Abstract
In this paper the operation of an amperometric biosensor producing a chemically amplified signal is modelled numerically. The chemical amplification is achieved by using synergistic substrates. The model is based on non-stationary reaction-diffusion equations. The model involves three layers (compartments): a layer of enzyme solution entrapped on the electrode surface, a dialysis membrane covering the enzyme layer and an outer diffusion layer which is modelled by the Nernst approach. The equation system is solved numerically by using the finite difference technique. The biosensor response and sensitivity are investigated by altering the model parameters influencing the enzyme kinetics as well as the mass transport by diffusion. The biosensor action was analyzed with a special emphasis to the effect of the chemical amplification. The simulation results qualitatively explain and confirm the experimentally observed effect of the synergistic substrates conversion on the biosensor response.
Highlights
A biosensor is an electronic measuring device designed for measurement of the concentration of some specific substance in a solution
The dependence of the steady-state biosensor current on the concentration s20 of the substrate S2 was investigated at different diffusion layer thicknesses d3 as well as at different values of the reaction rate constant k3
The biosensor may reliably measure the concentration of substrate S2 at the range of concentrations where the biosensor response is dependent on the concentration s20 but not dependent on the diffusion layer thickness d3
Summary
A biosensor is an electronic measuring device designed for measurement of the concentration of some specific substance (analyte) in a solution. The kinetic analysis of the reaction of a mixture of low and high reactive electron acceptors shows that the reduction of a low reactive electron acceptor may substantially increase if the rate of the cross reaction between these substances is high enough This phenomenon is employed in biosensors for a high sensitivity determination of synergistic substrates [13,14,15]. A laccase-based biosensor utilizing simultaneous substrates conversion was numerically modelled at steady-state as well as transient conditions [27] The goal of this investigation was to develop a computational model for an effective simulation of amperometric biosensors utilizing the synergistic substrates conversion as well as to investigate the influence of the physical and kinetic parameters on the biosensor response. The simulation results qualitatively explained and confirmed the experimentally observed effect of the synergistic substrates conversion on the biosensor response [13]
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