Bioinspired amino acid-functionalized cobalt ferrite nanocomposite: A nanozyme-based colorimetric sensor for...

The escalating oxidative stress has heightened the daily human demand for diverse antioxidants. Therefore, development of the novel approaches to assess the total antioxidant capacity (TAC) of various nutrients is essential. In this study, drawing inspiration from the active site of native peroxidase enzymes, a novel peroxidase (POD)-like nanozyme was developed based on the cobalt ferrite (CoFe₂O₄) nanoparticles functionalized with different catalytic amino acids. Based on the TMB/H₂O₂ colorimetric system, the most substantial enhancement in POD-like activity was obtained by the glutamic acid coating among different charged amino acids studied, with more than 74% increase in specific activity compared to the bare CoFe₂O₄. A signal-off colorimetric sensing platform based on the obtained nanobiocatalyst was developed for the accurate quantification of the antioxidant capacity of phenolic compounds and vitamin C. The sensitive and selective quantification of ascorbic acid, tannic acid, gallic acid, cyanidin-3-glucoside, and quercetin was obtained by this colorimetric method.