Impedance spectroscopy and affinity measurement of specific antibody–antigen interaction

We use impedance spectroscopy technique to develop a rapid and sensitive antigen biosensor. The biosensor is based on the immobilization of antibodies onto an 11-Mercaptoundecanoic acid self-assembled monolayer. The high insulating properties of the thiol can be measured with cyclic voltammetry and impedance spectroscopy with a redox couple. The, the modified gold electrode is activated with 1-ethyl-3 (3-dimethyl aminopropyl) carbodiimide (EDC) and N-hydroxy succinimide (NHS) ester for antibody immobilisation. The affinity interaction of the antigen–antibody can be measured with quartz crystal microbalance technique. Dissociation and association constant are determined by applying a Fortran program fitting for the experimental data.