Home Uncategorized New slippery silicone keeps bacteria off medical equipment

New slippery silicone keeps bacteria off medical equipment

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Scientists in the US have invented a new material that makes urinary
catheters, intravenous catheters, and implants so slippery,
life-threatening colonies of E. coli and Staph bacteria struggle to accumulate on them.

It’s
estimated that biofilms – adhesive colonies of harmful bacteria that
form on medical equipment – are responsible for more than 80 percent of all microbial infections in the body,
and there are a select few species of bacteria that are becoming
increasingly difficult to deal with in hospitals, even with copious
amounts of antibiotics on hand.
For example, urinary tract infections (UTIs) represent 40 percent of all hospital-acquired infections, and 11 percent of those are caused by the bacterium Pseudomonas aeruginosa. In fact, P. aeruginosa currently accounts for up to 15 percent
of all hospital-acquired infections in the US, and it’s notoriously
resistant to the drugs we try to combat it with. 
Two of the most
significant human pathogens, E. coli and Staphylococcus epidermidis, are
similarly troublesome, causing all kinds of tissue and blood infections
thanks to their continued and widespread existence in even the world’s
cleanest and best-staffed hospital environments. If you’re really
unlucky, you could go in for a routine surgical procedure, and die from a
severe bacterial infection.
Long story short, we need better ways
of keeping our medical equipment free from bacteria, and antibiotic
treatments are becoming less and less of an option.
So a team led
by chemist Joanna Aizenberg from the Kavli Institute for Bionano Science
and Technology at Harvard University has come up with a solution:
commercially available silicone tubing – the same kind that’s already
being used in today’s medical tubing – infused with high-purity silicone
oil. This silicone mixture releases a self-lubricating, slippery
coating that’s super-repellent, long-lasting, non-toxic, and cheap to
produce.
Suitable for all kinds of medical surfaces, including
those of mechanical heart valves, urinary catheters, intravenous
catheters, and implants, this silicone material has been engineered to
take up and store large amounts of lubricating silicone oil in its
molecule structure, just like a sponge. This means where ever it’s used,
the substance will form a smooth lubricant layer over the surface,
making it a whole lot more difficult for bacteria to hold on to and
colonise the area.

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“The solid silicone tubing is saturated with
silicone oil, soaking it up into all of the tiny spaces in its molecular
structure so that the two materials really become completely integrated
into one,” one of the team, Caitlin Howell said.
And
the best part is it doesn’t lose its slipperiness over time, because
the silicone oil is only released onto the surface of the silicone when
needed, so to replace any oil that’s been wiped away by other liquids
such as urine, blood, or gastro-intestinal fluids.
To test their new coating, the team exposed treated and untreated medical tubing to P. aeruginosa, E.coli, and Staphylococcus epidermidis. They found that the silicone oil-infused tubing greatly reduced bacterial adhesion and largely eliminated biofilm formation.
The researchers discuss their results in the journal ACS Biomaterials Science & Engineering:

“We
have demonstrated that P. aeruginosa biofilm formation can be reduced
in various shear conditions, including those representative of
indwelling catheters, by at least 10-fold. After a five-second wash with
water, the biofilm volume can be almost completely removed, while a
robust biofilm remained on the untreated control silicone surfaces.
Further, the materials passively resist bacterial accumulation without
the use of bactericidal agents, and could thus be developed as an
important component in reducing excessive antibiotic usage.”

“With
widespread antibiotic resistance cropping up in many strains of
infection-causing bacteria, developing out-of-the-box strategies to
protect patients from bacterial biofilms has become a critical focus
area for clinical researchers,” added one of the team, bioengineer
Donald Ingber, in the press release.
“Liquid-infused polymers could be used to prevent biofilms from ever
taking hold, potentially reducing rates of infection and therefore
reducing dependence on antibiotic use.
The next step is to get FDA approval
so the new material can be used in hospitals. As the silicone parts
have already been approved, this will hopefully only take a couple of
years. The team is also now working on expanding the technology to other
applications, such as keeping the surfaces of waste-water management
systems, maritime vessels, and oil pipes clean. 
“Each technology
in our portfolio has different properties and potential uses, but
collectively this range of approaches to surface coatings can prevent a
broad range of life-threatening problems,” says Aizenberg, “from ice accumulation on airplane wings to bacterial infections in the human body.”

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