Effect of surfactants on the stability of modified egg-yolk phosphatidyl choline liposomes

Disintegration by surfactants on egg-yolk phosphatidyl choline (PC) vesicles, stabilized with polycholesteryl methacrylate and carboxy methyl chitosan, was investigated by measuring the amount of marker dye (bromothymol blue) released from the vesicles. In all the studies at pH 7.4 anionic and nonionic surfactants caused vesicle disintegration at low concentrations while cationic surfactants produced breakdown of vesicles at high concentrations. It was found that the modified liposomes disintegrated in the following order: Polymeric liposomes less than carboxymethyl chitosan coated/stearic acid/oleic acid containing PC liposomes less than cholesteryl methacrylate monomer containing PC liposomes/PC liposomes Polymeric liposomes were found to be the most stable compared with all other types. This may be explained due to the filling of the pores in the lipid structure which in turn block the surfactant penetration into phospholipid bilayers. In contrast to unsaturated fatty acid (oleic acid) saturated fatty acid (stearic acid) containing liposomes are more stable.