Green Synthesis of Silver Nanoparticles and Their Antibacterial Activity

Silver nanoparticles (Ag NPs) could be prepared by effective and simple biosynthesis by using plant extracts. Water extracts from Thymus serpyllum L., Thymus vulgaris L., and Sambucus nigra L. were used for a green synthesis of Ag NPs. Progress of the syntheses, the structure of Ag NPs and their antibacterial actiivity were followed by UV-Vis spectroscopy, TEM analysis and agar well diffusion method. UV-Vis analysis showed that the reactions performed with various plants extracts need different temperatures (60–90 °C) to synthesize Ag NPs. The NPs prepared were approx. 30 nm in size, but Ag NPs smaller than 10 nm were detected, too. Pure plant extracts without nanoparticles had no antibacterial activity. Of the Ag NPs-containing samples, only those prepared by using extract from Sambucus nigra L. showed antibacterial activity against Escherichia coli and Staphylococcus aureus. Green synthesis is a promising way to prepare NPs with biological activities.