A near-field microscopy study of submicron domain structure in a model lung surfactant monolayer.
The submicron domain structure of coexisting liquid condensed (LC) and liquid expanded (LE) phases in monolayers composed of palmitic acid and 20 wt% of a lung surfactant protein B fragment has been investigated. Near-field microscopy was used to simultaneously measure topography and fluorescence images of monolayers that were prepared at a surface pressure of 15 mN/m and a temperature of 22 degrees C. The use of a fluorescently tagged peptide allowed for unambiguous determination of the peptide location in the two-component system. The LC and LE phases in the monolayers are measured on the submicron length scale. A 6-11 A height difference between the LC and LE phases was evident in the height images. Gradual transitions between the LC and LE domains were observed across a 1.3 microm length scale in the near-field fluorescence images, but were significantly sharper in the simultaneously collected topography images and in the separately measured AFM images. These results may reflect the occurrence of peptide encroachment into the LC domains.
Flanders
Bret N
BN
Department of Chemistry, The University of Kansas, Lawrence 66045, USA.
Dunn
Robert C
RC
D006801:Humans; D007231:Infant, Newborn; D008853:Microscopy / Q000295:instrumentation / Q000379:methods*; D019308:Palmitic Acid / Q000138:chemical synthesis / Q000737:chemistry; D011510:Proteolipids / Q000138:chemical synthesis / Q000737:chemistry* / Q000648:ultrastructure*; D011663:Pulmonary Surfactants / Q000138:chemical synthesis / Q000737:chemistry* / Q000648:ultrastructure*; D012127:Respiratory Distress Syndrome, Newborn / Q000503:physiopathology
D011510:Proteolipids; D011663:Pulmonary Surfactants; D019308:Palmitic Acid