Importance of diffusional constraints for the quantitative evaluation of calibration curves of enzymatic micro- and nanoelectrochemical sensors

Abstract

Electrochemical calibration curves recorded at enzyme-modified micro- or nanoelectrodes are often quantitatively analysed using graphical approaches. In this case the information is directly derived from the calibration curve using a frequent practice although it is rooted on extrapolating the procedures valid when the enzymes as well as their substrate and cofactors are homogeneously distributed in a solution. Here, using a simple but highly representative model we demonstrate that this practice yields incorrect interpretation of the experimental results even for simple Michaelis-Menten mechanisms. This model makes it possible to establish correct relationships linking calibration currents and bulk substrate concentrations by a simple method allowing to account for the biases due to diffusional constraints.