Budding, fission and domain formation in mixed lipid vesicles induced by lateral phase separation and macromolecular condensation.

Phase separation in vesicles of lipid mixtures creates an entirely new variety of shapes. The process may be described in terms of a combination of the theory of spinodal decomposition and the membrane bending energy concept. One major aspect discussed is the stabilization of domain structures in intrinsically unstable (phase segregated) states by the coupling between local bending and phase separation. A second topic is the role of interfacial tension for the stability of the domains. We show that vesicle fission is a consequence (1) of the reduction of the interfacial chemical energy or (2) of local phase separation within the neck connecting bud and mother vesicle. Finally, the formation of coated buds in giant vesicles caused by the lateral condensation of membrane-bound macromolecular amphiphiles is described.