制备维生素C 脂质体，并考察其包封率的影响因素。采用pH 梯度法制备维生素C 脂质体，以紫外分光光度法和粒度仪分别测定脂质体的包封率和粒径，并考察外水相pH、超声时间、载药温度及药脂比对包封率的影响。结果显示包封率随外水相pH 的降低而增加，最佳超声时间为15 min，随着载药温度的增加包封率有提高的趋势，最佳药脂比为1∶5。该条件下pH梯度法制备的维生素C 脂质体的包封率为（49.79±1.6）%（n=3），平均粒径为（118.3±9.6）nm。

Vitamin C liposomes were prepared by the pH gradient method. The entrapment efficiency and the size of vitamin C liposomes were detected by UV-visible spectrophotometry and particle analyzer, respectively. Effects of various factors on the entrapment efficiency including exterior pH, ultrasonic time, incubation temperature and the ratio of drug to lipid, were investigated. The results showed that the entrapment efficiency increased with the decrease of pH and increase
of incubation temperature., The optimal ultrasonic time and ratio of drug to drug was 15 min and 1∶5. The entrapment efficiency of vitamin C liposomes under the optimized conditions was 49.8% and the mean diameter was 118.3 nm.