Biologically Green Synthesis of High-quality Silver Nanoparticles Using Scrophularia striata Boiss Plant Extract and Verifying Their Antibacterial Activities

In the present work, we demonstrate a facile way to study the biosynthesis of silver nanoparticles (Ag-NPs) with strong bactericidal properties using an aqueous extract of Scrophularia striata Boiss. The bio-reduction of Ag+ ions resulted in FCC cubic structures of Ag-NPs with spherical shapes of about 16 nm. As a main aim of the present work, the antibacterial activity of the bio-synthesized Ag-NPs against Gram-negative (Escherichia coli and Salmonella typhi ATCC) and Gram-positive (Staphylococcus aureus and Bacillus cereus) bacteria was evaluated by disk diffusion method and results were compared with those of ciprofloxacin antibiotic. Interestingly the antibacterial activity of as-prepared Ag-NPs against all pathogenic bacteria was considerably higher than those obtained for Ciprofloxacin, and also better than the recent reports on the bactericidal activity of bio-synthesized Ag-NPs. As a simple, cost-effective and biocompatible method, the present work proposes a facile way toward bio-synthesis of large-scale Ag-NPs with an excellent antibacterial activity which can be suitable for future biological applications.