海藻酸动态共价交联水凝胶的制备及其自愈合性能

Alginate-based Self-healing and p H-responsive Hydrogels Formed by Dynamic Covalent Bonding

利用高碘酸钠氧化海藻酸得到带有醛基的海藻酸,利用水合肼与聚乙二醇反应得到末端为酰肼基的聚乙二醇,以二者为原料利用醛基与酰肼基反应形成酰腙键的动态化学反应,赋予天然生物大分子水凝胶优良的自愈性和p H响应性.通过红外光谱、核磁共振光谱、动态黏弹谱、电子万能试验机等表征了材料的结构、水凝胶的自愈合能力以及p H响应性.结果表明,该水凝胶具有良好的力学性能和自愈合能力,能够在不加热和不添加催化剂的情况下,在温和的生理环境下自发实现切口愈合.同时水凝胶具有p H响应性,在碱性环境中成凝胶,在酸性环境中则转变为溶液状态,并且这种凝胶—溶液转变可重复多次.这些优异的性能,加上简单的制备方法、良好的生物相容性将为这类材料在生物医用领域的应用提供坚实的基础.

A self-healable hydrogel was prepared by self-crosslinking two biocompatible materials oxidized alginate containing dialdehyde groups and PEG with acylhydrazine groups. Oxidation reactions on —OH groups at C-2 and C-3 positions of the uronic units of sodium alginate were performed with sodium periodate. PEG with acylhydrazine terminals was synthesized by PEG and hydrazine hydrate. The generation of the self-crosslinked hydrogel relies on the dynamic covalent linkage through acylhydrazone bonds. Fourier transform infrared spectroscopy（ FTIR）,nuclear magnetic resonance（ NMR）,universal testing machine and rheometer were used to characterize the structure and properties of the hydrogel. The results demonstrate that the hydrogel has good flexibility and mechanical strength. The gelation time and mechanical properties can be adjusted by the polymer concentration. The hydrogel can repair itself under mild physiological condition without adding any agent. In both of compression and tensile tests,about 90% recovery of stresses was achieved after healing for 24 h. In addition,the p H responsive hydrogel may undergo gel-sol transition by adjusting p H value of the environment and the transition can be repeated several times. The combination of self-healing,p H sensitive,biocompatibility,along with an easy method of synthesis,made this material ideal candidate for further biomedical applications.