A review of chitosan and its derivatives in bone tissue engineering

•Chitosan is studied for bone regeneration applications owing to its tunable chemical and biological properties.•It has limitations including its water insolubility, lack of mechanical strength and weak antimicrobial property.•Chitosan with other polymers and ceramics (hydroxyapatite, bioglass ceramic) improves its applications in bone regeneration.•Functionalization of chitosan structure through chemical modifications also provides a solution to these limitations.•Modifications of chitosan such as quaternization, carboxyalkylation, and phosphorylation are studied in bone tissue engineering. Critical-sized bone defects treated with biomaterials offer an efficient alternative to traditional methods involving surgical reconstruction, allografts, and metal implants. Chitosan, a natural biopolymer is widely studied for bone regeneration applications owing to its tunable chemical and biological properties. However, the potential of chitosan to repair bone defects is limited due to its water insolubility, faster in vivo depolymerization, hemo-incompatibility, and weak antimicrobial property. Functionalization of chitosan structure through various chemical modifications provides a solution to these limitations. In this review, current trends of using chitosan as a composite with other polymers and ceramics, and its modifications such as quaternization, carboxyalkylation, hydroxylation, phosphorylation, sulfation and copolymerization in bone tissue engineering are elaborated.