New photolabile BAPTA-based Ca2+ cages with improved photorelease.

The efficient synthesis, physicochemical and photolytical properties of a photoactivable BAPTA-based Ca2+ cage containing two photosensitive o-nitrobenzhydryl groups attached to the aromatic core are described. Ca2+ release in living cells was evaluated. The double substitution with the chromophores caused a significant improvement of the Ca2+ release properties of nitr-T versus singly substituted reported nitr-x derivatives without compromising Ca2+/Mg2+ selectivity or pH insensitivity. Our results demonstrate a general strategy to improve light-triggered Ca2+ release which may result in more efficient, selective, and pH-insensitive photolabile Ca2+ chelators.