FeVO4/reduced graphene oxide: a novel robust peroxidase nanozyme. Application to fabricate an electrochemical glucose biosensor

Abstract

Herein, a FeVO4/reduced graphene oxide (FeVO4/rGO) nanocomposite was synthesized via a surfactant-assisted hydrothermal method and applied as a bifunctional platform for non-enzymatic H2O2 sensing and substrate-competitive enzymatic glucose detection. In this synthesis, sodium dodecylbenzene sulfonate (SDBS) acted as a structure-directing agent to facilitate the uniform distribution of FeVO4 nanocrystals on the rGO network, thereby minimizing restacking and increasing the electroactive surface area. As a peroxidase-mimicking nanozyme, the FeVO4/rGO composite enabled the sensitive detection of H2O2via a hydroxyl radical-mediated electro-reduction mechanism. Michaelis–Menten kinetic analysis yielded a low Michaelis constant (Km) of 0.176 mM and Imax of 52.66 µA, indicating high substrate affinity and catalytic efficiency. Based on this activity, the H2O2 sensor achieved a low limit of detection (LOD) of 0.15 µM, and high sensitivity (2560 µA mM−1 cm−2). Furthermore, a highly efficient cathodic glucose biosensor was fabricated by immobilizing glucose oxidase (GOx) onto the FeVO4/rGO's surface. This bio-hybrid platform demonstrated high performance, achieving a linear concentration range from 0.05 to 1.0 mM with a remarkably low LOD of 0.06 µM and a sensitivity of 89.08 µA mM−1 cm−2. The glucose sensor displayed stability and selectivity against common interferents, and their practical applicability was validated in human urine samples. These results indicate that FeVO4/rGO is a potential material for the development of clinical diagnostic devices.