Label-free electrochemical detection of DNA hybridization on gold electrode

A label-free electrochemical detection protocol for DNA hybridization is reported for the first time by using a gold electrode (AuE). The oxidation signal of guanine was monitored at +0.73 V by using square wave voltammetry (SWV) on self-assembled L-cysteine monolayer (SAM) modified AuE. The electrochemical determination of hybridization between an inosine substituted capture probe and native target DNA was also accomplished. 6-mer adenine probe was covalently attached to SAM via its amino link at 5' end. Then, 6-mer thymine-tag of the capture probe was hybridized with the adenine probe, thus left the rest of the oligonucleotide available for hybridization with the target. The dependence of the guanine signal upon the concentration of the target was observed. Probe modified AuE was also challenged with non-complementary and mismatch containing oligonucletides. Label-free detection of hybridization on AuE is greatly advantageous over the existing carbon and mercury electrode materials, because of its potential applicability to microfabrication techniques. Performance characteristics of the genosensor are described, along with future prospects. (C) 2003 Published by Elsevier B.V.