Torchilin V P, Trubetskoy V S, Whiteman K R, Caliceti P, Ferruti P, Veronese F M
Department of Radiology, Massachusetts General Hospital, Charlestown, USA.
J Pharm Sci. 1995 Sep;84(9):1049-53. doi: 10.1002/jps.2600840904.
Carboxy group-terminated synthetic polymers--branched poly(ethylene glycol), poly(acryloylmorpholine), and poly(vinylpyrrolidone)--were made amphiphilic by derivatization with phosphatidyl ethanolamine via the terminal carboxy group and then incorporated into lecithin-cholesterol liposomes prepared by the detergent dialysis method. Following the biodistribution of liposomes in mice, all three polymers were shown to be effective steric protectors for liposomes and were able to sharply increase liposome circulation times in a concentration-dependent manner. The accumulation of liposomes in the liver decreases. The effects observed are similar to those found for liposomes modified with linear poly(ethylene glycol). At low polymer concentration, amphiphilic branched poly(ethylene glycol) seems to be the most effective liposome protector, most probably, because at the same molar content of anchoring groups, each attachment point carries two polymeric chains and doubles the quantity of liposome-grafted polymer comparing to linear poly(ethylene glycol).
羧基封端的合成聚合物——支化聚乙二醇、聚（丙烯酰吗啉）和聚（乙烯基吡咯烷酮）——通过末端羧基与磷脂酰乙醇胺衍生化而变得具有两亲性，然后被整合到通过去污剂透析法制备的卵磷脂-胆固醇脂质体中。在小鼠体内进行脂质体的生物分布研究后，所有这三种聚合物都被证明是脂质体有效的空间保护剂，并且能够以浓度依赖的方式显著增加脂质体的循环时间。脂质体在肝脏中的积累减少。观察到的效果与用线性聚乙二醇修饰的脂质体相似。在低聚合物浓度下，两亲性支化聚乙二醇似乎是最有效的脂质体保护剂，很可能是因为在相同摩尔含量的锚定基团下，每个连接点携带两条聚合物链，与线性聚乙二醇相比，脂质体接枝聚合物的量增加了一倍。
