Smells like DNA

Science News,  Feb 2, 2008  by Ewen Callaway

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By reshuffling the chemical letters of the genetic code, scientists have made short strands of DNA that can distinguish several different smells, such as explosives and food preservatives.

The new artificial-nose technology could eventually sniff out bombs or a bad batch of chardonnay, says John Kauer, a neuroscientist at Tufts University in Boston. He and colleague Joel White have launched a company called Cogniscent to commercialize their device.

Their artificial nose isn't made of whole genes, which are thousands of letters, or nucleotides, long. Instead, the nose uses short combinations of the chemical units (A, C, T and G) that build DNA, Kauer's team reports in the January PLoS Biology.

When the DNA molecules catch a whiff of something, a fluorescent dye attached to the DNA brightens or dims. On the basis of a combination of DNA molecules that respond to a smell, scientists can tell an explosive like dinitrotoluene, a precursor to TNT, from alcohol. The DNA molecules are printed onto a silkscreen and read by a light scanner.

The molecular nose is an improvement over other technologies because of the vast number of different combinations that can be formed with DNA, says Kauer. The 20to 24-letter strands his team uses can make hundreds of billions of different smell-sensing molecules.

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