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Abstract Fast, highly selective and sensitive thiophenol probes are highly desirable in the field of bioimaging and environmental monitoring. For that, based on the mechanism that thiophenol can effectively cleave the sulfonamide bond selectively, we herein report a dicyanoisophorone-based Red-emitting/NIR probe for thiophenol detection. This probe had some desirable properties such as rapid response, high selectivity and sensitivity, remarkable large Stokes shift (181 nm), Red-emitting/NIR fluorescence region and low LOD value (80 nM, according to 3σ/s). Moreover, this novel Red-emitting/NIR probe can potentially be applied to the detection of thiophenols in real water samples quantitatively and fluorescent imaging in living cells and zebrafishes. Graphical Abstract Unlabelled Image Highlights • Probe with dicyanoisophorone has good membrane permeability and large Stokes shift. • Ideal fluorescence intensity and red-emitting/NIR emission (650 nm) • Instantaneous response (few seconds) and intensity levelled off within 7 min. • Probe has High selectivity. • Application in real water sample and cell even in vivo(zebrafish) [ABSTRACT FROM AUTHOR]

• Detecting CYP3A5 activity using fluorescent probe for the first time. • Excellent sensitivity (LOD = 0.04581 nM) was realized in Hcy-Br. • Hcy-Br possessing Preferable mitochondria-specific targeting (Rr = 0.8746). • Visualization of living cells and tumor-bearing mice was achieved in Hcy-Br. Cytochrome P450 (CYP) 3A5 as the most important CYPs in the CYP3A isoform, is polymorphic and plays a significant role in drug metabolism. Herein, two novel enzyme-activatable near-infrared (NIR) ratiometric fluorescent probes (Hcy-Br and Hcy-Cl) are designed and synthesized to measure the activity of CYP3A5 in complex biological systems. Hcy-Br possesses excellent sensitivity in response to CYP3A5 enzyme with the LOD = 0.04903 nM and could quickly reach equilibrium within 30 min. The ability of targeting mitochondria, along with preferable Pearson's correlation coefficients (Rr) of 0.8746, is realized in Hcy-Br. The application of Hcy-Br in living cells and tumor-bearing mice is also achieved successfully for monitoring endogenous CYP3A5 activity. Detecting CYP3A5 activity in living system via fluorescent probe, to the best of our knowledge, is reported for the first time. These findings suggest that Hcy-Br could be served as a useful tool for selectively detecting the activity of endogenous CYP3A5 in vivo, providing assistance for investigating the function of CYP3A5 in drug metabolism and pathologic process. [ABSTRACT FROM AUTHOR]

Abstract A novel near-infrared fluorescent probe RHCC was devised and synthesized. It exhibits high specificity to Fe3+ compared to other metals in aqueous solutions. The detection limit of RHCC was 1.2 × 10−7 M and the complexation stability constant was 5.807 × 104 M−1. The binding ratio of RHCC and Fe3+ was 1:1 which was measured through MS, FTIR and Job's plot. The energy gap between HOMO and LUMO of RHCC was 3.22 eV, while RHCC- Fe3+ complex was 0.95 eV. This result means the binding of probe RHCC and Fe3+ lowers the RHCC- Fe3+ complex's energy gap and makes it more stable. What's more, in living cells and zebrafishes studies, probe RHCC was no significant cytotoxic effect, indicating it could monitor Fe3+ in biological system. Graphical abstract fx1 Highlights • A novel near-infrared "turn-on" fluorescent probe RHCC had been synthesized. • The probe RHCC exhibits high sensitivity and excellent selectivity to Fe3+. • The probe RHCC can be used for characteristic 'naked-eye' detection of Fe3+. • The probe RHCC can monitor Fe3+ in biological system. [ABSTRACT FROM AUTHOR]

Cytochrome P450s have brought considerable attention to researchers for their significant correlations with metabolic behaviors of procarcinogenic chemicals. To better understand the roles of CYP1A in biological and physiological systems, we developed a novel ratiometric fluorescence probe N-((2-hydroxyl ethoxy) ethyl)− 4-methoxy-1, 8-naphthalimide ( NEMN ) allowing for selectively and sensitively monitoring the target enzymes under physiological conditions and living cells. The probe was designed based on substrate predilection of CYP1A and its outstanding O-dealkylation capacity, and 1, 8-naphthalimide was chosen as fluorophore on account of its desirable photophysical properties. Absorption and emission spectra of the probe solution and reacted metabolism showed obvious red-shift with remarkable colour changes, which indicated that NEMN could be a promising ratiometric detector of CYP1A. Additionally, the selectivity assays displayed that NEMN only sensitive to CYP1A1 and CYP1A2 enzymes with scarce interference of other CYPs. Furthermore, the excellent linear relationships between the ratio of fluorescent intensities and incubation time and enzymes concentration signified time- and concentration- dependence of the probe, which were of desire benefit to quantify and monitor the CYP1A-involved biological behaviors in physiological conditions. The assay in real living samples (Human liver microsomes) further proved the analytical utility of the probe. Finally, the cytotoxicity assay and confocal fluorescence imaging demonstrated that this probe was of great promise for detecting the activity of endogenous CYP1A in human living cells. [ABSTRACT FROM AUTHOR]

Reactive sulfur species (RSS), primarily containing glutathione (GSH), cysteine (Cys), hydrogen sulfide (H 2 S) and hydrogen polysulfides (H 2 S n , n > 1), were crucial endogenous biological signal molecules. Among them, H 2 S and H 2 S n played extremely momentous roles in many physiological and pathological processes. Limited by the vivo environmental diversity and complexity, it was highly desirable to rely on the single fluorescence probe platform to visualize H 2 S n and H 2 S according different fluorescence signals. Herein, we reported a two-photon excited fluorescent probe MC-S n that had the following merits: (Ⅰ) ratiometric and colorimetric: reducing detection errors and conducting visual analysis; (Ⅱ) two-photon microscope: better performance in vivo and vitro imaging; (Ⅲ) two specific sulfide reaction sites: studying on the mutual transformation of H 2 S n and H 2 S in biological systems. Furthermore, take advantages of low cytotoxicity (cell viability ≥ 85.99%), low limit of detection (21 nM), significant photostability, excellent pH stability, quick response behavior (175 s) and high penetration depth (110 μm), MC-S n can be employed to visualize endogenous and exogenous H 2 S n and H 2 S in cells, liver tissues and zebrafish. • Ratiometric and colorimetric: reducing detection errors and conducting visual analysis. • Two-photon microscope: better performance in vivo and vitro imaging. • Two specific sulfide reaction sites: studying on the mutual transformation of H2Sn and H2S in biological systems. • Low limit of detection (21 nM) and high penetration depth (110 μm). [ABSTRACT FROM AUTHOR]