Sensitive and rapid detection of methotrexate in serum and saliva with MWCNT and STAC modified acetylene black paste electrode

A novel electrochemical sensor of multi-walled carbon nanotube (MWCNT) and stearyl trimethyl ammonium chloride (STAC) modified acetylene black paste electrode (AB-PE) was successfully established. An AB/MWCNT/STAC-paste electrode was constructed using the AB electrode with MWCNT and STAC as the electrochemical sensor materials. The performance of the prepared sensor was characterized by electrochemical impedance spectroscopy and cyclic voltammetry. Some factors, such as sensor composition, adsorption, and detection conditions, which affect the property of the sensor, were investigated in detail. The results demonstrated that the prepared sensor has satisfactory selectivity, repeatability, and stability for methotrexate (MTX) detection. The linear range of the method for MTX detection was 0.02–8.0 μM with a limit of detection (LOD) of 1.81 nM. Finally, the sensor was successfully used for detecting the MTX concentrations in the samples of serum and saliva. The prepared sensor could be a fresh platform for the swift and accurate MTX detection in clinical samples. Graphical abstract