Homogeneous amperometric immunoassay

A method for determining the concentration of an analyte present in a sample of biological fluid contained in an electrochemical cell equipped with a set of electrodes, said method comprising the steps of:

• a) forming an electroactive complex containing an antigenic analyte chemically bonded to a carrier molecule, said carrier molecule also being chemically bonded to an electroactive molecule capable of transferring a charge to an electrode;
• b) adding the biological fluid, predetermined amounts of the electroactive complex, and an antibody to the analyte to the cell;
• c) applying a voltage across the electrodes and measuring the current in the fluid at different voltage levels to form a voltage/current relationship for the sample fluid;
• and
• d) comparing the voltage/current relationship for the sample fluid with standard voltage/current relationships generated using known amounts of analytes to determine the concentration of analyte present in the sample.