AAT Bioquest

Does Propidium Iodide specifically bind to dead cells?

Posted May 18, 2020


Yes. Propidium iodide (PI) is a membrane impermeable dye that is generally exclude by live cells with intact membranes. However, it can penetrate the damaged membranes of dead cells, and stain the intracellular double stranded DNA molecules by intercalating between the bases.

The excitation/emission maximum of PI bound to DNA is 535 nm/617 nm. Such a large Stokes shift makes it very useful to combine with other fluorochromes in flow cytometry, such as fluorescein isothiocyanate (FITC) and phycoerythrin (PE) who are also excited with 488 nm laser.

Additional resources

Propidium iodide *CAS 25535-16-4*

Lecoeur, H. (2002). Nuclear Apoptosis Detection by Flow Cytometry: Influence of Endogenous Endonucleases. Experimental Cell Research, 277(1), 1–14. doi:10.1006/excr.2002.5537