RhB/UiO-66-N3 MOF-based ratiometric fluorescent detection and intracellular imaging of hydrogen sulfide.

• A reaction-based ratiometric fluorescent nanosensor for H 2 S is established with RhB/UiO-66-N 3 MOF. • The size of RhB/UiO-66-N 3 can be easily tuned to nanoscale for direct in vivo evaluation. • RhB/UiO-66-N 3 endows good stability, selectivity and reliability for H 2 S analysis under physiological conditions. • Exogenous and endogenous H 2 S in live cells has been successfully targeted and imaged. As a vital signaling molecules, hydrogen sulfide (H 2 S) with abnormal concentrations is correlated with many diseases. Therefore, development of novel assays for quantitative and selective detection of H 2 S is important. Herein, we synthesized a host-guest metal-organic framework (MOF), i.e., RhB/UiO-66-N 3 (here, RhB means rhodamine B) by a mildly and simply way, as reaction-based ratiometric fluorescent nanosensor for selective detection and intracellular imaging of H 2 S. In the presence of H 2 S, the RhB/UiO-66-N 3 exhibits dual emissions at 425 nm and 575 nm under irradiation of single excitation wavelength. The blue fluorescence at 425 nm (F 425) is attributed to the H 2 S-mediated biorthogonal reduction of azide to amine, and the red fluorescence at 575 nm (F 575) originating from RhB is served as an internal reference. With increasing concentrations of H 2 S, the intensity of blue fluorescence increases while the intensity of red fluorescence has no obvious change. With F 425 /F 575 as readout, turn-on and ratiometric fluorescence detection of H 2 S was achieved with good selectivity and sensitivity. Interestingly, RhB/UiO-66-N 3 can be tuned from microscale to nanoscale sizes, and endows high stability under physiological conditions. The exogenous and endogenous H 2 S in live cells has been further targeted and imaged, demonstrating its considerable potential for extensive applications. [ABSTRACT FROM AUTHOR]