Chemical Indicators
Chemical indicators are small molecules that can chelate calcium ions. All these molecules are based on an EGTA homologue called BAPTA, with high selectivity for calcium (Ca2+) ions versus magnesium (Mg2+) ions.
This group of indicators includes fura-2, indo-1, fluo-3, fluo-4, Calcium Green-1.
These dyes are generally used with the chelator carboxyl groups masked as acetoxymethyl esters, in order to render the molecule lipophilic and to allow easy entrance into the cell. Once the indicator is in the cell, cellular esterases will free the carboxyl and the indicator will be able to bind calcium.
Read more about this topic: Calcium Imaging
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