Synthesis of well-dispersed Fe3O4 nanoparticles loaded on montmorillonite and sensitive colorimetric detection of H2O2 based on its peroxidase-like activity

In this study, a simple strategy for the preparation of Fe3O4 nanoparticles (NPs) loaded on montmorillonite as a support is reported. The Fe3O4-MMT nanocomposites (NCs) were demonstrated to possess peroxidase-like activity and could catalyze the oxidation of 3,3,5,5-tetramethylbenzidine (TMB) to a blue oxidation product (oxTMB) in the presence of hydrogen peroxide. The obvious color change can be used to quantify the H2O2 concentration using UV-vis spectroscopy. In addition, the Fe3O4-MMT NCs exhibit enhanced peroxidase-like activity as compared to MMT or pure Fe3O4 NPs. Steady-state kinetics studies and a hydroxyl radical detecting assay were carried out to investigate the peroxidase-like activity and catalytic mechanism of these NCs. Under the optimized conditions, Fe3O4-MMT NCs are expected to be used as a good colorimetric biosensor for the detection of H2O2, which have a linear range from 5 x 10(-5) M to 2 x 10(-4) M with a detectable H2O2 concentration as low as 5.1 x 10(-6) M. This sensor was also successfully applied to detect H2O2 in contact lens solution samples.