Antibacterial and Antifungal Activity of Green-synthesized Silver Nanoparticles Using Spinacia oleracea leaves Extract

Abstract

In this study, silver nanoparticles (AgNPs) were green synthesized using aqueous leaf extracts of green spinach that have been used as antimicrobial agents. The antimicrobial efficacy was evaluated against bacterial and fungal strains. The morphological structures, optical and surface properties of as-synthesized nanoparticles have been investigated via a Transmission electron microscope, X-ray diffraction, UV-Vis absorption, and Fourier transform infrared, respectively. The colloidal stability was evaluated using dynamic light scattering and zeta-potential measurements. The average size of as-synthesized particles was about 15±5nm. The green synthesized AgNPs showed significant antibacterial activity against different bacterial species via the agar well diffusion assay. The inhibition zones were varied from 27 to 34mm against 6 bacterial species (K. pneumoniae, E.coli, A. baumannii, P. aeruginosa, S. aureus, and S. haemolyticus). In such a case, the minimal inhibition concertation of AgNPs against bacterial isolates was 4μg/ml for all isolates, except E.coli was 8μg/ml. Also, the silver particles showed an antifungal behavior against 4 fungal species (A. niger, P. marneffie, C. glabrata and C. parapsilosis) with an inhibition zone from 19 to 39mm in diameter. Whereas, the MICs for fungal isolates 8μg/ml for all isolates. Treated Wi-38 cells with AgNPs demonstrated various levels of cytotoxicity dependent on the concentration of AgNPs using MTT assay with IC50  447.6. Moreover, the current study presents a facile and cost-effective synthesis of AgNPs via green chemical methods to be used as antimicrobial agents. Further in-vivo assessment is required to evaluate their therapeutic efficacy against MDR microorganisms.