Bio-Electrocatalytic Reduction of Hydrogen Peroxide by Peroxidase from Guinea Grass (Panicum Maximum) Immobilized on Graphene and Graphene Oxide Screen-Printed Electrodesª

Objective: In this article a comparison was made between graphene (SPGE) and graphene oxide screen-printed electrodes (SPGOE) to study the bio-electrocatalytic reduction of hydrogen peroxide (H₂O₂) by guinea grass peroxidase (GGP). Methods and materials: GGP was immobilized onto SPGE and SPGOE by a drop-casting procedure. Electrochemical techniques were carried out to monitor the electrochemical behavior of GGP and the efficiency of electrocatalytic reduction of H₂O₂. Results and discussion: GGP adsorbed on both electrodes exhibited a couple of well-defined redox peaks at 120 mV/10.5 mV and 184 mV/59 mV for anodic and cathodic peaks, respectively. Linearity between scan rates root and oxidation and reduction peak currents for both electrodes suggest a surface-controlled process. The GGP-modified electrodes exhibited a good electrocatalytic activity to H₂O₂ reduction at a redox potential of-0.6 V and-0.5 V for SPEG and SPEGO, respectively. Conclusions: SPGE and SPGOE electrodes modified with GGP showed excellent analytical performance towards different concentrations of hydrogen peroxide. This is a preliminary step to developing a bio-analytical portable system based on GGP for the detection of H₂O₂ in real environmental samples.