Interaction with the pulmonary surfactant film, being the first line of host defense, represents the initial bio-nano interaction in the lungs. Such interaction determines the fate of the inhaled nanoparticles and their potential therapeutic or toxicological effect. Despite considerable progress in optimizing physicochemical properties of nanoparticles for improved delivery and targeting, the mechanisms by which inhaled nanoparticles interact with the pulmonary surfactant film are still largely unknown. Here, using combined in vitro and in silico methods, we show how hydrophobicity and surface charge of nanoparticles differentially regulate the translocation and interaction with the pulmonary surfactant film. While hydrophilic nanoparticles generally translocate quickly across the pulmonary surfactant film, a significant portion of hydrophobic nanoparticles are trapped by the surfactant film and encapsulated in lipid protrusions upon film compression. Our results support a novel model of pulmonary surfactant lipoprotein corona associated with inhaled nanoparticles of different physicochemical properties. Our data suggest that the study of pulmonary nanotoxicology and nanoparticle-based pulmonary drug delivery should consider this lipoprotein corona.

Graphene oxide (GO) is the most common derivative of graphene and has been used in a large range of biomedical applications. Despite considerable progress in understanding its cytotoxicity, its potential inhalation toxicity is still largely unknown. As the pulmonary surfactant (PS) film is the first line of host defense, interaction with the PS film determines the fate of the inhaled nanomaterials and their potential toxicity. Using a coarse-grained molecular dynamics model, we reported, for the first time, a novel mechanism of toxicity caused by the inhaled GO nanosheets. Upon deposition, the GO nanosheets induce pores in the PS film and thus have adverse effects on the ultrastructure and biophysical properties of the PS film. Notably, the pores induced by GO nanosheets result in increasing the compressibility of the PS film, which is an important indication of surfactant inhibition. In vitro experiments have also been conducted to study the interactions between GO and animal-derived natural PS films, qualitatively confirming the simulation results.

The Eu-doped TiO2nanocrystals with different content of Eu3+and the Eu-doped TiO2-ZnO composite powders with different content of ZnO were prepared by sol-gel method. The X-ray diffraction (XRD) spectra and photoluminescence(PL) spectra indicated that all of the Eu-doped TiO2have anatase structure. It indicated that the incorporation of Eu3+can inhibit the transformation of TiO2from anatase to rutile phase. With the increase of the content of Eu3+, the luminous intensity first increased and then decreased, and luminescent properties were best when the content of Eu3+is 1.1%. Considering the Eu-doped TiO2-ZnO composite powders, with the increasing of the proportion of ZnO, a Zn2TiO4phase has been gradually generated. When the content of ZnO up to 40%, the luminescent properties are the best.