TY - GEN A1 - Schmälzlin, Elmar A1 - Walz, Bernd A1 - Klimant, Ingo A1 - Schewe, Bettina A1 - Löhmannsröben, Hans-Gerd T1 - Monitoring hormone-induced oxygen consumption in the salivary glands of the blowfly, Calliphora vicina, by use of luminescent microbeads N2 - The salivary glands of the blowfly were injected with luminescent oxygen-sensitive microbeads. The changes in oxygen content within individual gland tubules during hormone-induced secretory activity were quantified. The measurements are based on an upgraded phase-modulation technique, where the phase shift of the sensor phosphorescence is determined independently from concentration and background signals. We show that the combination of a lock-in amplifier with a fluorescence microscope results in a convenient setup to measure oxygen concentrations within living animal tissues at the cellular level. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 006 Y1 - 2006 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-12206 ER - TY - GEN A1 - Niederkrüger, Matthias A1 - Salb, Christian A1 - Beck, Michael A1 - Hildebrandt, Niko A1 - Löhmannsröben, Hans-Gerd A1 - Marowsky, Gerd T1 - Improvement of a fluorescence immunoassay with a compact diode-pumped solid state laser at 315 nm N2 - We demonstrate the improvement of fluorescence immunoassay (FIA) diagnostics in deploying a newly developed compact diode-pumped solid state (DPSS) laser with emission at 315 nm. The laser is based on the quasi-three-level transition in Nd:YAG at 946 nm. The pulsed operation is either realized by an active Q-switch using an electro-optical device or by introduction of a Cr4+:YAG saturable absorber as passive Q-switch element. By extra-cavity second harmonic generation in different nonlinear crystal media we obtained blue light at 473 nm. Subsequent mixing of the fundamental and the second harmonic in a β-barium-borate crystal provided pulsed emission at 315 nm with up to 20 μJ maximum pulse energy and 17 ns pulse duration. Substitution of a nitrogen laser in a FIA diagnostics system by the DPSS laser succeeded in considerable improvement of the detection limit. Despite significantly lower pulse energies (7 μJ DPSS laser versus 150 μJ nitrogen laser), in preliminary investigations the limit of detection was reduced by a factor of three for a typical FIA. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 016 KW - Immunoassay KW - Fluoreszenz-Resonanz-Energie-Transfer KW - Neodym-YAG-Laser KW - 946 nm KW - 473 nm KW - 315 nm KW - gepulster DPSS Laser KW - sättigbarer Absorber KW - fluorescence immunoassay KW - 946 nm KW - 473 nm KW - 315 nm KW - pulsed DPSS laser Y1 - 2006 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-10150 ER - TY - GEN A1 - Löhmannsröben, Hans-Gerd A1 - Beck, Michael A1 - Hildebrandt, Niko A1 - Schmälzlin, Elmar A1 - van Dongen, Joost T. T1 - New challenges in biophotonics : laser-based fluoroimmuno analysis and in-vivo optical oxygen monitoring N2 - Two examples of our biophotonic research utilizing nanoparticles are presented, namely laser-based fluoroimmuno analysis and in-vivo optical oxygen monitoring. Results of the work include significantly enhanced sensitivity of a homogeneous fluorescence immunoassay and markedly improved spatial resolution of oxygen gradients in root nodules of a legume species. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 018 KW - Sauerstoff KW - Quantenpunkt KW - Lumineszenz KW - Immunoassay KW - Energietransfer KW - Fluoreszenz-Resonanz-Energie-Transfer KW - Nanopartikel KW - Lanthanoide KW - Optode KW - Förster Resonanz Energie Transfer KW - Biophotonik KW - biophotonics KW - nanoparticles KW - immunoassay KW - oxygen KW - optode Y1 - 2006 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-10120 ER - TY - GEN A1 - Lau, Steffen A1 - Salffner, Katharina A1 - Löhmannsröben, Hans-Gerd T1 - Isotopic resolution of carbon monoxide and carbon dioxide by NIR diode laser spectroscopy N2 - Near-infrared (NIR) absorption spectroscopy with tunable diode lasers allows the simultaneous detection of the three most important isotopologues of carbon dioxide (12CO2, 13CO2, 12C18O16O) and carbon monoxide (12CO, 13CO, 12C18O). The flexible and compact fiber-optic tunable diode laser absorption spectrometer (TDLAS) allows selective measurements of CO2 and CO with high isotopic resolution without sample preparation since there is no interference with water vapour. For each species, linear calibration plots with a dynamic range of four orders of magnitude and detection limits (LOD) in the range of a few ppm were obtained utilizing wavelength modulation spectroscopy (WMS) with balanced detection in a Herriott-type multipass cell. The high performance of the apparatus is illustrated by fill-evacuation-refill cycles. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 017 KW - Isotop KW - Kohlenmonoxid KW - Kohlendioxid KW - Diodenlaserspektroskopie KW - isotope KW - carbon monoxide KW - carbon dioxide KW - diode laser spectroscopy Y1 - 2006 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-10135 ER - TY - JOUR A1 - Kumke, Michael Uwe A1 - Dosche, Carsten A1 - Flehr, Roman A1 - Trowitzsch-Kienast, Wolfram A1 - Löhmannsröben, Hans-Gerd T1 - Spectroscopic characterization of the artificial siderophore pyridinochelin Y1 - 2006 UR - http://www.znaturforsch.com/c.htm SN - 0939-5075 ER - TY - GEN A1 - Hildebrandt, Nico A1 - Charbonnière, Loïc J. A1 - Ziessel, Raymond F. A1 - Löhmannsröben, Hans-Gerd T1 - Quantum dots as resonance energy transfer acceptors for monitoring biological interactions N2 - Quantum dots (QDs) are common as luminescing markers for imaging in biological applications because their optical properties seem to be inert against their surrounding solvent. This, together with broad and strong absorption bands and intense, sharp tuneable luminescence bands, makes them interesting candidates for methods utilizing Forster Resonance Energy Transfer (FRET), e. g. for sensitive homogeneous fluoroimmunoassays (FIA). In this work we demonstrate energy transfer from Eu3+-trisbipyridin (Eu-TBP) donors to CdSe-ZnS-QD acceptors in solutions with and without serum. The QDs are commercially available CdSe-ZnS core-shell particles emitting at 655 nm (QD655). The FRET system was achieved by the binding of the streptavidin conjugated donors with the biotin conjugated acceptors. After excitation of Eu-TBP and as result of the energy transfer, the luminescence of the QD655 acceptors also showed lengthened decay times like the donors. The energy transfer efficiency, as calculated from the decay times of the bound and the unbound components, amounted to 37%. The Forster-radius, estimated from the absorption and emission bands, was ca. 77Å. The effective binding ratio, which not only depends on the ratio of binding pairs but also on unspecific binding, was obtained from the donor emission dependent on the concentration. As serum promotes unspecific binding, the overall FRET efficiency of the assay was reduced. We conclude that QDs are good substitutes for acceptors in FRET if combined with slow decay donors like Europium. The investigation of the influence of the serum provides guidance towards improving binding properties of QD assays. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 012 Y1 - 2006 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-12213 ER - TY - GEN A1 - Engelhard, Sonja A1 - Kumke, Michael Uwe A1 - Löhmannsröben, Hans-Gerd T1 - OPQS – optical process and quality sensing : exemplary applications in the beerbrewing and polyurethane foaming processes N2 - Optical methods play an important role in process analytical technologies (PAT). Four examples of optical process and quality sensing (OPQS) are presented, which are based on three important experimental techniques: near-infrared absorption, luminescence quenching, and a novel method, photon density wave (PDW) spectroscopy. These are used to evaluate four process and quality parameters related to beer brewing and polyurethane (PU) foaming processes: the ethanol content and the oxygen (O2) content in beer, the biomass in a bioreactor, and the cellular structures of PU foam produced in a pilot production plant. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 004 KW - process analytical technology KW - beer KW - biomass KW - foam analysis KW - NIR spectroscopy KW - fluorescence quenching KW - photon density wave spectroscopy Y1 - 2006 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-12191 ER - TY - JOUR A1 - Engelhard, Sonja A1 - Kumke, Michael Uwe A1 - Löhmannsröben, Hans-Gerd T1 - Examples of the application of optical process and quality sensing (OPQS) to beer brewing and polyurethane foaming processes N2 - Optical methods play an important role in process analytical technologies (PAT). Four examples of optical process and quality sensing (OPQS) are presented, which are based on three important experimental techniques: near- infrared absorption, luminescence quenching, and a novel method, photon density wave (PDW) spectroscopy. These are used to evaluate four process and quality parameters related to beer brewing and polyurethane (PU) foaming processes: the ethanol content and the oxygen (O-2) content in beer, the biomass in a bioreactor, and the cellular structures of PU foam produced in a pilot production plant Y1 - 2006 UR - http://www.springerlink.com/content/100417 U6 - https://doi.org/10.1007/s00216-005-3364-4 SN - 1618-2642 ER - TY - JOUR A1 - Beitz, Toralf A1 - Laudien, Robert A1 - Löhmannsröben, Hans-Gerd A1 - Kallies, Bernd T1 - Ion mobility spectrometric investigation of aromatic cations in the gas phase N2 - In this work, ion mobility (IM) spectra of more than 50 aromatic compounds were recorded with a laser-based IM spectrometer at atmospheric pressure. IM spectra of PAH in the laser desorption experiment show a high complexity resulting from the occurrence of monomeric, dimeric, and oligomeric cluster ions. The mobilities of all compounds were determined in helium as drift gas. This allows the calculation of the diffusion cross sections (Omega(calc)) on the basis of the exact hard sphere scattering model and their comparison with the experimentally determined diffusion cross sections (Omega(exp)). Extended Omega(exp)/Omega(calc) and Omega(exp/)mass correlations were performed in order to gain insight into conformational properties of cationic alkyl benzenes and internal rotation of phenyl rings in aromatic ions. This is demonstrated with some examples, such as the evaluation of the dihedral angle of the ions of 9,10- diphenylanthracene, o- and m-terphenyl, and 1,2,3- and 1,3,5-triphenylbenzene. Furthermore, sandwich and T-structures of dimeric PAH cations are discussed. The analysis was extended to oligomeric ions with up to nine monomer units. Experimental evidence is presented suggesting the formation of pi-stacks with a transition toward modified pi-stacks with increasing cluster size. The distance between monomeric units in dimeric and oligomeric ions was obtained Y1 - 2006 UR - http://pubs.acs.org/journal/jpcafh U6 - https://doi.org/10.1021/Jp055335n SN - 1089-5639 ER - TY - GEN A1 - Beck, Michael A1 - Hildebrandt, Niko A1 - Löhmannsröben, Hans-Gerd T1 - Quantum dots as acceptors in FRET-assays containing serum N2 - Quantum dots (QDs) are common as luminescing markers for imaging in biological applications because their optical properties seem to be inert against their surrounding solvent. This, together with broad and strong absorption bands and intense, sharp tuneable luminescence bands, makes them interesting candidates for methods utilizing Förster Resonance Energy Transfer (FRET), e. g. for sensitive homogeneous fluoroimmunoassays (FIA). In this work we demonstrate energy transfer from Eu3+-trisbipyridin (Eu-TBP) donors to CdSe-ZnS-QD acceptors in solutions with and without serum. The QDs are commercially available CdSe-ZnS core-shell particles emitting at 655 nm (QD655). The FRET system was achieved by the binding of the streptavidin conjugated donors with the biotin conjugated acceptors. After excitation of Eu-TBP and as result of the energy transfer, the luminescence of the QD655 acceptors also showed lengthened decay times like the donors. The energy transfer efficiency, as calculated from the decay times of the bound and the unbound components, amounted to 37%. The Förster-radius, estimated from the absorption and emission bands, was ca. 77 Å. The effective binding ratio, which not only depends on the ratio of binding pairs but also on unspecific binding, was obtained from the donor emission dependent on the concentration. As serum promotes unspecific binding, the overall FRET efficiency of the assay was reduced. We conclude that QDs are good substitutes for acceptors in FRET if combined with slow decay donors like Europium. The investigation of the influence of the serum provides guidance towards improving binding properties of QD assays. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 019 KW - Quantenpunkt KW - Lumineszenz KW - Serum KW - Europium KW - Immunoassay KW - Energietransfer KW - Fluoreszenz-Resonanz-Energie-Transfer KW - Förster-Resonanz-Energie-Transfer KW - Quantum Dot KW - Luminescence KW - Serum KW - Europium KW - Immunoassay KW - Energy Transfer KW - FRET Y1 - 2006 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-9504 ER -