Alexander Oleinick

Abstract:

Electrochemical calibration curves recorded at enzyme-modified micro- or nanoelectrodes are often quantitatively analysed using graphical approaches directly inspired from the practice widely used in enzymatic analysis when enzymes as well as their substrate and cofactors are homogeneously distributed in the electrolytic solution [1-3]. 

We will introduce a concise and simple but highly representative model [4] that demonstrates that this practice yields incorrect interpretation of the experimental results even for simple Michaelis-Menten mechanisms. The present modelling makes it possible to establish the correct relationships linking calibration currents and bulk substrate concentrations by a simple method allowing to take into account the biases due to diffusional constraints when steady or quasi-steady state conditions are achieved as occurs experimentally during calibrations of micro- and nanoelectrochemical sensors.

These correct relationships provide kinetic data characterizing a given sensor that ought to be considered whenever a calibrated enzymatic electrochemical sensor is aimed to be used under non-steady state condition, e.g., as for monitoring transient concentration releases of target analytes under in vivo or pseudo in vivo conditions.