Media ionic strength impacts embryonic responses to engineered nanoparticle exposure

Abstract

Embryonic zebrafish were used to assess the impact of solution ion concentrations on agglomeration and resulting in vivo biological responses of gold nanoparticles (AuNPs). The minimum ion concentration necessary to support embryonic development was determined. Surprisingly, zebrafish exhibit no adverse outcomes when raised in nearly ion-free media. During a rapid throughput screening of AuNPs, 1.2-nm 3-mercaptopropionic acid-functionalized AuNPs (1.2-nm 3-MPA-AuNPs) rapidly agglomerate in exposure solutions. When embryos were exposed to 1.2-nm 3-MPA-AuNPs dispersed in low ionic media, both morbidity and mortality were induced, but when suspended in high ionic media, there was little to no biological response. We demonstrated that the media ionic strength greatly affects agglomeration rates and biological responses. Most importantly, the insensitivity of the zebrafish embryo to external ions indicates that it is possible, and necessary, to adjust the exposure media conditions to optimize NP dispersion prior to assessment.

Keywords::

• Danio rerio
• ion concentration
• nanomaterial–biological interactions
• toxicity

Acknowledgements

The authors thank Sinnhuber Aquatic Research Laboratory for the embryos, Jane La Du for her assistance in preparation of this manuscript and John Miller for helpful discussions regarding nanoparticle preparation. These studies were partially supported by National Institute of Environmental Health Sciences (NIEHS), R01ES016896, P3000210, the Air Force Research Laboratory (AFRL) under agreement number FA8650-05-1-5041 and Environmental Protection Agency (EPA) RD-833320. The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of NIEHS, AFRL, EPA or the U.S. Government.