AAT Bioquest

What is the alternative to propidium iodide for dead cell staining?

Posted July 12, 2022


7-AAD is the most common alternative to propidium iodide for dead cell staining.  There are several reasons for this. First, it is like propidium iodide(PI) in the sense that it also binds to double stranded DNA. A slight difference is that it interlocks to the G-C rich regions of the DNA, while PI interlocks non-specifically to the DNA base pairs. Additionally, both PI and 7-AAD have the same excitation wavelength of 488nm. Their emission wavelengths are slightly different, with PI’s at 617nm, and 7-AAD’s at 647 nm. DAPI is another alternative to propidium iodide, but it is not the most common alternative. This dye interlocks to the A-T rich regions of the DNA, and it also binds to RNA. DAPI’s excitement wavelength is 358 nm, and its emission wavelength is 461 nm. It can be concluded that based on its properties DAPI has less similarities than 7-AAD, so that’s why it is not the first alternative. This is due to its binding capabilities with RNA and having a higher emission and excitement wavelength difference than 7-AAD.  

Additional resources

Comparison between propidium iodide and 7-amino-actinomycin-D for viability assessment during flow cytometric analyses of the human sperm acrosome

Live or Dead™ Cell Viability Assay Kit *Green/Red Dual Fluorescence*