To stop the spread of
disease, it could be used to coat phone screens and keyboards, as well as the
inside of catheters and breathing tubes, which are a major source of
healthcare-associated infections (HCAIs).
The research is the
first to show a light activated antimicrobial coating successfully killing
bacteria in low intensity, ambient light (300 Lux), such as that found in wards
and waiting rooms. Previously, similar coatings needed intense light (3,000
Lux), like that found in operating theatres, to activate their killing
properties.
The new bactericidal coating is made of tiny clusters of chemically modified
gold embedded in a polymer with crystal violet -- a dye with antibacterial and
antifungal properties.
First author, Dr Gi
Byoung Hwang (UCL Chemistry), said: "Dyes such as crystal violet are
promising candidates for killing bacteria and keeping surfaces sterile as they
are widely used to disinfect wounds. When exposed to bright light, they create
reactive oxygen species, which in turn kill bacteria by damaging their
protective membranes and DNA. This is amplified when they are paired with
metals such as silver, gold and zinc oxide."
The team of chemists,
chemical engineers and microbiologists created the bactericidal coating using a
scalable method and tested how well it killed S. aureus and E. coli against
control coatings and under different lighting conditions.
Sample surfaces were
treated with either the bactericidal coating or a control coating before being
inoculated with 100,000 colony forming units (CFU) per ml of either S. aureus
and E. coli. The growth of the bacteria was investigated under dark and white
light conditions between 200 -- 429 Lux.
They found that in
ambient light, a control coating of crystal violet in a polymer alone did not
kill either bacteria. However, in the same lighting conditions, the
bactericidal coating led to a 3.3 log reduction in the growth of S. aureus
after six hours and a 2.8 log reduction in the growth of E. coli after 24
hours.
See:
Posted by Dr. Tim Sandle, Pharmaceutical Microbiology Resources (http://www.pharmamicroresources.com/)
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