▎ 摘　　要

This work reports a novel electrochemical impedance immunosensor for aflatoxin B1 (AFB1) based on L-cysteine, Au nanoparticles (Au NPs), and porous nitrogen-doped graphene (P-N-r-GO). P-N-r-GO was prepared via the hydrothermal method using 4-aminopyrazolo[3,4-d]pyrimidine as a novel nitrogen source, which was then oxidized in the presence of HNO3 to form a porous structure. Au NPs were electrodeposited on P-N-r-GO modified glassy carbon electrode (GCE). Then, L-cysteine was self-assembled onto the surface of Au NPs with its thiol group, and its amino group and carboxyl group were simultaneously used to covalently combine AFB1 antibody as the same group on the modified electrode using the bidirectional covalence strategy. Finally, an electrochemical immunosensor was constructed using Fe(CN)(6)(3-/4-) to produce impedance signal. The sensor proved to be an excellent sensing platform for AFB1 by exhibiting a linear range of 0.01 ng mL(-1) to 10 ng mL(-1) with a detection limit of 0.001 ng mL(-1).