Chemical dip creates 'killer silk'

A simple chemical treatment can turn ordinary silk into a fabric that kills disease-causing bacteria, including anthrax, a U.S. chemical journal reports. Writing in the American Chemical Society journal Applied Materials & Interfaces, researchers say such a "killer silk," created with an inexpensive dip-and-dry chemical treatment, has a number of potential uses including make-shift curtains and other protective coatings that could protect homes and other buildings in the event of a terrorist attack with anthrax. In adverse conditions, bacteria of the Bacillus species, which includes anthrax, become dormant spores enclosed in a tough coating that can survive heat, radiation, antibiotics and harsh environmental conditions, researcher Rajesh R. Naik said. Certain chemicals can destroy bacteria and have been applied to fabrics like cotton, polyester, nylon and Kevlar, but these treated fabrics are less so against spores. The researchers tried a similar coating on silk to see if it could perform better, developing a chlorinated form of silk by soaking it in a solution that includes a substance similar to household bleach and letting it dry. Silk treated for just an hour killed essentially all of the E. coli bacteria tested on it within 10 minutes and did similarly well against spores of a close anthrax relative used as a stand-in, they said. "Given the potent bactericidal and sporicidal activity of the chlorinated silk fabrics prepared in this study, silk-Cl materials may find use in a variety of applications," the researchers wrote. Other applications could include purifying water in humanitarian relief efforts and in filters or to mitigate the effects of toxic substances, they said.