DAF-FM diacetate

DAF-FM diacetate is a cell-permeable, fluorescent probe for the detection and bioimaging of nitric oxide (NO), with excitation/emission maxima of 495/515 nm. It passively diffuses across cellular membranes and, once inside cells, is then deacetylated by intracellular esterases to DAF-FM [1].

The fluorescence quantum yield of DAF-FM was ~ 0.005, but increased about 160 folds, to ~ 0.81, after reacting with NO [1]. DAF-FM fluorescence with NO is time-dependent. In a reaction mixture containing 190 nM NO or 380 nM NO, and 1 μM DAF-FM,  relative fluorescence (493 nm excitation, 514 nm emission) increased rapidly during the first 10 min of incubation and reached a steady slow increase at 40 min. After 60 min, there was a minimal (~ 15%) increase in fluorescence [2].

DAF-FM diacetate exhibited several advantages over the NO probe, DAF-2 diacetate. When the pH values exceeded 5.5, the spectra of the NO adduct of DAF-FM become independent. Compared with the NO adduct of DAF-2, the combination of NO and DAF-FM was significantly more photostable. In addition, the NO detection limit of DAF-FM was ~ 3 nM, more sensitive than that of DAF-2 (~ 5 nM) [1, 3].

References:

[1]. Kojima H, Urano Y, Kikuchi K, et al. Fluorescent indicators for imaging nitric oxide production. Angewandte Chemistry International Edition English, 1999, 38(21): 3209-3212.

[2]. Vitecek J, Reinohl V, Jones R L. Measuring NO production by plant tissues and suspension cultured cells. Molecular Plant, 2008, 1(2): 270‐284.

[3]. Kojima H, Nakatsubo N, Kikuchi J, et al. Detection and imaging of nitric oxide with novel fluorescent indicators: Diaminofluoresceins. Analytical Chemistry, 1998, 70(13): 2446-2453.