WO3/Cu-doped Eggshell-Derived CaO Nanocomposite for Ultrasensitive Electrochemical Detection of Epinephrine

This study offers a novel and sustainable approach to waste reuse and environmental remediation via the synthesis of calcium oxide (CaO) nanoparticles doped with tungsten oxide and copper (WO3/Cu) from the food waste eggshells for ultrasensitive electrochemical detection of epinephrine (EPI). EPI is also known as adrenaline, is a medication and hormone. Biowaste eggshell-derived CaO, obtained through calcination, serves as a sustainable support matrix for WO3 and Cu, enhancing its porous hierarchical structure to prevent particle agglomeration and increase active sites. The nanocomposite was analyzed using various techniques including fourier-transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy, transmission electron microscopy, atomic force microscopy, and Raman spectroscopy. The WO3/Cu:CaO was blended homogeneously with carbon paste electrode (CPE) for the sensitive detection and quantification of EPI in pH 7.4 phosphate buffer saline (PBS). The charge transfer resistance and other electrochemical impedance spectroscopy data of bare and modified CPE were used for identifying the efficiency of the fabricated electrode. Electrochemical studies evidenced a detection limit of 0.00246 mu M (S/N = 3) with a linearity range 0.1-1000 mu M. In the presence of metal ions and interfering excipients, the synthesised sensor's selectivity was examined. The real-sample analysis of human serum, urine, and breast milk achieved 98-99 % recovery values. The good recovery values, excellent reproducibility make WO3/Cu:CaO/CPE a suitable for analytical tool for non-enzymatic EPI detection at the nanolevel. The WO3/Cu:CaO nanocomposite modified CPE holds significant promise for future development of portable, low-cost, point-of-care devices to repurpose into high-performance sensing materials for rapid detection of EPI in biomedical field.