Probing of bioaffinity interactions at interfaces using impedance spectroscopy and chronopotentiometry

Faradaic impedance spectroscopy and chronopotentiometry are used as electrochemical methods for probing in situ bioaffinity interactions on surfaces between enzymes and their molecular or macromolecular cofactors. Alcohol dehydrogenase (E.C. 1.1.1.1.) and lactate dehydrogenase (E.C. 1.1.1.27) bind to an NAD+-functionalized monolayer electrode with association constants corresponding to 1.6×104 and 1.5×105 M−1, respectively. Cytochrome oxidase binds to an oriented cytochrome c monolayer assembled on an Au electrode with an association constant of Ka=1.2×107 M−1.