Facile synthesis of IrO2/rGO nanocomposites with high peroxidase-like activity for sensitive colorimetric detection of low weight biothiols

In this work, we reported a novel nanozyme synthesized by decorating highly dispersed ultrafine IrO2 nanoparticles on reduced graphene oxide (rGO) nanosheets via a simple hydrothermal method. The as-prepared IrO2/rGO nanocomposites exhibited intrinsic peroxidase-like activity and could catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) to produce blue product in the presence of H2O2. Catalytic kinetic of IrO2/rGO nanocomposites followed Michaelis-Menten behavior, exhibiting a higher affinity to TMB than horseradish peroxidase (HRP) enzyme. Catalytic mechanism studies suggested that the peroxidase-like activity of IrO2/rGO nanocomposites originated from their ability of electron transfer between substrate and H2O2. On the basis of high peroxidase-like activity of IrO2/rGO nanocomposites, a colorimetric strategy for rapid and sensitive detection of low weight biothiols was developed. The colorimetric detection assays for low weight biothiols showed high selectivity against other amino acids. Therefore, the IrO2/rGO nanozyme is expected for promising potential applications in the biosensor, diagnostics and environment.