Fabrication of electrochemical sensors using manganese oxide nanostructure- and cobalt oxide nanostructure-decorated ytterbium nanorods as electrocatalysts for the detection of flutamide, bicalutamide and hydroxyflutamide in spiked samples

Abstract

Anti-androgens (AAs) are a class of pharmaceutical drugs used to treat prostate cancer. Over the years, prostate cancer has been reported as the most frequent cancer diagnosis in men and the leading cause of mortality worldwide. However, recent studies show that deaths related to prostate cancer have reduced due to new cancer therapies, including AAs. Consequently, the number of patients using AAs is increasing exponentially. The unremitting use of these AAs may lead to regular excretion in the urine and faeces, thus entering wastewater treatment plants (WWTPs). Since some of these compounds are not entirely eliminated by wastewater treatment plant processes, trace levels remain in inadequately treated sewage effluents and are discharged into surface waters. The discharge might cause continued consumption by people who use surface water for survival, thus causing problems such as drug resistance. Consequently, there is a need to develop methods to determine and control AAs in water. Several analytical methods have been employed. However, the employed methods suffer drawbacks such as high-cost, time consumption and tedious protocols. It is, therefore, of uttermost importance to develop alternative methods to monitor and quantify AAs in water bodies. The AAs of interest in this study are flutamide (FLU), bicalutamide (BIC) and hydroxyflutamide (OHF). In this work, I have developed five electrochemical sensors based on manganese oxide (MnO) and cobalt oxide (CoO) nanostructures (NSs); ytterbium nanorods (YbNRs); as well as YbNRs decorated with MnONSs and CoONSs (YbNRs/MnONSs and YbNRs/CoONSs) as electrocatalysts. This study was conducted in compliance with the University’s Policy on Research Ethics and within the confines of the conditions stipulated in the acquired ethical clearance certificate. The electrocatalysts were synthesised using the hydrothermal and precipitation methods. The as-prepared materials were characterised using Scanning Electron Microscopy (SEM), Fourier Transform Infrared (FTIR) spectroscopy, Ultraviolet-Visible spectroscopy (UV-Vis), Transmission Electron microscopy (TEM), Energy-dispersive X-ray spectroscopy (EDX), and X-ray powder diffraction (XRD). The electrochemical techniques employed in this study are Cyclic Voltammetry (CV) and Square Wave Voltammetry (SWV). The electrochemical responses of the fabricated sensors were examined at a linear range from 32.01 – 50.00 μM. The limit of detections (LODs) and quantifications (LOQs) of the fabricated sensors were comparable to the literature. Both fabricated sensors showed good percentage recoveries. The fabricated electrochemical sensors showed good selectivity, stability, reliability, repeatability and reproducibility. Thus, it can be concluded that the fabricated sensors may represent a simple, low-cost and comfortable electrochemical tool for routine analysis in pharmaceutical and environmental monitoring of contaminants.