Measurement of cell calcium ( review ) methods for the intracellular ca2 + measurement such as aequorin , metallochromic indicators , ion - selective electrodes and fluorescent ca2 + indicators , particularly the fluorescent ca2 + indicators were reviewed in detail . 2 . synthesis of new fluorescence ca2 + indicators and study on their properties tow new fluorescent ca2 + indicators stdin and stdbt have been designed and synthesized and their structures , spectral and biological properties have been studied thoroughly