2.16 - Carbon-Polymer Biocomposites for Amperometric Sensing

Abstract

This chapter describes carbon–polymer biocomposites for amperometric sensing. A survey of potentially suitable polymeric matrices was carried out. Epoxy resins, silicones, methacrylates, polyesters and polyurethanes were tested. For each material, optimal graphite content was determined. The criteria for this evaluation were maximal electrical conductivity without loss of material stability. Atypical ohmic resistance was 1 kΩ, but the optimal graphite content was not constant, even for the same type of polymer. The transducers were characterized electrochemically using cyclic voltammetry and linear-sweep voltammetry. The linear response for hydrogen peroxide was evaluated. They were also studied spectroscopically using FTIR, and microscopically by SEM. The applicability of these conducting polymer composites has been extended to the construction of glucose biosensors where the composite is bulk-modified by glucose oxidase, and where the amperometric detection of hydrogen peroxide serves as the analytical signal. Glucose biosensors have been prepared mixing a redox mediator, enzyme, graphite powder and a polymer. The resulting material modulates electron transfer between the enzyme and the transducer.