Patent ID: 7892816

Claim:
A method for determining the presence or absence of a target substrate in a test sample comprising: providing an electrode comprising: a conductive surface, and a probe that is bound to the conductive surface and is capable of binding to a target substrate; contacting the conductive-surface bound probe with the test sample to form a surface bound target complex if the target substrate is present in the test sample, wherein the surface bound target complex further comprises a redox-catalyst complex that is capable of catalyzing an oxidation-reduction reaction; contacting the surface bound probe or the surface bound target complex, if present, with a fluid medium comprising a redox transition metal complex that is capable of undergoing an oxidation-reduction reaction when the surface bound target complex comprising the redox-catalyst complex is present; detecting the oxidation-reduction reaction of the redox transition metal complex that is at least in part catalyzed by the redox-catalyst complex; and determining the presence or absence of the target substrate in the test sample from the detected oxidation-reduction reaction.