Physically cross-linked scaffold composed of hydroxyapatite-chitosan-alginate-polyamide has potential to trigger bone regeneration in craniofacial defect

Recently, the fabrication of a scaffold from biomaterials has been increased due to the lack of adequate natural bone for grafting. In this study, hydroxyapatite-chitosan-alginate-polyamide (HCAP) synthetic scaffold was fabricated using the thermally induced phase separation (TIPS) technique. The scaffold was cross-linked with either a chemical cross-linker (calcium chloride, 2-hydroxyethyl methacrylate (HEMA), or glutaraldehyde (GTA)) or a physical cross-linker (gamma irradiation (IR)) resulting in scaffolds HCAP-CaCl2, HCAP-HEMA, HCAP-GTA, and HCAP-IR, respectively. The cross-linked scaffolds were characterized based on physicochemical properties, cytotoxicity, and biocompatibility. HCAP-GTA showed the highest density and the lowest swelling ratio and biodegradation rate closely matching with those of the HCAP-IR. Porosity and density of the HCAP, HCAP-IR, and HCAP-GTA scaffolds were 92.14, 87.26, and 83.33 %, and 0.241, 0.307, and 0.335 g/cm3, respectively. The swelling ratio for the same scaffolds was 149, 110, and 108 % after 72 h of observation. Brine shrimp cytotoxicity and RBC biocompatibility assay confirmed the non-toxic nature of HCAP-IR and HCAP-GTA scaffolds. The HCAP-IR scaffold was tested for bone regeneration in the rabbit mandible defect model. Histological analysis revealed the regeneration of new bone and restoration of bone defect at the site of injury. These findings indicate that radiation induced physically cross-linked HCAP scaffold could be used as an alternative in bone defect replacement therapy.