▎ 摘　　要

A novel label-free amperometric immunosensor based on new multilayer film of graphene oxide/ferrocene-chitosan (GO/Fc-CS) nanocomposite and gold nanoparticles (Au NPs) was developed for detecting hepatitis B antigen (HBsAg). A layer-by-layer (LbL) adsorption technique was applied to modify the golden electrode (GE) with multilayer films of GO/Fc-CS and Au NPs. The modified multilayer film ensured the binding of large number of antibodies and enhanced electron transfer, providing a strong electrochemical reversible redox signal to detect current changes. The immunosensor exhibited excellent performance in detecting HBsAg at wide linear range from 0.1 ng/mL to 350 ng/mL, with a detection limit of 0.1 ng/mL. In addition, the immunosensor has promising prospect for its application in clinical practice and early diagnosis, this being due to its attractive performances such as wide linear range, high accuracy, high stability and excellent repeatability.