A quinoline-based indicator for NAD(P)H multimodal detection in vitro and in vivo: Spectrophotometry and visible near-infrared dual-channel lighting-up fluorescence imaging

Nicotinamide adenine dinucleotide (phosphate) (NAD(P)H/NAD(P)+) is crucial for oxidation-reduction equilibrium in all living cells, and disturbance of NAD(P)H/NAD(P)+ indicates many diseases. To accurately detect and track NAD(P)H in vitro and in vivo, we have developed a small organic dye (Rh-QL) based on intramolecular charge transfer (ICT) mechanism for multimodally detecting NAD(P)H by visible and near-infrared (Vis-NIR) dual-channel lighting-up fluorescence and by near-infrared spectrophotometry. This quinoline-based Indicator showed high selectivity and sensitivity toward NAD(P)H with a large redshift of absorption and dual-channel emissions at 580 nm and 750 nm, spatiotemporally and synchronously. For liquid samples, Rh-QL succeeded to screen NAD(P)H-related G6PD enzymatic activity by responsive absorption at 710 nm. In living cells, Rh-QL exhibited a good bio-compatibility and remarkable mitochondrial-targeted capacity to visualize intracellular endogenous and exogenous NAD(P)H variation utilizing Vis-NIR dual-channel fluorescence. In vivo, the near-infrared fluorescence was applied to differentiate tumor-bearing mice by NAD(P)H imaging. Moreover, “glycolysis” in both cancer cells and tumors of mice were traced to produce extra NAD(P)H using Rh-QL. As the first Vis-NIR dual-channel lighting-up probe to multimodally detect and track NAD(P)H in vitro and in vivo, it is appealing for high efficiency in understanding NAD(P)H-related physiological and pathological processes of disease diagnosis and therapy.