Chitin, a fascinating biopolymer found in living organisms, fulfills current demands of availability, sustainability, biocompatibility, biodegradability, functionality, and renewability. A feature of chitin is its ability to structure into hierarchical assemblies, spanning the nano- and macroscales, imparting toughness and resistance (chemical, biological, among others) to multicomponent materials as well as adding adaptability, tunability, and versatility. Retaining the inherent structural characteristics of chitin and its colloidal features in dispersed media has been central to its use, considering it as a building block for the construction of emerging materials. Top-down chitin designs have been reported and differentiate from the traditional molecular-level, bottom-up synthesis and assembly for material development. Such topics are the focus of this Review, which also covers the origins and biological characteristics of chitin and their influence on the morphological and physical-chemical properties. We discuss recent achievements in the isolation, deconstruction, and fractionation of chitin nanostructures of varying axial aspects (nanofibrils and nanorods) along with methods for their modification and assembly into functional materials. We highlight the role of nanochitin in its native architecture and as a component of materials subjected to multiscale interactions, leading to highly dynamic and functional structures. We introduce the most recent advances in the applications of nanochitin-derived materials and industrialization efforts, following green manufacturing principles. Finally, we offer a critical perspective about the adoption of nanochitin in the context of advanced, sustainable materials.

中文翻译：

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纳米甲壳素：化学、结构、组装和应用

甲壳素是一种在生物体中发现的令人着迷的生物聚合物，满足当前对可用性、可持续性、生物相容性、生物可降解性、功能性和可再生性的需求。甲壳素的一个特点是它能够构建成跨越纳米和宏观尺度的分层组件，赋予多组分材料韧性和耐受性（化学、生物等），并增加适应性、可调性和多功能性。保留甲壳素的固有结构特征及其在分散介质中的胶体特征一直是其使用的核心，将其视为构建新兴材料的基石。自上而下的甲壳素设计已被报道，它与材料开发中传统的分子水平、自下而上的合成和组装不同。这些主题是本综述的重点，本综述还涵盖了甲壳素的起源和生物学特性及其对形态和物理化学性质的影响。我们讨论了不同轴向方面的几丁质纳米结构（纳米原纤维和纳米棒）的分离、解构和分级方面的最新成就，以及将其修饰和组装成功能材料的方法。我们强调纳米几丁质在其天然结构中的作用以及作为受到多尺度相互作用的材料的组成部分的作用，从而产生高度动态和功能性的结构。我们遵循绿色制造原则，介绍纳米甲壳素衍生材料的应用和产业化工作的最新进展。最后，我们提供了关于在先进、可持续材料背景下采用纳米甲壳素的批判性观点。