Bioimaging of Trophic and Maternal Transfer of Silver Nanoparticles in Aquatic Organisms

Silver nanoparticles (AgNPs) have numerous applications for biological labeling, cancer treatment, biosensing, antibacterial activity, and antiviral activity. Their wide application increases the likelihood of AgNPs reaching the water systems, with the possibility of bioaccumulation in aquatic organisms, raising potential health and environmental concerns. A comprehensive understanding of the potential impacts of these nanoparticles on aquatic ecosystems is therefore required. In addition to direct bioaccumulation, these nanoparticles may be transferred up the food chains or maternally transferred to the next generation, but these aspects remain critically under-studied. Trophic and maternal transfers are important pathways for the movement of nanoparticles and have significant implications for the prediction of exposure and toxicity of nanomaterials in aquatic ecosystems. During complex trophic and maternal transfer, AgNPs and Ag+ can be redistributed and transformed biotically or abiotically, thus causing changes in the physical and chemical characteristics of the particles. Nevertheless, knowledge of the biodistribution patterns of AgNPs and Ag+ during trophic and maternal transfer is still very limited, mainly because of the lack of advanced technologies. In this project, I propose to employ novel fluorescent (aggregated-induced emission based) technology to address three exciting aspects of the toxicology of nanoparticles in aquatic environments, including transport and transformation, trophic transfer and maternal transfer, in two model aquatic organisms (Daphnia and Japanese medaka). We have successfully developed different Ag probes to visualize the distribution of both Ag+ and AgNPs directly in these organisms. Our primary objectives will be to 1) differentiate the distribution of Ag+ and AgNPs and their transport following bioaccumulation; 2) visualize the trophic transfer of Ag+ and AgNPs; 3) visualize the maternal transfer of Ag+ and AgNPs. We will perform various bioimaging analyses combined with the classic tracer labelling technique to visually and quantitatively evaluate the fate of both AgNPs and Ag+ during their trophic and maternal transfer. With the help of fluorescence techniques, it is now possible to observe the fate of AgNPs and Ag+ directly in the organisms. The application of novel bioimaging techniques allow us to address the most pressing questions such as whether these nanoparticles can be transferred further along aquatic food chains or maternally to the next generation of aquatic animals. We anticipate producing the first bioimaging data of NPs in aquatic animals following their trophic and maternal transfer, which are critical to any risk assessment of NPs in aquatic environments.