Integrated Electrochemical and Biomedical Properties of Cu-Doped ZnO NPs Synthesized via Green Methods

A sustainable green synthesis method was utilized to prepare copper-doped zinc oxide (Cu-ZnO) nanoparticles (NPs) using <i>Bixa orellana</i> L. leaf extract as a biogenic reducing and stabilizing agent. The synthesized NPs were characterized by UV-visible spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), confirming their spherical morphology, crystalline structure, and particle sizes ranging from 40 to 52 nm. Electrochemical performance evaluated by cyclic voltammetry (CV) on a glassy carbon electrode (GCE) modified with ZnO and Cu-ZnO NPs showed quasi-reversible redox behavior with an increased peak-to-peak separation (Δ<i>E</i> _p), indicating slower electron transfer. ZnO-modified GCE exhibited a higher current response over a wider potential range, suggesting superior electrocatalytic activity compared to Cu-ZnO NPs. Antibacterial studies demonstrated effective inhibition against Gram-positive (<i>Bacillus subtilis</i>, <i>Enterococcus faecalis</i>, and <i>Staphylococcus aureus</i>) and Gram-negative (<i>Pseudomonas aeruginosa</i> and <i>Escherichia coli</i>) strains. Cytotoxicity assays revealed dose-dependent anticancer effects against PANC-1 cells, and hemolysis tests confirmed hemocompatibility. Antioxidant activity was validated via the DPPH assay. These multifunctional properties highlight the electrocatalytic and biomedical potential of eco-friendly synthesized Cu-ZnO NPs, emphasizing their promise for therapeutic and electrochemical applications, with ZnO showing superior performance in energy storage.