Biogenic synthesis of magnetic nanozymes with peroxidase-like activity for water remediation

Iron oxide nanoparticles (IONPs) have attracted great attention for different environmental applications, mainly due to their magnetic, enzymatic and adsorption properties. In this study, IONPs functionalized with Betula pendula extract (FIONPs) were synthesized by a simple and green method and fully characterized using FE-SEM, EDS, XRD, TGA, DLS, VSM, and FTIR. The monodisperse and colloidal FIONPs represented a crystal structure and spherical shape, an average hydrodynamic size of 118.4 nm with PDI of 0.52 and zeta potential value of -28.4, and also high saturation magnetization value of 45.3 emu g^-1. The in vitro studies revealed high biocompatibility of FIONPs on the human cell lines and their potent antibacterial effects on S. aureus and E. coli. FIONPs also displayed high peroxidase-like activity with a specific activity of 0.50 mmol min^-1 mg^-1. UV-Vis spectroscopy showed more than 99% removal of crystal violet and methylene blue in the batch experiments in the presence of FIONPs, while HPLC analysis revealed more than 98% degradation of antibiotic cefixime and chlorpyrifos pesticide. Degradation mechanism of chlorpyrifos was further studied by LC-MS analysis and biocompatibility of degradation products was evaluated in vitro. The overall results indicated high potential of FIONPs for pollutant removal from water.