Metal oxide-doped elastomeric materials for enhancement of 405-nm light-based antimicrobial surface decontamination

The rapid rate at which microbes are evolving to resist current antimicrobial treatments poses a huge threat to public health, therefore novel decontamination methods are urgently required to prevent their spread and proliferation.
This study investigates the use of titanium dioxide (TiO₂)-elastomer composites to enhance the antimicrobial efficacy of 405-nm visible light for surface decontamination. Photocatalytic TiO₂ nanoparticle-doped polymers were prepared and the surface of the cured elastomer (poly(dimethylsiloxane)) wet etched to expose embedded nanoparticles. Surface characterisation by SEM and contact angle analysis confirmed that etching exposed the surface nanoparticles producing a rougher and more hydrophobic surface. By creating a surface rich in exposed photocatalytic nanoparticles, contaminating bacteria could be in direct contact with the TiO₂ nanoparticles and there is the potential for ROS generation in closer proximity to the bacteria, and therefore greater enhancement of the 405-nm light treatment.
Metal-oxide samples were seeded with Staphylococcus aureus and exposed to antimicrobial 405-nm light (60 J/cm²), and the bacterial inactivation quantified. Results demonstrated that incorporation of the TiO₂ nanoparticles into the polymer improved the surface decontamination efficacy compared to on the polymer alone (1.4-log₁₀ reduction compared to 0.7-log₁₀). Surface decontamination efficacy was further enhanced by the etching of the photocatalytic TiO₂ polymer surfaces, resulting in a 1.9-log₁₀ reduction following light treatment.
Overall, results demonstrate that incorporation of TiO₂ nanoparticles and surface etching can significantly enhance the antibacterial efficacy of 405-nm light for surface decontamination, highlighting the potential for this mechanism to be developed for TiO₂-doped medical devices and surfaces.