A promising orthopedic implant material with enhanced osteogenic and antibacterial activity: Al₂O₃-coated aluminum alloy

Better orthopedic implants improve the life quality of patients and elderly people. Compared to Ti and Mg alloys commonly found in bone implants, Al alloys have merits such as high specific strength, excellent casting capability, and low cost, but unfortunately, the poor wear resistance, corrosion resistance, and insufficient biocompatibility have hampered wider application to bone replacements. In this study, well structure designed and excellent adhered Al₂O₃ coating is fabricated by micro-arc oxidation (MAO) on Al alloys to improve the wear resistance and corrosion resistance and inhibit release of potentially harmful Al ions from the Al alloy substrate. Ca, Fe, and Zn are respectively doped into the Al₂O₃ coating to enhance the biological properties. In particular, the Al₂O₃ coating doped with Zn delivers outstanding osteogenic performance and the antibacterial rates against E. coli and S. aureus are 99.5 ± 0.56% and 98.77 ± 0.52%, respectively. The improved mechanical and biological properties reveals that the Al₂O₃ coated Al alloys prepared by MAO coatings have large potential in orthopedic applications.