PERMEABILITY CHARACTERISTICS OF LIPOSOMES IN A NET - MEMBRANES OF DIHEXADECYL PHOSPHATE WITH POLYMERIZABLE GEGENIONS

The sonication of hydrated bilayers of choline methacrylate dihexadecyl phosphate (1) produces small vesicles (90-nm diameter) with a lipid-phase transition at 37 degree C. The vesicles are readily photopolymerized by irradiation of the 209-nm absorption band. Both the unpolymerized and the polymerized vesicles of 1 entrap the water-soluble marker left bracket **3H right bracket glucose. The light-induced polymerization increased the temperature of the lipid-phase transition and decreased the membrane permeability to left bracket **3H right bracket glucose by a factor of 4. 6. The absorption spectra and phase-transition behavior indicate that the hydrophobic chromophore at one end of the water-soluble monomeric gegenion, choline methacrylate, penetrates into the bilayer of dihexadecyl phosphates. Unpolymerized and polymerized unsymmetrical vesicles successfully entrapped left bracket **3H right bracket glucose. The left bracket **3H right bracket glucose permeability of outside membranes was reduced by a factor of 3. 4 by polymerization but was not altered significantly for the inside membranes. This suggests that the vesicle permeability is primarily controlled by the outside leaflet of the bilayer of DHP membranes.