Fig. 4

Effects of deposited DEPs on A549 alveolar cells at 24 h post-exposure. a 3D—confocal laser scanning images of deposited DEPs at 20, 40, and 80 µg mL⁻¹ on the A549 monolayer, scale bar: 50 μm. Cell nuclei and F-actin cytoskeleton are stained with DAPI (cyan) and Phalloidin (magenta), respectively. b A549 monolayer integrity is assessed with transepithelial electrical resistance (TEER) measurement and 5 mM of ethylenediaminetetraacetic acid (EDTA) as a positive control. The viability of the A549 cells is evaluated with the release rate of cytosolic lactate dehydrogenase (LDH) in the apical and basal fractions. The means ± SD of three independent experiments performed in duplicates are displayed (N = 3). c Thermal emission of deposited DEPs at 20, 40, and 80 µg mL⁻¹ on the A549 monolayer determined with the LIT, scale bar: 1 cm. * represents (p < 0.05), ** (p < 0.01), *** (p < 0.001), **** (p < 0.0001)