Image of NucBlue® Fixed Cell ReadyProbes® Reagent packaging

Nuclear stain for fixed cells

NucBlue Fixed Cell ReadyProbes Reagent is a bright blue cell-impermeant nuclear stain for fixed cells. It is useful to distinguish the condensed nuclei of apoptotic cells. It is also suitable for staining nuclei in fixed-cell preparations and tissue sections.

This protocol can be used for:

  • Nuclear staining to identify nuclear condensation in apoptotic cells using fluorescence microscopy

This protocol should not be used for:

  • Flow cytometry

You will need the following for this protocol:


Labeling fixed cells

First, fix and permeabilize cultured cells with a protocol appropriate for your sample.

1. Wash the cells 1–3 times in PBS as needed.
2. Add two drops of NucBlue Fixed Cell ReadyProbes Reagent per milliliter of medium.
3. Incubate for 5 minutes at 20–25°C.
4. Image the cells.
Spectral information and storage
Excitation/Emission (nm)360/460
Standard filter setDAPI
Storage conditionsRoom temperature



Protocol tips

fixed U2OS cell staining
Fixed U2OS cell staining. U2OS cells were fixed and permeabilized using the Image-iT Fixation/Permeabilization Kit. Cells were then with NucBlue Fixed Cell ReadyProbes Reagent for 15 minutes and imaged.