DIRECT-DETECTION OF BIOMOLECULES BY ELECTROCHEMICAL IMPEDANCE MEASUREMENTS

Accurate, early, fast diagnosis of many diseases requires the direct detection of biomolecules such as immunospecies. Until now, in situ studies have consisted in analysing capacitance variations or optical properties. In this work, electrochemical impedance measurements at various frequencies have been performed on p-Si/SiO2/polymer/grafted antibody/solution heterostructures with or without an antigen. The in-phase impedance change appears to be a specific signal correlated to the antibody/antigen binding. This key parameter is consistent with the specificity, reversibility and kinetics of that interaction. High signal sensitivity will allow the direct titration of the antigen and better knowledge of the structural parameters involved in the antibody/antigen interaction.