Calcium is an important second messenger in biological systems controlling many aspects of cellular function and has been used to produce rheological changes in pectin and alginate hydrogels. Release of calcium with light has several distinct advantages including that light can be directed making the area of release highly specific, as well as being a rapid and easily controlled. Previous photorelease mechanisms include the photochemical scission of a nitrophenyl derivatized calcium chelators such as EGTA. Our study involves the release of calcium through an electron abstraction mechanism using an electron accepting sensitizer and a calcium chelator EDTA. The sensitizers that were investigated consisted of riboflavin, riboflavin tetraacetate,and several anthraquinone sulfonic acid derivatives. The excited state sensitizers accepts an electron from EDTA causing the degradation of EDTA and subsequent calcium release at acidic to basic pHs. Experimental evidence of calcium release and its mechanism include: HPLC, UV-VIS assays and gelation studies.

Directed release of EDTA bound calcium through photoinduced electron transfer

245th National Meeting (2013)

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