Quantum dots (QDs) change their size and surface properties in aquatic environments in the presence of extracellular polymeric substances (EPS) excreted from bacteria and phytoplankton, thus, agglomerate and/or even partly dissolve.  Cultures growing under nitrogen  (N) enriched or depleted conditions were exposed to amine- and carboxyl-functionalized QDs to determine the effects of N availability on the defense against Cd/Se QDs toxicity and the role of phytoplankton EPS in the fate of QDs. After 5-day incubation with QDs, no significant toxicity was observed to phytoplankton. Decreasing fluorescence of QDs over time indicated that the dissolution occurred during incubation, and the dissolution rate of QDs was higher in N-depleted cultures. Furthermore, amine-functionalized QDs showed lower dissolution rates and fluorescence decreasing, compared to carboxyl-functionalized QDs. The concentrations of polysaccharides and proteins were higher for the cultures exposed to QDs, suggesting that phytoplankton EPS can profoundly affect the mobility of QDs in aquatic environments.

Effects of extracellular polymeric substances of <i>Thalassiosira pseudonana</i> and nitrogen-depletion on the fate of Cd/Se quantum dots

243rd National Meeting (2012)

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Effects of extracellular polymeric substances of Thalassiosira pseudonana and nitrogen-depletion on the fate of Cd/Se quantum dots