Three-layered silver nanoparticles to trace dissolution and association to a green alga. Issue 9 (21st October 2019)

• Record Type: Journal Article
• Authors: Ponton, Dominic E.; Croteau, Marie-Noële; Luoma, Samuel N.; Pourhoseini, Sahar; Merrifield, Ruth C.; Lead, Jamie R.
• Is Part Of: Nanotoxicology. Volume 13:Issue 9(2019)
• Page Start: 1149
• Page End: 1160
• Publication Date: 2019-10-21
• Subjects: Silver -- nanoparticles -- algae -- core-shell -- cell-association; Toxicology -- Periodicals; 615.9
• DOI: 10.1080/17435390.2019.1640912
• Languages: English
• ISSNs: 1743-5390

Abstract

Abstract: 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 AgNO3 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 ( kuw ) for total Ag (AgNP+D ), NPs (AgNP ) and AuNP were similar and 2.2-fold higher than the one from AgD 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 AgD . Third, the significantly lower AgNP /Au ratio measured with the algae after exposure (2.1 ± 0.1) compared to the AgNP /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.