Cu/SiO2 thin film on TiO2 nanotubes on Ti15Mo alloy: surface and antibacterial evaluation

In this study, the antibacterial efficacies of Cu and co-deposited Cu/SiO2 thin films with 30% and 50% Cu concentrations, as deposited on TiO2 nanotubes formed on a Ti15Mo alloy, were investigated against the Escherichia coli (E. coli) bacterium. Initially, bioactive TiO2 nanotube arrays were fabricated on the Ti15Mo alloy via anodic oxidation at 35 V and room temperature. The anodically oxidised Ti15Mo surfaces were then annealed at 400°C under atmospheric conditions to obtain a crystalline structure without any morphological difference. Well-ordered nanotube arrays with an average diameter of 80 ± 0.7 nm were obtained. To enhance antibacterial activity, ≈10-nm-thick Cu, SiO2, and Cu/SiO2 thin films were deposited on the oxidised surfaces via magnetron sputtering using a co-deposition method. The thin film deposition did not affect the surface morphology of the TiO2 nanotubes. The sputtered materials were homogeneously distributed across the entire surface and even within the nanotube interiors. All surfaces exhibited hydrophilic behaviour, with the Cu-coated surface showing the highest contact angle of 79.4°. Antibacterial testing against E. coli revealed that the Cu-coated surface exhibited a 57.9% improvement compared to bare Ti15Mo. The Cu:SiO2 (50:50) thin film demonstrated the highest antibacterial efficacy, with an 80.7% improvement.