| Popis: |
Healthcare-associated infection through transmission of pathogenic bacteria poses a huge threat to public health. One of the main transmission routes is via contaminated surfaces, including those of medical devices, and therefore significant efforts are being invested in developing new surface decontamination strategies. This includes visible light-based approaches, which offer improved compatibility with mammalian cells but lower germicidal efficacy with respect to UV-light. This study investigates the potential to enhance the antimicrobial efficacy of 405 nm light for surface decontamination through use of a photocatalytic TiO _2 -doped elastomer, elastomers being selected due to their wide use in biomaterials. Poly(dimethylsiloxane) (PDMS) was doped with TiO _2 nanoparticles and the surface elastomer etched to expose the embedded nanoparticles. As etching results in increased surface roughness, samples with control nanoparticles (SiO _2 and Fe _3 O _4 ) were also investigated to decouple the effects of roughness and photoinactivation upon bacterial attachment and inactivation. Characterisation by SEM, AFM and contact angle analysis confirmed that etching produced a rougher (39.3 ± 15.3 versus 5.11 ± 1.29 nm RMS roughness; etched versus unetched TiO _2 -PDMS), more hydrophobic surface (water contact angle of 120 ± 2.5° versus 110 ± 1.0°; etched TiO _2 -PDMS versus native PDMS). This surface, rich in exposed photocatalytic TiO _2 nanoparticles, allows direct contact between contaminating bacteria and nanoparticles, enabling ROS generation in closer proximity to the bacteria and consequent enhancement of visible light treatment. Incorporating TiO _2 into PDMS significantly improved the photoinactivation efficacy (mean bacterial count for light-treated samples normalised to untreated samples of 0.043 ± 0.0081) compared to PDMS alone (0.19 ± 0.036), when seeded with Staphylococcus aureus and exposed to 405 nm, 60 J cm ^−2 light. However, photoinactivation efficacy was significantly (p |
