Electrochemical Sensor for the Determination of Methotrexate Based on MOF-Derived NiO/Ni@C-Poly(isonicotinic acid)

A new electrochemical sensor based on NiO/Ni@C and poly(isonicotinic acid), PINA, is fabricated to determine an important chemotherapeutic drug, methotrexate (MTX). At first, a bare glassy carbon electrode (GCE) was modified by NiO/Ni@C; then, INA was electropolymerized at its surface. FT-IR, XRD, FE-SEM, EDS, elemental mapping, TEM, AFM, and BET techniques were used to characterize the nanomaterials. Following that, parameters affecting the sensor response, such as pH, amount of the electrocatalyst, electropolymerization cycles, and instrumental parameters, were optimized using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Under the optimized conditions, a linear range was obtained from 0.02 to 2.5 μM with a detection limit of 7.2 nM. Repeatability was obtained with a relative standard deviation (RSD) of 2.4%, and reproducibility was obtained with an RSD of 6.2%. Finally, the sensor was tested in the presence of potential interference compounds and human blood plasma with acceptable responses.