N. Salandari-Jolge & Ali A. Ensafi & Behzad Rezaei

Abstract
Considering the importance of measuring anticancer drugs, a carbon paste electrode (CPE) modified with CuCr2O4/CuO nanofibers in the presence of hydrophobic ionic liquid (IL) was fabricated for methotrexate (MTX) sensing. CuCr2O4/CuO nanofibers were prepared by electrospinning method. Then, the morphology and structure of the nanofibers were studied by scanning electron microscopy, thermal analysis, X-ray diffraction, energy-dispersive X-ray, map analysis, and FT-IR spectroscopy.
The electrochemical behavior of MTX at CuCr2O4/CuO/IL/CPE surface was studied using cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy. After optimization of the experimental parameters, the prepared sensor showed a low detection limit of 25 nM MTX, based on signal-to-noise (S/N = 3), and it can determine in a wide range of 0.1–300 μM in Britton-Robinson buffer solution at pH 2.5. The modified electrode was used to determine MTX concentration in blood and urine samples with good recoveries of 94.1–104.3. This sensor has several advantages such as low cost, easy preparation, high-performance speed and high sensitivity, selectivity, stability, and repeatability.

Keywords Copper chromite . Nanofibers . Electrospinning . Methotrexate sensor . Voltammetry