Green Synthesis and Characterization of Silver Nanoparticles Using Ocimum Tenuiflorum (Thulasi) Leaf Extract: Morphological Variations and Antibacterial Activity

Abstract

Silver nanoparticles (AgNPs) have garnered significant attention due to their unique electrical, optical, and biological properties, with applications spanning food, medicine, cosmetics, textiles, and water treatment. The growing demand for AgNPs necessitates environmentally friendly synthesis methods. This study focuses on the green synthesis of silver nanoparticles using Ocimum tenuiflorum (Thulasi) leaf extract as a reducing and stabilizing agent. The chemical constituents of Thulasi, such as oleanolic acid, ursolic acid, rosmarinic acid, and eugenol, contribute to its phytomedicinal properties, including antioxidant, antidiabetic, and anticancer activities. Thulasi extracts have been used to synthesize silver nanoflowers (AgNFs) and spherical silver nanoparticles under three deposition conditions: (1) mixing Thulasi extract with silver nitrate at ambient temperature, (2) stirring the mixture at elevated temperatures, and (3) prolonged blending of the extract and silver nitrate solution. The synthesized nanoparticles were characterized using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), selected area electron diffraction (SAED), and UV-Vis spectroscopy to analyze their structural and morphological variations. The study highlights the influence of synthesis conditions on nanoparticle shape, size, and properties, demonstrating the formation of AgNFs and spherical AgNPs. The antibacterial activity of the nanoparticles against pathogens like Staphylococcus aureus and Escherichia coli was further validated. These findings suggest that Thulasi-mediated AgNPs are promising for diverse applications, including antimicrobial agents in healthcare, food preservation, water purification, and beyond. This study underscores the significance of green synthesis in achieving sustainable and efficient nanoparticle production.