UV-Light-Driven Enhancement of Peroxidase-Like Activity of Mg-Aminoclay-Based Fe3O4/TiO2 Hybrids for Colorimetric Detection of Phenolic Compounds

Abstract

Light-activated nanozymes possess several advantages, such as light-mediated activity regulation, utilization of molecular oxygen as a green oxidant, and highly enhanced activity; however, the types of light-activated nanozymes are still limited. In this study, we found that Mg aminoclay-based Fe3O4/TiO2 hybrids (MgAC-Fe3O4/TiO2) exhibited peroxidase-like catalytic activity to catalyze the oxidation of the peroxidase substrate 2,2′-azino-bis(3-ethylbenzo-thiazoline-6-sulfonic acid) diammonium salt (ABTS) in the presence of H2O2, which was significantly enhanced under ultraviolet (UV)-light irradiation. Compared with MgAC-Fe3O4 and MgAC-TiO2, MgAC-Fe3O4/TiO2 showed around three-fold enhancement in the absorption intensity corresponding to the oxidized ABTS under UV-light irradiation, presumably due to the synergistic effect between Fe3O4 and TiO2, thereby facilitating photocatalytic electron transfer during the catalytic action. In addition, the MgAC-Fe3O4/TiO2 showed vivid stability enhancement in wide range of pH and temperature values compared with natural peroxidase. The UV-light-driven MgAC-Fe3O4/TiO2-based system was successfully applied for the colorimetric detection of phenolic compounds, including pyrocatechol and resorcinol, in a dynamic linear range of 0.15–1.30 mg/mL with a limit of detection as low as 0.1 mg/mL. Further, the system could successfully determine the phenolic compounds in spiked tap water, and thus, it can be used for practical applications. We believe that the UV-light-driven enhancement in the peroxidase-like catalytic performances highlights the potential of MgAC-Fe3O4/TiO2 for detecting phenolic compounds as well as other clinically and environmentally important substances.