Sulfated N-Myristoyl Chitosan as a Surface Modifier of Liposomes

Sulfated N-myristoyl chitosan (S-M-chitosan), which is strongly electrolytic and water soluble as well as partly hydrophobic due to long alkyl chains, was synthesized to be used as a liposome-surface modifier. The effects of the treatment with an aqueous S-M-chitosan solution on the stability of the liposome suspension prepared from hydrogenated egg yolk lecithin were examined on several points. A suspension of large liposomes prepared by the Bangham method was precipitated by standing for a day, but the precipitation was restrained when the sample was treated with S-M-chitosan solution. The turbidity of a small liposome suspension was changed greatly after the suspension was freeze-thawed, but the change was small in the treated sample. A similar result was obtained when the suspension was freeze-dried following the addition of water. These results come from the facts that the surface of the liposome was coated with S-M-chitosan and negatively charged as ascertained by the measurement of zeta potential a...