A series of cationic polypeptide imidazolium conjugates were prepared by ring-opening polymerization (ROP) of γ-4-(3-chloropropoxycarbonyl)benzyl-_L- glutamic acid-based N-carboxyanhydride (CPBLG-NCA) initiated by various mono- or diamine initiators and subsequent side-chain modification with high grafting efficiency. Rapid and controlled ROP was achieved by polymerizing CPBLG-NCA in a dichloromethane/NaHCO₃/H₂O solvent mixture with the amine initiators. The resulting polypeptides bearing imidazolium iodide pendants showed reversible upper critical solution temperature (UCST)-type thermoresponsive properties in both ethanol and DI water while the polypeptides with tetrafluoroborate counter-anions showed a UCST in phosphate buffer saline (PBS). The cloud point temperature (T_cp) in ethanol and aqueous solutions can be tuned by both molecular weight and the end- or linkage-groups in the main chain. The cationic polypeptides showed good antibacterial activity against Staphylococcus aureus and low hemolysis. Our results provide a facile and rapid ROP strategy to develop new families of stimuli-responsive polypeptides with tunable properties as well as antibacterial polypeptides with optimized selectivity.

中文翻译：

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单胺或二胺引发的基于咪唑鎓的阳离子多肽的合成及性能。

通过各种单胺或二胺引发的γ-4-（3-氯丙氧基羰基）苄基_-L-谷氨酸基N-羧基酐（CPBLG-NCA）的开环聚合（ROP），制备了一系列阳离子多肽咪唑鎓共轭物。引发剂和随后的具有高接枝效率的侧链修饰。通过在二氯甲烷/ NaHCO ₃ / H _2中聚合CPBLG-NCA可实现快速而受控的ROPO与胺引发剂的溶剂混合物。所得带有碘化咪唑鎓侧基的多肽在乙醇和去离子水中均显示出可逆的上临界溶液温度（UCST）型热响应特性，而带有四氟硼酸抗衡阴离子的多肽在磷酸盐缓冲液（PBS）中显示出UCST。乙醇和水溶液中的浊点温度（T _cp）可以通过分子量以及主链中的端基或连接基团进行调节。阳离子多肽对金黄色葡萄球菌具有良好的抗菌活性和低溶血。我们的结果提供了一种简便而快速的ROP策略，以开发具有可调特性的新的刺激响应多肽家族以及具有优化选择性的抗菌多肽。