Critical fluctuations in domain-forming lipid mixtures
- 6 November 2007
- journal article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences of the United States of America
- Vol. 104 (45), 17650-17655
- https://doi.org/10.1073/pnas.0703513104
Abstract
Critical fluctuations are investigated in lipid membranes near miscibility critical points in bilayers composed of dioleoylphosphatidylcholine, chain perdeuterated dipalmitoylphosphatidylcholine, and cholesterol. Phase boundaries are mapped over the temperature range from 10 degrees C to 60 degrees C by deuterium NMR. Tie-lines and three-phase triangles are evaluated across two-phase and three-phase regions, respectively. In addition, a line of miscibility critical points is identified. NMR resonances are broadened in the vicinity of critical points, and broadening is attributed to increased transverse relaxation rates arising from modulation of chain order with correlation times on a microsecond time scale. We conclude that spectral broadening arises from composition fluctuations in the membrane plane with dimensions of <50 nm and speculate that similar fluctuations are commonly found in cholesterol-containing membranes.Keywords
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