Cell biology 

Ethidium Homodimer I, 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 can not cross cell membranes to stain living cells. However, it is very useful to detect nucleic acids in solution, or cells with disintegrated cell membranes. Biotium offers ethidium homodimer I in a ready-to-use form.

• λ_Ex/λ_Em (with DNA) = 528/617 nm
• λ_Abs  (in H₂O, no DNA) = 493 nm
• Red solution
• Store at 4°C and protect from light