Molecular rheometry: Direct determination of viscosity in Lo and Ld lipid phases via fluorescence lifetime imaging

Yilei Wu, Martin Štefl, Agnieszka Olzyńska, Martin Hof, Gokhan Yahioglu, Philip Yip, Duncan R. Casey, Oscar Ces, Jana Humpolíčková*, Marina K. Kuimova

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

96 Citations (Scopus)
385 Downloads (Pure)

Abstract

Understanding of cellular regulatory pathways that involve lipid membranes requires the detailed knowledge of their physical state and structure. However, mapping the viscosity and diffusion in the membranes of complex composition is currently a non-trivial technical challenge. We report fluorescence lifetime spectroscopy and imaging (FLIM) of a meso-substituted BODIPY molecular rotor localised in the leaflet of model membranes of various lipid compositions. We prepare large and giant unilamellar vesicles (LUVs and GUVs) containing phosphatidylcholine (PC) lipids and demonstrate that recording the fluorescence lifetime of the rotor allows us to directly detect the viscosity of the membrane leaflet and to monitor the influence of cholesterol on membrane viscosity in binary and ternary lipid mixtures. In phase-separated 1,2-dioleoyl-sn-glycero-3-phosphocholine-cholesterol-sphingomyelin GUVs we visualise individual liquid ordered (Lo) and liquid disordered (Ld) domains using FLIM and assign specific microscopic viscosities to each domain. Our study showcases the power of FLIM with molecular rotors to image microviscosity of heterogeneous microenvironments in complex biological systems, including membrane-localised lipid rafts.

Original languageEnglish
Pages (from-to)14986-14993
Number of pages8
JournalPhysical Chemistry Chemical Physics
Volume15
Issue number36
Early online date9 Jul 2013
DOIs
Publication statusPublished - 28 Sep 2013

Keywords

  • Lipids
  • Molecular Structure
  • Rheology
  • Spectrometry, Fluorescence
  • Viscosity
  • Journal Article
  • Research Support, Non-U.S. Gov't

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