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4′,6-Diamidine-2′-phenylindole dihydrochloride

Synonym: 2-(4-Amidinophenyl)-6-indolecarbamidine dihydrochloride, 4′,6-Diamidino-2-phenylindole dihydrochloride, DAPI dihydrochloride

  • CAS Number 28718-90-3

  • Empirical Formula (Hill Notation) C16H15N5 · 2HCl

  • Molecular Weight 350.25

  •  Beilstein Registry Number 4894417

  •  MDL number MFCD00012681

  •  PubChem Substance ID 329748990



assay   >90%
form   powder
packaging   pkg of 10 mg
mfr. no.   Roche
storage condition   protect from light
absorption   Amax 340 nm in aq. suspension
fluorescence   λex 340 nm; λem 488 nm (nur DAPI)
  λex 364 nm; λem 454 nm (DAPI-DNA-Komplex)
shipped in   ambient


Biochem/physiol Actions

Cell permeable fluorescent minor groove-binding probe for DNA. Binds to the minor groove of double-stranded DNA (preferentially to AT rich DNA), forming a stable complex which fluoresces approximately 20 times greater than DAPI alone.

Other Notes

For life science research only. Not for use in diagnostic procedures.


The fluorescent dye DAPI binds selectively to DNA and forms strongly fluorescent DNA-DAPI complexes with high specificity. DAPI, once added to tissue culture cells, is rapidly taken up into cellular DNA, yielding highly fluorescent nuclei and no detectable cytoplasmic fluorescence. When the cells are contaminated with Mycoplasmas, characteristic discrete fluorescent foci are readily detected over the cytoplasm and sometimes in intercellular spaces.

Preparation Note

Working solution: Solubility: 25 mg/ml in water

Preparation of stock solution

Dissolve in double-dist. water to a final concentration of 1 to 5 mg/ml.
Note: Do not use any buffers.

Preparation of working solution

Dilute the stock solution with methanol to a final concentration of 1 μg/ml. The working solution is stable at 2 to 8 °C for about 6 months.
Storage conditions (working solution): Stock solution (1 to 5 mg/ml) at -15 to -25 °C for 12 months.
Working solution (1μg/ml) at 2 to 8 °C for about 6 months.


Purity: >90% (from N)


In 2 to 10 ml double-dist. water; 1 to 5 mg/ml final concentration.
Note: Prepare aliquots and store at -15 to -25 °C.


DAPI is a fluorescent dye that binds selectively to double-stranded DNA and forms strongly fluorescent DNA-DAPI complexes with high specificity. It is commonly used to detect mycoplasma in cell culture via fluorescence microscopy.

DAPI is several times more sensitive than ethidium bromide for staining DNA in agarose gels. It may be used for photofootprinting of DNA, to detect annealed probes in blotting applications by specifically visualizing the double-stranded complex, and to study the changes in DNA and analyze DNA content during apoptosis using flow cytometry. DAPI staining has also been shown to be a sensitive and specific detection method for mycoplasma.

Safety & Documentation

Safety Information

NONH for all modes of transport

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