Innovative Architecture of a Multi-Walled Carbon Nanotube-Nickel Tungstate-Integrated Screen-Printed Carbon Electrode for Ofloxacin Detection in Human Samples

Ofloxacin (OFL) residues are a widely used antibiotic for animals, but their contamination of water poses serious risks to the environment and human health. Therefore, its sensitive and selective electrochemical detection is more crucial. In this study, a selective OFL sensor was fabricated by Multi-Walled Carbon Nanotubes (MWCNT) combined with hydrothermally prepared Nickel Tungstate (NiWO₄) to form an MWCNT@NiWO₄ composite. After that, the MWCNT@NiWO₄ composite is coated on the screen-printed carbon electrode (SPCE) or forms SPCE/MWCNT@NiWO₄ electrode. The SPCE/MWCNT@NiWO₄ electrode exhibits a significantly enhanced electrochemical response for ofloxacin compared to the weak signal observed at the unmodified SPCE. Additionally, the electrochemical analysis of OFL in actual human samples was performed using the SPCE/MWCNT@NiWO₄ electrode. The crystallinity and morphology of the composite were characterized by field emission scanning electron microscopy, X-ray diffraction, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, Brunauer-Emmette-Teller method, elemental mapping analysis, and Fourier Transform Infrared Spectroscopy. Electrocatalytic performance and electrochemical characterizations were evaluated using cyclic voltammetry, differential pulse voltammetry, electrochemical impedance spectrum, linear sweep voltammetry, and Chronoamperometry. Under optimal conditions, the electrode demonstrated excellent electrochemical performance towards the OFL sensor with a sensitivity (Sensitivity = Slope/Active surface area (cm²)) of 1.92 µA µM⁻¹ cm⁻², a low limit of detection (S/N = 3) of 0.01 µM, and long linear detection of 0.1 to 120 µM. The electrode also showed excellent repeatability, selectivity, reproducibility, anti-interference, and stability. Stability evaluations demonstrate consistent performance over the 100th cycle. Compared to the conventional HPLC method, the developed electrochemical sensing approach offers advantages such as eco-friendliness, reduced detection time, simplicity, sensitivity, convenience, and cost-effectiveness. The sensor exhibits excellent stability, reusability, and resistance to interference from commonly present excipients in pharmaceutical formulations. The sensor demonstrated excellent selectivity, strong stability, and satisfactory reproducibility in OFL detection. This study presents a low-cost, rapid, and straightforward electrochemical sensor for the sensitive detection of OFL in human blood serum and urine samples, which demonstrates high precision and accuracy. This study provides valuable insights into the use of electrochemical sensors, paving the way for advancements in food safety and environmental protection.