Eco-Friendly Synthesis of Copper Oxide Nanoparticles Using Geranium Pelargonium x hortorum Leaf Extract and Its Biological Applications.

Background/Objectives: The main objective of this study is to report the green synthesis of copper oxide nanoparticles (CuONPs) using an aqueous extract from Pelargonium x hortorum (P. hortorum) leaves. It also aims to evaluate its biological activity as well as assess its cytotoxic effects on human gingival fibroblasts (HGFs). Methods: Copper oxide nanoparticles (CuONPs) were synthesized through chemical precipitation using an aqueous extract from P. hortorum leaves. These CuONPs were characterized with various techniques, including UV-Vis, Fourier transform infrared (FT-IR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). Results: The UV-Vis spectrum showed a characteristic absorption peak for CuONPs. FT-IR spectroscopy identified alkoxide and aromatic groups associated with flavonoids and phenolic compounds from P. hortorum. The Cu-O bond was also observed in the same analysis. XRD confirmed that the CuONPs had a monoclinic CuO structure and XPS revealed copper was in the Cu (II) oxidation state bonded to oxygen, consistent with CuO. The nanoparticles were spherical with an average size of 40-53 nm as shown by TEM. The biological activities of CuONPs were tested against Streptococcus mutans (S. mutans) and Candida albicans (C. albicans). The minimum inhibitory concentration (MIC) was 20 µg/mL. Cytotoxicity tests on human gingival fibroblasts (HGFs) after 24 h showed a non-linear, dose-dependent cell viability profile, indicating CuONPs did not exhibit cytotoxicity within the tested range and could even promote cell proliferation at low and intermediate concentrations. Conclusions: This study successfully synthesized CuONPs via a green method, highlighting its potential as a biocompatible antimicrobial and antifungal agent.