In this study, nitrogen-doped mesoporous carbon-based nanozymes were synthesized. Initially, 3-aminophenol formaldehyde polymer structures were synthesized from the reaction of 3-aminophenol and hexamine as the formaldehyde source in the presence of Pluronic-F127 as a soft template. These polymer structures were then converted into nitrogen doped porous carbon structures through a pyrolysis process under an inert argon atmosphere. Iron and palladium species, both monometallic and bimetallic, were stabilized on these nanostructures using a chemical reduction method. The synthesized structures were characterized using various spectroscopic and analytical techniques such as X-ray diffraction, energy-dispersive X-ray spectroscopy, field emission scanning electron microscopy, and transmission electron microscopy. The peroxidase-like activity of these structures was eva‎luated using colorimetric tests on model compounds, 3,3′,5,5′- tetramethylbenzidine, and o-phenylenediamine. The progress and selectivity of the peroxidase process were studied through UV-Visible spectroscopy. The kinetics of the peroxidase activity of the synthesized nanozymes were analyzed based on the Michaelis-Menten model. In this model, the constants Km and Vmax were determined by measuring the reaction rate as a function of substrate concentration. The Michaelis constant (Km) represents the affinity of the enzyme for the substrate; thus, a lower Km indicates a high affinity of the nanozyme for the substrate, meaning that the reaction occurs at a high rate even at low substrate concentrations. Vmax is the maximum rate that the enzymatic reaction can achieve under full substrate saturation conditions, indicating the overall capacity of the enzyme under ideal conditions where substrate accessibility is not a limitation. The values of Vmax and Km for 3,3′,5,5′-tetramethylbenzidine were calculated to be approximately 0.113 μMmin⁻¹ and 0.156 mM, respectively. Furthermore, these values for o-phenylenediamine were found to be approximately 0.163 μMmin⁻¹ and 0.088 mM, respectively. The low Km and high Vmax values are likely due to the optimized structure and superior electronic properties of this catalyst. Additionally, the results indicated that the bimetallic structure exhibited better peroxidase activity compared to its monometallic counterparts, which can be attributed to synergistic effects between the two metals, palladium and iron.

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حسين توكل

عليرضا نجفي چرمهيني , محمد ديناري