Chitosan is the second-most abundant natural polysaccharide. It has unique characteristics, such as biodegradability, biocompatibility, and non-toxicity. Due to the existence of its free amine group and hydroxyl groups on its backbone chain, chitosan can undergo further chemical modifications to generate Chitosan Derivatives (CDs) that permit additional biomedical functionality. Chitosan and CDs can be fabricated into various forms, including Nanoparticles (NPs), micelles, hydrogels, nanocomposites and nano-chelates. For these reasons, chitosan and CDs have found a tremendous variety of biomedical applications in recent years. This paper mainly presents the prominent applications of chitosan and CDs for cancer therapy/diagnosis, molecule biosensing, viral infection, and tissue engineering over the past five years. Moreover, future research directions on chitosan are also considered.

壳聚糖是第二丰富的天然多糖。它具有独特的特性，例如生物降解性，生物相容性和无毒性。由于其主链上存在游离胺基和羟基，壳聚糖可以进行进一步的化学修饰以生成壳聚糖衍生物（CDs），该衍生物具有附加的生物医学功能。壳聚糖和CD可以制成各种形式，包括纳米颗粒（NPs），胶束，水凝胶，纳米复合材料和纳米螯合物。由于这些原因，壳聚糖和CD近年来已发现了各种各样的生物医学应用。本文主要介绍了壳聚糖和CD在过去五年中在癌症治疗/诊断，分子生物传感，病毒感染和组织工程中的重要应用。此外，