Synthesis and validation of ultrasensitive stripping voltammetric sensor based on polypyrrole@ZnO/Fe3O4 core–shell nanostructure for picomolar detection of artesunate and dopamine drugs

Abstract

A stripping voltammetric sensor for ultrasensitive detection of artesunate (ART) and dopamine HCl (DA) has been successfully developed using a Ppy@ZnO/Fe₃O₄ core–shell nanocomposite ([PZM])-modified carbon paste sensor (MCPS). Fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, dynamic light scattering, Brunauer–Emmett–Teller surface area method, and high-resolution transmission electron microscopy were used to characterize the physicochemical properties of the nanomaterials. Noteworthily, the morphology of [PZM] reveals a spherical core–shell nanostructure with an increase in the average diameter range of 20–37.5 nm (specific surface area (SSA) of 28.5 m² g⁻¹ (0.0247 cm³ g⁻¹)) when compared with the average diameter range 7.5–15.7 nm (SSA of 5.43 m² g⁻¹ (0.0111 cm³ g⁻¹)) of ZnO/Fe₃O₄[ZM]. The [PZM] MCPS provided the best electroactive surface area (0.078 cm²) and the least electrocatalytic activity (R_st = 370 Ω). Furthermore, the MCPS showed low detection limits (LODs) of 0.092 pg mL⁻¹ (0.24 pM) and 0.0046 pg mL⁻¹ (0.03 pM) for ART and DA, respectively. Moreover, LODs were found to be 0.029 pg mL⁻¹ (0.75 pM) and 0.014 pg mL⁻¹ (0.09 pM) for ART mixed with 0.7 pM of DA (ART₁) and DA in the presence of 2.0 pM of ART drug (DA₁), respectively. In addition, the MCPS revealed a proper repeatability, reproducibility, and storage stability (93.5–90.48%). During the routine analysis, the [PZM] MCPS detected ART and DA concentrations in human urine, without interference.