聚肽三嵌段共聚物棒状胶束的超分子环化行为研究  

Supramolecular Cyclization Behavior of Rodlike Micelles Assembled from Polypeptide Triblock Copolymers

作　　者：任许乐 蔡春华[1] 林嘉平[1] Xu-le Ren;Chun-hua Cai;Jia-ping Lin(School of Materials Science and Engineering,East China University of Science and Technology,Shanghai 200237)

机构地区：[1]华东理工大学材料科学与工程学院,上海200237

出　　处：《高分子学报》2024年第12期1668-1679,共12页Acta Polymerica Sinica

基　　金：国家自然科学基金(基金号52394271,52073095)资助

摘　　要：以双端氨基聚乙二醇(NH2-PEG-NH2)作为大分子引发剂,以γ-苄基-L-谷氨酸酯五元环酸酐(BLGNCA)为单体,通过开环聚合法合成了聚(γ-苄基-L-谷氨酸酯)-嵌段-聚乙二醇-嵌段-聚(γ-苄基-L-谷氨酸酯)(PBLG-b-PEG-b-PBLG)三嵌段共聚物.运用核磁共振氢谱(1H-NMR)和凝胶渗透色谱(GPC)表征了聚合物的结构、分子量及其分布.采用四氢呋喃/N,N-二甲基甲酰胺(THF/DMF)有机共溶剂溶解、滴加选择性溶剂(水)并透析的方法,制备了聚肽纳米棒水溶液;然后向纳米棒水溶液中加入THF诱导纳米棒发生弯曲成环.通过扫描电子显微镜(SEM)、透射电子显微镜(TEM)、动态激光光散射(DLS)表征了组装体的形貌与结构,研究了聚合物分子量、成环时间、温度、THF加入量对组装体形貌的影响.研究发现,PBLG链段聚合度显著影响棒状胶束的直径及长度,在THF的诱导下,具有较大长径比的棒状胶束可以发生超分子环化,而较短的纳米棒仅能发生弯曲,更短的纳米棒则保持形貌不变.温度升高有利于THF诱导的超分子环化现象的发生.采用圆二色光谱(CD)表征了PBLG主链结构及侧链的排列信息,发现THF的加入不影响主链的α-螺旋构象,但是侧链发生收缩,侧链苯环排列变得更为紧密.这种侧链收缩产生内应力导致纳米棒塌缩,从而驱动纳米棒弯曲成环.该研究模仿了生物体系中形成复杂结构的多级自组装策略,通过棒状胶束的逐步自组装制备了聚肽纳米环,丰富了纳米环的制备方法,拓展了超分子环化反应的研究范围,将为聚合物纳米环的可控制备及其功能应用提供指导.Poly(γ-benzyl-L-glutamate)-block-poly(ethylene glycol)-block-poly(γ-benzyl-L-glutamate)(PBLG-b-PEG-b-PBLG)triblock copolymers were synthesized using amine-PEG-amine(NH2-PEG-NH2)as macroinitiator via ring-opening polymerization ofγ-benzyl-L-glutamate N-carboxyanhydride(BLG-NCA).The molecular weight and molecular weight distribution of the polymers were characterized by proton nuclear magnetic resonance spectroscopy(1H-NMR)and gel permeation chromatography(GPC).Rodlike micelles were assembled from the PBLG-b-PEG-b-PBLG triblock copolymers using a mixture of tetrahydrofuran and N,N-dimethylformamide(THF-DMF)as initial solvent.The PBLG segments are perpendicular to the long axis in the rodlike micelles.Under THF addition,the rodlike micelles bend to form curved rodlike micelles and then toroid micelles.The morphology and structure of the assemblies were characterized using scanning electron microscopy(SEM),transmission electron microscopy(TEM),and dynamic light scattering(DLS).The degree of bending of the nanorods can be adjusted by variation of the polymer molecular weight,toroid forming time,temperature,and THF adding content.The degree of polymerization of PBLG segments affects the diameter of rodlike micelles.The aspect ratio of the rodlike micelles determines whether supramolecular cyclization occurs.The addition of THF and the increase of temperature promote the occurrence of supramolecular cyclization behavior.The effect of temperature on supramolecular cyclization behavior exhibits a certain degree of reversibility.CD spectra were employed to characterize arrangement of the phenyl rings in the PBLG segments,revealing that the contraction of the phenyl rings induced by THF is the driving force for the bending of the nanorods.The research mimicking the hierarchical self-assembly strategy in preparing complex structures by biosystems,reported a step-wise self-assembly of polypeptides into nanotoroids.The study enriches the preparation method for polymer nanotoroids,and will guide the controlled preparation of

关 键 词：聚肽共聚物 多级自组装 棒状胶束 超分子环化 苯环排列 

分 类 号：O641.3[理学—物理化学] O631.5[理学—化学]