Nanostructure of Polyplexes Formed between Cationic Diblock Copolymer and Antisense Oligodeoxynucleotide and Its Influence on Cell Transfection Efficiency
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- 作者：XiuBo Zhao ; Fang Pan ; ZhuoQi Zhang ; Colin Grant ; YingHua Ma ; Steven P. Armes ; YiQing Tang ; Andrew L. Lewis ; Thomas Waigh ; Jian R. Lu
- 刊名：Biomacromolecules
- 出版年：2007
- 出版时间：November 2007
- 年：2007
- 卷：8
- 期：11
- 页码：3493 - 3502
- 全文大小：532K
- 年卷期：v.8,no.11(November 2007)
- ISSN：1526-4602
文摘
Although various cationic polymers have been used to condense anionically charged DNA to improve theirtransfection efficiency, there is still a lack of fundamental understanding about how to control the nanostructureand charge of the polyplexes formed and how to relate such information to cell transfection efficiency. In thiswork, we have synthesized a weak cationic and phosphorylcholine-containing diblock copolymer and used it asa model vector to deliver an antisense oligodeoxynucleotide (ODN) into HeLa cells. Small angle neutron scattering(SANS) was used to determine the copolymer/ODN polyplex structure. The SANS data revealed the formationof polyplex nanocylinders at high copolymer (N)/ODN (P) charge ratios, where N symbolizes the amine groupson the copolymer and P symbolizes the phosphate groups. However, the cylindrical lengths remained constant,indicating that the ODN binding over this region did not alter the cylindrical shape of the copolymer in solution.As the N/P ratio decreased and became close to unity the polyplex diameters remained constant, but their lengthsincreased substantially, suggesting the end-to-end bridging by ODN binding between copolymer cylinders. Asthe N/P ratios went below unity (with ODN in excess), the polyplex diameters increased substantially, indicatingdifferent ODN bridging to bundle the small polyplexes together. Transfection studies from HeLa cells indicateda steady increase in transfection efficiency with increasing cationic charge and decreasing polyplex size. Cellgrowth inhibition assay showed significant growth inhibition by the polyplexes coupled with weak cytotoxicity,indicating effective ODN delivery. While this study has confirmed the overall charge effect, it has also revealedprogressive structural changes of the polyplexes against varying charge ratio, thereby providing useful insightinto the mechanistic process behind the ODN delivery.