Low temperature synthesis of various transition metal oxides and their antibacterial activity against multidrug resistance bacterial pathogens

We report on the synthesis and characterization of various transition metal oxides, ZnO, CuO, TiO2 and Fe2O3, using one pot wet chemical method at low temperature. The prepared metal oxide nanoparticles were characterized by X-ray diffraction (XRD), Raman and transmission electron microscopy (TEM) analyses. We tested antibacterial activity of as-prepared transition metal oxides against various multi-drug resistance bacterial pathogens such as Escherichia coli, Bacillus subtilis, Pseudomonas aeruginosa, and Staphylococcus aureus. XRD and TEM analyses revealed the average crystallite sizes were 18 nm, 20 nm, 10 nm and 22 nm for ZnO, CuO, TiO2 and Fe2O3 nanoparticles, respectively. Further, the bacterial strains were grown in presence of different concentrations of four nanoparticles and it is evident from the results that ZnO, CuO nano particles showed greater bactericidal effect than nano-TiO2 and nano-Fe2O3, though nano-TiO2 possess less particle size than other fabricated metal oxide nanoparticles

Green synthesis of silver nanoparticles using methanolic root extracts of Diospyros paniculata and their antimicrobial activities

Since the discovery and subsequent widespread use of antibiotics, a variety of bacterial species of human and animal origin have developed numerous mechanisms that render bacteria resistant to some, and in certain cases to nearly all antibiotics, thereby limiting the treatment options and compromising effective therapy. In the present study, the green synthesis of nanoparticles is carried out by the reduction of silver acetate in the presence of crude methanolic root extracts of Diospyros paniculata, a member of family Ebenaceae. The UV-Vis absorption spectrum of the biologically reduced reaction mixture showed the surface plasmon peak at 428 nm, a characteristic peak of silver nanoparticles. X-ray diffraction (XRD) analysis confirmed the face-centered cubic crystalline structure of metallic silver. The average diameter of Ag NPs is about 17 nm from Transmission Electron Microscopy (TEM) which is in good agreement with the average crystallite size (19 nm) calculated from XRD analysis. Further the study has been extended to the antimicrobial activity against test pathogenic Gram (+), Gram (-) bacterial and fungal strains. The biologically synthesized silver nanoparticles showed promising activity against all the tested pathogenic strains and the activity has been enhanced with the increased dose levels. (C) 2016 Elsevier B.V. All rights reserved