Patent ID: 7776617

Claim:
A method for testing for the presence of an analyte in a test solution comprising: a) providing a chromatographic strip having a contact end for contacting the test solution and a capture moiety immobilized at a capture zone of the chromatographic strip, the capture moiety comprising a member of a ligand/anti-ligand binding pair capable of binding the analyte, or a derivative thereof, as the other member of the ligand/anti-ligand binding pair, wherein the binding is not by a nucleic acid base pairing interaction; b) contacting the contact end of the chromatographic strip with the test solution to allow analyte, or derivative thereof, to travel to the capture zone by capillary action and be captured by the capture moiety; c) contacting a labeled targeting agent with the capture zone, the labeled targeting agent being capable of binding the analyte, or a derivative thereof, thereby allowing labeled targeting agent to be captured at the capture zone as part of a complex comprising the capture moiety, the analyte or derivative and the labeled targeting agent, wherein the labeled targeting agent comprises a plurality of ligands and each of two or more ligands are bound to a label, and wherein the labels are bound to the ligands before the labeled targeting agent is contacted with the capture zone; and d) detecting for the presence of label at the capture zone.