In Vitro Degradation Behavior, Cytotoxicity and Antibacterial Properties of Biomedical Mg-Cu Alloy Implant Materials with Different Coatings

Biodegradable Mg-Cu alloys possess excellent antibacterial property. However, their rapid degradation rate limits their wide range of application in the field of orthopedic trauma. In this work, micro-arc oxidation (MAO) coating, chemical conversion Sr-P coating and chemical deposition Ca-P coating were fabricated on Mg-0.2Cu alloy. Microstructural characterization, immersion test, electrochemical experiment, cytotoxicity analysis and antibacterial test were then carried out. The results showed that the MAO-coated samples exhibited the best corrosion resistance, with a degradation rate of 0.29 μA/cm² in Hank’s solution calculated after the electrochemical test. Meanwhile, the Sr-P- and Ca-P-coated samples displayed higher cell viabilities compared to the MAO coating due to the release of nutritious elements such as Sr, Ca and P. The antibacterial rates of the three coatings co-cultured with staphylococcus aureus (S. aureus) reached values ranging between 90 and 99%, within 12 h and 24 h, respectively. Moreover, the MAO coating showed excellent antibacterial activity at the initial co-culture stage (6 h), with the antibacterial rate surpassing 95%. Consequently, the MAO-coated Mg-0.2Cu alloy has great potential to be used as biodegradable implants with good corrosion resistance and impressive antibacterial performance.