Green synthesis of metallic silver and copper nanoparticles from Sesbania aculeata: Structural characterization and comparative biological activities

The synthesis of metallic nanoparticles using plants is an alternative approach to traditional synthesis methods that is environmentally friendly. In this study, silver nanoparticles (AgNPs) and copper nanoparticles (CuNPs) have been synthesized by the green method using extracts of leaves, flowers, and roots of Sesbania aculeata as reducing agents and stabilization agents, as a comparative approach. The synthesized nanoparticles were analyzed by UV–Visible spectroscopy, FE-SEM, FTIR, DLS and Zeta potential analysis. The results of the characterizations revealed differences in particle morphology, hydrodynamic size and colloidal stability depending on the type of plant part. AgNPs and CuNPs made using leaf extract resulted in a comparatively smaller size, and flower- and root-mediated CuNPs showed good surface stability. Biological evaluation revealed that the DPPH and H₂O₂ radical-scavenging activities, as well as the antifungal activity of AgNPs were comparatively higher against Aspergillus niger . In some treatments, the CuNPs exhibited a slightly higher inhibition of the bacteria, but the differences were interpreted descriptively. Smaller amounts of nanoparticles facilitated early seedling growth, while larger amounts had inhibitory effects. For dye-polluted water treatment, AgNPs were more effective at decolourising than CuNPs over the 72-hour period. As a comparative study, two nanoparticles synthesized from three different parts of the plant showed that plant biomolecules have a significant effect on the properties of the nanoparticles and on their functionality. The results suggest that S. aculeata -mediated nanoparticles have potential in biological, agricultural, and environmental applications.