Characteristics of multi-layer coatings synthesized on Ti6Al4V alloy by micro-arc oxidation in silver nitrate added electrolytes

•Multi-layer HA/TiO2 coatings containing Ag were synthesized by MAO method.•Silver nitrate addition in the electrolyte induced crystallization of HA layer formed on the TiO2 layer.•In vitro bioactivity was enhanced via crystallization of HA layer.•Ag nanoparticles were detected on the HA layer and provided antibacterial activity.

Multi-layer coatings (composed of outer hydroxyapatite and inner titania layers) have been synthesized on Ti6Al4V alloy for biomedical applications by employing micro-arc oxidation at positive and negative voltages of 400 and 80, respectively. Addition of silver nitrate (at concentrations of 0.1 g/L and 0.4 g/L) into the calcium acetate hydrate and disodium hydrogen phosphate anhydrous containing base electrolyte provided an enhancement in bio- and antibacterial activities of the synthesized coating, while imposing precipitation of silver nanoparticles on the hydroxyapatite layer. It is finally concluded that addition of 0.1 g/L AgNO3 into the base electrolyte is promising for MAO process of titanium-based implants, when the structural characteristics and risk of cytotoxicity are of concern for the synthesized multi-layer coatings.