Synthesis of Surface-Modification-Oriented Nanosized Molybdenum Disulfide with High Peroxidase-Like Catalytic...

Abnormal H₂ O₂ and cholesterol levels are closely related to many diseases. This work reports a facile process for the synthesis of oxidized glutathione (GSSG)-modified MoS₂ nanosheets (MoS₂ -GSSG NSs). The biocompatible MoS₂ -GSSG NSs have good dispersibility and high affinity to the substrate 3,3',5,5'-tetramethylbenzidine (TMB), which is beneficial for improving peroxidase-like catalytic activity of MoS₂ . The high peroxidase-like activity of MoS₂ -GSSG NSs was applied as a robust nanoplatform for low-cost, rapid, and highly effective colorimetric detection of H₂ O₂ and total/free cholesterol. Moreover, the peroxidase-like catalytic mechanism was studied by the steady-state kinetics method. The catalytic activity was remarkably high at a wide range of pH (2.4-7.0) and temperature values (25-70 °C). The cholesterol was catalyzed by cholesterol oxidase (ChOx) in the presence of O₂ to generate H₂ O₂ , which oxidized TMB to generate a blue-colored product (oxTMB) under the catalysis of MoS₂ -GSSG NSs. The detection limit (DL) of total cholesterol and H₂ O₂ was as low as 5.36 and 0.51 μm, respectively. The linear ranges for detecting cholesterol and H₂ O₂ were from 5.36 to 800 μm and from 0.51 to 50 μm, respectively. This method was also successfully applied to the detection of cholesterol in serum. The detection concentration of total cholesterol was consistent with that of the value detected by the blood biochemical method used in the clinic.