Immunoassay method, device, and test kit

Abstract

An immunoassay device includes one or more reaction chambers. Each reaction chamber is adapted to receive and retain a volume of test fluid in fluid communication with nonoverlapping first and second reaction surfaces. To the first reaction surface is immobilized analyte binding partner that is in turn saturated with analyte conjugate: analyte component conjugated to one or more components, termed ligand/marker, that serve ligand and marker functions as described herein. The analyte conjugate has a higher disassociation constant with reference to the immobilized analyte binding partner than does the analyte to be assayed. To the second reaction surface is immobilized ligand/marker binding partner. A test fluid sample is introduced into the reaction chamber and retained therein to permit two reactions to occur. In a first reaction between analyte and analyte binding partner at the first reaction reaction surface, analyte proportionately displaces analyte conjugate into the test fluid sample. In a second reaction the displaced analyte conjugate becomes sequestered at the second reaction surface by bonding with immobilized ligand/marker binding partner. Thereafter the marker activity of sequestered analyte analog is measured, the measured activity being a function of the analyte concentration that is referable to standards and controls. A test kit includes the immunoassay device in combination with comparative test results.