Antibacterial activity of 3D versus 2D TiO2 nanostructured surfaces to investigate curvature and orientation effects

Nanostructured surfaces have recently been established as a novel surface technology to alleviate health and industrial problems caused by bacterial biofilms. Whilst fundamental research has advanced, nanostructure arrays have generally only been developed on 2D, flat substrates, and evaluated by incubating bacteria parallel to nanostructure direction. These circumstances do not reflect real-world surfaces which are often curved and randomly oriented with respect to sedimentation direction. Titanium dioxide nanostructures on 3D, hemisphere-shaped substrates were fabricated using hydrothermal synthesis to investigate the effects of curvature and orientation on bactericidal performance. 3D surfaces were 91% more efficient at resisting Staphylococcus aureus adhesion compared to 2D surfaces, and cells that did attach were killed with the same or higher efficiency after 1 and 3 h exposure to nanostructured surfaces. This preliminary study establishes hydrothermal synthesis as a viable fabrication method of 3D bactericidal surfaces and provides insight into surface curvature and orientation impact on bactericidal efficiency.