Critical density fluctuations in lipid bilayers detected by fluorescence lifetime heterogeneity

A. Ruggiero, B. Hudson

Research output: Contribution to journalArticlepeer-review

61 Scopus citations


The heterogeneity of the decay of the fluorescence of transparinaric acid in single-component lipid bilayers at temperatures above their gel/liquid crystalline phase transition is shown to be due to the presence of regions of higher local density and higher acyl chain order than the predominant fluid regions. This conclusion is based on selective excitation behavior and the observation of time-resolved fluorescence anisotropies that increase at long times. The fractional amplitude of the long lifetime component of the fluorescence shows a temperature variation that conforms to conventional descriptions of critical behavior. The critical exponent extracted from this variation is 1.1, close to the value of 1.0 that describes ultrasonic data. We therefore conclude that liquid crystalline lipid bilayers exhibit critical behavior with significant density and order fluctuations. This behavior must be taken into account in the interpretation of fluorescence and other spectroscopic measurements of the properties of bilayers.

Original languageEnglish (US)
Pages (from-to)1111-1124
Number of pages14
JournalBiophysical Journal
Issue number6
StatePublished - 1989
Externally publishedYes

ASJC Scopus subject areas

  • Biophysics


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