▎ 摘　　要

NOVELTY - Preparing an electrochemical immunosensor comprises modifying the base electrode by graphene oxide hydrogel-methylene blue, where the first antibody solution of the microtubule-related protein light chain 3B is covalently binds to the modified base electrode and obtaining the product. USE - The kit/electrochemical immunosensor is useful for quantitative detection of secreted autophagosomes and detecting tumors (claimed). ADVANTAGE - The method: is economical; and has high sensitivity, good specificity, a wide linear range and low detection limit. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for: (1) electrochemical immune sensor; (2) use method of electrochemical immunosensor comprising (i) adding ferric oxide-aurum secondary antibody nanomagnetic bead solution to autophagosome solution dropwise, reacting at 20-50 degrees C for 10-120 minutes, washing with phosphate-buffered saline solution and resuspending in phosphate-buffered saline, and magnetically capturing autophagosomes, (ii) adding the autophagosomes captured in step (i) to the surface of the base electrode of the electrochemical immunosensor for specific reaction, reacting at 20-50 degrees C for 10-90 minutes, and washing with phosphate-buffered saline solution and drying; and (3) kit comprising the electrochemical immunosensor