Metallic oxide nanoparticle translocation across human bronchial epithelial barrier – Supplementary information

16 nm-SiO2-FITC NPs production was performed in one step by adding a solution of 5 mL of fluorescent organosilane solution previously prepared mixed with 240 mL of ethanol 20 and 5 mL of TEOS into a 2 L round bottom flask containing 650 mL of EtOH, 2.4 mL of water and 24.1 mL of ammonia. The solution was let to react overnight at room temperature (RT) in the dark. 16 nm-SiO2-FITC NPs were purified against ultrapure water (18 MΩ) by tangential ultrafiltration with an 25 Amicon system (Millipore, Billerica, USA) equipped with a membrane of 100 kDa cut-off until disappearance of fluorescence in the filtrate. Batches of bigger sizes were purified by centrifugation. Before, ammonia and ethanol were removed from the medium by rotative evaporation at 40°C at 30 the end of the synthesis. The fluorescent particles were extensively washed by centrifugation against ultrapure water at 13,000 g for 15 min until disappearance of fluorescence in the supernatant. Estimation of silica concentrations in the dispersion was carried out by Inductively Coupled Plasma 35 (ICP) using an ICP Optical Emission Spectrometer (ICPOES) and a gravimetric method. For the production of 50and 100 nm-SiO2-FITC NPs, please refer to Vranic et al., 2013a1.