Ratiometric imaging of intracellular Mg²⁺ dynamics using a red fluorescent turn-off probe and a green fluorescent turn-on probe

In this work, we developed a red fluorescent turn-off Mg²+ probe with high Mg²⁺ selectivity. The quenching response to Mg²⁺ in combination with a green fluorescent turn-on Mg²+ probe enabled a ratiometric imaging of the changes in intracellular Mg²⁺ concentration. This ratiometric imaging system significantly enhanced the detection sensitivity of intracellular Mg²⁺ fluctuations in comparison with a conventional ratiometric Mg²⁺ sensing system, thus leading to a valuable technique for visualizing small change in intracellular Mg²⁺ concentration.