▎ 摘　　要

NOVELTY - Preparing a label-free electrochemical immunosensor, comprises: mixing graphene oxide, L-cysteine and boric acid, adding deionized water to disperse, and adjusting the pH, performing a hydrothermal reaction, cooling, washing and drying to obtain boron, sulfur and nitrogen co-doped reduced graphene oxide; heating chloroauric acid solution, adding sodium citrate solution for reflux reaction to obtain a wine red solution, cooling to obtain a gold nanoparticle solution; dispersing reduced graphene oxide in the gold nanoparticle solution, washing and drying to obtain Au-B,S,NrGO-nanocomposite; adding into EDC and NHS solution for activation to obtain a suspension; applying the suspension on the surface of glassy carbon electrode, drying to obtain Au-B,S,N-rGO electrode; dropping an antibody solution onto the surface of the electrode, adding bovine serum albumin for washing to obtain Au-B,S,N-rGO/Ab electrode; incubating the antigen solution on the surface of electrode. USE - The method is usefu for preparing a label-free electrochemical immunosensor. ADVANTAGE - The electrochemical immune sensor has low measuring limit, high sensitivity and high specificity. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for label-free electrochemical immunosensor.