Key Laboratory of Biomedical Polymers of the Ministry of Education & Department of Chemistry, Wuhan University, Wuhan 430072, PR China.
Chemistry. 2012 Feb 20;18(8):2297-304. doi: 10.1002/chem.201102704. Epub 2012 Jan 16.
Two thermo- and pH-sensitive polypeptide-based copolymers, poly(N-isopropylacrylamide-co-N-hydroxymethylacrylamide)-b-poly(L-lysine) (P(NIPAAm-co-HMAAm)-b-PLL, P1) and poly(N-isopropylacrylamide-co-N-hydroxymethylacrylamide)-b-poly(glutamic acid) (P(NIPAAm-co-HMAAm)-b-PGA, P2), have been designed and synthesized by the ring-opening anionic polymerization of N-carboxyanhydrides (NCA) with amino-terminated P(NIPAAm-co-HMAAm). It was found that the block copolymers exhibit good biocompatibility and low toxicity. As a result of electrostatic interactions between the positively charged PLL and negatively charged PGA, P1 and P2 formed polyion complex (PIC) micelles consisting of polyelectrolyte complex cores and P(NIPAAm-co-HMAAm) shells in aqueous solution. The thermo- and pH-sensitivity of the PIC micelles were studied by UV/Vis spectrophotometry, dynamic light scattering (DLS), and transmission electron microscopy (TEM). Moreover, fluorescent PIC micelles were achieved by introducing two fluorescent molecules with different colors. Photographs and confocal laser scanning microscopy (CLSM) showed that the fluorescence-labeled PIC micelles exhibit thermo- and pH-dependent fluorescence, which may find wide applications in bioimaging in complicated microenvironments.
两种热和 pH 敏感的多肽基嵌段共聚物，聚（N-异丙基丙烯酰胺-co-N-羟甲基丙烯酰胺）-b-聚（L-赖氨酸）（P（NIPAAm-co-HMAAm）-b-PLL，P1）和聚（N-异丙基丙烯酰胺-co-N-羟甲基丙烯酰胺）-b-聚（谷氨酸）（P（NIPAAm-co-HMAAm）-b-PGA，P2），已通过氨基酸封端的 N-羧基酸酐（NCA）的开环阴离子聚合设计和合成。结果发现嵌段共聚物具有良好的生物相容性和低毒性。由于带正电荷的 PLL 和带负电荷的 PGA 之间的静电相互作用，P1 和 P2 在水溶液中形成由聚电解质复合物核和 P（NIPAAm-co-HMAAm）壳组成的聚离子复合物（PIC）胶束。通过紫外/可见分光光度法、动态光散射（DLS）和透射电子显微镜（TEM）研究了 PIC 胶束的热和 pH 敏感性。此外，通过引入两种具有不同颜色的荧光分子实现了荧光 PIC 胶束。照片和共焦激光扫描显微镜（CLSM）显示，荧光标记的 PIC 胶束表现出热和 pH 依赖性荧光，这可能在复杂微环境中的生物成像中有广泛的应用。
