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An's Project Page |
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Intern: An Ngo, University of Pittsburg
Mentor: Dr. Heidi Warriner
Faculty Supervisor: Dr. Joe Zasadzinski
Department: Chemical Engineering |
COLLAPSE STRUCTURES OF LUNG SURFACTANT PHOSPHOLIPID
Lung surfactant (LS) is a mixture of lipids and proteins that forms a monolayer coating the alveoli of the lungs. During exhalation, LS is in the "collapsed" phase, forming three-dimensional multilayers or folded structures, and reducing the surface tension of the alveolar surface to its lowest point (zero). This decrease in surface tension prevents the
alveoli from collapsing and reduces the work needed for reinflation. The structure of the LS layer at collapse determines its ability to respread, upon inhalation, to repeat the process. Collapse structures of DPPG, a lipid component of LS, were investigated with Brewster angle microscopy (BAM) and fluorescence microscopy (FM). The DPPG was spread on a layer of water and compressed with a Langmuir trough to mimic the expansion and compression of the alveolar surface during breathing. Surface pressure (the amount by which surface tension is lowered) was measured using a Wilhelmy plate attached to a pressure sensor made by R & K. It appears that the DPPG forms collapse induced fractures that do not respread upon reexpansion. Previous FM investigations suggest that the addition of surfactant protein SP-B facilitates respreading by allowing the DPPG monolayer to remain more fluid during collapse. Further studies seek to elucidate the role of SP-B by imaging with BAM.
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