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A paper about the germ-killing potential of cold plasmas authored by Mounir Laroussi of the Old Dominion University engineering faculty has been selected by the New Journal of Physics (NJP) as one of the most significant articles it published during the last decade.

The paper, "Plasma Interaction with Microbes," which was published in 2003, will be included in a special collection of article summaries commemorating the 10th anniversary of the journal in 2008. NJP debuted in 1998 as a publication of the Institute of Physics and the Deutsche Physikalische Gesellschaft.

In this paper, Laroussi and his co-authors demonstrated a correlation between electrostatic forces caused by charging effects in a plasma and experimentally observed morphological changes in bacterial cells. After its publication, this paper became one of the most downloaded papers and was added to the "select" list of the Institute of Physics.

Laroussi, ODU associate professor of electrical and computer engineering and director of the university's Laser and Plasma Engineering Institute (LPEI), has been a pioneering researcher in cold plasmas and in biological applications of plasmas. The plasma pencil, a hand-held device like a miniature light-saber that Laroussi introduced in 2005, was the subject of news reports in National Geographic and numerous other publications around the world.

The plasma pencil generates a thin plume of charged gas that can kill certain cells and bacteria. Researchers hope that cold plasmas will have applications ranging from killing the bacteria that cause dental plaque to eradicating tumors.

Plume therapies have been able to kill targeted cells without damaging surrounding tissue. Although Laroussi has shown in demonstrations for news photographers that he can run his hand through the plume without harming his skin, the same cold plasma has been shown to kill various bacteria including Escherichia coli when the plasma breaks open the cell walls of the bacteria.

Plasmas are soups of neutral atoms/molecules, ions and electrons. In nature, they are generated in solar flares and lightning-anywhere atoms are stripped of their electrons-and have temperatures of thousands of degrees. But Laroussi's plasma pencil and other plasma sources can produce room-temperature plasmas that allow practical applications.

Laroussi is first author of the paper in NJP. His co-authors are D. A. Mendis, an astrophysicist and professor emeritus at the University of California, San Diego, and Marlene Rosenberg of the electrical and computer engineering faculty at UCSD.

This article was posted on: November 6, 2007

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