A new biomaterial, a hydrogel, with dual-crosslinked design, has been created with enhanced mechanical performance. The hydrogels are fabricated based on water-soluble chitosan, with dual-crosslinking of imine linkages and host–guest interactions. Phenolphthalein-grafted N-carboxyethyl chitosan (CECS-g-PHP), as a guest polymer, is synthesized and structurally characterized and complexed with hexamethylenediamine modified β-cyclodextrin (β-CD-HDA), as a host molecule. Oxidized sodium alginate (OSA) is added to form crosslinking networks via imine linkages with the existing amino groups. The hydrogels show significantly shorter gelation times and higher compressive stresses, compared with single-crosslinked hydrogels. The phenolphthalein units in the hydrogel change color with pH and other added chemicals. Moreover, the hydrogels can be injected and are self-healing with >80% recovery within 4 h. Thus, these dual-crosslinked hydrogels, which respond to pH and other stimuli, are promising designs for new multifunctional biomaterials.

中文翻译：

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来自酚酞接枝 N-羧乙基壳聚糖的双交联设计的刺激响应、自愈和可注射水凝胶

一种新的生物材料，一种具有双交联设计的水凝胶，具有增强的机械性能。水凝胶是基于水溶性壳聚糖制造的，具有亚胺键的双重交联和主客体相互作用。酚酞接枝氮-羧乙基壳聚糖（CECS-g-PHP）作为客体聚合物，被合成和结构表征并与六亚甲基二胺改性的β-环糊精（β-CD-HDA）复合，作为主体分子。添加氧化海藻酸钠 (OSA) 以通过与现有氨基的亚胺键形成交联网络。与单交联水凝胶相比，水凝胶显示出明显更短的凝胶时间和更高的压缩应力。水凝胶中的酚酞单元会随着 pH 值和其他添加的化学物质而改变颜色。此外，水凝胶可以注射并在 4 小时内自我修复 > 80% 的恢复。因此，这些对 pH 值和其他刺激做出反应的双交联水凝胶是新型多功能生物材料的有前途的设计。