Feng Xiaoqing, Liu Jie, Xu Gang, Zhang Xiacong, Su Xinyan, Li Wen, Zhang Afang
Department of Polymer Materials, College of Materials Science and Engineering, Shanghai University, Materials Building Room 801, Nanchen Street 333, Shanghai 200444, China.
J Mater Chem B. 2018 Apr 7;6(13):1903-1911. doi: 10.1039/c7tb03352d. Epub 2018 Mar 9.
A series of double-network cryogels (DNCs) were prepared from oligoethylene glycol (OEG)-based dendronized copolymers as the first network and polyvinyl alcohol (PVA) as the second network. The dendronized copolymers were composed of dendritic OEG units, as well as triethoxysilyl, amine or carboxyl groups. The dendritic OEGs ensured characteristic thermoresponsiveness and triethoxysilyl groups were for crosslinking, while amino and carboxyl groups were designed to provide charged species for specifically interacting with proteins. PVA behaves as a mutual support which ensures the stability and mechanical properties of the cryogels. These DNCs exhibited good thermoresponsiveness and biocompatibility. Upon increasing the temperature above their cloud points (Ts), the cryogels became dehydrated with enhanced hydrophobicity, and thus their porous structures shrank. This property was utilized to mediate encapsulation and release of proteins. The loading and release efficiencies of different proteins were found to be dominated by hydrophilic to hydrophobic transitions of the first network, and at the same time, by the properties of proteins. At room temperature, the cryogel could efficiently capture model proteins, while above Ts, more than 80% of lysozyme could be released in 24 h with enzyme activity remaining unchanged. These series of smart cryogels based on thermoresponsive dendronized copolymers may provide promising applications for the reversible capture of enzymes or proteins.
一系列双网络冷冻凝胶（DNCs）由基于低聚乙二醇（OEG）的树枝状共聚物作为第一网络和聚乙烯醇（PVA）作为第二网络制备而成。树枝状共聚物由树枝状OEG单元以及三乙氧基甲硅烷基、胺基或羧基组成。树枝状OEG确保了特征性的热响应性，三乙氧基甲硅烷基用于交联，而氨基和羧基则旨在提供带电物种以与蛋白质特异性相互作用。PVA起到相互支撑的作用，确保冷冻凝胶的稳定性和机械性能。这些DNCs表现出良好的热响应性和生物相容性。当温度升高到其浊点（Ts）以上时，冷冻凝胶脱水，疏水性增强，因此其多孔结构收缩。这一特性被用于介导蛋白质的包封和释放。发现不同蛋白质的负载和释放效率受第一网络从亲水性到疏水性转变的主导，同时也受蛋白质性质的影响。在室温下，冷冻凝胶可以有效地捕获模型蛋白质，而在Ts以上，超过80%的溶菌酶可以在24小时内释放，酶活性保持不变。这些基于热响应性树枝状共聚物的智能冷冻凝胶系列可能为酶或蛋白质的可逆捕获提供有前景的应用。
