In the present study, a facile method was proposed to prepare nickel sulfide (NiS) nanoparticles well-dispersed on the surface of montmorillonite/graphene oxide (MMT/GO). The NiS/MMT/GO nanocomposites were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), fluorescence spectrophotometry, etc. Significantly, the novel NiS/MMT/GO nanocomposites exhibited high peroxidase-like activity toward the typical chromogenic substrate, 3,3′,5,5′-tetramethylbenzidine (TMB). However, glutathione (GSH) could inhibit the peroxidase-like activity of NiS/ MMT/GO along with a visible color variation. Based on the color change of the system of nanocomposites-H 2 O 2 -TMB, a novel colorimetric sensor was designed and conveniently used to quantitatively detect H 2 O 2 as well as GSH. The limit of detection (LOD) of H 2 O 2 and GSH is 9.73 and 0.5043 μM, respectively. The proposed H 2 O 2 sensor has potential application in the field of biosensing, food, and environment.
For the first time, functional Corrole molecules modified iron oxide (Fe 3 O 4) magnetic nanoparticles (MNPs) were prepared by a facile two-step method. The Corrole-Fe 3 O 4 nanocomposites exhibited a higher peroxidase-like activity than that of pure Fe 3 O 4 nanoparticles, and accelerated the oxidation of peroxidase substrate 3,3',5,5'-tetramethylbenzidine (TMB) with the help of hydrogen peroxide (H 2 O 2) only in 5 min, attributing to hydroxyl radicals (•OH) generated in the process of oxidation of TMB. Kinetic analysis showed that the catalytic behaviors followed the typical Michaelis-Menten kinetics. Additionally, Corrole-Fe 3 O 4 exhibits several advantages including low cost, easy separation, facile fabrication, and high catalytic efficiency. Based on the catalytic activity of Corrole-Fe 3 O 4 nanocomposites, a simple, sensitive, and selective colorimetric biosensor for H 2 O 2 and glucose determination was successfully designed. The linear relationships of absorbance of oxidized TMB at 652 nm with H 2 O 2 or glucose concentration were obtained from 10 μM to 100 μM with a detection limit of 3.6 μM and 4 μM to 40 μM with the detection limit as low as 2.46 μM, respectively. The results demonstrate that the Corrole-Fe 3 O 4 nanocomposites have potential applications in bioanalysis and biodetection.
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