麦胚凝集素修饰延缓脂质体眼部消除

Modification by wheat germ agglutinin delays the ocular elimination of liposome

本文旨在探讨麦胚凝集素(wheat germ agglutinins,WGA)修饰的脂质体作为眼部药物递送载体的可行性。采用成膜水化法制备包载5-羧基荧光素(5-carboxyfluorescein,FAM)的脂质体(liposome loaded with FAM,LS/FAM),将巯基化的WGA经聚乙二醇桥联修饰于该脂质体表面(WGA-modified liposome loaded with FAM,WGA-LS/FAM)。测定WGA的巯基化程度,考察其修饰到脂质体表面后的生物活性,并对WGA-LS/FAM的理化性质和眼部生物黏附性能进行表征和评价。所得巯基化WGA每分子中含1.32个巯基。WGA-LS/FAM的平均粒径为(97.40±1.39)nm,多分散系数为0.23±0.01,FAM的包封率为(2.95±0.21)%,体外24 h的渗漏率约为4%。红细胞凝集实验表明,修饰到脂质体表面的WGA仍保持其糖蛋白结合活性。脂质体在大鼠眼部的消除过程符合一级动力学特征,WGA-LS/FAM的消除速率显著低于未经修饰的脂质体,表现出适合眼部给药的生物黏附特性。

The purpose of this study is to explore the feasibility of wheat germ agglutinin （WGA） modified liposome as a vehicle for ophthalmic administration. Liposome loaded with 5-carboxyfluorescein （FAM） was prepared by lipid film hydration method. WGA was thiolated and then conjugated to the surface of the liposome via polyethylene glycol linker to constitute the WGA-modified and FAM-loaded liposome （WGA-LS/FAM）. The amount of thiol groups on each WGA molecule was determined, and the bioactivity of WGA was estimated after it was modified to the surface of liposome. The physical and chemical features of the WGA-modified liposome were characterized and the ocular bioadhesive performance was evaluated in rats. The result showed that each thiolated WGA molecule was conjugated with 1.32 thiol groups. WGA-LS/FAM had a mean size of （97.40 ± 1.39） nm, with a polydispersity index of 0.23 ± 0.01. The entrapment efficacy of FAM was about （2.95 ± 0.21） %, and only 4% of FAM leaked out of the liposome in 24 h. Erythrocyte agglutination test indicated that after modification WGA preserved the binding activity to glycoprotein. The in vivo ocular elimination of WGA-LS/FAM fitted first-order kinetics, and the elimination rate was significantly slower than that of the unmodified liposome, demonstrating WGA-modified liposome is bioadhesive and suitable for ophthalmic administration.