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合成了氧化还原调控的甲氧基聚乙二醇-二硫键-聚乙烯亚胺[methoxy poly(ethylene glycol)-SS-polyethylenimine,mPEG-SS-PEI]。采用薄层色谱验证了该聚合物中二硫键的存在。琼脂糖凝胶电泳结果显示,mPEG-SS-PEI-pEGFP复合物在含10%胎牛血清的DMEM细胞培养液中稳定。透射电镜观察表明,不含二硫键的mPEG-PEI及mPEG-SS-PEI与pEGFP复合物的粒径均约为200 nm。体外转染试验中,荧光显微镜定性及流式细胞定量结果均表明,与mPEG-PEI-pEGFP相比,mPEG-SS-PEI-pEGFP能显著提高对U87细胞的转染效率。原因是mPEG-SS-PEI-pEGFP复合物进入细胞后能在较高浓度谷胱甘肽的还原下脱去PEG,从而恢复PEI的质子泵效应。并且,聚合物中加入二硫键未显著增加PEG化PEI的体外细胞毒性。
The redox-mediated methoxy poly (ethylene glycol) -SS-polyethylenimine, mPEG-SS-PEI] was synthesized. The presence of disulfide bonds in the polymer was verified by thin layer chromatography. The results of agarose gel electrophoresis showed that the mPEG-SS-PEI-pEGFP complex was stable in DMEM cell culture medium containing 10% fetal bovine serum. Transmission electron microscopy showed that the size of mPEG-PEI and mPEG-SS-PEI without disulfide bonds and pEGFP complexes were about 200 nm. In vitro transfection experiments, fluorescence microscopy qualitative and quantitative flow cytometry results showed that, compared with the mPEG-PEI-pEGFP, mPEG-SS-PEI-pEGFP can significantly improve the transfection efficiency of U87 cells. The reason for this is that the mPEG-SS-PEI-pEGFP complex rescued the proton-pump effect of PEI after it entered the cell and removed PEG at a higher concentration of glutathione. Also, addition of disulfide bonds to the polymer did not significantly increase the cytotoxicity of PEGylated PEI in vitro.