I was reading about voltage sensitive dyes. I found that DiSBAC2(3), if used as an individual dye, it enters the cell and binds to the intracellular proteins or membranes https://www.thermofisher.com/order/catalog/product/B413.
If DiSBAC2(3) is used as a part of FRET along with CC2-DMPE donor, it stay inside the plasma membrane https://www.thermofisher.com/order/catalog/product/K1021
I am sure that I am missing something here. Can anyone please explain this?
From the Thermo-Fisher web sites you mentioned:
"When the cell interior has a relatively negative potential, the oxonol dye will bind to the exterior of the cell membrane, resulting in efficient FRET. When the cell interior has a relatively positive potential, however, the oxonol dye will bind to the interior of the cell membrane, thus separating the FRET pair and disrupting FRET."
"The slow-response potential-sensitive probe, DiSBAC2(3) can enter depolarized cells where it binds to intracellular proteins or membrane and exhibits enhanced fluorescence and a red spectral shift. Increased depolarization results in additional influx of the anionic dye and an increase in fluorescence."
The membrane potential (polarization) seems to be the important factor that determines the extent to which the compound enters the cell, with depolarization (no membrane potential) favoring entry, but the presence of a membrane potential favoring the compound remaining bound to the membrane.
Thanks for replying Adam. However, as it is said about DiSBAC2(3) that "Increased depolarization results in additional influx of the anionic dye and an increase in fluorescence", means that the cells already have a membrane potential but still there is an influx of dyes in the cells, which does not support the theory that if the cells have a potential difference then the dyes will stay at the plasma membrane.
G'day Anjul -- Here is a complication which may be relevant ... is the dye usually ionised or not? What is its pK? The unionised free acid is [this is an estimate using the Hanch and Leo system] lipophilic, whereas the anion is hydrophilic. RWH.
Hi Richard. I think that the dyes are unionized. I do not know its pKa. Thanks for replying.
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