Glassy carbon electrode modified with 3D graphene–carbon nanotube network for sensitive electrochemical determination of methotrexate

[Display omitted] •A novel 3D graphene–carbon nanotube network was constructed on the surface of glassy carbon electrode through a simple and effective electrodeposition approach.•The prepared 3D interpenetrated graphene-CNT network was successfully used for electrochemical determination of Methotrexate (MTX).•The improved electrochemical performance is ascribed to the large accessible surafce area of the interpenetrated 3DG network as well as its enhanced electrical conductivity by incorporating CNTs.•The proposed method can determine MTX in a wide dynamic linear range with a low detection limit.•The superior properties of the proposed sensing platform make it very suitable for electrochemical determination of MTX in pharmaceutical formulations and clinical preparations. In the present study, a 3D porous graphene-carbon nanotube (G-CNT) network is successfully constructed on the surface of glassy carbon electrode (GCE) by electrochemical co-deposition from a concentrated graphene dispersion. The large accessible surface area provided by the interpenetrated graphene backbone in one hand and the enhanced electrical conductivity of the 3D network by incorporating CNTs on the other hand, dramatically improved the electrochemical performance of GCE in determination of Methotrexate (MTX) as an important electroactive drug compound. Under the optimum conditions, the electrode modification led to a significant increase in the anodic peak current (∼25 times) along with a considerable shift in the peak potential (∼111mV). Voltammetric investigations revealed that the proposed method can determine MTX in a wide dynamic linear range with a low detection limit of 70nM. Moreover, good sensitivity and high accuracy of the prepared modified electrode in voltammetric detections of MTX, which was further confirmed by UV–vis spectroccopy and HPLC methods, make it very suitable for accurate determinations of MTX in pharmaceutical formulations (commercial tablets) and clinical preparations (blood serum) with excellent recoveries.