Microstructural evolution and biological performance of Cu-incorporated TiO2 coating fabricated through one-step micro-arc oxidation

Abstract In the present work, a Cu-incorporated TiO2 coating was successfully fabricated through a one-step micro-arc oxidation (MAO) of Ti in a solution containing 10 g/L ethylene diamine tetraacetic acid cupric disodium (Na2Cu-EDTA). Interestingly, different colour appearances of the resultant Cu-incorporated TiO2 coating were noticed with the presence of black area at the edge and brown area in the centre. Further, microstructural characterization reveals that, unlike the central brown area with high amount of Cu+, the peripheral black area is mainly enriched in Cu2+, which exhibits a two-layered structure consisting of TiO2 inner layer and porous Ca, P-rich outer layer containing nano-sized hydroxyapatite (HA) crystals. Finally, biological examination reveals that the peripheral black area exhibits both improved bone formability and enhanced antibacterial capability in comparison to the central brown area. Based on the observation, the coating formation mechanism is proposed, which provides valuable guidance for the utilization of MAO method in the field of bio-medical materials.