Chitin is one of the most abundant biopolymers, and it has adopted many different structural conformations using a combination of different natural processes like biopolymerization, crystallization and non-equilibrium self-assembly. This leads to a number of striking physical effects like complex light scattering and polarization as well as unique mechanical properties. In doing so, chitin uses a fine balance between the highly ordered chain conformations in the nanofibrils and random disordered structures. In this opinion piece, we discuss the structural hierarchy of chitin, its crystalline states and the natural biosynthesis processes to create such specific structures and diversity. Among the examples we explored, the unified question arises from the generation of completely different bioarchitectures like the Christmas tree-like nanostructures, gyroids or helicoidal geometries using similar dynamic non-equilibrium growth processes. Understanding the in vivo development of such structures from gene expressions, enzymatic activities as well as the chemical matrix employed in different stages of the biosynthesis will allow us to shift the material design paradigms. Certainly, the complexity of the biology requires a collaborative and multi-disciplinary research effort. For the future's advanced technologies, using chitin will ultimately drive many innovations and alternatives using biomimicry in materials science.

This article is part of the theme issue ‘Bio-derived and bioinspired sustainable advanced materials for emerging technologies (part 1)'.

甲壳素是最丰富的生物聚合物之一，它结合了生物聚合、结晶和非平衡自组装等不同的自然过程，采用了许多不同的结构构象。这导致了许多引人注目的物理效应，例如复杂的光散射和偏振以及独特的机械性能。在此过程中，甲壳素利用了纳米原纤维中高度有序的链构象和随机无序结构之间的良好平衡。在这篇评论文章中，我们讨论了甲壳素的结构层次、其结晶状态以及创造这种特定结构和多样性的自然生物合成过程。在我们探索的例子中，统一的问题来自于使用类似的动态非平衡生长过程生成完全不同的生物结构，例如圣诞树状纳米结构、陀螺仪或螺旋几何结构。从基因表达、酶活性以及生物合成不同阶段使用的化学基质了解此类结构的体内发育将使我们能够改变材料设计范式。当然，生物学的复杂性需要协作和多学科的研究努力。对于未来的先进技术，使用甲壳素将最终推动材料科学中仿生学的许多创新和替代方案。

本文是主题“新兴技术的生物衍生和生物启发可持续先进材料（第 1 部分）”的一部分。