Three-layered silver nanoparticles to trace dissolution and association to a green alga

Core-shell silver nanoparticles (NPs) consisting of an inner Ag core and successive layers of Au and Ag (Ag@Au@Ag) were used to measure the simultaneous association of Ag NPs and ionic Ag by the green alga Chlamydomonas (C.) reinhardtii. Dissolution of the inner Ag core was prevented by a gold (Au)...

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Bibliographic Details
Published in:Nanotoxicology 2019-10, Vol.13 (9), p.1149-1160
Main Authors: Ponton, Dominic E., Croteau, Marie-Noële, Luoma, Samuel N., Pourhoseini, Sahar, Merrifield, Ruth C., Lead, Jamie R.
Format: Article
Language:English
Subjects:
Algae
Aquatic environment
Aquatic plants
cell-association
Chlamydomonas reinhardtii - drug effects
core-shell
Dissolution
Exposure
Fluxes
Gold
Gold - chemistry
Metal Nanoparticles - chemistry
Metal Nanoparticles - toxicity
Nanoparticles
Rate constants
Silver
Silver - chemistry
Silver - toxicity
Solubility
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Summary:Core-shell silver nanoparticles (NPs) consisting of an inner Ag core and successive layers of Au and Ag (Ag@Au@Ag) were used to measure the simultaneous association of Ag NPs and ionic Ag by the green alga Chlamydomonas (C.) reinhardtii. Dissolution of the inner Ag core was prevented by a gold (Au) layer, while the outer Ag layer was free to dissolve. In short-term experiments, we exposed C. reinhardtii to a range of environmentally realistic Ag concentrations added as AgNO 3 or as NPs. Results provide three lines of evidence for the greater cell-association of NPs compared to dissolved Ag over the concentration range tested, assuming that cell-association comprises both uptake and adsorption. First, the cell-association rate constants (k uw ) for total Ag (Ag NP+D ), NPs (Ag NP ) and Au NP were similar and 2.2-fold higher than the one from Ag D exposure, suggesting predominant association of the particles over the dissolved form. Second, model calculations based on Ag fluxes suggested that only 6-33% of algal burden was from Ag D . Third, the significantly lower Ag NP /Au ratio measured with the algae after exposure (2.1 ± 0.1) compared to the Ag NP /Au ratio of the NPs in the media (2.47 ± 0.05) suggests cell-association of NPs depleted in Ag. Core-shell NPs provide an innovative tool to understand NP behavior and to directly delineate Ag accumulation from ion and NPs in aquatic systems.
ISSN:1743-5390
1743-5404
DOI:10.1080/17435390.2019.1640912