Catalase-Based Modified Graphite Electrode for Hydrogen Peroxide Detection in Different Beverages

A catalase-based (NAF/MWCNTs) nanocomposite film modified glassy carbon electrode for hydrogen peroxide (H₂O₂) detection was developed. The developed biosensor was characterized in terms of its bioelectrochemical properties. Cyclic voltammetry (CV) technique was employed to study the redox features of the enzyme in the absence and in the presence of nanomaterials dispersed in Nafion® polymeric solution. The electron transfer coefficient, α, and the electron transfer rate constant, k , were found to be 0.42 and 1.71 s^-1, at pH 7.0, respectively. Subsequently, the same modification steps were applied to mesoporous graphite screen-printed electrodes. Also, these electrodes were characterized in terms of their main electrochemical and kinetic parameters. The biosensor performances improved considerably after modification with nanomaterials. Moreover, the association of Nafion with carbon nanotubes retained the biological activity of the redox protein. The enzyme electrode response was linear in the range 2.5-1150 μmol L^-1, with LOD of 0.83 μmol L^-1. From the experimental data, we can assess the possibility of using the modified biosensor as a useful tool for H₂O₂ determination in packaged beverages.