Lipid vesicle composition influences the incorporation and fluorescence properties of the lipophilic sulphonated carbocyanine dye SP-DiO
Journal article, 2020

Lipophilic carbocyanine dyes are widely used as fluorescent cell membrane probes in studies ranging from biophysics to cell biology. While they are extremely useful for qualitative observation of lipid structures, a major problem impairing quantitative studies is that the chemical environment of the lipid bilayer affects both the dye's insertion efficiency and photophysical properties. We present a systematic investigation of the sulphonated carbocyanine dye 3,3′-dioctadecyl-5,5′-di(4-sulfophenyl) (SP-DiO) and demonstrate how its insertion efficiency into pre-formed lipid bilayers and its photophysical properties therein determine its apparent fluorescence intensity in different lipid environments. For this purpose, we use large unilamellar vesicles (LUVs) made of lipids with distinct chain unsaturation, acyl chain length, head group charge, and with variation in membrane cholesterol content as models. Using a combination of absorbance, fluorescence emission, and fluorescence lifetime measurements we reveal that SP-DiO incorporates more efficiently into liquid disordered phases compared to gel phases. Moreover, incorporation into the latter phase is most efficient when the mismatch between the length of the lipid and dye hydrocarbon chains is small. Furthermore, SP-DiO incorporation is less efficient in LUVs composed of negatively charged lipids. Lastly, when cholesterol was included in the LUV membranes, we observed significant spectral shifts, consistent with dye aggregation. Taken together, our study highlights the complex interplay between membrane composition and labeling efficiency with lipophilic dyes and advocates for careful assessment of fluorescence data when attempting a quantitative analysis of fluorescence data with such molecules.


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Chalmers, Biology and Biological Engineering, Chemical Biology

[Person a0cb3f91-270b-4496-9925-ca2352257cb6 not found]

Chalmers, Physics, Biological Physics

[Person 1b6f57b3-dccf-43dc-a24b-14db0c3520c5 not found]

Umeå University

[Person 286960a9-59f4-4be9-a34f-69b11c8bd850 not found]

Chalmers, Chemistry and Chemical Engineering, Chemistry and Biochemistry

[Person fdbca724-d001-4f67-9e5f-c6f1f7c84899 not found]

Chalmers, Biology and Biological Engineering, Chemical Biology

[Person a21be298-7644-40f8-889e-386dab5f44a1 not found]

Chalmers, Biology and Biological Engineering, Chemical Biology

[Person 93c4ab4f-bbb1-46bf-9382-88c05a4845b7 not found]

Umeå University

Physical Chemistry Chemical Physics

1463-9076 (ISSN) 1463-9084 (eISSN)

Vol. 22 16 8781-8790

Vad karaktäriserar en toxisk amyloid oligomer?

Swedish Research Council (VR), 2017-01-01 -- 2020-12-31.

Areas of Advance

Nanoscience and Nanotechnology (SO 2010-2017, EI 2018-)

Life Science Engineering (2010-2018)

Materials Science

Subject Categories

Physical Chemistry

Other Chemistry Topics






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Latest update

6/3/2020 1