AAT Bioquest

How does DAPI work?

Posted July 22, 2020


DAPI (4?,6-diamidino-2-phenylindole) is a blue DNA binding dye with a preference for A-T rich regions, whose quantum yield is significantly enhanced when bound to double-stranded DNA. Although DAPI can pass through an intact cell membrane, it is rarely used for live cell staining because the concentration needed is very high. Therefore, DAPI is generally considered excluded from viable cells, but can penetrate cell membranes of dead or dying cells and bind their intracellular nucleic acids. When bound to DNA, DAPI shows bright blue fluorescence, with excitation/emission maximum of 358/461 nm. DAPI is widely used in fluorescence microscopy and flow cytometry for cell viability measurement and DNA content analysis.

Additional resources

DAPI [4,6-Diamidino-2-phenylindole, dihydrochloride] *CAS 28718-90-3*

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

Cell Meter™ Cell Viability Assay Kit *Blue Fluorescence*

Riss, T. L., Moravec, R. A., Niles, A. L., Duellman, S., Benink, H. A., Worzella, T. J., & Minor, L. (2016). Cell viability assays. In Assay Guidance Manual [Internet]. Eli Lilly & Company and the National Center for Advancing Translational Sciences.

Stoddart, M. J. (2011). Cell viability assays: introduction. In Mammalian cell viability (pp. 1-6). Humana Press.