Electrochemical Detection of Ornidazole Using a WS2 /CNFs Sensor
Authors: Barwa Tara N 
Published: August 2024

In recent decades, pharmaceutical compounds, notably antibiotics, have played a significant role in preventing infections and illnesses that affect both animals and humans. However, the utilization of antibiotics in the pharmaceutical industry, farming and other applications has led to environmental concerns 1. Nitroimidazole, an oral drug, is commonly used as an antibacterial agent. An example of a drug in nitroimidazole family is ornidazole (ORZ, (1-(3-chloro-2-hydroxy) propyl-2-methyl- 5-nitroimidazole)), and it is used in treating and preventing various infections, including genitourinary tract, intestinal and protozoal infections. Ornidazole has a heterocyclic structure comprising of an imidazole-based nucleus with a nitro group (NO2)1 and have become a well-established group of antiprotozoan and antibacterial agents. Beyond immediate therapeutic benefits, ornidazole could persist in the environment, posing long-term risks such as potential mutagenic and carcinogenic effects. Moreover, excessive antibiotics such as antibiotics such as ORZ in the environment can lead to the development of antibiotic-resistant pathogens. The widespread use of antibiotics in medical treatment and agriculture contributes to water contamination as these substances find their way into water bodies through various pathways. There is escalating concern over pharmaceutical contaminants therefore highlighting the importance of monitoring and regulating antibiotic levels in the environment. This requires significant research and electrochemical methods portray possibilities for drug detection due to their advantages of high sensitivity, low cost, simplicity and selectivity.
Recent developments have brought to the spotlight, two dimensional materials as promising candidates for environmental sensing, due to their unique characteristics and wide-ranging applications. In particular, Transition-metal dichalcogenides (TMDs), comprising of MX2 , with M a transition metal atom e.g. Mo, W etc. and X, a chalcogen atom S, Se or Te 2, have garnered attention for their exceptional features. These materials consist of M atoms closely sandwiched between two layers of X atoms, linked by strong in-plane covalent bonds, and further bonded by weak van der Waals forces between the layers. Among the TMDs, tungsten disulfide (WS2) exhibits exceptional properties, including high electronic conductivity, good chemical stability, large capacitance and surface area. Those inherent properties of WS2, make it a suitable material for various applications, especially in environmental sensing 3.
This study explores the detection of ornidazole using a composite material of WS2 with functionalized carbon nanofibers (CNFs). Carbon nanofibers (CNFs) are featured for their equally outstanding electrical and mechanical properties that make them promising candidates for sensor applications. CNFs also provide a unique platform for developing sensitive and selective sensors. Their versatility allows for functionalization, enhancing chemical properties and enabling tailored interactions with target analytes. The study emphasizes how CNFs, with their notable properties, complement WS2 in the creation of innovative sensor structures to create composites with improved sensing capabilities for drug compounds. In this study, the WS2/CNF nanocomposite was synthesized using hydrothermal synthesis and subsequently dispersed in ethanol and water, and then drop casted on a glassy carbon electrode. Prior to synthesis, the CNFs were functionalized using a low cost, environmental friendly method, thus enhancing their chemical properties. Herein, the resulting WS2/CNF composite demonstrates its efficacy in detecting ornidazole, and shows excellent potential for the development of electrochemical sensors. Overall, the work here aims to highlight the ongoing progress of electrochemical sensor technology, emphasizing its crucial role in addressing the growing challenges associated with drug contamination in the environment.
References
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