Direct Electrochemical Detection of Oligonucleotide Hybridization on Poly(5-hydroxy-1,4-naphthoquinone- co-5-hydroxy-3thioacetic Acid-1,4-naphthoquinone) Film

We describe the construction of a new DNA-modified electrode based on an electroactive film. 5-Hydroxy-l,4naphthoquinone is coelectrooxidized with 5-hydroxy-3thioacetic acid-l,4-naphthoquinone to give a copolymer, presenting both electroactive and chemically reactive groups. The carboxylic function acts as a precursor for the covalent grafting of ODN probes while the quinone group acts as the transduction element of hybridization. Electrochemical detection was performed by differential pulse voltammetry in the electroactivity domain of the quinone group (i.e., at very low potentials, 0 to -0.8 V vs SCE). A very clear modification of the redox activity is observed between unmodified and probe-modified films and especially upon addition of target ODN.