I am seeing high background outside of my neuronal cells when using membrane potential indicators. What can I do to reduce background?
If you use our FluoVolt Membrane Potential Kit (Cat. No. F10488), the kit provides a background suppressor to reduce this problem. For other indicators, consider the use of BackDrop Background Suppressor (Cat no. R37603, B10511, and B10512).
Find additional tips, troubleshooting help, and resources within our Cell Analysis Support Center.
I stained my cells with a lipophilic cyanine dye, like DiI, but the signal was lost when I tried to follow up with antibody labeling. Why?
Since these dyes insert into lipid membranes, any disruption of the membranes leads to loss of the dye. This includes permeabilization with detergents like Triton X-100 or organic solvents like methanol. Permeabilization is necessary for intracellular antibody labeling, leading to loss of the dye. Instead, a reactive dye such as CFDA SE should be used to allow for covalent attachment to cellular components, thus providing for better retention upon fixation and permeabilization.
Find additional tips, troubleshooting help, and resources within our Cell Analysis Support Center.
What is the difference between fast and slow-response membrane potential probes?
Molecules that change their structure in response to the surrounding electric field can function as fast-response probes for the detection of transient (millisecond) potential changes. Slow-response dyes function by entering depolarized cells and binding to proteins or membranes. Increased depolarization results in additional dye influx and an increase in fluorescence, while hyperpolarization is indicated by a decrease in fluorescence. Fast-response probes are commonly used to image electrical activity from intact heart tissues or measure membrane potential changes in response to pharmacological stimuli. Slow-responding probes are often used to explore mitochondrial function and cell viability.
Find additional tips, troubleshooting help, and resources within our Cell Analysis Support Center.
What type of membrane potential indicators do you offer and how should I choose one for my experiment?
A membrane potential indicator selection guide can be found here (https://www.thermofisher.com/us/en/home/life-science/cell-analysis/cell-viability-and-regulation/ion-indicators/membrane-potential-indicators.html).
Find additional tips, troubleshooting help, and resources within our Cell Analysis Support Center.
How long does it take for lipophlic tracers to transport along the membrane? How much faster are the FAST lipophilic dyes?
The transport is fairly slow, around 6 mm/day in live tissue and slower in fixed tissue, so diffusion of lipophilic carbocyanine tracers from the point of their application to the terminus of a neuron can take several days to weeks The FAST DiO and DiI analogs (which have unsaturated alkyl tails) can improve transport rate by around 50%.
Find additional tips, troubleshooting help, and resources within our Cell Analysis Support Center.
