nanotoxicity for e. coli and characterization of silver quantum dots produced by biosynthesis with eichhornia crassipes

nanomaterials (nms) 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 (ag nps)  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 nps  were biosynthesized with an  eichhornia crassipes (ec) 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 agnps; 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 agnps dissolutions were used for the nanotoxicity experiments. . the cytotoxicity  of agnps in a suspension was tested using the agnps synthesized with leaves, against escherichia coli atcc 25992 (e. coli) 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 nps 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 nps were mostly ago. the cytotoxicity  of ag nps in a suspension  tested using the ag nps on e. coli was highly effective towards inhibition of bacterial growth.