More human-friendly antibacterial coating made from gold

Research team member Dr. Katarzyna Wybranska, with a wound dressing treated with the gold nanocomposite (Photo: ICHF)

We've been hearing a lot about the antibacterial qualities of silver, with silver nanoparticles finding use in everything from water filters to food packaging. Unfortunately, there are also concerns about the toxicity of those particles, particularly when they enter our bodies. Now, however, Polish scientists have developed what they claim is a safer alternative – an antibacterial coating that kills microbes using gold.

Developed at the Institute of Physical Chemistry of the Polish Academy of Sciences in Warsaw, the coating can reportedly be applied to a wide variety of surfaces. It's said to be very chemically stable, and is able to withstand repeated washings with detergent.

The coating initially takes the form of liquid boron compounds which contain colloidal gold nanoparticles. The object to be coated is immersed in the solution, and a polymerizing agent is then added. This causes the liquid to form into a nanocomposite polymer, coating the surface of the object within about 12 minutes.

In lab tests, populations of E. coli and Staph. aureus bacteria decreased by up to 90 percent within 12 hours of exposure to the nanocomposite. Unlike some other antibacterial coatings, however, this one doesn't kill bacteria by releasing anything into their environment. Instead, the gold nanoparticles stay put, and only affect microbes that come into direct contact with them. Not only is this quality claimed to make the coating safer for people and the environment, but it should also allow it to remain effective for longer.

Additionally, the nanocomposite so far appears to be harmless to human cells. After being exposed to it for several months, four lines of human cells reportedly remained unharmed. In fact, cells even started growing on cotton wool fibers treated with it.

It is hoped that once developed further, the coating could be used on things like wound dressings and other medical applications, along with consumer goods such as sportswear, socks and underwear.

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