Biodistribution of gold nanoparticles in mouse lung following intratracheal instillation

The instilled nanoparticles were found in lung macrophages already 1 h after a single instillation. In mice instilled treated repeatedly during 3 weeks, the load was substantial. Ultrastructurally, AMG silver enhanced gold nanoparticles were found in lysosome-/endosome-like organelles of the macrophages and analysis with AMG, ICP-MS and NAA of the liver revealed an almost total lack of translocation of nanoparticles. In mice given repeated instillations of 2 nm gold nanoparticles, 1.4‰ (by ICP-MS) to 1.9‰ (by NAA) of the instilled gold was detected in the liver. With the 40 nm gold, no gold was detected in the liver (detection level 2 ng, 0.1‰) except for one mouse in which 3‰ of the instilled gold was found in the liver. No gold was detected in any liver of mice instilled with 100 nm gold (detection level 2 ng, 0.1‰) except in a single animal with 0.39‰ of the dose in the liver.We found that that: (1) inert gold nanoparticles, administered intratracheally are phagocytosed by lung macrophages; (2) only a tiny fraction of the gold particles is translocated into systemic circulation. (3) The translocation rate was greatest with the 2 nm gold particles.Epidemiological studies have reported associations between episodes of increased air pollution with particulate matter and adverse health effects in susceptible individuals [1-6]. It has been suggested, that the nanosized particles are the most dangerous fraction [7]. Air-borne nanoparticles (ultrafine particles) have been found to penetrate into the systemic circulation following inhalation [8,9]. Additionally, there is experimental evidence that respiratory exposure to nanoparticles may promote thrombosis [10,11]. It has been suggested that lung injury increases the degree of the nanoparticle translocation [12]. For a better understanding of the potential hazards of inhaled nanoparticles it is important to establish whether nanoparticles are translocated, i.e. transported through the alveolar barrier to the systemic ci