The MitoLight™ Apoptosis Detection Kit utilizes a lipophilic cation, termed as MitoLight™, as a mitochondrial activity marker. MitoLight™ is a mitochondrial dye that stains mitochondria in living cells in a membrane potential-dependent fashion. The monomer is in equilibrium with so-called J-aggregates, which are favored at higher dye concentration or higher mitochondrial membrane potential.
MitoLight™ partitions differently in healthy cells than in apoptotic cells. Therefore, it has been possible to use a fluorescence ratioing technique to study mitochondrial membrane potentials.