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Hydrazine (N2H4) is a highly toxic and harmful chemical reagent. Fluorescent probes are simple and efficient tools for sensitive monitoring of N2H4 enrichment in the environment, humans, animals, and plants. In this work, a ratiometric fluorescent probe (FP‐1) containing coumarin was used for hydrazine detection. The proposed FP‐1 probe had a linear detection range of 0–250 μM and a limit of detection (LOD) of 0.059 μM (1.89 ppb). A large red Stokes shift was observed in fluorescence and UV–vis absorption spectra due to the hydrolysis of ester bonds between FP‐1 and hydrazine. The hydrazine detection mechanism of FP‐1 was also investigated using density functional theory (DFT) calculations. Finally, FP‐1 could sensitively and selectively monitor hydrazine in actual water samples and BEAS‐2B cells. Therefore, it has great application potential in environmental monitoring and disease diagnosis. [ABSTRACT FROM AUTHOR]

Strongly blue fluorescent N-doped carbon dots (CDs) were synthesized by using citric acid (CA) as the carbon source and diethylenetriamine (DETA) as the nitrogen source using a one-step hydrothermal method. Several synthetic parameters, including the molar ratios of initial starting materials, the temperature and time of hydrothermal reaction, were investigated and optimized. The range and average value of the diameters of the resultant CDs were 1.2-4.0 nm and 2.3 nm, respectively. The synthesized CDs display fluorescence with excitation/emission maxima of 391/438 nm and a quantum yield of 58%. Fluorescence is quenched by Co(II) ions, and this effect was exploited to design a method for determination of Co(II) in water and to image it in living HeLa (cervical carcinoma) cells. The limit of detection and linear range of Co using the synthesized CDs as fluorescence probe are 0.4 μmol·L and 0-90 μmol·L, respectively. Due to the selective and sensitive response of Co, the CDs possess potential applications in biological labeling for the demands such as monitoring the distribution of vitamin B-12 or other cobalt-containing medicines in cells or organisms . [ABSTRACT FROM AUTHOR]

Based on fluorescein, a novel water-soluble and reversible fluorescent probe (Flu-Py) was designed and synthesized for the sequentially “ON–OFF–ON” fluorescent detection of Al 3+ and F − in concentration range of 0–10 μmol L −1 and 0–30 μmol L −1 , respectively, with high sensitivity and excellent selectivity. The detection limits for Al 3+ and F − were 0.092 μmol L −1 and 0.112 μmol L −1 , respectively. The binding mode and sensing mechanism of Flu-Py with Al 3+ was verified by density functional theory (DFT) and time dependent density functional theory (TDDFT) calculation. The “ON-OFF–ON” fluorescent property of Flu-Py upon the addition of Al 3+ and F − was utilized for the imaging of living cells. [ABSTRACT FROM AUTHOR]

In this article, a novel fluorescent probe (NRBE) for detecting H 2 O 2 was developed using benzyl boronic ester as the H 2 O 2 -recognized group and Nile red as the matrix. The probe has several advantages, such as good selectivity, high sensitivity (LOD = 75 nM), good water solubility and emission in the near-infrared region (ex/em:585/670 nm). With the NRBE probe, the endogenous H 2 O 2 in human hepatocellular carcinoma cells BEL-7402, was detected, and the H 2 O 2 generated during the ischemia-reperfusion of the cells was imaged. These results show that NRBE can be applied for real-time detection of H 2 O 2 in biological systems. Unlabelled Image • A novel Nile red-based fluorescent probe NRBE was designed and synthesized for H 2 O 2 detection. • The probe has good selectivity, high sensitivity, good water solubility and emission in the near-infrared region. • The probe can be applied for real-time detection of H 2 O 2 in biological systems. [ABSTRACT FROM AUTHOR]

A water-soluble fluorescence probe (TF) derived from fluorescein has been developed. This probe can be used to detect ClO − and Cd 2+ under physiological condition based on oxidation and coordination reactions, exhibiting almost 64-fold and 4-fold fluorescence enhancement. The experimentally observed changes in the structure and electronic properties of the probe in the presence of ClO − and Cd 2+ were modeled by density functional theory (DFT) and time-dependent density functional theory (TDDFT) computational calculations. Moreover, the present probe was successfully applied to the fluorescence imaging of ClO − and Cd 2+ in living cells. [ABSTRACT FROM AUTHOR]

In this work, a novel phenoxazine-based fluorescent probe BPO - N 3 was developed to detect H 2 S. The results showed that the probe had high selectivity and sensitivity toward H 2 S, and its detection mechanism was based the ratio between green and red fluorescence signals; its detection limit was as low as 30 nM. The fluorescent imaging experiments further showed that the probe BPO - N 3 could successfully detect endogenous and exogenous H 2 S in living cells. This probe can be used as a powerful tool for in-depth study of H 2 S function in various physiological processes. Unlabelled Image • A novel phenoxazine-based fluorescent probe BPO-N 3 was developed to detect H 2 S. • Linear response (0.1 to 20 μM), high selectivity and sensitivity (LOD = 30 nM) were observed. • The probe BPO-N 3 could successfully detect endogenous and exogenous H 2 S in living cells. [ABSTRACT FROM AUTHOR]

Herein we report a new carbazole-benzo[e]indolium dye (CEBI) as a ratiometric fluorescent and chromogenic probe for sulfite (SO 3 2− ) detection based on intramolecular charge transfer (ICT) mechanism. Upon treatment with SO 3 2− , the probe CEBI displayed a remarkable fluorescence ratiometric response (∼560-fold fluorescenc enhancement) together with a color change from red to weak red and a large shift (135 nm) in emission wavelength. The experimentally observed changes in the spectral features of the probe upon addition of SO 3 2− were systematically studied using high resolution electrospray ionization mass spectrometry (HR-ESI–MS), proton nuclear magnetic resonance ( 1 H NMR), and time-dependent density functional theory (TDDFT) calculations. We found a linear relationship between the ratio of fluorescence intensities at 465 nm and 600 nm ( F 465 /F 600 ) and SO 3 2− concentration over the range of 0–40 μM with a detection limit of 0.025 μM. Moreover, the novel probe demonstrated fluorescence imaging of SO 3 2− in living cells and zebrafish, suggesting its potential in clinical diagnostics. [ABSTRACT FROM AUTHOR]

Herein, we report a novel Schiff base “turn-on” fluorescent and chromogenic probe N′-(3-(benzo[d]thiazol-2-yl)-2-hydroxybenzylidene)-4-(dimethylamino)-benzohydrazide (BHDB) for CN − detection under physiological pH, based on nucleophilic reaction of imine ( CH N ) and CN − , exhibiting almost 66-fold fluorescence increase and a remarkable color change from colorless to yellow. The experimentally observed changes in the spectral properties of the probe upon addition of CN − were systematically studied using high resolution electrospray ionization mass spectrometry (HR-ESI-MS), proton nuclear magnetic resonance ( 1 H-NMR), and time-dependent density functional theory (TDDFT) calculations. Using the fluorescence spectra changes, we found a detection limit for CN − of 0.15 μmol L −1 , far lower than the maximum permissive level of CN − (1.9 μmol L −1 ) in drinking water recommended by World Health Organization (WHO). Moreover, the novel probe demonstrated fluorescence imaging of CN − in living cells and zebrafish, suggesting its potential in clinical diagnostics. [ABSTRACT FROM AUTHOR]