Electrochemical Detection of Single-Nucleotide Mismatches Using an Electrode Microarray

Xiaohong Li,†‡ Jeremy S. Lee,*† and Heinz-Bernhard Kraatz*‡
Department of Biochemistry, University of Saskatchewan, 107 Wiggins Road, Saskatoon, Saskatchewan, Canada S7N 5E5, and Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, Saskatchewan, Canada S7N 5C9
Anal. Chem., 2006, 78 (17), pp 6096–6101
DOI: 10.1021/ac060533b
Publication Date (Web): July 28, 2006
Copyright © 2006 American Chemical Society
†

 Department of Biochemistry.

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‡

 Department of Chemistry.

,
*

In papers with more than one author, the asterisk indicates the name of the author to whom inquiries about the paper should be addressed.

Abstract

Gold electrode arrays with electrode diameters of 10 μm were used for the detection of eight single-nucleotide mismatches in unlabeled and prehybridized DNA by electrochemical impedance spectroscopy (EIS). Because of the differences in the electrical properties of films of duplex DNA (normal duplex DNA in B-form) in the presence and absence of Zn2+ at pH ≥ 8.6, Randles equivalent circuits were employed to evaluate the EIS results. The difference in the charge-transfer resistance (ΔRCT) between B-DNA (absence of Zn2+ at pH ≥ 8.6) and M-DNA (presence of Zn2+ at pH ≥ 8.6) allows unequivocal detection of all eight single-nucleotide mismatches within a 20-mer DNA sequence. After dehybridization/rehybridization with target DNA, ΔRCT allows the discrimination of single-nucleotide mismatches with concentrations of the target strand as low as 10 fM. Although the presence of protein impurities (bovine serum albumin, 10 μg/mL) interferes with the detection of the target strand (1 pM detection limit), the presence of nontarget DNA (calf thymus DNA, 10-8 M) does not interfere, and the detection limit for recognition of the target strand remains at 10 fM.

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History

  • Published In Issue September 01, 2006
  • Received for review March 23, 2006. Accepted June 26, 2006.

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