ENZYME MIMIC OXIDASE-LIKE ACTIVITY OF Fe_3O_4 MAGNETIC NANOPARTICLES FOR DOPAMINE DETECTION

摘要

Enzyme mimics have garnered substantial attention as they can overcome some severe drawbacks associated with natural enzymes such as inhibition of their catalytic activity. The present study proves that the Fe_3O_4 magnetic nanoparticles (MNPs) exhibit an oxidase-like activity similar to that found in the tyrosinase enzyme. The Fe_5O_4 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 Fe~(2+) and Fe~(3+) in Fe_3O_4 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 Fe_3O_4 NPs were used as a new technique for colorimetric detection of dopamine.