Synthesis and characterization of lemon leaf extract-mediated silver nanoparticles: An environmentally friendly approach with enhanced antibacterial efficacy

Abstract

In this study, silver nanoparticles were synthesized using lemon leaf extract, which served as both a reducing and stabilizing agent. The synthesis process proved to be rapid, cost-effective, and environmentally friendly. The effect of the mixing ratio of the reactants was investigated. Optimal yield, approximately 70 %, was achieved at 60 °C with a 0.25 M silver nitrate solution interacting for 40 min with lemon leaf extract in a 1:1 (v/v) ratio. Confirmation of nanoparticle formation was achieved through visible color change, UV–visible spectra (UV–Vis), X-ray diffraction analysis (XRD), Fourier transform infrared spectra (FT-IR), zeta potential, scanning electron microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX), and transmission electron microscopy (TEM). The UV–Vis spectrum of the aqueous medium containing silver nanoparticles showed an absorption peak at around 412 nm. FT-IR spectra had shown that the biomolecule compounds were responsible for the reduction and capping material of silver nanoparticles. The XRD study showed the particles displayed an average crystallite size ranging from 9.4 to 36 nm. SEM and TEM showed a face-centered cubic (FCC) structure with an average size of 34 nm. The stability was detected using zeta potential analysis. These nanoparticles were used as antibacterial agents against Escherichia coli and Methicillin-resistant Staphylococcus aureus (MRSA), and the effect of silver nanoparticle concentration was investigated. The results indicated the synthesized silver nanoparticles demonstrated significant antibacterial activity against E. coli and MRSA, with average inhibition zone diameters exceeding 17 mm for E. coli and 15 mm for MRSA. Remarkably, antimicrobial activity was observed against two tested microbes at extremely low concentrations of 1–3 mM of silver nanoparticles.