Pva Modified Liposomes

Liposomes are lipids suspended in water with spherical self-enclosed system, which have bilayer structures and an inner aqueous phase. Because liposomes posses a lot of advantages,such as biocompatibility, the ability to encapsulate bothwater-soluble and lipid-soluble molecules, biodegradability and the ability to delivery drugs to specific target sites, so thon are currently being used as a drug delivery carrier for the sustained release of a drug compound to a specific site in the body.There are many problems need to be resolved urgently for the application of liposomes, for example, the preparation of the raw materials and the stability of liposomes. Therefore, the purpose of this dissertation is to solve the above problems, and make the liposomes modified by poly vinyl acohol.In this dissertation, a method, combined supercritical carbon dioxide extraction and solvent extraction, is chosen to prepare high-purity soybean phosphatidylcholines(SPC) which is liposomal membrane material from soybean phospholipids. The product containing 93.98 wt% phosphatidylcholines (PC) is analyzed by HPLC. SPC can be degraded because of its peroxidation. The effect of some antioxidants such as V_e ,BHT and V_c on the prevention of SPC peroxidation are studied. V_e and BHT are chosen as antioxidants in liposomes.A novel liposome modified with polyvinyl alcohol (PVA) was prepared by the method in which lipsomes were formed through two steps of emulsification and dispersion. First, SPC was dissolved in organic solvent, then added the aqueous solution of entrapped material, and this mixture was emulsified by ultrasonic emulsion to form w/o type emulsion. The product was then immediately added to PVA solution to form a w/o/w type emulsion. Finally removed the organic solvent from generate liposomes. The second emulsification and the process of removing the organic solvent will influence the properties of liposomes. The liposome entrapment efficiency decreased as the increased temperature during the second emulsification. High entrapment efficiency, larger amount of adsorption of PVA and smaller size were obtained when the second emulsification was performed at long ultrasonic emulsion time, but the liposomes would broken at longer time of ultrasonic. And smaller liposome particles were obtained when the organic solvent evaporation at a lower temperatureThree kinds of PVA with different degree of hydrolysis were chosen to prepared liposomes. The results showed that adsorption amount of liposomes decrease as the...