Rhode Island’s Brown University researchers have reported that when they used selenium nanoparticles to coat polycarbonate, the material of catheters and endotracheal tubes, the results were significant reductions in cultured populations of Staphylococcus aureus bacteria, sometimes by as much as 90 percent.
Silver is widely used and considered almost the standard antimicrobial treatment material of choice for surgical implants and dressings. In contrast, Selenium is an inexpensive element that naturally belongs in the body. It is also known to combat bacteria, yet had not been tried as an antibiotic coating on a medical device material until engineers from Brown University applied it in their work on biofilm prevention.
Thomas Webster, professor of engineering and orthopaedics, is the senior author of a paper, published online this week in the Journal of Biomedical Materials Research in which a team of researchers grew selenium nanoparticles of two different size ranges and then used solutions of them to coat pieces of polycarbonate using a quick, simple process. On some of the polycarbonate, they then applied and ripped off tape not only to test the durability of the coatings but also to see how a degraded concentration of selenium would perform against bacteria.
The selenium coatings tested proved effective in reducing staph populations after 24, 48, and 72 hours compared to the uncoated controls. The most potent effects — reductions larger than 90 percent after 24 hours and as much as 85 percent after 72 hours — came from coatings of either particle size range that had not been degraded by the tape. Among those coatings that had been subjected to the tape test, the smaller nanoparticle coatings proved more effective.
The next step, Webster said, is to begin testing in animals. Such in vivo experiments, he said, will test the selenium coatings in a context where the bacteria have more available food but will also face an immune system response.
The results may ultimately have commercial relevance. Former graduate students developed a business plan for the selenium nanoparticle coatings while in school and have since licensed the technology from Brown for their company, Axena Technologies.
“We want to keep the bacteria from generating a biofilm,” said Thomas Webster, professor of engineering and orthopaedics, who studies how nanotechnology can improve medical implants.
Biofilms are notoriously tough colonies of bacteria to treat because they are often able to resist antibiotic drugs.
“The longer we can delay or inhibit completely the formation of these colonies, the more likely your immune system will clear them,” Webster said. “Putting selenium on there could buy more time to keep an endotracheal tube in a patient.”
Source: Brown University, Image credit: Webster Lab/Brown University