An electrochemical platform for the selective detection of azathioprine utilizing a screen-printed carbon electrode modified with manganese oxide/reduced graphene oxide

Abstract

The long-term use of the immunosuppressive drug, azathioprine (AZT), has been linked to a higher risk of certain cancers; hence, its effective detection is necessary. Recently, the use of transition metal/metal oxide-based materials has attracted intense interest in the field of electrochemistry in combination with carbon materials. Here, we fabricate and demonstrate the use of manganese oxide nanoparticle-decorated reduced graphene oxide modified screen-printed carbon electrodes (Mn₂O₃–rGO/SPCE) for the electrochemical determination of AZT. The structural, functional, and morphological characteristics of the composite material were evaluated using various analytical tools. The crystalline structure of the synthesized Mn₂O₃ nanoparticles is identified as orthorhombic with a crystallite size of 20 nm. The existence of sphere-shaped nanoparticles on the rGO sheets and the component elements are confirmed using field emission scanning electron microscopy (FESEM) and energy dispersive X-ray analysis (EDAX). The fabricated electrode (Mn₂O₃–rGO/SPCE) possesses high electrical conductance, as proved by electrochemical impedance spectroscopy, with an R_ct value of 90 Ω. When compared with other electrodes, the Mn₂O₃–rGO/SPCE has a higher conductive behavior with a wide surface area and a boosted electron transfer, which in turn promotes the effective sensing of AZT. Differential pulsed voltammetry studies (DPV) revealed that the modified electrode possesses a lower limit of detection of about 4 nM, and a sensitivity of almost 7.7 μA μM⁻¹ cm⁻², evaluated for a linear range from 0.009 μM to 573.5 μM. Repeatability and reproducibility studies exhibited a relative standard deviation (RSD) value of about 4.96% and 4.89%. Selectivity studies proved that the proposed sensor showed good selective detection in the presence of relevant interfering compounds. The fabricated Mn₂O₃–rGO modified SPCE would be an efficient sensor for real-time sensing of AZT because of its effective performance with human blood serum and urine samples.