ICON Web & News
Search Using OECD Database
Return to Previous Page
Addition or Correction
Chemical Transformations of Nanosilver in Biological Environments
Link to Journal Abstract
The widespread use of silver nanoparticles (Ag-NPs) in consumer and medical products provides strong motivation for a careful assessment of their environmental and human health risks. Recent studies have shown that Ag-NPs released to the natural environment undergo profound chemical transformations that can affect silver bioavailability, toxicity, and risk. Less is known about Ag-NP chemical transformations in biological systems, though the medical literature clearly reports that chronic silver ingestion produces argyrial deposits consisting of silver-, sulfur-, and selenium-containing particulate phases. Here we show that Ag-NPs undergo a rich set of biochemical transformations, including accelerated oxidative dissolution in gastric acid, thiol binding and exchange, photoreduction of thiol- or protein-bound silver to secondary zerovalent Ag-NPs, and rapid reactions between silver surfaces and reduced selenium species. Selenide is also observed to rapidly exchange with sulfide in preformed Ag2S solid phases. The combined results allow us to propose a conceptual model for Ag-NP transformation pathways in the human body. In this model, argyrial silver deposits are not translocated engineered Ag-NPs, but rather secondary particles formed by partial dissolution in the GI tract followed by ion uptake, systemic circulation as organo-Ag complexes, and immobilization as zerovalent Ag-NPs by photoreduction in light-affected skin regions. The secondary Ag-NPs then undergo detoxifying transformations into sulfides and further into selenides or Se/S mixed phases through exchange reactions. The formation of secondary particles in biological environments implies that Ag-NPs are not only a product of industrial nanotechnology but also have long been present in the human body following exposure to more traditional chemical forms of silver.
This paper summarizes the rich set of biochemical transformations that silver nanoparticles (Ag-NPs) undergo and proposes a conceptual model for Ag-NP transformation pathways in the human body.
Peer Reviewed Journal Article
Exposure Or Hazard Target
Method Of Study
Computational and System Modeling
Risk Exposure Group
ACS Nano, 2012, 6(11): 9887-9899
Liu J, Wang Z, Liu FD, Kane AB, Hurt RH
Last updated on December 10, 2012
This work is supported in part by the Nanoscale Science and Engineering Initiative of the National Science Foundation
under NSF Award Number EEC-0118007.
Why Join Us?
Mission and Strategy
Good Nano Guide
Nano EHS Research Needs
Current Practices Survey