In vivo biodegradation of colloidal quantum dots by a freshwater invertebrate, Daphnia magna

Impacts of planktonic invertebrate, Daphnia magna, on the speciation of colloidal quantum dots (QD) were investigated using fluorescence spectromicroscopic technique. Well-dispersed GA/TOPOQD were prepared by forming a supramolecular assembly of hydrophobic TOPOQD with biomacromolecules (i.e., Gum Arabic, GA). Biological degradation of this nanomaterial was monitored by fluorescence spectromicroscopic methods. Our study confirmed the major uptake pathway of manufactured nanomaterials and in vivo biodegradation processes in a well-known toxicity test organism, D. magna. In addition, we also found that D. magna can induce significant deterioration of aquatic media by releasing fragments of partially degraded QD colloids. These biological processes may significantly change the predicted toxicities of nanomaterials in aquatic environments. Thus, we propose that the impacts of aquatic living organisms on the environmental fate of manufactured nanomaterials (MNs) should be carefully taken into account when assessing the risk of MNs to the environment and human health.

► Impacts of D. magna on the fate of colloidal QD were studied using fluorescence spectromicroscopy.
► Major uptake pathway and biodegradation processes of NPs in D. magna were confirmed in this study.
► D. magna can accelerate deterioration of aquatic environment by releasing partially degraded QD.
► These processes may significantly change the predicted toxicities of NP in aquatic environments.