I used Image-iT FX Signal Enhancer solution to get rid of nonspecific nuclear labeling with Alexa Fluor 568 secondary antibody, but I also saw a significant reduction in my specific mitochondrial antibody labeling. Why is this and what can I do?
The Image-iT FX Signal Enhancer reduces non-specific binding of dye conjugates by blocking positively-charged areas of cells or tissues that attract negatively-charged dyes. In cells after fixation, some positively-charged structures are the nuclei and mitochondria. Thus, you would expect to see a reduction in both mitochondrial and nuclear signal. The lower signal you see afterward is the specific mitochondrial signal; the fluorescence that was lost was the non-specific labeling.
Find additional tips, troubleshooting help, and resources within our Cell Analysis Support Center.
Can I use the Image-iT FX Signal Enhancer instead of my normal blocking solution (BSA or serum)?
No. Image-iT FX Signal Enhancer is not a protein blocker, like BSA, normal serum, or other commercial antibody blockers. Use it as a separate step to block non-specific charge-based binding of dyes to cellular components.
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I am labeling fixed and permeabilized cultured cells with an Alexa Fluor secondary antibody. My secondary-only control is showing nuclear and mitochondrial labeling, even though I did a thorough protein blocking and tried a concentration range. What can be done to minimize this non-specific binding?
This is most likely charge-based binding due to interactions of the charge on the dyes with cellular components of opposite charge. This can be blocked by using the Image-iT FX Signal Enhancer Solution which eliminates non-specific binding due to charge. The Signal Enhancer is applied as a pre-blocking step and your regular blocking regimen should be used to limit non-specific binding due to protein-protein interactions. Signal Enhancer cannot be used on live cells.
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Can I use the ReadyProbes reagents for flow cytometry?
This is not recommended. The ReadyProbes reagents were developed for imaging applications whereas the Ready Flow reagents were optimized for flow cytometry.
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I am observing high background when I analyze my click-labeled samples. What is causing this and what can I do to reduce the background?
The click reaction is very selective between an azide and alkyne. No other side reactions are possible in a biological system. Any non-specific background is due to non-covalent binding of the dye to various cellular components. The Select FX Signal Enhancer is not effective at reducing non-specific charge-based binding of dyes following the click reaction; we do not recommend its use with the Click-iT detection reagents. The best method to reduce background is to increase the number of BSA washes. You should always do a no-dye or no-click reaction control under the same processing and detection conditions to verify that the background is actually due to the dye and not autofluorescence. You can also perform the complete click reaction on a carrier solvent-only, no EdU or no-EU control to verify the specificity of the click reaction signal.
Find additional tips, troubleshooting help, and resources within our Cell Viability, Proliferation, Cryopreservation, and Apoptosis Support Center.