Polyethylenimine-graft-poly(ethylene glycol) copolymers:: Influence of copolymer block structure on DNA complexation and biological activities as gene delivery system
Polyethylenimine-graft-poly(ethylene glycol) copolymers:: Influence of copolymer block structure on DNA complexation and biological activities as gene delivery system
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DOI：
10.1021/bc025529v
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发表时间：
2002-07-01
影响因子：
4.7
通讯作者：
Kissel, T
中科院分区：
文献类型：
--
作者：
Petersen, H;Fechner, PM;Kissel, T
研究了两个系列的聚乙烯亚胺-接枝-聚乙二醇（PEI-g-PEG）嵌段共聚物的结构对DNA复合的影响，并比较了这两个系列的复合物的理化性质、血液相容性、细胞毒性和转染活性。在第一系列中，PEI（25 kDa）被PEG（5 kDa）接枝至不同的取代度，并且在第二系列中，PEG的分子量（MW）是变化的（550 Da至20 kDa）。使用原子力显微镜，我们发现，共聚物嵌段结构强烈影响DNA复合物的大小和形态：PEG 5 kDa显着减少的球形复合物的直径从142 +/- 59至61 +/- 28 nm。随着PEG接枝程度的增加，DNA的络合受到阻碍，络合物失去其球形。与PEG 20 kDa的共聚物产生小，紧凑的复合物与DNA（51 - 23 nm），而与PEG 550 Da的共聚物导致在大和弥漫的结构（130 +/- 60 nm）。如果分子量为5 kDa，复合物的zeta电位随着PEG接枝程度的增加而降低。PEG 550 Da不能充分屏蔽PEI的正电荷，导致溶血和红细胞聚集。细胞毒性（乳酸脱氢酶测定）是独立的PEG分子量，但PEG取代的程度的影响：所有共聚物与超过6个PEG块形成DNA复合物的低毒性。最后，研究了复合物的转染效率。大颗粒、低毒性和高正表面电荷的组合，如在具有许多PEG 550 Da嵌段的共聚物的情况下，被证明对于体外基因转移是最有效的。总之，PEG的PEG化程度和MW被发现强烈影响PEI的DNA缩合，因此也影响PEI-g-PEG/DNA复合物的生物活性。这些结果为合理设计嵌段共聚物基因传递系统提供了依据。
For two series of polyethylenimine-graft-poly(ethylene glycol) (PEI-g-PEG) block copolymers, the influence of copolymer structure on DNA complexation was investigated and physicochemical properties of these complexes were compared with the results of blood compatibility, cytotoxicity, and transfection activity assays. In the first series, PEI (25 kDa) was grafted to different degrees of substitution with PEG (5 kDa) and in the second series the molecular weight (MW) of PEG was varied (550 Da to 20 kDa). Using atomic force microscopy, we found that the copolymer block structure strongly influenced the DNA complex size and morphology: PEG 5 kDa significantly reduced the diameter of the spherical complexes from 142 +/- 59 to 61 +/- 28 nm. With increasing degree of PEG grafting, complexation of DNA was impeded and complexes lost their spherical shape. Copolymers with PEG 20 kDa yielded small, compact complexes with DNA (51 23 nm) whereas copolymers with PEG 550 Da resulted in large and diffuse structures (130 +/- 60 nm). The zeta-potential of complexes was reduced with increasing degree of PEG grafting if MW : 5 kDa. PEG 550 Da did not shield positive charges of PEI sufficiently leading to hemolysis and erythrocyte aggregation. Cytotoxicity (lactate dehydrogenase assay) was independent of MW of PEG but affected by the degree of PEG substitution: all copolymers with more than six PEG blocks formed DNA complexes of low toxicity. Finally, transfection efficiency of the complexes was studied. The combination of large particles, low toxicity, and high positive surface charge as in the case of copolymers with many PEG 550 Da blocks proved to be most efficient for in vitro gene transfer. To conclude, the degree of PEGylation and the MW of PEG were found to strongly influence DNA condensation of PEI and therefore also affect the biological activity of the PEI-g-PEG/DNA complexes. These results provide a basis for the rational design of block copolymer gene delivery systems.