Sans Study of the Unilamellar DMPC Vesicles. the Fluctuation Model of Lipid Bilayer

Abstract

On the basis of the separated form-factors model, parameters of the polydispersed unilamellar DMPC vesicle population are analyzed. The neutron scattering length density across the membrane is simulated on the basis of fluctuated model of lipid bilayer. The hydration of vesicle is described by sigmoid distribution function of the water molecules. The results of fitting of the experimental data obtained at the small angle spectrometer SANS-I, PSI (Switzerland) are: average vesicle radius 272 angstrom, polydispersity of the radius 27%, membrane thickness 50.6 angstrom, thickness of hydrocarbon chain region 21.4 angstrom, number of water molecules located per lipid molecule 13, and DMPC surface area 59. The calculated water distribution function across the bilayer directly explains why lipid membrane is easy penetrated by water molecules.