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Jahl PE, Parthasarathy R. Assessing the use of ellipsoidal microparticles for determining lipid membrane viscosity. Biophys J. 2021;doi: 10.1016/j.bpj.2021.11.020.
Jahl, P. E., & Parthasarathy, R. (2021). Assessing the use of ellipsoidal microparticles for determining lipid membrane viscosity. Biophysical journal, . https://doi.org/10.1016/j.bpj.2021.11.020
Jahl, Philip E, and Parthasarathy, Raghuveer. "Assessing the use of ellipsoidal microparticles for determining lipid membrane viscosity." Biophysical journal vol. (2021). doi: https://doi.org/10.1016/j.bpj.2021.11.020
Jahl PE, Parthasarathy R. Assessing the use of ellipsoidal microparticles for determining lipid membrane viscosity. Biophys J. 2021 Nov 18; doi: 10.1016/j.bpj.2021.11.020. Epub 2021 Nov 18. PMID: 34800470.
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Biophys J. 2021 Nov 18; doi: 10.1016/j.bpj.2021.11.020. Epub 2021 Nov 18.

Assessing the use of ellipsoidal microparticles for determining lipid membrane viscosity.

Biophysical journal

Philip E Jahl, Raghuveer Parthasarathy

Affiliations

  1. Materials Science Institute and Department of Physics, The University of Oregon, Eugene, OR, USA.
  2. Materials Science Institute and Department of Physics, The University of Oregon, Eugene, OR, USA. Electronic address: [email protected].

PMID: 34800470 DOI: 10.1016/j.bpj.2021.11.020

Abstract

The viscosity of lipid membranes sets the timescales of membrane-associated motions, whether driven or diffusive, and therefore influences the dynamics of a wide range of cellular processes. Techniques to measure membrane viscosity remain sparse, however, and reported measurements to date, even of similar systems, give viscosity values that span orders of magnitude. To address this, we improve a method based on measuring both the rotational and translational diffusion of membrane-anchored microparticles and apply this approach and one based on tracking the motion of phase-separated lipid domains to the same system of phase-separated giant vesicles. We find good agreement between the two methods, with inferred viscosities within a factor of two of each other. Our single-particle tracking technique uses ellipsoidal microparticles, and we show that the extraction of physically meaningful viscosity values from their motion requires consideration of their anisotropic shape. The validation of our method on phase-separated membranes makes possible its application to other systems, which we demonstrate by measuring the viscosity of bilayers composed of lipids with different chain lengths ranging from 14 to 20 carbon atoms, revealing a very weak dependence of two-dimensional viscosity on lipid size. The experimental and analysis methods described here should be generally applicable to a variety of membrane systems, both reconstituted and cellular.

Copyright © 2021 Biophysical Society. Published by Elsevier Inc. All rights reserved.

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