The Analysis of Zirconium (IV) Oxide (ZrO2) Nanoparticles for Peroxidase Activity

In this study, the peroxidase-like activity of zirconium (IV) oxide nanoparticles (nZr) is reported. Peroxidases catalyze the oxidation of their substrate in the presence of peroxide species. 3,3′,5,5′-tetramethylbenzidine (TMB) is a peroxidase substrate, and we have demonstrated that nZr oxidizes the TMB in the presence of hydrogen peroxide resulting in a colored (TMBox) product. The reaction was tested in various buffers, and sodium acetate with pH 4 was observed to be an ideal buffer for the enzymatic reaction and the dispersity of the nZr in the solution. The nanozyme behavior was studied systematically at three different temperatures (25, 35 and 45 °C) and a wide range of H2O2 concentrations. The dependence of the enzymatic reaction on temperature, nZr content and H2O2 concentration was observed. The enzymatic reaction was tested in different protein solutions and no noticeable interference was observed with these proteins. Overall, we demonstrate that nZr, which is often used for industrial applications, mimics peroxidase enzyme and catalyzes oxidation of its substrate in the presence of peroxide species.