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Ethidium Homodimer I (EthD-I)

Ethidium Homodimer I is a dead cell specific fluorescent nucleic acid dye.

Product Attributes

CAS number


Cellular localization

Nucleus & cytoplasm

Cell permeability

Membrane impermeant

Apoptosis/viability marker

Dead cell stain




528/617 nm (with DNA)

Catalog #
1 mg
0.5 mL (2 mM in DMSO)
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Product Description

ProductCatalog NumberUnit SizeFormat
Ethidium Homodimer (solid)400101 mgRed solid
Ethidium Homodimer (2 mM in DMSO)400140.5 mLRed solution

Ethidium Homodimer, first developed by Dr. Le Pecq and his colleagues, is a high-affinity fluorescent nucleic acid stain. It binds to both DNA and RNA in a sequence-independent manner and with a >30-fold fluorescence enhancement. The DNA binding of each Ethidium Homodimer covers four base pairs and is believed to occur by intercalation. Because the dye is highly positively charged, it cannot cross cell membranes to stain living cells. It is useful for detecting nucleic acids in solution, or for selectively staining dead cells with damaged plasma membranes.

Biotium offers a high purity grade Ethidium Homodimer I that is not available from other manufacturers. Ethidium Homodimer from other suppliers often contains a high amount (as much as 20%) of inorganic salt that lowers the weight percent purity. We offer Ethidium Homodimer I as a solid (catalog no. 40010) or as a 2 mM solution in DMSO (catalog no. 40014).

Also see Ethidium Homodimer III, which was developed by Biotium as a superior alternative to Ethidium Homodimer I. The absorption and emission spectra are similar, but EthD-III is 45% brighter.

EthD-I is dead cell specific in all cell types, including mammalian cells, bacteria and yeast. See our Cellular Stains Table for more information on how our dyes stain various organisms.

Product Features:

  • λExEm (with DNA) = 528/617 nm
  • λAbs (in H2O, no DNA) = 493 nm
  • Store at 4°C and protect from light
  • C46H50Cl4N8
  • MW: 857


1. Nucleic Acid Res. 23, 2413 (1995).

2. Bioorg Med Chem 3, 701 (1995).


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