Patent ID: 8679772

Claim:
An immunoassay for detection of a biological species, said immunoassay comprising the steps of: a) providing an electrode comprising a binding antibody and an anchor group, each being coupled to an electrically conductive substrate, said binding antibody being capable of binding to the biological species and said anchor group being capable of binding to a redox polymer; b) exposing the electrode to an analyte liquid putatively containing the biological species so as to couple the biological species, if present in the analyte liquid, to the binding antibody on the electrode; c) exposing the electrode to an antibody-enzyme liquid comprising an antibody-enzyme species, said antibody-enzyme species comprising a detection antibody capable of binding to the biological species, said detection antibody being coupled to a redox enzyme, whereby, if the analyte liquid comprises the biological species, the redox enzyme couples to the electrode by means of the coupling of both the detection antibody and the binding antibody to the biological species; d) exposing the electrode to a polymer solution comprising the redox polymer and to an enzyme substrate, whereby if the redox enzyme is coupled to the biological species on the electrode the redox polymer is reduced and couples to the anchor group on the electrode; and e) applying a voltage between the electrode and a reference electrode and exposing the electrode to an oxidisable species, whereby a magnitude of an electric current between said electrode and a reference electrode is indicative of the presence or absence of the biological species.