目的:制备叶酸修饰的pH响应型阿霉素脂质体(FRLD),并对其理化性质进行评价.方法:采用硫酸铵梯度法制备FRLD,以包封率为指标运用正交设计法进行制备工艺的优化;用CL-4B琼脂糖凝胶柱分离-高效液相色谱法测定FRLD的包封率;运用粒径电位分析仪测定脂质体的平均粒径及Zeta电位,透射电镜观察脂质体的形态;运用动态透析法考察FRLD在不同pH环境中的药物释放情况,并考察FRLD在不同pH环境(pH 7.4和5.5)37℃水浴中的粒径随时间的变化情况.结果:制得的FRLD为圆形或类圆形的大单室脂质体,平均粒径(153.8±2.62) nm,Zeta电位为(-24.62±2.28)mV,平均包封率为89.45％.FRLD在pH 7.4的中性环境中,药物释放缓慢,24 h累积释放5.5％,而在pH 5.5的酸性环境中,药物释放显著加快,24 h累计释放率均达到90.8％,表现出非常强的pH敏感性能.FRLD在pH 7.4的中性环境中粒径保持稳定,而在pH 5.5的酸性环境中,粒径随孵育时间显著增加,脂质体发生融合.结论:采用硫酸铵梯度法制备的FRLD,能获得较高的包封率,并具有良好的pH响应性能.%Objective:To prepare and characterize folate-decorated pH-responsive doxorubicin liposomes (FRLD) and evaluate their quality.Methods:FRLD were prepared by the ammonium sulfate gradient method.Taking entrapment efficiency as an index,the technical conditions were optimized by orthogonal test.Unloaded doxorubicin was separated from the liposomes by sepharose CL-4B chromatography and HPLC method was used to determine the entrapment efficiency of FRLD.The shape,particle size and zeta-potential of FRLD were investigated by transmission electron microscope and laser scatter.The drug release from liposomes in PBS (pH 7.4 and pH 5.5) was monitored by dialysis method.The change of particle size of FRLD over time was monitored in PBS of different pH values at 37 ℃.Results:The obtained FRLD were round and large unilamellar vesicles with average size of (153.8 ± 2.62) nm,zeta potential of-(24.62 ± 2.28) mV and entrapment efficiency of 89.45％.The results of drug release test showed that FRLD exhibited minimal DOX leakage in pH 7.4 PBS after 24 h incubation,and more than 90％ of the encapsulated DOX still retained in the liposomes.While in pH 5.5 PBS,FRLD released more than 90％ DOX after 24 h incubation and showed stronger pH response.And furthermore,the mean diameter of FRLD was significantly increased at low pH (5.5) at 37 ℃,which indicated vesicle aggregation and membrane fusion.Conclusion:FRLD prepared by the ammonium sulfate gradient method can achieve high entrapment efficiency and remarkable pH response.
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