▎ 摘　　要

Methotrexate (MTX) anti-Cancer drug is one of the most important drugs widely used in medicine today; however, overuse of this drug causes many side effects, so it is vital to measure it. Therefore, in this work, a straightforward and inexpensive method was designed to produce a sensitive electrochemical sensor based a glassy carbon electrode (GCE) for this drug measurement. The sensor was prepared using graphene quantum dot (GQD), which was synthesized by a green method without using toxic and dangerous substances. Analysis and characterization of the synthesized GQD were performed using different analyzes, and then the modification of the GCE surface was achieved by this GQD. In the second step, gold nanoparticles (AuNPs) and thiol organic compounds were also placed on GQD by electrochemical method. The prepared sensor showed a good application in MTX measurement comparable to and better than previous works. Significant increase in current at the surface of the modified electrode is due to the high surface area, good conductivity, and electrocatalytic activity of these compounds. These improvements were from the synergistic effect of GQD/AuNPs nanocomposite and the catalytic capability of poly thiol organic compound. The detection limit for MTX was in the linear range of 0.1-100 mu M equal to 0.03 mu M. The capability of the prepared sensor was investigated in a real sample.