Harnessing the phytochemical potential of Kalanchoe fedtschenkoi to synthesize CuO nanoparticles with multifaceted bioactivities

Synthesis of metal oxide nanoparticles using phytochemicals offers a safer and more sustainable alternative to conventional chemical methods. In this work, an eco-friendly and efficient approach was developed for synthesizing copper oxide nanoparticles ( Kf- CuONPs) using Kalanchoe fedtschenkoi leaf extract as a natural reducing and stabilizing agent. The synthesis conditions were standardized at pH 9, 70 °C and 1 mM copper precursor, and these parameters produced a distinct absorption peak at 355 nm, confirming nanoparticle formation. FESEM images showed nearly spherical particles with an average size of ∼24 nm, while TEM analysis revealed particles ranging from 10 to 45 nm with mild aggregation. XRD confirmed monoclinic crystalline CuO with characteristic diffraction peaks and an average crystallite size of ∼24 nm. FTIR spectra indicated the presence of O–H, C–H, C O and Cu–O vibrations, suggesting active participation of plant phytochemicals. DLS recorded a hydrodynamic diameter of ∼37 nm. GC–MS profiling detected major compounds such as citronellal, γ-terpinene, linalool and humulene, supporting their involvement in reduction and capping. The nanoparticles exhibited broad biological activity, including inhibition of Staphylococcus aureus , Escherichia coli and Candida albicans , strong antioxidant and antidiabetic responses (IC₅₀: 89.7 and 84.54 µg/mL respectively), anti-inflammatory potential (IC₅₀: 98.72 µg/mL) and anticancer activity against MCF-7 and A549 cells (IC₅₀: 30.68 and 92.03 µg/mL respectively). These findings demonstrate that K. fedtschenkoi is a promising source for the green synthesis of nanomaterials, and future studies may explore scale-up strategies and mechanistic insights to support potential biomedical and environmental applications.