双响应强荧光型超支化聚硅氧烷的构筑及药物控释可视化

Non-aromatics fluorescent polymers with aggregation-induced-emission effect have surged in recent years owing to their good biocompatibility, low cytotoxicity to cells and easy preparation, as well as their tremendously latent applications in drug delivery, cellular imaging, genetic analysis, biosensors and clinical diagnosis. However, several drawbacks are still remained, such as low fluorescence intensity and functionality, inadequate stimuli-responsive properties. Especially, the in-depth and unified understanding on structure-activity relationship between their microstructures and photoluminescence properties has not been formed, and this severely restricts the development of new light-emitting materials..This project focuses on the improvement of the fluorescence intensity and stimulus-responsive properties of the hyperbranched polymers by adjusting of their spatial conjugation and self-assembly behaviors via the combined action of multiple hydrogen bonds and non-metal coordination bonds. First of all, a series of novel hyperbranched polysiloxanes with carbonyl groups are synthesized by the nucleophilic replacement polycondensation to increase the spatial conjugation effect, the relationship between their chemical structures (molecule weight, functional groups and degree of branching) and photoluminescence properties are systematically studied. Then, the rigid units in β-cyclodextrin and soft segments in polyether are grafted into the above HBPSi to regulate their self-assembly behaviors, which further increases the spatial conjugation and their fluorescence intensity, hoping to get the supramolecular hyperbranched polysiloxanes with the temperature and pH dual-responsive properties as well as the controllable drug release properties. .The proposed project can not only provide theoretical direction for designing non-aromatics aggregation-induced-emission hyperbranched polymers with simple production technique, high fluorescence intensity, good intelligence and multi functionalities, but will also lay the foundation of “visible” controlled release of drugs.

非芳香族聚集诱导发光（AIE）聚合物具有生物相容性好、细胞毒性小、合成方法简单等优点，但存在荧光强度不高、刺激响应性单一、功能性不足等缺陷，且缺乏系统的发光理论。本项目提出通过多重氢键和非金属配位键的共同作用来调控超支化聚合物的自组装行为及空间共轭效应以提高其荧光强度的同时赋予其双重刺激响应性的新思想。首先，以亲核取代缩聚反应设计合成一类含羰基的有利于空间共轭效应的超支化聚硅氧烷，分析其化学结构与发光性能的关系。接着，以酰胺化反应接枝β-环糊精刚性单元和聚醚柔性链段，通过刚柔相济单元的协同作用形成多重氢键，进一步调控其自组装行为，构筑具有温度、pH双重响应型高荧光强度的超分子超支化聚硅氧烷；研究其自组装体的微观结构、形貌与发光性能之间的关系，揭示其荧光增强机制；探究其在药物控释及细胞成像方面的应用，为设计智能型高荧光强度的非芳香族发光聚合物提供理论依据，为药物控释“可视化”奠定基础。

针对非芳香族聚集诱导发光（AIE）聚合物存在荧光强度不高、刺激响应性单一、功能性不足以及缺乏系统发光理论等问题，本项目在国家自然基金（21875188）的资助下，首先设计合成一类具有空间共轭效应的含羰基超支化聚硅氧烷，分析了其化学结构与发光性能的构效关系；并将疏水性不同的化合物（β-环糊精、油酸、谷氨酸、精氨酸等）接枝到超支化聚硅氧烷的端位，构筑了结构不同的超支化聚硅氧烷衍生物，通过构筑“多重氢键”与“亲疏水效应”来调控超支化聚硅氧烷的自组装行为和聚集状态，使其具有温度、pH及溶剂响应行为和多色发光、高量子产率等发光特征，并赋予其细胞成像和药物控释“可视化”的功能。并且，结合密度泛函理论（DFT）分析，揭示了超支化聚硅氧烷及其衍生物的化学结构与发光性能之间的构效关系，提出了“硅桥增强发光”、“多环诱导多色”以及“共振能量转移诱导多发射和增强荧光”等发光机理，为设计发光优异性能的非传统荧光聚合物奠定了理论依据，也为超支化聚硅氧烷在癌症诊疗中的应用奠定了良好基础，并拓宽了其在离子检测、防伪加密、树脂改性中的应用。在Angew. Chem. Inter. Ed., Macromolecules, Biomacromolecules等期刊发表论文22篇，申请并获授权国家发明专利8项，培养博士研究生4名（3名已毕业），硕士研究生7名（均已毕业）；参加国际国内会议9次，圆满完成了项目研究目标。