Biomimetic cryogels based on carboxymethyl chitosan/gelatin/hydroxyapatite for bone tissue engineering

Gelation at temperature below freezing point of solvent is known as cryogelation that attracted attention in regenerative medicine due to improved mechanical and structural properties. This study focuses on using cryogelation as a versatile method for fabricating biomimetic scaffolds with improved mechanical strength and larger pore size with potential for bone tissue engineering applications. These scaffolds comprising carboxymethyl-chitosan/gelatin/ nano-hydroxyapatite were formed via cryogelation. The effects of three parameters, including crosslinker concentration, mineral content and gelatin-to-polymer ratio, were investigated on the physical, chemical and mechanical properties. In this work, MG63 cells were used for in vitro assay. In addition, in vivo assay was conducted to investigate the biocompatibility of nanocomposite scaffolds. The results showed that all scaffolds have a porous structure with interconnected pores with morphology similar to bone structure. Their pore size, porosity, and swelling ratio decreased with increased crosslinker concentration, while nano-hydroxyapatite has the opposite effect. XRD results also showed that the inorganic phase retained its crystallinity in the substrate with a slight decrease in crystal size. In addition, the scaffold showed no toxicity in either in vitro or in vivo studies. Obtained results showed that the biomimetic cryogels based on carboxymerthyl chitosan/gelatin/hydroxyapatite has a potential for bone tissue engineering.