SBFI AM

SBFI AM is a membrane-permeant, fluorescent Na+ indicator dye. It is selective for Na+ over K+ with Kd values of 20 and 120 mM for these ions, respectively. [1]Increasing concentration of Na+ increases the ratio of excitation efficiency at 330-345 nm to that at 370-390 nm with emission collected at 450-550 nm. [1]  Therefore, ratio fluorometry and imaging can be performed with the same wavelengths. SBF AM is suitable for single intracellular dye injection and is typically used for high-resolution measurements of Na+ concentration in intact tissue through two-photon confocal imaging.[2]

Reference:
[1]. Minta, A., and Tsien, R.Y. Fluorescent indicators for cytosolic sodium. The Journal of Biological Chemisty 264(32), 19449-19457 (1989).
[2]. Meier, S.D., Kovalchuk, Y., and Rose, C.R. Properties of the new fluorescent Na+ indicator CoroNa Green: Comparison with SBFI and confocal Na+ imaging. Journal of Neuroscience Methods 155(2), 251-259 (2006).