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Propidium Iodide Buffer (50 ug/mL)

Propidium Iodide is a membrane-impermeant nucleic acid intercalator. The dye is commonly used to selectively stain dead cells in a cell population and also used as a counterstain in multicolor fluorescent imaging.

Product Attributes

CAS number


Cellular localization

Nucleus & cytoplasm

Assay type/options

DNA content/cell cycle (flow cytometry), No-wash staining, Real-time imaging

Cell permeability

Membrane impermeant

Apoptosis/viability marker

Dead cell stain




535/617 nm (with DNA)

Catalog #
2 mL
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Product Description

Propidium iodide (PI) is a cell impermeable nucleic acid intercalating dye. Because PI is excluded from viable cells, it can be used to distinguish necrotic or late apoptotic cells with damaged plasma membranes from viable cells or early apoptotic cells with intact cell membranes. After entering cells and binding to DNA and RNA, the fluorescence of PI is enhanced 20- to 30-fold. PI can be used in flow cytometry and fluorescence microscopy. PI is also utilized as a counterstain in multicolor fluorescent imaging, but nuclear-specific staining requires digestion of cellular RNA.

PI 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:

  • 50 ug/mL solution in PBS buffer
  • Orange/red liquid
  • Store at 4°C and protect from light
  • λExEm (DNA-bound) = 535/617 nm
  • λExEm (no DNA) = 493/636 nm
  • C27H34I2N4
  • MW: 668.4
  • [25535-16-4]


We offer PI in a variety of formulations and in conjunction with our fluorescently labeled Annexin V.

Propidium Iodide Products


Unit Size

Catalog Number

Propidium Iodide, 100 mg100 mg40016
Propidium Iodide, 1 mg/mL in water10 mL40017
Propidium Iodide Buffer, 50 ug/mL2 mL40048
CF488A Annexin V and PI Apoptosis Kit100 assays30061

Ethidium homodimer III and 7-AAD are alternative dead-cell selective stains. Also see our Live-or-Dye™ Fixable Viability Staining Kits.




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