Uptake and depuration of gold nanoparticles in Daphnia magna

Abstract

This study presents a series of short-term studies (total duration 48 h) of uptake and depuration of engineered nanoparticles (ENP) in neonate Daphnia magna. Gold nanoparticles (Au NP) were used to study the influence of size, stabilizing agent and feeding on uptake and depuration kinetics and animal body burdens. 10 and 30 nm Au NP with different stabilizing agents [citrate (CIT) and mercaptoundecanoic acid (MUDA)] were tested in concentrations around 0.5 mg Au/L. Fast initial uptake was observed for all studied Au NP, with CIT stabilized Au NP showing similar rates independent of size and MUDA showing increased uptake for the smaller Au NP (MUDA 10 nm > CIT 10 nm, 30 nm > MUDA 30 nm). However, upon transfer to clean media no clear trend on depuration rates was found in terms of stabilizing agent or size. Independent of stabilizing agent, 10 nm Au NP resulted in higher residual whole-animal body burdens after 24 h depuration than 30 nm Au NP with residual body burdens about one order of magnitude higher of animals exposed to 10 nm Au NP. The presence of food (P. subcapitata) did not significantly affect the body burden after 24 h of exposure, but depuration was increased. While food addition is not necessary to ensure D. magna survival in the presented short-term test design, the influence of food on uptake and depuration kinetics is essential to consider in long term studies of ENP where food addition is necessary. This study demonstrates the feasibility of a short-term test design to assess the uptake and depuration of ENP in D. magna. The findings underlines that the assumptions behind the traditional way of quantifying bioconcentration are not fulfilled when ENPs are studied.Electronic supplementary materialThe online version of this article (doi:10.1007/s10646-014-1259-x) contains supplementary material, which is available to authorized users.

Bioaccumulation and in-vivo dissolution of CdSe/ZnS with three different surface coatings by Daphnia magna

“…The depuration rate constants (k e ; Table 2) of QEI (0.0057/h) and of QSH (0.0079/h) were lower than QSA (0.0189/h). Similar uptake and elimination patterns were observed when exposed to Au NP (Skjolding et al, 2014). Slow depuration kinetics were calculated (0.02-0.26/h) and were highly dependent on not only surface properties but also particle sizes.…”

Modeling the influence of physicochemical properties on gold nanoparticle uptake and elimination by Daphnia magna

“…At 24 h, the bulk of the nanoparticle body burden was present in the tail region, indicating rapid removal irrespective of food availability. Both Skjolding et al and Khan et al identified fast removal of gold citrate nanoparticles in the first few hours followed by a slower elimination in the presence of a food source. Interestingly, in these studies elimination from the slow compartment proceeded at least an order of magnitude more slowly than we observed, highlighting the sensitivity of elimination to differences in food source, water quality, and organism origin.…”

“…Alternatively, concentration at steady state can be predicted with kinetic constants that are species specific and are adaptable to variable exposure conditions [20]. Several studies used the kinetic approach to predict nanoparticle accumulation [4,5,8,[21][22][23][24], but few have sought to describe the effect of nanoparticle characteristics on biodynamic rate constants for uptake and elimination [21,24].…”

The uptake and elimination of ZnO and CuO nanoparticles in Daphnia magna under chronic exposure scenarios

“…Since CuO nanoparticles are only taken in by ingestion (as indicated below; copper salt may be taken in by additional mechanisms), a trade-off may occur between ingestion of algae and ingestion of nanoparticles. Similarly, Skjolding et al (2014) indicates that when fed on algae, the uptake of gold nanoparticles by D. magna is less efficient than when not fed. The high copper concentrations in the nanoparticle exposure and the electron microscopic study indicate that the nanoparticle aggregates are ingested by the daphnids and can be localized in the gut lumen but do not appear to penetrate the cells.…”