| Summary: | In order to study lipid membrane properties, fluorescence solvent relaxation method, which enables us to determine the degree of hydration of the membrane and the mobility of the hydrated lipid molecules, was used. Applying three different naphthalene derivatives as fluorescent dyes (Patman, Laurdan and Prodan) allowed probing different parts of the headgroup region of the bilayer. First, wavelength-dependent parallax quenching measurements resulted in the determination of precise locations of Laurdan and Patmant within the DOPC bilayer. Exploring the issue of the probes locations within the lipid bilayer, acrylamide quenching experiments were performed. They have shown Patman relocalization in cationic, DOTAP-containing systems. Bilayers formed from phosphatidylcholines with different alkyl chains (DOPC, POPC, OPPC and PCΔ6) but the same polar head were also studied. The results have shown differences in the both hydration and mobility of the membranes depending on the type of fatty acid chains of bilayer lipids. Finally, liposomes formed from cationic lipids, commonly used to deliver genes into cells in vitro and in vivo, were investigated. Measurements of the structure and dynamics of fully hydrated liquid crystalline lipid bilayers composed of the mixtures of cationic DOTAP and neutral DOPC...
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