Membrane integrity–based viability assay

NucRed® Dead 647 ReadyProbes® Reagent is a cell-impermeant stain that emits bright far-red fluorescence when bound to DNA. Since this reagent stains cells that lack plasma membrane integrity, it is extremely useful to measure viability and to measure cytotoxicity in kinetic live-cell assays. NucRed® Dead 647 reagent is also suitable for staining nuclei in fixed-cell preparations and tissue sections.

This protocol can be used for:

  • Identifying dead cells using a fluorescence microscope

This protocol should not be used for:

  • Flow cytometry

You will need the following for this protocol:



1. Culture cells in appropriate medium and vessel for microscopy


2. Add 2 drops NucRed® Dead 647 reagent per milliliter of medium to label cells


3. Incubate 5–15 minutes


4. Image cells

Spectral information and storage

  NucRed® Dead 647 ReadyProbes® Reagent
Excitation/Emission 642/661 nm
Standard filter set Cy®5
EVOS® Light Cube Cy®5
Storage conditions Room temperature

 Protocol tips


Tubulin and nuclear staining in HeLa cells. HeLa cells were fixed and permeabilized and stained for tubulin (biotinylated mouse anti-a-tubulin mouse monoclonal antibody followed by an Alexa Fluor 488 goat anti-mouse secondary antibody and counter-stained with NucRed Dead 647 ReadyProbes reagent.