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DNA detection, reagent-free

Electrochemical system may give rise to better microbiologic sensors, say study authors

Jeffrey Perkel(jperkel@the-scientist.com)

A team of researchers at the University of California, Santa Barbara (USCB), has developed a reagentless, electrochemical DNA detection system, according to a report in the early online edition of PNAS.

UCSB postdoctoral fellow Chunhai Fan, assistant professor of chemistry and biochemistry Kevin Plaxco, and 2000 Chemistry Nobel Laureate Alan Heeger modeled their electrochemical DNA sensor on fluorescent molecular beacons. Molecular beacons are stem-loop–forming DNA molecules tagged at one end with a fluorescent dye and at the other with a fluorescent quencher, with a target-specific sequence in between. In the absence of target DNA, the beacon adopts a closed, hairpin-like structure that keeps the dye and quencher in close proximity, dousing fluorescence. When it binds its target, however, the probe unfolds, separating the two ends and producing a measurable light emission.

The team's electrochemical variant involves a stem-loop–forming piece of DNA tethered to a gold electrode to which...

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