Age-Dependent Rat Lung Deposition Patterns of Inhaled 20 Nanometer Gold Nanoparticles and their Quantitative Biokinetics in Adult Rats

The increasing use of gold nanoparticles leads to a possible increase of exposure by inhalation. Therefore, we have studied the deposition patterns of inhaled 20 nm gold nanoparticles (AuNP) in 7−90 day old rats and their biokinetics in 60 day old ones. Wistar−Kyoto rats inhaled intratracheally 20 nm 195Au-radiolabeled AuNP by negative pressure ventilation over 2 h. Immediately afterward lungs were excised, inflated and microwave dried. AuNP deposition was analyzed by single-photon emission computed tomography, computed-tomography and autoradiography. Completely balanced, quantitative biodistributions in major organs and all body tissues and total excretion were analyzed from 1 h to 28 d after inhalation. Intratracheal inhalation caused AuNP deposition predominately in the caudal lungs, independent of age. About 30% AuNP were deposited on airway epithelia and rapidly cleared by mucociliary clearance. About 80% of AuNP deposited in alveoli was relocated from the epithelium into the interstitium within 24 h...