Green synthesis, characterization, and antimicrobial activity of silver nanoparticles prepared using Trigonella foenum-graecum L. leaves grown in Saudi Arabia

Abstract

Silver nanoparticles (AgNPs) are widely used for medical applications particularly as antimicrobial agents against multidrug-resistant microbial strains. Some plants stimulate the reduction of Ag ions to AgNPs. In this study, we prepared AgNPs via the green synthesis approach using fenugreek leaves grown in Saudi Arabia. Furthermore, we characterized these AgNPs and evaluated their antimicrobial activities against pathogenic yeast, bacteria, and fungi. The ultraviolet-visible peak at 380 nm confirmed the biosynthesis of NPs. Transmission electron microscopy analyses revealed particle size in the range of 9-57 nm with a spherical shape. Dynamic light scattering results confirm slight aggregation as the average particle size was shown as 68.71 nm and a polydispersity index of 0.083. The energy-dispersive X-ray spectroscopy results showed an intense peak at 3 keV, indicating the presence of elemental AgNPs. The synthesized AgNPs efficiently inhibit the growth of both Gram-positive and Gram-negative bacteria; however, varying degree of inhibition was shown toward fungi. The potent antimicrobial ability of the synthesized NPs can be attributed to their small size and round shape. Among all test organisms, the growth of Candida albicans and Helminthosporium sativum was remarkably affected by AgNPs treatment.