WehavedevelopedFe3O4 magnetic nanoparticles/reduced grapheme oxidenano sheets modified glassy carbon (Fe3O4/r-GO/GC) electrodeasanovelsystemforthepreparationofelectrochemicalsensingplatform. Decorating Fe3O4 nanoparticles on grapheme sheets was performed via a facile one-step chemical reaction strategy, wherethereductionofGOandthein-situgenerationofFe3O4 nanoparticles occurred simultaneously. Characterization of as-made nanocomposite using X-ray diffraction (XRD), transmission electron microscopy (TEM) and alternative gradient force magnetometry (AGFM) clearly demonstrate the successful attachment of mono disperse Fe3O4 nanoparticles to grapheme sheets. Electrochemical studiesrevealedthattheFe3O4/r-GO/GCelectrodepossessexcellentelectrocatalyticactivities toward the low potential oxidation of NADH (0.05Vvs.Ag/AgCl) as well asthecatalytic reduction ofO2 and H2O2 at reduced over potentials. Via immobilization of lactate dehydrogenase (LDH) as a model dehydrogenase enzyme on to the Fe3O4/r-GO/GC electrode surface, the ability of modified electrode for biosensing lactate was demonstrated. Inaddition, using differential pulse voltammetry (DPV) to investigate the electrochemical oxidation behavior of ascorbic acid (AA), dopamine(DA) anduric acid (UA)atFe3O4/r-GO/G Celectrode, the high electro catalytic activity of the modified electrode towards imultaneous detection of the secom pounds was indicated. Finally, based on the strong electro catalytic action of Fe3O4/r-GO/GC electrode toward both oxidation and reduction of nitrite, a sensitive amperometric sensor for nitrite determination was proposed. The Fe3O4/r-GO hybrid presented here showing favor able electrochemical features may hold great promise to the development of electrochemical sensors, molecular bioelectronic devices, biosensors and biofuelcells.
