AAT Bioquest

What are the commonly used non-fixed cell viability dyes?

Posted January 26, 2023


Commonly used non-fixed viability dyes include: propidium iodide (PI), DAPI, 7-AAD,  DRAQ7, and TO-PRO-3. PI is a fluorescent intercalating dye used to stain both nucleic acids and cells. It binds to DNA by intercalating nonspecifically between the bases. When in a solution, PI has a fluorescence maximum of 493 nm and emission maximum of 636 nm. DAPI is a blue fluorescent DNA dye that displays 20 fold enhancement of fluorescence when binding to AT rich regions in the minor groove of dsDNA. It is excited by the violet (405 nm) laser and is often used as a counterstain in flow cytometry, chromosome staining, and fluorescence microscopy. 7-AAD intercalates with dsDNA and has a high affinity for GC-rich regions. This makes it particularly helpful for chromosome banding studies and is excited by the blue laser line (488 nm). DRAQ-7 is a red fluorescent dye that rapidly stains dsDNA of dead cells. It is excited by wavelengths ranging from 488 to 647 nm, and is ideally excited by red laser lines. When intercalated with dsDNA, its emission maxima 697 nm.  TO-PRO-3 stain is also a red-fluorescent counterstain that penetrates membranes of dead cells. It has an excitation at 642 nm and emission at 661 nm. This dye has an advantage from other dyes because its fluorescence is not obscured by tissue autofluorescence; it also exhibits strong and selective staining of the nucleus in cultured cells.


Additional resources

Comparative Analysis of the Different Dyes' Potential to Assess Human Normal and Cancer Cell Viability In Vitro under Different D/H Ratios in a Culture Medium

Cell Viability Assays

TWO-PRO™ 3 [equivalent to TO-PRO®-3] *5 mM DMSO Solution* *CAS 157199-63-8*