Factors influencing the physicochemical characteristics of cationic polymer-coated liposomes prepared by high-pressure homogenization

Nano-liposomes were prepared by the modified reverse phase evaporation method using high-speed and high-pressure homogenizers. The optimal conditions for preparation of non-coated liposome, chitosan-coated liposome, and eudragit EPO-coated liposome were investigated. The liposomal membrane was composed of soybean lecithin. Chitosan and eudragit EPO coated the external surface of liposomes by electrostatic interaction. The results show that the physicochemical properties (e.g., mean size, polydispersity index, surface charge, and encapsulation efficiency) of non-coated liposomes were affected by homogenization pressure, number of homogenizing cycles, and ratio of core material to lecithin. Chitosan coating increased the mean size of liposome. In the case of eudragit EPO coating, the mean size of liposome increased up to 0.2%; a further increase in the eudragit EPO concentration led to some changes of the mean size of eudragit EPO-coated liposome. The highest stability for 30 day was achieved with 0.3% chitosan-coated liposome and 0.3% eudragit EPO-coated liposome, respectively. The release property was influenced by the type of coating material; the chitosan and eudragit EPO coating layers on the non-coated liposome surface delayed the release of the core material. Overall, a core material to lecithin ratio of 1:3 and three homogenizing cycles under 1000 bar were selected as the optimal processing conditions. In addition, 0.3% eudragit EPO-coated liposome was selected as the optimal coating.