Direct Visualization and Quantification of Maternal Transfer of Silver Nanoparticles in Zooplankton

The immense application of silver nanoparticles (AgNPs) in biomedical fields is likely to increase the exposure of humans. However, little is known about whether these nanoparticles can be maternally transferred, especially regarding their biodistribution in the younger generation, maternal transfer efficiency, and toxic effects. In the present study, maternal transfer of AgNPs in model zooplankton (Daphnia magna) was for the first time visualized and quantified. We found that AgNPs were transferred from mother to offspring and mainly accumulated in the lipids due to the strong colocalization with lipid droplets, which were the major energy sources of Daphnia embryos. In contrast, Ag+ was irregularly distributed in different sites, probably due to the mobility and reactivity of Ag+. The maternal transfer efficiency quantified by the radiolabeling methodology was 2.37 +/- 0.25 and 6.05 +/- 0.89% for (110m)AgNPs and Ag-110m, respectively. Furthermore, AgNPs and Ag+ significantly inhibited the reproduction capability of F-0 and F-1 generations, but such maternal toxic effect inhibition was only found within the first two broods of F-0 and F-1 generations. Our bioimaging findings demonstrated that AgNPs could be maternally transferred to the next generation; thus, it is critical to produce AgNPs with lower toxic effects, higher delivery efficacy, and more precise targeting.