Stability and prospect of UV/H2O2 activated titania films for biomedical use

Abstract

Biomedical implants and devices that penetrate soft tissue are highly susceptible to infection, but also accessible for UV induced decontamination through photocatalysis if coated with suitable surfaces. As an on-demand antibacterial strategy, photocatalytic surfaces should be able to maintain their antibacterial properties over repeated activation. This study evaluates the surface properties and photocatalytic performance of titania films obtained by H 2 O 2 -oxidation and heat treatment of Ti and Ti-6Al-4V substrates, as well as the prospect of assisting photocatalytic reactions with H 2 O 2 for improved efficiency. H 2 O 2 -oxidation generated a nanoporous coating, and subsequent heat treatment above 500°C resulted in anatase formation. Tests using photo-assisted degradation of rhodamine B showed that prior to heat treatment, an initially high photocatalytic activity (PCA) of H 2 O 2 -oxidized substrates decayed significantly with repeated testing. Heat treating the samples at 600°C resulted in stable yet lower PCA. Addition of 3% H 2 O 2 during the photo-assisted reaction led to a substantial increase in PCA due to synergetic effects at the surface and H 2 O 2 photolysis, the effect being most notable for non-heat treated samples. Both heat treated and non-heat treated samples showed stable PCA through repeated tests with H 2 O 2 -assisted photocatalysis, indicating that the combination of H 2 O 2 -oxidized titania films, UV light and added H 2 O 2 can improve efficiency of these photocatalytic surfaces. Highlights Ti and Ti64 substrates were surface modified by H 2 O 2 -oxidation and heat treatments. TiO 2 /UV/H 2 O 2 synergy effects significantly boosted rhodamine B degradation. 3% H 2 O 2 addition increased stability over repeated use.

Synergetic inactivation of <i>Staphylococcus epidermidis</i> and <i>Streptococcus mutans</i>in a TiO2/H2O2/UV system

“…45 A gradual decline in activity, which indicates the release and effect of surface bound peroxides from H 2 O 2 -oxidized Ti-based substrates, accelerated under UV irradiation, was reported in a previous study. 46 Interestingly, the same study showed that addition of 3% H 2 O 2 during the reaction was sufficient to maintain a high photocatalytic activity through 6 and 1.28 × 10 6 CFU/mL for S. epidermidis and S. mutans, respectively. Asterisk (*) indicates significant difference from the ti DCt, and double asterisk (**) indicates significant difference from both ti and tio 2 DCts, both at P < 0.05.…”

“…Additionally, the H 2 O 2 -oxidation technique employed in this study is known to increase surface roughness and surface area of the substrate, and consequently also photocatalytic activity. 16 Although demonstrated to generate a relatively homogeneous surface, 16,46 some irregularities that shelter or expose bacteria may still exist, which could account for some variability in the data. It is also recognized that UV exposure has certain bactericidal effects in its own, and that such effects could be enhanced in the current model due to an increase in temperature and accelerated drying.…”

Reactive combinatorial synthesis and characterization of a gradient Ag–Ti oxide thin film with antibacterial properties

“…Further, sputtering at room temperature and avoiding any subsequent crystallization heat treatment conserved the amorphous structure and any meta-stable phases. Heat treatment of the sample would likely induce crystallization and anatase or further rutile formation of available TiO 2 , with potential enhancement of photocatalytic properties along the gradient as a result [45]. However, raising the temperature above 75°C has been reported to result in considerable densification, crystallite growth and decomposition of Ag 2 O in nanocrystalline silver films, impeding antibacterial properties [46].…”

A superhydrophilic titanium implant functionalized by ozone gas modulates bone marrow cell and macrophage responses

“…These methods are shown to be effective in increasing osteoconductivity of titanium implant. However, among those, only limited methods are available to modify titanium implant with complex shapes such as screws, porous structures, sheets and hollow cylinders [20][21][22]. For example, UV-photofunctionalized titanium recently has been attracted much attention due to excellent osteoconductivity, simplicity, and cost-effectiveness [16].…”