High Specificity, Electrochemical Sandwich Assays Based on Single Aptamer Sequences and Suitable for the Direct Detection of Small-Molecule Targets in Blood and Other Complex Matrices

摘要

The double-antibody sandwich assay has become a mainstay of clinical diagnostics. In a typical assay, a specific monoclonal antibody is used to capture a target molecule on the walls of a plastic microtiter plate. A second antibody directed against a second epitope on the same target is then added, forming an antibody-antigen-antibody "sandwich." If the second antibody is linked to an enzyme (ELISA) or radiolabeled (radioimmunoassay), the presence of the target is then readily determined. Because double-antibody sandwich assays require the simultaneous binding of two antibodies, they are extremely specific, rendering them suitable for use directly in complex materials, such as blood serum. Likewise, because signaling is typically coupled to a catalytic (enzymatic) signaling mechanism, the approach often achieves impressive, subnanomolar detection limits for protein targets.