Hydroxyapatite/palmitic acid superhydrophobic composite coating on AZ31 magnesium alloy with both corrosion resistance and bacterial inhibition.

The coating-modified magnesium (Mg) alloys exhibit controllable corrosion resistance, but the insufficient antibacterial performance limits their clinical applications as degradable implants. Superhydrophobic coatings show excellent performance in terms of both corrosion resistance and inhibition of bacterial adhesion and growth. In this work, a hydroxyapatite (HA)/palmitic acid (PA) superhydrophobic composite coating was fabricated on the Mg alloy by the hydrothermal technique and immersion treatment. The HA/PA composite coating showed superhydrophobicity with a contact angle of 153° and a sliding angle of 2°. The coated Mg alloy exhibited excellent corrosion resistance in the simulated body fluid, with high polarization resistance (77.10 kΩ·cm²) and low corrosion current density ((0.491 ± 0.015) µA·cm⁻²). Meanwhile, the antibacterial efficiency of the composite coating was over 98% against E. coli and S. aureus in different periods. The results indicate that the construction of such superhydrophobic composite coating (HA/PA) on the Mg alloy can greatly improve the corrosion resistance of Mg alloy implants within the human body and avoid bacterial infection during the initial stages of implantation. [ABSTRACT FROM AUTHOR]