Highly
reactive oxygen radicals destroy the cell walls of bacteria.
Hospital-acquired
infections are a major health threat, and have prompted the development of
preventative measures incorporating things like blue light and
selenium
nanoparticles. One of the latest such developments is a
light-activated antimicrobial surface coating made from silicone, dye and gold.
For some reason, it also works in the absence of light.
Created at
University College London, the coating incorporates crystal violet and
methylene blue dyes, along with gold nanoparticles. When the dyes are exposed
to light, the electrons in them become excited. This in turn results in the
production of "highly reactive oxygen radicals," which destroy the
cell walls of bacteria.
To make the
material, an organic solvent was used to swell the silicone, which allowed the
methylene blue and gold to diffuse throughout it. The dye- and gold-infused
silicone was then dipped in a bath of crystal violet, causing a layer of that
dye to bond to its surface.
In lab
tests, the coating was shown to have "the most potent bactericidal effect
ever observed in such a surface" when exposed even just to a regular
fluorescent light bulb, killing all the bacteria placed upon it within three to
six hours.
What was
surprising, however, was that it also killed microbes when contaminated with
them and left in the dark – it just took longer, up to 18 hours. It's
reportedly the first time that a light-activated antibacterial substance has
shown such good no-light performance. Exactly how it was able to do so is still
being investigated.
Additionally,
the coating is said to be relatively inexpensive to manufacture, and resists
being worn off of surfaces when they're being cleaned. It could end up being
used on items ranging from medical equipment to a hospital's door handles,
keyboards or other frequently-touched objects.
Source: University College London