Fabrication of novel bone substitute alginate - N,O-carboxymethyl chitosan - Aldehyde hyaluronic acid - Biphasic calcium phosphate for bone regeneration

Mineralized hydrogels, synthesized by incorporating mineral particles into the hydrogel crosslinking network, have become an effective approach for bone tissue engineering. In this study, hydrogel composites based on alginate, N,O-carboxymethyl chitosan (NOCC), aldehyde hyaluronic acid (AHA) and loaded with biphasic calcium phosphate (BCP) were fabricated by in situ crosslinking. NOCC-AHA hydrogel, forming crosslinks by Schiff base reaction without requiring any chemical linkers or radial light sources, offers a porous scaffold favorable for incorporating with the mineral phase. The integration of BCP - inorganic phase - and alginate within the NOCCAHA system can be used to supplement mineral agents and reinforcement. Different amounts of BCP particles were investigated to improve cell proliferation. The formation of hydrogel composites was confirmed via scanning electron microscope (SEM), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). In vitro study evidenced that MC3T3 cells were well-attached to hydrogel composites which did not cause cytotoxicity. Furthermore, in vivo study demonstrated that alginate-NOCC-AHA-BCP hydrogels promoted bone healing in the full-thickness calvarial defect mouse model. The obtained results indicated that the fabricated hydrogel composite could be a potential material for bone regeneration with a suitable degradation rate, appropriate pore size, favorable cytocompatibility, high compressive strength, ability to support cell proliferation, and capacity to enhance bone regeneration.