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Fixable Viability Stains for Flow Cytometry & Microscopy

A plethora of dye colors designed for dead cell labeling in flow cytometry
Covalent labeling withstands fixation and permeabilization, with no loss of signal
Several combination staining kits are available with all-yeast stains combined with Live-or-Dye™ dead cell stains
Spectral flow cytometry
Dyes that can be spectrally unmixed on the Cytek® Aurora spectral cytometer
Dyes validated as dead cell stains in fluorescence microscopy
A DNA-binding, fixable dead cell stain for flow or microscopy


Covalent labeling of dead cells for flow or microscopy

Live-or-Dye™ Fixable Viability Stains are cell membrane impermeant amine-reactive dyes. The dyes enter dead cells that have compromised membrane integrity and covalently label free amines on intracellular proteins. On live cells, the dyes react with surface proteins, but these are much less abundant than intracellular proteins, resulting in low staining levels compared to dead cells.

Live-or-Dye™ labeling is extremely stable, allowing the cells to be fixed and permeabilized without loss of fluorescence or dye transfer between cells. The staining protocol has been optimized to maximize live/dead discrimination with minimal live cell staining, in order to prevent interference with immunostaining. Biotium offers a large and growing selection of bright and photostable Live-or-Dye™ stains for maximal flexibility in multi-color analysis.

In addition to standard flow cytometry, many of our dyes have been validated in spectral flow cytometry on the Cytek® Aurora instrument.

We also offer Live-or-Dye NucFix™ Red, a unique fixable nuclear-specific dead cell stain.

Live-or-Dye fixable viability stains
Figure 1. Principle of Live-or-Dye discrimination of live and dead cells.


Live-or-Dye™ Fixable Viability Staining Kits are designed for discrimination between live and dead cells during flow cytometry. Live/dead stains are useful probes to include when analyzing cell surface protein expression by flow cytometry, because they allow intracellular fluorescence signal from dead cells with permeable plasma membranes to be excluded from analysis.

The Live-Or-Dye™ Fixable Viability Staining Kits were designed to give a great separation between live and dead cell signals, in order to make it easy to exclude dead cells from your analysis (Fig. 1).

Live-or-Dye™ kits are available with 12 bright and stable dye colors for multichannel flow cytometry.


Fixability is an important feature of a dead cell stain. The ability of a stain to withstand both fixation and permeabilization allows the dye to be combined with intracellular flow cytometry staining protocols or immunofluorescent microscopy experiments, among other applications.

Live-or-Dye™ Fixable Viability Staining Kits have superior fixability and stable staining (Fig. 2). Our bright and photostable dyes allow samples to be fixed, permeabilized, and stored (protected from light) without loss of signal.

Figure 2. A mixture of live and dead Jurkat cells were stained with Live-or-Dye™ 405/452. One sample was left unfixed (lower, light cyan plot), and another sample was fixed in 2% formaldehyde and permeabilized with 0.1% Triton® X-100 (upper, dark cyan plot). No loss of signal is seen in the dead cells. No transfer of dye to live cells is seen.


It is often very useful to identify dead cells for microscopic analysis as well, particularly when performing live-cell imaging experiments. In microscopy, live/dead stains allow unambiguous visual discrimination of dead cells. Live-or-Dye™ Fixable Viability Staining Kits work just as well for microscopy as they do for flow cytometry: they are bright and photo-stable dyes, with negligible signal in live cells and strong signal in dead cells.

Four stains have been validated for fluorescence microscopy: Live-or-Dye™ 488/515, 568/583, 594/614, & 640/662. The other  dyes are expected to work as well, as long as the microscope has the appropriate excitation and emission settings.

Figure 3. Ethanol-treated HeLa cells stained with Live-or-Dye™ Fixable Dead Cell Stains. Dead cells stain brightly with Live-or-Dye™, while live cells show minimal staining. Nuclei are stained with Hoechst (blue).


Live-or-Dye NucFix™ Red is a unique, cell membrane impermeable dye that specifically stains the nuclei of dead cells.

Unlike other commonly used nuclear stains such as propidium iodide (PI) or DRAQ7™, Live-or-Dye NucFix™ labeling is covalent, so the dye doesn’t transfer between cells after fixation. Live-or-Dye NucFix™ Red can be used for flow cytometry or fluorescence microscopy.

live or dye nucfix red
Figure 4. Discrimination of live and dead cells using Live-or-Dye NucFix™ Red Fixable Viability Stain. A. Flow cytometry of live (open peak) or heat-killed (solid peak) Jurkat cells stained with Live-or-Dye NucFix™ Red. B. Ethanol-treated HeLa cells stained with NucFix™ Red. Killed cells show bright red nuclear staining, compared to no staining seen in live cells. Nuclei are stained with Hoechst (blue).


For yeast and fungal cells we have developed a series of staining kits that combine the dead cell-specific Live-or-Dye™  stains with all-cell stains designed with yeast properties in mind.

The Yeast Live-or-Dye™ Live/Dead Staining Kit combines a cell-permeant green dye, Thiazole Orange, which concentrates in the nucleus of live cells, with Live-or-Dye™ 568/583 (Fig. 5). Co-staining with the two dyes allows live/dead discrimination of yeast by fluorescence microscopy or flow cytometry.

The Yeast Viability Staining Kits take advantage of the unique fungal cell wall, by combining a Live-or-Dye™ dead cell stain with a fluorescent conjugate of the cell wall probe Concanavalin A (Con A) (Fig. 6). These kits are available in 3 color combinations for maximum experimental flexibility.

Yeast Live-or-Dye Fixable Live/Dead Staining Kit
Figure 5. In the Yeast Live-or-Dye™ Fixable Live/Dead Staining Kit, Thiazole Orange gives nuclear-concentrated staining in all cells (green), while Live-or-Dye™ 568/583 specifically stains dead cells red (yellow in the merge).
Yeast Viability Staining Kit
Figure 6. The Yeast Viability Staining Kit (Red/Far-Red) contains CF®640R Con A, which binds to the cell wall of all yeast (blue), with Live-or-Dye™ 568/583, which stains dead cells red.


Catalog No.

Viability Dye

Laser line

Emission filter

Abs/Em Max


32002, 32002-TLive-or-Dye™ 350/448355 nmDAPI or Violet355/450 nmFlow Cytometry
32014,32014-TLive-or-Dye™ 375/600355 or 405 nmSpectral Scan373/595 nmSpectral Cytometry
32003, 32003-TLive-or-Dye™ 405/452405 nmPacific Blue®416/452 nmFlow Cytometry
32009, 32009-TLive-or-Dye™ 405/545405 nmAmCyan413/547 nmFlow Cytometry
32004, 32004-TLive-or-Dye™ 488/515488 nmFITC490/516 nmFlow Cytometry,
32012, 32012-TLive-or-Dye™ 510/550488 nmSpectral scan516/549 nmSpectral Cytometry
32005, 32005-TLive-or-Dye™ 568/583488 or 561 nmPE562/584 nmFlow Cytometry,
32006, 32006-TLive-or-Dye™ 594/614488 or 561 nmPE-Texas Red®593/615 nmFlow Cytometry,
32015, 32015-TLive-or-Dye™ 615/740633 nmSpectral scan612/744 nmSpectral Cytometry
32007, 32007-TLive-or-Dye™ 640/662633 or 640 nmAPC642/663 nmFlow Cytometry, Microscopy
32013, 32013-TLive-or-Dye™ 665/685633 or 640 nmSpectral scan667/685 nmSpectral Cytometry
32008, 32008-TLive-or-Dye™ 750/777633 or 640 nmAPC-Cy®7755/779 nmFlow Cytometry
32011, 32011-TLive-or-Dye™ 787/808785 or 808 nmAPC-Cy®7 or IR800783/808 nmFlow Cytometry
32010, 32010-TLive-or-Dye NucFix™ Red488 or 532 nmPE-Texas Red®520/593 nmFlow Cytometry,

Yeast-Specific Fixable Viability Staining Kits

Catalog No.Kit NameLive-or-Dye™ ColorOther Dye
31064 Yeast Live-or-Dye™ Fixable Live/Dead Staining KitLive-or-Dye™ 568/583 (stains dead cells red)Thiazole Orange (stains all cells green)
31063-1 Yeast Viability Staining Kit (Green/Red)Live-or-Dye™ 594/614 (stains dead cells red)CF®488A ConA (stains all cell walls green)
31063-2Yeast Viability Staining Kit (Red/Blue)Live-or-Dye™ 405/452 (stains dead cells blue)CF®594 ConA (stains all cell walls red)
31063-3Yeast Viability Staining Kit (Red/Far-Red)Live-or-Dye™ 568/583 (stains dead cells red)CF®640R ConA (stains all cell walls far-red)

Draq7 is a trademark of Biostatus, Ltd. Texas Red and Pacific Blue are registered trademarks of Thermo Fisher Scientific. Cy dye is a registered trademark of GE Healthcare.

Live-or-Dye™ Fixable Viability Staining Kits

From: $65 Sizes: 50 assays, 200 assays, 250 assaysCatalog #: 32016, 32017, 32002-T, 32014-T, 32003-T, 32009-T, 32004-T, 32012-T, 32015-T, 32005-T, 32007-T, 32006-T, 32013-T, 32008-T, 32011-T, 32002, 32014, 32003, 32009, 32004, 32012, 32005, 32006, 32015, 32007, 32013, 32008, - 32011View allHide

Live-or-Dye NucFix™ Red Staining Kit

From: $62 Sizes: 50 assays, 200 assaysCatalog #: 32010, - 32010-TView allHide

Yeast Live-or-Dye™ Fixable Live/Dead Staining Kit

From: $361 Sizes: 1,000 assaysCatalog #: 31064

Yeast Viability Staining Kit

From: $391 Sizes: 1,000 assaysCatalog #: 31063-1, 31063-2, - 31063-3View allHide