Preparation and characterization of reduced graphene oxide/fluorhydroxyapatite composites for medical implants

Poor mechanical properties and a relatively low stability in physiological environments have significantly limited hydroxyapatite (HA) for many practical implant applications. In this study, we developed a reduced graphene oxide/fluorhydroxyapatite (rGO/FHA) biocomposite with enhanced mechanical properties, dissolution resistance, biocompatibility and antibacterial activity. rGO and fluorine (F) are simultaneously incorporated into HA to form the rGO/FHA composite by an in situ chemical synthesis method and spark plasma sintering technology. The uniform distribution of rGO and the good interfacial bonding help to improve the hardness by 86% and the fracture toughness by 137%. The chemical stability of the rGO/FHA composite is evaluated by determining the Ca2+ ion release. The result indicates that the substitution of F− ions into the HA structure has a positive effect on the dissolution resistance of HA. The in vitro bioactivity assessment shows that the osteoblast adhesion and proliferation ability on the rGO/FHA composite are improved. In addition, a higher alkaline phosphate activity is also detected in cells cultured on the rGO/FHA composite. More importantly, it is observed that the rGO/FHA composite can effectively inhibit the adhesion and proliferation of Streptococcus mutans. These findings suggest that the rGO/FHA biocomposite would be highly useful as a dental implant material.