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DAPI is a popular blue fluorescent DNA dye. The dye binds to the minor groove of dsDNA with approximately 20-fold fluorescence enhancement.

Product Attributes

CAS number


Cellular localization


For live or fixed cells

For fixed cells, For live/intact cells

Assay type/options

DNA content/cell cycle (flow cytometry), Long term staining (24-72h), No-wash staining, Real-time imaging

Cell permeability

Membrane permeant

Apoptosis/viability marker

All cell stain




358/461 nm (with DNA)

Catalog #
10 mg
10 mg (Dilactate)
1 mL (10 mg/mL)
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Product Description

DAPI Products

ProductCatalog NumberMWUnit SizeFormat
DAPI (dihydrochloride)40011350.2510 mgYellow solid
DAPI (dilactate)40009457.4910 mgYellow solid
DAPI (10 mg/mL in water)40043457.491 mLYellow solution

DAPI (4′,6-Diamidino-2-Phenylindole, dihydrochloride) is a popular blue DNA dye that is used as a nuclear counterstain in fluorescence microscopy, chromosome staining and flow cytometry. The dye binds to the minor groove of dsDNA with approximately 20-fold fluorescence enhancement, with higher affinity for A-T rich regions.

We offer DAPI as a dihydrochloride powder (catalog no. 40011) or as a 10 mg/mL solution in water (catalog no. 40043). Alternatively, we also offer DAPI as a dilactate powder (catalog no. 40009) which is more water soluble than the dihydrochloride salt, and therefore a better choice for preparing stock solutions in water.

DAPI can be used to stain live bacteria (gram-positive and gram-negative) but in live yeast the staining is weak and not nuclear. See our Cellular Stains Table for more information on how our dyes stain various organisms.

Product Features:

  • Classic blue nuclear counterstain for fixed cells
  • Can be used at higher concentrations to stain live cells
  • λExEm (with DNA) = 358/461 nm
  • Store at 4°C and protect from light, especially in solution

Learn more about DAPI and our novel nuclear stains. We also offer antifade mounting media containing DAPI, in both hardset and wetset formulations.

Having trouble with your experiments? See our section on troubleshooting tips for fluorescent staining.


1. Biotechnic Histochem 70, 220 (1995).


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