AAT Bioquest

SunRed™ Acetate

Fluorescence images of HeLa cells stained with SunRed™ Acetate in a Costar black wall/clear bottom 96-well plate.
Fluorescence images of HeLa cells stained with SunRed™ Acetate in a Costar black wall/clear bottom 96-well plate.
Fluorescence images of HeLa cells stained with SunRed™ Acetate in a Costar black wall/clear bottom 96-well plate.
Ordering information
Catalog Number
Unit Size
Add to cart
Additional ordering information
InternationalSee distributors
ShippingStandard overnight for United States, inquire for international
Physical properties
Molecular weight~350
Spectral properties
Excitation (nm)653
Emission (nm)661
Storage, safety and handling
H-phraseH303, H313, H333
Hazard symbolXN
Intended useResearch Use Only (RUO)
R-phraseR20, R21, R22
StorageFreeze (< -15 °C); Minimize light exposure


Molecular weight
Excitation (nm)
Emission (nm)
Esterase-catalyzed hydrolysis of Sun Red acetate (SRA) yields the Sun Red fluorophore that can be excited with the 633 nm laser with emission of ~660 nm. The fluorescence of Sun Red can be readily detected using the Cy5 filter set that is commonly equipped with most of the commercial fluorescence instruments. Although Sun Red is readily excited at 633 nm with red emission of ~660 nm, SRA has very minimal absorption at 633 nm without red emission, making SRA one of the most sensitive NIR esterase substrates. SRA provides a second color for cell viability assay while the popular fluorescein color can used for another cellular functional assay. SRA is a non-fluorescent hydrophobic compound that can pass through the cell membrane whereupon intracellular esterases hydrolyze the acetate group producing the highly fluorescent product Sun Red. The Sun Red molecule accumulates in cells that possess intact membranes so the deep red fluorescence can be used as a marker of cell viability. Cells that do not possess an intact cell membrane or an active metabolism may not accumulate the fluorescent product and therefore do not exhibit deep red fluorescence. SRA may be used in combination with a green vital stain such as a FITC or Alexa Fluor 488-labeled antibody.


Fluorescence microscope

Excitation620 nm
Emission660 nm
Recommended plateBlack wall/clear bottom
Instrument specification(s)Cy5 filterset

Fluorescence microplate reader

Excitation620 nm
Emission660 nm
Cutoff640 nm
Recommended plateSolid black

Example protocol


Protocol summary

  1. Prepare cells with test compounds
  2. Remove the medium
  3. Add SunRed™ Acetate working solution (100 µL/well/96-well plate or 25 µL/well/384-well plate)
  4. Incubate at 37°C, 5% CO2 incubator for 1 hour
  5. Wash and replace the working solution with HHBS
  6. Read fluorescence intensity at Ex/Em = 620/660 nm (cut off 640 nm)

Important notes
The following is the recommended protocol. It only provides a guideline, should be modified according to the specific needs.


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. SunRed™ acetate stock solution (2 to 10 mM)
Prepare a 2 to 10 mM stock solution of SunRed™ acetate in DMSO. The stock solution should be used promptly.



SunRed™ acetate working solution:
Prepare SunRed™ acetate working solution at 5 to 10 µM in 1X Hank’s salt solution with 20 mM Hepes buffer (HHBS) or buffer of your choice before the experiment.

For guidelines on cell sample preparation, please visit


  1. Remove the medium from the cells.

  2. Add 100 µL/well (96-well plate) or 25 µL/well (384-well plate) of SunRed™ acetate working solution.

  3. Incubate the SunRed™ acetate working solution plate at room temperature or 37°C for 1 hour, protected from light. The appropriate incubation time depends on the individual cell type and cell concentration used. Optimize the incubation time for each experiment. 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 = 620/660 nm (cut off 640 nm).


Open in Advanced Spectrum Viewer

Spectral properties

Excitation (nm)653
Emission (nm)661

Product Family

NameExcitation (nm)Emission (nm)Correction Factor (280 nm)
SunRed™ SE5926090.366
SunRed™ Phosphate653661-



View all 18 references: Citation Explorer
The secreted esterase of group a streptococcus is important for invasive skin infection and dissemination in mice
Authors: Zhu H, Liu M, Sumby P, Lei B.
Journal: Infect Immun (2009): 5225
Neuropathy target esterase is required for adult vertebrate axon maintenance
Authors: Read DJ, Li Y, Chao MV, Cavanagh JB, Glynn P.
Journal: J Neurosci (2009): 11594
Application of glutaraldehyde for the staining of esterase-active cells with carboxyfluorescein diacetate
Authors: Morono Y, Takano S, Miyanaga K, Tanji Y, Unno H, Hori K.
Journal: Biotechnol Lett (2004): 379
Evaluation of fitness components in strains of Drosophila mulleri carrying different genotypes for an esterase
Authors: Lourenco MF, Ceron CR, Carareto CM.
Journal: Cytobios (2001): 125
Purification and properties of an esterase from the yeast Saccharomyces cerevisiae and identification of the encoding gene
Authors: Degrassi G, Uotila L, Klima R, Venturi V.
Journal: Appl Environ Microbiol (1999): 3470
Determination of growth and lysis kinetics in plant cell suspension cultures from the measurement of esterase release
Authors: Steward N, Martin R, Engasser JM, Goergen JL.
Journal: Biotechnol Bioeng (1999): 114
Comparison of two in vitro activation systems for protoxicant organophosphorous esterase inhibitors
Authors: Barber D, Correll L, Ehrich M.
Journal: Toxicol Sci (1999): 16
Organophosphorus neuropathy target esterase inhibitors selectively block outgrowth of neurite-like and cell processes in cultured cells
Authors: Li W, Casida JE.
Journal: Toxicol Lett (1998): 139
Esterase-6 gene-enzyme system and resistance of Drosophila to increased temperature
Authors: Totskii VN, Eserkepova EV, Dzhan ZU.
Journal: Genetika (1994): 342
Causes and consequences of esterase 6 enzyme activity variation in pre-adult Drosophila melanogaster
Authors: Oakeshott JG, Saad M, Game AY, Healy MJ.
Journal: Heredity (1994): 160