Nose-to-brain transport of aerosolised quantum dots following acute exposure

Abstract

Nanoparticles are of wide interest due to their potential use for diverse commercial applications. Quantum dots (QDs) are semiconductor nanocrystals possessing unique optical and electrical properties. Although QDs are commonly made of cadmium, a metal known to have neurological effects, potential transport of QDs directly to the brain has not been assessed. This study evaluated whether QDs (CdSe/ZnS nanocrystals) could be transported from the olfactory tract to the brain via inhalation. Adult C57BL/6 mice were exposed to an aerosol of QDs for 1 h via nasal inhalation, and nanoparticles were detected 3 h post-exposure within the olfactory tract and olfactory bulb by a wide range of techniques, including visualisation via fluorescent and transmission electron microscopy. We conclude that, following short-term inhalation of solid QD nanoparticles, there is rapid olfactory uptake and axonal transport to the brain/olfactory bulb with observed activation of microglial cells, indicating a pro-inflammatory response. To our knowledge, this is the first study to clearly demonstrate that QDs can be rapidly transported from the nose to the brain by olfactory uptake via axonal transport following inhalation.

Keywords::

• qdots
• olfactory epithelium
• olfactory bulb
• inhalation

Acknowledgements

The authors thank the technical assistance of Dale Uyeminami, Janice Peake and Imelda Espiritu in the aerosolisation, fixation and preparation of nasal and olfactory bulb tissue sections for this study. The authors would also like to acknowledge the assistance of the researchers Thomas R. Huser and Stephen Lane at the Center for Biophotonics, an NSF Science and Technology Center managed by the University of Calfornia, Davis, under Cooperative Agreement No. PHY 0120999. This work was supported in part by EPA grant RD-83171401, NIEHS grant U01 ES 02027 and NIOSH grant 0H07550 to study the fate and transport of inhaled nanoparticles in the respiratory tract. LEH was supported in part through the Atmospheric Aerosols and Health (AAH) training grant under the UC Statewide Toxic Substances Research and Teaching Program.