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

As a vital signaling molecules, hydrogen sulfide (H2S) with abnormal concentrations is correlated with many diseases. Therefore, development of novel assays for quantitative and selective detection of H2S is important. Herein, we synthesized a host-guest metal-organic framework (MOF), i.e., RhB/UiO-66-N3 (here, RhB means rhodamine B) by a mildly and simply way, as reaction-based ratiometric fluorescent nanosensor for selective detection and intracellular imaging of H2S. In the presence of H2S, the RhB/UiO-66-N3 exhibits dual emissions at 425 nm and 575 nm under irradiation of single excitation wavelength. The blue fluorescence at 425 nm (F425) is attributed to the H2S-mediated biorthogonal reduction of azide to amine, and the red fluorescence at 575 nm (F575) originating from RhB is served as an internal reference. With increasing concentrations of H2S, the intensity of blue fluorescence increases while the intensity of red fluorescence has no obvious change. With F425/F575 as readout, turn-on and ratiometric fluorescence detection of H2S was achieved with good selectivity and sensitivity. Interestingly, RhB/UiO-66-N3 can be tuned from microscale to nanoscale sizes, and endows high stability under physiological conditions. The exogenous and endogenous H2S in live cells has been further targeted and imaged, demonstrating its considerable potential for extensive applications.