Biophysical Aspects Of Bio-Nanosilver Generated From Urtica Dioica Leaves And Vitis Vinifera Fruits' Extracts

Green chemistry principles were used to phytosynthesis of three types of silver nanoparticles (AgNPs) from aqueous extracts of: nettle (Urtica dioica) leaves, black grapes (Vitis vinifera fruits), and their mixture. The combination of these extracts proved to be the most potent bioreductant for Ag+, as compared to each extract alone. UV-Vis absorption and FT-IR spectroscopy proved the formation of silver nanoparticles. Total polyphenols' quantification of vegetal extracts and "green" AgNPs was carried out by Folin-Ciocalteu analysis. Structural (XRD) analysis revealed crystalline nature of bio-developed AgNPs. Morphological studies (AFM) showed spherical shape and the nano-scale dimensions of the obtained metallic nanoparticles. Physical stability of "green" developed nanoparticles was estimated by zeta potential measurements, and their biological activity was checked by evaluating the antimicrobial and the antioxidant potency. AgNPs phyto-generated from a combination of two extracts (nettle and grapes) proved to be the most bio-active, combining in a synergistic manner, the properties of nettle and grapes. These nanoparticles exhibited high antioxidant activity (AA = 89.4%) evaluated through chemiluminescence method, and strong antibacterial effect (showing an inhibition zone diameter of 20 mm) against Escherichia coli.