Heat treated anodised titanium surfaces showing enhanced photocatalytic inhibition of microbial fouling

Abstract

Titanium, an otherwise perfect condenser tube material in sea water applications, is challenged by the problem of severe biofouling. Anatase, one of the two commercially important crystalline forms of titanium dioxide, possesses excellent photocatalytic activity (PCA). It has been shown in the earlier studies by the authors that anodisation of titanium produces anatase type of TiO 2 capable of photocatalytic inhibition of microbial adhesion under near UV light illumination. The present study investigates the influence of anodising voltage and anodising time on the photocatalytic inhibition of Pseudomonas sp., a frequent coloniser of natural biofilms formed on titanium surfaces. The effect of heat treatment of anodised surfaces on PCA was also studied. The results showed that heat treatment resulted in a significant enhancement of PCA. The surface oxide was characterised using glancing incidence X-ray diffraction and atomic force microscopy and the results indicate a marked increase in the cystallinity of the anatase film on the heat treated anodised surfaces. Attempts have also been made to understand the mechanism underlying the photocatalytic inactivation of the bacterial cells on TiO 2 surfaces by studying their growth characteristics.

Matrix-Assisted Laser Desorption Ionization-Time-of-Flight Mass Spectrometry As a Rapid and Reliable Technique for Directly Evaluating Bactericidal Activity: Probing the Critical Concentration of ZnO Nanoparticles As Affinity Probes

“…This is why the extent of the damage incurred to the bacterial cells is not correctly portrayed nor reflected by the plate count technique. Such an observation has been reported by Gopal et al 19 when working with TiO 2 based inhibiton of bacterial cells. They have reported a two-order difference between the total viable counts determined by the plate count method and direct acridine orange counts taken by viewing under an epifluorescence microscope.…”

Investigation of wear behavior of titanium oxide films, produced by anodic oxidation, on commercially pure titanium in vacuum conditions

“…In order to increase the thickness of the film, it is locally necessary to provide the proceeding of the process by breaking barrier film which has insulating properties. Previous investigations have shown that the properties of the titanium oxide films produced with anodization are affected by electrochemical parameters such as ion current density, solution, temperature and applied voltage [10][11][12]. Kuromota et al [13] pointed out that the morphology and thickness of anodic oxide films strongly depended on the applied voltage.…”

MALDI mass spectrometry for probing the anti- staphylococcal capability of TiO2nanoparticles via near-UV and laser irradiation

“…27 Gopal et al report the successful use of the anatase type of TiO 2 for the inactivation of bacteria using anatase TiO 2 thin films. [28][29][30][31] The mechanism of photocatalytic inhibition is that upon excitation by light whose wavelength is less than 385 nm, the photon energy generates an electron-hole pair on the TiO 2 surface. The hole in the valance band can react with H 2 O or hydroxide ions adsorbed on the surface to produce hydroxyl radicals (OH À ), and the electron in the conduction band can reduce O 2 to produce superoxide ions radicals (O À ).…”

“…report that two mechanisms seem to be operating, one through the direct oxidation by the positive holes and the other indirect oxidation by the formation of free radicals. 30,36 Direct oxidation by the positive holes results in oxidative stress within the cells which induces the formation of free radicals, which can bring about cell death. 37 Indirect oxidation involves the production of free radicals by the electron holes on the oxide surface.…”