| The biosensor is an important scientific detection technology in current scientific research because it involves multidisciplinary. Among many biosensors, the electrochemical biosensor has been widely used in clinical medicine, environmental monitoring, agriculture analysis, food safety, and other fields due to its fast response, high sensitivity, high selectivity, ease of operation, low costand so on. Meanwhile, nanomaterials can be used as electrode modifiers, which can be used to build new electrochemical biosensors due to their excellent electrical conductivity, biocompatibility, electrocatalysis, large specific surface area and other properties. Nanomaterials can greatly improve the sensitivity and specificity of electrochemical biosensors. This research mainly focuses on the preparation of molybdenum disulfide（MoS2）-based nanocomposites and their application in electrochemical biosensors. This work successfully synthesize gold nanoparticles-decorated MoS2（AuNPs@MoS2） and gold nanoparticles as well as thionine co-functionalized MoS2（AuNP-ThiMoS2） nanocomposites. On the basis of synthesis, an electrochemical enzyme biosensor and an electrochemical immunosensor are constructed based on these nanocomposites. The specific researches are as the following:（1） AuNP@MoS2 nanocomposites not only maintain the biological activity of hemoglobin（Hb）, but also faciliate electron transfer between the electrode and Hb. The direct electrochemistry of Hb was obtained at AuNP@ MoS2 nanocomposites film modified electrode. Moreover, the modified electrode showed good electrocatalytic ability toward the reduction of hydrogen peroxide（H2O2） and nitric oxide（NO）. Under optimal conditions, the current response was linear with the concentration of H2O2 and NO in the range from 10 μM to 300 μM and 10 μM to 1100 μM with a detection limit of 4 μM and 5 μM, respectively. This MoS2-based biosensor was sensitive, reproducible and stable.（2） A facile approach for synthesis of shape-controlled gold nanoparticle（AuNP）-decorated thionine-MoS2 nanocomposites（AuNP-Thi-MoS2） had been reported by using the synergistic effect of MoS2 and Thi. Thi was not only used as an electrochemical indicator, but also as a reducing agent to tune the resulting morphologies of AuNPs. With the ratio of MoS2/Thi decreasing, the shapes of AuNPs changed from spherical, triangle, clover-like to flower-like nanostructures. TEM, XRD and XPS were employed to characterize the formation and chemical composition of clover-like AuNPThi-MoS2 nanocomposites. All the results showed that the AuNP-Thi-MoS2 nanocomposites has been successful synthesized.（3） On the basis of synthesis, a label-free electrochemical immunosensor had been designed to detect carcino-embryonic antigen（CEA） based on clover-like AuNP-Thi-MoS2 nanocomposites. The current response of Thi was linear with the concentration of CEA in the range from 1 pg mL-1 to 10 ng mL-1 with a detection limit of 0.52 pg mL-1. Moreover, the expected immunosensor showed high stability and excellent reproducibility, which could detect CEA in human serum with satisfactory results. |
