Abstract

This study investigates the use of a redox mediator system to enhance the pollutant remediation capabilities of laccase-like nanozymes. A three-phase magnetic nanocomposite, composed of MnFe2O4, Mn3O4, and CuO in various precursor ratios, was synthesized. The 1:2:2 nanocomposite demonstrated the highest specific laccaselike activity, with values of 8.9 U mg(-1) at pH 4 and 9.2 U mg(-1) at pH 5. In contrast, single-phase nanozymes exhibited much lower activities. Cyclic voltammetry (CV) revealed that the 1:2:2 composite had a MnFe3O4 core and a Mn3O4|CuO alloy shell. The study also evaluated natural and synthetic redox mediators-acetosyringone, syringaldehyde, vanillin, and 1-hydroxybenzotriazole (HBT)-for their effect on methyl orange degradation. Acetosyringone was the most effective, achieving near-complete degradation at 50 mu M and above, resulting in a 6.3-fold increase in degradation rate compared to treatments without mediators. Syringaldehyde and vanillin also enhanced degradation, with syringaldehyde reaching near-complete degradation at 75 mu M and 100 mu M, while vanillin required higher concentrations for 80 % degradation. CV was used to analyze the electrochemical properties of reactions involving the 1:2:2 nanocomposite and redox mediators. These findings highlight the potential of combining nanozymes with natural redox mediators for improved degradation of harmful compounds in environmental remediation. While laccase-like nanozymes have typically been used for sensor applications, this study opens new possibilities for their use in environmental challenges and catalytic systems.