Nonyl acridine orange is well retained in mitochondria and therefore serves as an effective probe, Track mitochondrial status during cell isolation and after cell fusion. It has been reported that mitochondrial uptake is independent of membrane potential, unlike other mitochondrial probes. Therefore, regardless of whether it is in a charged state, it is toxic at high concentrations and is significantly bound to cardiolipin in all mitochondria. This derivative has been used for mitochondrial flow cytometry analysis, identification of multidrug resistance, and determination of mitochondrial mass changes during apoptosis.