生物大分子辅助的有机无机纳米复合水凝胶的制备及性能集成

To enhance the mechanical strength of common hydrogels, researchers provide some novel approaches to fabricate tough hydrogels, such as double-network hydrogel and clay nanocomposite hydrogel. Although these hydrogels have perfect mechanical performance, functional nanoparticles could not be merged into hydrogel framework with remained toughness. The unresolved technical issues for fabricating functional nanoparticle-crosslinking nanocomposite hydrogel include the weak binding of polymer chains with nanoparticles and the lack of crosslinking points due to low dispersion of nanoparticles. Our project provides a new design of functional nanocomposite hydrogel to overcome these two weaknesses. Firstly, we will use the multiple salt bridge of guanidinium ion in polymer side chain with acid radical within crosslinking point as the gelation force. Secondly, the different types of free radical polymerization will be selected as the gelation approaches. Finally, two gelation processes, including direct crosslink and continued exfoliation-crosslink, will be designed according to the various situations of the biomolecules-nanosheets collective crosslinking points. The resulted three-component hydrogel has both functional nanosheets and non-covalent conjugated biomolecules, whose cooperative effect will enhance both the electron-transfer during enzyme biosensor and the stability of biocatalysis. As an integration of strength, bioactive enzyme and electrochemical properties, this kind of soft-wet hydrogel platform can be applied in hydrogel-immobilized enzyme electrode and heterogeneous biocatalysis.

为提高普通水凝胶的力学强度，研究者们从网络结构和交联点两个方向着手提出了一些构筑高强凝胶的新途径，如双重网络凝胶和粘土纳米复合凝胶。这些凝胶尽管力学性能突出，但都不能在骨架中融入功能性的纳米颗粒。当前构建功能纳米颗粒交联凝胶的技术障碍包括高分子链与纳米颗粒结合弱以及纳米颗粒低分散下的交联点缺乏，本项目从这两点出发进行功能复合凝胶的设计。首先我们以高分子侧链胍离子和交联点酸根离子的多重盐桥为成胶驱动力，用不同类型自由基引发的聚合为成胶途径，最后根据生物大分子助剂与纳米片复合交联点形态的不同来设计直接交联和剥离再交联两种成胶工艺。所得三元复合凝胶中既有功能纳米片也有非共价负载的生物分子，两者的协同作用能优化酶传感过程的电子转移和催化稳定性。集成强度、活性酶和电化学性能于一体的软湿水凝胶体系可望应用于凝胶酶电极和非均相生物催化。

在项目的资助下，课题组利用生物大分子的催化作用在生理条件下生成自由基实现高分子复合凝胶的制备，该方法为生物友好的负载细胞和生物分子提供可能。研究表明温和的酶促自由基聚合能赋予成胶前驱体可调的粘度，该体系凝胶适宜于作为3D打印成型的墨汁以获得不同形貌和尺寸凝胶来满足未来器官打印的需求。同时，通过不同尺寸的模板晶体可以构筑具有多级孔结构的复合凝胶，提高小分子的扩散速率，为负载不同尺寸的客体提供通透的微环境。这些结果说明了课题组发展的多级孔高分子复合凝胶在生物医学和柔性器件等领域的潜在应用性。在4年的项目支持期间，课题组发表SCI收录论文31篇，研究成果获得国际国内同行的认可。