Investigation of Silver-Doped Iron Oxide Nanostructures Functionalized with Ionic Liquid for Colorimetric Sensing of Hydrogen Peroxide

Hydrogen peroxide (H₂O₂) is a by-product of oxidase-catalyzed reactions that serves as a signaling molecule and can cause DNA and protein damage. This leads to an increase in our susceptibility toward various kinds of diseases including diabetes mellitus and hypertension, The novelty of this work lies in the synergistic effect of all three components of the Ag-Fe₂O₃-IL composite for the colorimetric detection of H₂O₂. Silver-doped iron oxide nanostructures (Ag-Fe₂O₃ NS) were synthesized and then coated with ionic liquid (IL) having peculiar characteristics of aromaticity and conductivity to enhance their properties. The prepared Ag-Fe₂O₃ nanoparticles were characterized through spectroscopic techniques namely FTIR, XRD, SEM and EDX. The characterized Ag-Fe₂O₃ NS and 3, 3', 5, 5' Tetramethylbenzidine (TMB) solutions were employed for the colorimetric sensing of H₂O₂. To optimize the proposed sensor different reaction conditions including (a) amount of Ag-Fe₂O₃NS/IL (b) TMB, (c) pH, (d) H₂O₂ concentration and (e) incubation time were optimized. At optimum conditions, the desired sensor showed a wide linear range 1 × 10⁻⁹–3.2 × 10⁻⁷ M, a lower limit of quantification 3.20 × 10⁻⁷ M, and a limit of detection 1.07 × 10⁻⁸ M with a 0.9996 R² value. The selectivity of the proposed sensor was compared with the potential interfering species and the incubation time was just 5 min. Additionally, the sensor was effectively applied for detecting hydrogen peroxide in the urine samples of diabetes mellitus patients.