Chitosan is formed by chitin deacetylation and consists of -(1-4)-linked d-glucosamine and N-acetyl-d-glucosamine. Since this polycationic polysaccharide contains glucosamine and N-acetylglucosamine molecules, chitosan has a high degree of structural similarity to natural glycosaminoglycans (GAG). Chitosan bioink has been investigated for various tissue engineering applications and drug delivery in recent years due to its high biocompatibility and biodegradability, low immunogenicity and cationic nature. In addition, because of its unique hemostatic and anti-infective activity, chitosan bioink is regarded as wound healing promoter and widely employed in wound healing application.

However, unmodified chitosan can dissolve in acidic solutions due to strong intermolecular hydrogen bonds; this limits its use as an injectable hydrogel. Chitosan is functionalized with methacrylic anhydride so that the polymer can be photo crosslinked through chain-growth, step-growth, or a combination of both mechanisms referred to as mixed mode.