Morphology of phase coexistence in a lung surfactant monolayer
Surfactant molecules coat the alveolar surfaces in all mammalian lungs and facilitate breathing by reducing surface tension. This micrograph shows the patterns formed in a lung surfactant monolayer at coexistence between liquid-like (bright) and a solid-like (dark) phases.
This fluorescence micrograph shows a monolayer of the pulmonary surfactant dipalmitoylphosphatidylcholine (DPPC) doped with a fluorescently labeled lipid. The fluorescent molecule is expelled from the condensed phase of DPPC and thus the liquid expanded phase appears bright. In a Langmuir trough, the DPPC monolayer is compressed until condensed domains nucleate and grow, forming the patterns shown. Brightness and contrast in the image have been altered for aesthetic purposes.