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July 08, 2008— Ottawa, Ontario

Canada's aging population and longer life expectancy are driving a huge demand for medical devices such as catheters, pacemakers and artificial hearts. But the patients who receive these devices are at risk for infections caused by a buildup of proteins on the device. NRC is developing coatings for medical devices that could reduce the risk of infection, leading to shorter hospital stays and fewer repeat surgeries.

Most medical devices are made of plastic, which is cheap to manufacture and can be moulded easily into almost any shape. But proteins in the body bind easily to plastic. These proteins allow bacteria to grow, leading to infections that can cause a device to fail. "Failure of an artificial heart valve would kill you," says Dr. Robert Chapman of the NRC Institute for Nutrisciences and Health in Charlottetown, P.E.I. "And the bacteria from a catheter can cause serious blood infections."

About one in 10 hospital patients acquire an infection that prolongs their stay and increases health-care costs. NRC is developing a coating for catheters and other implants that could dramatically reduce the risk of infection.
About one in 10 hospital patients acquire an infection that prolongs their stay and increases health-care costs. NRC is developing a coating for catheters and other implants that could dramatically reduce the risk of infection.

Dr. Chapman, who specializes in the interaction between synthetic materials and the human body, is looking for ways to make medical devices "invisible" to proteins. Because proteins don't bind to water molecules, he is experimenting with arrangements of molecules that have chemical properties similar to water. "If it looks like water, the protein will just keep on going," he says. Good candidates include molecular structures that include a lot of oxygen atoms or that are "water-loving," meaning they can form hydrogen bonds with water. The material must also have a neutral electric charge, since "a lot of proteins will use opposite charges to stick to a surface — it's no different than the dust sitting on your table."

Once he has a promising material, Dr. Chapman tests it with proteins such as fibrinogen, which helps blood to clot. "I try the stickiest proteins as my worst test case," he says. He then looks for ways to incorporate the material into a polymer that could coat the surface of a medical device.

Dr. Chapman hopes to begin testing new coatings within the next 18 months. Ultimately, this work could help to improve the success rates of implants and allow them to function longer in the body. The research could also lead to anti-protein coatings for tissue substitute materials, wound dressings and sensing devices used for research.

Enquiries: Media relations
National Research Council of Canada
613-991-1431
media@nrc-cnrc.gc.ca

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