What is ratiometric fluorescence used to detect?

Ratiometric fluorescence is used to detect ion concentrations in solution. It involves the use of dual wavelength fluorescent dyes known as ratiometric dyes. The fluorescence excitation of these dyes have two peaks that directly correlate with the intracellular concentration of free ionic calcium. Researchers use ratiometric fluorescence to measure the cellular uptake of free ionic calcium.

Ratiometric calcium indicators have been successfully used to monitor calcium mobilization, image the spatial dynamics of calcium signaling, and in HTS cell-based pharmacological screening of agonist-stimulated and antagonist-inhibited signaling through GPCRs. Among ratiometric calcium indicators, Fura-2 and Indo-1 are the most widely used.