A new strategy to construct a FRET platform for ratiometric sensing of hydrogen sulfide

We introduce a new FRET strategy to construct a ratiometric fluorescent H2S sensor. The ratio emission signal of the coumarin-naphthalimide dyad is modulated by the FRET process, which works in coordination with the ICT mechanism. The FRET process on/off is controlled through tuning the overlap level of the donor emission spectrum with the acceptor absorption via modulation of the acceptor fluorophore absorption wavelength. CN-N-3 was applied to visualize both the intracellular exogenous and endogenous H2S through blue and green emission channels.