Microwave-assisted ultrafast synthesis of an iron-based biomolecule-templated nanozyme with augmented peroxidase-mimetic activity†

Abstract

Recently, the inadequacies of natural enzymes, such as high production cost, reduced stability, and strenuous preparation methods, have been addressed by fabricating artificial nanozymes with exceptional stability, availability, and low production cost. Herein, a rapid, cost-effective, facile, and one-pot microwave-assisted synthesis was used to fabricate hemin/graphene nanocomposites (GF) as a nanozyme with peroxidase mimetic activity. During the process, hemin acted as the iron source to synthesize iron oxide nanoparticles (∼50 nm) uniformly decorated on the surface of reduced graphene oxide (rGO). Compared with rGO alone, the fabricated GF demonstrated an augmented capability to catalyse the reaction of colourless pyrogallol (Py) to its deep yellow oxidized product in the presence of hydrogen peroxide (H₂O₂). The focused synthetic approach resulted in high catalytic efficiency of the fabricated nanozyme in decomposing hydrogen peroxide with a ratio of 2 : 1 (graphene : hemin). The formed nanozymes were superparamagnetic with a magnetic moment (M_s) of ∼10.8 emu g⁻¹. Additionally, the biocompatibility of the nanozyme was assessed on NIH3T3 skin fibroblast cells, where no cytotoxicity was witnessed, showing potential for the utility of the developed nanozyme for biomedical applications. This work implies an innovative approach to synthesizing enzyme-mimetic nanozymes using in situ microwave-assisted fabrication with applications in biomedicine, biocatalysis, and biosensing.