Mechanisms of Uptake and Translocation of Nanomaterials in the Lung.

Nanomaterials are invading our environment due to their increasing use in a very broad range of sectors making human exposure foreseeable during the life cycle of these materials. Inhalation is one of the most frequent routes of exposure in case of unintentional exposure and the small size of nanomaterials allows them to reach the deep lung. Understanding the fate and effects of nanomaterials is a great challenge for scientists as they exhibit a huge physico-chemical diversity that drives their biological reactivity. It is critical to determine the fate of nanomaterials at their route of entry in the organism as this will determine their local and/or systemic effects. In this review we will describe the epithelial barriers and the clearance processes of the respiratory tract. The mechanisms involved in the internalization of nanomaterials by respiratory cells and their ability to cross the epithelial barrier will be presented, highlighting methodologies and the role of the nanomaterial physico-chemical properties.