MONOCLONAL ANTIBODY-BASED DUAL-LABEL TIME-RESOLVED FLUOROMETRIC ASSAYS IN A SIMPLIFIED ONE-STEP FORMAT

We have performed a one-step all-in-one dual-label dry reagent time-re solved fluorometric assay measuring free and total prostate-specific a ntigen (PSA). ALI assay-specific components were predried in an ordina ry microtitration well, including the Eu and Tb chelate-labeled monocl onal antibodies for the recognition of free and total PSA, respectivel y. Only the sample and assay buffer needed to be added. Optimally, equ ilibrium was reached in <15 min. New intrinsically fluorescent Eu and Tb chelates were used, which made it possible to read the fluorescence directly from the solid phase, The developed dual-label assay with th e simple protocol is ideal for easy automation, as the reaction wells can be of alternative design. The performance characteristics are equi valent to those of the present state-of-the-art single-label assays, T he detection limits for free and total PSA were 0.03 and 0.02 mu g/L, respectively, and the assays were linear over the range tested (up to 300 mu g/L).