Patent ID: 7851149

Claim:
A method for detecting a target analyte in a sample, the method comprising: (a) providing a non-conductive substrate having at least one pair of electrically conductive electrodes and a gap between the at least one pair of electrically conductive electrodes and at least one capturing agent that specifically binds to a binding site of the target analyte, the at least one capturing agent being immobilized on the surface of the substrate in the gap between the electrically conductive electrodes, the at least one capturing agent comprising an oligonucleotide that can bind to the binding site of the target analyte; (b) forming a pretreated sample by adding a nucleation center containing a gold particle to said sample and providing conditions effective to couple the target analyte to the nucleation center; (c) contacting the substrate and the pretreated sample under hybridizing conditions effective to bind the target analyte to the at least one capturing agent; (d) adding a treatment composition to the substrate, the treatment composition comprising a gold providing agent and a reducing agent, whereby gold atoms are released from the gold providing agent and deposited on the nucleation center and wherein the treatment composition is kinetically stable so that gold atoms are not deposited unless a nucleation center is present; and (e) determining one or more of the extent of an electrical contact between the electrodes or the existence of an electrical contact between the electrodes.