Electrochemical impedance analysis of adsorption and enzyme kinetics of calf intestine alkaline phosphatase on sam-modified gold electrode

Abstract

In this work, we have explored the potential of electrochemical impedance technique to follow the kinetics of nonspecific adsorption of enzymes on to a self-assembled monolayer (SAM) of 3-mercapto benzoic acid (3-MBZ) formed on gold electrodes. We have also studied kinetics of enzyme-substrate reactions on the immobilized surface using this technique. During the adsorption process, the surface coverage is measured using the imaginary component of the impedance at a given frequency, which was found to follow Langmuir adsorption kinetics. The adsorbed enzyme was then allowed to interact with different concentrations of its substrate and the resulting reaction was followed in real time. Changes in the imaginary component of the impedance at various substrate concentrations have been found to follow Michelis-Menten kinetics. The results show that electrochemical impedance spectroscopy (EIS) is a powerful technique that can be used to follow enzymatic reactions on surfaces in real time. Our results also suggest that this technique has the potential to emerge as an effective immunosensor tool that can be utilized for a large range of enzyme systems.