Preparation, properties and drug controlled release of chitin-based hydrogels: An updated review

Chitin, as the second abundant biopolymers on earth after cellulose, has been used for synthesis of hydrogels in a wide range of applications due to its biocompatibility, biodegradability and nontoxicity. This review aims to provide an overview of the latest developments in the preparation, properties and drug controlled release of chitin-based hydrogels. In the first part, the preparation of hydrogels from native chitin, nano chitin and chitin derivatives via physical or chemical procedures was discussed in detail. The properties of chitin-based hydrogels, including gel strength, swelling degree and smart response characteristics, were described in the second part. This review also introduced how chitin-based hydrogel as a drug controlled release carrier is affected by composition, pH, temperature, magnetic field, electric field and other factors. We hope this review can provide guidelines for the rational design of chitin-based hydrogels in drug delivery systems.