Green synthesis of silver nanoparticles using gesho (Rhamnus prinioides) fruit extract and evaluation of their antibacterial activity

Abstract

Nowadays, the applications of metal nanoparticles are growing rapidly in different fields due to their unique properties such as size and shape. Among these nanomaterials, silver nanoparticles (Ag NPs) are commonly used in many applications due to their unique optical properties, relatively high stability, and strong conjugation ability with biomolecules. Several eco-friendly approaches have been used to synthesize the nanoparticles. Many scientists are focused on green synthesis of nanoparticles from plant extracts. In the context of this, we have investigated the fruit of Rhamnus prinoides L’Herit to make innumerable sources of cost-effective, non-hazardous reducing and stabilizing compounds utilized in preparing Ag NPs. During the synthesis of the nanoparticle, we used 5% (w/v) of 50 mL R. prinoides fruit extract and 3 mM of 50 mL silver nitrate solution. The formation and characterization of Ag NPs were confirmed by UV-Vis spectrophotometry, XRD and FTIR methods. Thus, the formation of a deep red colored solution and the UV-visible absorption peak at 416 nm was taken as an initial confirmation of Ag NPs formation. The result was due to the excitation of the surface plasmon resonance in the Ag NPs. While the FTIR spectroscopic study showed the involvement of R. prinoides fruit extract in the reduction of Ag⁺ ions to Ag NPs. The particle size of the synthesized nanoparticles, in accordance with XRD result, was calculated using Debye Sherrer’s equation and the result was found to be equal to 21 nm. The antibacterial activity of the silver nanoparticles against pathogenic microorganism strains of Escherichia coli and Staphylococcus aureus was confirmed by the disc diffusion method and was found to inhibit the growth of the bacteria with an average zone of inhibition size of 23 mm against E. coli and 13 mm against S. aureus. The results showed that green synthesized Ag NPs exhibited significant antimicrobial potency.