Fabrication of FeS2/SiO2 Double Mesoporous Hollow Spheres as an Artificial Peroxidase and Rapid Determination of H2O2 and Glutathione.

Nanozymes as one of artificial enzymes show many advantages than natural enzymes. The high Michaelis-Menten constant (Km) to H2O2 is the drawback for nanozymes, which means a high H2O2 concentration to oxidize 3,3',5,5'-tetramethylbenzidine (TMB). For this problem, FeS2/SiO2 double mesoporous hollow spheres (DMHSs) were first synthesized as an artificial peroxidase through a solid reaction. The experimental results demonstrate that Fe3O4 vulcanization and DMHS formation were effective strategies to enhance affinity to H2O2 for the nanozyme. The Km of FeS2/SiO2 DMHSs (H2O2 as the substrate) is 18-fold smaller than that of FeS2 nanoparticles (NPs). The catalytic efficiency (Kcat/Km) of FeS2/SiO2 DMHSs is about 16 times higher than that of FeS2 NPs. FeS2/SiO2 DMHSs can be used as a nanozyme to sensitively and rapidly detect H2O2 and glutathione within 1 min at room temperature.