Department of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, United States.
Department of Sustainable Biomaterials, Virginia Tech, Blacksburg, Virginia 24061, United States.
Biomacromolecules. 2020 Oct 12;21(10):4261-4272. doi: 10.1021/acs.biomac.0c01046. Epub 2020 Sep 8.
Polysaccharide-based hydrogels are attractive materials for biomedical applications for reasons that include their polyfunctionality, generally benign nature, and biodegradability. However, the use of polysaccharide-based hydrogels may be limited by toxicity arising from small-molecule crosslinkers, or may involve undesired chemical modification [Hennink, W. E.; et al. 2012, 64, 223-236]. Here, we report a green, simple, efficient strategy for the preparation of polysaccharide-based, in situ forming hydrogels. The Edgar group reports in the accompanying manuscript that chemoselective oxidation of oligo(hydroxypropyl)-substituted polysaccharides introduces ketone groups at the termini of the side chains [Nichols, B. L. B.; et al]. Amine-containing moieties can condense with ketones to form imines. The imine linkage is dynamic in the presence of water, providing the potential for self-healing [Wei, Z.; et al. 2015, 25, 1352-1359], injectability [Wei, Z.; et al. 2015, 25, 1352-1359], and pH responsiveness [Yao, K.; et al. 1993, 48, 343-354]. In this work, we designed and prepared two different types of hydrogels, oxidized hydroxypropyl cellulose/chitosan (Ox-HPC-Chitosan) and oxidized hydroxypropyl dextran/chitosan (Ox-HPD-Chitosan), each cross-linked by imine bonds. The mechanical properties of these hydrogels were characterized by rheometry, revealing that hydrogel storage modulus could be tuned from 300 Pa to 13 kPa simply by controlling the degree of substitution (DS) of ketone groups. Rheological characterization also illustrated the rapid self-healing property of these all-polysaccharide hydrogels. Moreover, these hydrogels exhibited high swelling rates and facile injectability. Therefore, this work reveals a potential strategy for the construction of hydrogels that require no small-molecule crosslinkers and are therefore highly attractive for biomedical, agricultural, controlled release, and other applications.
多糖基水凝胶是一种有吸引力的生物医学应用材料，原因包括其多功能性、通常的良性性质和可生物降解性。然而，多糖基水凝胶的使用可能会受到小分子交联剂引起的毒性的限制，或者可能涉及不期望的化学修饰[Hennink, W. E.; et al. 2012, 64, 223-236]。在这里，我们报告了一种绿色、简单、高效的制备多糖基原位形成水凝胶的策略。Edgar 小组在随附的手稿中报告称，寡（羟丙基）取代多糖的选择性氧化在侧链末端引入酮基[Nichols, B. L. B.; et al]。含胺部分可以与酮缩合形成亚胺。在存在水的情况下，亚胺键是动态的，为自修复提供了潜力[Wei, Z.; et al. 2015, 25, 1352-1359]、可注射性[Wei, Z.; et al. 2015, 25, 1352-1359]和 pH 响应性[Yao, K.; et al. 1993, 48, 343-354]。在这项工作中，我们设计并制备了两种不同类型的水凝胶，氧化羟丙基纤维素/壳聚糖（Ox-HPC-Chitosan）和氧化羟丙基葡聚糖/壳聚糖（Ox-HPD-Chitosan），它们均通过亚胺键交联。流变学特性研究表明，通过控制酮基的取代度（DS），可以将这些水凝胶的储能模量从 300 Pa 调至 13 kPa。流变学特性研究还说明了这些全多糖水凝胶的快速自修复特性。此外，这些水凝胶还具有高溶胀率和易于注射的特点。因此，这项工作揭示了一种构建无需小分子交联剂的水凝胶的潜在策略，因此非常适合生物医学、农业、控制释放等应用。
