International group honours U of A researcher for nanotech silver treatment

11/16/2009

From U of A  ExpressNews
by Julia Necheff
 
(Edmonton) Sometimes two wrongs do make a right. That's the short story behind one of the most significant discoveries in wound care during the last half-century, leading to a product that has eased suffering and saved countless lives around the world.

A basic science discovery by Robert Burrell, professor and chair of the University of Alberta's Department of Biomedical Engineering, and his development of silver-based wound dressings called Acticoat, have earned him yet him another in a long string of major awards and more international acclaim.

Burrell, who holds the Canada Research Chair in Nanostructured Biomaterials, received the 2009 ASM Engineering Materials Achievement Award during a ceremony in Pittsburgh on Oct. 27. ASM International is a society for the materials science and engineering profession.

The nanocrystalline silver-coated wound dressings Burrell invented are used in more than 40 countries to prevent life-threatening infections and promote healing. Along with killing germs, their anti-inflammatory properties significantly speed healing. They are the treatment of choice in burn units, diabetic foot clinics, chronic wound clinics and nursing homes. Acticoat is the world's first therapeutic application of nanotechnology in widespread use.

As Burrell tells it, the long version of his story goes back to when he was a teaching assistant during grad school. He demonstrated the already well-known antimicrobial properties of silver to microbiology students by using old silver dimes to kill bacteria grown in petri dishes.

Years later, he was working as a researcher and wanted to show his boss the company could make antimicrobial materials by coating them in silver. So he tried to demonstrate the principle by coating some glass slides with silver and putting them in a petri dish on some bacteria. "I thought it would be a snap," he says. But the germs didn't die.

So he went to a coin shop and bought some old dimes. He ran the experiment again, this time the same way he did back in grad school, and like before, the germs died. "Why did the dimes work and the silver coatings not work? What were we showing those students back then?" he wondered to himself. He wanted to find out.

It turns out the dimes weren't just made of silver; they also contained copper. Burrell says further investigation showed the copper was reacting with the silver and oxidizing or "dissolving" at the atomic level. "So the action we thought we were showing the students wasn't the silver, it was the copper," he explains. That was the first error.

But the dissolving copper gave him an idea to try something.

He combined layers of copper and silver that were just 15 atoms thick, and put the material he fabricated into water. He predicted the copper would oxidize but that the silver, being a "noble metal," would remain intact. But it didn't remain intact because the solution contained silver ions as well as copper ions. That was his second scientific error.

But this gave him yet another idea. "It showed me that by changing its structure at the atomic level, silver could be made soluble." And if it could be made soluble, he realized it could be used in a wound dressing. In 1995, before many people were talking about nanotechnology, Burrell's team created "nanocrystalline silver." And the rest, as they say, is history.

"When we created Acticoat we created a nanostructured material. We changed the physics and chemistry of the material, and when we did that, we changed the biological activity," says Burrell, "Not only did we improve the antimicrobial activity; we gave it potent anti-inflammatory properties."

Error compounded on error led to a major advance in medicine they didn't entirely understand at the time. Burrell's increased understanding of how the materials behave came in more recent years, after he joined the University of Alberta.

He is now working on a treatment for inflammation in the lungs using a solution derived from nanocrystalline silver that is inhaled.

Robert Burrell's U of A website:
http://www.bme.med.ualberta.ca/Home/People/Academic/burrell.cfm