7-AAD is a fluorescent DNA binding dye that is membrane impermeant and therefore generally excluded from viable cells.  The dye is excluded by live cells and early apoptotic cells, but stains necrotic and late apoptotic cells with compromised membrane integrity.    7-AAD/DNA complexes can be excited at 488 nm with an argon-ion laser, and has a large Stokes shift with an emission maxima of 647 nm. 7-AAD intercalates selectively at GC-rich regions of DNA, which makes the dye useful for chromosome banding studies. 7-AAD can be used in multicolor fluorescence microscopy and flow cytometry.    &lamba;Ex/&lamba; Em(DNA) = 546/647 nm (7-AAD can also be excited by the 488 or 532 laser lines)  Orange red solid soluble in DMF or DMSO  Store at -20°C and protect from light, especially in solution  C62H87N13O16  MW: 1270.45