Dynamics of biological membranes: Quasi elastic neutron scattering studies of model membranes

Real biological membranes are complex multi-component systems which are not easily subjected to systematic investigations, although e.g. the dynamics of light-induced structural reorganizations of thylakoid membranes in chloroplast organelles have been studied using time-resolved small-angle neutron scattering [1]. The complementary approach to the study of real membranes is the study of phospholipid model membranes with full control of lipid species together with the type and concentration of any other molecule embedded in the membrane and with a certain control over the large scale membrane organization. Adding a series of 1-alcohols to DMPC membranes changes membrane structural properties such as bilayer thickness and lipid packing. We have performed quasi elastic neutron scattering in the picosecond to nanosecond time range in order to investigate the influence of membrane architecture and membrane doping on the nanoscopic dynamics of phospholipids in multilamellar and unilamellar vesicles in excess water. These results together with structural characterization will be discussed.