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Cell Meter™ Cell Viability Assay Kit *Green Fluorescence*

CHO-K1 cell number response was measured with Cell Meter™ Cell Viability Assay Kit. CHO-K1 cells at 0 to 5,000 cells/well/100 µL were seeded overnight in a Costar black wall/clear bottom 96-well plate. The cells were incubated with 100 µL/well of dye-loading solution for 1 hour at 37°C. The fluorescence intensity was measured at Ex/Em = 490/ 525 nm with NOVOstar instrument (from BMG Labtech). The fluorescence intensity was linear (R square = 1) to the cell number as indicated.
CHO-K1 cell number response was measured with Cell Meter™ Cell Viability Assay Kit. CHO-K1 cells at 0 to 5,000 cells/well/100 µL were seeded overnight in a Costar black wall/clear bottom 96-well plate. The cells were incubated with 100 µL/well of dye-loading solution for 1 hour at 37°C. The fluorescence intensity was measured at Ex/Em = 490/ 525 nm with NOVOstar instrument (from BMG Labtech). The fluorescence intensity was linear (R square = 1) to the cell number as indicated.
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Catalog Number22786
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Additional ordering information
InternationalSee distributors
ShippingStandard overnight for United States, inquire for international
Spectral properties
Excitation (nm)494
Emission (nm)514
Storage, safety and handling
H-phraseH303, H313, H333
Hazard symbolXN
Intended useResearch Use Only (RUO)
R-phraseR20, R21, R22


Excitation (nm)
Emission (nm)
Our Cell Meter™ assay kits are a set of tools for monitoring cell viability. There are a variety of parameters that can be used for monitoring cell viability. This kit uses the non-fluorescent calcein AM that becomes strongly fluorescent upon entering into live cells. Calcein AM is a hydrophobic compound that easily permeates intact live cells. The hydrolysis of the non-fluorescent calcein AM by intracellular esterases generates the strongly fluorescent hydrophilic calcein that is well-retained in the cell cytoplasm. The esterase activity is proportional to the number of viable cells, and thus directly related to the fluorescence intensity of calcein generated from the esterase-catalyzed hydrolysis of calcein AM. Cells grown in black-walled plates can be stained and quantified in less than two hours. The assay is more robust than the tetrazolium salt or Alarmar Blue™-based assays. It can be readily adapted for high-throughput assays in a wide variety of fluorescence platforms such as microplate assays, immunocytochemistry and flow cytometry. It is useful for a variety of studies, including cell adhesion, chemotaxis, multidrug resistance, cell viability, apoptosis and cytotoxicity. The kit provides all the essential components with an optimized cell-labeling protocol. It is suitable for proliferating and non-proliferating cells, and can be used for both suspension and adherent cells. Using 100 uL of reagents per well in a 96-well format, this kit provides sufficient reagents to perform 500 assays. Using 25 uL of reagents per well in a 384-well format, this kit provides sufficient reagents to perform 2000 assays.


Fluorescence microplate reader

Excitation490 nm
Emission525 nm
Cutoff515 nm
Recommended plateBlack wall/clear bottom
Instrument specification(s)Bottom read mode


Component A: CytoCalcein™ Green5 vials, lyophilized
Component B: DMSO1 vial (200 µL)
Component C: Assay Buffer1 bottle (50 mL)

Example protocol


Protocol summary

  1. Prepare cells with test compounds
  2. Add the same volume of working solution as the cell medium
  3. Incubate at room temperature or 37°C for 1 hour 
  4. Monitor fluorescence with fluorescence microplate reader at Ex/Em= 490/525 nm (Cutoff=515 nm)

Important notes
Thaw one of each kit component at room temperature before use.


Unless otherwise noted, all unused stock solutions should be divided into single-use aliquots and stored at -20 °C after preparation. Avoid repeated freeze-thaw cycles.

1. CytoCalcein™ Green stock solution:
Add 20 µL of DMSO (Component B) into the vial of CytoCalcein™ Green (Component A) and mix well. Protect from light. Note: 20 µL of CytoCalcein™ Green stock solution is enough for one plate.


Add the whole content (20 µL) of CytoCalcein™ Green stock solution into 10 mL of Assay Buffer (Component C) and mix well. Note: The working solution is stable for at least 2 hours at room temperature. Note: If the cells, such as CHO cells, contain organic-anion transporters which cause the leakage of the fluorescent dye over time, a probenecid stock solution should be prepared and added to the loading buffer at a final in-well working concentration of 1 - 2.5 mM.


Cells Preparation:

Plate 100 to 100, 000 cells/well in a tissue culture microplate with black wall and clear bottom. Add test compounds into the cells and incubate for a desired period of time (such as 24, 48 or 96 hours) in a 37 °C, 5% CO2 incubator.

For blank wells (medium without the cells), add the same amount of compound buffer. The suggested total volume is 100 µL for a 96-well plate, and 25 µL for a 384-well plate. Note: Each cell line should be evaluated on an individual basis to determine the optimal cell density for proliferation or cytotoxicity induction. For proliferation assays, use fewer cells; for cytotoxicity assays, use more cells to start with.

Sample Protocol:

  1. Treat cells with test compounds as desired. Note: It is not necessary to wash cells before adding compound. However, if tested compounds are serum sensitive, growth medium and serum factors can be aspirated away before adding compounds. Add 100 µL/well (96-well plate) or 25 µL/well (384-well plate) of 1X Hank’s salt solution and 20 mM Hepes buffer (HHBS) or the buffer of your choice after aspiration. Alternatively, cells can be grown in serum-free media.

  2. Add 100 µL/well (96-well plate) or 25 µL/well (384-well plate) of dye-loading solution.

  3. Incubate the dye-loading plate at room temperature or 37°C for 1 hour, protected from light. (The incubation time could be from 15 minutes to overnight. We got the optimal results with the incubation time less than 4 hours.) Note: The appropriate incubation time depends on the individual cell type and cell concentration used. Optimize the incubation time for each experiment. Note: DO NOT wash the cells after loading. Note: For non-adherent cells, it is recommended to centrifuge cell plates at 800 rpm for 2 minutes with brake off after incubation.

  4. Monitor the fluorescence intensity at Ex/Em = 490/525 nm with cutof=515 nm.


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Spectral properties

Excitation (nm)494
Emission (nm)514


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Application notes

Annexin V