Brown University engineers have discovered that when selenium nanoparticles coat a polycarbonate, a material common in medical devices, it is very effective in preventing the accumulation of bacteria, particularly the dangerous Staphylococcus aureus.
It is widely known that selenium is an inexpensive element that occurs naturally in the human body. And it is also known that it combats bacteria. However, it has not been tried as an antibiotic coating on a medical device material, reports Futurity.org. In their research, the engineers treated polycarbonate used in catheters and endotracheal tubes.
“We want to keep the bacteria from generating a biofilm,” says Thomas Webster, Brown professor of engineering and orthopedics, who studies how nanotechnology can improve medical implants. He is the senior author of the paper describing the research, published in the Journal of Biomedical Materials Research, Part A.
Biofilms are tough colonies of bacteria to eradicate because they often 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 says. “Putting selenium on there could buy more time to keep an endotracheal tube in a patient.”
Because selenium is a recommended nutrient, it should be harmless in the body in concentrations found in the coatings, Webster says. A benefit of selenium is that it is less expensive than silver, another element, but a less biocompatible one that is the current state-of-the-art material used for antibacterial coatings.
The engineers developed four different types of selenium coatings, and all proved effective in reducing Staph populations after 24, 48, and 72 hours compared to uncoated control samples. Staph populations exposed to any of the coated polycarbonate samples peaked at 48 hours, most likely because that is when the bacteria took the fullest advantage of the in vitro culture. However, those population levels fell back significantly by the 72-hour point.
The team wants to test in animals next. As in in vitro experiments, the selenium coatings in these tests will have nutrients from which to feed, but they will also face an immune system response.
Further research with positive results can have commercial relevance. Former graduate studets at Brown who worked on the project developed a business plan for the nanoparticle coatings and have since licensed the technology from Brown for their company, Axena Technologies.
Source: “Selenium Keeps Staph Bacteria Off Implants,” Futurity.org, 6/21/12
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Dale McGeehon has been a journalist and editor for more than 25 years, covering chemical regulation and testing for Pesticides and Toxic Chemical News and innovations in material sciences for the National Technology Transfer Center. His writing credits include Omni and College Park magazines and The New York Times.