甘草次酸修饰的长循环阳离子脂质体DNA复合物的制备

Preparation of Long-Circulating Lipoplexes Modified with Glycyrrhetinic Acid

目的合成甘草次酸-聚乙二醇-胆固醇偶合物,并运用该材料制备具有肝细胞靶向作用的阳离子脂质体DNA复合物。方法丁二酰化甘草次酸和丁二酰化胆固醇与聚乙二醇通过酯键偶联,合成甘草次酸-聚乙二醇-胆固醇偶合物,并通过芘荧光探针法测定其临界胶束浓度;采用前、后聚乙二醇化法制备阳离子脂质体DNA复合物,以粒径为指标优选制备工艺。结果甘草次酸-聚乙二醇-胆固醇偶合物是一种具有低临界胶束浓度的载体材料,临界胶束质量浓度为5.9×10-4～3×10-3g.L-1;前、后聚乙二醇化法制备的阳离子脂质体DNA复合物粒径分别为(297.9±8.16),(178.7±5.4)nm,Zeta电位分别为(28.34±1.23),(26.72±0.52)mV。结论具有低临界胶束浓度的甘草次酸-聚乙二醇-胆固醇偶合物合成工艺简单、成本低廉,宜用于聚乙二醇化法制备具有潜在肝细胞靶向的阳离子脂质体DNA复合物。

OBJECTIVE To synthesize glycyrrhetinic acid-poly （ethylene glycol）-cholesterol （GA-PEG-Chol） and to prepare cationic liposome/DNA （lipoplexes） targeting for hepatoeytes. METHODS GA-PEG-Chol was synthesized by conjugating 18-β-gly- eyrrhetinic acid succinie anhydride ester （mGA-suc） with PEG2000 and cholesterol succinic anhydride ester （Chol-suc）. The critical micelle concentration （CMC） of GA-PEG-Chol was determined by pyrene fluorescence probe spectrometry. The lipoplexes were pro- duced by pre-PEGylation and post-PEGylation method, respectively. The optimal preparation method was determined by comparison of mean particle diameters and size distributions. RESULTS The CMC of GA-PEG-Chol was 5.9 × 10 ^4 - × 10 ^-3 g . L^- 1 which was much lower than those of many low molecular weight surfactants. The average sizes of lipoplexes prepared by pre-PEGylation and post- PEGylation method were （297.9±8. 16） and （178.7 ±5.4） nm, respectively （n =3）. However, the Zeta potentials of lipoplexes prepared by the two method did not show significant difference, which were （ 28.34 ± 1.23 ） and （ 26. 72 ± 0. 52 ） mV, respectively （n = 3 ）. CONCLUSION The synthesis process of GA-PEG-Chol is simple and cost-effective. Post-PEGylation method is the better method to prepare long-circulating lipoplexes modified with glycyrrhetinic acid.