Characterization and antibacterial activity of co-sputtered Cu-doped TiO₂ coatings deposited on Ti6Al4V alloy

Abstract

Copper has gained increased interest because of its important role in metabolism and antimicrobial activity. In this study, composite target material of Ti and Cu was used to deposit TiO2 coatings doped with copper on Ti6Al4V alloy. The aim was to examine the influence of the applied bias during the deposition of Cu-doped TiO2 coating by sputtering in a glow-discharge in a pure O2 atmosphere for a deposition time of 240 min. Different substrate values, selected from 0 to -150 V, were used in the process. The increase in bias voltage from -50 to - 150 V decreased the thickness of the oxide coatings and improved their adhesion to the substrate while increasing the Cu2O phase at the expense of a CuO phase decrease. Simultaneously, the increase in bias voltage decreased Cu content from about 32 wt% for the -50 V biased down to around 11 wt% for the -150 V biased specimens. The antimicrobial efficacy against E. coli estimated by direct contact experiments on the top of the uncoated (control) and coated Ti6Al4V alloy revealed about 94% inhibition for the -50V biased down to around 37% for the -150 V biased coatings as opposed to the control.