Silver nanoparticles (AgNPs) have been widely applied in our daily life because of their antibacterial properties, and may be eventually released into the environment, presenting hazards to aquatic organisms. However, the toxic mechanisms of AgNPs are largely known. In the present study, I proposed a novel aggregation induced emission (AIE) method by coupling a fluorogenic silver ions (Ag⁺) sensor with AIEgen coated AgNPs (AIE-AgNPs) for in-situ and noninvasive visualizing the fate of AgNPs in aquatic organisms. AgNPs accumulated in Daphnia were mainly distributed in gut, while the dissolved Ag⁺ was concentrated in both gills and gut. At the dissolution equilibrium state, 9.7% and 8.3% (wt. % of NPs) of 20 and 60 nm citrate coated AgNPs (Cit-AgNPs) dissolved, respectively, which...[ Read more ]

Silver nanoparticles (AgNPs) have been widely applied in our daily life because of their antibacterial properties, and may be eventually released into the environment, presenting hazards to aquatic organisms. However, the toxic mechanisms of AgNPs are largely known. In the present study, I proposed a novel aggregation induced emission (AIE) method by coupling a fluorogenic silver ions (Ag⁺) sensor with AIEgen coated AgNPs (AIE-AgNPs) for in-situ and noninvasive visualizing the fate of AgNPs in aquatic organisms. AgNPs accumulated in Daphnia were mainly distributed in gut, while the dissolved Ag⁺ was concentrated in both gills and gut. At the dissolution equilibrium state, 9.7% and 8.3% (wt. % of NPs) of 20 and 60 nm citrate coated AgNPs (Cit-AgNPs) dissolved, respectively, which was much more than that of AIE-AgNPs (1.71 %). While 81.06 % of AIE-AgNPs were excreted to external environment, 2.43±0.69 % of retentive AgNPs were transferred from mother to fetus, which were strongly colocalized with lipid droplets. In contrast, 6.34±3.33% of Ag⁺ transferred to fetus and distributed irregularly, probably attributed to its mobility and reactivity. In medaka larvae, intestine and liver were identified as major storage and potential action targets of AIE-AgNPs, which were dissolved and the released Ag⁺ was concentrated in the intestine, posing toxic effects to the intestine. At cellular level, AgNPs accumulated were concentrated in the lysosomes, while Ag⁺ was accumulated in the mitochondria. The intracellular dissolution of AIE-AgNPs was further quantified, and 18.8% of Cit-AgNPs and 11.1% of AIE-AgNPs dissolved, respectively. Such dissolution was higher than that in aqueous solution probably due to relative acidic microenvironment in lysosomes and the presence of large quantity of proteins, enzymes, ions, etc. These dissolved Ag⁺ released from AgNPs was then transported to mitochondria, potentially lead to the dysfunction of mitochondria.