Design of a facile fluorescent probe with a large Stokes shift for hydrogen peroxide imaging in vitro and in vivo

A fast-responsive fluorescent probe based on a styrylcoumarin dye for visualizing hydrogen sulfide in living MCF-7 cells and zebrafish

As a vital antioxidant molecule, H₂S can make an important contribution to regulating blood vessels and inhibiting apoptosis when present at an appropriate concentration. Higher levels of H₂S can interfere with the physiological responses of the respiratory system and central nervous system carried out by mammalian cells. This is associated with many illnesses, such as diabetes, mental decline, cardiovascular diseases, and cancer. Therefore, the accurate measurement of H₂S in organisms and the environment is of great significance for in-depth studies of the pathogenesis of related diseases. In this contribution, a new coumarin-carbazole-based fluorescent probe, COZ-DNBS, showing a rapid response and large Stokes shift was rationally devised and applied to effectively sense H₂S in vivo and in vitro. Upon using the probe COZ-DNBS, the established fluorescent platform could detect H₂S with excellent selectivity, showing 62-fold fluorescence enhancement, a fast-response time (<1 min), high sensitivity (38.6 nM), a large Stokes shift (173 nm), and bright-yellow emission. Importantly, the probe COZ-DNBS works well for monitoring levels of H₂S in realistic samples, living MCF-7 cells, and zebrafish, showing that COZ-DNBS is a promising signaling tool for H₂S detection in biosystems.

The probe COZ-DNBS displayed excellent selectivity, a fast response, high sensitivity, a large Stokes shift, and bright-yellow emission in response to H₂S.

A neoteric dual-signal colorimetric fluorescent probe for detecting endogenous/exogenous hydrogen peroxide in cells and monitoring drug-induced hepatotoxicity

Hydrogen peroxide (H₂O₂), one of the most important reactive oxygen species (ROS), can be generated endogenously in the liver and has been deemed as a biomarker for evaluating drug-induced liver injury (DILI). Therefore, it is highly crucial to construct an effective method for detecting H₂O₂ in the liver in order to evaluate DILI. Herein, a neoteric dual-signal colorimetric fluorescent probe XH-2 for sensing hydrogen peroxide was engineered and synthesized. Borate was grafted as a specific recognition group onto the fluorophore XH-1 (Φ_F = 0.34) to establish a structurally unprecedented probe. The experimental results manifested that probe XH-2 (Φ_F = 0.15) was able to detect hydrogen peroxide using a fluorescence method with an excellent linear range of 0-140 μM (R² = 0.9974) and an especially low detection limit of 91 nM (λ_ex/em = 570 nm/638 nm). In addition, the probe was capable of monitoring hydrogen peroxide in a colorimetric manner with the linear range of 0-110 μM (R² = 0.9965). Furthermore, the specificity, applicability in serum (98.6-109.1%) and indirect detection of glucose make the probe XH-2 a superior probe. Based on its low cytotoxicity, the probe was successfully applied to monitor endogenous/exogenous hydrogen peroxide and quantitatively determine the concentration level of hydrogen peroxide at a range of 0-120 μM (R² = 0.9859) in HepG2 cells. Ultimately, the probe could effectively monitor the level of hydrogen peroxide during DILI in HepG2 cells.

A Phenothiazine-HPQ Based Fluorescent Probe with a Large Stokes Shift for Sensing Biothiols in Living Systems

Due to the redox properties closely related to numerous physiological and pathological processes, biothiols, including cysteine (Cys), homocysteine (Hcy) and glutathione (GSH), have received considerable attention in biological science. On account of the important physiological roles of these biothiols, it is of profound significance to develop sensitive and selective detection of biothiols to understand their biological profiles. In this work, we reported an efficient fluorescent probe, PHPQ-SH, for detecting biothiols in vitro and vivo, based on the phenothiazine-HPQ skeleton, with DNBS (2,4-dinitrobenzenesulfonate) as the response unit. Probe PHPQ-SH exhibited brilliant sensing performances toward thiols, including a large Stokes shift (138 nm), excellent sensitivity (for GSH, LOD = 18.3 nM), remarkable fluorescence enhancement (163-fold), low cytotoxicity, rapid response (8 min), and extraordinary selectivity. Finally, the probe PHPQ-SH illustrated herein was capable of responding and visualizing biothiols in MCF-7 cells and zebrafish.