Improving corrosion, antibacterial and biocompatibility properties of MAO-coated AZ31 magnesium alloy by Cu(II)-chitosan/PVA nanofibers post-treatment

Abstract

In this study, a novel Cu(II)-Chitosan/PVA electrospun coating containing different concentrations of Cu(II) was applied to AZ31 magnesium alloy samples, pre-treated with the MAO (micro-arc oxidation) method, in order to enhance its antibacterial activity, cell viability, and corrosion resistance for orthopedic applications. Structure and morphology, water absorption and wettability, Cu(II) ion release, antibacterial activities, and cell biology were all studied in these coatings. Electrochemical impedance spectroscopy (EIS) was used to determine the corrosion resistance of the coatings. SEM images showed that all fibers of electrospun samples exhibited crack-free, unbeaded, and uniform fibrous structures with an average diameter range of about 220–340 nm. The corrosion resistance of the MAO pretreatment enhanced cell viability, and the unique structure of the electrospun layer promoted cell attachment and proliferation to the coating. The coatings demonstrated satisfactory antibacterial activity against both gram-positive and gram-negative bacteria. Furthermore, coatings with higher Cu(II) concentrations released more Cu(II) ions, resulting in improved antibacterial properties. However, despite the reduced cell viability for the coatings containing 8.42% Cu(II), the cell viability of the coatings with 0.77% and 2.97% Cu(II) was not significantly affected, and they were not harmful to MG63 cells, but high concentrations of Cu(II) ions caused significant cytotoxicity.