 1 EP - 8 PB - Frontiers Media CY - Lausanne AN - OPUS4-52784 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Friedrich, Jörg Florian A1 - Kühn, Gerhard A1 - Mix, Renate A1 - Hoffmann, Katrin A1 - Resch-Genger, Ute T1 - Tailoring of polymer surfaces with monotype functional groups of variable density using chemical and plasma chemical processes N2 - Polymer surfaces were modified in low-pressure glow discharge plasmas for introduction of monotype functional groups of different type and density. For this purpose three ways are selected, (i) oxygen plasma treatment followed by wet-chemical reduction of O functional groups to OH groups, (ii) plasma bromination for introducing C - Br groups and (iii) coating by deposition of thin plasma (co-) polymerized layers of functional groups-bearing monomers with OH, NH2, COOH, epoxy etc. functionalities. Subsequently, these groups were used as anchoring points for chemical grafting of spacer molecules, oligomers, prepolymers, fluorescent labels, ionic and nucleic acid residues, employing different chemical routes. The yield in monosort functional groups at polymer surfaces ranged from 10–14 (process i), 20–40 (process ii) and 18–31 groups per 100 C atoms (process iii) as measured by XPS after derivatization. The consumption of functional groups amounted to 40–90% of all functionalities present at the surface and depended on the dimensions of grafted molecules. For infinitely variably tuning the number of functional groups process iii was performed as copolymerization of a functional group-carrying comonomer with a non-functionalized (“chain-extending”) comonomer. KW - Introduction of functional groups KW - Plasma modification KW - Reactions at Polymer surfaces PY - 2006 SN - 0340-255x SN - 1437-8027 VL - 132 SP - 62 EP - 71 PB - Springer CY - Berlin AN - OPUS4-12515 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hoffmann, Katrin T1 - Reference Standard for the performance validation of fluroescence measuring systems T2 - Life Science Day 2011 CY - Berlin, Germany DA - 2011-08-26 PY - 2011 AN - OPUS4-24520 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kage, Daniel A1 - Hoffmann, Katrin A1 - Borcherding, H. A1 - Schedler, U. A1 - Resch-Genger, Ute T1 - Lifetime encoding in flow cytometry for bead‑based sensing of biomolecular interaction N2 - To demonstrate the potential of time-resolved flow cytometry (FCM) for bioanalysis, clinical diagnostics, and optically encoded bead-based assays, we performed a proof-of-principle study to detect biomolecular interactions utilizing fluorescence lifetime (LT)-encoded micron-sized polymer beads bearing target-specific bioligands and a recently developed prototype lifetime flow cytometer (LT-FCM setup). This instrument is equipped with a single excitation light source and different fluorescence detectors, one operated in the photon-counting mode for time-resolved measurements of fluorescence decays and three detectors for conventional intensity measurements in different spectral windows. First, discrimination of bead-bound biomolecules was demonstrated in the time domain exemplarily for two targets, Streptavidin (SAv) and the tumor marker human chorionic gonadotropin (HCG). In a second step, the determination of biomolecule concentration levels was addressed representatively for the inflammation-related biomarker tumor necrosis factor (TNF-α) utilizing fluorescence intensity measurements in a second channel of the LT-FCM instrument. Our results underline the applicability of LT-FCM in the time domain for measurements of biomolecular interactions in suspension assays. In the future, the combination of spectral and LT encoding and multiplexing and the expansion of the time scale from the lower nanosecond range to the longer nanosecond and the microsecond region is expected to provide many distinguishable codes. This enables an increasing degree of multiplexing which could be attractive for high throughput screening applications. KW - Fluorescence KW - Sensor KW - Assay KW - Protein KW - Multiplexing KW - Flow cytometry KW - Barcoding KW - Lifetime KW - Dye KW - Bead KW - Bead-based assay KW - Method KW - Quantification PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-516007 DO - https://doi.org/10.1038/s41598-020-76150-x VL - 10 IS - 1 SP - 19477 PB - Nature AN - OPUS4-51600 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hoffmann, Katrin A1 - Nirmalananthan-Budau, Nithiya A1 - Resch-Genger, Ute T1 - Fluorescence calibration standards made from broadband emitters encapsulated in polymer beads for fluorescence microscopy and flow cytometry N2 - We present here the design and characterization of a set of spectral calibration beads. These calibration beads are intended for the determination and regular control of the spectral characteristics of fluorescence microscopes and other fluorescence measuring devices for the readout of bead-based assays. This set consists of micrometer-sized polymer beads loaded with dyes from the liquid Calibration Kit Spectral Fluorescence Standards developed and certified by BAM for the wavelength-dependent Determination of the spectral responsivity of fluorescencemeasuring devices like spectrofluorometers. To cover the wavelength Region from 400 to 800 nm, two new near-infrared emissive dyes were included, which were spectroscopically characterized in solution and encapsulated in the beads. The resulting set of beads presents the first step towards a new platform of spectral calibration beads for the determination of the spectral characteristics of fluorescence instruments like fluorescence microscopes, FCM setups, and microtiter plate readers, thereby meeting the increasing demand for reliable and comparable fluorescence data especially in strongly regulated areas, e.g., medical diagnostics. This will eventually provide the basis for standardized calibration procedures for imaging systems as an alternative to microchannel slides containing dye solutions previously reported by us. KW - Fluorescence standard KW - Fluorescence KW - Dye KW - Microscopy KW - Bead KW - Particle KW - NIR KW - calibration KW - Quality assurance KW - Traceability PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-508117 DO - https://doi.org/10.1007/s00216-020-02664-y SN - 1618-2642 VL - 412 IS - 24 SP - 6499 EP - 6507 PB - Springer AN - OPUS4-50811 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hoffmann, Katrin T1 - On the Spectral Sensitivity Calibration of Fluorescence Spectrometers: Extensions to the NIR, Polarization and Grating Effects T2 - 12th Conference on Methods and Applications of Fluorescence: Spectroscopy, Imaging and Probes (MAF-12) CY - Strasbourg, France DA - 2011-09-11 PY - 2011 AN - OPUS4-24521 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pauli, Jutta A1 - Hoffmann, Katrin A1 - Würth, Christian A1 - Behnke, Thomas A1 - Resch-Genger, Ute T1 - Standardization of fluorescence measurements in the UV/vis/NIR/IR N2 - Photoluminescence techniques are amongst the most widely used Tools in the life sciences, with new and exciting applications in medical diagnostics and molecular Imaging continuously emerging. Advantages include their comparative ease of use, unique sensitivity, non-invasive character, and potential for Multiplexing, remote sensing, and miniaturization. General drawbacks are, however, signals, that contain unwanted wavelength- and polarization contributions from Instrument-dependent effects, which are also time-dependent due to aging of Instrument-components, and difficulties to measure absolute flourescence entensities. Moreover, scattering Systems require Special measurement geometries and the interest in new optical Reporters with Emission > 1000 nm strategies for reliable measurements in the second diagnostic for the comparison of material Performance and the rational designg of new flourophores with improved properties. Here, we present strategies to versatile method-adaptable liquid and solid flourescence Standards for different flourescence paramters including traceable Instrument calibration procedures and the design of integrating spere setups for the absolute measurements of emission spectra and Quantum yields in the wavelength Region of 350 to 1600 nm. Examples are multi-Emitter glasses, spectral flourescence Standards, and quantum yield Standards for the UV/vis/NIR. T2 - Conference on Molecular-Guided Surgery - Molecules, Devices, and Applications III CY - San Francisco, CA, USA DA - 28.01.2017 KW - Fluorescence KW - Reference material KW - Standard KW - Calibration KW - Nanoparticle KW - Absolute flourometry KW - Integrating sphere spectroscopy KW - NIR KW - IR KW - Quantum yield standard KW - Emission standards PY - 2017 SN - 978-1-5106-0539-8 DO - https://doi.org/10.1117/12.2255728 SN - 0277-786X VL - 10049 SP - 1 PB - Proceedings of SPIE AN - OPUS4-41783 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hoffmann, Katrin T1 - Absorption and Fluorescence Properties of Dyes Incorporated in Pores of AlPO4-5 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 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 - JOUR A1 - Felbeck, Tom A1 - Hoffmann, Katrin A1 - Resch-Genger, Ute A1 - Lezhnina, M.M. A1 - Kynast, U.H. T1 - Fluorescent nanoclays: Covalent functionalization with amine reactive dyes from different fluorophone classes and surface group quantification N2 - The ever increasing applications of fluorescence techniques in conjunction with the interest in enhanced detection sensitivities in bioanalysis, biosensing, and bioimaging are closely linked to the rational design of novel nontoxic fluorescent nanomaterials with improved brightness and stability that can be reproducibly synthesized from inexpensive starting materials in simple one-pot reactions and easily surface functionalized. This encouraged us to investigate the potential of the commercially available water-dispersible nanoclay Laponite RD with the empirical formula Na0.7(H2O)n{(Li0.3Mg5.5)[Si8O20(OH)4]}, forming 25 nm sized disk-shaped particles, as nanocarriers for different fluorophores. The Si–OH functions at the rims of these disks can be selectively grafted with 3-aminopropyldimethylethoxysilane (APES), thereby enabling subsequent coupling to amine-reactive molecules ranging from target-specific organic ligands and biomolecules to amine-reactive fluorescent labels. Here, we present different strategies for the surface functionalization of nanoclays and the subsequent quantification of the density of synthetically introduced surface amino groups exploiting analytical methods which rely on different detection schemes including elemental analysis, colorimetric assays, and fluorophore labeling strategies. In this respect, we systematically assess the potential of negatively and positively charged, neutral, and zwitterionic dyes to act as fluorescent labels for amino functionalities at the surface of negatively charged nanoclays. Our studies underline the strong influence of dye charge and aggregation tendency on the brightness of the bound dyes and on surface group quantification. Best results regarding surface group analysis and coupling yield were obtained for a neutral dansyl derivative and fluorescamine. PY - 2015 DO - https://doi.org/10.1021/acs.jpcc.5b01482 SN - 1932-7447 SN - 1089-5639 VL - 119 IS - 23 SP - 12978 EP - 12987 PB - Soc. CY - Washington, DC AN - OPUS4-33614 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 - GEN A1 - Hoffmann, Katrin A1 - Mix, Renate A1 - Friedrich, Jörg Florian A1 - Resch-Genger, Ute ED - Geddes, C.D. T1 - Spectroscopic characterization of plasma - Chemically functionalized and fluorophore-labeled polymer surfaces N2 - The potential of spectrofluorometry and fluorescence microscopy for the characterization and quantification of different functionalities like OH and NH2 groups at plasma-chemically modified polymer surfaces is assessed using traditional reactive dyes such as dansyl derivatives and a sophisticated VIS-excitable chromogenic and fluorogenic pyrylium label showing binding-induced spectral and intensity changes in absorption and emission. Aiming at an improved fluorometric surface analysis, based upon these measurements, several sources of uncertainty inherent to fluorescence measurements are illustrated ranging from environment-dependent dye absorption and emission features over spectral correction and nonspecific adsorption to the critical influence of label choice on the measured background. Solutions to these drawbacks are given thereby underlining the potential of fluorometry for surface analysis. KW - Polymer functionalization KW - Plasma modification KW - Fluorescence spectroscopy KW - Surface labeling PY - 2010 SN - 978-1-4419-0828-5 DO - https://doi.org/10.1007/978-1-4419-1260-2_6 N1 - Serientitel: Reviews in Fluorescence – Series title: Reviews in Fluorescence VL - 5 SP - 139 EP - 160 PB - Springer Science + Business Media AN - OPUS4-21274 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hoffmann, Katrin T1 - Reversible photosensitive refractive index changes of chromophore/zeolite nanocomposites T2 - Abschlusskolloquium des DFG-Schwerpunktprogramms "Nanoporöse Kristalle" CY - Berlin, Germany DA - 2002-10-21 PY - 2002 AN - OPUS4-10907 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Resch-Genger, Ute A1 - Hoffmann, Katrin A1 - Nietfeld, W. A1 - Engel, A. A1 - Neukammer, J. A1 - Nitschke, R. A1 - Ebert, B. A1 - Macdonald, R. T1 - How to Improve Quality Assurance in Fluorometry: Fluorescence-Inherent Sources of Error and Suited Fluorescence Standards N2 - The scope of this paper is to illustrate the need for an improved quality assurance in fluorometry. For this purpose, instrumental sources of error and their influences on the reliability and comparability of fluorescence data are highlighted for frequently used photoluminescence techniques ranging from conventional macro- and microfluorometry over fluorescence microscopy and flow cytometry to microarray technology as well as in vivo fluorescence imaging. Particularly, the need for and requirements on fluorescence standards for the characterization and performance validation of fluorescence instruments, to enhance the comparability of fluorescence data, and to enable quantitative fluorescence analysis are discussed. Special emphasis is dedicated to spectral fluorescence standards and fluorescence intensity standards. KW - Fluorescence KW - Standard KW - Calibration KW - Microarray KW - In vivo imaging KW - Flow cytometry PY - 2005 DO - https://doi.org/10.1007/s10895-005-2630-3 SN - 1053-0509 SN - 1573-4994 VL - 15 IS - 3 SP - 337 EP - 362 PB - Plenum Publ. Corp. CY - New York, NY AN - OPUS4-10823 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hoffmann, Katrin T1 - Fast and Reliable Luminescence Quantum Yield Determination for efficient fluorescent Probes development 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 T1 - Nanoparticles for FLIM-based Multiplexed Analysis and Imaging T2 - Focus on Microscopy (FOM 2013) CY - Maastricht, Netherlands DA - 2013-03-24 PY - 2013 AN - OPUS4-28470 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hoffmann, Katrin T1 - FLIM Imaging and Lifetime-Based Multiplexed Analysis with NIR-Fluorescent Nanoparticles T2 - 13. Conference on Methods and Applications Flourescence CY - Genoa, Italy DA - 2013-09-08 PY - 2013 AN - OPUS4-29228 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mix, Renate A1 - Hoffmann, Katrin A1 - Buschmann, H.-J. A1 - Friedrich, Jörg Florian A1 - Resch-Genger, Ute T1 - Anbindung von Fluoreszenzfarbstoffen an plasmachemisch funktionalisierte und Cucurbituril-modifizierte Oberflächen N2 - Plasmapolymerisierte Allylaminschichten (50 nm) wurden auf Polypropylenfolien abgeschieden. Die auf diese Weise generierte NH2-funktionalisierte Polymeroberfläche wurde mit Xanthen-Fluorophoren chemisch umgesetzt. Da die Farbstoff-gekoppelten Folien nur geringe Fluoreszenz aufwiesen, wurden zwei Wege zur möglichen Entkopplung der Farbstoffe von der Oberfläche und damit zur Erhöhung der Fluoreszenzintensität getestet. Als erstes wurde ein Spacer durch die Umsetzung der primären Aminogruppen mit Glutaraldehyd und der nachfolgenden Kettenverlängerung mit Diaminohexan eingeführt. Diese nachfolgende Reaktion ergab eine spacergebundene NH2-Oberfläche, die analog der Allylaminschicht mit den Farbstoffen umgesetzt wurde. Als weiterer Weg wurde der Zusatz einer geeigneten Käfigverbindung, des Cucurbit[6]urils, getestet. Die spacergebundenen und zusätzlich mit Cucurbituril modifizierten aminofunktionellen Oberflächen zeigten nach der Farbstoffankopplung eine verbesserte Fluoreszenzintensität. KW - Fluoreszenz KW - Spacer KW - Cucurbituril PY - 2007 DO - https://doi.org/10.1002/vipr.200700329 SN - 0947-076X SN - 1522-2454 VL - 19 IS - 5 SP - 31 EP - 37 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-16000 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hoffmann, Katrin T1 - NanoGenotox - Automatable determination of genotoxicity of nanoparticles with DNA-based optical assays N2 - The overall interest in nanotoxicity, triggered by the increasing use of nanomaterials in the material and life sciences, and the synthesis of an ever increasing number of new functional nanoparticles calls for standardized test procedures and for efficient approaches to screen the potential genotoxicity of these materials. Aiming at the development of fast and easy to use, automated microscopic methods for the determination of the genotoxicity of different types of nanoparticles, we assess the potential of the fluorometric γH2AX assay for this purpose. This assay, which can be run on an automated microscopic detection system, relies on the detection of DNA double strand breaks (DSB) as a sign for genotoxicity. Here, we provide first results obtained with broadly used nanomaterials like CdSe/CdS and InP/ZnS quantum dots as well as iron oxide, gold, and polymer particles of different surface chemistry with previously tested colloidal stability and different cell lines like Hep-2 and 8E11 cells, which reveal a dependence of the genotoxicity on the chemical composition as well as the surface chemistry of these nanomaterials. These studies will be also used to establish nanomaterials as positive and negative genotoxicity controls or standards for assay performance validation for users of this fluorometric genotoxicity assay. In the future, after proper validation, this microscopic platform technology will be expanded to other typical toxicity assays. T2 - Nanoworkshop 2018 CY - PTB Berlin-Adlershof, Germany DA - 14.05.2018 KW - Qdots KW - Surface functions KW - Quantification KW - Nanogenotoxicity PY - 2018 AN - OPUS4-45126 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -