DAPI, dihydrochloride

• Cat.No.: DAPI-019

Specification

• Description: 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. DAPI can be used to stain mammalian cells as well as gram-positive and gram-negative bacteria. In yeast, the staining is weak and not nuclear. DAPI is less membrane permeant than Hoechst, and is typically used to stain fixed cells. On the other hand, Hoechst dyes are membrane-permeant and more often used for live or fixed cell staining and cell cycle analysis. While Hoechst and DAPI show less cytotoxicity than intercalating DNA dyes, they bind DNA in living cells and are potentially hazardous. DAPI and Hoechst undergo photoconversion by UV excitation to form green fluorescent dyes, which can lead to artifacts in multi-color imaging.
• Form: Yellow solid
• Molecular Mass: 350
• Molecular Information: C16H17Cl2N5
• CAS number: 28718-90-3
• Solubility: Soluble in water
• Absorption/Emission: 358/461 nm (with DNA)
• General Staining Protocol: Staining of fixed cells or tissue sections
  1. Dilute DAPI to 1 μg/mL in PBS. DAPI can be included together with antibodies or other probes, and can be diluted in buffers with detergent or blocking agents if convenient.
  2. Add the staining solution to cells or tissue sections and incubate at room temperature for at least 5 minutes.
  3. Image the samples with UV (355 nm) excitation in the DAPI channel.
  Notes:
  a. Samples can be stored at 4 centigrade after staining and before imaging.
  b. DAPI can be included directly in antifade mounting medium for one-step mounting and staining. When using DAPI in mounting medium, longer incubation times may be required for DAPI to completely penetrate the cell nuclei.
• Probe cellular localization: Nucleus
• For live or fixed cells: For fixed cells
• Detection method/readout: Fluorescence microscopy, Flow cytometry
• Assay type/options: DNA content/cell cycle profiling by flow cytometry, Tissue staining
• Cell permeability: Membrane permeant
• Apoptosis/viability marker: All cell stain
• Colors: Blue
• Staining bacteria or yeast: In bacteria, DAPI staining is dim compared to what is observed in mammalian cells. Live or killed bacteria can be stained with 10 μg/mL DAPI in PBS or 150 mM NaCl for 30 minutes at room temperature. DAPI tends to stain dead cells more brightly than live cells.
  In S. cerevisiae, DAPI preferentially stains dead yeast with nuclear and cytoplasmic staining when used at 10 μg/mL in PBS; in live yeast DAPI shows dim mitochondrial staining.
• Stability: Product is stable for at least one year from date of receipt when stored as recommended.
• Storage: Store DAPI (solid form) desiccated at 4 centigrade, protected from light. Store DAPI in H2O at 4 centigrade, protected from light.
• Reference: 1. Biochemistry 31, 3103 (1992);
  2. Biochem Biophys Res Commun 170, 270 (1990);
  3. J. Histochem Cytochem 38, 1323 (1990)