Potential-dependent real-time multidrug sensing with screen printed manganese oxide electrode platform

Abstract

Emerging pollutants (EPs) provide a new global water quality concern, potentially posing a major damage to human health and the surrounding. Pharmaceuticals, extensively used in both human and veterinary medicine, have become pervasive environmental contaminants due to their continual release into sewage systems and subsequent ubiquity in various ecosystems. In the ambient matrix, they are often present in small amounts (ng/L to g/L) due to their stable composition and slightly elevated polarization. Traditional methods for detecting pharmaceutical compounds in water have long been hindered by their expense and complexity, making widespread implementation challenging. However, electrochemical sensors offer a promising solution to this problem. These sensors provide a cost-effective, portable, and user-friendly alternative to traditional analytical techniques. This research focuses on the development an electrochemical sensor using a screen-printed manganese oxide electrode platform for the potential-dependent analysis of multiple drugs, including sulfamethoxazole, carbamazepine, metoprolol, and ibuprofen. These substances are critical to monitor due to their widespread presence and potential health implications. The study leveraged the unique properties of MnO2 nanoparticles, such as their electrochemical activity, large surface area, and catalytic qualities, to enhance the sensitivity and functionality of screen-printed electrodes for the detection of these drugs. The MnO2 nanoparticles were characterized using a suite of techniques including Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible spectroscopy, small-angle X-ray scattering (SAXS), and Raman spectroscopy. The optical properties of MnO2NPs were investigated using UV/Vis spectroscopy, covering a wavelength range from 280 to 800 nm. This analysis revealed crucial information about the behaviour of MnO2NPs in response to light across different wavelengths. Specifically, the band gap of the MnO2NPs was determined to be 1.14 electron volts (eV) suggests that these nanoparticles possess favourable electrical and optical characteristics. A band gap of this magnitude indicates that MnO2NPs can effectively absorb light within a certain energy range, making them potentially useful in various applications such as photocatalysis, photovoltaics, and optical sensing. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were employed to investigate the electrochemical behavior of both bare and MnO2NPs-modified screen-printed electrodes. A comparison between the two revealed significant differences in electron transfer kinetics. In the case of the bare electrode, EIS and CV analyses indicated slower electron transfer kinetics, as evidenced by a peak potential separation of 0.249 V in the CV curve. This separation reflects the energy barrier that electrons must overcome during the redox process. Conversely, for the MnO2NPs-modified SPCE, the peak potential dispersion was reduced to 0.269 V, suggesting faster electron transfer kinetics. This reduction in peak potential separation indicates a more efficient and rapid reaction occurring at the electrode surface, likely facilitated by the presence of MnO2NPs. The study investigated the influence of pH, scan speed, and electrolytes to identify optimal experimental conditions. Subsequently, under these ideal circumstances, the electrochemical characteristics of carbamazepine, sulfamethoxazole, ibuprofen, and metoprolol were assessed using differential pulse voltammetry. Calibration curves were constructed for each analyte of interest, enabling the determination of limit of detection. The results revealed limit of detection 0.0005 μM for CBZ, 0.0002 μM for SMX, 0.0004 μM for IBU, and 0.005 μM for MP. These values were derived from the extrapolation of calibration curves, which demonstrated linearity within the range of 0.010 to 0.006 μM. These limits of detection signify the lowest concentrations of each analyte that can be reliably detected and quantified using the DPV technique under the specified experimental conditions. Furthermore, the study conducted stability and interference investigations to evaluate the performance of the MnO2NPs/SPCE sensor under optimal conditions. These investigations demonstrated satisfactory performance, indicating the sensor's robustness and reliability in real-world applications. The effectiveness of the suggested sensor was validated through its successful application in analysing wastewater samples. This practical testing confirmed the sensor's ability to detect multiple drugs, highlighting its potential accurately and selectively. In conclusion, the study successfully developed an extremely accurate, precise, and selective MnO2NPs/SPCE sensor for the multidrug detection. By combining the advantages of MnO2 nanoparticles and screen-printed electrode technology, this sensor offers a cost-effective and efficient solution for environmental monitoring and pharmaceutical analysis.