Biotechnology

A Litmus Test for Cocaine

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Science  09 Aug 2002:
Vol. 297, Issue 5583, pp. 899-901
DOI: 10.1126/science.297.5583.899e

Biomolecules are increasingly used to construct sensors for the detection of small molecules, such as drugs or explosives, because of their high sensitivity and selectivity. However, it is not enough that the sensor recognizes and binds the target molecule; the interaction must also result in a detectable signal, ideally a visible color change. Stojanovic and Landry describe a sensor based on an aptamer (an oligonucleotide) previously shown to bind cocaine with selectivity and sensitivity. After screening 35 dyes for color changes upon addition to cocaine-aptamer mixtures, they selected a cyanine compound to prepare their aptamer-dye sensor. When cocaine was added, it displaced the dye, causing a decrease in absorption at 760 nm. The micromolar affinity of the aptamer may prove sufficient for a handheld detection device in the cocaine supply interdiction effort. — JFU

J. Am. Chem. Soc., 10.1021/ja0259483 (2002).

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