Membrane-based displacement flow immunoassay

A continuous flow displacement immunoassay has been developed in order to detect nanomolar quantities of two explosives (TNT and RDX). Antibodies are immobilized onto a porous membrane with surface reactive sites designed to facilitate the covalent binding of the antibody. Having saturated the immobilized antibody with labeled antigen, the target analyte is introduced and the displacement reactions are monitored using a fluorimeter. The displaced labeled antigen detected is proportional to the concentration of the analyte introduced into the column. Multiple assays were performed using columns containing individual membranes. Sensitivity limits were in the low nanomolar range