Light-activated materials that kill pathogens on their surface have been created in the past – but once the light goes out, they lose their potency. That’s one of the reasons we’ve yet to see such active materials coating the surfaces of hospital furniture and equipment. Now a new material has been developed at University College London that features multiple anti-microbial mechanisms that work in both darkness and light.
The material relies on a combination of light reactive dyes and gold nanoparticles, applied to a substrate of silicone. The silicone swell up, using a solvent and added to a methylene blue / gold nanoparticle solution. The solution permeated the silicone and diffused throughout. A dye layer was then added to the surface by dipping the resulting silicone in crystal violet. The resulting material showed “the most potent bactericidal effect ever observed in such a surface,” according to UCL and the silicone remained hydrophobic and didn’t seem to change much its other useful properties.
“Despite contaminating the surface with far more bacteria than you would ever see in a hospital setting, placed under a normal fluorescent light bulb, the entire sample was dead in three to six hours, depending on the type of bacteria,” said the paper’s lead author, Sacha Noimark, in a UCL release. “That was an excellent result, but the bigger surprise was the sample which we left in the dark. That sample too showed significant reductions in bacterial load, albeit over longer timescales of about three to eighteen hours. The precise mechanism by which this dark-kill works is not yet clear, though.”
Study in journal Chemical Science: Light-activated antimicrobial surfaces with enhanced efficacy induced by a dark-activated mechanism
University College London: Scientists develop world’s first light-activated antimicrobial surface that also works in the dark