摘要胍基基团具有良好的细胞膜穿透能力，将其连接到阳离子聚合物上能够帮助聚合物进入细胞，并且能分散聚合物上伯胺的正电荷，降低其毒性，从而提高聚合物的基因转染效率。本文设计合成了一种型胍基化试剂，用它来修饰聚合物，以期提高它们的转染效率。60118

聚乙烯亚胺(PEI)是目前最有效的阳离子非病毒基因载体之一，PEI的转染效率随着其分子量的增加而增加，但是高分子量同样会导致高毒性。本文采用胍基化试剂修饰不同分子量的PEI，探索胍基修饰度以及胍基基团与PEI的连接臂长对转染效率的影响。其次合成了一种多羟基的交联剂，用其交联小胺类单体及低分子量的PEI，并用胍基化试剂对制备出来的聚合物进行修饰，以探讨引入羟基和胍基对聚合物的水溶性，毒性及转染性能的影响。此外，聚β氨酯也是一类非常有效的阳离子非病毒载体，本文通过1,4-丁二醇双丙烯酸酯与5-氨基戊醇交联制得聚β氨酯，用氨基封端，并用所合成的胍基化试剂修饰，探讨胍基修饰前后聚β氨酯的转染性能的变化。

    对这些聚合物进行水溶性评价，然后以B16F10细胞为受体，增强绿色荧光蛋白质粒(EGFP)为报告基因进行细胞转染性能实验，筛选出几种转染效果较好的聚合物，其中经胍基化修饰后的2700Da PEI(C4)对B16F10细胞的转染效率达到了56%，与未修饰前相比，提高了近8倍。细胞毒性实验结果表明，经胍基修饰后的聚合物毒性明显降低。

毕业论文关键词：胍基化，基因转染，非病毒载体，聚乙烯亚胺，聚β氨酯

毕业设计说明书（论文）外文摘要

Abstract Guanidine groups have great cellular penetrating ability and it will facilitate cellular uptake of the cationic polymers if grafting guanidine groups to them. The guanidine groups could also lead to the delocalization of charge present on primary amines of the polymer thereby leading to enhancement in delivery efficiency along with reduction in cytotoxicity. In the present study，a novel guanidinylation reagent was designed and synthesized and used to modify polymers in order to increase their transfection efficiency.

Polyethylenimine(PEI) is one of the most efficient polycationic non-viral gene delivery vectors. Its efficiency and cytotoxicity depends on its molecular weight, high molecular weight leads to high efficiency, but also high cytotoxicity. In this paper, PEI of different molecular and cross-linked PEI derivatives were modified with guanidinylation reagent. The influence of guanidination degree and the length between PEI and guanidine groups on the transfection efficiency was discussed.

The polymers with good water-solubility were assessed when B16F10 cells were used as receptor cells and enhanced green fluorescent protein (EGFP) was used as gene reporter. Among these polymers, we got some polymers with high transfection efficiency. It was found that in B16F10 cells, guanidinated PEI(2700Da) showed 56% of green color expressing cells, almost 8 times higher than that of native PEI itself. The cytotoxicity of guanidinated polymer–DNA complexes was also reduced considerably in comparison to non-guanidinated polymer, as determined by MTT colorimetric assay. 

Keywords: Guanidination, Gene transfection, non-viral, Polyethylenimine(PEI), Poly (β-amino ester)

1  引言 2

1.1 非病毒基因传递的主要障碍 3

1.1.1  细胞吸收的体外障碍 3

1.1.2  基因转染载体 5

1.2  研究内容 6

2  聚合物的合成及胍基化修饰