Mitochondria-targetable red-emitting probe for real-time fluorescence monitoring of NAD(P)H in live cells

We have developed a mitochondria-targetable and red-emitting probe (1) that allows for the quantitative analysis of mitochondrial NAD(P)H in live human cells. Probe 1 is non-fluorescent and gets reduced in the presence of NAD(P)H to emit a strong fluorescence. This probe is highly selective to NAD(P)H over various potential biological interferants such as redox species, metals, anions, and other biomolecules. In addition, confocal microscopic images revealed the predominant accumulation of probe 1 into the mitochondria of human breast cancer cells (MDA-MB-231), as evident from the red fluorescence in response to NAD(P)H activity in glucose-treated cells as NAD(P)H induction model vs. cyanide 4-(trifluoromethoxy)phenylhydrazone-treated cells as NAD(P)H depletion model. Probe 1 can be used to differentiate between cancer (MDA-MB-231) and normal cells (NIH-3T3) based on mapping mitochondrial NAD(P)H-dependent fluorescence intensity. Probe 1 will be useful for various applications, ranging from elucidation of biological pathways to pathological diagnosis.