Overview of LIVE/DEAD cell viability assays

Thermo Fisher Scientific LIVE/DEAD cell viability assays provide for easy and sensitive differentiation of live, dead, and cytotoxic populations using fluorescence microscopy, flow cytometry, or microplate readers. These fluorescent-based LIVE/DEAD assays can be used to evaluate viability in cellular populations, bacteria, fungi, and yeast. The fluorescent dyes used in these viability assays range from blue to near-IR emission. Some viability assays permit fixation, which enables intracellular staining and neutralization of pathogens.

LIVE/DEAD Cell Viability Assays selection guide

LIVE/DEAD cell viability kits offer 2- or 3-color discrimination of live from dead cell populations based on membrane integrity, esterase activity, metabolic activity, or structural segmentation.

Learn more about these LIVE/DEAD cell viability kits.

 Platform*Fluorescent dyesEx/Em (nm) **Fluorescent ColorCat. No.
LIVE/DEAD Viability/Cytotoxicity KitFC, FM, MCalcein AM
ethidium homodimer-1
494/517
517/617
Green (Live)
Red (Dead)
L3224
The LIVE/DEAD Viability/Cytotoxicity Assay Kit (Green/Deep Red)FM, MCalcein AM,  SYTOX Deep Red494/517
660/682
Green (Live)
Deep Red (Dead)
L32250
LIVE/DEAD Cell-Mediated Cytotoxicity Kit FC, FM, MDiOC19(3)
propidium iodide
484/501
536/617
Green (Live)
Red (Dead)
L7010
LIVE/DEAD Sperm Viability KitFC, FMSYBR 14 dye
propidium iodide
485/517
536/617
Green (Live)
Red (Dead)
L7011
LIVE/DEAD Reduced Biohazard Cell Viability Kit #1FC, FM, MSYTO 10 green ethidium homodimer-2484/505
535/624
Green (Live)
Red (Dead)
L7013
LIVE/DEAD Cell Viability Assay Kit, C12 Resazurin/SYTOX GreenFC, FM, MSYTOX Green dye
C12-resazurin
488/530
488/575
Green (Dead)
Red (Live)
L34951
LIVE/DEAD Violet Viability/Vitality KitFMCalcein violet AM
aqua-fluorescent reactive dye
400/452
367/528
Violet (Live)
Violet (Dead)
L34958
LIVE/DEAD Cell Imaging KitFMCalcein AM
BOBO-3 Iodide
488/515
570/602
Green (Live)
Red (Dead)
R37601
HCS LIVE/DEAD Green KitFM, MHoechst 33342
Image-iT DEAD Green
HCS NuclearMask Deep Red
350/461
488/515
638/686
Blue (DNA)
Green (Dead)
Red (Live)
H10290
*FC = flow cytometry; FM = fluorescence microscopy; M = microplate assay
**Ex=excitation; Em=emission

LIVE/DEAD kits for cellular viability

LIVE/DEAD cell viability kits offer 2- or 3-color discrimination of live from dead cell populations based on membrane integrity, esterase activity, metabolic activity, or structural segmentation. These viability kits been have optimized for use on fluorescence microscopy, flow cytometry, and microplate readers.

LIVE/DEAD Viability/Cytotoxicity Kit is a quick and easy 2-color viability assay based on membrane integrity and esterase activity (Figure 1). Plasma membrane integrity is determined by ethidium homodimer-1 which enters cells with compromised plasma membranes to bind DNA and emit a red fluorescence; live cells are identified by Calcein AM, a fluorogenic cell-permeant dye that is converted to a green fluorescence after interaction with intracellular esterases.

LIVE/DEAD Viability/Cytotoxicity Kit evaluates plasma membrane integrity and esterase activity

LIVE/DEAD Cell Viability Assay Kit evaluates plasma membrane integrity and metabolic activity

LIVE/DEAD Cell Viability Assay Kit, C12 Resazurin/SYTOX Green is a simple, 2-color viability assay to identify metabolically active cells from dead and damaged cells (Figure 2). In metabolically active cells, C12-resazurin is reduced to C12-resorufin to emit a red fluorescence. C12-resazurin is the lipophilic version of resazurin that is more permeable to live cells and the C12-resorufin product is better retained in cells. The SYTOX Green dye enters the compromised plasma membrane of dead and dying cells, and binds DNA, resulting in a green fluorescence. Cells that have undergone damage, will display a reduced red and green fluorescence.

Distinct green-fluorescent dead cells, red-fluorescent live cells, and double stained injured cells

Figure 2. LIVE/DEAD Cell Vitality Kit. Jurkat cells (T-cell leukemia, human) were induced with 10 μM camptothecin for 4 hours at 37°C, 5% CO2. The cells were incubated with the reagents in the LIVE/DEAD Cell Vitality Assay Kit and analyzed by flow cytometry. The dot plot of SYTOX Green fluorescence vs. resorufin fluorescence shows resolution of live, injured, and dead cell populations.

LIVE/DEAD kits for bacterial viability are convenient and easy-to-use 2-color fluorescent assays to discriminate between live and dead bacterial cell populations based on membrane integrity.

Learn more about these LIVE/DEAD bacterial viability kits.

 Platform*Fluorescent dyesEx/Em (nm) **Fluorescent ColorCat. No.
LIVE/DEAD BacLight Bacterial Viability KitFC, FM, MSYTO 9
propidium iodide
480/500
490/635
Green (Live)
Red (Dead)
L7007
LIVE/DEAD BacLight Bacterial Viability Kit, for microscopy & quantitative assaysFC, FM, MSYTO 9
propidium iodide
480/500
490/635
Green (Live)
Red (Dead)
L7012
LIVE/DEAD BacLight Bacterial Viability KitFC, FM, MSYTO 9
propidium iodide
480/500
490/635
Green (Live)
Red (Dead)
L13152
LIVE/DEAD BacLight Bacterial Viability and Counting KitFCSYTO 9
propidium iodide
485/498
535/617
Green (Live)
Red (Dead)
L34856
FilmTracer LIVE/DEAD Biofilm Viability KitFMSYTO 9
propidium iodide
482/500
490/635
Green (Live)
Red (Dead)
L10316
*FC = flow cytometry; FM = fluorescence microscopy; M = microplate assay
**Ex=excitation; Em=emission

LIVE/DEAD kits for bacterial viability

LIVE/DEAD kits for bacterial viability are convenient and easy-to-use 2-color fluorescent assays to discriminate between live and dead bacterial cell populations based on membrane integrity. These kits contain SYTO 9 green-fluorescent stain and PI red-fluorescent stain that differ in their ability to enter bacteria. When used alone, SYTO 9 will stain all bacteria in a population regardless of membrane integrity; however, PI will only enter bacteria with a compromised membrane causing reduced SYTO 9 fluorescence. With an optimized mixture, dead bacteria will fluoresce red, while live bacteria will fluoresce green. These assays have been optimized for use on fluorescence microscopy (Figure 3), flow cytometry (Figure 4), and microplate readers.

Learn more: bacterial viability assays for flow cytometry

Green-fluorescent live bacteria and red-fluorescent dead bacteria

Figure 3. LIVE/DEAD BacLight Bacterial Viability Kit.Micrococcus luteus and Bacillus cereus stained with the LIVE/DEAD BacLight Bacterial Viability Kit. When incubated with the SYTO 9 stain and the propidium iodide nucleic acid stain provided in this kit, live bacteria with intact cell membranes fluoresce green and dead bacteria with compromised membranes fluoresce red.

Figure 4. Analysis of bacterial cultures using the LIVE/DEAD BacLight Bacterial Viability and Counting Kit. Suspensions of live (untreated) and dead (alcohol-treated) Staphylococcus aureus (Panels A and C) and Escherichia coli (Panels B and D) were stained and analyzed by flow cytometry according to the LIVE/DEAD BacLight Bacterial Viability and Counting Kit protocol. Using green or red fluorescence versus side scatter cytogram (Panels A and B), the bacterial populations and the bead populations were gated (left and right boxes, respectively). Events in the bacteria region of each cytogram are also displayed in red fluorescence versus green fluorescence cytograms (Panels C and D). Live and dead bacteria/mL can be calculated from either the fluorescence versus side scatter cytogram or the green fluorescence versus red fluorescence cytogram, depending on which one shows the best separation of the live and dead populations. The position of the live and dead populations in these cytograms may be dependent on cell type and gram character. Some samples may exhibit events that fall outside the defined regions and should be evaluated appropriately (e.g., see Panel D).

LIVE/DEAD kits for fungi and yeast viability offer 2-color discrimination of live and dead fungal populations based on membrane integrity or metabolic activity and fungal cell wall labeling.

Learn more about these LIVE/DEAD fungi and yeast viability kits.

 Platform*Fluorescent dyesEx/Em (nm) **Fluorescent ColorCat. No.
LIVE/DEAD Yeast Viability KitFM, MFUN 1
Calcofluor White M2R
488/530
488/560-610
365/440
Green (All)
Red-orange (Live)
Blue (All)
L7009
LIVE/DEAD FungaLight Yeast Viability KitFCSYTO9 dye
propidium iodide
485/530
485/630
Green (Live)
Red (Dead)
L34952
*FC = flow cytometry; FM = fluorescence microscopy; M = microplate assay
**Ex=excitation; Em=emission

LIVE/DEAD Kits for fungi and yeast viability

LIVE/DEAD Yeast Viability Kits provide easy, reliable, and quantitative discrimination in pure or mixed cultures. Each kit offers 2-color discrimination based on membrane integrity or metabolic activity, and fungal cell wall labeling.

Learn more: yeast viability assays for flow cytometry

LIVE/DEAD Yeast Viability Kit evaluates metabolic activity

The Yeast Viability Kit (Figure 5) contains FUN 1 dye, that uses the plasma membrane integrity and metabolic activity of live populations to convert the yellow-green-fluorescent intracellular staining to red-orange intravacuolar structures, and Calcofluor White M2R which labels cell-wall chitin with a blue-fluorescence.

Yeast with yellow/green intracellular staining, red/orange intravacuolar structures, and blue cell wall chitin

Figure 5. LIVE/DEAD Yeast Viability Kit.Saccharomyces cerevisiae stained with the FUN 1 cell stain, which generates red-fluorescent intravacuolar structures, and with Calcofluor White M2R, a blue-fluorescent cell wall stain, both components of the LIVE/DEAD Yeast Viability Kit.

LIVE/DEAD FungaLight Yeast Viability Kit, for flow cytometry evaluates membrane integrity

The LIVE/DEAD FungaLight Yeast Viability Kit uses 2 nucleic acids stains - SYTO9 green-fluorescent stain and PI red-fluorescent stain (Figure 6). When used alone, SYTO 9 will stain all yeast in the population; while PI only enters yeast with a damaged membrane resulting in reduced SYTO 9 fluorescence. As a result, live yeast with uncompromised membrane will fluoresce green whereas dead yeast with compromised membrane will fluoresce red.

Forward and side scatter of the yeast population; and scatter plot with distinct green live and red dead yeast

Figure 6. Saccharomyces spp. cell suspensions stained with SYTO 9 dye and propidium iodide and analyzed using a BD FACSCalibur flow cytometry system (Becton Dickinson and Co.). Panel A shows the dot plot of forward scatter vs. side scatter of an untreated Saccharomyces culture, washed and stained with SYTO 9 dye and propidium iodide as described in the LIVE/DEAD FungaLight Yeast Viability Kit protocol. The region R1 contains particles of the appropriate size for yeast cells; the forward scatter trigger is set to exclude debris in the sample. Panel B shows the R1-gated staining pattern obtained following analysis of a sample of yeast containing a mixture of both live and heat-killed cells.

LIVE/DEAD cell viability kits offer 2- or 3-color discrimination of live from dead cell populations based on membrane integrity, esterase activity, metabolic activity, or structural segmentation.

Learn more about these LIVE/DEAD cell viability kits.

 Platform*Fluorescent dyesEx/Em (nm) **Fluorescent ColorCat. No.
LIVE/DEAD Viability/Cytotoxicity KitFC, FM, MCalcein AM
ethidium homodimer-1
494/517
517/617
Green (Live)
Red (Dead)
L3224
The LIVE/DEAD Viability/Cytotoxicity Assay Kit (Green/Deep Red)FM, MCalcein AM,  SYTOX Deep Red494/517
660/682
Green (Live)
Deep Red (Dead)
L32250
LIVE/DEAD Cell-Mediated Cytotoxicity Kit FC, FM, MDiOC19(3)
propidium iodide
484/501
536/617
Green (Live)
Red (Dead)
L7010
LIVE/DEAD Sperm Viability KitFC, FMSYBR 14 dye
propidium iodide
485/517
536/617
Green (Live)
Red (Dead)
L7011
LIVE/DEAD Reduced Biohazard Cell Viability Kit #1FC, FM, MSYTO 10 green ethidium homodimer-2484/505
535/624
Green (Live)
Red (Dead)
L7013
LIVE/DEAD Cell Viability Assay Kit, C12 Resazurin/SYTOX GreenFC, FM, MSYTOX Green dye
C12-resazurin
488/530
488/575
Green (Dead)
Red (Live)
L34951
LIVE/DEAD Violet Viability/Vitality KitFMCalcein violet AM
aqua-fluorescent reactive dye
400/452
367/528
Violet (Live)
Violet (Dead)
L34958
LIVE/DEAD Cell Imaging KitFMCalcein AM
BOBO-3 Iodide
488/515
570/602
Green (Live)
Red (Dead)
R37601
HCS LIVE/DEAD Green KitFM, MHoechst 33342
Image-iT DEAD Green
HCS NuclearMask Deep Red
350/461
488/515
638/686
Blue (DNA)
Green (Dead)
Red (Live)
H10290
*FC = flow cytometry; FM = fluorescence microscopy; M = microplate assay
**Ex=excitation; Em=emission

LIVE/DEAD kits for cellular viability

LIVE/DEAD cell viability kits offer 2- or 3-color discrimination of live from dead cell populations based on membrane integrity, esterase activity, metabolic activity, or structural segmentation. These viability kits been have optimized for use on fluorescence microscopy, flow cytometry, and microplate readers.

LIVE/DEAD Viability/Cytotoxicity Kit is a quick and easy 2-color viability assay based on membrane integrity and esterase activity (Figure 1). Plasma membrane integrity is determined by ethidium homodimer-1 which enters cells with compromised plasma membranes to bind DNA and emit a red fluorescence; live cells are identified by Calcein AM, a fluorogenic cell-permeant dye that is converted to a green fluorescence after interaction with intracellular esterases.

LIVE/DEAD Viability/Cytotoxicity Kit evaluates plasma membrane integrity and esterase activity

LIVE/DEAD Cell Viability Assay Kit evaluates plasma membrane integrity and metabolic activity

LIVE/DEAD Cell Viability Assay Kit, C12 Resazurin/SYTOX Green is a simple, 2-color viability assay to identify metabolically active cells from dead and damaged cells (Figure 2). In metabolically active cells, C12-resazurin is reduced to C12-resorufin to emit a red fluorescence. C12-resazurin is the lipophilic version of resazurin that is more permeable to live cells and the C12-resorufin product is better retained in cells. The SYTOX Green dye enters the compromised plasma membrane of dead and dying cells, and binds DNA, resulting in a green fluorescence. Cells that have undergone damage, will display a reduced red and green fluorescence.

Distinct green-fluorescent dead cells, red-fluorescent live cells, and double stained injured cells

Figure 2. LIVE/DEAD Cell Vitality Kit. Jurkat cells (T-cell leukemia, human) were induced with 10 μM camptothecin for 4 hours at 37°C, 5% CO2. The cells were incubated with the reagents in the LIVE/DEAD Cell Vitality Assay Kit and analyzed by flow cytometry. The dot plot of SYTOX Green fluorescence vs. resorufin fluorescence shows resolution of live, injured, and dead cell populations.

LIVE/DEAD kits for bacterial viability are convenient and easy-to-use 2-color fluorescent assays to discriminate between live and dead bacterial cell populations based on membrane integrity.

Learn more about these LIVE/DEAD bacterial viability kits.

 Platform*Fluorescent dyesEx/Em (nm) **Fluorescent ColorCat. No.
LIVE/DEAD BacLight Bacterial Viability KitFC, FM, MSYTO 9
propidium iodide
480/500
490/635
Green (Live)
Red (Dead)
L7007
LIVE/DEAD BacLight Bacterial Viability Kit, for microscopy & quantitative assaysFC, FM, MSYTO 9
propidium iodide
480/500
490/635
Green (Live)
Red (Dead)
L7012
LIVE/DEAD BacLight Bacterial Viability KitFC, FM, MSYTO 9
propidium iodide
480/500
490/635
Green (Live)
Red (Dead)
L13152
LIVE/DEAD BacLight Bacterial Viability and Counting KitFCSYTO 9
propidium iodide
485/498
535/617
Green (Live)
Red (Dead)
L34856
FilmTracer LIVE/DEAD Biofilm Viability KitFMSYTO 9
propidium iodide
482/500
490/635
Green (Live)
Red (Dead)
L10316
*FC = flow cytometry; FM = fluorescence microscopy; M = microplate assay
**Ex=excitation; Em=emission

LIVE/DEAD kits for bacterial viability

LIVE/DEAD kits for bacterial viability are convenient and easy-to-use 2-color fluorescent assays to discriminate between live and dead bacterial cell populations based on membrane integrity. These kits contain SYTO 9 green-fluorescent stain and PI red-fluorescent stain that differ in their ability to enter bacteria. When used alone, SYTO 9 will stain all bacteria in a population regardless of membrane integrity; however, PI will only enter bacteria with a compromised membrane causing reduced SYTO 9 fluorescence. With an optimized mixture, dead bacteria will fluoresce red, while live bacteria will fluoresce green. These assays have been optimized for use on fluorescence microscopy (Figure 3), flow cytometry (Figure 4), and microplate readers.

Learn more: bacterial viability assays for flow cytometry

Green-fluorescent live bacteria and red-fluorescent dead bacteria

Figure 3. LIVE/DEAD BacLight Bacterial Viability Kit.Micrococcus luteus and Bacillus cereus stained with the LIVE/DEAD BacLight Bacterial Viability Kit. When incubated with the SYTO 9 stain and the propidium iodide nucleic acid stain provided in this kit, live bacteria with intact cell membranes fluoresce green and dead bacteria with compromised membranes fluoresce red.

Figure 4. Analysis of bacterial cultures using the LIVE/DEAD BacLight Bacterial Viability and Counting Kit. Suspensions of live (untreated) and dead (alcohol-treated) Staphylococcus aureus (Panels A and C) and Escherichia coli (Panels B and D) were stained and analyzed by flow cytometry according to the LIVE/DEAD BacLight Bacterial Viability and Counting Kit protocol. Using green or red fluorescence versus side scatter cytogram (Panels A and B), the bacterial populations and the bead populations were gated (left and right boxes, respectively). Events in the bacteria region of each cytogram are also displayed in red fluorescence versus green fluorescence cytograms (Panels C and D). Live and dead bacteria/mL can be calculated from either the fluorescence versus side scatter cytogram or the green fluorescence versus red fluorescence cytogram, depending on which one shows the best separation of the live and dead populations. The position of the live and dead populations in these cytograms may be dependent on cell type and gram character. Some samples may exhibit events that fall outside the defined regions and should be evaluated appropriately (e.g., see Panel D).

LIVE/DEAD kits for fungi and yeast viability offer 2-color discrimination of live and dead fungal populations based on membrane integrity or metabolic activity and fungal cell wall labeling.

Learn more about these LIVE/DEAD fungi and yeast viability kits.

 Platform*Fluorescent dyesEx/Em (nm) **Fluorescent ColorCat. No.
LIVE/DEAD Yeast Viability KitFM, MFUN 1
Calcofluor White M2R
488/530
488/560-610
365/440
Green (All)
Red-orange (Live)
Blue (All)
L7009
LIVE/DEAD FungaLight Yeast Viability KitFCSYTO9 dye
propidium iodide
485/530
485/630
Green (Live)
Red (Dead)
L34952
*FC = flow cytometry; FM = fluorescence microscopy; M = microplate assay
**Ex=excitation; Em=emission

LIVE/DEAD Kits for fungi and yeast viability

LIVE/DEAD Yeast Viability Kits provide easy, reliable, and quantitative discrimination in pure or mixed cultures. Each kit offers 2-color discrimination based on membrane integrity or metabolic activity, and fungal cell wall labeling.

Learn more: yeast viability assays for flow cytometry

LIVE/DEAD Yeast Viability Kit evaluates metabolic activity

The Yeast Viability Kit (Figure 5) contains FUN 1 dye, that uses the plasma membrane integrity and metabolic activity of live populations to convert the yellow-green-fluorescent intracellular staining to red-orange intravacuolar structures, and Calcofluor White M2R which labels cell-wall chitin with a blue-fluorescence.

Yeast with yellow/green intracellular staining, red/orange intravacuolar structures, and blue cell wall chitin

Figure 5. LIVE/DEAD Yeast Viability Kit.Saccharomyces cerevisiae stained with the FUN 1 cell stain, which generates red-fluorescent intravacuolar structures, and with Calcofluor White M2R, a blue-fluorescent cell wall stain, both components of the LIVE/DEAD Yeast Viability Kit.

LIVE/DEAD FungaLight Yeast Viability Kit, for flow cytometry evaluates membrane integrity

The LIVE/DEAD FungaLight Yeast Viability Kit uses 2 nucleic acids stains - SYTO9 green-fluorescent stain and PI red-fluorescent stain (Figure 6). When used alone, SYTO 9 will stain all yeast in the population; while PI only enters yeast with a damaged membrane resulting in reduced SYTO 9 fluorescence. As a result, live yeast with uncompromised membrane will fluoresce green whereas dead yeast with compromised membrane will fluoresce red.

Forward and side scatter of the yeast population; and scatter plot with distinct green live and red dead yeast

Figure 6. Saccharomyces spp. cell suspensions stained with SYTO 9 dye and propidium iodide and analyzed using a BD FACSCalibur flow cytometry system (Becton Dickinson and Co.). Panel A shows the dot plot of forward scatter vs. side scatter of an untreated Saccharomyces culture, washed and stained with SYTO 9 dye and propidium iodide as described in the LIVE/DEAD FungaLight Yeast Viability Kit protocol. The region R1 contains particles of the appropriate size for yeast cells; the forward scatter trigger is set to exclude debris in the sample. Panel B shows the R1-gated staining pattern obtained following analysis of a sample of yeast containing a mixture of both live and heat-killed cells.

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