Patent ID: 7855054

Claim:
A method for detecting a target molecule that may be present in a test sample, the method comprising: (a) preparing a mixture by contacting the test sample with an aptamer comprising a first tag and having a specific affinity for the target molecule, wherein an aptamer affinity complex is formed if said target molecule is present in said test sample, wherein said aptamer comprises at least one modified nucleotide independently selected from the group consisting of 5-(N-benzylcarboxyamide)-2′-deoxyuridine, 5-(N-isobutylcarboxyamide)-2′-deoxyuridine, 5-(N-tryptaminocarboxyamide)-2′-deoxyuridine and 5-(N-naphthylmethylcarboxyamide)-2′-deoxyuridine; (b) exposing the mixture to a first solid support comprising a first capture element, and allowing the first tag to associate with the first capture element; (c) removing any components of the mixture not associated with said first solid support; (d) releasing the aptamer affinity complex from said first solid support; (e) attaching a second tag to said target molecule in the aptamer affinity complex; (f) exposing the released aptamer affinity complex to a second solid support comprising a second capture element and allowing the second tag to associate with said second capture element; (g) removing any uncomplexed aptamer from said mixture by partitioning the uncomplexed aptamer from said aptamer affinity complex; and (h) detecting said target molecule by detecting the aptamer portion of said aptamer affinity complex.