SPECIFIC INTERACTION BETWEEN WATER-SOLUBLE PHOSPHOLIPID POLYMER AND LIPOSOME

A water-soluble polymer having both a phospholipid polar group and an azobenzene group, poly(2-methacryloyloxyethyl phosphorylcholine-co-p-phenylazoacrylanilide) (poly(MPC-co-PAAn) was synthesized and the interaction between the liposome of the phospholipid was investigated in comparison with other water-soluble azoaromatic polymers. When the poly(MPC-co-PAAn) was incubated with dipalmitoylphosphatidylcholine (DPPC) liposomes above these gel-liquid crystalline temperatures, an electronic spectrum of azobenzene moiety, which is a hydrophobic probe, showed that the a copolymer chain exists under nonpolar circumstances. Thus, poly(MPC-co-PAAn) interacts with DPPC liposomes. On the other hand, other copolymers do not interact with the liposomes. Moreover, heat of the gel-liquid crystalline transition of DPPC liposomes was increased by the presence of poly(MPC-co-PAAn). These findings clearly indicate that the poly(MPC-co-PAAn) has an affinity to the DPPC liposomes and hybridizes with liposomes based on the phospholipid polar group of the copolymer.