Introduction
Chemists, materials scientists and others have joined forces to develop nanowire sensors for biological agents.
Bar codes are already ubiquitous in everyday life, and if multidisciplinary research in the US is successful, bar-coded nanowires could soon be used to detect anthrax and a variety of other highly dangerous pathogens in the near future. Researchers at the Lawrence Livermore National Laboratory, University of California at Davis, Stanford University, and Nanoplex Technologies have shown that their biosensing platform works with agents that are widely used to simulate anthrax, smallpox and toxins such as ricin (Angew. Chem. Int. Edn doi:10.1002/anie.200601104; 2006).
The nanowires were made by Nanoplex — a California-based company that has since been taken over by Oxonica — and contain alternate regions of silver and gold along their length. The different optical properties of the silver and gold allow the nanowire to be read like a conventional bar code.
Jeff Tok, a chemist at Livermore, George Dougherty, a materials engineer, and co-workers attached antibodies — proteins that identify and neutralize foreign objects like viruses — to the nanowires. If the antibody that binds to anthrax, for instance, is used, then any anthrax present in the sample being tested will attach to the nanowires.
Additional antibodies that have been tagged with a fluorescent dye are then added to the sample, and these bind to the anthrax. Finally, the optical reflectance and fluorescence of the nanowires are measured to determine which pathogens are present in the sample. By adding different antibodies to nanowires with different bar codes, it is possible to detect more than one pathogen at a time.
"The challenge in pursuing interdisciplinary research lies in keeping everyone focused on the same goal and maintaining an active line of communication," says Tok.
