Ru Complex Ion Induces Anomalous Enhancement of Electrochemical Charge Transfer

Electrochemical impedance spectroscopy (EIS) is a highly sensitive observation technique to detect the state of electrode surfaces in solution. A small amount of [Ru(bpy)2DPPZ]2+, a well-known DNA intercalator and fluorescent light switch, has been found to abnormally increase the charge transfer of the mediator [Fe(CN)6]3-/4- at the surface of carbon electrodes. When a very small amount of the Ru complex is added to the EIS solution, a large impedance decrease occurs. This phenomenon is caused by the carbon electrode, the mediator [Fe(CN)6]3-/4- and [Ru(bpy)2DPPZ]2+. No other agents are necessary. By adding [Fe(CN)6]3−/4− and a very small amount of [Ru(bpy)2DPPZ]2+ to the PCR solution, EIS measurements using a PVA-coated carbon electrode could monitor PCR progress in real-time as an increase in impedance.