Photocatalytic anti-bioadhesion and bacterial deactivation on nanostructured iron oxide films

Bacterial adhesion and biofilm formation on metals are a primary mechanism causing integrity degradation and failure of engineering structures. Conventional anti-bioadhesion methods usually impact the sustainability of environments and ecosystems. In this work, nanostructured iron oxide films were fabricated by electrochemical anodization of steel in a concentrated alkaline solution. The morphology, surface roughness, composition and photoelectrochemical properties of the nano-films were characterized, and the anti-adhesion properties of the films to Pseudomonas aeruginosa bacteria were investigated. A photoelectrochemical based model was developed to explain mechanistically the photocatalytic anti-bioadhesion and bacterial deactivation of the iron oxide nano-films. Results demonstrate that the nanostructured iron oxide films enable effective anti-adhesion of the bacteria to the filmed steel. The photocatalytic activity of the nano-films further deactivates the bacteria remaining on the specimen surface under visible light illumination. In particular, the nano-film formed by 10 min of anodization features the largest surface roughness, the highest photocatalytic activity, and the best performance for anti-bioadhesion and bacterial deactivation. Compared to bare steel, a 99.9% anti-bioadhesion performance is achieved. The nanostructured iron oxide films can deactivate the bacteria remaining on the film surface due to oxidative holes and reactive oxygen species generated during photo illumination.