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
EVOS® Light CubeDAPI
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.