Thermo Scientific Pierce DAPI Nuclear Counterstain is a fluorescent stain for DNA content and nuclei in fixed cells used in cell imaging techniques. A highly pure form of diamidino-2-phenylindole dye.

DAPI (diamidino-2-phenylindole) is a blue fluorescent probe that fluoresces brightly when selectively bound to the minor groove of double-stranded DNA, with higher fluorescence than unbound The fluorescence is about 20 times higher. Its DNA selectivity and high cell permeability enable efficient staining of cell nuclei with minimal background from the cytoplasm. DAPI is the classic nuclear counterstain used in immunofluorescence microscopy and is an important component of high-content screening methods that require cellular quantification of DNA content.

Features of DAPI nuclear counterstain:

•DAPI dye—diamidino-2-phenylindole is a DNA-specific blue fluorescent Stain
• Convenience—Choose from powder or easy-to-use DAPI dye solution (1 mg/mL)
• Cell Imaging—Cell-permeable dye available Efficiently stain fixed cells and quantify DNA content
• Counterstain—ideal for parallel detection of specific targets with fluorescence microscopy or high content screening (HCS) fluorescent antibodies

Characteristics of DAPI fluorescent dye:

•Other names:DAPI stain, DAPI dye, DNA content counterstain
•Chemical name: b>4,6'--diamidino-2-phenylindole dihydrochloride; 4',6-diamidino-2-phenylindole; 2-(4-amimidophenyl)-6 -Indoleguanidine dihydrochloride
• Molecular formula: C₁₆H₁₅N₅·2HCl
• Molecular weight:350.25
• Excitation wavelength:341±3 nm (nearly 360 nm when combined with dsDNA)
• Emission wavelength :452±3 nm (456 to 460 nm when bound to dsDNA)
• Extinction coefficient:at 347 nm> 30,600/M cm, soluble in methanol
• CAS Number:28718-90-3
• Purity: by HPLC, >95% at 240 nm (most lots >98% )
• Solubility:>1 mg/mL in water; the compound is soluble in DMF, water and various non-phosphate aqueous buffers
• Reactive groups: None; binds to the minor groove of double-stranded DNA

As a counterstain for fluorescence imaging methods, DAPI is compatiblefluorescein and rhodamine dye-labeled antibodies and other probes needle and Thermo Scientific DyLight Fluor. DAPI is more photostable than Hoechst dyes, but Hoechst 33342 can be used for live cell imaging, while DAPI is only suitable for fixed cells. DAPI is available as powdered solids and aqueous solutions.

Applications of DAPI stains:

• Detection of DNA in solution (Reference 4)
• Diagnosis of mycoplasma infections in cell cultures (Reference 5)
• In flow cytometry Measuring nuclear content and classifying chromosomes in cell analysis (Ref. 6)
• Assessing apoptosis (Ref. 7)
• Detecting nuclear and organoid DNA in immunofluorescence and in situ hybridization procedures (Ref. 2, 8 )
•Replacement of ethidium bromide for DNA staining in agarose gels (References 5, 9)
•Counterstaining of nuclei in histochemical methods using red fluorescent antibodies to detect specific targets ( Reference 8)
• Reports also indicate that DAPI binds to polyphosphates and other polyanions (Reference 10), dextran sulfate (Reference 11), and SDS (Reference 12).

Related products
DAPI solution (1 mg/mL)