Visible light initiated release of calcium ions through photochemical electron transfer reactions.

Photolysis of anthraquinone or flavin photosensitizers in the presence of calcium EDTA complexes results in decomposition of the EDTA complex, releasing free Ca2+. In the case of the flavin sensitizers, it is shown that millimolar concentrations of Ca2+ can be released using visible light (>440 nm) and with quantum yields as high as 0.31. The utility of this system is further demonstrated by in situ photogelation of an alginate solution.