The system worked optimally at temperature between 21 and 25 °C, without external cooling or heating of the glass tube. All experiments were performed under a hood in an air-conditioned room (variations between 21 and 25 °C). Mass flow was varied between 1 ml/min and 10 ml/min with best deposition rates at 5 ml/min. Deposition rates of fluorescein at 1 ml/min and at 10 ml/min were 0.19–0.36% (3rd compartment – 1st compartment) and 0.38–0.42% (3rd compartment – 1st compartment) of the deposition at 5 ml/min, respectively. Inhibitor Library ic50 Aerosolization in a variety of

solvents (distilled water, PBS, 0.9% saline, DMEM, DMEM + 2% FBS) did not cause morphological damage to the exposed cells. As nebulization in distilled water produced the highest deposition rates, this solvent was used for the exposures of polystyrene particles. The Epacadostat order established system used in all experiments worked with PariLC SPRINT baby, glass tube as inlet, at room temperature, with a flow rate of 5 ml/min and distilled water was used as solvent. For FluoSpheres an optimal deposition rate was

seen at 200 μg/ml whereas, 50 and 500 μg/ml showed lower deposition rates. CNTs were assessed at 50 μg/ml. Cells were exposed for 1 h and a volume of 10 ml for FluoSpheres and 8 ml for CNTs was nebulized. The MicroSprayer® IA-1C aerosolizer (PennCentury Inc., Wyndmoor, PA) consists of a thin, flexible, stainless steel tube measuring 0.64 mm in diameter and 50.8 cm in length attached to the light, hand-operated, high-pressure syringe FMJ-250. A unique patented atomizer at the very tip of the tube generates the aerosol with a mass median diameter of 16–22 μm (http://www.penncentury.com/products/IA_1C.php).

The MicroSprayer was fixated at a distance of 11 cm between tip of the MicroSprayer and the rim of the 6-well plate. This distance was determined as optimal for a reproducible delivery of the aerosol. To deliver the aerosol in a reproducible way the syringe was actuated in one fast push. For safety reasons all exposures were performed in a HERAsafe® KS 9 clean bench (Thermo Scientific, Vienna) equipped with UPLA filters of both filter grades U15 and H14. Aerosols Casein kinase 1 with the MicroSprayer were generated with the same solvent as the VITROCELL/PARI BOY system (distilled water, PBS, 0.9% saline, DMEM, DMEM + 2% FBS) but in addition allowed aerosolization of substances in DMEM + 10% FBS. The maximum concentration of particles, which could be aerosolized without clogging of the aerosolizer tip and the maximum number of spray doses, which did not result in a continuous liquid layer on top of the cells, were determined. Polystyrene nanoparticles (1000 μg/ml suspended in DMEM + 10% FBS) and CNTs (500 μg/ml suspended in DMEM + 10% FBS) were applied in three spray doses (600 μl aerosol). For the exposures, transwells were transferred to another plate, the exposure plate, and subsequently replaced and cultured for additional 24 h.