TY - CONF A1 - Radunz, Sebastian T1 - Simple approach to pKa tunable BOIDPY-based fluorescent pH sensors N2 - Successfull synthesis of pH-responsive fluorescence ON/OFF sensor dyes with tunable pK values covering the pH range of 5 to 12 Immobilizing of multiple dyes with different pK values into a polymer host matrix provides a pH sensor with a dynamic range. T2 - First European/ 10th German BioSensor Symposium CY - Potsdam, Germany DA - 20.03.2017 KW - Fluorescence KW - Sensing KW - pH PY - 2017 AN - OPUS4-39683 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fidan, Z. A1 - Wende, A. A1 - Resch-Genger, Ute T1 - Visible and red emissive molecular beacons for optical temperature measurements and quality control in diagnostic assays utilizing temperature-dependent amplification reactions N2 - Quality control requirements imposed on assays used in clinical diagnostics and point-of-care-diagnostic testing (POCT), utilizing amplification reactions performed at elevated temperatures of 35 to 95 °C are very stringent. As the temperature of a reaction vessel has a large impact on the specificity and sensitivity of the amplification reaction, simple tools for local in situ temperature sensing and monitoring are required for reaction and assay control. We describe here a platform of stem-and-loop structured DNA hairpins (molecular beacons, MBs), absorbing and emitting in the visible and red spectral region, rationally designed for precise temperature measurements in microfluidic assays for POCT, and their ap-plication for temperature measurements in a common DNA-based molecular biological assay utilizing thermophilic helicase-dependent amplification (tHDA). Spectroscopic studies of these MBs, rationally designed from DNA se-quences of different thermal stabilities, chosen not to interact with the DNA probes applied in the nucleic acid amplification assay, and temperature-dependent fluorescence measurements of MB-assay mixtures revealed the suitability of these MBs for temperature measurements directly in such an assay with a temperature resolution of about 0.5 °C without interferences from assay components. Combining two spectrally distinguishable MBs provides a broader response range and an increase in temperature sensitivity up to 0.1 °C. This approach will find future application for temperature monitoring and quality control in commercialized diagnostics assays using dried reagents and microfluidic chips as well as assays read out with tube and microplate readers and PCR detection systems for temperature measurements in the range of 35 to 95 °C. KW - Miniaturization KW - Fluorescence KW - Temperature KW - Sensor KW - Assay KW - Microfluidics KW - DNA KW - Dye KW - Molecular beacon KW - Molecular diagnostics PY - 2016 DO - https://doi.org/10.1007/s00216-016-0088-6 SN - 1618-2642 VL - 409 IS - 6 SP - 1519 EP - 1529 PB - Springer CY - Heidelberg AN - OPUS4-39589 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kage, Daniel T1 - Luminophores for time-resolved flow cytometry N2 - For the application of time-resolved detection in the framework of flow cytometry, suitable luminescence lifetime code carriers are required. Here we report on our achievements concerning strategies to increase the accessible range of lifetime values and to realize continuously tunable lifetimes. To that end, we investigated polymer (PMMA) microbeads stained with mixtures of dyes exhibiting different fluorescence decay kinetics. At the expense of spectrally varying decay kinetics, it is possible to modify the lifetime by changing the dye concentration ratio. Moreover, semiconductor quantum dots incorporated into polymer beads were studied as alternative luminophores outperforming organic dyes with respect to long luminescence lifetimes, flexible choice of excitation wavelength and narrow spectral emission width. Our experiments demonstrate that lifetime adaption with dye mixing is basically feasible and semiconductor quantum dots represent promising candidates for long-lifetime codes. T2 - FLiMFlow meeting CY - Münster, Germany DA - 03.03.2017 KW - Flow cytometry KW - Fluorescence KW - Life sciences KW - Lifetime encoding KW - Polymer particles PY - 2017 AN - OPUS4-39307 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute T1 - Spectroscopic properties of upconversion nanoparticles N2 - Lanthanide-doped up-converting nanoparticles (UCNPs) are promising reporters for medical diagnostics and bioimaging. Current limitations present their relative low absorption cross sections and low fluorescence efficiencies, with the latter being affected by particle size, surface chemistry, and microenvironment, particularly water. Here, we present results from systematic studies of the excitation power density dependent upconversion luminescence spectra, intensities/intensity ratios of the individual emission bands, slope factors, and quantum yields of UCNPs of varying size, dopant concentration, and surface chemistry in different microenvironments as well as the up- and downconversion luminescence decay kinetics of the different emission bands. Moreover, first studies of the energy transfer from UCNPs to surface-bound organic dyes acting as fluorescence acceptors are shown. Based upon these measurements, fluorescence deactivation channels are identified and spectroscopic parameters for the screening of material performance are derived. T2 - Projekttreffen COST CY - Straßbourg, France DA - 09.01.2017 KW - Upconverting nanoparticles KW - Size KW - FRET KW - Fluorescence KW - Absolute fluorescence quantum yield KW - Fluorescence decay kinetics KW - Power density dependence PY - 2017 AN - OPUS4-39076 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute T1 - Recent insights in the spectroscopic properties of upconversion nanoparticles N2 - Lanthanide-doped up-converting nanoparticles (UCNPs) are promising reporters for medical diagnostics and bioimaging, which are excited in the near infrared (NIR) by multiphoton absorption processes, and show multiple narrow emission bands in the visible (vis) and NIR, long luminescence lifetimes in the μs range, and excellent photostability. Current limitations present their relative low absorption cross sections and low fluorescence efficiencies, with the latter being affected by particle size, surface chemistry, and microenvironment, particularly water. Here, we present results from systematic studies of the excitation power density dependent upconversion luminescence spectra, intensities/intensity ratios of the individual emission bands, slope factors, and quantum yields of UCNPs of varying size, dopant concentration, and surface chemistry in different microenvironments as well as the up- and downconversion luminescence decay kinetics of the different emission bands. Moreover, first studies of the energy transfer from UCNPs to surface-bound organic dyes acting as fluorescence acceptors are shown. Based upon these measurements, fluorescence deactivation channels are identified and spectroscopic parameters for the screening of material performance are derived. T2 - Spie Photonics west 2017 CY - San Francisco, USA DA - 28.01.2017 KW - Upconverting nanoparticles KW - Size KW - FRET KW - Fluorescence KW - Absolute fluorescence quantum yield KW - Fluorescence decay kinetics KW - Power density dependence PY - 2017 AN - OPUS4-39075 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ramirez Caro, Alejandra A1 - Pauli, Jutta A1 - Schmidt, Wolfram A1 - Resch-Genger, Ute T1 - Study of the superplasticizer-cement hydration interaction by optical spectroscopy N2 - Nowadays, superplasticizers (SPs) are widely used to increase fluidity and reduce water content in concrete; thus, allowing better workability for final applications. The present study will focus on the hydration effect using comb shape polycarboxylates (PCEs), which are known to allow a very low water/cement ratio (w/c of 0.20) or less.Optical methods have been successfully used for the analysis and monitoring of the interactions between a broad variety of nanoscale and molecular systems like nanoparticles of various chemical composition and different types of organic ligands or biomolecules.This encouraged us to assess the potential of these methods, and particularly fluorescence, for the investigation of the interactions that occur at the interface between hydrate surfaces of cement particles and PCE at a very early stage of concrete formation and to differentiate between the impact of PCE’s molecular structures on such interactions. T2 - 2nd International Conference on the Chemistry of Construction Materials CY - Munich, Germany DA - 10.10.2016 KW - Cement KW - Dye KW - Superplasticizers KW - Fluorescence PY - 2016 SN - 978-3-936028-96-6 VL - 50 SP - 260 EP - 263 PB - Gesellschaft Deutscher Chemiker e.V. CY - Frankfurth am Main AN - OPUS4-38881 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hoffmann, Katrin T1 - Reference Materials for Standardization of Fluorescence-based Measurements N2 - Here, we summerize our efforts concerning new design concepts and examples for fluorescence standards that can provide traceability to radiometric units and present a first step towards a toolbox of fluorescence standards, currently consisting of: i) A first set of liquid fluorescence standards enables the determination of a broad variety of fluorescence parameters was developed and certified by BAM and is distributed by Sigma-Aldrich. ii) Ready-to-use, glass-based fluorescence standards for instrument performance validation (IPV) and determination instrument-to-instrument variations can also be used as wavelength standard for fluorescence instruments with low requirements on spectral resolution and allow monitoring of temporal changes of the wavelength-dependent spectral responsivity. iii) Novel calibration tools and validation concepts for microarray-based platforms used in molecular diagnostics and food safety control. iv) We currently develop reference materials, which can be used as reliable quantum yield standards for relative methods for the determination of QY and can be valuable in the evaluation of the performance and sources of uncertainty of absolute, standard-free methods using e.g. integrating spheres. T2 - 14th Conference on Methods and Applications in Fluorescence CY - Würzburg, Germany DA - 13.09.2015 KW - Fluorescence KW - Standards KW - Quantum yield KW - Microarray PY - 2015 AN - OPUS4-38882 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pauli, Jutta A1 - Wycisk, V. A1 - Welker, P. A1 - Justies, A. A1 - Resch-Genger, Ute A1 - Haag, R. A1 - Licha, K. T1 - Glycerol-Based Contrast Agents: A Novel Series of Dendronized Pentamethine Dyes N2 - The synthesis of water-soluble dyes, which absorb and emit in the range between 650 and 950 nm and display high extinction coefficients (ε) as well as high fluorescence quantum yields (Φf), is still a demand for optical imaging. We now present a synthetic route for the preparation of a new group of glycerol-substituted cyanine dyes from dendronized indole precursors that have been functionalized as Nhydroxysuccinimide (NHS) esters. High Φf values of up to 0.15 and extinction coefficients of up to 189 000 L mol−1 cm−1 were obtained for the pure dyes. Furthermore, conjugates of the new dendronized dyes with the antibody cetuximab (ctx) that were directed against the epidermal growth factor receptor (EGFR) of tumor cells could be prepared with dye to protein ratios between 0.3 and 2.2 to assess their potential as imaging probes. For the first time, ctx conjugates could be achieved without showing a decrease in Φf and with an increasing labeling degree that exceeded the value of the pure dye even at a labeling degree above 2. The incorporation of hydrophilically and sterically demanding dendrimers into cyanines prevented dimer formation after covalent conjugation to the antibody. The binding functionality of the resulting ctx conjugates to the EGFR was successfully demonstrated by cell microscopy studies using EGFR expressing cell lines. In summary, the combination of hydrophilic glycerol dendrons with reactive dye labels has been established for the first time and is a promising Approach toward more powerful fluorescent labels with less dimerization. KW - Dye KW - Quantum yield KW - Fluorescence KW - Contrast agent KW - Extinction coefficient PY - 2015 DO - https://doi.org/10.1021/acs.bioconjchem.5b00097 SN - 1043-1802 VL - 26 SP - 773 EP - 781 PB - ACS Publications CY - Washington AN - OPUS4-38880 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Gawlitza, Kornelia A1 - Wan, Wei A1 - Wagner, Sabine A1 - Rurack, Knut ED - Tiwari, Ashutosh ED - Uzun, Lokman T1 - Fluorescent Molecularly Imprinted Polymers N2 - An ideal sensor system is a combination of a selective receptor, an effective transducer, and a sensitive detector. To utilize molecularly imprinted polymers (MIPs) as responsive recognition phases in sensors, the employment of fluorescent molecules or nanoparticles (NPs) that show prominent changes in their spectroscopic properties after binding of the target molecule in the MIP’s cavity is particularly attractive. Such fluorescent MIPs (fMIPs) act through target-induced quenching, enhancement, or spectral shifts of the fluorescence. This contribution introduces different strategies of incorporation of fluorescent dyes, probes, and NPs into fMIPs. In addition, various sensing mechanisms are reviewed, and depending on the application of the sensor, the different deployable formats, their advantages, drawbacks, and impact will be presented and discussed. KW - Dyes KW - Fluorescence KW - Molecular imprinted polymers KW - Quantum dots KW - Sensors PY - 2017 SN - 978-1-119-33629-7 SP - 89 EP - 128 PB - Scrivener Publishing, WILEY CY - Beverly, MA ET - 1 AN - OPUS4-38798 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rurack, Knut T1 - The Integration of Fluorescent Probes with Sensing Matrices N2 - Integrating fluorescent probes with sensing matrices presents a major challenge because usually, when confined in a rather rigid matrix, fluorophores tend to behave completely different than for instance in the molecular state in solution. The lecture reviews the major strategies that have been devised recently to circumvent such issues with special focus on the works carried out in this field by BAM’s Chemical and Optical Sensing Division. Moreover, it will be shown that by using certain strategies not only can the response behavior be retained but synergistic effects can even endow the hybrid with a much better performance than the probe molecule alone. T2 - GDCh-Kolloquium CY - Braunschweig, Germany DA - 14.11.2016 KW - Fluorescence KW - Probes KW - Sensor KW - Molecularly imprinted polymers KW - Gated release systems PY - 2016 AN - OPUS4-38794 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -