Chemistry

A Mercury Bridge

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Science  10 Sep 2004:
Vol. 305, Issue 5690, pp. 1533
DOI: 10.1126/science.305.5690.1533d

Environmental contamination by mercury and other heavy metal ions is a growing problem, and detection requires sensors that are both highly selective and sensitive. Ono and Togashi have developed a DNA-based sensor that meets these requirements. Their 22-nt oligo contains two 9-nt mercury-binding sequences and a 4-nt linker, and is capped by a fluorophore at one end and a fluorescence quencher at the other. When Hg2+ ions bridge apposing thymines, the fluorophore and quencher are brought together in a hairpin configuration, and fluorescence drops. The sensor is more sensitive (40 nM) than previously reported small-molecule sensors and can detect Hg2+ ions even in the presence of a 10-fold excess of other heavy metals. — JFU

Angew. Chem. Int. Ed. 43, 4300 (2004).

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