Preliminary Study On Cationic Liposome As Gene Carrier

In order to prepare gene carrier with high transfection efficiency and low cytotoxicity, Non-magnetic and magnetic cationic liposome as gene carrier had been preliminarily investigated in this dissertation.Transfection efficiency and cytotoxicity of cationic liposome mainly depend on cationic lipid. Three cationic lipids CA-Lys, CA-Lys-Lys₂ and OA-Lys had been successfully synthesized with BOP as coupling reagent and column chromatographer to purify products. 1HNMR and MS analysis showed that molecular structure of products were consistent with that of target molecules.A series of cationic liposomes and magnetic cationic liposomes had been prepared with CA-Lys,CA-Lys-Lys₂ and OA-Lys , and their morphology , particle diameter, Zeta potential, interaction with DNA and cytotoxicity were tested. TEM and particle diameter analysis showed that all the cationic liposomes and magnetic cationic liposomes were sphere in morphology and 110-140nm in size. Addition of CA-Lys,CA-Lys-Lys₂ and OA-Lys could make the surface of liposomes positive. Gel electrophoresis analysis showed that CA-Lys and OA-Lys cationic liposome could complex with DNA at N/P 5:1,but not completely, while CA-Lys-Lys₂ cationic liposome could complex with DNA at N/P 2:1. Low cytotoxicity of CA-Lys,CA-Lys-Lys₂ and OA-Lys had been confirmed by MTT.Cytotoxicity of cationic liposome is mainly engendered by cationic lipid. To reduce cytotoxicity , another kind of cationic liposomes and magnetic cationic liposomes had been prepared by surface modification of neutral liposome and magnetic liposome with CS, OCM-CS, 16-CS, Lys-CS. After modification, diameter of liposome and magnetic liposome increased and surface charge become positve from negtive. CS, OCM-CS and 16-CS cationic liposome could complex with DNA at 10:1(mass ratio), while Lys-CS cationic liposome could complex with DNA at 2:1. MTT assay showed that CS, OCM-CS, 16-CS, Lys-CS could reduce cytotoxicity of liposome.In sum, some gene carriers with high transfection efficiency and low cytotoxicity may be found out from the Non-magnetic and magnetic cationic liposomes prepared in this dissertation.