SBFI (FIG. 2.8) s an ultraviolet (340 and 380 nm) excitation ratiometric Na+ indicator. It suffers from inefficient loading through the AM form and from relatively low brightness. Although SBFI has been the best available Na+ indicator up to now, most scientists will want to switch to Asante Natrium Green for greatly improved performance.

SBFI molecular structure

Figure 2.8 SBFI


Excitation: 340/380 nm (excitation maxima at 517 nm)

Emission: 505 nm

kd: 4 mM

Solubility: H20 (salt form)  DMSO (AM form)

Molecular Weight: 1127 g/mol

SBFI (AM) absorbs maximally at 381 nm with εmax = 44000/(cm⋅M). The solvent of choice for making AM stock solution is DMSO. [It is important to note that, upon intracellular hydrolysis intracellularly, the AM ester is transformed into the active, ionic form of SBFI, which absorbs maximally at 339 nm with εmax = 45000/(cm⋅M) .]

SBFI (K+ salt) absorbs maximally at 339 nm with εmax = 45000/(cm⋅M). Cocentrated stock solutions can be made in H2O.



Asante NaTRIUM Green-2

Asante Potassium Green-2

Asante Calcium Green

Asante Calcium Red