Antimicrobial activity of polyurethane embedded with methylene blue, toluidene blue and gold nanoparticles against Staphylococcus aureus; illuminated with white light

Polyurethane polymer sheets were embedded with methylene blue (MB), toluidine blue (TBO) and 2 nm gold nanoparticles by a swell–shrink encapsulation process using an acetone water mixture. The polymers were characterised by IR, UV–vis, SEM/WDX and mechanical testing. The dye impregnated polymers were potent at killing suspensions of Staphylococcus aureus under white illumination with a hospital light source (2000 lux) showing a 2.8 log10 kill (MB) and a 4.3 log10 kill (TBO) compared to controls when exposed to 24 h of illumination. Notably the incorporation of gold nanoparticles with the dyes enhanced the observed kill to 3.8 log10 (MB) and 4.8 log10 (TBO). This is the first time that a derivatised polyurethane polymer used in catheters has been shown to be effective in killing bacteria using white light illumination.