Direct Enzyme-Amplified Electrical Recognition of a 30-Base Model Oligonucleotide

• Published in: Journal of the American Chemical Society Vol. 118; no. 23; pp. 5504 - 5505
• Main Authors: de Lumley-Woodyear, T, Campbell, C. N, Heller, A
• Format: Journal Article
• Language: English
• Published: American Chemical Society 12.06.1996
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja960490o

Electrochemical sensors recognizing hybridization of DNA strands based on electrogenerated chemiluminescence and cyclic voltammetry of intercalated ruthenium and cobalt complexes and organic dyes and of redox functions covalently bound to single DNA strands have been reported. Also a direct enzyme-amplified amperometric affinity assay for the avidin-biotin conjugate has been described. In this system, bonding of biotinylated horseradish peroxidase to avidin covalently attached to an electron-conducting redox hydrogel resulted in the "wiring" of the enzyme, i.e. its electrical connection to the electrode. Such connection produced an H sub(2)O sub(2) electroreduction current proportional to the number of conjugates. Here we show that the hybridization of a model oligonucleotide can be directly measured as an electrical current. The current flows as a result of continuous electroreduction of H sub(2)O sub(2), electrocatalyzed by the horseradish peroxidase (HRP) label of an oligonucleotide strand when the complementary strand is covalently bound to a hydrogel that electrically "wires" the HRP. In such a hydrogel, electrons diffuse via self-exchange of electrons between colliding segments of the redox polymer network, which become mobile when hydrated.