Gas-Phase Produced Cu@CuO Nanoparticles on Microarc Oxidized TiO₂: Effect of Size on Antibacterial Efficiency and Osteoblast Viability

In this work, highly porous and rough TiO 2 surfaces coated with Cu@CuO core–shell nanoparticles were fabricated on a Ti6Al4V alloy by microarc oxidation (MAO) and gas-phase synthesis. The phase structure, binding energy, surface morphology, elemental distribution, and wettability were investigated by XRD, XPS, SEM, EDX-mapping, and contact angle goniometery, respectively. Cu@CuO core–shell nanoparticles with mean particle sizes of 8.1 ± 0.2, 15.2 ± 0.3, and 17.2 ± 0.2 nm were deposited onto anatase- and rutile-based MAO surfaces. Cu, Ti, and O were all found to be homogeneously distributed across the entire sample surface. MAO surfaces decorated with Cu@CuO nanoparticles exhibited hydrophobic behavior compared to bare Ti6Al4 V and bare MAO surfaces, leading to the demonstration of antimicrobial activity. For Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa, and Escherichia coli, the antimicrobial activity of the Cu@CuO-nanoparticle-treated MAO surfaces was significantly improved with respect to a bare substrate and bare MAO surfaces. In addition, cell viability increased proportionally with increasing Cu@CuO nanoparticle size compared to the MAO surface.