Electrokinetic assessment of Azelnidipine using Annona squamosa plant extract-derived Co3O4-ZnO nanocomposite fabricated pencil graphite electrode.

Herein, an advanced and highly selective voltammetric sensor based on a low-cost, disposable pencil graphite electrode decorated with a cobalt oxide-zinc oxide nanocomposite (Co3O4-ZnO@PGE) is proposed for the quantification and electrokinetic studies of the vasodilator drug azelnidipine (AZD). The cobalt oxide-zinc oxide (Co3O4-ZnO) nanocomposite was synthesized using Annona squamosa leaf extract, highlighting the potential to synthesize nanoparticles from biomass waste. The crystalline nature and spherical and rod-shaped core-shell microstructure of the Co3O4-ZnO nanocomposite were confirmed by field-emission scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, Raman analysis, and X-ray photoelectron spectroscopy. The electrokinetic investigations of azelnidipine were performed using cyclic voltammetry (CV), square wave stripping voltammetry (SWSV), and chronocoulometry. The voltammograms showed a single peak due to the electrochemical reduction of AZD at Co3O4-ZnO@PGE, which was used to study the electrokinetic behavior of AZD. The electron transfer coefficient (α = 0.514), diffusion coefficient (Do = 3.49 × 10-7 cm2 s-1), and surface coverage (Γo = 4.372 × 10-10 mol cm-2) were evaluated, and the mechanism governing electrochemical reduction of AZD was also proposed. Moreover, an advanced SWSV method was introduced for the selective, sensitive, and precise sensing of AZD using the fabricated Co3O4-ZnO@PGE probe. The calculated limit of detection (LOD) and limit of quantification (LOQ) for the SWSV method were 1.17 µM and 3.92 µM, respectively, making it a useful technique for low-cost and eco-friendly detection of AZD in pharmaceutical samples. The green-synthesized Co3O4-ZnO nanocomposites also exhibited very good antioxidant and antidiabetic properties.