Biosynthesis of silver nanoparticles using flower extract of Cassia roxburghii DC and its synergistic antibacterial efficacy

In the present study, green synthesis of silver nanoparticles (AgNPs) was attempted using flower extract of Cassia roxburghii belonging to the family Fabaceae. Synergistic antibacterial activity of AgNPs with 15 commercial antibiotics was evaluated against 2 Gram-positive bacteria (S. aureus and B. cereus), 2 Gram-negative bacteria (E. coli and P. aeruginosa) and 4 fungi, which included one clinical isolate ( C. glabrata, C. albicans, C. neoformans and 1 Candida sp., clinical isolate). Characterization of synthesized AgNPs was done by various spectral analysis, including UV-Vis spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, Transmission electron microscopy and zeta potential. The UV-Vis spectrum of AgNPs showed absorption maxima at 348 urn. TEM analysis revealed that AgNPs were flower-like and/or triangular in shape, ranging from 5 to 360 nm in size. The antibacterial activity of AgNPs with antibiotics was better than antibiotics alone against the tested bacterial strains. The highest enhancing effects were observed for 7 antibiotics against S. aureus. This is a simple, economic, ecofriendly, nontoxic, quick and green synthesis of AgNPs using an aqueous flower extract of Cassia roxburghii. It can be definitely used in cosmetics, foods and medical applications. (C) 2014 Sharif University of Technology. All rights