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 - 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 - 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 - 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 - 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 - 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 - TY - GEN A1 - Lemke, Matthias A1 - Fernández-Trujillo, Rebeca A1 - Löhmannsröben, Hans-Gerd T1 - In-situ LIF analysis of biological and petroleum-based hydraulic oils on soil N2 - Absorption and fluorescence properties of 4 hydraulic oils (3 biological and 1 petroleum-based) were investigated. In-situ LIF (laser-induced fluorescence) analysis of the oils on a brown sandy loam soil was performed. With calibration, quantitative detection was achieved. Estimated limits of detection were below ca. 500 mg/kg for the petroleum-based oil and ca. 2000 mg/kg for one biological oil. A semi-quantitative classification scheme is proposed for monitoring of the biological oils. This approach was applied to investigate the migration of a biological oil in soil-containing compartments, namely a soil column and a soil bed. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 011 KW - in-situ KW - optical oil sensor KW - lubricants KW - hydraulic oils KW - soil KW - laser induced Y1 - 2005 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-12268 ER - TY - GEN A1 - Löhmannsröben, Hans-Gerd A1 - Kantor, Zoltan A1 - Kumke, Michael Uwe A1 - Schmälzlin, Elmar A1 - Reich, Oliver T1 - OPQS – optische Prozess- und Qualitäts-Sensorik N2 - Im vorliegenden Beitrag wird an Hand dreier Beispiele der Einsatz von optischer Sensorik zur Produktcharakterisierung dargestellt, nämlich Untersuchungen zum O2-Gehalt in Fruchtsäften, zur Isotopiesignatur von CO2 in Mineralwässern und zu Lichtstreueigenschaften eines Sonnenschutzmittels. Inhalt: Bestimmung von O2 mit Lumineszenzsonden Isotopenselektive Bestimmung von CO2 mit TDLAS Optische Charakterisierung stark streuender Materialien mit Photonendichtewellen T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 028 KW - Sensorik KW - Prozesskontrolle KW - Absorption KW - Lumineszenz KW - Lichtstreuung KW - Isotopie Y1 - 2005 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-13205 ER - TY - GEN A1 - Schmälzlin, Elmar A1 - Dongen, Joost T. van A1 - Klimant, Ingo A1 - Marmodée, Bettina A1 - Steup, Martin A1 - Fishahn, Joachim A1 - Geigenberger, Peter A1 - Löhmannsröben, Hans-Gerd T1 - An optical multifrequency phase-modulation method using microbeads for measuring intracellular oxygen concentrations in plants N2 - A technique has been developed to measure absolute intracellular oxygen concentrations in green plants. Oxygen-sensitive phosphorescent microbeads were injected into the cells and an optical multifrequency phase-modulation technique was used to discriminate the sensor signal from the strong autofluorescence of the plant tissue. The method was established using photosynthesis-competent cells of the giant algae Chara corallina L., and was validated by application to various cell types of other plant species. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 007 Y1 - 2005 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-12232 ER -