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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 -