Quaternized chitin as biomaterial for multiple applications

Chitin, the most abundant renewable polysaccharide in the marine environment, presents restricted applications due to its low solubility. Chitin quaternization can produce a water-soluble chitin derivative with a wide pH range due to the existence of a permanent positive charge on the polymer backbone. Quaternized chitin (QC) has received increasing attention owing to its superior water solubility and antibacterial action. This review aims to outline synthesis techniques, functional materials, and multiple applications of QC. The synthesis techniques of QC, such as heterogeneous reactions and homogeneous reactions, are introduced first. Then we discuss some developed QC-based functional materials, especially micelles, hydrogels, coatings, and sponges. The progress in the applications of QC, such as wound dressings and drug/gene delivery, is also reviewed. We hope that this review can provide new inspiration for expanding the application scope of QC.