Chitin, chitosan, and their derivatives

Abstract Chitosan is a deacetylated derivative of chitin obtained from the exoskeleton of shellfish, including crab, lobster, crayfish, and shrimp. Chitin can also be obtained from edible mushrooms. Chitosan and its derivatives are used in a number of health conditions, such as hypertension, obesity, high cholesterol, Crohn disease, insomnia, wound healing, periodontal disease, dry eye disease, cancer, and many others. Unique physicochemical/rheological properties of chitosan (absorption, solution stability, biodegradability, biocompatibility, nonimmunogenic activity, and nontoxicity) make them versatile for a myriad of applications in drug-delivery systems, enzyme immobilization, bioadhesive materials, vaccines, etc. These compounds also exert antimicrobial and antifungal effects, thereby having applications in agriculture and food industries. Nanoparticles (NPs) of chitosan and its derivatives offer superior results over non-NPs of chitosan in many biomedical and pharmaceutical applications. Chitosan has been approved for use in the United States, Italy, Japan, Finland, and many other countries.