UV light, coatings reduce bacterial adhesion up to 50 percent

08/23/04

The combination of ultraviolet (UV) light and certain coatings can lower -- by 15 to 50 percent -- the ability of some types of bacteria to stick to a glass surface and cause contamination or biofouling, Penn State environmental engineers have found.

Dr. Baikun Li, assistant professor of environmental engineering, Penn State Harrisburg, says "Ultraviolet light has been used for many years as an environmentally friendly route to water disinfection. However, these new results indicate that ultraviolet light, combined with certain coatings, also may offer a 'green' approach to keeping glass surfaces free of contamination."

Li described her results in a paper, "The Impact of Ultraviolet Light on Bacterial Adhesion to Glass and Metal-Oxide Coated Surfaces," at the American Chemical Society meeting, Sunday, Aug. 22, in Philadelphia. Her co-author is Dr. Bruce Logan, the Kappe professor of environmental engineering, Penn State's University Park campus.

The Penn State researcher exposed flat glass surfaces (silica dioxide) coated with thin layers of silicon dioxide, titanium dioxide or tin dioxide to eight different strains of bacteria, including some disease-causing types, and two different wavelengths of UV light. Measurements showed that the lower wavelength UVC light (254 nm) lowered cell adhesion by 15 to 50 percent, depending on the type of bacteria, on both the titanium dioxide and tin dioxide coated surfaces. The higher wavelength UVA light (340nm) produced similar effects for glass coated with titanium dioxide but not with tin dioxide. Higher intensity light reduced adhesion more than lower intensity UV light.

Li says, "Our work is among the first studies of the combination of ultraviolet light and coatings to prevent biofouling. These early results are promising and suggest potential for further study and anti-biofouling application."

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