Synergistic Enhancement of Physicochemical and Biomedical Properties in Microwave-Synthesized Copper-Doped Zinc Oxide Nanoparticles

Abstract

Copper (Cu) doping in zinc oxide (ZnO) nanoparticles (NPs) is known to enhance their functional properties, making them attractive for biomedical applications. In this study, Cu-doped ZnO NPs [Zn₁₋ₓCuₓO with x = 0.0385 (ZCu2), 0.08 (ZCu4), and 0.115 (ZCu6)] were synthesized using a microwave-assisted combustion route and comprehensively characterized. X-ray diffraction confirmed single-phase wurtzite ZnO with Cu incorporation, with crystallite sizes ranging from 54.65 to 71.66 nm and associated variations in strain and dislocation density. SEM analysis revealed particle sizes of 122–197 nm, in agreement with XRD results, while FTIR confirmed Zn–O vibrational shifts due to Cu substitution. UV–Vis absorption spectra exhibited a blue shift at lower Cu doping (ZCu2, ZCu4) attributed to the Burstein–Moss effect and a red shift at higher doping (ZCu6) due to defect-induced band gap narrowing, enhancing visible-light absorption. Photoluminescence analysis revealed band-edge emissions (409–430 nm) with optical bandgap widening (3.30–3.47 eV) and defect-related emissions at higher Cu content. Zeta potential measurements indicated improved colloidal stability for doped samples. Biomedical assays demonstrated notable antibacterial, antifungal, antioxidant, hemocompatible, and anticancer activity against MDA-MB-231 breast cancer cells. These findings establish Cu-doped ZnO NPs as promising candidates for nanomedicine applications.