Abstract:Chitosan is derived primarily from shrimp and crab shells. Expanding use of chitosan can promote the recycling of shrimp and crab shell waste while advancing green biotechnology. Chitosan and its derivatives exhibit a wide range of biological activities, including tissue repair, regeneration, and promoting coagulation and have antibacterial, anticancer, antioxidant, and absorption properties. Despite its excellent characteristics, chitosan has limitations, such as poor solubility and weak mechanical properties. The development of nanotechnology has provided a foundation for broadening the applications of chitosan. Chitosan-based nanocomposites are formed by introducing nanoscale inorganic or organic substances into chitosan, which serves as the matrix. Recently, chitosan-based nanocomposites have become the focus of research in various fields owing to their biocompatibility, degradability, and multifunctionality. In the medical field, chitosan nanocomposites can promote wound healing by enhancing epithelialization and collagen deposition in the dermis and are promising candidates for bone and cartilage regeneration. Furthermore, chitosan nanocomposites can deliver encapsulated drugs via various pathways; their nanoscale structure significantly improves the drugs’ bioavailability and targeting. Chitosan and its derivatives possess strong heavy metal adsorption capabilities in wastewater and pollutant treatment, owing to their multifunctional chemical groups, high hydrophilicity, high chemical reactivity, and flexible polymer structures. Chitosan nanocomposites can enhance these properties by improving their mechanical strength, stability, reusability, and adsorption capacity. In agriculture, chitosan nanocomposites are used as functional components in plant growth inducers, pesticide carriers, fertilizers, growth regulators, and stress inhibitors owing to their enhanced antimicrobial properties, targeting ability, and controlled release features. In the food industry, the antimicrobial, mechanical, and barrier properties of films and coatings can be improved by incorporating nanomaterials into chitosan, which enhances food quality and extends shelf life. In the fishery industry, chitosan nanocomposites serve as carriers, encapsulants, and immobilizers for bioactive ingredients, enabling the oral delivery of drugs, vitamins, nutrients, genes, and vaccines to the fish gastrointestinal tract. This paper systematically reviews the research progress and application potential of chitosan-based nanocomposites across the fields of medicine, agriculture, wastewater treatment, food, and fisheries to provide a comprehensive reference and foundation for expanding the applications of chitosan.
