Influence of volatile organic compounds (VOCs) on pulmonary surfactant monolayers at air-water interface: Implication for the pulmonary health

Abstract

Abstract Understanding the interaction of pulmonary surfactant (PS) and volatile organic compounds (VOCs) at air-water interface is crucial for the assessment of pulmonary health. In this study, dipalmitoyl phosphatidylcholine (DPPC), the mainly effective components of PS, was used as a mimic of PS employed to explore its surface activity in the exposure of VOCs. The results showed that the surface tension of DPPC decreased significantly with the addition of VOCs. On a basis of structure-activity assessment, hydrogen-bond basicity and dispersion/cavity interaction of VOCs are responsible for the decreasing capacity of VOCs for DPPC’s surface tension. Surface pressure-molecular area (π-A) isotherms demonstrate that the phase conversion of DPPC monolayer from gas to liquid expanded phase was greatly impacted by VOCs. The collapse pressure of DPPC monolayer in VOCs exposure are lower compared to that of DPPC alone, which can be attributed to the lowest surface tension of DPPC solutions mixed with VOCs. Atomic force microscopy analysis elucidates that the presence of VOCs led to bigger apertures area of DPPC monolayer than that of DPPC alone, which is indicative of microstructure changes of DPPC monolayer in the exposure of VOCs. This study provides new evidences that the exposure of VOCs on DPPC may alter the air-water interface activity of PS.