Complexes of Negatively Charged Liposomes with Chitosan: Effect of Phase State of the Lipid Bilayer

Interaction of the cationic polymer chitosan with anionic liposomes has been studied. The characteristics of the polycation-liposome complex have been determined by the phase state of the lipid membrane. Chitosan adsorbed on the surface of liquid liposomes has induced transmembrane migration of anionic lipid from the inner to the outer leaflet. Liquid liposomes have retained their integrity in the complex with chitosan. The adsorbed polymer can be completely removed from the membrane by the addition of a low-molecular electrolyte. The chitosan adsorption on the surface of solid liposomes has led to the formation of defects in the membrane: in this case the polycation adsorption has been irreversible. The established phenomena may be important for the understanding of biological effects of chitosan.