AAT Bioquest

Propidium Iodide

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Physical properties
Molecular weight668.39
Spectral properties
Extinction coefficient (cm -1 M -1)60001
Excitation (nm)537
Emission (nm)618
Quantum yield0.21
Storage, safety and handling
H-phraseH303, H313, H333
Hazard symbolXN
Intended useResearch Use Only (RUO)
R-phraseR20, R21, R22
StorageFreeze (< -15 °C); Minimize light exposure


Molecular weight
Extinction coefficient (cm -1 M -1)
Excitation (nm)
Emission (nm)
Quantum yield
Propidium iodide (PI) is a red-fluorescent dye widely used for staining and identifying dead cell populations in flow cytometry and fluorescence microscopy.

This product is offered as a 1 mg / mL aqueous solution.

Product Description

PI is a membrane-impermeant dye that selectively binds to DNA by intercalating between nucleic acid bases with minimal sequence specificity. While viable cells with intact membranes exclude PI, it penetrates and stains cells with compromised membranes, such as those undergoing apoptosis or necrosis. PI is optimally excited at 535 nm and emits bright red fluorescence at a maximum wavelength of 617 nm, making it well-suited for detection via flow cytometry or fluorescence microscopy. For multiparametric analysis, PI can be used in combination with other fluorescent markers, such as calcein AM for live/dead cell discrimination or Annexin V FITC to differentiate between apoptotic and necrotic cells.

Key Features

  • High Sensitivity and Specificity, staining cells with compromised membranes, such as apoptotic and necrotic cells, making it a reliable indicator of cell death
  • Bright Fluorescence that is enhanced 20-30 fold upon binding to DNA
  • Multiparametic Capability which can used in conjunction with green fluorescent probes, such as Calcein AM or Annexin V-FITC, for comprehensive cell health analysis
  • Quick and Simple Protocol that requires minimal preparation and hands-on time
  • High-Throughput Adaptability, enabling HTS applications, facilitating large-scale studies and drug discovery research

Mechanism of Action

Due to its inability to penetrate intact cell membranes, PI selectively enters cells with compromised membranes, such as apoptotic or necrotic cells, and intercalates between the base pairs of double-stranded DNA and RNA. This intercalation significantly enhances its red fluorescence, with excitation and emission maxima at approximately 535 nm and 617 nm, respectively. PI is frequently employed in flow cytometry and fluorescence microscopy to discriminate live and dead cell populations and to quantify DNA content for cell cycle phase distribution. In apoptosis assays, PI is often used in conjunction with Annexin V to distinguish between apoptotic and necrotic cells, with Annexin V-positive/PI-negative cells indicating early apoptosis and Annexin V-positive/PI-positive cells indicating late apoptosis or necrosis. Given its potential mutagenicity, proper handling with personal protective equipment is essential.


Common stock solution preparation

Table 1. Volume of Water needed to reconstitute specific mass of Propidium Iodide to given concentration. Note that volume is only for preparing stock solution. Refer to sample experimental protocol for appropriate experimental/physiological buffers.

0.1 mg0.5 mg1 mg5 mg10 mg
1 mM149.613 µL748.066 µL1.496 mL7.481 mL14.961 mL
5 mM29.923 µL149.613 µL299.226 µL1.496 mL2.992 mL
10 mM14.961 µL74.807 µL149.613 µL748.066 µL1.496 mL

Molarity calculator

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Spectral properties

Extinction coefficient (cm -1 M -1)60001
Excitation (nm)537
Emission (nm)618
Quantum yield0.21

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