جستجوی مقالات مرتبط با کلیدواژه « e. coli » در نشریات گروه « شیمی »

Nanomaterials are widely used in health and biomedical applications, however, only a few studies investigate their toxic effects. The present report signifies a contribution to the study of the toxic effects of silver nanoparticles on E. coli cells, which is a model organism of anthropogenic pollution. The toxicity of nanoparticles depends on their chemical and surface properties, shape and size. Nanoparticles that have the same chemical composition but different shapes or sizes might have different effects on cells. In this work, Ag nanoparticles were biosynthesized with an Eichhornia crassipes biomass, and it was demonstrated for the first time, that the amounts of hydrolysable tannins in this plant, are directly related to the size, shape, structure and composition of the Ag nanoparticles ; furthermore, the toxic effect was studied using E. coli cell culture. The EC was divided in three sections, i.e. roots, stems and leaves. Particle aggregation seems to be influenced by the amount of tannins present in the biomass. For each plant part, the amounts of hydrolysable tannins were determined, the highest amounts of these chemicals were present in the leaves, and hence these Ag nanoparticles dissolutions were used for the nanotoxicity experiments. . The cytotoxicity of Ag nanoparticles in a suspension was tested using the Ag nanoparticles synthesized with leaves, against Escherichia Coli ATCC 25992 where the concentration that inhibited 100% of bacterial growth, was 5 mg/L in contrast with a commercial solution which needed 10mg/L of Ag. For the most part, the Ag nanoparticles seemed to be of a nearly spherical shape, although on closer examination were determined to be mainly polyhedral. Leaves biomass, produced mainly quantum dot nanoparticles with sizes below 10 nm and the Ag nanoparticles were mostly AgO. The cytotoxicity of Ag NPs in a suspension tested using the Ag nanoparticles on E. coli was highly effective towards inhibition of bacterial growth.

Cadmium Oxide (CdO) nanoparticles were prepared by precipitation method using Cadmium acetate and ammonia solution. Presence of chemical species, were verified by Fourier Transform Infra Red (FTIR) Spectrum. From X-Ray Diffraction (XRD) spectrum the particle size, d-spacing value and structure of the nanoparticle were analysed. Size of the nanoparticles and the elemental composition were detected by using Scanning Electron Microscope (SEM) with Energy Dispersive X-Ray Analysis (EDAX). The optical band gap of CdO nanoparticles has been determined by using UltraViolet-Visible (UV-Vis) absorption spectroscopy. The antimicrobial activities of different concentration of the CdO nanoparticles were tested by treating E.coli cultures with CdO nanoparticles. Cadmium Oxide nanoparticles show effective antimicrobial activity. Different organisms were used to observe the zone of inhibition of CdO nanoparticles.