Graduate School of Organic Materials Science, Yamagata University, 4-3-16, Jonan, Yonezawa 992-8510, Japan.
Department of Chemical Biology and Applied Chemistry, College of Engineering, Nihon University, 1 Nakagawara, Tokusada, Tamuramachi, Koriyama, Fukushima 963-8642, Japan.
Langmuir. 2021 Mar 16;37(10):3001-3014. doi: 10.1021/acs.langmuir.0c02197. Epub 2021 Mar 2.
Two series of poly(vinyl amine) (PVAm)-based block copolymers with zwitterionic and thermoresponsive segments were synthesized by the reversible addition-fragmentation chain transfer polymerization. A mixture of the two copolymers, poly(-acryloyl-l-lysine) (PALysOH) and poly(-isopropylacrylamide) (PNIPAM), which have the same cationic PVAm chain but different shell-forming segments, were used to prepare mixed polyplex micelles with DNA. Both PVAm--PALysOH and PVAm--PNIPAM showed low cytotoxicity, with characteristic assembled structures and stimuli-responsive properties. The cationic PVAm segment in both block copolymers showed site-specific interactions with DNA, which were evaluated by dynamic light scattering, zeta potential, circular dichroism, agarose gel electrophoresis, atomic force microscopy, and transmission electron microscopy measurements. The PVAm--PNIPAM/DNA polyplexes showed the characteristic temperature-induced formation of assembled structures in which the polyplex size, surface charge, chiroptical property of DNA, and polymer-DNA binding were governed by the nitrogen/phosphate (N/P) ratio. The DNA binding strength and colloidal stability of the PVAm--PALysOH/DNA polyplexes could be tuned by introducing an appropriate amount of zwitterionic PALysOH functionality, while maintaining the polyplex size, surface charge, and chiroptical property, regardless of the N/P ratio. The mixed polyplex micelles showed temperature-induced stability originating from the hydrophobic (dehydrated) PNIPAM chains upon heating, and remarkable stability under salty conditions owing to the presence of the zwitterionic PALysOH chain on the polyplex surface.
通过可逆加成-断裂链转移聚合合成了两系列带有两性离子和温敏性段的聚（乙烯基胺）（PVAm）嵌段共聚物。两种共聚物，聚（丙烯酰-L-赖氨酸）（PALysOH）和聚（异丙基丙烯酰胺）（PNIPAM）的混合物，具有相同的阳离子 PVAm 链但具有不同的壳形成段，用于制备具有 DNA 的混合聚电解质胶束。PVAm-PALysOH 和 PVAm-PNIPAM 均表现出低细胞毒性，具有特征组装结构和刺激响应特性。两种嵌段共聚物中的阳离子 PVAm 段与 DNA 具有特定的相互作用，这通过动态光散射、Zeta 电位、圆二色性、琼脂糖凝胶电泳、原子力显微镜和透射电子显微镜测量来评估。PVAm-PNIPAM/DNA 聚电解质胶束表现出特征的温度诱导组装结构形成，其中聚电解质胶束的大小、表面电荷、DNA 的手性性质以及聚合物-DNA 结合受氮/磷（N/P）比的控制。PVAm-PALysOH/DNA 聚电解质胶束的 DNA 结合强度和胶体稳定性可以通过引入适量的两性离子 PALysOH 官能团来调节，同时保持聚电解质胶束的大小、表面电荷和手性性质，而与 N/P 比无关。混合聚电解质胶束表现出源于加热时疏水性（脱水）PNIPAM 链的温度诱导稳定性，并且由于聚电解质胶束表面存在两性离子 PALysOH 链，因此在含盐条件下具有显著的稳定性。
