Electrochemical DNA detecton using indicator-free target DNA on a DNA chip

This research aims to develop an indicator-free DNA chip. We fabricated a DNA microarray by lithography technology. Several probe DNAs consisting of thiol group at their 5´-ends were immobilized on the gold electrodes. Then indicator-free target DNA was hybridized by an electrical force and measured electrochemically in potassium ferricyanide solution. Redox peak of cyclic-voltammogram showed a difference between target DNA and mismatched DNA in an anodic peak current. This indicator-free DNA chip microarray resulted in the sequence-specific detection of the target DNA quantitatively ranging from 10^-18M to 10^-5M in the buffer solution. Therefore, it is able to detect various genes electrochemically after immobilization of various probe DNAs and hybridization of indicator-free DNA on the electrodes simultaneously. It suggested that this DNA chip could recognize the sequence specific genes.