چكيده لاتين
In recent years, given the important role of enzymes in various industries and their limitations including sensitivity harsh environmental conditions, degradation by proteases, difficult recovery, high production cost, and difficult purification, many efforts have been made to produce alternatives. Due to the development of nanotechnology and the discovery of the catalytic activity mimic of some nanoparticles, nanozymes were recognized as direct substitutes for natural enzymes. Nanozymes, with their unique properties such as stability in harsh environmental conditions, easy and low-cost production, tunable activity, and biocompatibility, have overcome the limitations of natural enzymes and have been widely used in various fields such as industrial, medical, environmental, etc. Morover, one of the environmental problems is water pollution due to pharmaceutical contaminants that cause drug resistance. One of the effective methods for removing pollutants is oxidation by the peroxidase (POD) mimic activity of nanozymes. For this purpose, in this study, iron oxide peroxidase-like nanozymes with a biodegradable and biocompatible chitosan coating were used to degrade the antifungal drug fluconazole. The surface modification of iron oxide nanozymes by chitosan coating was synthesized using a one-step solvothermal method to enhance the peroxidase-like properties and prevent aggregation of nanoparticles during synthesis. The structure, size, morphology, functional groups, crystal structure and thermal stability of nanoparticles were characterized using field emission scanning electron microscopy (FE-SEM), Fourier transform infrared (FTIR), X-ray diffraction (XRD) and thermogravimetric analysis (TGA) assays. Then, the peroxidase-like activity of the nanozymes was investigated by colorimetric method using the substrate 3,3,5,5-tetramethylbenzidine (2mM) and hydrogen peroxide (1M) at pH 3.6. The results showed a 2.3-fold increase in the specific activity of Fe3O4@Ch nanozymes compared to Fe3O4@Ch nanozymes. The peroxidase-like reaction of the nanozymes follows the Michaelis-Menten equation. The Km kinetic parameter obtained for H2O2 and TMB substrates were 639.86 and 0.35 mM, and the vmax for H2O2 and TMB substrates were 17.035 and 11.75 μmol/min, respectively. In the next step, the performance of Fe3O4@Ch nanozymes in the degradation of fluconazole and the effect of reaction conditions including reaction time, pH, initial fluconazole concentration, and H2O2 concentration on the degradation process of fluconazole were investigated. The results showed that Fe3O4@Ch nanozymes under the optimal conditions (pH=6/3, [H2O2]=400mM, [FLC]=0/5mg/ml) remove 87% of FLC within 90 min. This indicates that Fe3O4@Ch nanozyme is a kind of superior Fenton-like catalyst for removal of the contaminant fluconazole from wastewater.
