凝胶过滤层析法调节脂质体内外水相pH的探讨

Study on Adjusting pH Gradient Between the Internal and External Water Phase of Liposome Using Gel Filtration Chromatography

通过对脂质体内外水相pH梯度的制备方法的探讨,采用凝胶过滤层析技术将脂质体外水相的pH4.0柠檬酸缓冲液替换成pH 7.2磷酸盐缓冲液,在脂质体内外水相形成pH梯度。在药脂比为1∶5、1∶10、1∶15和1∶20(质量比)时,阿霉素在pH梯度的驱动下从脂质体外水相穿越脂质双分子膜进入内水相,包封率分别达到96.7%、98.7%、96.8%和95.1%,其中药脂比1∶10时包封率达到最高。药脂比1∶10制备的阿霉素脂质体在37℃,12 h内阿霉素泄漏均低于1.0%;48 h内药物泄露率低于5.0%。通过该实验,使学生们能够观测到如何采用凝胶过滤层析技术调节pH梯度,以及pH梯度在阿霉素脂质体主动载药过程中的重要性,为脂质体递释系统的课堂理论教学奠定了良好的实验基础。

pH gradient method is commonly adopted for loading drug into liposome. Depending on pH gradient,drug in the external water phase of liposome could enter into the internal phase. The citric acid buffer（ pH4.0） in external water phase of liposome was changed into phosphate buffer（ pH7. 2） by gel filtration chromatography technology. The pH gradient had found between the internal and external water phase of liposome. Doxorubicin（ DOX） could enter through the lipid membrane into the internal phase driving by pH gradient. When the ratio of drug with lipid were 1∶ 5,1∶ 10,1 ∶ 15,and 1 ∶ 20（ w/w）,the encapsulation rates were 96. 7%,98. 7%,96. 8% and 98. 7%,respectively.Among the above liposome,the encapsulation rate of the liposome with 1∶ 10（ drug： lipid） was the highest. The drug leakage rate of DOX liposome was less than 1. 0% and 5. 0% within 12 h or 48 h at 37 ℃. Through the experiment,the students could realize how to adjust pH gradient using gel filtration chromatography technology,as well as the pH gradient was very important for loading DOX into liposome. It would be built good basis for students studying the liposome delivery system.