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Anal Chem. 2009 Dec 15;81(24):10007-12. doi: 10.1021/ac9018507.

Potentiometric detection of DNA hybridization using enzyme-induced metallization and a silver ion selective electrode.

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Department of Nanoengineering, University of California San Diego, La Jolla, California 92093, USA.


Here, we report on a highly sensitive potentiometric detection of DNA hybridization. The new assay uses a low-volume solid-contact silver ion-selective electrode (Ag(+)-ISE) to monitor the depletion of silver ions induced by the biocatalytic reaction of the alkaline-phosphatase enzyme tag. The resultant potential change of the Ag(+)-ISE, thus, serves as the hybridization signal. Factors affecting the potentiometric hybridization response have been optimized to offer a detection limit of 50 fM (0.2 amol) DNA target. The new potentiometric assay was applied successfully to the monitoring of the 16S rRNA of E. coli pathogenic bacteria to achieve a low detection limit of 10 CFU in the 4 microL sample. Such potentiometric transduction of biocatalytically induced metallization processes holds great promise for monitoring various bioaffinity assays involving common enzyme tags.

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