Immunoassay using electrochemical detection

A method for detecting analyte in a sample comprising:

• a) providing an electrochemical sensor comprising;
• a control sensing element,
• a detection sensing element and
• a magnet which selectively attracts magnetic beads to the detection sensing element relative to the control sensing element,
• wherein upon exposure to a detection solution, each sensing element produces a signal which is indicative of the amount of an enzymatic label present in the detection solution at the sensing element,
• b) exposing the sensing elements to a detection solution,
• wherein the detection solution comprises;
• i) a sample being tested for the presence of analyte
• ii) a detection antibody reactive with said analyte which is attached to the enzymatic label, and
• iii) a separation antibody reactive with said analyte which is attached to a magnetic bead,
• such that, in the presence of analyte in the sample, a immunocomplex is formed in the detection solution which comprises the analyte, the detection and separation antibodies, the enzymatic label and the magnetic bead, and;
• c) measuring the signals produced by the detection and control sensing elements, and
• d) determining from said signals the amount of enzymatic label in the detection solution at the detection sensing element and the control sensing element,
• wherein an increase in the amount of enzymatic label at the detection sensing element relative to the control sensing element is indicative of the presence or amount of analyte in the sample.