Preparation and functional assessment of composite chitosan-nano-hydroxyapatite scaffolds for bone regeneration

Composite chitosan-nano-hydroxyapatite microspheres and scaffolds prepared using a co-precipitation method have shown potential for use in bone regeneration. The goal of this research was to improve the functional properties of the composite scaffolds by modifying the fabrication parameters. The effects of degree of deacetylation (DDA), drying method, hydroxyapatite content and an acid wash on scaffold properties were investigated. Freeze-dried 61% DDA scaffolds degraded faster (3.5 ± 0.5% mass loss) than air-dried 61% DDA scaffolds and 80% DDA scaffolds, but had a lower compressive modulus of 0.12 ± 0.01 MPa. Air-dried 80% DDA scaffolds displayed the highest compressive modulus (3.79 ± 0.51 MPa) and these scaffolds were chosen as the best candidate for use in bone regeneration. Increasing the amount of hydroxyapatite in the air-dried 80% DDA scaffolds did not further increase the compressive modulus of the scaffolds. An acid wash procedure at pH 6.1 was found to increase the degradation of air-dried 80% DDA scaffolds from 1.3 ± 0.1% to 4.4 ± 0.4%. All of the formulations tested supported the proliferation of SAOS-2 cells.