Worried about the bacteria in your water? Just dip a test-strip coated with a special mix of nanoparticles into your glass, and watch the result. If the strip changes color, don't drink. Researchers at the Georgia Institute of Technology and the University of Massachusetts have devised a way to instantly identify several species of bacteria using a blend of charged polymers and gold dust. The implications are fairly staggering for medicine, but also for national security.

I spoke with one of the researchers, Professor Vincent M. Rotello of the UMass Department of Chemistry, who foresees its use in medicine as a far more efficient bacteria test than today's "put it in a petri dish and wait" method. He also explained plans for a device usable in the fields of environmental protection or homeland security:

Our methodology should also be useful for environmental applications, including contamination of water and food through bioterrorism or less nefarious routes. We are thinking of a test-strip method, where you dip the strip into the solution to be analyzed, or alternatively rub against a surface, put it in the instrument and read out [the result].


Here's how it works: The researchers took a negatively charged polymer that fluoresces and combined it with gold nanoparticles, which suppressed the fluorescence. When the substance came in contact with bacteria, which are inherently negatively charged, the polymer was displaced from the gold nanoparticles, allowing it to fluoresce again. Photo by: Argonne National Laboratory.

Rapid and Efficient Identification of Bacteria Using Gold-Nanoparticle-Poly(para-phenyleneethynylene) Constructs. [Angewandte Chemie International Edition.]