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Graphical abstract Highlights • Benzoxazole appended based probe (BS) was designed and synthesized. • BS showed good selectivity towards Zn2+ion with 'turnon' fluorescence emission. • BS-Zn2+ ensemble showed selective sensing towards PPi− ion. • BS and BS-Zn2+ ensemble could detect Zn2+ & PPi ions in live cells. Abstract A novel benzoxazole appended dipodal Schiff base (BS) was synthesized and its sensing property was investigated. The receptor BS detected Zn2+ ions selectively by turn-on fluorescence among the wide range of metal ions in DMSO-H 2 O (1:9 v/v, 50 mM HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid) at pH 7.4. The different physicochemical parameters of BS-Zn2+ complex were investigated by UV–vis, photoluminescence, 1H NMR titration and ESI-MS techniques. The limit of detection (LOD) and binding constant (K b) of BS-Zn2+ complex have been determined by fluorescence titrations and found to be 4.53 × 104 M−1 and 0.52 μM. Moreover, binding ratio of BS and Zn2+ was found to be 1:1 by Job's method. Further, the BS–Zn2+ complex was used to sense pyrophosphate (PPi) ions as a secondary sensor in HEPES buffer solution. Overall, the sensitive fluorescence behavior of the receptor BS has been utilized as a powerful tracker for zinc ion and pyrophosphate ion in biological systems. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A novel fluorescent probe for biothiols detection. • Red fluorescence with emission maxima at 640 nm and a large Stokes shift of 160 nm. • High sensitivity and selectivity. • The sensing mechanism was studied by MS and HPLC. • Endogenous biothiols imaging in living MCF-7 cells. Abstract Small molecule biothiols, including cysteine (Cys), homocysteine (Hcy) and glutathione (GSH), play important roles in physiological and pathological processes, which are related to many diseases. Hence the detection of cellular biothiols is of great significance. Here we reported a new probe DNT that was constructed by a donor-acceptor type dye NT-OH and a recognition site DNBS group. DNBS group also acted as a fluorescence quencher in this molecule. While in the presence of biothiols, the DNBS group reacted with the sulfydryl group of thiols by nucleophilic aromatic substitution reaction and then eliminated from the probe, turning on the red fluorescence of the probe with emission maxima at 640 nm and a large Stokes shift of 160 nm. Solution experiments revealed that DNT showed high sensitivity and selectivity to biothiols. Besides, it was further utilized to map endogenous biothiols in MCF-7 cells successfully. [ABSTRACT FROM AUTHOR]

A fluorescent probe ( 1 ) for distinguishing amongst biothiols, including cysteine (Cys), homocysteine (Hcy) and glutathione (GSH), is developed based on different cascade reactions. The key design feature of fluorescent probe 1 is the integration of two potential reaction groups for the thiol and amino groups of biothiols in one molecule. By reacting with the halogen atom and α, β-unsaturated malonitrile in probe 1 , Cys, Hcy and GSH can generate a total of three main products with distinct photophysical properties. Probe 1 shows a strong fluorescence turn-on response to Cys with blue–green emission by using an excitation wavelength of 390 nm. At an excitation wavelength of 500 nm, probe 1 responds to GSH over Cys and Hcy and emits strong orange fluorescence. The discrimination of biothiols can be demonstrated by cell imaging experiments, indicating that probe 1 can be a useful tool for the selective imaging of Cys and GSH in living cells. [ABSTRACT FROM AUTHOR]

A dual-site fluorescent probe based on naphthalimide and rhodamine was synthesized, which could rapidly and sensitively respond to H 2 S and Cu2+ with different fluorescence signals. [Display omitted] • The dual-responsive fluorescent probe (DTR-1) for detection of H 2 S and Cu2+ was developed. • DTR-1 could detect H 2 S and Cu2+ within 1 min. • The LOD for H 2 S and Cu2+ were calculated to be 0.035 μM and 0.16 μM, respectively. • DTR-1 was successfully applied to detect intracellular H 2 S and Cu2+. A highly selective and sensitive fluorescence probe (DTR-1) for simultaneously detecting H 2 S and Cu2+ with different fluorescence signals was synthesized. DTR-1 displayed remarkable fluorescence enhancement (560 nm, 34-fold) when H 2 S was added under excitation of 410 nm with the solution's color change from dark to green. The limit of detection (LOD) for H 2 S was calculated to be 0.035 µM. By contrast, the addition of Cu2+ enhanced obviously the emission intensity of DTR-1 with the maximal peak at 630 nm and color change from colorless to orange. LOD for Cu2+ was determined to be 0.16 µM. The sensing mechanism for H 2 S and Cu2+ in DMF/PBS (9/1, v/v, pH = 7.4) was studied by 1H NMR and ESI-MS. Furthermore, the potential application of DTR-1 in biological systems had been demonstrated through imaging of living cells. [ABSTRACT FROM AUTHOR]

• A colorimetric and fluorescent probe QLB-CF for Hydrogen polysuldes was reported. • The probe achieved the fast naked-eye detection to H 2 S n and the detection limit as low as 0.03μM. • The QLB-CF was successfully applicable to exogenous H 2 S n detection and imaging in living cells. A colorimeric and fluorescent probe QLB-CF has been developed for the highly sensitive and specific imaging of hydrogen polysuldes (H 2 S n , n> 1). Its selective fluorometric/colorimetric sensing of H 2 S n was demonstrated in detail. Upon addition of H 2 S n , the probe exhibited fast response to H 2 S n along with a remarkable color change from colorless to yellow which could be easily observed by the naked eye. Similarly, the probe exhibited fluorescence response to H 2 S n with approximately 7-fold fluorescence enhancement and the fluorescence color change from none to cyan. In addition, the probe displayed high selectivity towards H 2 S n among various analytes. What's more, the probe has been successfully applied to exogenous H 2 S n detection and imaging in living cells, allowing us to visualize its sensing potential application in living cells. [ABSTRACT FROM AUTHOR]

The development of biothiol fluorescent probes is of great significance in life sciences and clinical medicine. In the present study, a novel fluorescent probe, 2-(benzo[ d ]thiazol-2-yl)-1,4-phenylene bis(2,4-dinitrobenzenesulfonate) (BTPB), was synthesized and characterized by NMR and HRMS. BTPB can selectively detect biothiols over other analytes in a DMSO-HEPES solution, taking the advantages of low cytotoxicity, a large Stokes shift (160 nm) and a low detection limit (0.174–0.399 μM). The fluorescence response of BTPB to calf serum and the test strip provided strong evidence of the practical applicability. In addition, the probe was successfully applied in imaging of HepG2 cells and zebrafish. Unlabelled Image • An ESIPT-based fluorescent probe with dual recognition factor was synthesized. • The reaction mechanism was studied by DFT calculation, HRMS and NMR. • BTPB exhibits low toxicity, high efficiency and a large Stoke shift (160 nm). • BTPB was also successfully used in imaging HepG2 cells and zebrafish. [ABSTRACT FROM AUTHOR]