一种新型温度响应性聚氨基酸/聚类肽嵌段共聚物的合成与表征

以正己胺为引发剂, 通过γ-炔丙基-L-谷氨酸羧酸酐(PLG-NCA)和N-正辛基甘氨酸羧酸酐(Oct-NNCA)逐步开环聚合和后修饰策略合成了分子量分布较窄的温度响应性两嵌段共聚物寡聚乙二醇单元修饰的聚(γ-炔丙基-L-谷氨酸)-b-聚(N-正辛基甘氨酸)(PPLG-g-EG₃)-b-PNOG]. 通过示差扫描量热法(DSC)研究了不同比例聚合物的结晶行为; 利用圆二色谱法(CD)研究了聚合物的二级结构, 并研究了聚合物在水溶液中的自组装行为, 采用透射电子显微镜(TEM)观察了组装后的形貌. 结果表明, 该温度响应性聚合物在室温下呈现α-螺旋结构, 随着温度升高, α-螺旋的构象减少. 该聚合物可以在水溶液中自发组装成棒状结构.

Synthesis and Characterization of Thermoresponsive Polypeptide/polypeptoid Block Copolymers

Thermoresponsive polymer refers to a type of polymer that can respond to external temperature and the molecular structure exhibit reversible or irreversible changes， that show great potential for both fundamental research and applications. In this work， both polypeptide and polypeptoid are involved to construct a new type of thermoresponsive block copolymers， which combine the structural advantages for tunable properties. We used n-hexylamine as an initiator and synthesized a series of thermoresponsitive diblock copolymer oligo（ethylene glycol） modified poly（γ-propargyl-L-glutamate）-block-poly（N-octylglycine）［（PPLG-g-EG₃）-b-PNOG］ with narrow molecular mass distribution by ring-opening polymerization and post-modification strategy. The crystallization behavior of the polymers was studied by differential scanning calorimetry. Circular dichroism（CD） spectrum was used to investigate the secondary structure of the polymer， and its self-assembly behavior in aqueous solution was further investigated. The results show that the thermoresponsitive polymers adopt α-helix at room temperature. As the temperature increases， the fraction of α-helix decreases. Additionally， the obtained polymers exhibit cylindrical nanostructure in aqueous solution.