1 February 2002
'Molecular nose' ferrets out dangerous chemicals
Amherst, Mass.A "molecular nose" that can sense and identify particular chemicals may soon be able to identify bioterror agents such as anthrax or smallpox, said a chemistry professor at the University of Massachusetts in Amherst, Mass.
Professor Vincent Rotello said the science community already has a firm grasp on detecting small molecules. Researchers build chemical structures that link onto the surface of the molecule, the way a key fits into a lock, he said. But larger molecules, or macromolecules, such as those on the surface of a virus or bacterium, present a greater challenge. This is because the shape and topography of the large molecule are much more complex.
"These molecules are often so big that chemists can't build something that fits around them effectively," Rotello said.
Rotello wants to address the problem by combining biology and materials science. The team wants to connect smaller, very specific "keys" into "locks" located along the surface of a macromolecule. The difficulty lies in connecting the "key" to the correct "lock" in exactly the right position. "It's an extremely complex problem, and few good tools exist for dealing with it," Rotello said. "You just can't engineer a solution on an atom-by-atom basis."
The UMass team assembled tiny scaffoldlike structures in an effort to solve the problem. In this case, the tiny gold nanoparticles provide building blocks to construct the chemical "keys." Researchers use gold because it is easy to attach chemical groups to gold surfaces. Once in place, the chemical groups can move, allowing them to selectively bind to the large molecules in exactly the right places, serving as "keys."
A parallel project with the Polymer Science and Engineering department focuses on quartz crystals, similar to those used in everyday wristwatches. "The wristwatch works because the quartz crystal vibrates at very specific frequency, moving the clock mechanism," said Rotello. Using the same concept, researchers are hoping to identify chemical agents by relying on quartz. "A quartz chip weighs more with the agent on it," said Rotello. "The chemical actually slows down the crystal, changing its frequency. If you look at the rate of vibration, you can determine whether a given chemical is present." That project has already seen action detecting environmental pollutants, such as finding PCBs in wells.