Interaction Between Hydrophobic Au Nanoparticles and Pulmonary Surfactant (DPPC) Monolayers.

Hydrophobic nanoparticles from the air get into the lungs through inhalation and firstly interact with pulmonary surfactant, which is essential for normal lung function. 1,2-dipalmitoyl-sn-glycerol-3-phosphocholine (DPPC) is the major component of pulmonary surfactant. Interaction between Langmuir monolayer of DPPC and hydrophobic Au nanoparticles (Au NPs) were investigated in this study by atomic force microscope. The experimental results indicated that incorporation of hydrophobic Au NPs into the monolayer hindered the phase transition, reduced the compressibility of monolayer and disrupted the large micro-domains in liquid-condensed (LC) phase into smaller ones. Moreover, Au NPs that modulated by DPPC domains formed wandering wires, which were enclosed LC phase domains, at low concentration and relatively large islands at high concentration. The large islands still remained on the water surface after five cycles of compression-expansion at high concentration of Au NPs, but single NPs or wires with 1-2 particle width escaped into the water during the compression through the help of DPPC coating. The interaction between hydrophobic NPs and pulmonary surfactant provides an insight into the toxicological effects of inhaled NPs from the atmosphere to the function of pulmonary surfactant in the lung.