Transferred pulmonary surfactant film: chemical analysis and contact angle study

The Langmuir dip plate transfer technique was adapted to isolate the interfacial film formed at the surface of lung wash. The chemical analysis of the film showed that the weight ratio of lipid to protein of this surfactant film and its content of surface active substances were higher than those of lung wash. It was found that the wettability of the surfactant film could be simulated by a Dipalmitoyl lecithin and albumin film. When the surfactant film was transferred at condensed state (one of low air-lung-wash surface tension), we found the film exhibited a low critical surface tension which indicates the dominance of the lipid in the outer most layer of the film. On the other hand, insignificant amount of lipid was found in the film transferred at expanded state (one of high surface tension) and its surface behavior was shown to be similar to that of a protein film.