In this work, a sandwich-type electrochemical immunosensor was fabricated to the effective detection of hepatitis B surface antigen (HBsAg). The designed electrochemical immunosensor was based on Au core and Pd shell nanodendrites loaded on amino functionalized molybdenum dioxide nanosheets (Au@Pd NDS/NH-MoO NSs) as the secondary antibody (Ab) label and silver nanoparticles were loaded by electrodeposited (D-Ag NPs) on the surface of electrode as the platform. Because of the synergistic effect and abundant catalytic activity sites provided by surface dendrite structure, Au@Pd NDs were more effective than single gold and palladium nanoparticles in catalytic reduction of hydrogen peroxide (HO). MoO had the good catalytic capacity for reduction of HO and favourable electrical conductivity. Hence, the obtained Au@Pd NDS/NH-MoO NSs were more effective than Au@Pd NDs and NH-MoO NSs in catalytic reduction of hydrogen peroxide attribute to a synergistic effect. Also, Ag NPs with admirable electrical conductivity and biocompatibility were used as sensing platforms and primary antibodies (Ab) carriers, which can accelerate the electron transfer and improve the sensitivity of the immunosensor. Here, the proposed electrochemical immunosensor offered a wide linear interval from 10 fg mL to 100 ng mL and the lower limit of detection of 3.3 fg mL (S/N = 3) for detection of HBsAg under optimal experimental conditions. Furthermore, the accuracy of the actual serum sample analysis was satisfactory, which showed that the electrochemical immunosensor possessed a good application prospect in clinical detection.
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