Triple-enzyme mimetic activity of Co3O4 nanotubes and their applications in colorimetric sensing of glutathione

Abstract

The enzyme-like activity of Co₃O₄ nanomaterials has attracted tremendous interest because of their extraordinarily high electron mobility and catalytic activity. However, there are still some controversies on their catalytic performance. In this work, we prepared Co₃O₄ nanotubes with a large surface area and a uniform nanostructure by electrospinning, and investigated the triple-enzyme mimetic activity of Co₃O₄ nanotubes: oxidase-like activity, peroxidase-like activity and catalase-like activity. Considering different opinions on the oxidase-like activity of Co₃O₄ nanoparticles, we investigated the catalytic oxidation performance and the mechanism of Co₃O₄ nanotubes in detail. The results demonstrated that the Co₃O₄ nanotubes could effectively catalyze the oxidation of substrate 3,3′,5,5′-tetramethylbenzidine (TMB) in the absence of exogenously added H₂O₂ to produce the blue color product oxTMB. The excellent oxidase-like activities of Co₃O₄ nanotubes were probably because of the unique nanostructures and large surface area, which may easily adsorb substrates and give more active reaction sites. In addition, based on the oxidase-like activity of Co₃O₄ nanotubes, a simple and sensitive colorimetric sensor has been developed for the detection of glutathione via the TMB–O₂–Co₃O₄ nanotube system.