Uptake and Elimination Behaviors of Polyethyleneimine (PEI)-Coated Multi-Walled Carbon Nanotubes by Eisenia foetida and Daphnia magna

摘要

Determining the effects of various surface coatings on carbon nanotubes (CNTs) is critical given the numerous expected applications of CNTs and their inevitable release into ecosystems. To explore the potential ecotoxicological effects of CNT surface modifications, we modified multi-walled carbon nanotubes (MWNTs) with polyethyleneimine (PEI) coatings. Uptake and elimination experiments for PEI-MWNTs with various surface charges spiked to soils revealed limited earthworm accumulation and ready elimination. Conversely, Daphnia magna, a filter-feeding aquatic invertebrate, accumulated substantial concentrations of PEI MWNTs and was only able to excrete them with algae feeding. This suggests that the availability of food in ecosystems will substantially affect the long-term fate of nanotubes ingested by daphnia. Uptake was quantified in both species using carbon-14 labeled nanotubes.