Effect of nanosized particles on pulmonary surfactant function
After inhalation, nanoparticles reach the deeper airways and get into contact with the pulmonary surfactant layer, whose main function is to lower surface tension in the alveoli. The aim of our study was to determine if nanosized particles induce a dysfunction of pulmonary surfactant. TiO2 (10 nm anatase and 1.3 µm rutile), plain (hydrophobic) and PEGylated (hydrophilic) polystyrene nanoparticles (50 nm) and quartz (2 µm) in increasing concentrations from 50 µg/ml up to 500 µg/ml were incubated with a natural porcine surfactant preparation (Curosurf). Phospholipid concentration was adjusted to 1.5 mg/ml in ringer solution. Surfactant function was measured in a pulsating bubble surfactometer. TiO2 nanoparticles and plain polystyrene nanoparticles at concentrations of 200 and 500 µg/ml caused slight but significant increases in adsorption surface tension. For TiO2 augmentations from 27.9 to 30.8 and 32.5 mN/m, respectively, and for plain polystyrene nanoparticles increases from 28.8 to 32.4 and 33.3 mN/m, respectively, were noted. Surface tension at minimal bubble size was increased at 500 µg/ml from 4.9 to 8.1 mN/m (TiO2) (p < 0.05) and from 3.8 to 6.4 mN/m (plain polystyrene particles) (p < 0.01). PEGylated polystyrene nanoparticles in each concentration induced significant decreases of adsorption surface tension (p < 0.001). Both tested microparticles did not affect surface tensions. Our results demonstrate that nanoparticles induce a slight surfactant dysfunction at high concentrations. We conclude that this effect is at least partly modulated by the hydrophobic/hydrophilic nature and the size of the particles. However, respective concentrations are manifold in excess of what is normally reached in vivo.