Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Institute of Functional Nano and Soft Materials (FUNSOM), Soochow University , Suzhou 215123, P. R. China.
Department of Chemistry and Macromolecular Studies Group, Louisiana State University , Baton Rouge, Louisiana 70803, United States.
ACS Appl Mater Interfaces. 2017 Jul 19;9(28):23476-23486. doi: 10.1021/acsami.7b06031. Epub 2017 Jul 6.
The rational design of gene vectors relies on the understanding of their structure-property relationship. Polypeptoids, which are structural isomers of natural polypeptides, hold great potential as gene delivery vectors due to their facile preparation, structural tunability, and most importantly, their desirable proteolytic stability. We herein designed a library of polypeptoids with different cationic side-chain terminal groups, degree of polymerizations (DPs), side-chain lengths, and incorporated aliphatic side chains, to unravel the structure-property relationships so that gene delivery efficiency can be maximized and cytotoxicity can be minimized. In HeLa cells, a polypeptoid bearing a primary amine side-chain terminal group exhibited remarkably higher transfection efficiency than that of its analogues containing secondary, tertiary, or quaternary amine groups. Elongation of the polypeptoid backbone length (from 28 to 251 mer) led to enhanced DNA condensation as well as cellular uptake levels, however it also caused higher cytotoxicity. Upon a proper balance between DNA uptake and cytotoxicity, the polypeptoid with a DP of 46 afforded the highest transfection efficiency. Elongating the aliphatic spacer between the backbone and side amine groups enhanced the hydrophobicity of the side chains, which resulted in notably increased membrane activities and transfection efficiency. Further incorporation of hydrophobic decyl side chains led to an improvement in transfection efficiency of ∼6 fold. The top-performing material identified, P11, mediated successful gene transfection under serum-containing conditions, outperforming the commercial transfection reagent poly(ethylenimine) by nearly 4 orders of magnitude. Reflecting its excellent serum-resistant properties, P11 further enabled effective transfection in vivo following intratumoral injection to melanoma-bearing mice. This study will help the rational design of polypeptoid-based gene delivery materials, and the best-performing material identified may provide a potential supplement to existing gene vectors.
基因载体的合理设计依赖于对其结构-性能关系的理解。多肽类似物是天然多肽的结构异构体，由于其易于制备、结构可调性以及最重要的是理想的蛋白水解稳定性，它们具有作为基因传递载体的巨大潜力。我们在此设计了一系列具有不同阳离子侧链末端基团、聚合度（DP）、侧链长度和引入脂肪侧链的多肽类似物文库，以揭示结构-性能关系，从而最大限度地提高基因传递效率并最小化细胞毒性。在 HeLa 细胞中，带有伯胺侧链末端基团的多肽类似物表现出比含有仲胺、叔胺或季铵基团的类似物更高的转染效率。多肽类似物主链长度的延长（从 28 到 251 个单体）导致 DNA 凝聚和细胞摄取水平的提高，但也导致更高的细胞毒性。在 DNA 摄取和细胞毒性之间取得适当平衡的情况下，DP 为 46 的多肽类似物提供了最高的转染效率。延长主链和侧胺基团之间的脂肪间隔增强了侧链的疏水性，从而导致膜活性和转染效率显著提高。进一步引入疏水性癸基侧链可将转染效率提高约 6 倍。鉴定出的表现最佳的材料 P11，在含血清条件下成功介导基因转染，比商业转染试剂聚（亚乙基亚胺）高近 4 个数量级。反映其出色的耐血清特性，P11 进一步能够在荷瘤小鼠经肿瘤内注射后在体内进行有效的转染。这项研究将有助于基于多肽类似物的基因传递材料的合理设计，而鉴定出的表现最佳的材料可能为现有基因载体提供潜在的补充。
