Model of a pH‐Based Potentiometric Biosensor Immobilizing Organophosphorus Hydrolase

Abstract

A model for predicting the steady-state response of a pH-based potentiometric biosensor immobilizing organophosphorus hydrolase (OPH) is developed. The model combines the processes of diffusion and enzymatic reaction in the membrane. Key factors influencing the system response, such as enzyme reaction order, Thiele modulus, and buffer concentration are discussed in detail. It is possible to obtain a good linear response by designing an enzyme electrode with a high enough Thiele modulus and by appropriately controlling added buffer concentrations. It is found that the model is in reasonable agreement with the experiment results.

A Theoretical Model of pH-Based Potentiometric Biosensor Based on Immobilized Enzyme Membrane

“…The complete description of the problem is given in [4] [10]. For the sake of completeness the brief description is given in this section and Appendix-A.…”

“…In the enzyme membrane, the reaction-diffusion equations for the concentration of species for non-steady state condition can be represented as follows [4] [10]. ,…”

“…By introducing the following set of dimensionless variables 2 2 max 2 ; ; ; .11) and defining the following "composite species" [10] […”

Analysis of a pH‐Based Potentiometric Biosensor Using the Homotopy Perturbation Method

“…Models of pH-based potentiometric enzyme electrodes immobilizing enzymes other than OPH have been reported [16,17]. Recently, Huanlin and coworkers [1] have developed a numerical model for predicting the steady-state response of a pH-based potentiometric biosensor immobilizing OPH. To our knowledge, no rigorous analytical solution for the concentration of the substrate has been reported.…”

“…Normally, it is not possible to measure the concentration of substrates inside the enzyme membrane with analytical devices. Thus, mathematical models of biosensors have been developed and used as an important tool to study their analytical characteristics.Enzyme-based electrochemical biosensors are attractive for the determination of organophosphorus pesticides (OP) [1][2][3][4][5]. Recently organophosphorus hydrolase (OPH) has been applied instead of acetylcholineesterase (AChE) or butyrylcholinesterase (BChE) in biosensors for the determination of OP.…”