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Trans-Cis isomerization of lipophilic dyes probing membrane microviscosity in biological membranes and in live cells
KTH, School of Engineering Sciences (SCI), Applied Physics, Experimental Biomolecular Physics.
KTH, School of Engineering Sciences (SCI), Applied Physics, Experimental Biomolecular Physics.
KTH, School of Engineering Sciences (SCI), Applied Physics, Experimental Biomolecular Physics.
KTH, School of Engineering Sciences (SCI), Applied Physics, Experimental Biomolecular Physics.
2015 (English)In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 87, no 11, 5690-5697 p.Article in journal (Refereed) Published
Abstract [en]

Membrane environment and fluidity can modulate the dynamics and interactions of membrane proteins and can thereby strongly influence the function of cells and organisms in general. In this work, we demonstrate that trans-cis isomerization of lipophilic dyes is a useful parameter to monitor packaging and fluidity of biomembranes. Fluorescence fluctuations, generated by trans-cis isomerization of the thiocarbocyanine dye Merocyanine 540 (MC540), were first analyzed by fluorescence correlation spectroscopy (FCS) in different alcohol solutions. Similar isomerization kinetics of MC540 in lipid vesicles could then also be monitored, and the influence of lipid polarity, membrane curvature, and cholesterol content was investigated. While no influence of membrane curvature and lipid polarity could be observed, a clear decrease in the isomerization rates could be observed with increasing cholesterol contents in the vesicle membranes. Finally, procedures to spatially map photoinduced and thermal isomerization rates on live cells by transient state (TRAST) imaging were established. On the basis of these procedures, MC540 isomerization was studied on live MCF7 cells, and TRAST images of the cells at different temperatures were found to reliably detect differences in the isomerization parameters. Our studies indicate that trans-cis isomerization is a useful parameter for probing membrane dynamics and that the TRAST imaging technique can provide spatial maps of photoinduced isomerization as well as both photoinduced and thermal back-isomerization, resolving differences in local membrane microviscosity in live cells.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2015. Vol. 87, no 11, 5690-5697 p.
Keyword [en]
Biological membranes, Cells, Cholesterol, Cytology, Fluidity, Fluorescence, Fluorescence spectroscopy, Imaging techniques, Isomerization, Membranes, Proteins, Spectroscopic analysis, Fluorescence Correlation Spectroscopy, Fluorescence fluctuation, Isomerization kinetics, Merocyanine 540 (MC540), Photoinduced isomerization, Thermal back-isomerization, Thermal isomerizations, Trans-cis isomerization
National Category
Analytical Chemistry
Research subject
Biological Physics
URN: urn:nbn:se:kth:diva-170226DOI: 10.1021/acs.analchem.5b00863ISI: 000355779500036ScopusID: 2-s2.0-84930641310OAI: diva2:828439
EU, FP7, Seventh Framework Programme, FLUODIAMON 201 837Swedish Research Council, VR-NT 2012-3045Knut and Alice Wallenberg Foundation, KAW 2011.0218

QC 20150630

Available from: 2015-06-30 Created: 2015-06-29 Last updated: 2016-03-10Bibliographically approved

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Chmyrov, VolodymyrSpielmann, ThiemoHevekerl, HeikeWidengren, Jerker
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