Interaction of functionalized fullerenes and metal accumulation in Daphnia magna

In aquatic environments, transformation of pollutants by association with functionalized carbon-based nanoparticles can dramatically change their cycling pathways. The present study quantified the uptake and depuration behavior of cadmium and zinc bound with functionalized fullerene nanoparticles (f-nC(60)) in a freshwater cladoceran, Daphnia magna, in a well-dispersed medium. Metal uptake proceeded with a linear pattern during the 8-h exposure period, and the uptake rate constants (ku) were 1.3-fold to 1.4-fold higher for Cd or comparable for Zn bound with f-nC(60) than those of the free ones. The assimilation efficiencies of Cd and Zn bound with f-nC(60) were significantly enhanced when compared with those metals bound with algal food. Furthermore, the depuration of metals bound with f-nC(60) was relatively slower compared to the depuration of metals bound with carbon nanotubes. A longer exposure to f-nC(60) resulted in an even slower depuration of metals. The authors conclude that metal binding with f-nC(60) as modified nanoparticles could serve as a new pathway for the elevated metal accumulation in Daphnia.