TY - JOUR A1 - Eisold, Ursula A1 - Kupstat, Annette A1 - Klier, Dennis Tobias A1 - Primus, Philipp-A. A1 - Pschenitza, Michael A1 - Niessner, Reinhard A1 - Knopp, Dietmar A1 - Kumke, Michael Uwe T1 - Probing the physicochemical interactions of 3-hydroxy-benzo[a]pyrene with different monoclonal and recombinant antibodies by use of fluorescence line-narrowing spectroscopy JF - Analytical & bioanalytical chemistry N2 - Characterization of interactions between antigens and antibodies is of utmost importance both for fundamental understanding of the binding and for development of advanced clinical diagnostics. Here, fluorescence line-narrowing (FLN) spectroscopy was used to study physicochemical interactions between 3-hydroxybenzo[a]pyrene (3OH-BaP, as antigen) and a variety of solvent matrices (as model systems) or anti-polycyclic aromatic hydrocarbon antibodies (anti-PAH). We focused the studies on the specific physicochemical interactions between 3OH-BaP and different, previously obtained, monoclonal and recombinant anti-PAH antibodies. Control experiments performed with non-binding monoclonal antibodies and bovine serum albumin (BSA) indicated that nonspecific interactions did not affect the FLN spectrum of 3OH-BaP. The spectral positions and relative intensities of the bands in the FLN spectra are highly dependent on the molecular environment of the 3OH-BaP. The FLN bands correlate with different vibrational modes of 3OH-BaP which are affected by interactions with the molecular environment (pi-pi interactions, H-bonding, or van-der-Waals forces). Although the analyte (3OH-BaP) was the same for all the antibodies investigated, different binding interactions could be identified from the FLN spectra on the basis of structural flexibility and conformational multiplicity of the antibodies' paratopes. KW - FLNS KW - Antibody KW - Paratope KW - Hapten KW - Polycyclic aromatic hydrocarbons Y1 - 2014 U6 - https://doi.org/10.1007/s00216-013-7584-8 SN - 1618-2642 SN - 1618-2650 VL - 406 IS - 14 SP - 3387 EP - 3394 PB - Springer CY - Heidelberg ER - TY - JOUR A1 - Hesse, Julia A1 - Klier, Dennis Tobias A1 - Sgarzi, Massimo A1 - Nsubuga, Anne A1 - Bauer, Christoph A1 - Grenzer, Joerg A1 - Hübner, Rene A1 - Wislicenus, Marcus A1 - Joshi, Tanmaya A1 - Kumke, Michael Uwe A1 - Stephan, Holger T1 - Rapid Synthesis of Sub-10nm Hexagonal NaYF4-Based Upconverting Nanoparticles using Therminol((R))66 JF - ChemistryOpen : including thesis treasury N2 - We report a simple one-pot method for the rapid preparation of sub-10nm pure hexagonal (-phase) NaYF4-based upconverting nanoparticles (UCNPs). Using Therminol((R))66 as a co-solvent, monodisperse UCNPs could be obtained in unusually short reaction times. By varying the reaction time and reaction temperature, it was possible to control precisely the particle size and crystalline phase of the UCNPs. The upconversion (UC) luminescence properties of the nanocrystals were tuned by varying the concentrations of the dopants (Nd3+ and Yb3+ sensitizer ions and Er3+ activator ions). The size and phase-purity of the as-synthesized core and core-shell nanocrystals were assessed by using complementary transmission electron microscopy, dynamic light scattering, X-ray diffraction, and small-angle X-ray scattering studies. In-depth photophysical evaluation of the UCNPs was pursued by using steady-state and time-resolved luminescence spectroscopy. An enhancement in the UC intensity was observed if the nanocrystals, doped with optimized concentrations of lanthanide sensitizer/activator ions, were further coated with an inert/active shell. This was attributed to the suppression of surface-related luminescence quenching effects. KW - core-shell materials KW - lanthanides KW - nanostructures KW - photoluminescence KW - upconversion Y1 - 2018 U6 - https://doi.org/10.1002/open.201700186 SN - 2191-1363 VL - 7 IS - 2 SP - 159 EP - 168 PB - Wiley-VCH CY - Weinheim ER - TY - GEN A1 - Hesse, Julia A1 - Klier, Dennis Tobias A1 - Sgarzi, Massimo A1 - Nsubuga, Anne A1 - Bauer, Christoph A1 - Grenzer, Jörg A1 - Hübner, René A1 - Wislicenus, Marcus A1 - Joshi, Tanmaya A1 - Kumke, Michael Uwe A1 - Stephan, Holger T1 - Rapid synthesis of sub-10 nm hexagonal NaYF4-based upconverting nanoparticles using Therminol® 66 T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - We report a simple one-pot method for the rapid preparation of sub-10nm pure hexagonal (-phase) NaYF4-based upconverting nanoparticles (UCNPs). Using Therminol((R))66 as a co-solvent, monodisperse UCNPs could be obtained in unusually short reaction times. By varying the reaction time and reaction temperature, it was possible to control precisely the particle size and crystalline phase of the UCNPs. The upconversion (UC) luminescence properties of the nanocrystals were tuned by varying the concentrations of the dopants (Nd3+ and Yb3+ sensitizer ions and Er3+ activator ions). The size and phase-purity of the as-synthesized core and core-shell nanocrystals were assessed by using complementary transmission electron microscopy, dynamic light scattering, X-ray diffraction, and small-angle X-ray scattering studies. In-depth photophysical evaluation of the UCNPs was pursued by using steady-state and time-resolved luminescence spectroscopy. An enhancement in the UC intensity was observed if the nanocrystals, doped with optimized concentrations of lanthanide sensitizer/activator ions, were further coated with an inert/active shell. This was attributed to the suppression of surface-related luminescence quenching effects. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 613 KW - core-shell materials KW - lanthanides KW - nanostructures KW - photoluminescence KW - upconversion Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-423515 SN - 1866-8372 IS - 613 ER - TY - JOUR A1 - Klier, Dennis Tobias A1 - Kumke, Michael Uwe T1 - Upconversion NaYF4:Yb:Er nanoparticles co-doped with Gd3+ and Nd3+ for thermometry on the nanoscale JF - RSC Advances : an international journal to further the chemical sciences N2 - In the present work, the upconversion luminescence properties of oleic acid capped NaYF4:Gd3+:Yb3+:Er3+ upconversion nanoparticles (UCNP) with pure β crystal phase and Nd3+ ions as an additional sensitizer were studied in the temperature range of 288 K < T < 328 K. The results of this study showed that the complex interplay of different mechanisms and effects, causing the special temperature behavior of the UCNP can be developed into thermometry on the nanoscale, e.g. to be applied in biological systems on a cellular level. The performance was improved by the use of Nd3+ as an additional dopant utilizing the cascade sensitization mechanism in tri-doped UCNP. Y1 - 2015 U6 - https://doi.org/10.1039/C5RA11502G SN - 2046-2069 IS - 5 SP - 67149 EP - 67156 PB - RSC Publishing CY - London ER - TY - GEN A1 - Klier, Dennis Tobias A1 - Kumke, Michael Uwe T1 - Upconversion NaYF4:Yb:Er nanoparticles co-doped with Gd3+ and Nd3+ for thermometry on the nanoscale N2 - In the present work, the upconversion luminescence properties of oleic acid capped NaYF4:Gd3+:Yb3+:Er3+ upconversion nanoparticles (UCNP) with pure β crystal phase and Nd3+ ions as an additional sensitizer were studied in the temperature range of 288 K < T < 328 K. The results of this study showed that the complex interplay of different mechanisms and effects, causing the special temperature behavior of the UCNP can be developed into thermometry on the nanoscale, e.g. to be applied in biological systems on a cellular level. The performance was improved by the use of Nd3+ as an additional dopant utilizing the cascade sensitization mechanism in tri-doped UCNP. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 216 Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-89618 SP - 67149 EP - 67156 ER - TY - JOUR A1 - Klier, Dennis Tobias A1 - Kumke, Michael Uwe T1 - Analysing the effect of the crystal structure on upconversion luminescence in Yb3+,Er3+-co-doped NaYF4 nanomaterials JF - Journal of materials chemistry C ; Materials for optical and electronic devices N2 - NaYF4:Yb:Er nanoparticles (UCNP) were synthesized under mild experimental conditions to obtain a pure cubic lattice. Upon annealing at different temperatures up to Tan = 700 °C phase transitions to the hexagonal phase and back to the cubic phase were induced. The UCNP materials obtained for different Tan were characterized with respect to the lattice phase using standard XRD and Raman spectroscopy as well as steady state and time resolved upconversion luminescence. The standard techniques showed that for the annealing temperature range 300 °C < Tan < 600 °C the hexagonal lattice phase was dominant. For Tan < 300 °C hardly any change in the lattice phase could be deduced, whereas for Tan > 600 °C a back transfer to the α-phase was observed. Complementarily, the luminescence upconversion properties of the annealed UCNP materials were characterized in steady state and time resolved luminescence measurements. Distinct differences in the upconversion luminescence intensity, the spectral intensity distribution and the luminescence decay kinetics were found for the cubic and hexagonal lattice phases, respectively, corroborating the results of the standard analytical techniques used. In laser power dependent measurements of the upconversion luminescence intensity it was found that the green (G1, G2) and red (R) emission of Er3+ showed different effects of Tan on the number of required photons reflecting the differences in the population routes of different energy levels involved. Furthermore, the intensity ratio of Gfull/R is highly effected by the laser power only when the β-phase is present, whereas the G1/G2 intensity ratio is only slightly effected regardless of the crystal phase. Moreover, based on different upconversion luminescence kinetics characteristics of the cubic and hexagonal phase time-resolved area normalized emission spectra (TRANES) proved to be a very sensitive tool to monitor the phase transition between cubic and hexagonal phases. Based on the TRANES analysis it was possible to resolve the lattice phase transition in more detail for 200 °C < Tan < 300 °C, which was not possible with the standard techniques. Y1 - 2015 U6 - https://doi.org/10.1039/C5TC02218E SN - 2050-7526 SN - 2050-7534 IS - 3 SP - 11228 EP - 11238 PB - Royal Society of Chemistry CY - Cambridge ER - TY - GEN A1 - Klier, Dennis Tobias A1 - Kumke, Michael Uwe T1 - Analysing the effect of the crystal structure on upconversion luminescence in Yb3+,Er3+-co-doped NaYF4 nanomaterials N2 - NaYF4:Yb:Er nanoparticles (UCNP) were synthesized under mild experimental conditions to obtain a pure cubic lattice. Upon annealing at different temperatures up to Tan = 700 °C phase transitions to the hexagonal phase and back to the cubic phase were induced. The UCNP materials obtained for different Tan were characterized with respect to the lattice phase using standard XRD and Raman spectroscopy as well as steady state and time resolved upconversion luminescence. The standard techniques showed that for the annealing temperature range 300 °C < Tan < 600 °C the hexagonal lattice phase was dominant. For Tan < 300 °C hardly any change in the lattice phase could be deduced, whereas for Tan > 600 °C a back transfer to the α-phase was observed. Complementarily, the luminescence upconversion properties of the annealed UCNP materials were characterized in steady state and time resolved luminescence measurements. Distinct differences in the upconversion luminescence intensity, the spectral intensity distribution and the luminescence decay kinetics were found for the cubic and hexagonal lattice phases, respectively, corroborating the results of the standard analytical techniques used. In laser power dependent measurements of the upconversion luminescence intensity it was found that the green (G1, G2) and red (R) emission of Er3+ showed different effects of Tan on the number of required photons reflecting the differences in the population routes of different energy levels involved. Furthermore, the intensity ratio of Gfull/R is highly effected by the laser power only when the β-phase is present, whereas the G1/G2 intensity ratio is only slightly effected regardless of the crystal phase. Moreover, based on different upconversion luminescence kinetics characteristics of the cubic and hexagonal phase time-resolved area normalized emission spectra (TRANES) proved to be a very sensitive tool to monitor the phase transition between cubic and hexagonal phases. Based on the TRANES analysis it was possible to resolve the lattice phase transition in more detail for 200 °C < Tan < 300 °C, which was not possible with the standard techniques. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 217 Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-89630 SP - 11228 EP - 11238 ER - TY - JOUR A1 - Klier, Dennis Tobias A1 - Kumke, Michael Uwe T1 - Analysing the effect of the crystal structure on upconversion luminescence in Yb3+, Er3+-co-doped NaYF4 nanomaterials JF - Journal of materials chemistry : C, Materials for optical and electronic devices N2 - NaYF4:Yb:Er nanoparticles (UCNP) were synthesized under mild experimental conditions to obtain a pure cubic lattice. Upon annealing at different temperatures up to T-an = 700 degrees C phase transitions to the hexagonal phase and back to the cubic phase were induced. The UCNP materials obtained for different T-an were characterized with respect to the lattice phase using standard XRD and Raman spectroscopy as well as steady state and time resolved upconversion luminescence. The standard techniques showed that for the annealing temperature range 300 degrees C < T-an < 600 degrees C the hexagonal lattice phase was dominant. For T-an < 300 degrees C hardly any change in the lattice phase could be deduced, whereas for T-an > 600 degrees C a back transfer to the alpha-phase was observed. Complementarily, the luminescence upconversion properties of the annealed UCNP materials were characterized in steady state and time resolved luminescence measurements. Distinct differences in the upconversion luminescence intensity, the spectral intensity distribution and the luminescence decay kinetics were found for the cubic and hexagonal lattice phases, respectively, corroborating the results of the standard analytical techniques used. In laser power dependent measurements of the upconversion luminescence intensity it was found that the green (G1, G2) and red (R) emission of Er3+ showed different effects of T-an on the number of required photons reflecting the differences in the population routes of different energy levels involved. Furthermore, the intensity ratio of G(full)/R is highly effected by the laser power only when the beta-phase is present, whereas the G1/G2 intensity ratio is only slightly effected regardless of the crystal phase. Moreover, based on different upconversion luminescence kinetics characteristics of the cubic and hexagonal phase time-resolved area normalized emission spectra (TRANES) proved to be a very sensitive tool to monitor the phase transition between cubic and hexagonal phases. Based on the TRANES analysis it was possible to resolve the lattice phase transition in more detail for 200 degrees C < T-an < 300 degrees C, which was not possible with the standard techniques. Y1 - 2015 U6 - https://doi.org/10.1039/c5tc02218e SN - 2050-7526 SN - 2050-7534 VL - 3 IS - 42 SP - 11228 EP - 11238 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Klier, Dennis Tobias A1 - Kumke, Michael Uwe T1 - Upconversion Luminescence Properties of NaYF4:Yb:Er Nanoparticles Codoped with Gd3+ JF - The journal of physical chemistry : C, Nanomaterials and interfaces N2 - The temperature-dependent upconversion luminescence of NaYF4:Yb:Er nanoparticles (UCNP) containing different contents of Gd3+ as additional dopant was characterized. The UCNP were synthesized in a hydrothermal synthesis and stabilized with citrate in order to transfer them to the water phase. Basic characterization was carried out using TEM and DLS to determine the average size of the UCNP. The XRD technique was used to investigate the crystal lattice of the UCNP. It was found that due to the presence of Gd3+, an alteration of the lattice phase from a to beta was induced which was also reflected in the observed upconversion luminescence properties of the UCNP. A detailed analysis of the upconversion luminescence spectraespecially at ultralow temperaturesrevealed the different effects of phonon coupling between the host lattice and the sensitizer (Yb3+) as well as the activator (Er3+). Furthermore, the upconversion luminescence intensity reached a maximum between 15 and 250 K depending on Gd3+ content. In comparison to the very complex temperature behavior of the upconversion luminescence in the temperature range <273 K, the luminescence intensity ratio of H-2(11/2)-> I-4(15/2) to S-4(3/2)-> I-4(15/2) (R = G1/G2) in a higher temperature range can be described by an Arrhenius-type equation. Y1 - 2015 U6 - https://doi.org/10.1021/jp5103548 SN - 1932-7447 VL - 119 IS - 6 SP - 3363 EP - 3373 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Klier, Dennis Tobias A1 - Kumke, Michael Uwe T1 - Upconversion NaYF4:Yb:Er nanoparticles co-doped with Gd3+ and Nd3+ for thermometry on the nanoscale JF - RSC Advances N2 - In the present work, the upconversion luminescence properties of oleic acid capped NaYF4:Gd3+:Yb3+:Er3+ upconversion nanoparticles (UCNP) with pure beta crystal phase and Nd3+ ions as an additional sensitizer were studied in the temperature range of 288 K < T < 328 K. The results of this study showed that the complex interplay of different mechanisms and effects, causing the special temperature behavior of the UCNP can be developed into thermometry on the nanoscale, e.g. to be applied in biological systems on a cellular level. The performance was improved by the use of Nd3+ as an additional dopant utilizing the cascade sensitization mechanism in tri-doped UCNP. Y1 - 2015 U6 - https://doi.org/10.1039/c5ra11502g SN - 2046-2069 VL - 5 IS - 82 SP - 67149 EP - 67156 PB - Royal Society of Chemistry CY - Cambridge ER -