DUAL-ANTIBODY SYSTEMS FOR THE CONSTRUCTION OF BIOSENSORS

Abstract

We are reviewing a dual-antibody analytical system based on competitive immunoassay methodologies. Two antibodies are immobilized at separate locations: one antibody (Ab-1) recognizing the analyte and analyte-enzyme conjugate, and the other antibody (Ab-2) recognizing the enzyme componentin the conjugate. This dual-antibody system provides twosignals, originating from the analyte-enzyme conjugate bound to Ab-1 and Ab-2, in response to different analyte concentrations in samples. A competitive immunoassay can be performed without separation of bound and unboundanalyte-enzyme conjugate by the user. Three different modifications of the dualantibody system are described: 1) operationin the irreversible mode under equilibrium conditions, 2) measurement in the irreversible mode under non-equilibrium conditions, and 3) continuous monitoring in the reversible mode. The first two modifications can be used for the developmentof disposable probes. The secondsystem is particularly suitable for immunochromatographywith either colorimetric or amperometric signal readout. Thethird principle makesuse ofthe reversibility of binding for antigen-antibody complex formation and can be adapted for slow-response sensors for the continuous measurementoffluctuating concentrations of small analytes in aqueous media streams.