AN X-RAY REFLECTIVITY INVESTIGATION OF A DEPOSITED LAYER OF THE NATURAL LUNG SURFACTANT

The morphology of natural lung surfactant and of two of its constituents, dioleylphosphatidylcholine (DOPC) and dipalmitoylphosphatidylcholine (DPPC), respectively representative of the unsaturated and saturated phospholipids of natural lung surfactant, has been investigated by X-ray reflectivity. Since the behavior of lung surfactant in in vivo dynamic conditions may be modeled by the compression-decompression of monolayers spread at the air-water interface, Langmuir-Blodgett sampling has been used to characterize its structures. The results reveal that the natural lung surfactant forms a monolayer covered with some crystallites, while DOPC forms a homogeneous monolayer, and DPPC piles up in multilayers. These results are related to the respreading mechanism of the studied monolayers. © 1991.