The influence of cerium oxide nanoparticles on the surface activity of pulmonary surfactant

In recent years there has been an intensive development of industries that use or produce materials in the nano scale. Nanomaterials contribute to the improvement of the product parameters, but when inhaled can also negatively affect the human body. The aim of the study was to investigate the effect of cerium oxide nano particles on the surface activity of pulmonary surfactant (PS) forming a thin film separating the inhaled air from the alveolar epithelium. Three types of cerium oxide powders were used (Sigma-Aldrich): Cl having a particle size smaller than 25 nm, C2 having a particle size smaller than 50 nm, and for comparison purposes C3 having a particle size smaller than 5 mu m. Measurement of specific surface area was carried out using a Gemini 2360 surface area analyzer (Micromeritics, USA). The effect of cerium oxide nanoparticles on the surface activity of PS was studied using DeltaPi microtensiometer (Kibron Inc., Finland). Reconstituted animal surfactant preparation (Beractantum; Abbott Laboratories, France) recommended in states of deficiency of endogenous PS in newborn premature infants, was used as model PS. The tests were carried out at different particle concentrations (ranging up to 1 mg/ml) prepared with the constant concentration of the surfactant solution (1.25 mg phospholipids/ml). The study showed that in all the analyzed cases, the presence of cerium oxide particles caused an increase in surface pressure (lowering of the surface tension) at the liquid -air interface. It was found that the intensity of these changes depends on the particle size, specific surface area and the particle concentration. With the increase in concentrations of the particles in the model surfactant suspension, a greater difference in surface pressure/tension was observed with respect to the initial value. The largest increase in surface pressure (6.4 +/- 1.1 mN/m) was observed in the presence of cerium oxide nanoparticles Cl, which were characterized by the smallest dimensions (smaller than 25 nm) and the largest surface area (33.3 m(2)/g). The results show that cerium oxide nanoparticles may have an influence on the surface activity of pulmonary surfactant in vivo and adversely affect the functioning of the human respiratory system.