Key Laboratory of Coal Conversion and New Carbon Materials of Hubei Province School of Chemistry and Chemical Engineering, Wuhan University of Science and Technology, Wuhan 430081, China.
Zhongnan Hospital of Wuhan University, Institute of Hepatobiliary Diseases of Wuhan University, Transplant Center of Wuhan University, Hubei Key Laboratory of Medical Technology on Transplantation, Wuhan 430071, China.
Carbohydr Polym. 2020 Jan 1;227:115345. doi: 10.1016/j.carbpol.2019.115345. Epub 2019 Sep 19.
Chitin is the second most abundant natural polysaccharide with biocompatibility, biodegradability, and bioactivity. Homogeneous modification of chitin is an efficient way to improve or to impart new properties to chitin. Here, amide-modified β-chitin (AMC), hydroxyethyl β-chitin (HEC), and hydroxybutyl β-chitin (HBC) through Michael addition, Williamson reaction, and ring-opening addition, were homogeneously synthesized from aqueous KOH/urea solution, respectively, with controlled structures and uniform properties. The reactions mainly occur at the hydroxyl groups of C-6 positions of β-chitin chains due to mild conditions, and the obtained β-chitin derivatives with high DS values are water-soluble. AMC could transform from sol to gel at acidic condition or upon adding Fe due to the presence of partial carboxylate groups. As a specific highlight, HEC and HBC could thermally form smart hydrogels at physiological temperature, with cytocompatibility and blood biocompatibility, which is very useful as drug/ cell carriers for biomedical applications. The remarkably mild and "green" condition of aqueous KOH/urea solution for the synthesis of chitin derivatives has pioneered a better way to exploit its great diversity of the natural, sustainable polysaccharide.
甲壳素是生物相容性、可生物降解性和生物活性第二丰富的天然多糖。甲壳素的均相修饰是一种有效提高或赋予甲壳素新性能的方法。在这里，通过迈克尔加成、威廉姆逊反应和开环加成，分别从水性 KOH/尿素溶液中均相合成了酰胺修饰的β-甲壳素（AMC）、羟乙基β-甲壳素（HEC）和羟丁基β-甲壳素（HBC），其结构可控，性能均匀。由于条件温和，反应主要发生在β-甲壳素链 C-6 位的羟基上，并且由于 DS 值较高，所得的β-甲壳素衍生物具有水溶性。由于存在部分羧酸根，AMC 在酸性条件下或加入 Fe 时可以从溶液转变为凝胶。作为一个特别的亮点，HEC 和 HBC 可以在生理温度下热形成智能水凝胶，具有细胞相容性和血液生物相容性，非常适合用作生物医学应用的药物/细胞载体。水性 KOH/尿素溶液中温和且“绿色”的条件用于合成甲壳素衍生物，开创了一种更好的方法来开发这种天然、可持续多糖的多样性。
