A dicyanoisophorone-based near-infrared fluorescent probe (NIR-NP) was successfully designed for hydrogen sulfide (H2S) detection. 7-Nitro-1,2,3-benzoxadiazole (NBD) amine, an electron-withdrawing group, was applied to quench the fluorescence of dicyanoisophorone-based fluorescent dyes and could be removed by H2S-specific thiolysis of an NBD amine bond, leading to a significant fluorescence turn-on response. The probe could quantitatively detect H2S with a lower detection limit (0.03 μM) in vitro and in living cells. The probe with a large Stokes shift (186 nm) showed a high selectivity to H2S in the presence of other biothiols, including glutathione, homocysteine, and cysteine. Moreover, the probe was successfully applied to image endogenous H2S in different tumor cells and in liver tissues. The excellent properties of the probe and its applications in cell and tissue imaging indicated its potential for further exploration and application of H2S in the pathophysiology of cancers and even in the diagnosis of H2S-related diseases.
The thiolysis of 7-nitro-1,2,3-benzoxadiazole amine (NBD-A) paves the way for specific sensing of H 2 S over biothiols and real-time imaging in living organisms. Rational fabrication of NBD-A-based probe with ratiometric mode and two-photon excitation is highly appealing to achieve high quality bioimaging. In this work, the NBD-A molecules are assembled with poly(9,9-dioctylfluorenyl-2,7-diyl) polymer nanoparticles , defined as NBD@PFO, to construct two-photon ratiometric probes for H 2 S detection through the fluorescence resonance energy transfer (FRET). For the construction of NBD@PFO nanohybrids , polymer nanoparticles are employed as the NBD-A molecular vehicle, energy donor and two-photon absorber, while NBD-A is served as the response unit and energy acceptor. Taking advantages of NBD-A and polymer nanoparticles, the obtained NBD@PFO probes exhibit high selectivity, fast response (<5 s), ratiometric detection and two-photon excitation. Our results indicate that NBD@PFO nanohybrids are successfully applied for monitoring of H 2 S concentration in living cells and zebrafish, exhibiting great potential of polymer nanoparticles to improve the imaging capability of an organic small molecular probe .
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