Effect propagation after silver nanoparticle exposure in zebrafish (Danio rerio) embryos: a correlation to internal concentration and distribution patterns

Abstract

The zebrafish (Danio rerio) embryo (ZFE) is an established ecotoxicological test organism used to investigate the hazardous potential of chemicals. It has been frequently used to test nanoparticles (NPs) for adverse effects. Beyond the assessment of the effects, information on real exposure concentrations, particle uptake and distribution patterns as well as the determination of internal effect concentrations contributes to a deeper understanding of NP–organism interactions. The AgNP and AgNO₃ dose–response curves recorded for different ZFE developmental stages were corrected to real exposure concentrations measured by ICP-MS within this study. Effective concentrations of silver exerting toxic effects were determined by this approach. Organisms showing no effects and individuals with sublethal or lethal effects were compared with regard to silver distribution patterns and internal uptake concentrations in order to allow a more exact correlation. As a result, the internal silver dose per organism differs around 0.5–1 ng Ag per organism irrespective of the developmental stage. However, for earlier developmental stages (2 hours post fertilisation) the ZFE chorion was found to effectively adsorb silver, leading to an up to 20-fold increase in total silver concentrations compared to the later chorion-free stages of the ZFE. Finally, a correlation between increased internal silver (particulate and ionic) concentrations and the occurrence of sublethal and lethal effects was observed.