▎ 摘　　要

NOVELTY - Method comprises (1) preparing carboxylated graphene quantum dot (GQDs-COOH) by hydrothermal synthesis, slowly adding ultra-pure water into flask, precipitating solution, removing precipitate, concentrating the solution, freezing and drying; (2) preparing polyethylene glycol graphene quantum dot (GQDs-PEG) by incubating activated GQDs-COOH, purifying by ultra-filtration centrifuge tube and concentrating; (3) synthesizing aptamer graphene quantum dot (GQDs-PEG-Apt); (4) preparing molybdenum disulfide nano sheet (WS2) using hydrothermal method; (5) preparing ferroferric oxide nano particles by using solvent thermal method; (6) assembling molybdenum disulfide/ferroferric oxide nano-composite; (7) constructing aptamer graphene quantum dot/molybdenum disulfide/ferroferric oxide magnetic separation fluorescence enhancement type aptamer sensing system; and (8) quantitative detecting tumor marker CA19-9 by using magnetic separation fluorescence enhanced aptamer sensor. USE - The method is useful for detecting tumor marker CA19-9 by magnetic separation fluorescence enhanced aptamer sensor. ADVANTAGE - The method has good specificity, high sensitivity, wide detection range, low detection limit, low cost, simple operation, and good practical value.