Binding assays.

摘要

A method of carrying out a binding assay (e.g. immunoassay) comprises treating the aqueous reaction mixture, subsequent to the binding interaction, with a reactant (e.g. an enzyme) which interacts preferentially with a labelled version of one or other of the binding reagents when said reagent is either bound in a complex or more usually in the free state, to give rise to a product having solubility properties which are substantially different from those of the original binding reagent or complex, thereafter partitioning hydrophobic substances from the treated reaction mixture into a hydrophobic solvent phase and detecting or determining labelled material present in the hydrophobic phase. The method, which is particularly applicable to the immunoassay of hormones and drugs and their hydrophilic metabolite conjugates, relies upon the differential accessibility to reaction of one or other of the binding reagents when in the free state as compared with the bound state and utilises this to selectively alter the solubility properties of either bound or free material to facilitate a liquid-liquid partition to separate labeled free and bound material. This liquid-liquid separation replaces the solid phase separation step of previous assays advantageously providing a pseudo-homogeneous binding assay. Also the partition separation advantageously separates labelled material from luminescently or fluorescently-active contaminants contained in the aqueous sample and is thus desirable for use with luminescent and fluorescent labelled immunoassay procedures.