IMMUNOASSAY USING DYE COMPLEXED ENZYME CONJUGATES

Target-specific dye labeled complexes are formed by reacting a conjugate of an enzyme and a specific binding substance, such as an antibody or antigen, with an enzyme substrate in a liquid medium under conditions where the substrate is converted to dye molecules which then complex to the conjugate. Such dye labeled complexes are useful in a variety of biological assays, particularly lateral flow assays where the dye labeled complex is immobilized within a label zone (14) which forms part of a flow path for a liquid sample or liquid reagent in a test device (10). Liquid flow through the label zone (14) transports the dye labeled complex to a subsequent capture zone (16) where it is bound in proportion to the presence or absence of a target analyte within the liquid sample.