An Amperometric Glucose Biosensor Composed of Prussian Blue, Nafion, and Glucose Oxidase Studied by Flow Injection Analysis

Abstract

The construction and characterization of a glucose biosensor has been implemented in an instrumental chemical analysis course to provide students experience with chemical sensing, electroanalytical methods, and flow injection analysis (FIA). The glucose biosensor was assembled on a glassy carbon electrode by depositing a layer of Prussian blue (PB) electrocatalyst followed by a layer of glucose oxidase (GOx) immobilized in a Nafion film. GOx catalyzed the oxidation of glucose in the presence of dissolved oxygen to yield gluconic acid and hydrogen peroxide. The hydrogen peroxide produced was then electrocatalytically reduced at the PB film with a mild applied potential. The measured cathodic current provided the analytical signal for the glucose biosensor, which was applied to the quantification of glucose levels in soft drinks using FIA techniques. This experiment exposes students to several electroanalytical methods, including amperometry, cyclic voltammetry, and chronocoulometry, as well as methods that are used to measure biosensor response, deposit the PB film, measure the PB film coverage, and examine its electrocatalytic properties. In addition, students gain experience with FIA and the application of an enzyme-based biosensor.