The TEER values in our selleckchem cell cultures were close to what has been previously demonstrated by us and others under similar duration and conditions.(15,25,37) Preservation of tight junctions upon particle exposure has been also shown in our previous studies.(20) Imaging of the NPs using LSM in the airway epithelial cells did not reveal any particle within the junctions but only attached to the surface of the cells or in the cells. Ozone-induced nuclear translocation of NPs is a novel finding and has not been demonstrated before. Specific peptide mediated targeted delivery of gold NPs has been shown before.(38,39) Moreover, there are evidences that support nuclear accumulation as an methodological artifact.(40) Our studies, however, carefully incorporate normal and diseased air exposed controls that exclude such nonspecific deposition.

The mechanism of the nuclear uptake is not clear, given that size of nuclear pore is smaller than NPs used in this study. Ozone exposure may contribute to a transient nuclear pore modulation to cause uptake of the particle. A nonspecific transiently increased nuclear pore size, allowing entry of larger particles, upon inhibition of protein synthesis has been demonstrated before.(41) Therefore, particulate entry in nucleus may be a nonspecific uptake. The nuclear pore does disassemble and quickly reassemble, potentially capturing particulates in the process of cell division but cell cultures growing on inserts normally do not divide. Role of nucleolin, a protein of the nucleolus in trafficking of nanoparticles and its modification by steroids has recently been demonstrated.

(42) Nuclear entry of polylysine nanoparticles (73nm hydrodynamic diameter) was also observed in chochlear cells.(42,43) Further confirmatory methods may be required to study this phenomenon. Development of aerosolized drug delivery for various airway diseases including CF has improved considerably.(44,45) Novel, functionalized NPs and coatings have already shown promise.(46) Further, modified magnetofection techniques to enable penetration of physical barriers such as mucus show improved benefit for delivering therapeutic genes to treat CF.(47) However, studies on toxicity, to evaluate safety of such materials, are generally focused on particles greater than 1��m. Moreover, studies evaluating the impact of environmental factors on particle deposition and toxicity are absent.

Although our results demonstrate that the synthetic NPs used in this study do not modulate ozone-induced pro-inflammatory Dacomitinib response and cytotoxicity of non-CF and CF airway epithelial cells it is important to reevaluate the effect with each NP of interest. In conclusion, this study demonstrates detection and localization of NPs in normal and CF cells cultured at ALI by flow cytometry and by LSM.