Image of NucBlue® Fixed Cell ReadyProbes® Reagent packaging

Nuclear stain for live cells

NucBlue Live reagent (Hoechst 33342 dye) stains the nuclei of all cells. NucBlue Live reagent is frequently used to distinguish condensed nuclei in apoptotic cells.

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:


1. Culture cells in an appropriate medium and vessel for fluorescence microscopy.
2. Add two drops of NucBlue Live ReadyProbes Reagent per milliliter of medium.
3. Incubate for 20 minutes, protected from light.
4. Image the cells.
Spectral information and storage
Excitation/Emission (nm)360/460
Standard filter setDAPI
Storage conditionsRoom temperature


Protocol tips

U2OS live-cell staining
U2OS live-cell staining. Live U2OS cells were imaged 15 minutes following staining with NucBlue Live ReadyProbes Reagent.