Chitooligosaccharides (COS) differ from chitosan by their molar mass: those of COS are defined to be lower than 20 kg mol⁻¹. Their functionalization is widely described in the literature and leads to the introduction of new properties that broaden their application fields. Like chitosan, COS modification sites are mainly primary amine and hydroxyl groups. Among their chemical modification, one can find amidation or esterification, epoxy-amine/hydroxyl coupling, Schiff base formation, and Michael addition. When depolymerized through nitrous deamination, COS bear an aldehyde at the chain end that can open the way to other chemical reactions and lead to the synthesis of new interesting amphiphilic structures. This article details the recent developments in COS functionalization, primarily focusing on amine and hydroxyl groups and aldehyde-chain end reactions, as well as paying considerable attention to other types of modification. We also describe and compare the different functionalization protocols found in the literature while highlighting potential mistakes made in the chemical structures accompanied with suggestions. Such chemical modification can lead to new materials that are generally nontoxic, biobased, biodegradable, and usable in various applications.

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壳寡糖化学修饰研究进展

壳寡糖 (COS) 与壳聚糖的摩尔质量不同：COS 的摩尔质量定义为低于 20 kg mol ^-1. 它们的功能化在文献中得到了广泛的描述，并导致引入了拓宽其应用领域的新特性。与壳聚糖一样，COS 的修饰位点主要是伯胺和羟基。在它们的化学改性中，可以发现酰胺化或酯化、环氧-胺/羟基偶联、席夫碱形成和迈克尔加成。当通过亚硝酸脱氨解聚时，COS 在链端带有一个醛，可以为其他化学反应开辟道路并导致合成新的有趣的两亲结构。本文详细介绍了 COS 功能化的最新进展，主要关注胺和羟基以及醛链末端反应，以及对其他类型的修饰相当关注。我们还描述和比较了文献中发现的不同功能化协议，同时强调了化学结构中可能出现的错误并附有建议。这种化学改性可以产生通常无毒、生物基、可生物降解和可用于各种应用的新材料。