On the formation and extent of uptake of silver nanoparticles by live plants
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In this work we investigate the limits of uptake of metallic silver by two common metallophytes, Brassica juncea (BJ) and Medicago sativa (MS) and assess the form and distribution of the metal once sequestered by the plants. BJ accumulated up to 12.4 wt.% silver when exposed to an aqueous substrate containing 1,000 ppm AgNO3 for 72 h, however silver uptake was largely independent of exposure time and substrate silver concentration. MS accumulated up to 13.6 wt.% silver when exposed to an aqueous substrate containing 10,000 ppm AgNO3 for 24 h. In contrast to BJ there was a general trend for MS showing an increase in metal uptake with a corresponding increase in the substrate metal concentration and exposure time. In both cases the silver was stored as discrete nanoparticles, with a mean size of ∼50 nm. According to the hyperaccumulation definition of Brooks et al. (Brooks RR, Chambers MF, Nicks LJ, Robinson BH (1998) Phytomining. Trends Plant Sci 3:359–362), this is the first report of the hyperaccumulation of silver in any plant species.
KeywordsPhytoextraction Silver nanoparticle Synthesis Nanobiotechnology
The authors gratefully acknowledge the support of the University of Sydney Research and Development Fund. Roza Bali is grateful for the financial support of the Richard Claude Mankin Scholarship Fund at the University of Sydney. The authors acknowledge the assistance of Dr Pall Thordarson and Ms Emine Korkmaz at the Sydney University Electron Microscopy Unit and Dr Jeffrey Shi and Mr Adam Lumb for assistance with the AAS analysis. Correspondence and requests for materials should be addressed to Andrew Harris.
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