Biotium offers a wide range of calcium indicator dyes, including 
Fluo-4 AM Ester, a bright and cell permeable dye that is used for high-throughput screening.
The calcium indicator dyes vary in their calcium dissociation constant (Kd), color and brightness. The AM ester versions are cell permeable, and hydrolyzed by intracellular esterases to release the fluorescent dye. See our complete selection of 
Calcium & Other Ion Indicators, or download the 
Ion Indicator Brochure to learn more.