Salinity-dependent silver nanoparticle uptake and transformation by Atlantic killifish (Fundulus heteroclitus) embryos

Abstract

We assessed the biodistribution and in situ speciation of sub-lethal concentrations of citrate-coated silver nanoparticles and dissolved silver within Fundulus heteroclitus embryos. Using a thorough physico-chemical characterization, we studied the role of salinity on both uptake and in situ speciation. The Ag uptake or adsorption on the chorion was reduced by 2.3-fold for Ag NPs, and 2.9-fold for AgNO3 in estuarine water (10‰ ASW) compared to deionized water (0‰ ASW). Between 58% and 85% of the silver was localized on/in the chorion and formed patches between 20 and 80 µm. More than a physical barrier, the chorion was found to be a chemically reactive membrane controlling the in situ speciation of silver. A strong complexation of the Cit-Ag NPs with the thiolated groups of proteins or enzymes of the chorion was responsible for the oxidation of 48 ± 5% of the Ag(0) into Ag((I))-S species at 0‰ ASW. However, at 10‰ ASW, the presence of Cl(-) ions at the surface of Ag NPs slow down this oxidation. For the dissolved silver, we observed that in deionized water 69 ± 7% of Ag(+) taken up by the chorion was complexed by the thiolated molecules while the others 30 ± 3% were reduced into Ag(0) likely via interaction with the hemiacetal-reducing ends of polysaccharides of the chorion.

Metal uptake and distribution in the zebrafish (Danio rerio) embryo: differences between nanoparticles and metal ions

“…1a, Ag-NPs strongly associate with the chorion and substantial amounts seem to reach the PVS, whereas only minor amounts reach the embryo. A high sorption of Ag-NPs to the chorion structure was previously reported and quantified by Auffan et al (2014) 28 with a percentage of 58 to 85% Ag-NPs accumulating at the chorion after 48 h of exposure to 5 mg l −1 Ag-NPs. Ionic silver stemming from the AgNO 3 solution was predominantly located in the PVS and to a lesser extent in the chorion (Fig.…”

“…26,27 A barrier function of the chorion was likewise reported for several other NPs, namely Ru@SiO 2 particles (60, 200 nm), 17 as well as CuO-, ZnO-, Co 3 O 4 -, and NiO-NPs (all NPs with a primary particle size of 20-50 nm). 18 Furthermore, Auffan et al (2014) 28 concluded that the chorion acts as a protective membrane limiting the internalization of NPs as well as metal cations.…”

Influences of temperature and salinity on physicochemical properties and toxicity of zinc oxide nanoparticles to the marine diatom Thalassiosira pseudonana

“…The 96-h LC50s of ZnO-NPs for the marine copepod Tigriopus japonicus were 1.22 mg/L and 2.44 mg/L at salinities of 5 and 35 ppt, respectively 8 . After exposure to citrate-coated silver nanoparticles (5 mg/L) for 48 h, uptake of silver by embryos of the Atlantic killifish Fundulus heteroclitus was more than 2-fold greater in freshwater (0 PSU) than in brackish water (10 PSU) 36 . Consistent with the results presented here, results of another study showed that the 96-h IC50s of ZnO-NPs to T .…”

The influence of salinity on the fate and behavior of silver standardized nanomaterial and toxicity effects in the estuarine bivalve Scrobicularia plana

“…In the present study, we decided to look further into the mechanisms of toxicity occurring at higher salinity (15 psu and 30 psu). Based on Auffan et al [10], we hypothesized that at such a salinity (15-30 psu), Ag bioaccumulation would be different compared with freshwater because of varying dissolution rates as a function of salinity [11]. Experimental evidence also shows that dissolved Ag is less bioavailable at higher salinities than at lower ones, mainly because of differences in dissolved Ag speciation between salinities [12].…”