Fabrication and in vitro biocompatibility of sodium tripolyphosphate-crosslinked chitosan–hydroxyapatite scaffolds for bone regeneration

The aims of this study were to fabricate a novel chitosan–hydroxyapatite (CHA) scaffold crosslinked with sodium tripolyphosphate (TPP) and evaluate its in vitro biocompatibility. CHA scaffolds were fabricated via direct blending and lyophilization and further crosslinked with different concentrations (0.1 M, 0.2 M and 0.4 M) of TPP. Microstructure of TPP-CHA scaffolds was examined by using field emission scanning electron microscope. Porosity and compressive modulus of composite scaffolds were analyzed. The biodegradability of TPP-crosslinked CHA scaffolds was studied for 30 days and in vitro biocompatibility and functionality were evaluated using osteoblast-like cells, MG63, in terms of cell viability, adhesion, proliferation and early differentiation. All scaffolds showed an interconnected honeycomb-like microstructure except 0.4 M TPP-CHA scaffolds, which demonstrated the most compact and least porous structure with pore sizes of 62–185 µm. In contrast, 0.1 M TPP-CHA scaffolds exhibited the highest porosity, measured as 58.6% and pore sizes of 74–207 µm. Besides, 0.1 M TPP-CHA scaffolds also showed the lowest compressive modulus of 2.54 kPa. All TPP-crosslinked CHA scaffolds degraded to a similar extent (1.93–5.03%). Current findings revealed that 0.1 M TPP-CHA scaffolds are the most biocompatible one by promoting good cell viability with the highest adhesion, proliferation and early differentiation activities on MG63 cells among the other scaffolds. In conclusion, 0.1 M TPP-CHA scaffolds exhibited the most promising physiochemical and biocompatible properties which can be used as an alternative regenerative material for bone tissue engineering.