Freeze-drying synthesis, characterization and in vitro bioactivity of chitosan/graphene oxide/hydroxyapatite nanocomposite

Polycrystalline and dispersed hydroxyapatite (HAP) nanoparticles were successfully prepared via a simple precipitation method with the aid of a new capping agent based on Schiff base compounds. After that, a composite of chitosan (CT), graphene oxide (GO) and HAP nanoparticles was synthesized by a freeze-drying method. The as-produced Schiff base, HAP nanoparticles, and CT/GO/HAP nanocomposite were analysed by several techniques including FTIR, SEM, HR-TEM, and XRD. In addition, the in vitro bioactivity of HAP nanoparticles and the CT/GO/HAP nanocomposite was evaluated by soaking them in simulated body fluid (SBF). By monitoring the changes of chemical composition of the SBF solutions, it was concluded that more Ca and P ions were released from the CT/GO/HAP nanocomposite compared to the pure HAP nanoparticles, indicating a high bioactivity of the nanocomposite. The SEM images showed that the formation and growth of apatite on the surfaces of the products increased after immersion for 14 days in SBF.