Enzyme-amplified amperometric detection of DNA using redox mediating films on gold microelectrodes

Joanna Hajdukiewicz*, Susan Boland, Paul Kavanagh, Anna Nowicka, Zbigniew Stojek, Dónal Leech

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)


Here we describe an amperometric assay for enzyme-labeled detection of DNA hybridization based on a redox polymer film, cross-linked and co-immobilized, with a 20-mer oligonucleotide, to pre-adsorbed cysteamine on gold microelectrode surfaces. Hybridization between the immobilized probe DNA and a biotin-modified target DNA (designed from the ssrA gene of Listeria monocytogenes), followed by addition of an enzyme (glucose oxidase)-avidin conjugate and glucose, results in bioelectrocatalytic oxidation of glucose mediated by the redox polymer, generating significant amplification. The use of gold microelectrodes (25 μm, 40 μm, 100 μm diameter), coupled to careful preparation of surfaces, electronic shielding and background subtraction, results in improved analytical performance, compared to that at macroelectrodes, yielding a limit of quantification of ca. 0.6 pM, corresponding to the presence of ca. 2.5 million copies in the 7 μL assay droplet.

Original languageEnglish
Pages (from-to)342-350
Number of pages9
Issue number3-5
Publication statusPublished - Feb 2009
Externally publishedYes


  • DNA hybridization
  • Enzyme-amplified detection
  • Listeria monocytogenes
  • Redox polymer

ASJC Scopus subject areas

  • Analytical Chemistry
  • Electrochemistry


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