Lecithin Liposomes Quantitative Structure-function Relationship Studies

Liposomes are microscopic spherical vesicles that encapsulated part of the water phase that are formed when phospholipids are dispersed in water,because the structure of liposomes is similar to biomembrane, it is usually named as the artificial membrane.Liposomes are widely used as drug carrier because liposomes have many advantage such as inprove the stability of the drug that, prolonging and targeting ralease of therapeutic agent,minimizing clinical drug dose and reducing toxicity effects. the liposomes is a liquid suspension, during storage prone toLiposomes may aggregation, integration, and lead to the leakage of encapsulated drug during storage. Therefore it is necessary to study of the factorsthat affect the stability of liposomes Systematically.Phospholipids are the major membrane lipid, phosphatidylcholine, especially the most commonly used, phosphatidylcholine can be divided into different categories according to the fatty acid chain, This paper prepared liposomes with phosphatidylcholine of Different structures to accomplish the following research:(1) Optimizing the preparation process: Choose the Tartrate Indoquinoline as water-soluble model drug, preparation the liposomes of Tartrate Indoquinoline by the Reverse-Phase evaporation method. Entrapment efficiency was determined after the separation of the unentrapped drug by Sephadex-G50 chromatography., using Box-Behnken response surface curve method to determine the best preparation process of liposomes use the The encapsulation efficiency and particle size as an indicator, results showed that the encapsulation efficiency of prepared liposomes was 44.34%, and maximum encapsulation efficiency that calculated by the software of Box-Behnken response surface curve is 44.68%.(2) This charpter is to study the to differences of the stability of liposomes prepared with phosphatidylcholine of different fatty acid. Preparing Tartrate Indoquinoline liposomes by Optimized preparation process with 1,2-dimyristoyl-sn-glycerol-3-phosphatidyllcholines, 1,2-dipalmitoyl-sn-glycerol-3-phosphatidyllcholines, 1,2-disteraroyl-sn-glycerol-3-phosphatidyllcholines and 1,2-dioleoyl-sn-glycerol-3-phosphatidyllcholines. By comparing the stability parameters of the prepared liposomes. we found that the particle size of liposomes prepared is positively correlated to the fatty acid chain length of phosphatidyllcholines and negative correlated to the degree of unsaturation to the fatty acid chain of phosphatidyllcholines; the hydrolysis rate of liposome is negatively correlated to the fatty acid chain length of phosphatidyllcholines and positively correlated to the degree of unsaturation to the fatty acid chain length of phosphatidyllcholines.(3) Research the activation energy of cohesion of Prepared liposomes and compare the stability of liposomes by activation energy. Advance the relationship between the stability index of liposomes of water-soluble drugs and he fatty acid chains of phosphatidylcholine based on the data obtained above, calculated the stability of liposomes and the results are Consistent with the results determined by activation energy. Indicates that the relationship can be used to determine the stability of liposomes prepared with different phosphatidylcholine.