Wechselwirkungen von polyphilen Molekülen mit Lipidmonolayern und Lipidvesikeln

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Goals of this project are investigations and elucidation of the interactions of low molecular weight and polymeric polyphilic molecules in aqueous solution with lipid model membranes and lipid monolayers. Low molecular weight polyphiles will have T- and X-like structures and will be synthesized in the group of C. Tschierske (TP 2) while the polymeric polyphiles will be obtained from the group Kreßler (TP 3). Investigations on the lyotropic behaviour and their aggregation in water will be carried out first. Thereby influence of the chemical structure of the side chains as well as the block sequence will be studied followed by investigations of the surface activity of the compounds at the air-water interface. Lipid model membranes and lipid monolayers will serve as templates for the binding of the polyphiles and resulting structure formation at the interface. The binding strength is due to hydrophobic and hydrophilic interactions with the membranes and will be varied by changing the chemical structure of the polyphiles. The basic methods for studying the aggregation behaviour are light scattering methods, transmission electron microscopy, isothermal titration calorimetry (ITC) for the determination of the critical micellar concentration (cmc), as well as monolayer methods (epi-fluorescence-spectroscopy, infrared-reflection-absorptionspectroscopy (IRRAS) Brewster-angle-microscopy). Studies on the interaction of polyphiles with lipid bilayers and lipid monolayers will be carried out in a parallel fashion. Goal of studies with the low molecular weight polyphiles is to modify the interactions of these molecules and the resulting structure formation and segregation in or at the membranes by changes in the lateral chain structure. For polymeric polyphiles possible chiral recognition between polymers and chiral lipids plays an important addional role. For these studies thermal methods such as ITC and DSC will be used as well as spectroscopic methods such as FT-IR-Spectroscopy on solid supported membranes (FT-IR-ATR) and FT-IRRAS on lipid monolayers. In cooperation with the group Bacia (TP 6) CLSM studies on GUVs will be performed coupled with dye efflux measurements. Similar dye release experiments with small vesicles will also be carried out to elucidate the integrity of the permeation barrier of the membrane after incorporation of polyphiles. In close cooperation with the group Saalwächter (TP 5) additional NMR-experiments will be carried out with the same systems.