Liposomes incorporating cinnamoyl gelatin and cinnnamoyl alginate and their pH and UV-responsive release property

Abstract

pH and UV-responsive liposome was prepared by decorating the surface of egg phosphatidylcholine (EPC) liposome using cinnamoyl gelatin (CinGel) and cinnamoyl alginate (CinAlg). CinGel and CinAlg were prepared through condensation reaction between cinnamoyl chloride and each polymer. Liposomes bearing CinGel/CinAlg were prepared by a film hydration method while CinGel/CinAlg mass ratio was kept to be 7:3. The fluorescence quenching of carboxyfluorescein (CF) encapsulated in the liposome and the diameter of the liposomes decreased as the EPC to cinnamoyl polymer mass ratio increased. Liposome without cinnamoyl polymers hardly released its payload for 120 sec at all the pH values tested (pH 5.0, pH 6.0, pH 7.4, and pH 9.0). Meanwhile, liposome with CinGel/CinAlg released its payload markedly at pH 5.0 and pH 6.0. The complex coacervation was thought to cause the release of dye out of the liposomes. Liposome scarcely released its payload at pH 7.4 for 120 min without UV irradiation regardless of whether it included the cinnamoyl polymers. Meanwhile, liposome with cinnamoyl polymers showed marked release under UV irradiation.