修饰脂质体的可断裂聚乙二醇脂质衍生物的研究进展

聚乙二醇脂质衍生物可增加脂质体的稳定性，延长其体内循环时间。传统的长循环材料由于连接聚乙二醇与脂质的化学键太稳定，导致脂质体内容物释放延迟而影响药效。近年来提出可断裂聚乙二醇脂质衍生物的概念，该类衍生物具有可以在人的生理或病理条件下断裂的性质，能够延长脂质体体内循环时间，在到达靶部位后由于聚乙二醇已经从脂质体表面脱落，脂质体可以与病变细胞结合，从而将药物送入细胞。本文综述了可断裂聚乙二醇脂质衍生物的种类、断裂类型、在脂质体中的应用概况及在应用中的优势和局限。

Recent advances in the study of cleavable PEG-lipid derivatives modifying liposomes

Polyethylene glycol(PEG) lipid derivatives could increase the stability of liposomes in vivo and in vitro and prolong the circulation time of liposomes in vivo.However,the chemical bond between PEG and lipid was so stable that liposomes modified with traditional PEG-lipid derivatives could not release their contents at targeted tissue immediately and the pharmacodynamic effect was reduced.The concept of cleavable PEG-lipid was raised in recent years and these PEG-lipid derivatives could break under physiological or pathological condition.The cleavable PEG-lipid derivatives could prolong the circulation time of liposomes,and after arriving at targeted location,PEG fragment had cleaved from the surface of liposomes,so liposomes could bind with pathological cells and release contents into cells.Removal of the protective polymer layer is necessary once the liposome close to the tumour to allow to fuse and release drug.Attempts have been made to increase the circulation time and reconstitute the cellular affinity of liposomes by incorporating PEG-lipid derivatives.This review focused on the kinds of cleavable PEG-lipid derivatives,types of cleavage,the application feature to liposomes and the advantages and localizations.