▎ 摘　　要

Background: Sulfamethoxazole (SMX) can produce many side effects in the human body and several hematological abnormalities. Therefore, the analytical determination of SMX in pharmaceutical formulations and biological fluids is essential. Methods: A biocompatible composite of graphene oxide/graphene (GO/G) layered structure was synthesized to develop electrochemical biosensors for SMX detection. Two layers of single-layer graphene grown by chemical vapor deposition were stacked and annealed to form bilayer graphene (BLG). The BLG was modified by a low-damage plasma treatment-atomic layer oxidation. The top graphene layer was modified to graphene oxide, while the bottom graphene layer was conserved to safeguard its conductive properties and form a layered composite on an indium tin oxide (ITO) substrate. Significant findings: The GO/G layered composite on the ITO glass substrate, plasma-treated for 15 min exhibited optimized redox properties, with a relatively low charge-transfer resistance. At pH 6, the relationship between the oxidation peak current and the SMX concentration (0.1-50 mu M) was linear with a sensitivity of 0.262 mu A/mu M. With the addition of cetylpyridinium chloride, the sensing performance of the GO/G-based electrochemical sensor was ameliorated to 0.529 mu A/mu M. The GO/G electrode also exhibited high selectivity and stability to SMX. (C) 2021 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.