Application of Organic Small-Molecule Fluorescent Probes for NAD(P)H Imaging and Detection.

Reduced nicotinamide adenine dinucleotide (NADH) and its phosphate ester form, nicotinamide adenine dinucleotide phosphate (NADPH), function as essential electron carriers in cellular systems and participate in a wide range of fundamental physiological processes. Moreover, metabolic dysregulation of NAD(P)H has been increasingly implicated in the pathogenesis of various human diseases, such as tumors and neurodegenerative diseases. Real-time monitoring of dynamic NAD(P)H levels in living cells and organisms is essential for elucidating relevant physiological processes and uncovering mechanisms underlying disease progression. Fluorescent probes serve as portable tools for the real-time detection of NAD(P)H, enabling the assessment of physiological and pathological conditions owing to their high sensitivity, superior selectivity, and noninvasive characteristics. Currently, different types of fluorescent probes derived from small-molecule fluorophores, including fluorescein, rhodamine, coumarin, naphthylamide, and resazurin derivatives, have been developed for the detection of NADH and NADPH within biological systems. This review summarizes the recent progress in the field of NADH and NADPH fluorescent probes utilizing different small molecule fluorophores, and offers a concise discussion of their current limitations.