Synthesis of the decorated carbon nano onions with aminated MCM-41/Fe3O4 NPs: Morphology and electrochemical sensing performance for methotrexate analysis

Methotrexate is one of the commonly used drugs in rheumatology; however, its therapeutic effect has many side effects, so its measurement is crucial. Therefore, a versatile modified electrode based on carbon nano-onion (CNO) and iron oxide nanoparticles functionalized with MCM-41-NH2 was prepared to measure this drug in biological samples. Characterization of the synthesized CNO, functionalized iron oxide nanoparticles, and modified glassy carbon electrodes and their electrochemical performance were studied by infrared spectroscopy, scanning electron microscopy, and X-ray diffraction, electrochemical impedance spectroscopy, and voltammetry techniques. The improvement of the methotrexate oxidation current by modified electrode originated from the increased electrode surface area (0.07 cm2). The detection limit and concentration range of methotrexate measurement were 3 nM, and 0.01–50 μM, respectively. The prepared sensor showed good stability and selectivity for methotrexate measurement in the real samples.