壳聚糖因其产量丰富, 同时具有生物安全性、可降解性和抗菌抗炎等特性, 而受到医疗行业广泛关注。但是壳聚糖的水溶性较差, 限制了其应用。将壳聚糖改性, 制备成可溶于水的壳聚糖水凝胶, 例如可光固化交联的水凝胶, 可使其广泛应用于细胞培养、组织工程、3D打印等领域。在光固化交联中, 巯基-降冰片烯点击反应因其极高的反应速率而值得被关注。本研究通过改变反应参数包括反应物的量、反应时间和反应体系酸碱度三个物理量, 制备了一系列降冰片烯改性壳聚糖水凝胶, 并提出了使用核磁共振氢谱技术来表征其取代率的计算方法。研究发现, 在壳聚糖改性的反应体系中同时发生取代反应和酸酐水解反应, 两个反应相互影响, 对反应参数的综合调节可以调控反应速率以及产物的取代率, 本研究的取代率可在9%~43%范围内变化。本研究中的降冰片烯改性壳聚糖水凝胶具有超过50%的吸水率, 其优秀的吸水能力使其可以应用于伤口敷料、药物递送等领域。

Chitosan has attracted widespread attention in the medical industry because of its abundant yield, biocompatibility, biodegradability, antibacterial and anti-inflammatory properties. However, chitosan shows limited water solubility, preventing its development. To functionalize chitosan to water-soluble chitosanbased hydrogels, such as photo-curable hydrogels, which can be widely used in cell culture, tissue engineering, 3D printing and other fields. In the field of photocuring reactions, the thiol-norbornene click reaction is worth to be studied due to its extremely high reactivity. In this research, a family of norbornene-functionalized chitosan were prepared by changing the reaction parameters, including the amount of reactants, reaction time and pH of the system. A calculation method of degree of substitution was proposed, based on the characterization of 1H nuclear magnetic resonance spectroscopy. The research investigated that in this chitosan functionalized reaction system, the substitution reaction and the anhydride hydrolysis reaction occur simultaneously and intact, and and the two reactions affect each other The reaction rate and degree of substitution can be tailored by comprehensively adjusting the reaction parameters. The degree of substitution ranged from 9% to 43% in this research. Norbornene-functionalized chitosan was able to absorb water more than 50% in mass change, and its excellent water absorption ability can be used in the application areas of wound healing and drug delivery and other fields.