目的 制备氧氟沙星脂质体以增加细菌对药物的敏感性，并对其进行体外评价。方法 以磷脂和胆固醇为材料，以pH梯度法制备氧氟沙星脂质体；考察pH值，水浴温度和时间对脂质体包封率的影响。测定脂质体的粒径并进行电镜观察；以生理盐水为介质考察脂质体的体外释放；使用纸片扩散法和稀释法测定氧氟沙星脂质体和溶液对金黄色葡萄球菌的抑菌效果。结果 当pH值为7.0，水浴温度为50 ℃，水浴时间为5 min时，脂质体的包封率最高，为82.40%。氧氟沙星脂质体的平均粒径为174 nm，电镜下形态良好。脂质体在体外具有缓慢释放氧氟沙星的性质。氧氟沙星脂质体和溶液以纸片扩散法测定的抑菌圈直径相同，而以稀释法测定的最低抑菌浓度分别为0.39和0.78 μg·mL^-1。结论 pH梯度法可制备包封率较高的氧氟沙星脂质体；氧氟沙星装载于脂质体后可增加对金黄色葡萄球菌的敏感性。

OBJECTIVE To prepare ofloxacin liposomes for increasing bacteria sensitivity， and to evaluate its in vitro property. METHODS Ofloxacin liposomes were prepared by pH gradient method using phospholipid and cholesterol as materials. The effects of pH value and the warming temperature and time on encapsulation efficiency were investigated. The particle size of liposomes was determined and the morphology was investigated by transmission electric microscope (TEM). The in vitro release experiment was carried out using physiological saline as the medium. The bacteriostatic action against Staphylococcus aureus was investigated using disc diffusion test and dilution test. RESULTS The maximum encapsulation efficiency of 82.40% could be achieved when pH value was 7.0， warming temperature was 50 ℃ and warming time was 5 min. The average particle size of the liposomes was 174 nm， and the ofloxacin liposomes showed good morphology under TEM. The liposomes could release ofloxacin in a sustained manner in vitro. The ofloxacin liposomes and solution showed same inhibition zones in disc diffusion test， while their minimal inhibitory concentrations determined by dilution test were 0.39 and 0.78 μg·mL^-1， respectively. CONCLUSION Ofloxacin liposomes can be prepared by pH gradient method with high encapsulation efficiency， and the bacteriostatic effect of ofloxacin against Staphylococcus aureus can be improved by incorporating it into liposomes.