聚乙二醇-聚乙烯亚胺共聚物的制备及其表征

用亲水的聚乙二醇对聚乙烯亚胺进行改性，制备适用于基因转染的非病毒类载体。以异佛尔酮二异氰酸酯活化聚乙二醇，再与聚乙烯亚胺反应，两步法合成了聚乙二醇-聚乙烯亚胺（PEG—PEI）嵌段共聚物，分别用IR、^1H NMR、GPC、DSC列共聚物进行了表征。在IR谱图上可见mPEG—NCO中异氰酸基、及PEG—PEI中脲基的特征峰；根据^1H NMR谱图计算表明，此聚合反应为可控反应，通过调节PEG与PEI的投料比例可控制共聚物组成及相对分子质量；GPC曲线上共聚物为一单峰，与PEG和PEI均聚物峰位置不同，表明产物是PEGPE共聚物，DSC分析也表明共聚物Tm。较均聚物均有不同程度的下降，这是PEG和PEI两种嵌段相互缠结的结果。因此证明成功合成了PEG—PEI共聚物。

Synthesis and Characterization of Poly ( ethylene Glycol) - Polyethlenimine Copolymer

PEI was modified with PEG in order to improve its physical properties for nonviral gene delivery, mPEG was modified with IPDI, which was reacted with PEI to synthesize the block copolymer of PEG-PEI. The copolymer was characterized by IR, ^1H NMR, GPC, DSC analysis. IR spectrum showed the absorption of the isocyanate of mPEG-NCO and absorption of the urea bond of PEG-PEI. The results of^ 1 H NMR analysis indicated the polymerization was a controlled reation, in which the composition and molecular weight of the copolymer could he controlled throuth adjusting ratio rates. The GPC of the copolymer exhibited only one peak different from that of PEG and PEI homopolymers, illustrating the product only contained PEG-PEI copolymer. DSC measurements of copolymer showed a shift of Tm to lower values in comparison to the Tm of PEG homopolymer, implying the entanglement of the two blocked chains. The results indicated the PEG-PEI block copolyers were synthesized successfully.