The Application Research Of Soybean Phosphatidylethanolamine-Methoxy Polyethylene Glycol 2000

Phosphatidylethanolamine-poly(ethylene glycol)is a kind of amphiphilic block copolymers that possesses excellent cycling stability and good biological compatibility,thus it has been widely used in the preparation of liposomes,microemulsion and etc.Nevertheless,the high cost of phosphatidylethanolamine-poly(ethylene glycol)is a major drawback for its practical applications.At this point,Soybean phosphatidylethanolamine-methoxy polyethylene glycol 2000(SPE-MPEG2000)can be obtained by soybean lecithin and MPEG2000,as a derivative of them.Furthermore,SPE-MPEG2000 should go far towards solving this problem.Therefore,in this paper,SPE-MPEG2000 were synthesized and its application were studied in the preparation of liposomes.SPE-MPEG2000 was prepared through a series of experimental procedures such as oxidation,acylation,amidation and etc.During the processes,soybean lecithin and MPEG2000 were used as raw materials.Moreover,the product structure was characterized by NMR,IR,GPC.Using calcein as a small molecule water-soluble model drug,liposomes with or without SPE-MPEG2000 were prepared by thin film dispersed method.The effect of SPE-MPEG2000 on liposomes stabilities was evaluated by comparing their form,particle size and its distribution,zeta potential,the influence of ethanol solution added on absorbance of liposomes and encapsulation efficiency of entrapped calcein.Notably,the liposomes prepared with SPE-MPEG2000(sterically stabilized liposomes,SSL)were globular in appearance compared to another liposomes(conventional liposomes,CLs)in TEM,it was distributed uniformly and dispersed well.The particle size distribution of the two liposomes was more concentrated and showed an unimodal normal distribution.The mean diameter of SSL was approximately(178.3± 1.8)nm,which is smalller than that of CLs's((196.4±2.1)nm).After storing at 4 ? for 30 days,the particle size distribution of the two liposomes was widened and the particle size was increased.The mean diameter of CLs was about(269.4±1.9)nm,which was increased by 37.17%than the initial CLs.However,the mean diameter of SSL was about(197.7±2.0)nm,which was increased by only 10.88%than the initial SSL.The absorbance of SSL remained little change after adding ethanol solution.Thus it can indicate that SSL was more stable than CLs during placement.The encapsulation efficiency of the entrapped contents of SSL(8.23%,n=3)was higher than CLs(4.78%,n=3).Based on the above discussion,SPE-MPEG2000 has a good stabilizing effect on water-soluble model drug liposomes.Using praziquantel as a small molecule fat-soluble model drug,liposomes were prepared with SPE-MPEG2000(PZQ-SSL)and without SPE-MPEG2000(PZQ-CLs)through thin film dispersed method.The effect of SPE-MPEG2000 on liposomes stabilities was evaluated by comparing their form,particle size and its distribution,zeta potential,surface hydration layer thickness(FALT)and encapsulation efficiency of entrapped praziquantel.From TEM,it presented that PZQ-SSL with globular architecture was distributed evenly and dispersed well than PZQ-CLs.The mean diameter of PZQ-SSL was approximately(94.81±0.87)nm,which is smalller than that of PZQ-CLs's((110.80± 1.12)nm).The FALT of PZQ-SSL was approximately(2.50±0.03)nm,which is slightly higher than that of PZQ-CLs's((1.12±0.02)nm).Thus the results show that SPE-MPEG2000 has a good stabilizing effect on fat-soluble model drug liposomes.Therefore,SPE-MPEG2000 could meet the needs of liposomes sterically stabilized membrane materials.