Fluo-4 AM

Fluo-4 AM (CAS: 273221-67-3) is a fluorescent calcium indicator widely utilized in biomedical research for intracellular calcium concentration measurement. This acetoxymethyl ester derivative readily diffuses across cell membranes and is hydrolyzed intracellularly by esterases, generating the calcium-sensitive fluorescent dye Fluo-4. Binding of Fluo-4 to cytosolic Ca2? ions induces a significant increase in fluorescence intensity, enabling precise real-time calcium monitoring. Structurally derived from Fluo-3 AM by substituting chlorine with fluorine, Fluo-4 AM exhibits quicker loading kinetics and approximately doubled fluorescence intensity upon excitation at 488 nm. It finds extensive application in cell signaling, functional assays, and pharmacological assessments of calcium-dependent processes.

Fluo-4 AM is one of the most common probes for detecting Ca²⁺. Fluo-4 AM is an acetoxymethyl (AM) ester derivative of Fluo-4 that can penetrate cell membranes and be cleaved by intracellular esterase to form Fluo-4. Fluo-4 can remain in cells and bind to intracellular Ca²⁺, then emit bright fluorescence. Fluo-4 AM is an analog of Fluo-3 AM with two chlorine substituents replaced by fluorines. This modification results in increased fluorescence excitation at 488 nm and a greater signal level for the image. In addition, the fluorescence produced by Fluo-4 binding Ca²⁺ is at least 100 folds stronger than UV-excited probes (Fura-2 and Indo-1). This reagent is provided as a 2 mM stock solution in DMSO.