Eco-Friendly Synthesis and Characterization of Senna italica-Derived Silver Nanoparticles With Broad-Spectrum Antimicrobial Activity.

Abstract

The eco-friendly and cost-effective biological synthesis of nanomaterials is rapidly gaining attention. This study synthesized silver nanoparticles (AgNPs) using an aqueous extract of Senna italica leaves and silver nitrate (AgNO₃). The synthesized AgNPs were characterized using UV-Vis spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray diffraction (XRD). UV-Vis spectroscopy confirmed the formation of AgNPs, displaying a characteristic surface plasmon resonance peak at 445 nm. TEM and SEM analyses revealed spherical nanoparticles with sizes ranging from 12.7 to 24 nm. FTIR spectra identified bands at 1636 and 3496 cm^-1, corresponding to C=O and O-H groups, indicating their role in stabilizing the nanoparticles. XRD analysis revealed diffraction planes at 111, 200, 220, and 311, consistent with the face-centered cubic structure of silver. The AgNPs demonstrated significant antimicrobial activity against fungi and Gram-negative and Gram-positive bacteria, with Escherichia coli showing the highest sensitivity (MIC = 0.014  μg/mL). SEM analysis of E. coli showed that untreated cells retained their normal morphology, whereas AgNP-treated cells appeared shriveled and deformed. These results underscore the potential of Senna italica-derived AgNPs as effective antimicrobial agents. Future studies will be aimed at investigating the detailed mechanisms underlying the effects of AgNPs on bacterial cell structure and growth.