Enhancement of the peroxidase-like activity of cerium-doped ferrite nanoparticles for colorimetric detection of H2O2 and glucose

In this report, cerium doped-ferrite nanoparticles (Ce-Fe3O4 NPs), a novel ceria nanostructure, were proposed to have intrinsic peroxidase-like activity toward a classic peroxidase substrate in the presence of H2O2. The peroxidase-like activity of ceria originated from its facile redox behavior (Ce3+/Ce4+) as a catalytic center, thereby explaining the high performance of ferrite-ceria as an artificial enzyme mimicking peroxidase. The as-prepared Ce-Fe3O4 NPs were first demonstrated to possess intrinsic peroxidase-like activity, enhancing the oxidation of the substrate 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of either added H2O2 or H2O2 produced by the enzymatic oxidation of glucose, producing a blue product which could be seen by the naked eye. Based on this, we have successfully established a novel platform for the colorimetric detection of H2O2 with a detection limit of 0.6 mu M. Furthermore, the Ce-Fe3O4 NP-based platform can also be used for highly sensitive and selective detection of glucose with a linear range of 5.0-150.0 mu M and a detection limit of 1.2 mu M.