NADH- induced “kick-on” fluorescent probe validates crosstalk with redox regulator GSH

Mitochondrial Targetable Turn-On Fluorescent Probe for Fast Detection of NAD(P)H in Living Cells and In Vivo

“…Recently, there has been notable emphasis on the advancement of NAD(P)H fluorescent probes. These probes utilize different recognition units such as quinolinium, pyridinium, resazurin, benzophenoxazine, and quinone. , 1-methylquinolinium compounds, especially those containing an electron-accepting group in the third position, are prone to being reduced by NADH, leading to the major production of 1-methyl-1,4-dihydroquinoline is widely acknowledged. − Therefore, quinolinium emerges as the recognition unit that is frequently utilized in these purposefully created probes. − Although considerable progress has been achieved in the field of NAD(P)H probes, there remain a number of constraints that require attention and resolution. These drawbacks include the on–off mechanism, which may not be optimal for certain applications, a sluggish reaction rate, limited sensitivity, a lack of noticeable changes in fluorescence, and short emission wavelengths (Table S1).…”

Thiophene-based organic dye with large Stokes shift and deep red emission for live cell NAD(P)H detection under varying chemical stimuli

“…Recently, fluorescent probes combined with fluorescence microscopy have been reported to allow monitoring of NADH levels in live cells because of their specificity, sensitivity, operation simplicity, superior biocompatibility, and available imaging reagents with fluorescence ranging from visible to near-infrared regions. [5][6][7][8][9][10][11][12][13][14][15][16][17][18] Since NADH is a fluorophore with an absorption peak at 350 nm and a fluorescence peak at 460 nm, 19,20 it is very crucial to develop fluorescent probes with deep red and near-infrared fluorescence to void fluorescence interference from the NADH fluorophore, as these probes can emit light at longer wavelengths that are less likely to overlap with NADH's fluorescence. Connecting a 1-methylquinolinium acceptor to different electron-withdrawing acceptors is a reported strategy to develop deep red and near-infrared fluorescent probes for NADH detection.…”

“…Several probes using this strategy have been reported in the literature. [5][6][7][8][9][10][11][12][13][14][15][16][17][18] The present paper describes a low-cost method to create two deep red-emitting cyanine dyes (probes A and B) for detecting NADH. Thiophene and 3,4-ethylenedioxythiophene were used as connection bridges between 1-methyl-1,4-dihydroquinoline and formyl electronwithdrawing acceptors, resulting in large Stokes shifts (Scheme 1).…”

Cellular and Intravital Imaging of NAD(P)H by a Red-Emitting Quinolinium-Based Fluorescent Probe that Features a Shift of Its Product from Mitochondria to the Nucleus

“…Fluorescence imaging based on small-molecule fluorescent probes has emerged as one of the most powerful techniques to monitor targets and biological processes in complicated living systems with high temporal and spatial resolution. − Thus, the past couple of years have witnessed much effort toward the development of NAD­(P)H fluorescent probes based on various recognition units, including quinolinium, pyridium, resazurin, benzophenoxazine, and quinone. , It is well known that 1-methylquinolinium compounds with electron-withdrawing substituents in the 3-position are readily reduced by NADH analogues to yield 1-methyl-1,4-dihydroquinoline predominantly, − and quinolinium thereby stands out as the most used recognition unit among these designed probes. − Despite the progress in developing NAD­(P)H probes, there still exist a few limitations, such as ON–OFF mechanism, slow response rate, dull sensitivity, inapparent fluorescent change, and short-emission wavelength (Table S1). Additionally, to our knowledge, relatively fewer near-infrared (NIR) (650–900 nm) emission fluorescent probes for NAD­(P)H have been reported. ,, NIR fluorescent probes are more favorable for intravital imaging of target analytes in complicated biological systems due to their minimum photodamage to samples, deep tissue penetration, and minimum interference from background autofluorescence. , Therefore, developing NIR fluorescent probes with excellent properties for intravital imaging of NAD­(P)H is still quite challenging but extremely desirable.…”