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 [Zn_1−xCu_xO 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 revealed a blueshift at lower concentrations of Cu doping (ZCu2 and ZCu4) attributed to the Burstein–Moss effect and a redshift at higher concentrations of Cu doping (ZCu6) due to defect-induced band gap narrowing, enhancing visible-light absorption. Photoluminescence analysis revealed band-edge emissions (409–430 nm) with optical band gap widening (3.30–3.47 eV) and defect-related emissions at higher Cu content. Zeta potential measurements indicated improved colloidal stability of the 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.