An enzymatic biosensor for hydrogen peroxide based on one-pot preparation of CeO2-reduced graphene oxide nanocomposite

Abstract

The study describes cerium oxide-reduced graphene oxide (CeO₂-rGO) prepared by a facile one-pot hydrothermal approach and its assembly with horseradish peroxidase (HRP) for the detection of hydrogen peroxide (H₂O₂) at trace levels. The prepared nanocomposite was characterized by Fourier transform infrared spectroscopy, field-emission scanning electron microscopy, X-ray diffraction, and voltammetry. Furthermore, the direct electrochemistry of HRP/CeO₂-rGO composite has been studied. The immobilized enzyme retained its bioactivity and exhibited a pair of well-defined redox peaks, confirming the direct electron transfer (DET) of HRP with CeO₂-rGO composite modified electrode. A significant enzyme loading (4.270 × 10⁻¹⁰ mol cm⁻²) has been obtained on CeO₂-rGO composite as compared to the bare glassy carbon (GC), CeO₂, and rGO modified surfaces. This HRP/CeO₂-rGO film has been used for the sensitive detection of hydrogen peroxide by voltammetry and it exhibited a wide linear range of H₂O₂ from 0.1 to 500 μM with a detection limit of 0.021 μM. The apparent Michaelis–Menten constant (K^app_M) of HRP on the CeO₂-rGO composite was estimated as 0.011 mM. The combination of the direct electron transfer character of HRP and the promising feature of CeO₂-rGO composite favors the sensitive determination of H₂O₂ with improved sensitivity.