Visible-light-responsive antibacterial activity of Au-incorporated TiO2 layers formed on Ti-(0-10)at%Au alloys by air oxidation.

ABSTRACT

Rutile TiO2 layers were formed on substrates of Ti-(0-10)at%Au alloys by a simple process of air oxidation, and their antibacterial activities were evaluated under visible-light irradiation (λ ≥ 400 nm). Au was introduced into the TiO2 layers on Ti-(1-10)at%Au alloys and existed as both metallic Au nanoparticles and dissolved Au3+ ions. The TiO2 layers that formed on Ti-5at%Au and Ti-10at%Au alloys exhibited visible-light photocatalytic activity, that is, degradation of stearic acid and antibacterial activity against Escherichia coli. These visible-light activities were attributed to the surface plasmon resonance of metallic Au nanoparticles and the decrease in bandgap energy caused by dissolved Au3+ ions. The formation of hydroxyl radicals observed under visible-light irradiation is attributable to antibacterial activity. From a cost perspective, a Ti-5at%Au alloy is more suitable as a substrate for the formation of a TiO2 layer with antibacterial properties than a Ti-10at%Au alloy. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A 107A 991-1000, 2019.