γ-Fe2O3 nanozyme-based dual colorimetric sensor for hydrogen peroxide and vitamin C detection: application to
Yudum Tepeli Büyüksünetçi1, Hatice Öztürk1, Mirsu Yurdagül1
1Department of Chemistry, Faculty of Science, Mugla Sitki Kocman University, Kotekli-Mugla, Türkiye. yudumtepeli@mu.edu.tr.
Abstract:
Ascorbic acid (AA), also known as vitamin C, is an essential water-soluble vitamin involved in collagen biosynthesis, immune function, and protection against oxidative stress. Due to its strong antioxidant properties, AA is widely used in cosmetic formulations and nutraceutical products; however, its susceptibility to oxidation necessitates reliable analytical methods for quality control and product authentication. In this study, a simple colorimetric sensing platform based on the peroxidase-like activity of γ-Fe2O3 nanozymes was developed for the detection of AA. γ-Fe2O3 catalyzed the H2O2-mediated oxidation of TMB, producing a blue-colored oxidized product. In the presence of AA, the oxidized TMB was reduced, resulting in a decrease in absorbance at 654 nm. This decrease was proportional to the AA concentration, enabling the sensitive quantification of AA. To the best of our knowledge, this is the first report demonstrating the application of a γ-Fe2O3 nanozyme-based colorimetric sensor for AA determination in commercial dermatological vitamin C serums and dietary supplements. After optimizing the nanozyme amount, incubation time, and reaction temperature, the proposed AA sensor exhibited a linear range of 1.4 nM to 14 µM, with a good correlation coefficient (R2 = 0.95) and a detection limit of 7.24 nM. The method was also evaluated for its tolerance to potential matrix interferences present in commercial vitamin C formulations, as well as to urea as an individual interfering agent, and demonstrated satisfactory tolerance. Practical applicability was validated by analyzing five commercial vitamin C-containing skincare serums and one dietary supplement, achieving recoveries of 97.95-104.12% for cosmetic samples and 91.0% for the supplement. These results demonstrate that the proposed γ-Fe2O3 nanozyme-based colorimetric platform provides a rapid, sensitive, reliable, and cost-effective approach for AA determination in complex commercial matrices.
