A highly selective and fast-response fluorescent probe for visualization of enzymatic H 2 S production in vitro and in living cells

An o-fluorinated-azido-capped rhodamine probe can react with H2S efficiently and selectively to give large off-on fluorescence enhancement. The probe was used to develop an assay for cystathionine β-synthase acitivity and for in situ visualization of endogenously produced H2S in living cells.