Efficient synthesis of plant-mediated silver nanoparticles and their screening for antimicrobial activity

Now days, the development of safe, cost effective, reliable and eco-friendly processes for the synthesis of nanoparticles is an important aspect of nanotechnology. Among the various agents, plants show immense potential for the synthesis of nanoparticles. The bio-molecules found in plants induce reduction of Ag+ ions from silver nitrate to silver nanoparticles (AgNPs); therefore, in the present work, the aqueous leaves extract of the plant was used as reducing agent for the synthesis of silver nanoparticles. We synthesized extracellular silver nanoparticles using extract of the leaves of four different medicinal plants which act as a reducing agent at room temperature. The characteristic color change was observed on addition of plant extract to the silver nitrate solution due to their specific properties (Surface Plasmon Resonance). UV-Vis spectroscopy was used for the characterization of the silver nanoparticles. Green synthesized nanoparticles are evaluated for their antimicrobial activity against the Gram-positive and Gram-negative bacteria as well as two pathogenic fungi Aspergillus fumigatus and Curvularia lunata. The silver nanoparticles (SNPs) of selected plant parts have shown more toxicity towards bacterial species than that of the fungal species. Comparing with simple plant extracts, the SNPs exhibited greater antimicrobial efficacy and advantage over conventional antibiotics to which these microorganisms usually impart resistance