Synthesis of biogenic silver and gold nanoparticles from Anemopsis californica extract with antibacterial and cytotoxic activities

Abstract

Silver (Ag) and gold (Au) nanoparticles, have gained attention for their unique properties and diverse applications, including medicine and antimicrobial agents. To meet the demand for eco-friendly synthesis methods, we explored plant-mediated nanoparticle synthesis using Anemopsis californica extracts. The Anemopsis californica leaves were used to extract bioactive compounds with water, methanol, and isopropanol. These extracts served as reducing and stabilizing agents for Ag and Au nanoparticle synthesis. The process involved mixing the extract, a metallic precursor solution, and deionized water in specific volume ratios, resulting in nanoparticles denoted as W-(Ag or Au), M-(Ag or Au), and I-(Ag or Au) for water, methanol, and isopropanol, respectively. The synthesized nanoparticles ranged from 5 to 30 nm in size and displayed various shapes. UV-Vis spectroscopy confirmed their presence with surface plasmon resonance bands. Antibacterial tests on Staphylococcus aureus and Escherichia coli showed significant antibacterial effects of Ag nanoparticles, especially those synthesized in methanol. In contrast, Au nanoparticles had limited antibacterial impact, regardless of the solvent. Cytotoxicity evaluations with macrophage cells indicated that Ag nanoparticles were more cytotoxic than Au nanoparticles, with the synthesis solvent influencing cytotoxicity. The observed antibacterial effects of Ag nanoparticles align with their reputation as potent antimicrobial agents, particularly against Gram-positive strains. The limited antibacterial impact of Au nanoparticles suggests differences in their antibacterial mechanisms. Varying cytotoxicity between Ag and Au nanoparticles underscores the significance of the chosen synthesis method in shaping nanoparticle properties.