Finding Anthrax in the Field

BIOWEAPON DETECTION

First responders arriving at the scene of a biological attack may soon have a new tool to help them distinguish between deadly anthrax spores and innocuous white powder. A team at Northwestern University has developed a quick way to detect an anthrax biomarker using a battery-powered, portable Raman spectrometer (J. Am. Chem. Soc., published online March 8, http://dx. doi.org/10.1021/ja043623b).

Although there are a number of methods for identifying anthrax, few lend themselves to use in the field, according to chemistry professor Richard P. Van Duyne, who spearheaded the effort. Most anthrax detection methods either can't be performed outside the laboratory, take too long, or require a relatively large amount of anthrax spores.

Van Duyne reports that the procedure developed in his lab takes only 11 minutes and is sensitive enough to detect about 2,600 anthrax spores--about one-quarter the infectious dose of 10,000 spores. "We are by no means at the end of our development cycle," he adds. "I think we can easily go to a factor of 10 times more sensitive and 10 times faster."

The anthrax detection protocol developed by Van Duyne and graduate students Xiaoyu Zhang, Matthew A. Young, and Olga Lyandres uses surface-enhanced Raman spectroscopy (SERS) to detect calcium dipicolonate, a compound found in the protective layers of anthrax spores. SERS has been used to detect anthrax in the past, Van Duyne notes, but by using a specialized substrate made of nanospheres coated with a silver film, his group was able to speed up SERS detection and increase its sensitivity by a factor of 200.

Van Duyne tells C&EN that the project's original goal was to study fundamental aspects of surface Raman scattering. "This is a perfect example of a basic research project that could provide a great deal of societal good," he says.