Improvements of Corrosion Resistance and Antibacterial Properties of Hydroxyapatite/Cupric Oxide Doped Titania Composite Coatings on Degradable Magnesium Alloys.

Abstract

The excellent biocompatibility of calcium phosphate (CaP) coatings makes them widely used in magnesium (Mg) alloy orthopedic implant materials. However, the porous morphology of CaP coatings limits their corrosion resistance. A cupric oxide (CuO) doped titania (TiO2) sol-gel coating is prepared on a porous hydroxyapatite (HA) coating. According to electrochemical test results, the HA/CuO-TiO2 coating obtains a current density of 6 × 10-4 mA/cm2, lower than that of the Mg alloy (2.6 × 10-2 mA/cm2). The hydrogen evaluation of the HA/CuO-TiO2 coating is only 1/12 that of the Mg alloy after immersion for 7 days. In addition, the HA/CuO-TiO2 coating has an antibacterial rate of 99.5 ± 0.4% against Staphylococcus aureus, significantly higher than that of the HA coating (19.8 ± 0.3%) and HTC0 coating (38.4 ± 0.5%). The CuO doped composite coating has no adverse effect or cytotoxicity on cell proliferation (cell viability ≥79.6%). Hence, the HA/CuO-TiO2 composite coating is useful for enhancing the corrosion resistance and antibacterial properties of Mg alloys while ensuring cytocompatibility. The HA/CuO-TiO2 coated AZ60 Mg alloy can meet the requirements of clinical application.