Self-assembly of glucose oxidase on reduced graphene oxide-magnetic nanoparticles nanocomposite-based direct electrochemistry for reagentless glucose biosensor

Highlights

• The RGO-Fe₃O₄/GOD nanocomposite was entrapped on MSPE by magnetic field.

• Glucose oxidase immobilized on RGO-Fe₃O₄ via electrostatic interaction without a binder.

• A stable and highly selective of glucose biosensor based on direct electron transfer.

• The biosensor could avoid the possible interferences.

Abstract

A novel approach of the immobilization of a highly selective and stable glucose biosensor based on direct electrochemistry was fabricated by a self-assembly of glucose oxidase (GOD) on reduced graphene oxide (RGO) covalently conjugated to magnetic nanoparticles (Fe₃O₄ NPs) modified on a magnetic screen-printed electrode (MSPE). The RGO-Fe₃O₄ nanocomposite has remarkable enhancement in large surface areas, is favorable environment for enzyme immobilization, facilitates electron transfer between enzymes and electrode surfaces and possesses superparamagnetism property. The morphology and electrochemical properties of RGO-Fe₃O₄/GOD were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, cyclic voltammetry (CV) and amperometry. The modified electrode was a fast, direct electron transfer with an apparent electron transfer rate constant (k_s) of 13.78 s^− 1. The proposed biosensor showed fast amperometric response (3 s) to glucose with a wide linear range from 0.05 to 1 mM, a low detection limit of 0.1 μM at a signal to noise ratio of 3 (S/N = 3) and good sensitivity (5.9 μA/mM). The resulting biosensor has high stability, good reproducibility, excellent selectivity and successfully applied detection potential at − 0.45 V. This mediatorless glucose sensing used the advantages of covalent bonding and self-assembly as a new approach for immobilizing enzymes without any binder. It would be worth noting that it opens a new avenue for fabricating excellent electrochemical biosensors.

Novelty statement

This is a new approach that reporting the immobilization of glucose oxidase on reduced graphene oxide (RGO) covalently conjugated to magnetic nanoparticles (Fe₃O₄ NPs) by electrostatic interaction and modified screen printed electrode. We propose the reagentless with fabrication method without binder and adhesive agents for immobilized enzyme. Fe₃O₄ NPs increasing surface area to enhance the immobilization and prevent the leaching of enzymes at electrode surfaces by magnetic stickers which is improve the stability of the biosensor. Based on this synthesis technique, it is a good new strategy and simple used to fabrication of third-generation glucose biosensor and this nanocomposite could be used as a platform for disposable biosensor and biofuel cell applications.