Lipid monolayer states and their relationships to bilayers.

Journal Article (Journal Article)

Uncommon methods of formation and analysis of lipid monolayers have enabled the recognition of several monolayer states and the identification of that in which molecular organization corresponds closely to that of the bilayer. Monolayers were formed by continuously adding a solution of phospholipid [dimyristoyl phosphatidylcholine in hexane/ethanol, 9:1 (vol/vol)] to the air/water interface of a constant-area trough. This procedure generates unconventional surface pressure (pi)-surface concentration (gamma) isotherms, which for liquid-crystalline monolayers consist of straight lines with three prominent intersections, two of which are not apparent in conventional pi-A isotherms. The regions of linear change of pi are explicable in terms of the area dependence of alkyl chain entropy. The two breaks at lower pi delimit states in which both chains lie parallel to the surface. The third occurs at collapse, which corresponds to a true equilibrium for unstressed liposomes. Mechanical and thermodynamic properties of bilayers, particularly phase-transition parameters, correspond closely to those of monolayers with which they are in equilibrium.

Full Text

Duke Authors

Cited Authors

  • MacDonald, RC; Simon, SA

Published Date

  • June 1987

Published In

Volume / Issue

  • 84 / 12

Start / End Page

  • 4089 - 4093

PubMed ID

  • 3473494

Pubmed Central ID

  • PMC305028

International Standard Serial Number (ISSN)

  • 0027-8424

Digital Object Identifier (DOI)

  • 10.1073/pnas.84.12.4089


  • eng

Conference Location

  • United States