Evaluation of in vitro stability of small unilamellar vesicles coated withcollagen and chitosan

To improve the in vitro stability of small unilamellar vesicles (SUV), the permeability of SUV, made from soyabean phosphatidylcholine (PC) and coated with collagen and chitosan, was studied using 5(6)-carboxyfluorescein (5(6 )-CF) as a fluorescence probe. The results showed that the coating with a c ollagen/PC weight ratio of 2, or a chitosan/PC weight ratio of 8, significa ntly decreased the permeability of liposomal membranes. In addition, the fl uorescence polarization method was used to study the influence of a coating with collagen and chitosan at the above ratios on the fluidity of liposoma l membranes, employing an intramolecular charge transfer compound, a 3-meth oxy-4'-N,N-dimethylaminoflavone derivative (DMMF), as a fluorescence probe. The fluidity of a liposomal membrane coated with either of the two macromo lecules showed no obvious changes, indicating that SUV coated with collagen and chitosan at appropriate weight ratios, can significantly improve the i n vitro stability of liposomal membranes without disturbing their fluidity. (C) 1999 Society of Chemical Industry.