Study of antibacterial and cytotoxic properties of copper nanoparticles obtained through a novel approach

Zero-valent copper nanoparticles (Cu⁰NPs) possess notable properties such as electrical conductivity, catalytic activity, and antimicrobial effects, making them attractive. Their synthesis remains challenging due to their high oxidation tendency. In this study, CuNPs were synthesized in aqueous medium under ambient conditions and characterized by UV-Vis spectroscopy, X-ray diffraction (XRD), and transmission electron microscopy (TEM). Antibacterial, reactive oxygen species (ROS), and cell viability assays were performed. The nanoparticles exhibited a maximum absorption peak at 595 nm, a crystalline structure without detectable impurities, and quasi-spherical morphology ranging from 2 to 47 nm. These characterization analyses suggest the obtention of Cu0NPs. Antimicrobial activity against Staphylococcus aureus, Escherichia coli, and Enterococcus faecalis, exhibited a minimum inhibitory concentration of 100 µg/mL, with inhibition rates of 99.85%, 99.94%, and 99.77%, respectively. ROS assays indicated that oxidative stress may contribute to bacterial death. Cell viability assays revealed a dose-dependent cytotoxic effect on the cells tested (Human Gingival Fibroblasts, Human Bone Cells, and Human Periodontal Ligament Cells) with CC₅₀ values around 13–15 µg/mL. The findings from the cell viability assay at effective CuNPs doses underscore the need for cautious interpretation of antibacterial efficacy in relation to cytotoxicity, particularly in the context of biomedical applications.