Do immature lungs have air-blood barriers that are more permeable to inhaled nanoparticles than those of fully-developed mature lungs? Data answering this question and explaining the underlying mechanisms do not exist. In this study, we exposed infant rats to gold nanoparticles and found that translocation of inhaled nanoparticles from air to the blood stream is surprising much higher in the infant lungs than that in the fully-developed adult lungs. The data also suggest that the mechanism of nanoparticle translocation in the infant lungs, which is size-independent, may be very different from that in adult lungs; paracellular transport mechanisms might be significantly involved. As far as we know, this is the first experimental demonstration of this phenomena; we believe therefore that our study is a significant step in the field of nanoparticle research and highly novel. It may potentially shed light on infant susceptibility to environmental particulates as well as open new research opportunities in terms of drug delivery applications using nanocarrier approaches.
We used gold nanoparticles, which although may be rare to encounter in real life, they have several advantages and are ideal as model particles for this study. First of all, gold is very dense (so that it is easy to be visualized), very insoluble, highly stable and toxicologically inert. Moreover, gold nanoparticles are well-studied and utilized widely in research. Therefore, there are lots of data, which can be used to compare with our data. Gold nanoparticles can be synthesized in a highly controllable manner in terms of their size, shape, and their surface chemistry. Our Center for Nanotechnology and nanotoxicology here at HSPH synthesizes engineered nanoparticles of different sizes, shapes and chemistry. (www.hsph.harvard.edu/nano).
For more details, the full article can be found in the September issue of ACS Nano.
