Multiplex assay using distinguishably tagged ligands

摘要

The assay method comprises providing at least two different and distinguishably tagged ligands in a predetermined ratio, at least a first of said ligands being capable of specifically binding with the analyte, contacting the ligands and sample to form a body including a complex involving at least said first ligand and said analyte and contemporaneously quantitatively and separately measuring such of each of said tags as is coupled only to bound ligands in said body. If the relative non-specific binding characteristics of the ligands with respect to the assay apparatus are known, the binding of the first ligand to the analyte can be determined. When three differently tagged ligands are used, the first two may bind to different sites on the same analyte or to different analytes. The assay apparatus includes a reaction surface on which the first ligand(s) may be immobilised and which may be a surface of an attenuated total reflection cell.