Inclusions induced phase separation in mixed lipid film

The effect of rigid inclusions on the phase behavior of a film containing a mixture of lipid molecules is investigated. In the proposed model the incl usion-induced deformation of the film, and the resulting energy cost are st rongly dependent upon the spontaneous curvature of the mixed film. The spon taneous curvature is in turn strongly influenced by the composition of film . This coupling between the film composition and the energy per inclusion l eads to a lateral modulation of the composition, which follows time local c urvature of the membrane. In particular, it is shown that inclusions may in duce a global phase separation in a film which would otherwise be homogeneo usly mixed. The mixed film is then composed of patches of different average composition, separated by the inclusions. This process may be of relevance to explain some aspects of lipid-protein association in biological membran es.