Distinctive Viewpoint on the Rapid Dissolution Mechanism of α-Chitin in Aqueous Potassium Hydroxide-Urea Solution at Low Temperatures
Distinctive Viewpoint on the Rapid Dissolution Mechanism of α-Chitin in Aqueous Potassium Hydroxide-Urea Solution at Low Temperatures
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DOI：
10.1021/acs.macromol.0c00945
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发表时间：
2020-07-14
期刊：
影响因子：
5.5
通讯作者：
Cai, Jie
中科院分区：
文献类型：
--
作者：
Huang, Junchao;Zhong, Yi;Cai, Jie
为了开发一种用于溶解甲壳素的绿色溶剂，必须阐明其机理的最基本方面。在这项工作中，利用 KOH/尿素水溶液快速溶解 α-甲壳素，无需进行冻融循环。研究发现，α-甲壳素溶解的机制不仅涉及其结晶区域和分级结构的快速扩展，还涉及K+离子与甲壳素羰基氧之间直接而强烈的相互作用。 K+水化壳相对较高的柔韧性和可变形性允许水分子和羰基氧之间的快速交换，从而诱导强分子间和分子内氢键的断裂，导致甲壳素晶体快速膨胀和破坏以及α-甲壳素的溶解。此外，额外的尿素减轻了几丁质链的疏水性，从而防止了自聚集并增加了几丁质链的流动性。所描述的α-几丁质溶解机制有助于更好地理解生物大分子溶解。
To develop a green solvent for chitin dissolution, the most fundamental aspects of its mechanism must be elucidated. In this work, an aqueous KOH/urea solution was utilized for the rapid dissolution of alpha-chitin without performing freeze-thaw cycles. It was found that the mechanism of alpha-chitin dissolution involved not only the fast expansion of its crystalline regions and hierarchical structure but also direct and strong interactions between K+ ions and chitin carbonyl oxygens. The relatively high flexibility and deformability of the K+ hydration shells allowed fast exchange between water molecules and carbonyl oxygens, which induced the cleavage of strong inter- and intramolecular hydrogen bonds, resulting in the rapid swelling and destruction of the chitin crystal and dissolution of alpha-chitin. Moreover, the additional urea mitigated the hydrophobicity of chitin chains, which prevented self-aggregation and increased the mobility of chitin chains. The described alpha-chitin dissolution mechanism can help achieve a better understanding of biomacromolecule dissolution.