IMMUNOASSAY APPARATUS AND METHODS

摘要

A method and apparatus for fluorescent immunoassay utilizes total internal reflection at the interface between a solid phase and a liquid phase of lower index of refraction to produce an evanescent wave in the liquid phase. The solid phase is arranged and illuminated so as to provide multiple total internal reflections at he interface. In a preferred embodiment, the solid phase is in the form of an optical fiber (10) to which is immobilized a component of the complex formed in the immunochemical reaction. A fluorophore is attached to another component of the complex. The fluorescent labelled component may be either the complement to or an analog of the immobilized component, depending or whether competitive or sandwich assays are to be performed. In the case of competitive or sandwich assays are to be performed. In the case of competitive assays, the labelled component is preferably pre-loaded to the immobilized component in a controlled concentration. The fiber (and the attached constituent of the assay) is immersed in the liquid phase sample (12). The evanescent wave is used to excite fluorescence in the liquid phase, and that fluorescence which tunnels back into the solid phase and accumulates during multiple reflections while channeled in the solid phase detected. Diffusional preconcentration onto the reactive surface and double passing enhance the signal and signal/background ratio.