胆固醇-聚乙烯亚胺共聚物的制备及其表征

Synthesis and characterization of polyethyleneimine-cholesterol copolymer

目的用胆固醇(Chol)对聚乙烯亚胺(PEI)进行改性,制备适用于基因转染的非病毒类载体。方法用胆固醇甲酰氯(Chol-Cl)连接聚乙烯亚胺的氨基形成PEI-Chol脂质共聚物,分别用IR、1H-NMR、凝胶色谱法、DSC对聚合物进行表征。结果在IR图谱上可见1 800 cm-1峰为Chol-Cl的羰基特征峰,形成PEI-Chol后,羰基特征峰迁移至1 700 cm-1,表明聚乙烯亚胺与胆固醇成功连接;根据1H-NMR谱图计算PEI的胺基接枝率、组成及相对分子质量,达到试验预期效果,表明反应可控;凝胶色谱法测定发现聚合物为单峰,表明连接成功,且聚合物相对分子质量的测定值与1H-NMR估算值比较接近;DSC图谱显示PEI连接胆固醇,Chol-Cl的吸收峰消失,熔融峰(Tm)升高变钝,表明PEI-Chol刚性增强。结论成功合成了PEI-Chol脂质共聚物。

Objective Polyethyleneimine（PEI） was modified with cholesterol（Chol） in order to improve its physical properties for nonviral gene delivery.Method PEI-Chol lipopolymer was synthesized by linking cholesteryl chloroformate（Chol-cl） to the amino groups of branched poly（ethylenimine）（PEI）.The copolymer was characterized by IR,1H-NMR,gel permeation chromatography（GPC） and DSC analysis.Result IR spectrum showed the special carbonyl peak（1 800 cm^-1） of Chol-Cl changed into the carbonyl peak（1 700 cm^-1） of PEI-Chol which meant the bond connection of PEI and Chol.The results of 1H-NMR analysis indicated the polymerization was a controlled reaction in which the composition and molecular weight of the copolymer could be controlled through adjusting ratio rates.The GPC of the polymer as a single peak indicated that the connection between PEI and Chol-Cl was successful,and the polymer molecular weight of PEI-Chol were relatively close to the the estimated results with the 1H-NMR.DSC plots showed the absorption peak of Chol-Cl disappeared and the the melting peaks（Tm） increased,which meant the rigidity of PEI enhanced after connection of cholesterol.Conclusions The results indicated the PEI-Chol block copolyers were synthesized successfully.