Surface modification of AZ31 Mg alloy by diopside/fluorohydroxyapatite/graphene oxide nanocomposite coating: Corrosion and bioactivity evaluations

Abstract

There is a high research demand to enhance magnesium-based orthopedic implants' biocompatibility and corrosion resistance. This work reports the development of a nanocomposite ceramic coating based on diopside (Dio) / fluorohydroxyapatite (FHA) / graphene oxide (GO) via the electrophoretic deposition (EPD) method on the AZ31 Mg alloy substrate. FESEM, EDS, XRD, and FTIR were employed to characterize the physicochemical properties of the synthesized diopside and fluorohydroxyapatite ceramic nanoparticles and the EPD ceramic films. The introduction of GO in the Dio/FHA composite film eliminated pores and cracks, improved coating quality, and reduced the film thickness. AFM confirmed a decrease in surface roughness from 184.6 nm to 171.8 nm and wettability enhanced by contact angle reduction from 52.1° to 38.3°. Electrochemical polarization and EIS analyses indicated an 83% boost in corrosion resistance and a 52% reduction in corrosion current density in Dio/FHA/GO vs. Dio/FHA sample. Bioactivity evaluation after five days of immersion in simulated body fluid (SBF) was suggestive that the synergistic effect of Dio, FHA, and GO caused the most abundant apatite formation in Dio/FHA/GO film. The antibacterial activity findings showed that the Dio/FHA/GO coating could function as an antibacterial nanocomposite coating against S. Aureus and E. Coli. Overall, the Dio/FHA/GO EPD film is a highly potential ceramic biomedical coating to improve the corrosion resistance, surface properties, bioactivity, and antibacterial behavior of Mg alloys.