Synthesis of reduced graphene oxide-iron nanoparticles with superior enzyme-mimetic activity for biosensing application

Development of enzyme-mimetic catalysts with sustainability and environmental benignancy has gained considerable attention with the growing demands for large-scale applications in recent years. Here, we demonstrate that the reduced graphene oxide (RGO)-iron nanoparticles (INs) can be utilized as the highly active and cost-effective enzyme-mimetic catalysts for the first time, which have been successfully synthesized by a facile iron-self-catalysis process at room temperature. Benefitting from synergetic effects between RGO and INs, the RGO-INs could efficiently catalyze the oxidization of 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of H2O2 to produce a typical color reaction, showing the much better peroxidase-like activity than that of each individual part. The mechanistic insight into the enhanced peroxidase-like activity of the RGO-INs was investigated systematically. On the basis of the enzyme-mimetic activity of the RGO-INs, the simple, sensitive, selective and cost-effective colorimetric assays for the detection of hydrogen peroxide and glucose with naked eyes were successfully established. The RGO-INs showed several prominent advantages, such as facile preparation, low cost, tunability in catalytic activity, and low detection limit, over natural peroxidase or other nanomaterial-based alternatives, holding great potential as enzymatic mimics for biosensing applications.