Scientific Reports — Vol. 2 · 2026

Abstract A novel electrochemical sensor based on multi-walled carbon nanotubes doped with vanadium pentoxide/telluride (MWCNTs@V2O5/Te) was developed for the detection and quantification of morphine sulfate in real biological samples. MWCNTs@V2O5/Te nanocomposite was functionalized with cysteamine as a linker, to create thiol interaction with the -OH group of the MWCNTs@V2O5/Te nanocomposite at one end, and free -NH2 group interaction with the -OH group on morphine sulfate, on the other end. This modification enhances the conjugation capability of morphine sulfate with the fabricated biosensor. (MWCNTs@V2O5/Te-Cys/GCE). MWCNTs@V2O5/Te nanocomposite morphological and structural analysis is carried out by SEM, TEM, EDX, FTIR, and UV-Vis spectroscopy. At varying concentrations and pH levels, the electrochemical sensor response of the modified electrode is investigated using cyclic voltammetry (CV). To validate the findings, differential pulse voltammetry (DPV), electrochemical impedance spectroscopy (EIS), and chronoamperometry are employed to investigate morphine sulfate detection, yielding excellent results in real biological samples. The fabricated sensor, as indicated by the calibration curve, exhibits a wide linear range of 10–60 µM and a limit of detection (LOD) of 0.01 µM by DPV. These results reveal that this novel sensor is highly stable, sensitive, and reproducible for detecting morphine sulfate. Therefore, this developed sensing platform can be used in clinical diagnostics, narcotics detection, and forensic analysis.