Impedimetric IgG-Biosensor with In-Situ Generation of the Redox-Probe

For most electrochemical impedance spectroscopy measurements Ferro-/Ferricyanide is used as redox-probe, but it has limitations in its application for biosensors based on gold electrodes because of chemical degradation induced by the Ferro-/Ferricyanide. The in-situ reduction of [Ru(NH3)6]3+ to [Ru(NH3)6]2+ by means of a direct current during EIS measurements is introduced to generate a stable redox-probe for biosensors. This method of enhanced EIS measurement has been applied to determine the charge transfer resistance of a human-IgG biosensor with a linear range from 0.9 to 50 mg/L IgG.