PBFI AM (Synonyms: Potassium-binding Benzofuran Isophthalate Acetoxymethyl ester)

PBFI AM is a cell-permeable, potassium-sensitive fluorophore used to measure potassium changes in cells and intracellular compartments.[1] [2] As PBFI AM enters cells, it is hydrolyzed by intracellular esterases to produce PBFI. The affinity of PBFI for potassium is sodium-dependent (Kd = 44 and 5.1 mM with or without sodium, respectively). [3] Absorption and emission maxima are 336 and 480-557 nm, respectively.[4] [5]

Reference:
[1]. Grieshaber, S., Swanson, J.A., and Hackstadt, T. Determination of the physical environment within the Chlamydia trachomatis inclusion using ion-selective ratiometric probes. Cell. Microbiol. 4(5), 273-283 (2002).
[2]. Ljubkovic, M., Marinovic, J., Fuchs, A., et al. Targeted expression of Kir6.2 in mitochondria confers protection against hypoxic stress. J. Physiol. 577(Pt 1), 17-29 (2006).
[3]. Halperin, S.J., and Lynch, J.P. Effects of salinity on cytosolic Na+ and K+ in root hairs of Arabidopsis thaliana: In vivo measurements using the fluorescent dyes SBFI and PBFI. J. Exp. Bot. 54(390), 2035-2043 (2003).
[4]. Sabnis, R.W. Handbook of biological dyes and stains: Synthesis and industrial applications. (2010).
[5]. Jezek, P., Mahdi, F., and Garlid, K.D. Reconstitution of the beef heart and rat liver mitochondrial K+/H+ (Na+/H+) antiporter. Quantitation of K+ transport with the novel fluorescent probe, PBFI. J. Biol. Chem. 265(18), 10522-10526 (1990).