Electrochemical detection of surface hybridization of oligodeoxynucleotides bearing anthraquinone tags at gold electrodes

Gold electrodes modified with a DNA 20-mer via a thiol linkage were shown to efficiently capture the complementary 20-mer that was tagged with anthraquinone (AQ) reporter groups. Treatment of the electrodes with 2-mercaptoethanol was required for both efficient surface hybridization and for reversible electron transfer between the gold electrode and the tethered anthraquinone tag. In addition, slow thermal annealing through the melting temperature of the duplex increased the efficiency of the process. Electrodes that had been modified with a ds-DNA bearing AQ tags gave slightly greater voltammetric signals, but after dissociation of the duplex were not as effective as the ss-DNA in capturing the complementary 20-mer from the buffer solutions.