Mechanical properties and osteogenesis of CFR-PEEK composite with interface strengthening by graphene oxide for implant application

In this work, 1 wt% of graphite oxide (GO) was used to strengthen the interface of carbon fibers (CF) reinforced polyetheretherketone (CFR-PEEK) composites, so as to obtain sufficiently high mechanical properties and bioactive surfaces which are two fundamental requirements for orthopedic/dental implants. Concretely, aminated GO was grafted onto oxidized CF in aqueous solution in a mild and non-toxic manner, subsequently, the CF grafted by GO was used for injection molding to prepare CFR-PEEK implant. The dispersibility of CF in the composites were remarkably boosted. Mechanical tests indicated that the flexural strength, compressive strength and hardness of CFR-PEEK were increased by 51%, 46%, and 30%, respectively. Furthermore, the flexural modulus increased to 11.67 ± 0.20 GPa and the compression modulus increased to 6.12 ± 0.11 GPa, which both meet the elastic modulus of human bone (6-30 GPa). The wear resistance was slightly improved. In the in vitro cell evaluation, CFR-PEEK with interface strengthening by GO showed no cytotoxicity and exhibited significantly enhanced adhesion and proliferation of Bone marrow mesenchymal stem cells (BMSCs) on the surface. More importantly, osteogenesis-related protein expression in vitro and osteogenetic evaluation in vivo all disclosed greatly accelerated osteo-differentiation of BMSCs on the composites due to the additive effect of GO at the interface. Based on this scheme, the CFR-PEEK composites with the dual functions of mechanical enhancement and osteointegration promotion holds great potential as implants in orthopedic/dental applications.