Bottom-up synthesis strategies to construct nano-architectonic material exhibiting specific properties by controlling the spatial distribution of the material units are challenging. Native polysaccharide nanocrystals, primarily cellulose and chitin nanocrystals (CNCs and ChNCs), possess excellent intrinsic biodegradability, biocompatibility, tailorable surface chemistry, and unprecedented optical and mechanical properties. These nanocrystals, in particular CNCs, have attracted considerable attention within the last years for constructing optical materials via bottom-up self-assembly. Here, the physicochemical mechanisms underlying the self-assembly of CNC nanocrystals and the structure-property relations of CNC nanocrystal assembly structures are summarized, including the transition from the isotropic phase at low concentrations to the cholesteric phase at high concentrations, and finally to dry films in a fixed state. The properties of aggregated and self-assembled CNCs are described in detail. Based on the dimensions of self-assembled structures as divided in zero-, one, two and three-dimensional constructions, recent advances of polysaccharide nanocrystals-based optical materials are discussed. Finally, the challenges of the methods for the environmentally benign preparation of polysaccharide nanocrystals are identified and the opportunities for realizing novel functional materials based on polysaccharide nanocrystal assembly are described.

通过控制材料单元的空间分布来构建具有特定性能的纳米建筑材料的自下而上的合成策略具有挑战性。天然多糖纳米晶体，主要是纤维素和甲壳素纳米晶体（CNC 和 ChNC），具有优异的内在生物降解性、生物相容性、可定制的表面化学以及前所未有的光学和机械性能。这些纳米晶体，特别是 CNC，在过去几年中通过自下而上的自组装构建光学材料引起了相当大的关注。在此，总结了CNC纳米晶自组装的物理化学机制以及CNC纳米晶组装结构的结构-性能关系，包括从低浓度的各向同性相到高浓度的胆甾相，最后到干膜的转变处于固定状态。详细描述了聚合和自组装 CNC 的特性。基于自组装结构的维度分为零维、一维、二维和三维结构，讨论了基于多糖纳米晶的光学材料的最新进展。最后，确定了环境友好的多糖纳米晶体制备方法面临的挑战，并描述了实现基于多糖纳米晶体组装的新型功能材料的机会。