Homogeneous specific binding assay device and preformed complex method

Abstract

A homogeneous specific binding assay device, a method for its preparation, and a method for its use in determining a ligand, such as antigen, hapten, or antibody, in a liquid sample. The test device comprises a solid carrier member, such as a fibrous web matrix, e.g., paper, or a polymeric film or gel, incorporated with reagents for a homogeneous specific binding assay system which produces a detectable response, usually an electromagnetic radiation signal, that is a function of the presence or amount of the ligand in the sample. For example, disclosed is a test device for determining a ligand in a liquid sample, comprising (a) a reagent composition including a complex of (i) a labeled conjugate comprising a label component coupled to said ligand or a specific binding analog thereof, and (ii) a specific binding partner for said ligand, said label providing a detectable response, or interacting with a detectant system to provide a detectable response, which is different when the labeled conjugate is bound by said binding partner compared to when it is not so bound, whereby the detectable response is a function of the presence of the ligand in the sample, and (b) a carrier incorporated with said complex. Useful homogeneous specific binding assay systems include those involving enzyme substrate labels, enzyme prosthetic group labels, and enzyme labels. The detectable response preferably is a luminescent, fluorescent, spectrophotometric, or colorimetric response, which is measurable by visual observation or instrument means.