چكيده لاتين
The increasing prevalence of oxidative stress, primarily due to industrial lifestyles, has highlighted the urgent need for a variety of antioxidants in human diets. Consequently, the development of accurate and novel methods to assess the antioxidant capacity of diverse food substances has become a crucial research priority. In this context, nanozymes, with their enzyme-like characteristics, have emerged as promising alternatives to natural enzymes in the design of nanobiosensors. This study investigated the enhancement of catalytic activity in cobalt ferrite nanoparticles through amino acid coating, inspired by the active site of natural peroxidase enzymes. The resulting nanocatalyst was subsequently utilized to quantify the antioxidant capacity of various food substances. A colorimetric system, relying on the oxidation and color change of TMB in the presence of H₂O₂, was employed to assess the peroxidase-like activity of the modified nanoparticles. Among the studied amino acids, glutamic acid coating demonstrated the most significant impact, leading to a substantial 74% increase in specific activity. In the second stage, the effect of glutamic acid coating on the binding capacity of nanoparticles to substrates was investigated by comparing kinetic parameters, including νmax and Km. Results revealed a 61% enhancement in the binding affinity of the nanozyme to the TMB substrate following glutamic acid coating. Furthermore, the νmax for both H₂O₂ and TMB substrates increased by approximately 20% and 100%, respectively. To optimize the catalytic performance of the modified nanozyme, the influence of reaction parameters such as temperature, pH, and nanoparticle concentration were investigated. The optimized nanozyme was subsequently integrated into a colorimetric system for the quantitative determination of antioxidant capacity in phenolic compounds and ascorbic acid. The system demonstrated exceptional sensitivity and selectivity for the detection of various antioxidants, with limits of detection of 2, 1.5, 0.02, 0.5, and 0.6 µM for ascorbic acid, gallic acid, tannic acid, cyanidin-3-glucoside, and quercetin, respectively, at pH 3.6. Additionally, the IC₅₀ values of the antioxidants varied at different pH levels, emphasizing the significance of environmental conditions in antioxidant evaluations. In conclusion, this research underscores the potential of engineered nanozymes as a versatile tool for the development of colorimetric methods to assess antioxidant capacity. The innovative approach presented in this study could pave the way for advancements in antioxidant evaluation methods, leading to the development of more effective dietary supplements and pharmaceuticals to combat oxidative stress.
