Uptake of BDE-209 on zebrafish embryos as affected by SiO2 nanoparticles

It was hypothesized that interactions between emerging contaminants such as decabromodiphenyl ether (BDE-209) and nanoparticles (NPs) such as nano-SiO2 (nSiO(2)), can affect contaminant transport in the aquatic environment and its ecotoxicity. This study assessed the influence of nSiO(2) on the uptake of BDE-209 by zebrafish embryo. The distribution of BDE-209 and nSiO(2) on the external chorion and the internal embryo mass (i.e., dechorionated embryo) was measured. For single exposure of nSiO(2) to zebrafish embryo, separately, results showed that nSiO(2) accumulation on the chorion surface was higher than that in the dechorionated embryo. The nSiO(2) accumulation on the chorion surface was 129-200 mg-nSiO(2)/gchorion at 48 h post fertilization, hpf, of exposure time, whereas the equilibrium adsorption of nSiO(2) on the dechorionated embryo was ca. 0.42-0.54 mg-nSiO(2)/g-embryo at 6 hpf. Results showed that the formation of nSiO(2)-BDE-209 associates promoted both extracellular and intracellular uptake of BDE-209 by zebrafish embryo, thereby increasing the bioconcentration of BDE-209 on the chorion surface and in embryo. The results also revealed that the accumulation of BDE-209 on the chorion was remarkably greater than that on the dechorionated embryo at 48 hpf. The uptake of BDE-209 was 17.2 +/- 0.45 mg/g-chorion (or 86 ng-BDE-209/chorionated embryo) and 0.37 +/- 0.01 mg/g-embryo (or 18.6 ng-BDE-209/dechorionated embryo), respectively, when co-exposure of zebrafish embryos to BDE-209 and nSiO(2). Results from the SEM and EDS analysis revealed that nSiO(2) already passed through the chorion and adhered to the embryo surface/mass. (C) 2018 Elsevier Ltd. All rights reserved.