ENZYME MIMIC OXIDASE-LIKE ACTIVITY OF Fe3O4 MAGNETIC NANOPARTICLES FOR DOPAMINE DETECTION

Enzyme mimics have garnered substantial attention as they can overcome some severe drawbacks associated with nat- ural enzymes such as inhibition of their catalytic activity. The present study proves that the Fe3O4 magnetic nanoparticles (MNPs) exhibit an oxidase-like activity similar to that found in the tyrosinase enzyme. The Fe3O4 nanoparticles (NPs) were prepared by the solvothermal method and characterized by Fourier transform infrared, X-ray diffraction, scanning electron microscopy with energy dispersive X-ray, X-ray photoelectron spectroscopy (XPS), and dynamic light scattering/zeta potential techniques to know the structural properties of MNPs. XPS analysis shows that the enzyme mimetic activity of NPs is due to Fe2+ and Fe3+ in Fe3O4 nanoparticle systems. Colorless dopamine forms colored dopamine-o-quinone due to surface modification of MNPs as well as both σ- and π-donor bonding contribution to overall stability. Enzyme mimetics Fe3O4 NPs were used as a new technique for colorimetric detection of dopamine.