Stability and prospect of UV/H_2O_2 activated titania films for biomedical use

摘要

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_2O_2-oxidation and heat treatment of Ti and Ti-6Al-4V substrates, as well as the prospect of assisting photocatalytic reactions with H_2O_2 for improved efficiency. H_2O_2-oxidation generated a nanoporous coating, and subsequent heat treatment above 500 ℃ 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_2O_2-oxidized substrates decayed significantly with repeated testing. Heat treating the samples at 600 ℃ resulted in stable yet lower PCA. Addition of 3% H_2O_2 during the photo-assisted reaction led to a substantial increase in PCA due to synergetic effects at the surface and H_2O_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_2O_2-assisted photocatalysis, indicating that the combination of H_2O_2-oxidized titania films, UV light and added H_2O_2 can improve efficiency of these photocatalytic surfaces.