Biosensor Based on Screen-Printed Electrode and Glucose-Oxidase Modified with the Addition of Single-Walled Carbon Nanotubes and Thermoexpanded Graphite

Abstract

The modification of an electrode produced by a matrix printing head with the use of glucose oxidase (GOD), single-walled carbon nanotubes (SWCNTs), and thermoexpanded graphite (TEG) has been studied. During glucose oxidation, modification by SWCNTs leads to the effect of direct electron transfer. Both nanomaterials increase the magnitude of the sensitivity coefficient (SC) from 0.11 to 0.24 mA M^–1 in the case of glucose oxidase–and ferrocene-based electrodes when modification is done with the addition of TEG and up to 0.62 mA M^–1 when modification is done with the addition of SWCNTs. A comparison of the characteristics of the biosensors with ferrocene and nanomaterials with those of the mediator-free biosensors based on SWCNTs and GOD shows that the biosensor provides higher sensitivity detection; the magnitude of sensitivity coefficient is 1.5 mA M^–1. The higher magnitude of the SC can be explained by the occurrence of more effective electron transfer from active centers of the enzyme to the electrode. Voltammetric measurements demonstrate that electron transfer in a mediator-free biosensor is not complicated by a chemical reaction and is carried out under the control of diffusion factors. After testing the mediator-free biosensor in practice, it is possible to talk about the applicability of such a biosensor in detecting glucose in different environments, including the fermentation industry.