Influence of Co-doping on Soft Spark Micro-arc Oxidation on ZrO2–AZ91D Magnesium Alloy

Magnesium (Mg) and its alloys face challenges in clinical applications due to their high degradation rates and low antibacterial properties. To overcome these challenges, this study employed an electrolyte containing elements such as F, Ca, P, Si, Sr, and Ag to perform soft spark micro-arc oxidation (MAO) on ZrO2–AZ91D Mg alloy. The research encompassed analysis of the MAO process, characterization of the composite coating's phase composition and elemental valence states, measurement of the physicochemical properties of the coating, as well as evaluation of biological properties including cell adhesion, protein adsorption, cytotoxicity, and antibacterial activity. This study investigated the mechanisms underlying osteogenesis and antibacterial effects of co-doped coatings, and examined the influence of bioactive elements on the performance of MAO coatings. The results demonstrated that the co-doped F/Ca/Sr/Ag particle-containing MAO composite coating exhibited excellent wettability and corrosion resistance. Additionally, the coating displayed remarkable protein adsorption capacity, superior adhesion to MC3T3-E1 osteoblast cells, and excellent antibacterial efficacy against Staphylococcus aureus, all while showing negligible toxicity.