Product Description: An intercalating agent and a fluorescent molecule with a molecular mass of 668.4 Da that can be used to stain DNA. When excited by 488nm of laser light, it can be detected with 562-588nm band pass filter. Flow cytometry is used to evaluate cell viability or DNA content in cell cycle analysis. It can be used to differentiate necrotic, apoptotic and normal cells. Propidium iodide is the most commonly used dye to quantitatively assess DNA content.

Propidium iodide (PI) binds to DNA by intercalating between the bases with little or no sequence preference and with a stoichiometry of one dye per 4–5 base pairs of DNA. PI also binds to RNA, necessitating treatment with nucleases to distinguish between RNA and DNA staining. Once the dye is bound to nucleic acids, the fluorescence is enhanced 20- to 30-fold, the fluorescence excitation maximum is shifted ~30–40 nm to the red and fluorescence emission maximum is shifted ~15 nm to the blue. Although its molar absorptivity (extinction coefficient) is relatively low, PI exhibits a sufficiently large Stokes shift to allow simultaneous detection of nuclear DNA and fluorescently-labeled antibodies, provided the proper optical filters are used. PI is suitable for fluorescence microscopy, confocal laser scanning microscopy, flow cytometry, and fluorometry.