Graphene oxide-based Fe2O3 hybrid enzyme mimetic with enhanced peroxidase and catalase-like activities

Graphene based materials are widely used in energy conversation and catalytic reaction due to their rapid electron transfer capacity and large surface area. Herein, graphene Fe2O3 (GO-Fe2O3) hybrids with enhanced peroxidase-like activity were fabricated. Enhanced peroxidase-like activity strongly depending on pH, temperature and hybrid concentration was observed and the peroxidase-like behavior fits well the Michaelis-Menten kinetic model. Free radicals, such as (OH)-O-center dot and O-2(-center dot), as intermediates in the hybrid-H2O2 reaction system were directly demonstrated by electron spin resonance (ESR) technique and the selective radical inhibition experiments. Furthermore, it was found that the addition of TMB rapidly consumed (OH)-O-center dot and Of(center dot), and subsequently leaded to the formation of blue TMB radical confirmed by the ESR and absorption spectroscopy. Besides acting as mimetic peroxidase in acidic buffer, the GO-Fe2O3 hybrids also displayed the enhanced catalase-like activity in neutral and alkaline buffers compared with individual Fe2O3 nanoparticles and GO sheet, respectively. The H2O2 decomposition catalyzed by the hybrids was demonstrated by ESR and the generated O-2 was measured using the dissolved oxygen electrode. All the results above demonstrate that the GO-Fe2O3 hybrids are a kind of effective pH-dependent mimetic dual-enzyme. (C) 2016 Elsevier B.V. All rights reserved.