alamarblue microplate assay showing the color change from blue to pink across the plate

Microplate assays provide information on entire cell populations rather than tracking the behavior of individual cells. We offer microplate assays for whole cells and assays performed on disrupted cells or cell lysates. Metabolic activity is commonly used as a viability indicator, but for some applications it can be important to assess viability independent of metabolic state, and appropriate assays are listed below. In some cases, cells are required for additional downstream functional analysis, and alamarBlue HS is an excellent nontoxic indicator of viability.

Microplate assays for cell viability selection guide

  alamarBlue Cell Viability Reagent alamarBlue HS Cell Viability Reagent PrestoBlue Cell Viability Reagent PrestoBlue HS Cell Viability Reagent
Use Recommended in cases of extended viability studies or when using a high cell density in microplate assays Recommended for quick viability determination in microplate assays (10 minute incubation)
Measurement Metabolic activity of mammalian cells, bacteria, plant and fungi Metabolic activity of mammalian cells
Mechanism of detection Resazurin is converted to fluorescent resorufin
Assay Sensitivity?
Cat. no. DAL1025 A50100 A13261 P50200
  Learn more about differences in alamarBlue and alamarBlue HS Learn more about differences in PrestoBlue and PrestoBlue HS
  CyQUANT MTT Cell Viability Assay CyQUANT XTT Cell Viability Assay
Use Colorimetric assay for the detection of cell viability as a function of cellular redox potential
Measurement Redox potential in active mammalian cells
Mechanism of detection Water-soluble MTT is converted into an insoluble purple formazan product Water-soluble XTT is converted into a water-soluble orange formazan product
Kit components
  • MTT reagent (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide)
  • Sodium dodecyl sulfate (SDS)
  • XTT Reagent is used to assess cell viability as a function of cellular redox potential
  • An electron coupling reagent to improve the dynamic range of the assay
Absorbance 570 nm 450 nm
Cat. no. V13154 X12223
  LIVE/DEAD Viability/Cytotoxicity Kit, for mammalian cells HCS LIVE/DEAD Green Kit
Measurement
  • Two-color assay
  • Influx of cell-impermeant dye in cells that have lost plasma membrane integrity
  • Esterase activity
  • Two-color assay
  • Influx of cell-impermeant dye in cells that have lost plasma membrane integrity
  • Total cell demarcation
Cell-impermeant dye (Ex/Em, nm)
  • Calcium AM (488 nm/535 nm)
  • Ethidium homodimer-1 (528 nm/617 nm)
  • Image-iT DEAD Green (488 nm/515 nm)
  • NuclearMask Deep Red* (636 nm/686 nm)
  • Hoechst 33342* (350 nm/461 nm)

*For total cell demarcation choose from one of these. Both are provided in the kit.
Sample type Adherent or suspended cells Adherent cells
Cat. no. L3224 H10290
  CyQUANT Cytotoxicity Assay Kit (G6PD Release Assay) CyQuant LDH Cytotoxicity Assay- Fluorescence CyQuant LDH Cytotoxicity Assay
Assay Type Fluorescent Colorimetric
Measurement Detection of glucose-6-phosphate (G6P) release from damaged cells by an enzymatic process that leads to the reduction of resazurin into red-fluorescent resorufin Detection of extracellular lactate dehydrogenase (LDH) from damaged cells by an enzymatic process that leads to the reduction of resazurin into red-fluorescent resorufin Detection of extracellular LDH from damaged cells by an enzymatic process that leads to the formation of a red formazan product
Efflux detection reagent Resorufin (Ex/Em: 560 nm/590 nm) Resorufin (Ex/Em: 560 nm/590 nm) Formazan (Em: 490 nm)
Sample type >Cell suspension and surrounding media
Cat. no. V23111 C20302 C20300
  LIVE/DEAD BacLight Bacterial Viability Kit, for microscopy and quantitative assays LIVE/DEAD Yeast Viability Kit
Assay type Bacterial cell viability Yeast cell viability
Measurement Influx of cell-impermeant dye in cells that have lost plasma membrane integrity
Readout
  • Two-color assay
  • Membrane-permeant DNA dye stains intact, live cells green
  • Membrane-impermeant DNA dyes stains dead cells red
  • Live cell determination can also be combined with fluorescent Gram staining
  • Two-color assay
  • A membrane stain detects both live and dead cells with a blue signal
  • In viable cells, the vacuole stains orange/red
Detection Reagent (Ex/Em, nm)
  • Propidium iodide (485 nm/530 nm)
  • SYTO 9 (630 nm)
  • FUN 1 (485 nm/530 nm)
  • Calcofluor White (620 nm)
Sample Type Bacterial suspension Pure or mixed cultures, body fluids, or environmental samples
Cat. no. L7012 L7009
  alamarBlue Cell Viability Reagent alamarBlue HS Cell Viability Reagent PrestoBlue Cell Viability Reagent PrestoBlue HS Cell Viability Reagent
Use Recommended in cases of extended viability studies or when using a high cell density in microplate assays Recommended for quick viability determination in microplate assays (10 minute incubation)
Measurement Metabolic activity of mammalian cells, bacteria, plant and fungi Metabolic activity of mammalian cells
Mechanism of detection Resazurin is converted to fluorescent resorufin
Assay Sensitivity?
Cat. no. DAL1025 A50100 A13261 P50200
  Learn more about differences in alamarBlue and alamarBlue HS Learn more about differences in PrestoBlue and PrestoBlue HS
  CyQUANT MTT Cell Viability Assay CyQUANT XTT Cell Viability Assay
Use Colorimetric assay for the detection of cell viability as a function of cellular redox potential
Measurement Redox potential in active mammalian cells
Mechanism of detection Water-soluble MTT is converted into an insoluble purple formazan product Water-soluble XTT is converted into a water-soluble orange formazan product
Kit components
  • MTT reagent (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide)
  • Sodium dodecyl sulfate (SDS)
  • XTT Reagent is used to assess cell viability as a function of cellular redox potential
  • An electron coupling reagent to improve the dynamic range of the assay
Absorbance 570 nm 450 nm
Cat. no. V13154 X12223
  LIVE/DEAD Viability/Cytotoxicity Kit, for mammalian cells HCS LIVE/DEAD Green Kit
Measurement
  • Two-color assay
  • Influx of cell-impermeant dye in cells that have lost plasma membrane integrity
  • Esterase activity
  • Two-color assay
  • Influx of cell-impermeant dye in cells that have lost plasma membrane integrity
  • Total cell demarcation
Cell-impermeant dye (Ex/Em, nm)
  • Calcium AM (488 nm/535 nm)
  • Ethidium homodimer-1 (528 nm/617 nm)
  • Image-iT DEAD Green (488 nm/515 nm)
  • NuclearMask Deep Red* (636 nm/686 nm)
  • Hoechst 33342* (350 nm/461 nm)

*For total cell demarcation choose from one of these. Both are provided in the kit.
Sample type Adherent or suspended cells Adherent cells
Cat. no. L3224 H10290
  CyQUANT Cytotoxicity Assay Kit (G6PD Release Assay) CyQuant LDH Cytotoxicity Assay- Fluorescence CyQuant LDH Cytotoxicity Assay
Assay Type Fluorescent Colorimetric
Measurement Detection of glucose-6-phosphate (G6P) release from damaged cells by an enzymatic process that leads to the reduction of resazurin into red-fluorescent resorufin Detection of extracellular lactate dehydrogenase (LDH) from damaged cells by an enzymatic process that leads to the reduction of resazurin into red-fluorescent resorufin Detection of extracellular LDH from damaged cells by an enzymatic process that leads to the formation of a red formazan product
Efflux detection reagent Resorufin (Ex/Em: 560 nm/590 nm) Resorufin (Ex/Em: 560 nm/590 nm) Formazan (Em: 490 nm)
Sample type >Cell suspension and surrounding media
Cat. no. V23111 C20302 C20300
  LIVE/DEAD BacLight Bacterial Viability Kit, for microscopy and quantitative assays LIVE/DEAD Yeast Viability Kit
Assay type Bacterial cell viability Yeast cell viability
Measurement Influx of cell-impermeant dye in cells that have lost plasma membrane integrity
Readout
  • Two-color assay
  • Membrane-permeant DNA dye stains intact, live cells green
  • Membrane-impermeant DNA dyes stains dead cells red
  • Live cell determination can also be combined with fluorescent Gram staining
  • Two-color assay
  • A membrane stain detects both live and dead cells with a blue signal
  • In viable cells, the vacuole stains orange/red
Detection Reagent (Ex/Em, nm)
  • Propidium iodide (485 nm/530 nm)
  • SYTO 9 (630 nm)
  • FUN 1 (485 nm/530 nm)
  • Calcofluor White (620 nm)
Sample Type Bacterial suspension Pure or mixed cultures, body fluids, or environmental samples
Cat. no. L7012 L7009

Ready-to-use fluorescent cell health indicators for microplate assays

For HTS applications, a viability assay is ideally performed in an add-and-read format, requiring only three steps—addition of reagent, incubation, and measurement of output—with no mixing, washing, or cell lysis required. Add-and-read resazurin-based assays are commonly used to quantify metabolic activity of cells.

In addition to ease of use, resazurin-based assays provide extended linear ranges, ample signal windows, and the flexibility to measure in either endpoint or kinetic mode and with either fluorescence- or absorption-based instrumentation. The endpoint mode is often used in primary screenings, in which the goal is to perform fast screening campaigns to identify hit compounds from large chemical collections. The kinetic mode is more applicable to secondary screenings, in which the time-dependent cytotoxic effects of selected hits are assessed for mechanistic purposes.

alamarBlue and PrestoBlue Cell Viability Reagents are ready-to-use resazurin-based solution that function as a cell health indicator by using the reducing power of living cells to quantitatively measure viability. Upon entering living cells, resazurin is reduced to resorufin, a compound that is red in color and highly fluorescent. We have introduced two new, superior versions of these products—the Invitrogen PrestoBlue HS (High Sensitivity) and alamarBlue HS (High Sensitivity) Cell Viability Reagents—which contain highly purified resazurin that provides a >50% reduction in background signal and >100% signal-to-background ratio increase compared to the standard alamarBlue and PrestoBlue reagents.

PrestoBlue HS reagent is recommended for quick viability determination, whereas alamarBlue HS reagent is recommended in cases of extended viability studies or when using a high cell density.

Learn more about alamarBlue and alamarBlue HS
Learn more about PrestoBlue and PrestoBlue HS

Colorimetric viability microplate assays

The CyQUANT MTT Cell Viability Assay utilizes the well-established and widely used MTT reagent to determine mammalian cell viability. The redox potential in active mammalian cells reduces MTT to a strongly pigmented formazan product. After solubilization, the absorbance of the formazan can be measured with a microplate absorbance reader (570 nm emission).

Learn more about the CyQUANT MTT Cell Viability Assay

The CyQUANT XTT Cell Viability Assay is a complete, optimized assay that generates a consistent colorimetric detection of viable mammalian cells. The assay kit consists of two reagents, XTT Reagent (with emission at 450 nm) and Electron Coupling Reagent. XTT Reagent is used to assess cell viability as a function of cellular redox potential, and the electron coupling reagent improves the dynamic range of the assay.

Learn more about the CyQuant XTT Cell Viability Assay

Plasma membrane integrity microplate assays for cytotoxicity

The loss of plasma membrane integrity is a key marker of cell death. Assays have been developed to detect esterase activity in damaged cells, release of cytosolic enzymes such as lactate dehydrogenase (LDH) or glucose 6-phosphate dehydrogenase (G6PD) or from damaged cells, or the ability of a non-fluorescent, cell-impermeant dye to fluorescence upon binding to DNA in damaged cells.

See selection guide for reagents that measure influx of cell-impermeant dyes
See selection guide for reagents that measure efflux or release of cytosolic enzymes (LDH or G6PD) into media

Microplate assays for microorganism cell viability

Assays that detect membrane integrity of bacterial and yeast cell viability are available.

See selection guide for bacterial and yeast cell viability

Bacterial cell viability
A combination of membrane-permeant and -impermeant DNA dyes can be used to stain intact cells green and dead cells red. For bacteria, live cell determination can also be combined with fluorescent Gram staining.

Yeast cell viability
A membrane stain is used to detect both live and dead cells with a blue signal. In viable cells, the vacuole stains orange/red, providing a two-color assay.

Expertly detect fluorescence with Thermo Scientific plate readers

Thermo Scientific plate readers

High-sensitivity fluorescence detection for 96-1,536 samples can be quickly performed on Fluoroskan or Fluoroskan FL Microplate Fluorometer or Varioskan LUX Multimode Microplate Reader using Invitrogen reagents for optimal detection. Take advantage of automatic dynamic range selection to get optimal gain settings for each individual well and automation capabilities for even higher throughput.

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