TY - JOUR A1 - Lokstein, Heiko A1 - Krikunova, Maria A1 - Teuchner, Klaus A1 - Voigt, Bernd T1 - Elucidation of structure-function relationships in photosynthetic light-harvesting antenna complexes by non-linear polarization spectroscopy in the frequency domain (NLPF) JF - Journal of plant physiology : biochemistry, physiology, molecular biology and biotechnology of plants N2 - Photosynthetically active pigments are usually organized into pigment-protein complexes. These include light-harvesting antenna complexes (LHCs) and reaction centers. Site energies of the bound pigments are determined by interactions with their environment, i.e., by pigment-protein as well as pigment-pigment interactions. Thus, resolution of spectral substructures of the pigment-protein complexes may provide valuable insight into structure-function relationships. By means of conventional (linear) and time-resolved spectroscopic techniques, however, it is often difficult to resolve the spectral substructures of complex pigment-protein assemblies. Nonlinear polarization spectroscopy in the frequency domain (NLPF) is shown to be a valuable technique in this regard. Based on initial experimental work with purple bacterial antenna complexes as well as model systems NLPF has been extended to analyse the substructure(s) of very complex spectra, including analyses of interactions between chlorophylls and "optically dark" states of carotenoids in LHCs. The paper reviews previous work and outlines perspectives regarding the application of NLPF spectroscopy to disentangle structure-function relationships in pigment-protein complexes. KW - Excitonic interactions KW - Laser spectroscopy KW - Light-harvesting complex KW - Nonlinear polarization spectroscopy in the frequency domain KW - Pigment-pigment interactions Y1 - 2011 U6 - https://doi.org/10.1016/j.jplph.2010.12.012 SN - 0176-1617 VL - 168 IS - 12 SP - 1488 EP - 1496 PB - Elsevier CY - Jena ER - TY - JOUR A1 - Reiche, Jürgen A1 - Kratz, Karl A1 - Hofmann, Dieter A1 - Lendlein, Andreas T1 - Current status of Langmuir monolayer degradation of polymeric biomaterials JF - The international journal of artificial organs N2 - Langmuir monolayer degradation (LMD) experiments with polymers possessing outstanding biomedical application potential yield information regarding the kinetics of their hydrolytic or enzymatic chain scission under well-defined and adjustable degradation conditions. A brief review is given of LMD investigations, including the author's own work on 2-dimensional (2D) polymer systems, providing chain scission data, which are not disturbed by simultaneously occurring transport phenomena, such as water penetration into the sample or transport of scission fragments out of the sample. A knowledge-based approach for the description and simulation of polymer hydrolytic and enzymatic degradation based on a combination of fast LMD experiments and computer simulation of the water penetration is briefly introduced. Finally, the advantages and disadvantages of this approach are discussed. KW - Monolayer KW - Hydrolytic degradation KW - Enzymatic degradation KW - Biomaterial KW - Degradable polymer Y1 - 2011 U6 - https://doi.org/10.5301/IJAO.2011.6401 SN - 0391-3988 VL - 34 IS - 2 SP - 123 EP - 128 PB - Wichtig CY - Milano ER - TY - JOUR A1 - Beta, Carsten A1 - Bodenschatz, Eberhard T1 - Microfluidic tools for quantitative studies of eukaryotic chemotaxis JF - European journal of cell biology N2 - Over the past decade, microfluidic techniques have been established as a versatile platform to perform live cell experiments under well-controlled conditions. To investigate the directional responses of cells, stable concentration profiles of chemotactic factors can be generated in microfluidic gradient mixers that provide a high degree of spatial control. However, the times for built-up and switching of gradient profiles are in general too slow to resolve the intracellular protein translocation events of directional sensing of eukaryotes. Here, we review an example of a conventional microfluidic gradient mixer as well as the novel flow photolysis technique that achieves an increased temporal resolution by combining the photo-activation of caged compounds with the advantages of microfluidic chambers. KW - Eukaryotic chemotaxis KW - Dictyostelium discoideum KW - Microfluidics KW - Caged compounds KW - Numerical simulations Y1 - 2011 U6 - https://doi.org/10.1016/j.ejcb.2011.05.006 SN - 0171-9335 VL - 90 IS - 10 SP - 811 EP - 816 PB - Elsevier CY - Jena ER -