PARI LC SPRINT nebulizers are commonly used for inhalation treatment by patients and the aerosol composition used in our study is therefore similar to that inhaled by patients. With both aerosol-generating systems the amount of nanoparticles, which could be applied to cells was limited and concentration, where cytotoxicity was expected based on conventional testing in suspensions, were only reached for amine-functionalized polystyrene particles. With these particles a significantly higher cytotoxicity was seen upon aerosol exposure than when applying nanoparticles in suspension. The VITROCELL/PARI

BOY system presented in this study allowed testing of nanoparticle based aerosols in a physiological exposure and without causing cell damage by the exposure system itself. see more The deposition rates of 0.175% for the reference substance and a maximum of 0.037% for aerosolized polystyrene particles in the VITROCELL/PARI BOY system are, however, lower than those of other existing systems. For instance, using the ALICE system (Lenz et al., 2009) for in vitro exposure 7.2% of the dose were delivered to an area of two 6-well plates (215.9 cm2). Cells cultured in an insert, therefore, would receive 0.157% of the total nebulized nanoparticle dose. Using a nose-only inhalation in mice only 0.008% of the nebulized dose reached the lung (Nadithe et al., selleck compound 2003). Even upon instillation into the lung at the bifurcation of the trachea

only 5% of the aerosol reaches the lung periphery where absorption can take place. In rabbits with tracheostoma, a model for the neonatal lung, deposition by nebulizers has been reported between 0.05% and 1.96% (Cameron et al., 1991 and Flavin et al., 1986). Regarding the deposition rate of polystyrene particles, the MicroSprayer is much

more efficient because the delivery rate is more than 700 times higher than the Bupivacaine VITROCELL/PARI BOY system. For the assessment of conventional substances and polystyrene particles the VITROCELL/PARI BOY system also has the disadvantage that the deposition rate is not the same for all compartments of the system. The observed decrease in the deposition rate from the 1st to the 3rd compartment appears to be inherent to the system but affects aerosolized conventional substances and nanoparticles to different degrees. Taking the low absolute deposition rates of the polystyrene particles in this system and the sensitivity of the fluorescence plate reader into account, the significance and the relevance of the observed differences could, however, be questioned. For the evaluation of CNTs the differences between VITROCELL/PARI BOY system and MicroSprayer were less pronounced; the distribution between the compartments of the VITROCELL/PARI BOY was more homogeneous and the Microsprayer delivered only about 4 times more CNTs to the wells. CNTs have a much higher tendency to form aggregates (Lee et al.