The direct electrochemistry of glucose oxidase based on the synergic effect of amino acid ionic liquid and carbon nanotubes

Abstract

Amino acid ionic liquids (AAILs) have attracted much attention due to their special chemical and physical properties, especially their outstanding biocompatibility and truly green aspect. In this work, a novel electrochemical biosensing platform based on AAILs/carbon nanotubes (CNTs) composite was fabricated. AAILs were used as a novel solvent for glucose oxidase (GOD) and the GOD-AAILs/CNTs/GC electrode was conveniently prepared by immersing the carbon nanotubes (CNTs) modified glassy carbon (GC) electrode into AAILs containing GOD. The direct electrochemistry of GOD on the GOD-AAILs/CNTs/GC electrode has been investigated and a pair of reversible peaks was obtained by cyclic voltammetry. The immobilized glucose oxidase could retain bioactivity and catalyze the reduction of dissolved oxygen. Due to the synergic effect of AAILs and CNTs, the GOD-AAILs/CNTs/GC electrode shows excellent electrocatalytic activity towards glucose with a linear range from 0.05 to 0.8 mM and a detection limit of 5.5 µM (S/N = 3). Furthermore, the biosensor exhibits good stability and ability to exclude the interference of commonly coexisting uric and ascorbic acid. Therefore, AAILs/CNTs composite can be a good candidate biocompatible material for the direct electrochemistry of the redox-active enzyme and the construction of third- generation enzyme sensors.