%0 Journal Article
%T Analytical Expressions of Concentrations of Substrate and Hydroquinone in an Amperometric Glucose Biosensor
%A M. Uma Maheswari
%A L. Rajendran
%J ISRN Physical Chemistry
%D 2013
%R 10.1155/2013/143870
%X The theoretical model for an amperometric glucose biosensor is discussed. In this model glucose oxidase enzyme is immobilized in conducting polypyrrole. This model contains a nonlinear term related to enzyme reaction kinetics. He¡¯s homotopy perturbation method is used to find the approximate analytical solutions of coupled non-linear reaction diffusion equations. A closed-form expression of substrate and mediator concentration under non-steady-state conditions is obtained. A comparison of the analytical approximation and numerical simulation is also presented. An agreement between analytical expressions and numerical results is observed. 1. Introduction Since the second half of the last century, numerous efforts have been devoted to the development of insoluble immobilized enzymes for a variety of applications [1]. These applications can clearly benefit from use of the immobilized enzymes rather than the soluble counterparts, for instance as reusable heterogeneous biocatalysts, with the aim of reducing production costs by efficient recycling and control of the process [2], as stable and reusable devices for analytical and medical applications [3¨C9], as selective adsorbents for purification of proteins and enzymes [10], as fundamental tools for solid-phase protein chemistry [11, 12], and as effective microdevices for controlled release of protein drugs [13]. Immobilized enzymes are becoming increasingly popular as reusable, selective analytical chemical reagents in solid-phase flow-through reactors, as membranes in sensors, and as films in dry reagent kits. The attractions of immobilized enzymes from an analytical standpoint are primarily their reusability, and hence cost saving, and the greater efficiency and control of their catalytic activity [14] (e.g., potentially longer half-lives, predictable decay rates and more efficient multistep reactions). The immobilization of enzymes in conducting polymer [15] during electro-polymerization step has proved to be well suited to the preparation of biosensors [16¨C19]. This method is simple and easy to control. Another important advantage of this immobilization technique is the possibility of entrapping the mediator in the polymer as a dopant anion [20¨C23] or by covalent fixation on the pyrrole monomer [24]. Bartlett and Whitaker [25] have already presented a theoretical model for an amperometric polypyrrole + glucose oxidase (PPY + GOD) electrode. In their model PPY was considered as an insulating polymer, and the reduced mediator H2O2 was oxidized at the metallic surface after diffusion in the polymer.
%U http://www.hindawi.com/journals/isrn.physical.chemistry/2013/143870/