A Novel Electrochemical Glucose Biosensor Based on MnO2/Carboxylated Graphene Oxide/Glucose Oxidase for Sensitive Glucose Biosensing

Abstract

In the study, a novel electrochemical glucose biosensor was conducted depending on the manganese dioxide/carboxylated graphene oxide/glucose oxidase (MnO<inf>2</inf>/f-GO/GOx) modified glassy carbon electrode (GCE). The pseudo-direct electron transfer (pseudo-DET) between electrode and GOx was provided using the working electrode, that is, MnO<inf>2</inf>/f-GO/GOx/GCE as the counter electrode before glucose biosensing. This method was applied to all working electrodes and the results were excellent. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and amperometric methods were used to electrochemically evaluate the biosensor. The CV results demonstrated that GOx immobilized on MnO<inf>2</inf>/f-GO underwent pseudo-DET reaction, and the voltammograms showed a pair of well-described redox peaks with a formal potential of −29.08 ± 2.22 mV. The linear glucose determination range was 0.0016–3.023 mM with limit of detection (LOD) of 0.48 μM and sensitivity of 45.73 ± 1.65 μA mM−1 cm−2. The biosensor exhibited high biological affinity with apparent Michaelis-Menten constant of 4.42 ± 0.8 mM and good stability and repeatability. Additionally, the well- known interfering species, such as ascorbic acid, tryptophan, uric acid, and dopamine, did not show any interference because of the GOx immobilized on MnO<inf>2</inf>/f-GO surface. The MnO<inf>2</inf>/f-GO/GOx/GCE biosensor was used for quantification of glucose in biological fluids. © 2026 Elsevier B.V.