Antibacterial HA-coatings on bioresorbable Mg alloy

Abstract

In this study, a calcium-phosphate coating was formed on a Mg–Mn–Ce alloy by the plasma electrolytic oxidation (PEO). The antibiotic vancomycin, widely used in the treatment of infections caused by Staphylococcus aureus (S. aureus), was impregnated into the coating. Samples with vancomycin showed high bactericidal activity against S. aureus. The mechanical and electrochemical properties of the formed coatings were studied, as well as in vitro cytotoxicity tests and in vivo tests on mature male rats were performed. According to SEM, EDS, XRD and XPS data, coatings had a developed morphology and contained hydroxyapatite, which indicates high biocompatibility. The analysis of roughness of coatings without and with vancomycin did not reveal any differences, confirming the high roughness of the samples. During electrochemical tests, an increase in corrosion resistance by more than two times after the application of PEO coatings was revealed. According to the results of an in vivo study, after 28 days of the implantation of samples with calcium phosphate PEO coating and vancomycin, no signs of inflammation were observed, while an inflammatory reaction developed in the area of implantation of bare alloy, followed by encapsulation. Antibiotic release tests from the coatings show a sharp decrease in the concentration of the released antibiotic on day 7 and then a gradual decrease until day 28. Throughout the experiment, no significant deviations in the condition and behavior of the animals were observed; clinical tests did not reveal a systemic toxic reaction.

Keywords

• Bioactive coatings
• Biocompatibility
• Mg alloy
• Plasma electrolytic oxidation
• Hydroxyapatite
• Vancomycin