Colloidal gold particle concentration immunoassay

Abstract

A sandwich immunoassay method is disclosed that is useful for the identification of an antigen in biological specimens. The method is comprised of a colloidal gold labeled binder specific for epitopes or receptors of a ligand, nonporous particulate solid phase which have antiligand covalently attached, and which said reagents are combined with the biological specimen or an extract of the biological specimen, and after an appropriate incubation, the said reactant mixture is contacted to a porous film having an exposed surface area of contact no greater than 30 mm.sup.2 to separate and concentrate the particle bound colloidal gold labeled binder from the unbound. The identification of an antigen is determined by the presence of color on the surface of the solid phase particles captured on the surface of the film. A competitive inhibition assay can be also used to identify the presence of a hapten or antigen, in which case the presence of the analyte is determined by the absence of color.

Dependencies are inferred from the claim text.