Microdomain formation in model biomembranes

We have investigated the microdomain formation in small unilamellar vesicles (SUVs) composed of ternary mixture of deuterated DPPC, hydrogenated DOPC and hydrogenated cholesterol using a contrast matching technique of small angle neutron scattering. Above the miscibility temperature we cannot observe the scattering intensity from the SUVs. Thus, DPPC, DOPC and cholesterol are mixed at the molecular level in membranes. However, below the miscibility temperature we observe characteristic scattering profiles with a scattering maximum, which clearly shows that the lateral segregation of lipids takes place. The observed profiles are well described by a model scattering function for a single hemispherical shape domain with the radius of several nm. With decreasing the temperature the scattering intensity increases with keeping their maximum positions, indicating that the domain composition strongly depends on the temperature