Construction of chitin functional materials based on a "green" alkali/urea solvent and their applications in biomedicine: Recent advance

Chitin, the nitrogen-containing polysaccharide in nature and reserves second only to cellulose, has demonstrated potential application value in multiple fields. However, under the background of various environmental problems caused by the excessive use of petroleum-based polymers, the utilization rate of this eco-friendly and renewable natural polymer is far from reaching a reasonable level. Therefore, re-searches on the green dissolution system of chitin and the preparation method of functional materials will undoubtedly lay a theoretical foundation for its large-scale promotion, which conform to the basic concept of sustainable development. This review will elaborate on the existing dissolution systems of chitin and focus on the establishment of a novel green alkali/urea dissolution system and its applica-tion in the preparation of functional materials. In this work, a series of chitin-based functional materi-als including fibers, microspheres, hydrogels, sponges, and films have been successfully prepared based on the green alkali/urea dissolution system. Furthermore, these materials were successfully applied in biomedicine such as wound healing, bone repair, cell scaffold, anti-microbial, hemostasis, cartilage repair and other fields including photoelectric, electrocatalysis and adsorption. We hope that this review can provide certain guidance for the preparation and application of chitin-based green polymer materials to promote the sustainable development of human society. (c) 2021 Elsevier Ltd. All rights reserved.