Dynamic Studies of the Adhesion, Deformation and Fusion of Monolayers, Bilayers and Membranes

9305868 Israelachvili This project continues the investigation of the roles of different interbilayer forces and bilayers fluidity on the molecular-scale deformations of adhering and fusing bilayers using novel electron and atomic force microscopy and surface force measurements. Past experiments identified a particularly important role for hydrophobic forces in adhesion and fusion. In this follow-up project, a variety of techniques are used to study the dynamics of surfactants, lipids and domains (lateral diffusion, overturning or 'flip-flop', and exchange) during nonequilibrium interactions such as adhesion, fusion and membrane structural transitions. The aim is to asess how these dynamic processes and their rates - in contrast to equilibrium properties - affect structural changes, adhesion and fusion. The investigators will attempt to achieve similarly high time and spatial resolution of ionic effects on membrane interactions by using 'cages' calcium compounds to liberate divalent ions at a specific time and place. Complementary surface force apparatus and cyro-electron microscopy measurements will be made how calcium induces membrance structural changes, adhesion and fusion with millisecond time resolution. Additional structural information will be provided at the sub-molecular scale by studying the effects of divalent ions on simple Langmuir- Blodgett membranes using the atomic force microscope.