Fabrication of in situ crosslinking hydrogels based on oxidized alginate/N,O-carboxymethyl chitosan/β-tricalcium phosphate for bone regeneration

In this study, hydrogels based on in situ crosslinking between oxidized alginate (OA) and N,O-carboxymethyl chitosan (NOCC) in combination with β-tricalcium phosphate (β-TCP) were prepared using different OA concentrations and OA to NOCC ratios. Various hydrogel characterizations were examined and revealed the strong effect of OA concentrations and NOCC contents on the ability of hydrogel formation, swelling degree, degradability and compression strength. Besides, Schiff's base crosslinking between aldehyde groups of OA and amino groups of NOCC, indicating hydrogel formation, was confirmed via Fourier transform infrared spectroscopy (FT-IR) spectra. The presence of β-TCP in hydrogels was also confirmed by FT-IR, X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) images. Furthermore, most hydrogels were non-cytotoxic and expressed the capability for cells to penetrate, migrate and exchange nutrients and oxygen. Besides, further experiments demonstrated their in vivo biocompatibility. Generally, the results suggested that hydrogels based on 3% (w/v) OA, 3% (w/v) NOCC (OA:NOCC volume ratio is 1:3) and 20% (w/w) β-TCP have the potential for bone regeneration.