TUNEL Assay Apoptosis Detection Kit

TUNEL Assay Apoptosis Detection Kit

TUNEL Assay Apoptosis Detection Kit

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The CF® dye TUNEL Assay Apoptosis Detection Kit label apoptotic cells in fixed tissue sections or cellular samples for fluorescence microscopy or flow cytometry.

Product Description

These kits use enzymatic labeling of DNA double-strand breaks to fluorescently stain apoptotic cells in fixed samples or tissue sections.


  • Direct labeling of DNA ds breaks with fluorescent dUTP
  • Bright & photostable next-generation CF® dyes
  • For fixed cells or tissue sections
  • Detect by fluorescence microscopy or flow cytometry

Kit Components

  • Equilibration Buffer
  • CF® Dye TUNEL Reaction Buffer
  • TdT Enzyme (calf thymus; recombinant, produced in E. coli)

Dye Options

  • Green fluorescent CF®488A (Ex/Em 490/515 nm)
  • Red fluorescent CF®594 (Ex/Em 593/614 nm)
  • Far-red fluorescent CF®640R (Ex/Em 642/662 nm)

Learn more about Biotium’s next-generation CF® Dyes.

In the TUNEL assay, TdT enzyme catalyzes the addition of labeled dUTP to the 3′- ends of the internucleosomal DNA strand breaks that are a hallmark of apoptosis. The CF® dye TUNEL Assay Apoptosis Detection Kits employs dUTP conjugated to the exceptionally bright and photostable fluorescent dyes, for single step fluorescent TUNEL labeling of fixed cells or tissues for analysis by fluorescence microscopy or flow cytometry.

See our full selection of Cell Viability & Apoptosis Kits.


Product Attributes

Apoptosis/viability marker DNA fragmentation
For live or fixed cells For fixed cells/tissue sections
Detection method/readout Fluorescence microscopy, Flow cytometry
Assay type/options Endpoint assay
Fixation options Permeabilize before staining, Fix before staining (methanol), Fix before staining (formaldehyde)
Colors Green, Red, Far-red
Product origin TdT enzyme (calf thymus); recombinant, produced in E. coli
Storage Conditions Store at -10 to -35 °C, Protect from light

Reference Publications

Masayasu Toyomoto, Asuka Inoue, et al.

S1PR3–G12-biased agonist ALESIA targets cancer metabolism and promotes glucose starvation

Cell Chemical Biology 28, 1132–1144

DOI: https://doi.org/10.1016/j.chembiol.2021.01.004

Article Snippet: “HeLa cells were stained using the CF640R TUNEL assay apoptosis detection kit (Biotium) and Hoechst 33342, according to the manufacturers’ instructions.”


Zhihao Jia, Yaohui Nie, et al.

A requirement of Polo-like kinase 1 in murine embryonic myogenesis and adult muscle regeneration

eLife 8:e47097.

DOI: https://doi.org/10.7554/eLife.47097

Article Snippet: “For TUNEL and Pax7 staining, slides were fixed in 4% PFA for 10 min and then subjected to the TUNEL reaction using the CF488A TUNEL Assay Apoptosis Detection Kit (Biotium) according to the manufacturer’s instructions.”


Laura S. Shankman, Samantha T. Fleury, et al.

Efferocytosis by Paneth cells within the intestine

Current Biology 31, 2469–2476

DOI: https://doi.org/10.1016/j.cub.2021.03.055

Article Snippet: “One set of enteroids underwent apoptosis detection using the CF640R TUNEL Assay (Biotium #30074) allowing the reagent to sit for 2 hours at 37°C before EDU detection (GeneCopoeia #A003) for 30min.”


Kubelt, C., Molkewehrum, H., Lucius, R. et al.

Influence of Simulated Deep Brain Stimulation on the Expression of Inflammatory Mediators by Human Central Nervous System Cells In Vitro

Neuromol Med 24, 169–182 (2022).

DOI: https://doi.org/10.1007/s12017-021-08674-y

Article Snippet:Apoptosis due to electrical stimulation was detected by TUNEL assays using CF® dye TUNEL Assay Apoptosis Detection Kit (Biotium, Inc., Fremont, CA) performed after 24 h of stimulation.”


Biyashev, D., Siwicka, Z.E., Onay, U.V. et al.

Topical application of synthetic melanin promotes tissue repair

npj Regen Med 8, 61 (2023)

DOI: https://doi.org/10.1038/s41536-023-00331-1

Article Snippet:The TUNEL assay was performed using the CF®640 R Dye TUNEL assay apoptosis detection kits (Biotium, 30074) according to the manufacturer’s directions and visualized with an ECLIPSE Ti2 inverted microscope (Nikon Tokyo, Japan) using a DS-Qi2 camera (Nikon).”


Martin Kronschläger, Manuel Ruiß, Thomas Dechat, Oliver Findl

Single high-dose peroral caffeine intake inhibits ultraviolet radiation-induced apoptosis in human lens epithelial cells in vitro

Acta Ophthalmol, 99: e587-e593.

DOI: https://doi.org/10.1111/aos.14641

Article Snippet:Afterwards, lens capsules were stained using a commercial TdT-mediated dUTP-biotin nick end labeling (TUNEL) assay kit (CF 594; TUNEL Assay Apoptosis Detection Kit; Biotium, Fremont, CA, USA).”


Masahiro Miyata, Eri Matsuki, Kazunobu Ichikawa, et al.

Allogeneic T cells cause acute renal injury after hematopoietic cell transplantation

Blood Adv (2023) 7 (22): 6936–6948.

DOI: https://doi.org/10.1182/bloodadvances.2023009721

Article Snippet:After removing the floating cells and medium, the wells were washed with phosphate-buffered saline, followed by terminal deoxynucleotidyl transferase–mediated deoxyuridine triphosphate nick end labeling (TUNEL) using the CF 594 TUNEL Assay Apoptosis Detection Kit (Biotium, Fremont, CA).”