A new, nanometer-sized biosensor can detect a single deadly bacterium in tainted ground beef. How? Researchers attached nanoparticles, each packed with thousands of dye molecules, to an antibody that recognizes the microbe E. coli O157:H7. When the nanoball-antibody combo comes into contact with the E. coli bacterium, it glows. Here is the transition, a single bacterial cell glows brightly when it encounters nanoparticle-antibody biosensors, each packed with thousands of dye molecules. Courtesy of Weihong Tan, professor of chemistry at the University of Florida in Gainesville. Featured in the March 15, 2005, issue of Biomedical Beat. High res. image (972 KB TIFF)