Nanotech 2005 Vol. 1
Nanotech 2005 Vol. 1
Technical Proceedings of the 2005 NSTI Nanotechnology Conference and Trade Show, Volume 1

Bio Micro Sensors Chapter 8

Electrochemical Detection of Single-Nucleotide Mismatches: Application of M-DNA

Authors: E. Abu-Irhayem, Y-T. Long, T. Sutherland, C-Z Li, H-B Kraatz and J.S. Lee

Affilation: University of Saskatchewan, Canada

Pages: 430 - 433

Keywords: DNA sensors, DNA mismatch, M-DNA, AC impedance

The detection of a single-nucleotide mismatch in a 20 base pair duplex DNA, using Electrochemical Impedance Spectroscopy, is presented. Mismatched DNA monolayers on Au electrodes were studied as normal duplex DNA (B-DNA) and after conversion to zinc metalated duplex DNA (M-DNA). Modeling of the impedance data to an equivalent circuit provides parameters that are useful in discriminating each monolayer configuration. The conversion to M-DNA caused a decrease in the resistance to charge transfer (RCT). Contrary to expectations, RCT for B-DNA was also found to decrease for duplexes containing a mismatch. Further, a method to form loosely-packed single-stranded (ss)-DNA monolayers, by duplex dehybridization, that are able to rehybridize to target strands, was developed. Rehybridization efficiencies were in the range of 40-70%. Under incomplete hybridization conditions, the RCT was the same for matched and mismatched duplexes under B-DNA conditions. However, the difference in RCT between B- and M-DNA, under incomplete hybridization, still provided a distinction. The RCT for a perfect duplex was 76(12) Ohm•cm2, whereas a mismatch in the middle of the sequence yielded a RCT value of 30(15) Ohm•cm2. The detection limit was measured and the impedance methodology reliably detected single DNA base pair mismatches at concentrations as low as 100 pM.

Electrochemical Detection of Single-Nucleotide Mismatches: Application of M-DNA

ISBN: 0-9767985-0-6
Pages: 844
Hardcopy: $109.95