The biodistribution and transformation of nanoparticulate and ionic silver in rat organs in vivo

Abstract

Determination of the biodistribution, transformation of nanoparticulate and ionic silver species is of significant importance for insight understanding mechanism behinds the toxicity of silver nanoparticles (AgNPs), which are widely used in numerous sectors. Their highly dynamic properties may lead to coexposure to nanoparticulate and ionic silver. Herein, an accurate speciation analysis of the biodistribution and transformation of the individual and co-administered particulate and ionic Ag in rat organs in vivo was performed by using a versatile analytical method developed for the separation, quantification and size characterization of different silver species in multiple rat organs (liver, spleen, heart, brain, lung and kidney), with mass detection limits of 0.1–0.2 μg/g for AgNPs and Ag(I), and size characterization precision of 0.2%–1.6% for AgNPs. Then, after intravenous (i.v.) exposure to either Ag+, AgNPs, or a mixture of Ag+ and AgNPs, the distribution of different silver species in rat organs was quantitatively determined. We found that most of the accumulated silver existed in complexed Ag(I) form in all organs, only a small fraction of AgNPs was detected in liver and lung, and the AgNPs taken up in organs were either rapidly and completely dissolved or maintained in their original core size in 3 days after exposure. More importantly, while there was a negligible combined effect on the uptake or redistribution of different silver species, the coexistence of Ag+ could accelerate the dissolution of administered AgNPs by the remarkable overexpression of metallothioneins.