STEADY-STATE KINETICS OF THE OPERATION OF ELECTROCHEMICAL MEMBRANE BIOSENSORS USING MULTIENZYME CONVERSIONS OF AN ANALYTE SUBSTRATE

We have obtained generalized expressions for the steady-state response of a potentiometric and an amperometric multienzyme sensor using consecutive conversions of the analyte substrate over a broad substrate concentration range. We have derived relations determining the effect of the biocatalytic and diffusional phase parameters of the components of the biosensor coating on its operating characteristics. We have shown that when the sensitivity of the biosensors to variation in the concentration of the analyte substrate is constant, the diffusion numbers for the enzymes are kinetically indistinguishable within the range of all their values. We have established that when one of the diffusion members dominates over the rest, the multi-enzyme sensor is reduced to a one-enzyme biosensor; when diffusion-controlled catalysis conditions are satisfied for all the enzymes except for one or two key enzymes, then the multienzyme sensor is reduced to respectively a one-enzyme or a two-enzyme biosensor.