Is Calcein, AM toxic to cells?

Calcein, AM is a cell-permeant dye principally used for determining cell viability. Once inside the cell, non-fluorescent Calcein, AM is hydrolyzed by non-specific intracellular esterases into a green fluorescent Calcein dye, which is negatively charged and well-retained within the cytoplasm. Calcein, AM has been used for studies of enzymatic activity, cell membrane integrity, and long-term cell tracking due to its low cellular toxicity. 

It is important to note that for certain cell lines and experimental conditions, relatively high concentrations of Calcein, AM can be toxic to cells.

• For fluorescence-based imaging we recommended the final concentration of Calcein, AM be 4 to 5 µM (with culture medium) or 2 µM (in HHBS buffer or buffer of your choice with culture medium removed).
• For flow cytometry we recommend the final concentration of Calcein, AM be 500 nM to 1 µM.

The table below shows the range of available Calcein and CytoCalcein™ cell viability dyes, their excitation and emission maxima, and instrument specifications to assist you in selecting the best dye for determining cell viability.