Patent ID: 7803542

Claim:
A detector for assessing the presence of a molecular target comprising: a) an oligonucleotide blocker; b) an oligonucleotide sensor having: a first region complementary to a first region of the blocker, which first regions are capable of forming a first double-stranded complex with the blocker, wherein the first region of the sensor is capable of specifically interacting with the molecular target thereby disrupting the first double-stranded complex; and a second region complementary to a second region of the blocker, wherein the second regions forms a second double-stranded complex that is not disrupted in the presence of the molecular target; and c) an electrode capable of detecting redox signals from a redox moiety covalently attached to either the blocker or the sensor, wherein at least one of the sensor and the blocker is covalently attached to the electrode, wherein when the first double-stranded complex is formed, the redox moiety is in a first state relative to the electrode, and when the first double-stranded complex is disrupted by the molecular target, the redox moiety is in a second state relative to the electrode, wherein the first and second states give rise to distinguishable redox signals detectable by the electrode.