Synthesis of Surface-Modification-Oriented Nanosized Molybdenum Disulfide with High Peroxidase-Like Catalytic Activity for H 2 O 2 and Cholesterol Detection.

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.