An ultrasensitive electrochemical immunosensor based on the catalytical activity of MoS2-Au composite using Ag nanospheres as labels

We reported here the synthesis of thin MoS2 nanosheets, which showed a good catalysis of H2O2. The MoS2 nanosheets were further synthetized into nano-composite MoS2-Au, and the MoS2-Au was found with a better catalysis property of H2O2 and well electroconductibility. Furthermore, we composed Ag nanospheres (AgNPs), which have good electricity and large surface area. The prepared AgNPs and MoS2-Au were applied in a sandwich-type immunosensor for detecting carcinoembryonic antigen (CEA). In the immunosensor, MoS2-Au acted as the solid support for CEA primary antibody and AgNPs were employed as the supporter of glucose oxidase (GOx) and CEA secondary antibody. With the addition of glucose, the hydrogen peroxide was prepared and the MoS2-Au catalyzed hydrogen peroxide that the current peak was presented with the differential pulse voltammetry (DPV). The proposed immunosensor enabled CEA concentrations to be determined in the range of 1 pg mL−1 to 50 ng mL−1, with a detection limit of 0.27 pg mL−1. The immunosensor showed low detection limit, good specificity, high sensitivity and reproducibility. Satisfactory results were obtained for determination of CEA in human serum albumin samples. This work is to open new avenues in the application of AuNPs dotted MoS2 composite interface for sensitive electrochemical immunoassay. Hence, the proposed electrochemical immunosensor could become a promising method for tumor marker detection.

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