Electrochemical gene detection using microelectrode array on a DNA chip

Thirty-two microelectrodes were fabricated onto a glass chip and used for an integrated DNA sensor. Several probe DNAs consisting of mercaptohexyl moiety at their 5' end were immobilized on the gold electrodes by a DNA arrayer. Then target DNAs were hybridized and reacted with Hoechst 33258, which was a DNA minor groove binder and redox-active dye. Linear sweep voltammetry or cyclic voltammetry showed a difference between target DNA and control DNA in the anodic peak current values. It was derived from Hoechst 33258 concentrated at the electrode surface through association with formed hybrid. The DNA sensor obtained by microfabricated electrodes with DNA probes and redox-active DNA intercalator was able to detect 0.1 nM of target sequence and 100 nM of single-base mismatched DNA. Sixteen electrodes that immobilized HIV probes gave higher response in thirty-two electrodes, which immobilized four kinds of DNA probes. These result shows this method can detect target DNA specifically.