A membrane permeable fluorescent Ca2+ probe based on bis-BODIPY with branched PEG.

A new class of Ca2+ probes is developed based on PEG-BODIPY-BAPTA conjugates. These newly formed probes with BAPTA acid exhibit high sensitivity and selectivity for Ca2+ over other metal ions, can pass through the cell membranes of living cells without special procedures, and can monitor changes in the intracellular Ca2+ signal.