Structural and surface properties of semitransparent and antibacterial (Cu,Ti,Nb)Ox coating

•Structural and surface properties of bioactive (Cu,Ti,Nb)Ox thin films were examined.•Semitransparent thin films were prepared by magnetron sputtering.•Hardness of the thin film was examined.•Surface topography had an impact on wettability.•Antibacterial effect related to CuO form in the film. In this work structural and surface properties of oxide thin-film coating based on Cu, Ti and Nb prepared by reactive magnetron sputtering have been described. During the deposition process metallic Cu, Ti and Nb targets were sputtered in oxygen plasma. Structural characterization of the film microstructure has revealed that as-prepared coating was amorphous. Due to such structure and the content of Ti and Nb the hardness of the oxide film was about 3.6GPa, which is 40% higher as compared to metallic Cu film. Moreover, the surface roughness was below 1nm, what resulted in receiving of hydrophobic properties. The multioxide film was transparent at the level of 40%, but due to high Cu-content its optical absorption edge was about 450nm and had bright orange color. Optical investigation has revealed that the energy band-gap of this film was 1.41eV, which indicates on the presence of CuO form. Moreover, the studies of antimicrobial activity showed that as-prepared film had a strong bactericidal effect for Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Bacillus subtilis and Enterococcus hirae, while fungicidal effect for Candida albicans was not observed. The biological activity was related to the amount of copper ions released from the surface of (Cu,Ti Nb)Ox coating, which was equal to 0.041ppm per day.