Biopersistence of Inhaled Nickel Oxide Nanoparticles in Rat Lung

Abstract

In order to investigate whether or not airborne nanoparticles with a minimum agglomeration could be used for exposure tests on animals, we developed a nanoparticle generation system and examined the biological effects of the particles in an inhalation study. The generation system was composed of an ultrasonic nebulizer and diffusion dryers, and 30 Wistar male rats were exposed to nickel oxide (NiO) nanoparticles for 4 wk (6 h/day). The geometric mean diameter of the particles and the daily average exposure concentration determined by a combination of a differential mobility analyzer and a condensation nucleus counter in the exposure chamber were 139 +/- 12 nm and 1.0 +/- 0.5 x 10(5) particles/cm3, respectively. At 4 days and 1 and 3 mo after the inhalation, each group of 10 rats were sacrificed and NiO nanoparticles deposited in the lung were determined by chemical analysis and the biopersistence (biological half time) was calculated. The deposited amount of NiO nanoparticles in the rat lungs at 4 days after the inhalation was 29 +/- 4 microg. The retained particle amount in the rat lungs after the inhalation exponentially decreased and the calculated biological half time was 62 days. The histopathological change was not severe just after the inhalation nor throughout the observation time. We concluded that nanoparticles with a minimum agglomeration were dispersed stably in the chamber and exposed to rats for 4 wk and that deposited amounts in the rat lungs and the biopersistence of the particles and the biological response in lung were detected.

Investigation of Gene Expression of MMP-2 and TIMP-2 mRNA in Rat Lung in Inhaled Nickel Oxide and Titanium Dioxide Nanoparticles

“…We previously instilled 200 μ g of NiO particles intratracheally to observe for 6 months and also did not find marked fibrosis 13,14) . The pulmonary deposition of the present study (deposited amount 4 d after the end of the inhalation) was 29 ± 44 μ g NiO 10) . Considering the dose-dependence of an intratracheal instillation study, no collagen deposition in the present study is likely to be reasonable.…”

“…Since the standard deviation of size and particle number of both nanoparticles in the chamber was not so large, the present study made it possible to carry out inhalation exposure to NiO and TiO 2 nanoparticles with a stable particle size and number concentration 10) . However, the agglomerated size of NiO nanoparticles was not nanoscale, but was more than 100 nm.…”

“…The generation and inhalation system of NiO nanoparticles was described in our previous paper 10) . The generation system was mainly composed of an ultrasonic nebulizer and diffusion dryers, connected to an exposure chamber (0.52 m 3 ).…”

NiO and Co3O4 nanoparticles induce lung DTH-like responses and alveolar lipoproteinosis

“…The kinetics of micron-sized nickel compounds showed that the half-life of an inhaled soluble form of a nickel compound (NiSO 4 ) was 2-3 days in rats and ,1 day in mice [24], while an insoluble form of a nickel compound (NiO; 2-2.4 mm) was 33 [24] or 120 days [25] in rats. The half-life of inhaled nanosized NiO (139¡12 nm) was 62 days in rats [26]. In this study, we have not challenged putative antigen at a distal site, since this was not the aim of the study; therefore, we have not demonstrated classical DTH.…”

Aerosol Generation by a Spray-Drying Technique Under Coulomb Explosion and Rapid Evaporation for the Preparation of Aerosol Particles for Inhalation Tests

“…The resulting aerosol particles, which were agglomerates of the primary particles, exhibited a geometric mean diameter (GMD) of 128 nm. Oyabu et al (2007) have generated nickel oxide (NiO) aerosol particles with a GMD of 139 nm from NiO nanoparticles with a primary size of 20 nm using an ultrasonic nebulizer.…”