Biophysicochemical characterization of interaction between pulmonary surfactants and nanoparticles

Abstract

With the rapid development of nanotechnology and nanoscience, there is an increasing concern of the environmental, health, and safety (EHS) impacts of nano particles, which have a feature of particle size less than 100 nm in at least one dimension. Inhaled nanoparticles (NPs) must first interact with the pulmonary surfactant (PS) lining layer that covers the entire internal surface of the respiratory tract and plays an important role in surface tension reduction and host defense. Interactions with the PS film determine the subsequent clearance, retention, and translocation of the inhaled NPs, and hence their potential toxicity. To date, little is known how NPs interact with PS, and whether or not NPs have adverse effects on the biophysical function of PS. We found a time-dependent toxicological effect of hydroxyapatite NPs (HA-NPs) on natural PS, Infasurf, and the time scale of surfactant inhibition after particle exposure was comparable to the turnover period of surfactant metabolism. Using a variety of in vitro biophysicochemical characterization techniques, we have determined the inhibition mechanism to be due to protein adsorption onto the HA-NPs. Consequently, depletion of proteins from surfactant vesicles caused conversion of original large phospholipid vesicles into much smaller vesicles, which have poor surface activity. These small vesicles in turn inhibited biophysical function of surfactant films after adsorption at the air-water interface.