An electrochemical sensor based on Fe₂O₃ quantum dot-decorated Co₃O₄ nanowires for cannabis detection in food

There is increasing interest in the use of cannabidiol (CBD) as a potential therapeutic for alleviating chronic pain in cancer patients. Reliable determination of CBD content tailored to individual patients is essential for effective administration. Additionally, there is a growing need for rapid and portable detection methods for food products containing trace amounts of cannabis-derived compounds. Electrochemical technique offer a promising approach for fast and straightforward analytical identification of compounds like CBD. This study presents the fabrication of electrochemical sensor utilizing Fe₂O₃ quantum dots (QDs) – Co₃O₄ nanowires (NWs) as a sensing layer in a modified silver electrode. Chemical and structural analyses including energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) analysis, and X-ray photoelectron spectroscopy (XPS) confirm the excellent decoration of Fe₂O₃ QDs on the Co₃O₄ NW surfaces. The Fe₂O₃ QDs-Co₃O₄ NWs exhibit electrochemical activity based on cyclic voltammetry (CV), chronoamperometry (CA), and differential pulse voltammetry (DPV) measurements. The sensor demonstrates a sensitivity of 1.21 mA•mM⁻¹•mm⁻¹ with strong linearity over the range of 0.02–0.1 mM (R² = 0.9991) and a low detection limit of 0.67 µM. The enhanced electrochemical response of the Fe₂O₃ QDs-Co₃O₄ NWs sensing layer is attributed to the increased number of active sites resulting from the heterostructure formed by the two semiconductor crystals. A charge-transfer mechanism driven by stochastic processes is proposed to explain the electrochemical sensing behavior.