A novel ratiometric emission probe for Ca2+ in living cells

A ratiometric fluorescent probe for Ca2+ based on 1,3,4-oxadiazole derivative has been designed and developed. The probe exhibits a large Stokes shift of 202 nm and a highly selective ratiometric emission response (490/582 nm) to Ca2+ over other metal cations. Additionally, the probe can readily reveal the changes of intracellular Ca2+ concentration in living human umbilical vein endothelial cells.