Reduced nicotinamide adenine dinucleotide (NADH) fluorescence for the detection of cell death

NADH/FAD fluorescence spectroscopy/imaging is an extremely useful tool to probe cellular metabolism and has been applied in the clinic such as early cancer detection. Recently, the potential of using NADH/FAD fluorescence as a biomarker to detect cell death has been investigated for development of cancer treatments with higher efficacy. This review aims to provide the updated information in cell death detection using the NADH/FAD fluorescence spectroscopy and imaging based on measurement of the intensity or lifetime of NADH or FAD fluorescence. The response of NADH fluorescence lifetime to metabolic perturbation, hypoxic environment, and anaerobic glycolysis (e.g., in precancerous tissues and stem cells) is also reviewed to discuss the nature and implications of the lifetime change of NADH fluorescence. Further studies are required to understand the actual site and mechanism of NADH binding of a specific death pathway for future successful in vivo detection of cell death using the NADH fluorescence lifetime.