Chemist Alexander Klibanov of the Massachusetts Institute of Technology and his colleagues had already found that the bristly coating of polymers kills bacteria including Escherichia coli and Staphylococcus aureus, which can lie in wait on doorknobs or other surfaces for unsuspecting hands to pick up. To test its effect on the much smaller flu virus, they applied droplets of a flu solution to glass slips painted with the polymer. After a few minutes' exposure, they were unable to recover any active virus from the samples, meaning the coating reduced the pathogen's abundance by at least a factor of 10,000. The group reported their results in a paper published online November 13 by the Proceedings of the National Academy of Sciences USA.
Klibanov says part of their motivation was the ongoing concern over the potential for a deadly global outbreak of flu. "This isn't going to save the world," he says, "but this could potentially be a useful tool." Ideally the polymer coating would be applied to hospital or airplane doors and air filters, surgical gear and anywhere else a pathogen might linger, he says. Touching a contaminated surface can probably spread the flu virus, according to the World Health Organization, although actual instances of such transmission may be rare.
In the case of bacteria, the polymer seems to work by gouging holes in a microbe's cell wall and spilling out its contents. The polymer molecules stay rigid because they are all positively charged and therefore repel each other, like strands of hair standing on end from a static charge. The spikes have sufficiently few charges, however, that they can breach bacterial walls, which repel strongly charged molecules. The polymer probably neutralizes flu because the virus has an envelope around it suitable for spearing, Klibanov says. Although the coating seems nontoxic--it causes no harm to monkey cells in tests--it would still need regulatory approval before becoming commercially available, he adds.
Inventors seem to be working overtime lately on potential germ fighters, from automated spritzers of disinfectant positioned atop doorknobs to prerecorded messages that politely remind you to wash your hands. Some see the polymer approach as nothing but a way to cash in on pandemic flu hysteria. "Frankly I think this method of inactivating flu is a gimmick and lacks any biological significance," says virologist Robert Lamb of Northwestern University. Its creators are naturally more sanguine. The advantage of the polymer coating, Klibanov says, is its potential ubiquity. "The way I look at it is, if you can paint it, we can make it bactericidal"--and virucidal--he says.