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The first difunctional probe H-1 for detecting ONOO− and Zn2+ at the same time showed high selectivity, good anti-interference capability, lower detect limit and short response time to them. [Display omitted] • · A new difuctional probe H-1 for ONOO− and Zn2+ detection at the same time was obtained firstly. • ·H-1 showed good selectivity and strong anti-interference ability for detecting ONOO− and Zn2+. • ·H-1 could fast response to ONOO− and Zn2+ in 15 s. • ·H-1 was used to monitor the ONOO− and Zn2+ level in living cells. Peroxynitrite (ONOO−) is one of the most significant reactive oxygen species (ROS) in living cells. Zn2+ in living cells plays an essential part in different physiological processes. The abnormal concentration of ONOO− and Zn2+ in living cells are related to many kinds of diseases, such as anemia, epilepsy, diarrhea, Alzheimer's disease, and so on. The relationship of ONOO− and Zn2+ in living cells when the relative disease occurs remains unknown. So we develop the first probe H-1 for detecting ONOO− and Zn2+ at the same time. The probe H-1 shows high selectivity, good anti-interference capability, low detection limit and short response time to ONOO− and Zn2+. When the probe was applied to detect ONOO− and Zn2+ in HeLa cells, we could observe the fluorescence changing in the green and blue channels separately without interference in real time. It has the potential to employ the relation of ONOO− and Zn2+ in some disease mechanism research. [ABSTRACT FROM AUTHOR]

[Display omitted] • The first coumarin-based HNO donor (CD1) was developed. • HNO-releasing has a t 1/2 ∼90 min under physiological conditions. • The fluorescence intensity increased by about 4.9-fold. • HNO release can be visualized by cellar images. Nitroxyl (HNO), the single-electron reduction product of nitric oxide (NO), has attracted great interest in the treatment of congestive heart failure in clinical trials. In this paper, we describe the first coumarin-based compound N -hydroxy-2-oxo-2H-chromene-6-sulfonamide (CD1) as a dualfunctional HNO donor, which can release both an HNO signaling molecule and a fluorescent reporter. Under physiological conditions (pH 7.4 and 37 °C), the CD1 HNO donor can readily decompose with a half-life of ∼90 min. The corresponding stoichiometry HNO from the CD1 donor was confirmed using both Vitamin B 12 and phosphine compound traps. In addition to HNO releasing, specifically, the degradation product 2-oxo-2H-chromene-6-sulfinate (CS1) was generated as a fluorescent marker during the decomposition. Therefore, the HNO amount released in situ can be accurately monitored through fluorescence generation. As compared to the CD1 donor, the fluorescence intensity increased by about 4.9-fold. The concentration limit of detection of HNO releasing was determined to be ∼0.13 μM according to the fluorescence generation of CS1 at physiological conditions. Moreover, the bioimaging of the CD1 donor was demonstrated in the cell culture of HeLa cells, where the intracellular fluorescence signals were observed, inferring the site of HNO release. Finally, we anticipate that this novel coumarin-based CD1 donor opens a new platform for exploring the biology of HNO. [ABSTRACT FROM AUTHOR]

[Display omitted] • Based on dicyanoisophorone skeleton a near-infrared fluorescent probe was prepared and used to detect CO with high selectivity. • Two emission channels ratiometric fluorescence changes can be observed through adjusting the ICT effect of probe by CO. • The design of the probe enables it to be used for detecting CO in lysosomal subcellular organelles and further validated through cell co-localization imaging experiments. • The probe can be used to detect the endogenous and exogenous CO in Hela cells and could be used in living mice. • The probe is capable of detecting endogenous and exogenous CO through cell imaging experiments and has been successfully used in living mice. Carbon monoxide (CO) as an endogenous gas signaling molecule possesses important physiological functions and is of great significance in the treatment of various diseases. Real-time tracking of CO in living organisms has become a research hotspot in recent years. This article presents a lysosomal targeted near-infrared ratio fluorescence probe (TBM-CO) for selective detection of CO based on the dicyanoisophorone skeleton and morpholine fragment. The probe TBM-CO with weak ICT effect can be transformed to precursor TBM-NH 2 with strong ICT effect by the traditional Tsuji-Trost reaction procession in the presence of Pd2+ ions. The mechanism was proved by DFT calculation or the MS and HPLC results respectively. In the near-infrared region an obvious ratio fluorescence intensity change (F 686 / F 616) is observed in vitro spectral experiments. The concentration titration experiments indicate that there is a good liner relationship between the ratio fluorescence intensity and the concentration in the range of 0 to 50 μM (R2 = 0.996) and the detection limit is calculated as 0.38 μM. The cell fluorescence imaging and co-localization experiments further demonstrate that TBM-CO is able to detect the exogenous and endogenous CO in lysosomal subcellular organelle. Finally, it was used to detect the changes of CO concentration in living mice successfully. In short, a probe with three advantages of near-infrared emission, ratiometric fluorescence and organelle targeting was reported and used to detect CO successfully in cells and in living mice. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new fluorescent probe CSH based on carbazole-thiophene was synthesized for the detection of ClO−. • CSH exhibits specific recognition of ClO− in the UV and fluorescence spectra, with detection limits as low as 3.61 × 10−6 mol/L and 1.16 × 10−6 mol/L. • Probe CSH can not only realize the detection of real water samples, but also can be applied to the detection of exogenous ClO− in HeLa cells. A carbazole thiophene-aldehyde and 4-methylbenzenesulfonhydrazide conjugate CSH was synthesized by introducing 5-thiophene aldehyde at the 3-position of the carbazole group as the precursor and then condensing it with 4-methylbenzenesulfonhydrazide. CSH has high selectivity and sensitivity towards ClO−, which can specifically identify ClO− by UV–Vis and fluorescence spectroscopy. CSH can rapidly respond to ClO− in the physiological pH range through a fluorescence quenching pattern, accompanied by the color of CSH changing markedly from turquoise to yellowish green under the 365 nm UV light. Probe CSH exhibits a quantitative response to ClO− (0–11 μM) with a low detection limit (1.16 × 10−6 M). Cell imaging experiments have shown that CSH can capture fluorescent signals in the cyan and yellow channels of HeLa cells through fluorescence confocal microscopy, and can successfully identify exogenous ClO− in HeLa cells. In addition, probe CSH can also be used to detect ClO− in environmental water samples. These results indicate that CSH has potential application prospects in the environmental analysis and biological aspects. [ABSTRACT FROM AUTHOR]

In this manuscript, we designed and synthesized a fluorescent probe HBA based on caffeic acid for detecting Al3+ and HPO 4 2− by the mode of "off-on-off". The probe HBA can be utilized as a powerful method for the sequential recognition of Al3+ and HPO 4 2– in biological samples. [Display omitted] • A new dual-functioned fluorescent probe HBA based on caffeic acid was synthesized. • The new fluorescent probe HBA can sequential detect Al3+ and HPO 4 2–− with good selectivity and excellent sensitivity. • The probe HBA has good performance for detection of Al3+/HPO 4 2– in HeLa cells. In this work, we focused on synthesizing a new fluorescent probe HBA based on caffeic acid for detecting Al3+/HPO 4 2− by the mode of "off-on-off". HBA alone exhibited a weak fluorescence emission in aqueous solution. When Al3+ was added into the HBA solution, a significant green fluorescence was found at 498 nm. However, the introduction of HPO 4 2− to the solution of [ HBA -Al3+] complex induced the disappearance of green fluorescence. The detection limit of HBA was calculated as low as 41.7 nM for Al3+ and 62.1 nM for HPO 4 2−, respectively. Probe HBA exhibited good cell-membrane penetrability and had the potential to trace Al3+/HPO 4 2− in biological systems. [ABSTRACT FROM AUTHOR]

[Display omitted] • Lysosome-targeted carbon dots (L-CDs) were synthesized from hematoxylin. • The L-CDs have been used to visually recognize Hg2+ and SO 3 2− by smartphone. • The L-CDs have been employed to differentiate Hg2+ and SO 3 2− in living cells. Smartphone-assisted visual assay not only expands quantitative analysis but also enhance real-time on-site sensing capabilities. Herein, lysosome-targeted dual-emissive carbon dots (L-CDs) can not only recognize Hg2+ and SO 3 2− by ratiometric fluorescence and ratiometric absorption, but also visually quantify Hg2+ and SO 3 2− by smartphone-assisted method. With monitoring of intrinsic ratiometric fluorescent variation (I 580 /I 468), L-CDs are developed as an effective sensing platform for ratiometric fluorescent successive identification of Hg2+ and SO 3 2− accompanying with continuous fluorescence variation of blue, purplish pink, pink, and light yellow. With detecting of inherent ratiometric absorption change (A 538 /A 206), L-CDs are also constructed as an efficacious sensing terrace for ratiometric absorption consecutive discrimination of Hg2+ and SO 3 2−. More crucially, integrating continuous fluorescence color change and color recognizer APP in the smartphone, visual quantification of Hg2+ and SO 3 2− can be accomplished on the basis of the ratio of red value and blue value (R/B) with linear ranges of 0–130 and 0–850 µM, respectively, as well as LOD of 8.4 and 12.9 nM, respectively. More interestingly, confocal fluorescent imaging of HeLa cells further verifies that L-CDs can be regarded as favorable biosensors for on-site, real-time differentiation of Hg2+ and SO 3 2− in vitro and in vivo with ratiometric manners. [ABSTRACT FROM AUTHOR]

[Display omitted] • Chemosensor was configured by attaching responsive group, diaminomaleonitrile, to BODIPY scaffold. • Cu2+ can be selectively recognized on a 2-s time-scale. • The recognition mechanism is based on the Cu2+ induced intramolecular oxidative cyclization of γ-aminoimine. • The absolute fluorescence quantum yield of BD + Cu2+ is determined to be 98%, attributing to the formation of dicarbonitrile substituted imidazole ring. A highly fluorescent Cu2+-responsive sensor, 2-amino-3-(BODIPYmethyleneamino)maleonitrile (BD) was constructed by attaching diaminomaleonitrile to a BODIPY scaffold. Cu2+ can be selectively recognized on a 2-s time-scale by way of fluorescence emission. When Cu2+ and BD coexist in solution, typical BODIPY emission was observed and the emission intensity could be increased to 334 times that of the blank dye solution. The mechanism of fluorescence increase is based on the generation of highly fluorescent species by Cu2+-triggered oxidative cyclization of the attached diaminomaleonitrile. The absolute fluorescence quantum yield (AFQY) of the cyclization product is 98% determined by integrating sphere. The highly emissive character can be attributed to the imidazole ring and dicarbonitrile on the BODIPY scaffold. It surpasses the meso -phenyl substituted analogue in AFQY and detection limits (DL). The specific Cu2+ recognition behavior was also validated in Hela cells with high-contrast fluorescence images. [ABSTRACT FROM AUTHOR]

[Display omitted] • Probe FBC-DS performed sufficient selectivity, fast response time, high sensitivity and a large Stokes shift to HClO. • FBC-DS was applied for imaging of exogenous and endogenous HClO in living HeLa cells and zebrafish with satisfactory performances. • FBC-DS was applied for corroborating that HClO could be an efficient marker for APAP-induced hepatotoxicity in the mice liver injury models. Drug-induced liver injury (DILI), as a classic acute inflammation, has attracted widespread concern due to its unpredictability and severity. Among the various reactive oxygen species, HClO has been used as a marker for the detection of DILI process. Thus, we designed and synthesized a "turn-on" fluorescent probe FBC-DS by modifying 3'-formyl-4'-hydroxy-[1,1'-biphenyl]-4-carbonitrile (FBC-OH) with N, N-dimethylthiocarbamate group for sensitively sensing HClO. Probe FBC-DS showed a low detection limit (65 nM), fast response time (30 s), an enormous Stokes shift (183 nm) and 85-fold fluorescence enhancement at 508 nm in the detection of HClO. Probe FBC-DS could monitor exogenous and endogenous HClO in living HeLa cells, HepG2 cells and zebrafish. In addition, probe FBC-DS has been successfully utilized in biological vectors for imaging acetaminophen (APAP)-induced endogenous HClO. Moreover, DILI caused by APAP is evaluated by probe FBC-DS through imaging over-expression of endogenous HClO in the mice liver injury models. All in all, we have every reason to believe that probe FBC-DS can be a potential tool to study the complex biological relationship between HClO and drug-induced liver injury. [ABSTRACT FROM AUTHOR]

A multifunctional fluorescent probe with "ESIPT+AIE" properties were synthesized. Three mental ions including Pb2+, Ag+ and Fe3+ could be selectively recognized and distinguished and remarkable fluorescence enhancement was observed. [Display omitted] • 1. A multifunctional fluorescent probe with "ESIPT + AIE" properties was synthesized. • 2. Pb2+, Ag+ and Fe3+ ions could be selectively recognized and distinguished with remarkable fluorescence enhancement. • 3. The probe had been successfully applied to water sample detection, test paper experiment and biological cell imaging. In this work, three Schiff-based fluorescent probes with aggregation-induced emission (AIE) and excited intramolecular proton transfer (ESIPT) characters were synthesized by grafting 2-aminobenzothiazole group onto 4-substituted salicylaldehydes. More important, a rare tri-responsive fluorescent probe (SN-Cl) was developed by purposeful variation of substituents in the molecule. It could selectively identify Pb2+, Ag+ and Fe3+ in different solvent systems or with the help of masking agent and show complete fluorescence enhancement without interference of other ions. Meanwhile, the other two probes (SN-ON and SN-N) could only recognize Pb2+ in DMSO/Tris-HCl buffer (3: 7, v/v, pH = 7.4). According to Job's plot, density functional theory (DFT) calculations and NMR analysis, coordination between SN-Cl and Pb2+/Ag+/Fe3+ was determined. The LOD values for three ions were as low as 0.059 μM, 0.012 μM and 8.92 μM, respectively. Ideally, SN-Cl showed satisfactory performance in real water samples detection and test paper experiments for three ions. Also, SN-Cl could be used as an excellent imaging agent for Fe3+ in HeLa cells. Therefore, SN-Cl has the ability to be a "single fluorescent probe for three targets". [ABSTRACT FROM AUTHOR]

A quinoline-based fluorescence sensor QDTD was developed for Zn2+. QDTD can detect Zn2+ by fluorescence turn-on. Detecting limit (0.27 μM) of QDTD for Zn2+ was far below WHO standard (76.0 μM). For the practical application, compound QDTD could be used to determine Zn2+ in real samples and applied to the test kit. More importantly, QDTD was expertly applied for Zn2+ imaging in HeLa cells and zebrafish with good membrane-permeability. Detection mechanism of Zn2+ ion by compound QDTD was suggested through the analytical tools like 1H NMR titration, ESI-MS, Job plot, fluorescent and UV–vis titration, and theoretical calculations, and through the synthesis and applications of a model compound AAQA. Unlabelled Image • A highly selective fluorescent chemosensor QDTD for Zn2+ was designed and synthesized. • QDTD could detect Zn2+ by fluorescence turn-on with the low detection limit (0.27 μM). • Sensor QDTD was applied to the real water samples and test strip. • Sensor QDTD could successfully quantify Zn2+ in HeLa cells and zebrafish. [ABSTRACT FROM AUTHOR]

[Display omitted] • A fluorescent probe was synthesized based on benzopyran-chromone for detection of ONOO−. • The probe shows short response time for ONOO− (<30 s). • The probe shows specifically selectivity and a very low detection limit of 22.4 nM for ONOO−. • The probe can accurately identify endogenous and exogenous ONOO− in HeLa cells. Peroxynitrite is widely present in organisms and closely related to many pathophysiological functions. Therefore, it is of great physiological significance to develop capable probes for detecting ONOO−. In this work, a novel fluorescent probe B-Ch was designed based on the intramolecular charge transfer (ICT) effect. By means of molecular engineering, the replacement from diethylamine group to hydroxyl group has improved the detection sensitivity of the probe. After the addition of ONOO−, the solution color and fluorescence showed noticeable changes, which were visible to the naked eye. The probe showed excellent advantages: visualization, good selectivity, low sensitivity (22.4 nM), good stability and biocompatibility, exogenous and endogenous imaging of ONOO− in HeLa cells. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nitrogen and bromine co-doped red fluorescence carbon dots (N,Br-CDs) with high QY were synthesized. • The multifunctional fluorescent sensors for off–on detection of Ag+ and glutathione were constructed based on N,Br-CDs. • The fluorescence sensor has been applied to the determination of Ag+ in environmental water samples. • Cellular imaging of Ag+ and glutathione was performed in HeLa cells by the N,Br-CDs. Carbon dots (CDs) with red fluorescence emission have excellent advantages in cell imaging. Herein, novel nitrogen and bromine doped CDs (N,Br-CDs) were prepared with 4-bromo-1,2-phenylenediamine as precursor. The N, Br-CDs present the optimal emission wavelength at 582 nm (λ ex = 510 nm) at pH 7.0 and 648 nm (λ ex = 580 nm) at pH 3.0 ∼ 5.0, respectively. The fluorescence intensity of N,Br-CDs at 648 nm versus Ag+ concentration shows a good relationship from 0 to 60 μM with the limit of detection (LOD) of 0.14 μM. Furthermore, the fluorescence of N,Br-CDs/Ag+ is efficiently restored via the combination of glutathione (GSH) and Ag+ and linearly changes with GSH concentration from 0 ∼ 6.0 μM with LOD of 49 nM. This method has been successfully employed to monitor intracellular Ag+ and GSH with fluorescence imaging. The results suggest that the N,Br-CDs has application potential in the sensing of Ag+ and visual monitoring of GSH in cells. [ABSTRACT FROM AUTHOR]

Hydrogen sulfide (H 2 S) is a kind of gaseous signal molecule in many physiological processes. In order to detect H 2 S, a novel "turn on" fluorescent probe 6,12-dihydroxyperylene-1,7-dione (DPD) was designed and synthesized. The probe DPD is fluorescence silence, while the addition of H 2 S induces an obvious green fluorescence with an obvious color change from dark blue to yellow-green. The probe shows excellent selectivity, fast response (2.5 min) and linear curve (0–90 μM) in wide effective pH range (4–10). Competition experiments are also revealed in corresponding studies and the detection limit is 3.6 μM. The response mechanism is proved to be the reduction of the probe by H 2 S, which is confirmed by 1H NMR. Furthermore, through the fluorescence turn-on signal toward H 2 S in Hela cells, probe DPD was successfully applied to monitor H 2 S in living Hela cells. Unlabelled Image • A "turn-on" probe DPD for hydrogen sulfide was developed. • DPD shows highly selective and sensitive response to hydrogen sulfide. • DPD shows rapid response and high sensitivity toward hydrogen sulfide. • The response mechanism of the probe DPD with H 2 S was confirmed to be reduction of carbonyl groups to hydroxyl groups. • DPD can monitor the exogenous cysteine in solution and living cells. [ABSTRACT FROM AUTHOR]

Abstract A selective diaminomaleonitrile-based fluorescent probe for Al3+(L) has been synthesized and characterized. The sensing behavior of L towards different metal ions was investigated by fluorescent spectra and competition experiment. The results showed that L exhibited a dual channel emission (λ em 522 & 558 nm) with yellow fluorescence in the presence of Al3+ over other metal ions in EtOH solution. The probe L was bound to Al3+ in a 1:2 stoichiometric manner as supported by Job's plot analysis. The binding constant was 9.55 × 108 M−2 with the detection limit of 10.3 nM. The turn-on response was attributed to the inhibition of PET and C N isomerization after binding with Al3+ while the dual emissions were due to ESIPT and ICT processes. In addition, the application of L for imaging Al3+ in living Hela cells was achieved. Graphical Abstract A selective diaminomaleonitrile-based dual channel emissive probe for Al3+(L) has been fabricated. L exhibited a dual channel emission, good selectivity and low LOD value towards Al3+. Importantly, it is suitable for fluorescence imaging in living Hela cells. Unlabelled Image Highlights • A new diaminomaleonitrile-based fluorescent probe for Al3+(L) has been synthesized and characterized. • L has a dual channel emission with yellow fluorescence in the presence of Al3+ in EtOH solution. • The limit of detection of L for Al3+ was estimated to be as low as 10.3 nM. • L was applied in Hela cells to detect intracellular Al3+ successfully. [ABSTRACT FROM AUTHOR]

[Display omitted] • A facile receptor PBTA [2E,2′E)-3,3′-(10-octyl-10 H -phenothiazine-3,7-diyl)bis(2-(benzo[d]thiazol-2-yl)acrylonitrile] was successfully designed which shows fast response towards CN− with an excellent absorbance and emission properties. • The receptor PBTA detects CN− based on nucleophilic addition mechanism with lowest LOD and LOQ. • The receptor PBTA monitors CN− with suitable physiological pH (4–11) and also shows specific selectivity even in presence of other competitive ions. • The receptor PBTA was utilized to detect CN− present in the water samples, cyanogenic food plants and in live HeLa cells. A simple D − A (donor − acceptor) type receptor ((2 E , 2′ E)-3, 3′-(10-octyl-10 H -phenothiazine-3,7-diyl) bis (2-(benzo[d]thiazol-2-yl)acrylonitrile)) (PBTA) containing nitrile-vinyl linkage was designed and completely characterized. The receptor PBTA detects CN− ions based on "turn-off" effect with admirable spectral properties. It also owns some of the merits like "naked-eye" color change, ultrafast response (90 s), lowest detection limit (1.25 × 10-10 M) as well as quantitation limit (4.17 × 10-10 M) with the pH range 4–11 which is more suitable pH to make use of the receptor PBTA in physiological medium. The instant detecting ability of the receptor over CN− ions was proved using paper test strip and cotton balls. Further, the utilization of the receptor PBTA was also extended to track CN− ions in realistic samples (water and food samples) and in HeLa cells bioimaging. [ABSTRACT FROM AUTHOR]

A reversible Schiff's base fluorescence probe for Al 3+ , (3,5-dichloro-2- hydroxybenzylidene) quinoline-2-carbohydrazide ( QC ), based on quinoline derivative has been designed, synthesized and evaluated. The QC exhibited a high sensitivity and selectivity toward Al 3+ in EtOH-H 2 O (v/v = 1:9, pH = 6) by forming a 1:1 complex with Al 3+ and the detection limit of QC for Al 3+ was as low as 0.012 μM. Furthermore, these results displayed that the binding of QC Al 3+ was broken by F − , so this system could be used to monitor F − in the future. The enhancement fluorescence of the QC could be attributed to the inhibition of PET and ESIPT and the emergency of CHEF process induced by Al 3+ . More importantly, QC was not only successfully used for the determination of trace Al 3+ in the tap water and the human blood serum, but was valid for fluorescence imaging of Al 3+ in the Hela cells. [ABSTRACT FROM AUTHOR]

A dual-site multifunctional fluorescent probe for selective detection of endogenous H 2 O 2 and SO 2 derivatives based on ICT process and its bioimaging application. [Display omitted] • A dual-site multifunctional probe was designed for detection of endogenous H 2 O 2 and SO 3 2−. • The sensing mechanism was confirmed by 1H NMR and theoretical calculation data. • The probe was successfully used for bioimaging of endogenous H 2 O 2 and SO 3 2−. In this paper, we reported a coumarin-based fluorescent probe for selective detection of H 2 O 2 /SO 2 derivatives via ICT process. To the best of our knowledge, it was few reported with the same probe to enable visual detection of H 2 O 2 /SO 2 derivatives in vivo and in vitro. H 2 O 2 and SO 3 2− were selectively sensed over other analytes, and the probe displayed 20-fold and 220-fold relative fluorescence intensity respectively, as well as the good linear relationship and the excellent detection limits of 2.7 * 103 nM and 19.3 nM. Furthermore, the probe was successfully used for fluorescence imaging of the HeLa cells and the mice to monitor exogenous and endogenous H 2 O 2 and SO 3 2−, suggesting its potential biomedical application for investigation and detection the intermediate indicator of oxidative stress in vitro and in vivo. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel rhodamine B-based chemosensor has been developed for Cu(II) detection. • The chemosensor produces pronounced naked-eye and fluorescence responses. • The chemosensor has a high absolute fluorescence quantum yield of 77% • The chemosensor is selective for Cu(II) ions in complex matrices. • The chemosensor is suitable for fluorescence imaging in living cells. The regulation of copper in the human body is important for the prevention of several diseases. Therefore, a rhodamine B-based chemosensor 1 that demonstrates substantial affinity and selectivity was synthesized for the fluorescence imaging of copper(II). In the presence of Cu2+, the chemosensor underwent a color change from colorless to amaranth that was visible to the naked eye, and the fluorescence intensity did not change when excess EDTA was added to the solution. Furthermore, strong fluorescence was observed at 575 nm. The limit of detection was determined as 12.1 nM. The absolute fluorescence quantum yield was as high as 77 % and the stoichiometry between 1 and Cu2+ was determined to be 1:1 using a job plot. An analytical method was developed and successfully used to evaluate the sensor's ability for the fluorescence imaging of Cu2+ in HeLa tumor cells. [ABSTRACT FROM AUTHOR]

Scheme 1 The luminescence mechanism of the red-emitting CDs and R-CDs as a highly efficient "on–off" fluorescent probe for the detection of Cr 2 O 7 2- and imaging in the living-cells. [Display omitted] • N/S-doped red emitting carbon dots (R-CDs) were prepared by a convenient one-step solvothermal method using o-PDA and p-ABSA as precursors. • These R-CDs could be used for the selective and sensitive detection of Cr 2 O 7 2- with excellent detection limit (80 nM). • The R-CDs possessed low cytotoxicity and had been successfully applied to cell imaging. Cr(VI) as a toxic heavy metal ion can easily enter into the body through drinking or eating and cause liver and kidney diseases as well as cancer. Considering its high biological toxicity and adverse effects on human body, it is desirable to develop a probe to monitor its level in the environment. Herein, a high-efficiency fluorescent nanoprobe based on red emissive carbon dots (R-CDs) was established through a convenient solvothermal strategy. The as-prepared CDs with excitation-independency had the fixed emission wavelength at 627 nm when the excitation wavelength was 560 nm. Further study manifested that the new surface state formed by nitrogen and sulfur doping and the increased conjugated system established through dehydration and carbonization were the main reasons for the fluorescence redshift. In this system, these R-CDs as a fluorescent probe exhibited high specificity and sensitivity to Cr 2 O 7 2- with the linear range of 4–40 μΜ and the limit of detection could reach 80.00 nM. The quenching of these CDs by Cr 2 O 7 2- was efficiently induced through a static quenching process. Meanwhile, the obtained CDs could enter into HeLa cells through endocytosis and exhibit bright red fluorescence in cells under a confocal laser scanning microscope. Thus, this work provided a promising probe not only for detecting Cr(VI) in natural environment but also for imaging in cells. [ABSTRACT FROM AUTHOR]

Three fluorescent probes (NAP-a , NAP-b and NAP-c) of oxime compounds were synthesized for specific labeling of lipid droplets, which have the advantages of low background and high photostability. [Display omitted] • 1,8-naphthalimide fluorescent probes NAP-a NAP-b and NAP-c were used for LDs imaging. • Oxime fluorescent probe was successfully used to label LDs. • The probes were successfully used for lipid droplet imaging in cells and zebrafish. • This work achieved the first specific labeling of lipid droplets with oxime compounds. Fluorescent probes can facilitate our further comprehension of the functional and physiological roles of LDs and thus promote the development of effective therapeutic approaches. Oxime compounds are widely used due to their good crystallinity and high reactivity. However, the majority oximes fluorescent probes are usually employed for the detection of HCIO, and the application of oximes in fluorescently labeled LD S is poorly reported. In this paper, three kinds of LDs fluorescent probes (NAP-a , NAP-b and NAP-c) with D-π-A structure were synthesized by simple synthesis method with 1,8-naphthalimide as fluorescent matrix and oxime group as electron donor. These probes were highly sensitive to polarity, and possessed good photostability and low cytotoxicity. Co-staining experiments showed that these probes could target LDs and the fluorescence image was green. These probes NAP-a , NAP-b and NAP-c possessed high Pearson coefficient (HeLa cells: 0.91, 0.95, 0.86) and Manders coefficient (HeLa cells: 0.91, 0.96, 0.86) with Nile Red. Interestingly, the dynamic variations in their size, shape and distribution could be clearly observed in the oleic acid-treated cell model of LDs. Imaging of zebrafish was performed and green fluorescence was collected in zebrafish. These excellent properties make oxime compound fluorescent probes a promising fluorescent probes for studying LDs and metabolic diseases. This study opens up a new way for the preparation of LDs fluorescent probe. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel "ESIPT + AIE" based benzothiazole derivative was fabricated. • It showed strong red emission (606 nm) in high water content media with 213 nm Stokes shift. • It can selectively sense HClO with rapid response (12 s) and high sensitivity. • It can visualize the endogenous and exogenous HClO in living cells. A new "ESIPT + AIE" based dye of benzothiazole with red emission and a large Stokes shift was constructed by combining 2-(2′-hydroxyphenyl)benzothiazole as the ESIPT unit and α -cyanostilbene as the AIE unit. The compound BACN was found to be a ideal HClO chemosensor, and presented palpable fluorescence and colorimetric responses toward HClO via the HClO-trigged oxidation cleavage of the ethylene bridge activated by the electron withdrawing cyano group. BACN was capable of recognizing HClO rapidly (12 s) and sensitively under physiological conditions, with good selectivity over other biologically pertinent substances. Thanks to strong red emission (λ em = 606 nm) and large Stokes shift (213 nm) resulted from the combination of ESIPT and AIE effects, it was successfully utilized for the recognition of exogenous and endogenous HClO in living HeLa cells. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel fluorescent probe, COZ-DNB , for sensitive detection of H 2 S was developed. • Probe COZ-DNB performed sufficient selectivity, rapid detection, high sensitivity and a large Stokes to H 2 S. • COZ-DNB was applied for imaging of exogenous and endogenous H 2 S in living HeLa cells and zebrafish with satisfactory performances. Recent medical studies have confirmed that endogenous H 2 S serves as the third gas-messenger besides nitric oxide (NO) and carbon monoxide (CO), which is produced by enzyme-catalyzed metabolism of cysteine and takes part in multiple physiological processes. The abnormal levels induced by H 2 S overproduction in mammals can destroy tissues and organ systems, which lead to certain serious diseases, such as neurodegenerative diseases, cardiovascular diseases, and various cancers. In this work, we developed a novel coumarin-carbazole fluorescent probe COZ-DNB with yellow emission and a large Stokes shift for H 2 S detection. In probe COZ-DNB , the newly dye COZ-OH as a luminophore and the 2,4-dinitrophenyl ether moiety was chosen as a trigger group for H 2 S. Probe COZ-DNB itself displayed nearly non-fluorescent. However, COZ-DNB gave the remarkable fluorescence with an 83-fold enhancement in the yellow region after interaction with H 2 S. The sensing mechanism of COZ-DNB toward H 2 S was checked by means of UHPLC, HRMS and DFT/TD-DFT calculations. What's more, probe COZ-DNB also exhibited fast response (2.0 min), high sensitivity (65.0 nM), a large Stokes shift (161.0 nm), high stability and excellent selectivity. Furthermore, COZ-DNB was applied for imaging of exogenous and endogenous H 2 S in living HeLa cells and zebrafish with satisfactory performances. We anticipate COZ-DNB would be served as a potential tool for investigating the biological functions of H 2 S in pathological processes. [ABSTRACT FROM AUTHOR]

[Display omitted] • A simple flavone-based chemosensor was synthesized based on ESIPT process for ratiometric detection of hydrogen polysulfides. • The probe displayed high selective and sensitive for hydrogen polysulfides (detection limit is 0.63 μM). • The probe was successfully applied to exogenous H 2 S n detection and imaging by dual emission channels in living Hela cells. Hydrogen polysulfides (H 2 S n) as an important member of reactive sulfur species is closely relevant to many physiological functions in redox homeostasis and metabolism. Dual-channel monitor the changes of H 2 S n level in vivo is highly desired. Herein we design a simple ratiometric fluorescent probe based on flavone skeleton for highly selective detection of H 2 S n. The probe HF-NA-MC bearing 2-fluoro-5-nitrobenzoic acid group inhibited the intramolecular ESIPT process, which show the blue fluorescence of adjacent naphthalene unit. In the presence of H 2 S n , the enol form of probe is converted to conjugated keto form, resulted in a 90 nm red-shift of fluorescence emission from 450 nm to 540 nm. The ratiometric intensity (I 540 /I 450) of the probe exhibits a good linear relationship toward H 2 S n in the range of 0–120 μM, and the detection limit is estimated to be 0.63 μM. The ratiometric fluorescent probe shows high specificity and anti-interference ability for H 2 S n over other related reactive sulfur species. The probe HF-NA-MC shows promising outlook and could be applied to the confocal imaging of H 2 S n by dual emission channels in Hela cells. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel developed fluorescent probe was synthesized for subsequen detection of Al3+and PPi. • The fluorescent sensing properties can be achieved in almost 100% aqueous medium. • The detection limits of the probe 1 for Al3+ and PPi were 35.7 and 76.0 nM, respectively. • Probe 1 was successfully applied to the detection of Al3+ and PPi in lysosomes of HeLa cells. A simple hydrazone probe (1) was designed and synthesized for the successive detection of Al3+ and pyrophosphate (PPi) in almost 100% buffer environment. The probe provided O 2 N donor set for chelation with Al3+, leading to a distinct fluorescence boost at 510 nm. The in-situ formed 1 -Al3+ complex detected PPi with an "on-off" behavior. The detection limits for Al3+ and PPi were 35.7 nM and 76 nM, respectively. Benefiting from the existence of morpholine as lysosome-targeting group, probe 1 was successfully applied to the detection of Al3+ and PPi in lysosomes. [ABSTRACT FROM AUTHOR]

Giving the fact that mercury ions (Hg2+) is highly toxic, migratory and bioaccumulative and even very small quantities of mercury can cause serious damage to health problems, resulting in many diseases, such as abdominal pain, renal failure, nervous system damage. The content of mercury in drinking water quality standard of our country has been strictly limited, and the maximum allowable concentration should not exceed 0.001 mg/L. (EPA) of the United States Environmental Protection Agency defines the maximum allowable limit of inorganic mercury in drinking water as 10 nM. In this study, a novel fluorescent probe based on isophoronitriles scaffold, DNC-Hg , was designed and synthesized for monitoring mercury ion in living HeLa cells. The probe exhibited good selectivity and stability, large Stokes shift(174 nm) and low cytotoxicity. Furthermore, this stable probe DNC-Hg could be used for cellular imaging. [Display omitted] • A novel and stable fluorescent probe based on isophoronitriles scaffold was designed and synthesized for monitoring mercury ion. • The probe exhibited good selectivity and stability, large Stokes shift (174 nm) and low cytotoxicity. • The stable probe DNC-Hg could be used for cell imaging. Giving the fact that mercury ions (Hg2+) is highly toxic, migratory and bioaccumulative and even very small amounts of mercury can cause serious damage to health, resulting in many diseases, such as abdominal pain, renal failure, nervous system damage. The content of mercury in drinking water quality standard of our country has been strictly limited. Therefore, it is of good research interest to develop a stable fluorescent probe capable of detecting the presence of mercury in biological cells. In this study, a novel fluorescent probe based on isophoronitriles scaffold, DNC-Hg , was designed and synthesized for monitoring mercury ion in living HeLa cells. The good properties of the probe may be attributed to the unique strong electron-absorbing group in the structural design, the good conjugation effect, and the mature Hg2+ recognition site. The probe exhibited good selectivity and stability, large Stokes shift(174 nm) and low cytotoxicity. Furthermore, this stable probe DNC-Hg could be used for cellular imaging. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel colorimetric and fluorescent chemosensor based on diaminopyrimidine (DAPCS) was designed and synthesized. • DAPCS was applied for the highly selective and ultra-sensitive detection of Cu2+ ion in aqueous media and living cell. • The probe DAPCS for Cu2+ showed a linear correlation, and LOD was calculated as 0.014 µM. • DAPCS-based test strips were fabricated and applied to the detection of Cu2+ ions in solutions. In this paper, a new and effective diaminopyrimidine-based chemosensor (DAPCS) was developed for the highly selective and ultra-sensitive detection of Cu2+ ion in aqueous media and living cell. Characterization and structure determining of DAPCS was determined by UV–Vis, FTIR and NMR analyses. It is observed that DAPCS and Cu (II) forms a ligand to metal charge transfer (LMCT) complex which produces distinguishable red color. The results also indicate that the DAPCS easily interacts with Cu2+ ion to form a 1:1 stoichiometry complex (DAPCS -Cu2+), resulting in a bathochromic shift in absorption maximum (429 nm to 449 nm) and remarkable quenching fluorescence intensity at the wavelength of 501 nm in DMSO-H 2 O solution. Furthermore, the detection limit of DAPCS towards Cu2+ was calculated to be 3.19 µM. Meanwhile, DAPCS was applied as fluorescent probe for detection of Cu2+ ions with the detection limit of 0.014 µM. The optimal pH range of probe DAPCS for quantitative analysis of Cu2+ ions was 9–11, which renders it suitable for detection of Cu2+ under physiological conditions. Additionally, the DAPCS could be applied to detect Cu2+ in real water samples and in HeLa cells, indicating the practical uses of DAPCS in real analyses. [ABSTRACT FROM AUTHOR]

[Display omitted] • DpIn and NaIn were synthesized involving of indolium units with aryldiol moiety. • DpIn, a lysosome-targeting probe, showed strong NIR emission in viscous solutions. • NaIn was an ideal lysosome-targeting & viscous-sensitivity probe in living cells. Two novel fluorescence molecular rotors DpIn and NaIn were designed and synthesized involving of indolium units linked with meta -diphenol or ortha -naphthalenediol moiety, respectively. They underwent intramolecular charge transfer to form a cyanine-like modular system at a physiological pH. In glycerol aqueous solutions, the probe DpIn exhibited NIR strong emission (3-fold) at ca. 700 nm, while the probe NaIn displayed a turn-on emission (8-fold) with a larger Stokes shift (⊿λ ≈ 97 nm). The HeLa cell imaging experiments indicated probe DpIn and NaIn both exhibited excellent selectivity for staining intracellular lysosomes instead of mitochondria. 1H NMR spectra revealed that more electrons were accumulated around benzene ring of indolium groups, which could be the evidence for its basic character leading to the lysosomes targeted staining. Furthermore, the probe NaIn proved to be an ideal lysosome-targeting tracer for monitor the changes of viscosity caused by stimuli in living cells. [ABSTRACT FROM AUTHOR]

[Display omitted] • A simple Schiff-based sensor of far-red fluorescent AIRE for Zn2+ was synthesized. • The resultant Zn2+ complex showed good reversibility when adding PPi in an almost aqueous media. • The sensor could be utilized to detect exogenous Zn2+ and PPi in HeLa cells. A simple Schiff-base fluorescent chemosensor (1) was synthesized by the reaction of 3-amino-pyrazine-2-carbohydrazide and 7-diethylamino-3-formylcoumarin; the sensor 1 displayed a notable green emission at 524 nm in DMSO and an aggregation-induced ratiometric emission (AIRE) at 555 nm in an almost buffered aqueous media (0.5% DMSO content). The AIRE of 1 was quenched following binding to Zn2+ ions, while the fluorescence emission in the far-red region was evidently enhanced at 628 nm. Notably, the ratiometric signal output could be utilized to specifically distinguish Zn2+ among various metal ions. Moreover, the 1 -Zn2+ complex was effectively employed as a fluorescent ratiometric chemosensor for pyrophosphate (PPi) detection. The detection limit was 3.52 μM and 2.45 μM for Zn2+ and PPi, respectively. The binding mechanism was evaluated by 1H NMR, ESI-MS, single-crystal X-ray diffraction, TEM, time-resolved fluorescence spectrophotometry, and density functional theory studies. Overall, owing to its sensitive fluorescence behavior, cell imaging studies demonstrated that this sensor is capable of sensing Zn2+ and PPi in living cells. [ABSTRACT FROM AUTHOR]

[Display omitted] • A series of novel BODIPY- o , m , p -phenylenediamine-based probes. • Responsiveness under different pH conditions. • Further acidic cell imaging results showed that under acidic conditions made of formic acid or acetic acid. • Especially, the compounds have unique fluorescence in acidic environment. In this paper, a series of novel phenylenediamine-fluoroboron pyrrole fluorescent derivatives were prepared which have distinct responsiveness under different hydrogen ion concentration (pH) conditions. It is noticed that the products showed excellent fluorescence properties in different solvents, especially in tetrahydrofuran and dichloromethane, with the most prominent fluorescence intensity, while the fluorescence in methanol, acetonitrile, and dimethyl sulfoxide was weaker. Responsiveness under different hydrogen ion concentration conditions in aqueous solutions were also observed, where the fluorescence intensity is quenching when the pH is 4.0. With regard to cells imaging investigation, the products showed the prominent fluorescence in HeLa cells. Further acidic cell imaging results showed that under acidic conditions made of formic acid or acetic acid, the intracellular fluorescence of the compounds was clustered around the cells and intensive enough different from without acidity control group. Especially, the compounds have unique fluorescence in acidic environment and has great potential and research value as acidic probes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fluorescent probe VA for the detection of esterase in living cells was synthesized. • Probe VA has good biocompatibility and high resolution. • Probe VA can judge the unhealthy state of H 2 O 2 -induced living cells. Esterase activity is often used as an index to evaluate the health status of cells and plays an important role in cell metabolism and apoptosis. Herein, we develop two fluorescent probes for visual biosensing of esterase activity and imaging in living cells. In vitro, after the introduction of esterase, enzymolysis destroys the ester bond of the probe, causing the fluorescent color of probe changes from yellow to red, thus realizing the visual strategy for determination of esterase activity, with high sensitivity and selectivity. Especially, probe VA, 2-(4-acetoxystyryl)-3-ethyl-1,1-dimethyl- 1H-benzo[e]indol-3-ium, exhibits higher sensitivity with a lower detection limit (up to 7.15 × 10-6 U/mL). In the cell experiment, the fluorescent probe VA also shows good biocompatibility and high spatial resolution, and is successfully applied to the intracellular fluorescent imaging and biosensing of esterase in living cells. More importantly, the probe VA can judge the unhealthy state of H 2 O 2 -induced HeLa cells using dual-fluorescence signals. The results confirm that the fluorescence method is a reliable tool for detecting endogenous esterase in living biological system. [ABSTRACT FROM AUTHOR]

A fluoran-phenothiazine hybrid fluorescent probe for selective sensing of Fe3+ and ClO− has been rationally designed and prepared with application in fluorescence imaging. [Display omitted] • A fluoran-phenothiazine hybrid fluorescent probe FP has been designed and prepared. • FP shows high selectivity and sensitivity towards Fe3+ and ClO− by dual emission. • The low cytotoxicity allows FP to trace intracellular Fe3+ by cell imaging. Bifunctional fluorescent probes with dual-emission response attract extensive attention. A novel fluorescent probe FP , a hybrid of fluoran and phenothiazine, has been designed and synthesized for selective sensing of Fe3+ and ClO− with dual-emission changes, which involes mechanisms of Fe3+-promoted spirolactone ring opening and ClO−-induced oxidation of phenothiazine moiety, respectively. In addition, the detection limits for Fe3+ and ClO− were estimated to be 49.1 and 35.9 nM, respectively. Significantly, FP can be employed as an tracer for the detection of Fe3+ ions within living HeLa cells by fluorescence imaging. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel probe TzAr-N for LDs cell imaging was developed bases on 1,3,5-triazine. • The probe exhibited large Stokes shift (almost 80 nm) and good LDs targeting ability. • The probe could not affected by wide range of pH values. • The bio-probe TzAr-N could also marking LDs distribution in living HeLa cells. Lipid droplets (LDs) including triacylglycerols and cholesteryl esters are applied for protein transformation and protein maturation in living bodies, which have an important effect on lipid metabolism, homeostasis, and interactions with other organelles. The imbalance of LDs could lead to many serious diseases including insulin resistance, cancer, obesity, liver disease, cardiovascular disease, and neurodegenerative disease. The diameter distribution of LDs is quite extensive from 100 nm to 100 µm. Herein, we designed and constructed a novel organic bio-probe TzAr-N for LDs cell imaging with much more hydrophobic and viscous environment compared to cytosol by using 1,3,5-triazine as electron acceptor. This sensitive probe exhibited favorable merits including large Stokes shift (almost 80 nm), good LDs targeting ability, and a low biological toxicity, which also could not be affected by wide range of pH values. Furthermore, the bio-probe TzAr-N could also mark LDs distribution in living HeLa cells. [ABSTRACT FROM AUTHOR]

A series of coordinatively saturated and thermodynamically stable [Ln(dtntp)(H 2 O)] (1 – 5) bioprobes were synthesized utilizing strategically designed novel DTPA-bisamide ph-tpy (dtntp) ligand, to satisfy and modulate the dual functional prerequisites as cellular imaging and phototherapeutic agents. [Display omitted] • A series of [Ln(dtntp)(H 2 O)] (1 – 5) complexes were synthesized as cell imaging and phototherapeutic agents. • The pendant phenyl-terpyridine (Ph-tpy) moieties act as photo-sensitizing antennae to impart the desirable optical properties. • The luminescence of Eu(III) and Tb(III) used for fluorescence imaging studies. • Eu(III) and Tb(III) complexes show photocytotoxicity in HeLa cells at 365 nm. We report here a series of coordinatively-saturated and thermodynamically stable luminescent [Ln(dtntp)(H 2 O)] [Ln(III) = Eu (1), Tb (2), Gd (3), Sm (4) and Dy (5)] complexes using an aminophenyl-terpyridine appended-DTPA (dtntp) chelating ligand as cell imaging and photocytotoxic agents. The N,N″ -bisamide derivative of H 5 DTPA named as dtntp is based on 4′-(4-aminophenyl)-2,2′:6′,2 ″ -terpyridine conjugated to diethylenetriamine- N,N′,N″- pentaacetic acid. The structure, physicochemical properties, detailed photophysical aspects, interaction with DNA and serum proteins, and photocytotoxicity were studied. The intrinsic luminescence of Eu(III) and Tb(III) complexes due to f → f transitions used to evaluate their cellular uptake and distribution in cancer cells. The solid-state structure of [Eu(dtntp)(DMF)] (1 ·DMF) shows a discrete mononuclear molecule with nine-coordinated {EuN 3 O 6 } distorted tricapped-trigonal prism (TTP) coordination geometry around the Eu(III). The {EuN 3 O 6 } core results from three nitrogen atoms and three carboxylate oxygen atoms, and two carbonyl oxygen atoms of the amide groups of dtntp ligand. The ninth coordination site is occupied by an oxygen atom of DMF as a solvent from crystallization. The designed probes have two aromatic pendant phenyl-terpyridine (Ph-tpy) moieties as photo-sensitizing antennae to impart the desirable optical properties for cellular imaging and photocytotoxicity. The photostability, coordinative saturation, and energetically rightly poised triplet states of dtntp ligand allow the efficient energy transfer (ET) from Ph-tpy to the emissive excited states of the Eu(III)/Tb(III), makes them luminescent cellular imaging probes. The Ln(III) complexes show significant binding tendency to DNA (K ~ 104 M−1), and serum proteins (BSA and HSA) (K ~ 105 M−1). The luminescent Eu(III) (1) and Tb(III) (2) complexes were utilized for cellular internalization and cytotoxicity studies due to their optimal photophysical properties. The cellular uptake studies using fluorescence imaging displayed intracellular (cytosolic and nuclear) localization in cancer cells. The complexes 1 and 2 displayed significant photocytotoxicity in HeLa cells. These results offer a modular design strategy with further scope to utilize appended N,N,N -donor tpy moiety for developing light-responsive luminescent Ln(III) bioprobes for theranostic applications. [ABSTRACT FROM AUTHOR]

• A red emitting fluorescence probe (TPA-CPO) was designed for HSA. • The recognition mechanism was based on TICT. • TPA-CPO bind IB domain of HSA that avoided the interference of many drugs. • TPA-CPO successfully applied serum protein imaging in HeLa cells. A red emitting fluorescence probe, TPA-CPO, based on twisted intra-molecular charge transfer (TICT) was designed and synthesized. The spectra results displayed that TPA-CPO could sense HSA with excellent properties including significant fluorescence enhancement, long emission wavelength, large stokes shift, and wide linear range. The recognition mechanism was proved that TPA-CPO could bind to domain IB of HSA and its TICT process was suppressed by utilizing hydrophobic cavity and low polarity of HSA. TPA-CPO bind to domain IB instead of common drug sites of HSA could effectively avoid interference from most drugs. The selective response of TPA-CPO allowed quantitative detection of HSA with sensitivity limit of 13.65 µg/mL. What's more, it successfully achieved HSA imaging in HeLa cells. [ABSTRACT FROM AUTHOR]

• A facile gelator (named 2-QF) based on phenylalanine derivative with a Quinoline group synthesized. • 2-QF can assemble to form hydrogels at room temperature with different colors under low pH values. • 2-QF presents as a yellow metallohygrogel (2-QF-Zn) at high pH with Zn2+. • 2-QF can detect Zn2+ ions at physiological pH as a chemosensor. • 2-QF is able to penetrate live HeLa cells and image intracellular Zn2+ ions. Supramolecular hydrogels are attracting soft materials with potential applications. In this study, we synthesized a facile gelator (named 2-QF) based on phenylalanine derivative with a Quinoline group. 2-QF can assemble to form hydrogels at room temperature in different colors under low pH values. Moreover, 2-QF was triggered to form a yellow metallohydrogel (2-QF-Zn) at high pH by the coordination between 2-QF and Zn2+. 2-QF-Zn metallohydrogel showed excellent multi-stimuli responsiveness, especially the reversible "on-off" luminescence switching, as induced by base/acid. In addition, at a low concentration, 2-QF can selectively and visibly identify Zn2+ through fluorescence enhancement, and can detect Zn2+ at physiological pH as a chemosensor. Remarkably, 2-QF and 2-QF-Zn exhibited an excellent biocompatibility without cell cytotoxicity, and 2-QF is able to penetrate live HeLa cells and image intracellular Zn2+ by a turn-on fluorescent response, which makes it a potential candidate for biomedical applications. [ABSTRACT FROM AUTHOR]

The valorization, resource generation and the functional characteristic exploration of domestic waste still face enormous challenges. Kiwi peels, a common kind of fruit waste, contain a large amount of phenolic substances, including polyphenols, flavonoids, etc., which can be explored and reused in food and biomedical fields. By ultrasonic assisted extraction technology, we obtained conversional fluorescence kiwi peel phenolic extracts (PE) which possessed gradient magenta fluorescence relying on the content of ethanol in the solution, as well as strong antioxidant activity. Besides, metal ions sensing assay revealed that PE can specifically sense Hg2+ and Cu2+ (LOD: 1.16 and 0.17 μM, respectively) accompanied with a fluorescence conversion from magenta fluorescence to blue. Moreover, employing the prepared PE as fluorescent probes, imaging of HeLa cells can be easily achieved with satisfactory resolution. Additionally, PE was incorporated into the gelatin matrix, successfully fabricating a green, edible degradable film with excellent antioxidant activity. Unlabelled Image • Ultrasound treatment accelerated the escape of kiwi peel phenolic extracts. • Phenolic extracts exhibited a gradient magenta fluorescence relying on the solvent effects. • Phenolic extracts sense Hg2+ and Cu2+ with a fluorescence conversion from magenta to blue. • Phenolic extracts were successfully applied to fluorescent imaging of HeLa cells. • Phenolic extracts improved the antioxidant capacity of gelatin-based films. [ABSTRACT FROM AUTHOR]

In this paper, a photoinduced electron transfer (PET)& twisted intramolecular charge transfer (TICT)-based fluorescent probe (1) for detecting biothiols (GSH/Cys/Hcy) and hydrogen sulfide with fluorescence turn on was developed. The probe could recognize hydrogen sulfide over primary ions and selectively detect GSH/Cys/Hcy over other amino acids with fluorescence turn-on (an ESIPT process). H 2 S can be distinguished from GSH/Cys/Hcy with wavelength shift by UV–Vis spectra. In addition, detection limits for H 2 S/GSH/Cys/Hcy of probe 1 were 1.42 μM (0–100 μM), 0.13 μM (0–40 μM), 0.27 (0–30 μM), 0.22 μM (0–40 μM), respectively. The proposed thiolysis of the 2,4-dinitrochlorophenyl ether reaction in identification process was verified by the characteristic peak in 1H NMR and HRMS spectra. Finally, the biological imaging experiments and low cytotoxicity investigations in HeLa cells demonstrated that probe 1 could provide a promising method for the determination of H 2 S and biothiols in aqueous solution and living cells. Unlabelled Image • A PET&TICT-based fluorescent probe 1 for H 2 S and GSH/Cys/Hcy has been developed. • Probe 1 possesses a high selectivity toward H 2 S and GSH/Cys/Hcy over amino acids. • The detection limit of probe 1 for H 2 S was 1.42 μM (in a range of 0–100 μM). • The CDL of probe 1 toward GSH/Cys/Hcy were 0.13 μM, 0.27 μM, 0.22 μM, respectivly. • The application of probe 1 for H 2 S imaging in HeLa cells was also achieved. [ABSTRACT FROM AUTHOR]

The systematic studies of chromone appended novel chemosensors, favored to Mg2+ ion detection, these were analyzed and characterized by different spectroscopic techniques such as NMR, mass spectroscopy, FTIR and optical techniques. The binding demeanor of the ligands was executed with the library of metal ions and shown the good coordination with Mg2+ ion to the ligand's cavity. Both ligands demonstrated good binding behavior with Mg2+ ion. The ligands represented 1: 1 stoichiometry with Mg2+ ions through Job's plot. The low limit of detection of Mg2+ ion was determined as 2.56 × 10−6 and 1.28 × 10−6 for L a and L b respectively. No interference was occurred in Inference study by foreign metal ions that supported the specific detection of Mg2+ ion among the other metal ions. Further, the cytotoxicity assay test of these chromone appended ligands revealed that both ligands and their respective compound with Mg2+ ion shown negligible toxicity with HeLa cancer cell line. Further, due to the fluorescence properties of the ligands, with or without Mg2+ ion was successfully tested in bioimaging experiment of HeLa cancer cell lines and found that ligands with Mg2+ ions represented good imaging with HeLa cancer cell. Unlabelled Image • The chromone appended novel molecules have been developed. • Molecules shown selectivity and sensitivity towards magnesium ion among different metal ions. • These chemosensors represented turn-on behavior with the magnesium ion. • The biocompatible behavior of the chemosensors with or without magnesium ion has been represented by cytotoxicity test. • These chemosensors was successfully used in the imaging of HeLa cancer cell. [ABSTRACT FROM AUTHOR]

In this study, a highly selective fluorescent sensor (E)-2-((2-(benzo[ d ]thiazol-2-yl)quinolin-8-yl)oxy)- N ′ -((7-(diethylamino)-2-oxo-2 H -chromen-3-yl)methylene)acetohydrazide (TQC) was synthesized from 2-methylquinolin-8-ol and 4-(diethylamino)-2-hydroxybenzaldehyde and its structure was characterized by 1H NMR, 13C NMR, ESI-HR-MS and density functional theory (DFT) calculation. Sensor TQC showed an obvious "on-off-on" fluorescence response to Cu2+ and PPi in a DMSO/HEPES (3:2 v/v, pH = 7.4) buffer system. The detection limits of sensor TQC were 0.06 μM to Cu2+ and 0.01 μM to PPi. In addition, sensor TQC showed a 1:1 binding stoichiometry to Cu2+ and TQC- Cu2+ complex showed a 2:1 binding stoichiometry to PPi. The optimum pH range of sensor TQC and TQC- Cu2+ was 3–8. Further studies demonstrated that sensor TQC could be made into test paper strips for the qualitative of Cu2+ and PPi and showed sequentially "on-off-on" fluorescent bio-imaging of Cu2+ and PPi in HeLa cells. Unlabelled Image • The sensor TQC could be used to sequential detect Cu2+ and PPi. • The detection limits of sensor TQC were 0.06 μM to Cu2+ and 0.01 μM to PPi. • Test paper strips for the qualitative detection. • Live cell imaging in HeLa cells. [ABSTRACT FROM AUTHOR]

New pyrazole bearing imidazole derivative was successfully synthesized and thoroughly characterized by various spectroanalytical techniques. The sensor DIBI shows a highly selective and sensitive fluorescent response with the addition of Al3+/Fe3+ ions in acetonitrile-water mixture. The strong fluorescent molecule exhibits a notable ratiometric emissions at 462 nm and 470 nm for Al3+ and Fe3+ ions, respectively (λ ex = 280 nm). Job's plot studies conclude that the coordination between DIBI with Al3+/Fe3+ was 1:1 binding stoichiometry. The limit of detection of DIBI with Al3+/Fe3+ was calculated as 2.12 × 10−7 M and 1.73 × 10−6 M, respectively. The TD-DFT calculations further supported the photonics performances of the free probe and its complexes. The reversibility and reusability of the sensor molecule are studied using EDTA. The probe was used to track Al3+/Fe3+ in cancer cells via fluorescence microscopy. We report to the design and synthesis of pyrazole bearing imidazole based derivative for a highly selective and sensitive ratiometric fluorescent response with the addition of Al3+/Fe3+ions. The TD-DFT calculations further supported the photonics properties involved in the free probe and its complexes. The reversibility and reusability of the sensor molecule are studied using EDTA. The probe was used to track Al3+/Fe3+ in living cells via fluorescence microscopy. Unlabelled Image • New pyrazole bearing imidazole based derivative (DIBI) was designed and characterized for the selective detection of Al3+ and Fe3+ ions. • The probe shows good sensitivity for Al3+ and Fe3+ ions with an LOD at 2.12 × 10−7 M and 1.73 × 10−6 M, respectively. • The 1:1 binding model of the sensor DIBI with Al3+/Fe3+ ions was established. • Reversibility of the chemosensor DIBI was verified by experiments with EDTA. • DIBI was successfully recognized to image intracellular Al3+/Fe3+ ions in HeLa cells. [ABSTRACT FROM AUTHOR]

A small molecule fluorescent probe (probe 1) based on adenine-coumarin derivative was designed and synthesized in this paper. Probe 1 exhibited a significant fluorescence-enhancing response to nucleic acids at 495 nm (for DNA) and 487 nm (for RNA). The fluorescence enhancement of probe 1 for DNA and RNA was 5.68 and 9.73 times respectively, the fluorescence quantum yield was changed from 2.5% to 11.7% and 22.5% accordingly. Meanwhile, an excellent linear relationship of fluorescence intensity at 495 nm or 487 nm versus the nucleic acid concentration (1 μM for probe 1 , 0–350 μg/mL for DNA and 0–300 μg/mL for RNA) was obtained. Co-staining and nucleic acid digestion experiments showed that probe 1 could selectively image nucleic acids in mitochondria and nucleoli in HeLa cells. Unlabelled Image • An adenine-coumarin based probe was designed and synthesized. • Excellent light stability and high selectivity for DNA and RNA • Low cell cytotoxicity in HeLa cells • Image DNA in mitochondria of HeLa cells [ABSTRACT FROM AUTHOR]

Hypochlorous/hypochlorite (HClO/ClO−), one of the most important signal molecule, plays a crucial role in many cellular signaling pathways. It is reported that the HClO/ClO− level in mitochondria is important to maintain the normal mitochondrial function. Herein, we present two simple fluorescent probes BAC and mitochondria-targeting fluorescent probe TACB for the detection of ClO−. Probes BAC & TACB could be sensitively and selectivity detecting ClO− at the nanomolar levels with the detection limit of 1.64 × 10−9 M and 9.86 × 10−8 M, respectively. Additionally, probes BAC & TACB with the response unit of C O moiety could selectively detect ClO− over other various analytes such as anions, metal ions and OH, 1O 2 , H 2 O 2. The response time of probe TACB for ClO− (<20 s), implying that it could offer a real-time analytical assay of ClO−. Finally, probe BAC was used for monitoring the ClO− in HEK293T cells and probe TACB could be utilized to track the fluctuations of exogenous ClO− levels in the mitochondria of Hela cells. A new "turn-on" mitochondria-targeting TACB was designed and synthesized for highly specific and sensitive detection of ClO− with fast response time in living cells. Unlabelled Image • Probe BAC & TACB based on coumarin was designed and synthesized. • Probe BAC & TACB display a grateful fluorescence turn on property for ClO- with fast response time and low detection limits. • Probe TACB could be applied for the detection of mitochondrial ClO-. • ESI-MS, DFT and IR were further verified that the oxidation reaction between the C-O of coumarin lactone and ClO-. [ABSTRACT FROM AUTHOR]

A new long-lived Donor–Acceptor (D–A) fluorophore based on carbazolyl dicyanobenzene was developed as an ON–OFF–ON multifunctional fluorescent probe 1 for sequential detection of Cu2+ and biothiols (Cys, Hcy and GSH). The fluorescence of probe 1 can be significantly and selectively quenched by Cu2+. Meanwhile, the fluorescence lifetime decreased from 2.1 μs to 18.5 ns. The limit of detection was determined to be 33.6 nM. Upon addition of biothiols (Cys, Hcy and GSH), the generated ensemble 1-Cu 2+ displayed a "turn-on" fluorescent response at 555 nm and an obvious recovery in fluorescence lifetime and UV–vis absorption within 1 min. The limit of detection for Cys, Hcy and GSH were calculated by fluorescence titration experiments to be 0.19, 0.21 and 0.29 μM, respectively. The ensemble 1 - Cu 2+ was further successfully applied in bioimaging. A new ON–OFF–ON multifunctional fluorescent probe with long-lived was developed for sequential detection of Cu2+ and biothiols (Cys, Hcy and GSH). This probe displayed high selectivity and sensitivity toward Cu2+. In addition, the probe has been successfully applied in HeLa cells. Unlabelled Image • A new TADF compound with long lifetime was synthesized. • A fluorescent probe showed incredible changes of emission lifetime in the detection of Cu2+ and biothiols. • The probe can be used in cell imaging. [ABSTRACT FROM AUTHOR]

A straightforward approach to the fabrication of intrinsically excited-state intramolecular proton transfer (ESIPT)-fluorescent polymer nanoparticles (e-PNPs) was developed. The e-PNPs were obtained by self-assembly of the homopolymers derived from 4-aminosalicylic acid in aqueous solution. By incorporating ESIPT modules into polymer nanoparticles, the ESIPT reaction can be endowed with moderate hydrophobic micro-environment by nanoparticle scaffolds, eliciting enhanced ESIPT emission. The newly developed e-PNPs exhibit strong tautomeric fluorescence(e-FL), good photostability, low-toxicity and favourable biocompatibility in aqueous solution. Upon the addition of NO 2 -, the e-FL can be significantly quenched owing to the reaction of NO 2 - with the amide groups on e-PNPs. From this basis, the fluorescence detection of NO 2 - was implemented, which showed a linear relationship between 0 nM and 110 nM with a detection limit of 2.3 nM. Furthermore, e-PNPs were used as nanoprobes to monitor the NO 2 - levels in HeLa cells by fluorescence imaging, demonstrating the ability of discrimination from different concentrations of NO 2 -. The proposed method can be applied to a wide range of other ESIPT modules to integrate into polymer nanoparticles and offer highly sensitive nanosensing platform for bioanalysis and molecular imaging. Intrinsically ESIPT-fluorescent polymer nanoparticles (e-PNPs) were prepared using 4-aminosalicylic acid. The e-PNPs exhibit strong tautomeric fluorescence, high sensitivity to nitrite, low-toxicity and favourable biocompatibility, making them an outstanding candidate for designing nanoprobes for nitrite detection. Image 1 • A facile and efficient approach to the preparation of intrinsically ESIPT-exhibiting polymer nanoparticles (e-PNPs) was developed. • The e-PNPs showed enhanced ESIPT emission, good photostability, low-toxicity and favourable biocompatibility. • By using e-PNPs as nanoprobes, a highly sensitive method for the determination of nitrite was established based on tautomeric emission quenching mechanism. [ABSTRACT FROM AUTHOR]

Inspired by the conversion from organics or biomass to fluorescent carbon dots (C-dots), the use of pesticide 4-chlorophenol (4-CP) as a precursor to prepare C-dots has been reported. The as-prepared chlorine-doped C-dots display a brightly blue emission at ∼445 nm with ∼22.8% quantum yield. Also, the surface of C-dots enriches functional groups, such as phenolic hydroxyl and carboxylic acid, etc., which can capture ferric ion (Fe(III)), resulting in the quenching of blue fluorescence of C-dots through an inner filter effect. The quantitative assay for Fe(III) was therefore realized by this probe with a 0.36 μM detection limit in the 0.6–25 μM concentration range. Most significantly, the cytotoxicity on Hela cells indicates the 4-CP-derived C-dots have a negligible cytotoxicity. The C-dots were applied in detection in environmental samples and imaging in Hela cells of Fe(III), demonstrating their good applicability, low toxicity and good biocompatibility, and providing an alterative approach to totally eliminate the harm of chlorophenols (CPs). Image 1 • 4-CP -derived chlorine-doped C-dots were reported. • 4-CP-derived C-dots can emit brightly blue light with 22.8% QY. • 4-CP-derived C-dots owned much lower cytotoxicity than 4-CP. • 4-CP-C-dots were applied in Fe(III) imaging in Hela cells. [ABSTRACT FROM AUTHOR]

A simple chemosensor, 6-(1H-pyrrol-2-yl)-5,6-dihydro-benzo[4,5]imidazo[1,2-c]quinazoline (1), was synthesized via simple nucleophilic addition reaction coupled with Schiff base condensation. The probe 1 is aggregation-induced emission-active and could be used as an on–off fluorescence sensor toward Cu2+ in H 2 O/CH 3 CN (99.5%, v/v) solution. Furthermore, the resultant Cu2+ complex selectively responded to pyrophosphate (PPi) among various anions based on fluorescent on–off signal. In addition, the probe could be used for detecting Cu2+ and PPi in HeLa cells. Image 1 • A quite simple pyrrole-quinazoline-based fluorescent probe for Cu2+ and pyrophosphate has been developed. • The crystal structures of the probe and its Cu2+ complex were reported. • The probe is an aggregation-induced emission enhancement active compound. • The probe has been used for imaging of Cu2+ and pyrophosphate in living cells. [ABSTRACT FROM AUTHOR]

Three 5 H -benzo[a]phenoxazin-5-one-based (benzoresorufin and nile-red) Cysteine (Cys) detection probes have been comparatively designed and synthesized in this paper. The optical experiments exhibit probe 1b with a crotonoyl group has no response toward Cys; while probes 1a and 1c have the same reaction site (acryloyl group), their optical responses to Cys are quite different. The benzoresorufin-based-probe 1a shows a turn-on fluorescence response (118-fold) to Cys at 631 nm and affords a very low detection limit (DL = 19.8 nM). Compared with probe 1a , the nile-red-based probe 1c displays gradually diminishing fluorescence intensity with increased Cys concentration at 665 nm. And the notable different fluorescence response mechanisms of probes 1a and 1c toward Cys can be interpreted by HRMS and time-dependent density functional theorety (TDDFT) calculations. Furthermore, both of the two probes indicate high sensitivity and selectivity toward Cys over other similar structured amino acids including homocysteine (Hcy) and glutathione (GSH). Further cellular applications of the two probes have been successfully performed in HeLa cells. Image 1 • Three Cys probes 1a − c based on benzoxazine (benzoresorufin and nile-red) were comparatively designed, synthesized and investigated, and the mechanism was proposed. • Their different responses to Cys could indicate that the same fluorophore with different auxochrome groups and detection groups have different properties. • Probes 1a and 1c exhibited high selectivity for Cys, and 1a had a low detection limit of 19.8 nM. • Off-on and attenuation response; long emission wavelength; cell imaging. [ABSTRACT FROM AUTHOR]

Cysteine has a great effect on the physiological and pathological processes, which could bring out various diseases such as skin lesions, edema, hair depigmentation, Alzheimer's, Parkinson's, and liver damage due to the abnormal concentrations of cysteine. Therefore, it is of great impoatance to develop a method for imaging Cys. Herein, a novel fluorescent probe was developed for imaging Cys in vivo specially. This turn-on probe exhibited favorable advantages including large Stokes shift (90 nm), fast response (10 min), good selectivity, low cytotoxicity and so on. Furthermore, the probe could be applied to monitoring cysteine in living HeLa cells, which indicates that this turn-on probe could penetrate viable cell membranes and image Cys over other analystes especially HCy and GSH. Unlabelled Image • A novel fluorescent probe NBDS was developed for imaging Cys in vivo specially exhibiting favorable advantages including large Stokes shift (90 nm), fast response (10 min), good selectivity, low cytotoxicity. • This turn-on probe exhibited favorable advantages including large Stokes shift (90 nm), fast response (10 min), good selectivity, low cytotoxicity. • In vivo cell imaging indicates that the probe NBDS could be suitable to reveal the vital role of Cys in various physiological processes. [ABSTRACT FROM AUTHOR]

Ag+ and SCN− play extremely important roles in the fields of the physiology and environment. In this work, on the basis of phenanthro[9,10- d ]imidazole derivative (DIPIP) which can exhibit the aggregation-induced emission (AIE) properties in aqueous solution, we achieved a sequential on-off-on switch for Ag+ and SCN− with high selectivity and sensitivity. A remarkable fluorescence quenching effect of Ag+ on the probe DIPIP was observed with 1:2 stoichiometry, Subsequently, the fluorescence intensity of in situ generated DIPIP -Ag+ ensemble was easily switched on after the interaction between Ag+ and SCN−, which was attributed to the stronger affinity of SCN− to capture Ag+. In particular, the extreme limits of detection (LOD) for Ag+ and SCN− in standard solutions were as low as to be 74.5 nM and 7.8 nM, respectively. Furthermore, the probe DIPIP and the DIPIP -Ag+ ensemble could be used to detect Ag+ in the real water and SCN− in smoker saliva samples, respectively. In addition, the sequential "on-off-on" fluorescence mode of DIPIP to Ag+ and SCN− were also successfully applied in living HeLa cells. Unlabelled Image • Fluorescent probe DIPIP was designed and prepared; • DIPIP had obvious AIE activity; • A "on-off-on" sequential detection for Ag+ and SCN– with the extreme lower LOD was studied; • The responses of DIPIP to Ag+/AgNPs and of Ag+ to SCN− were applied in water and saliva samples. • Mode of the sequential sensing was realized in cells imaging. [ABSTRACT FROM AUTHOR]