Profs develop anthrax detection

Fears over a series of anthrax contaminations shortly after the Sept. 11, 2001 terrorist attacks shut down post offices and federal buildings, sparking concerns over the danger of a biological terrorist attack. But thanks to the work of scientists at the University and Texas A&M, a new method promises to detect anthrax in milliseconds.

Mechanical and aerospace engineering (MAE) professor Marlan Scully, who holds a joint appointment at Texas A&M, led two teams to modify a preexisting technique used to identify the small concentrations of molecules, called coherent anti-Raman scattering (CARS), to make the technology useful in detecting anthrax.

"[Scully] got interested in this project in 2002, during the anthrax attacks," said Dr. Robert Muravski, who worked on the project with teams at Texas A&M. "He saw a way to use quantum optics, which has been his field of expertise for something like 40 years, to detect anthrax."

CARS is a method used to detect low concentrations of a molecule based on its "chemical fingerprint," the unique signal it emits when excited by photons. A laser beam is used to excite the sample, such as air that may contain anthrax, and the sample's response can be used to determine its contents.

A potential problem with the existing technology, however, is that background noise from other molecules in the sample can obscure the results of the testing technique.

Yu Huang 'GS, an MAE graduate student who worked on the project, said that detecting anthrax using the technique would have been impossible prior to the researchers' modifications to the existing CARS technology. "The novel part of our technique is ... using pulses to create molecular vibrations," Huang said.

Each molecule has a distinct frequency at which it creates very strong vibrations called resonance. This resonance makes the molecule's signature easier to pick out from background noise. The researchers tested the method of using pulses to create vibrations on a molecule characteristic of anthrax spores to ensure its efficacy.

"This technique eliminates the drawbacks of CARS," said Arthur Dogariu, a research chemist at the Princeton Institute for the Science and Technology of Materials, who assisted in the project. "Now, we can detect anthrax in milliseconds."

"The goal would be to have a real working device, either in airport security or postal security," Muravski said. "The next step would be developing this method into a device." Further applications are also possible. "It essentially works for just about any chemical, so we could look at biological or environmental problems, like looking for emissions from smokestacks."

That both research groups worked under supervision of Scully was somewhat unusual, though effective, Dogariu said. "We'd send results back and forth and work off each other's leads," he said. The teams have produced a further refinement of their technique, which will be published in the near future.

The project was funded by the Defense Advanced Research Projects Agency, which is responsible for developing cutting-edge technology for the military. The findings were published in the April 13 issue of Science.