This fingertip-shaped group of lights is a microscopic crystal called a quantum dot. About 10,000 times thinner than a sheet of paper, the dot radiates brilliant colors under ultraviolet light. Dots such as this one allow researchers to label and track individual molecules in living cells and may soon be used for speedy disease diagnosis, DNA testing, and screening for illegal drugs. Courtesy of chemist Sandra Rosenthal and postdoctoral fellow James McBride, both at Vanderbilt University; and Stephen Pennycook, a physicist and electron microscopist at Oak Ridge National Laboratory.Featured in the April 18, 2006, issue of Biomedical Beat.
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