Transition Metal Nanoparticles: Gastrointestinal Modification after Oral Exposure

Faculty Researcher: Andrew Ault, PhD, Assistant Professor of Environmental Health Sciences and Chemistry at the University of Michigan

Professor Andrew Ault

Dr. Andrew Ault

Nanotechnology and its applications in many commercial and industrial processes has increased rapidly, however our understanding of nanoparticle health impacts is still developing. For example, the risks of worker exposure to nanoparticles and the effects they will cause are still highly uncertain. It is challenging to examine nanoparticles as their nanometer scale size causes them to have different characteristics than their bulk material. A through characterization of the particle prior to use is important is assessing particle changes upon introduction to the human body. Ingestion, whether intentional or not, is an important route of nanoparticle exposure. Despite the fact they have been understudied, nickel has received attention recently after a worker was exposed and experience numerous negative health effects, while cobalt oxide nanoparticles have received attention for their reactive oxygen species generation capacity and ability to easily enter cells. In this work, the dissolution/aggregation and modification of two transition metal-containing
nanoparticles, nickel (NiNP) and cobalt oxide (CoNP) was examined.

Nickel and cobalt particles

TEM Images of nickel and cobalt nanoparticles and their
projected area size distributions for A) NiNP and B) CoNP.

Results from this study show that in simulated stomach fluid (pH 2), NiNP and CoNP showed no change in size or concentration over a 15 minute time period. While this confirmed our hypothesis that these transition metal nanoparticles would not agglomerate as rapidly as particles such as AgNP, this was a negative result in terms of our hypothesis that these particles would have increased dissolution under these highly acidic conditions. Therefore, under these conditions, we would expect that little if any Co2+ or Ni2+ may be released from the particles, given there was no change in diameter and concentration for both nanoparticles. Though, this indicates that these particles will remain their given size as they pass through the stomach into the intestine, where uptake into or through the cells lining the lower gastrointestinal tract can occur. The NiNP and CoNP have the potential to exit the gastric system into the intestine at sizes between 100 and 200 nm, a size suitable for uptake via endocytic pathways, having the potential to cause negative health effects.

Project Abstract