The Oxidase Mimicking Activity of MnOx NPs/Co3O4 NPs Hybrid Nanozyme for Glucose Oxidation

Abstract

Herein, the hybrid nanozyme MnOx NPs/Co3O4 NPs on indium tin oxide coated glass substrate (ITO) was manufactured by imparting the porous morphology with its distinct merits: its surface valence states, oxygen vacancies, large surface area, and abundant active sites. The oxidase-like activity was investigated via the catalytic oxidation of chromogenic substrate in the presence of glucose visualized by the eyes. MnOx NPs containing Mn2+ and Mn3+ have a superior ability to oxidize glucose by reducing dissolved oxygen and producing H2O2. Co3O4 NPs, in turn, reduce H2O2 with concomitant 3,3′,5,5′-tetramethylbenzidine (TMB) oxidization. Thus, the nanozyme mimics the dual roles of glucose oxidase and peroxidase. The oxidase-like activity of hybrid nanozyme for glucose was found to be higher than those of single components. The nanozyme responded to glucose with a linear range from 60 µM to 1200 μM. The acceptable performance is probably due to the facilitated access of glucose to the proximity of the sensor surface. Good reproducibility was accomplished by virtue of the meticulous construction of NPs. Without functionalization and enzyme utilization, the fabricated nanozyme holds promise as a substitute for peroxidase and oxidase for detecting glucose.