An ICT-FRET-based ratiometric fluorescent probe for hydrogen polysulfide based on a coumarin-naphthalimide derivative.

[Display omitted] • An ICT-FRET-based fluorescent probe for the ratiometric detection of H 2 S n has been reported. • The probe displays high sensitivity and high selectivity for H 2 S n. • The probe had been applied for the ratiometric detection of H 2 S n in A549 cells. Hydrogen polysulfide (H 2 S n , n > 1), as one of the important members of reactive sulfur species (RSS), plays a vital part in the processes of both their physiology and pathology. In this work, a ratiometric fluorescent probe for H 2 S n had been designed and prepared based on the combination mechanism of intramolecular charge transfer (ICT) and fluorescence resonance energy transfer (FRET). The probe chose a coumarin derivative as the energy donor, a naphthalimide derivative as the energy acceptor and 2-fluoro-5-nitrobenzoate as the H 2 S n recognition group. When H 2 S n was not present in the system, the ICT process of the naphthalimide acceptor was inhibited and the FRET process from the coumarin donor to the naphthalimide acceptor was turned off. When H 2 S n was added, both ICT and FRET occurred due to the nucleophilic substitution-cyclization reactions between the probe and hydrogen polysulfide. In addition, the ratio value of the emission intensities at 550 nm and 473 nm (I 550 nm/I 473 nm) of this probe had a good linear relationship with H 2 S n concentration in the range of 6.0 × 10-7-5.0 × 10-5 mol·L-1, and a detection limit of 1.8 × 10-7 mol·L-1 was obtained. The developed probe had high selectivity and sensitivity, as well as good biocompatibility. Additionally, the probe had been used to successfully image both indigenous and exogenous hydrogen polysulfide in A549 cells using confocal microscope. [ABSTRACT FROM AUTHOR]