Green synthesis of copper oxide nanoparticles with Calendula officinalis plant extract and investigation of its toxicity

In this study, copper oxide nanoparticles (CuO-NPs) were synthesized using a green, eco-friendly method employing the ethanolic extract of Calendula officinalis. The synthesis leveraged the plant’s rich phytochemical profile to act as both reducing and capping agents, resulting in nanoparticles with enhanced biocompatibility and stability. The CuO-NPs were characterized using UV–Vis spectroscopy, FT-IR, X-ray diffraction (XRD), dynamic light scattering (DLS), and Atomic Force Microscopy (AFM), confirming their formation, functional groups, crystalline structure, and nanoscale dimensions. The average particle size was ~ 6.66 nm, with a negative zeta potential indicating good colloidal stability. Hemocompatibility and cytotoxicity were evaluated via hemolysis and MTT assays on normal HFF-2 human fibroblast cells. Results showed less than 5% hemolysis and relatively low cytotoxicity compared to chemically synthesized counterparts, highlighting the safety of the green synthesis method. This study demonstrates the potential of-mediated CuO-NPs as promising candidates for biomedical applications Calendula officinalis such as drug delivery and cancer therapy.