▎ 摘　　要

Epizootic ulcerative syndrome (EUS) that is primarily caused by an invasive oomycete fungus Aphanomyces invadans is a devastating fish disease. Rapid diagnosis of EUS is significantly important for the control and treatment of this highly invasive disease. In our study, a label-free immunosensor constructed with G-AuNPs/SAM-Ab-BSA/GCE was proposed for the determination of Aphanomyces invadans. The electrode was prepared by the immobilization of anti-mycelium antibodies on graphene-AuNPs nanocomposite-cysteamine monolayers modified GCE. The optimized parameters were as follows: 90min as the immersion time of SAM modified electrode in the anti-mycelium solution, 0.20 mu g/mL as the concentration of anti-mycelium solution and 10min as the interaction time of immunoreaction. The immunosensors exhibited low limit detection of 309ng/mL and good reproducibility.