Fluo-3 is a fluorescent calcium indicator commonly used in flow cytometry (FC) and cell-based experiments to detect changes in intracellular calcium levels. Its absorption maximum at 506 nm makes it compatible with excitation at 488 nm by argon-ion laser sources. Fluo-3 provides intense fluorescence upon binding calcium, detected at a maximum emission at 526 nm which can be monitored by FL1 (green, 525 nm band pass) sensors in flow cytometry. Fluo-3 AM is an acetoxymethyl (AM) ester of fluo-3. This form, unlike fluo-3, is cell permeable and readily taken up by living cells, whereupon the AM moiety is enzymatically removed to produce fluo-3.
