[Acid-sensitive liposomes prepared with poly(ethylene glycol)-POPA derivatives]

The poly(ethylene glycol)-lipid derivatives were synthesized for constructing pH-sensitive liposomes. The polyethylene glycol polymer MePEG2000-NH2 and phospholipids POPA were connected by phosphorus-amide linkage. The poly(ethylene glycol)-lipid derivatives acidic sensitive liposomes were prepared. Factor effects on polymer insertion into liposomes were evaluated and the pH-sensitivity of the polymer associated liposomes were studied by calcein release assay. The poly(ethylene glycol)-lipid derivatives acidic sensitive liposomes were prepared successfully by the extruding linkage device. The liposomes constructing by poly(ethylene glycol)-lipid derivatives was stable at pH 6.5-7.5, the stability was closely related to phospholipid types and cholesterol content of the preparation of liposomes. At pH 5.0 occurred when divulging fluorescence occurred obviously, the leakage rate and the strength was with a positive correlation between time of in the acidic environment and intensity of acid. The acidic sensitive liposomes prepared by poly(ethylene glycol)-lipid derivatives were developed as a potential pH sensitive delivery system.