Fabrication of a visible-light-responsive photocatalytic antibacterial coating on titanium through anodic oxidation in a nitrate/ethylene glycol electrolyte

Abstract

To provide semi-permanent antibacterial function for titanium medical implements, such as micro-tweezers, hemostatic forceps, and needle holders, a visible-light responsive nitrogen-doped titanium dioxide (TiO2) layer that strongly adheres to Ti materials was fabricated through anodization in an electrolyte comprising ammonium nitrate in ethylene glycol, followed by heating at 723K in air. The predominant structure of the oxide layer was TiO2 with a rutile structure that contained ca. 1at.% of incorporated nitrogen. The outward appearance of the oxide layer was quite smooth, and the topographic microstructure was a flat surface that included small pores. The thickness of the surface layer was approximately 10μm, and the layer strongly adhered to Ti substrates. This fabricated anodic layer acted as a photocatalyst both under UV-light and visible-light illumination, and showed excellent antibacterial performance under both types of illumination. Anodic oxidation in a nitrate/ethylene glycol electrolyte is an innovative surface modification technique that can be used to simply form visible-light responsive photocatalytic antibacterial coatings on biomedical Ti materials.