Electronic Sensor Detects Minute Amounts of Specific DNA

A recent report describes a new strategy for linking the conformational change that occurs during DNA hybridization to an electronic sensor in order to detect picomolar amounts of specific DNA.

The strategy, published July 16, 2003, in the online edition of the Proceedings of the National Academy of Sciences, involves an electroactive, ferrocene-tagged DNA stem-loop structure that self-assembles onto a gold electrode by means of facile gold-thiol chemistry. Hybridization induces a large conformational change in this surface-confined DNA structure, which in turn significantly alters the electron-transfer tunneling distance between the electrode and the redoxable label. The resulting change in electron transfer efficiency is readily measured by cyclic voltammetry at target DNA concentrations as low as 10 pM. The new detector achieves this impressive sensitivity without the use of exogenous reagents and without sacrificing selectivity or reusability.

"The goal is a DNA sensor that is simple, lightweight, low power, and reusable,” explained contributing author Dr. Kevin W. Plaxco, assistant professor of chemistry and biochemistry at the University of California, Santa Barbara (USA). "The target is to detect certain types of DNA. There are existing techniques that are incredibly sensitive, but they are slow and cumbersome and take hours to days to complete.”



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