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 t o efficiently capture the complementary 20-mer that was tagged with anthraq uinone (AQ) reporter groups. Treatment of the electrodes with 2-mercaptoeth anol was required for both efficient surface hybridization and for reversib le electron transfer between the gold electrode and the tethered anthraquin one tag. In addition, slow thermal annealing through the melting temperatur e of the duplex increased the efficiency of the process. Electrodes that ha d been modified with a ds-DNA bearing AQ tags gave slightly greater voltamm etric signals, but after dissociation of the duplex were nor as effective a s the ss-DNA in capturing the complementary 20-mer from the buffer solution s.