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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] • A novel turn-on near-infrared fluorescent probe TQ-AChE was developed to detect endogenous AChE. • The probe had high selectivity and sensitivity to AChE (LOD = 0.02 U/mL) and a fast response time (30 min). • In vivo studies in mouse models validate the potential of the probe in real-time monitoring of AChE expression in liver injury. Acetylcholinesterase (AChE) is a key enzyme in the cholinergic pathway of the nervous systems, with its aberrant expression linked to various diseases. In this study, we have developed a novel Turn-On near-infrared fluorescent probe, TQ-AChE, for the sensitive and selective detection of AChE activity. Characterized by its near-infrared emission at 740 nm, TQ-AChE effectively overcomes the limitations of traditional fluorescent probes, such as short excitation wavelengths and limited tissue penetration, crucial for both in vitro and in vivo applications. The probe's low limit of detection (LOD) of 0.02 U/mL for AChE makes it highly sensitive, enabling rapid quantification of AChE activity in serum effectively. Cell imaging studies demonstrate that TQ-AChE can confirm higher AChE activity expression in normal liver cells compared to liver cancer cells. TQ-AChE can also monitor AChE fluctuations in APAP-induced acute effectively, facilitating the evaluation of the efficacy of liver detoxifying agents. Additionally, in vivo studies in mouse models validate the potential of the probe in real-time monitoring of AChE expression in liver injury. The ability of TQ-AChE to visualize AChE expression signifies its potential as a promising tool for early liver disease diagnosis and therapeutic monitoring, opening new possibilities in hepatological research and clinical diagnostics. [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]

[Display omitted] • Developed FDCM-BChE, a near-infrared probe, for accurate BChE quantification in serum. • The probe features rapid response and high selectivity, enhancing fluorescence-based BChE assays. • Employed FDCM-BChE in cellular imaging to reveal BChE downregulation in liver cancer and hepatic injury. • Demonstrated the probe's utility in identifying elevated BChE levels in diabetic subjects. Butyrylcholinesterase (BChE) is a crucial hydrolytic enzyme predominantly synthesized in the liver, playing a significant role in conditions like liver disorders, diabetes, Alzheimer's disease, and fat metabolism regulation. This study aims to address the current limitations in visualizing BChE activity in diseases at various states by introducing an ultra-sensitive near-infrared fluorescent probe, FDCM-BChE. The probe was engineered to have several properties, such as a large Stokes shift, rapid response time, high stability, excellent selectivity, and low detection limits. We validated the efficacy of FDCM-BChE in quantifying BChE activity in human serum and leveraged its low cytotoxicity for cellular imaging. The study revealed the downregulation of BChE activity in liver cancer and hepatic injury and the upregulation in diabetes. Thus, FDCM-BChE shows promise as a tool for specific applications, providing insights into diseases associated with BChE activity. [ABSTRACT FROM AUTHOR]

[Display omitted] • Successful synthesis and characterization of a new fluorescent probe, NR-ClO, for ClO– detection in biological systems. • NR-ClO demonstrated low cytotoxicity, high selectivity, and sensitivity to ClO–. • Confirmed applicability of NR-ClO in both in vitro HepG2 cell studies and in vivo mouse model of rheumatoid arthritis. This study presents the synthesis and application of a novel fluorescent probe, NR-ClO, for the detection of hypochlorite ion (ClO–) in biological systems. The probe was synthesized through a nucleophilic substitution reaction between Nile red and dimethylcarbamothioic chloride. The synthesized probe had high sensitivity and selectivity towards ClO–, with a detection limit of 75 nM and a linear range of 0.1–200 μM. The probe's efficacy was validated through in vitro studies using HepG2 cells and in vivo experiments using a mouse model of rheumatoid arthritis. The findings demonstrate that the NR-ClO probe is a promisingly reliable tool for real-time monitoring of ClO– in complex biological environments. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel Al3+ Schiff base probe JHK was designed and synthesized. • JHK has high selectivity, high fluorescence quantum yield and low detection limit for Al3+. • JHK was successfully applied to living cells and zebrafish. A novel fluorescent probe N'-(2-hydroxybenzylidene)-indole-3-formylhydrazine (JHK) was designed and synthesized based on the condensation reaction of indole-3-formylhydrazine and salicylaldehyde. The probe JHK solution could highly selectively recognize Al3+ by the obvious fluorescence enhancement (288-fold) after adding Al3+. And the probe solution with Al3+ had a very high fluorescence quantum yield (89.29 %). The detection limit was calculated to be 1.135 nM, which was significantly lower than many reported detection limits, indicating that the probe JHK had pretty good sensitivity. The ratio of JHK to Al3+ (1:1) and the sensing mechanism were determined by Job's plot, 1H NMR spectra, FTIR spectra, ESI-MS and Gaussian calculation. The probe solution and medium-speed filter paper were successfully used to make test papers for more convenient detection of Al3+. Furthermore, the probe JHK had been successfully applied to the detection of Al3+ in real water, zebrafish and living cells. [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] • An efficient dual-function fluorescent probe SN-F for SO 2 derivatives and H 2 S. • SN-F had a swift response (2 min), strong selectivity and anti-interference capability for SO 2 derivatives. • Probe SN-F had a wide linear range for H 2 S. • Probe SN-F had superior endoplasmic reticulum-targeting. As gas signaling molecules in organisms, SO 2 derivatives and H 2 S play crucial regulating roles in a series of physiological processes. Therefore, developing an assay that can accurately monitor the concentration of SO 2 derivatives and H 2 S in cells is extremely important for the research and treatment of related illnesses. A bifunctional probe SN-F based on FRET mechanism for SO 2 derivatives and H 2 S was designed. SN-F had a short response time to SO 2 (2 min), excellent anti-interference capability and selectivity in the non-organic solvent system (pH = 7.4), which was suitable for the determination of SO 2 derivatives in cells. SN-F had a wide linear range for H 2 S. Moreover, SN-F was applied in cell imaging successfully with high targeting ability to endoplasmic reticulum (ER) and could monitor endogenous and exogenous H 2 S in cells. [ABSTRACT FROM AUTHOR]

[Display omitted] • The probe 3-STF is first designed based on 3-thiolflavone. • The probe 3-STF exhibited a specific "turn-on" fluorescence response towards biothiols (Cys, Hcy, and GSH) with a large stokes shift of 140.6 nm. • The detection of biothiols did not suffer from the interference of other amino acids. • The detection mechanism was discussed in detail. • The probe 3-STF can be successfully applied to monitor endogenous and exogenous biothiols in HepG-2 cells. Abnormal levels of intracellular biothiol species, including glutathione (GSH), homocysteine (Hcy), and cysteine (Cys), are closely relevant to a variety of diseases. In this study, we first report the design and synthesis of a 3-thiolflavone-based probe 3-STF with an S–S linkage both as the fluorescence quenching agent and the recognition site. Upon treatment with biothiols, the S–S linkage was cleaved by nucleophilic attack of RS-, and 3 -STF exhibited a specific "turn-on" fluorescence response at 543.8 nm upon 390 nm excitation. Meanwhile, 3 -STF was proved to be highly sensitive and selective for the detection of biothiols over other nucleophiles such as amino acids and H 2 S. The sensing mechanism was further verified by 1H NMR and ESI-MS analysis. In addition, 3-STF with low cytotoxicity can be successfully applied to detect endogenous and exogenous biothiols in HepG-2 cells. [ABSTRACT FROM AUTHOR]

[Display omitted] • A fluorescent probe NBPI, utilizing cyanine phenothiazine and 7-nitro-1,2,3-benzoxadiazole (NBD), was developed for selective detection of Cys-SO 2 components. • The phenothiazine structure increased the bond energy of sulfonamide, thus the probe NBPI achieved a selective response to Cys. • The probe NBPI was successfully employed for the imaging of endogenous and exogenous Cys and SO 2 in HepG2 cells. A fluorescent probe has been designed using cyanine phenothiazine and 7-nitro-1,2,3-benzoxadiazole (NBD) for selective detection of Cys-SO 2 components. The probe utilizes the NBD structure to achieve specificity towards Cys and employs a reaction mechanism between the double bond of cyanine and phenothiazine with SO 3 2− to achieve selectivity towards SO 2. Importantly, the NBPI phenothiazine structure incorporates a large C-O bond energy attached to NBD, effectively eliminating interference from Hcy and ensuring highly selective response to Cys. The optimized design of the probe enables excellent linearity and extremely low detection limits for Cys-SO 2 components in vitro experiments. The probe NBPI allows separate detection of Cys-SO 2 in the presence of both components. Furthermore, the probe NBPI demonstrated successful imaging of endogenous and exogenous Cys and SO 2 in cell studies. [ABSTRACT FROM AUTHOR]

[Display omitted] • An "off–on" long-wavelength fluorescent probe is synthesized for Cys detection. • The probe has a large Stokes shift (211 nm) and reacted with Cys specifically. • The probe can monitor Cys fluctuations caused by redox imbalance in HepG2 cells. • The probe can be used for fluorescence imaging in cells and mice. In this research, an "off–on" long-wavelength fluorescent probe (DCMN-Cl) based on (E)-2-(3-(2-(6-hydroxynaphthalen-2-yl)vinyl)-5,5-dimethylcyclohex-2-en-1-ylidene) malononitrile (DCMN) is designed and synthesized for cysteine (Cys) detection. DCMN-Cl exhibits a large Stokes shift (211 nm) and shows rapid response and high specificity to Cys. The fluorescence initensity at 635 nm reveals a good linear relationship with Cys concentration in the 0 to 50 μM range, and the detection limit is as low as 159 nM. The probe is also used for fluorescence imaging of Cys in cells and mice. Moreover, the probe provided visual evidence of Cu2+ and curcumin-induced intracellular Cys fluctuations. [ABSTRACT FROM AUTHOR]

[Display omitted] • A fluorescent probe ( CyNa-N 3 ) based on naphthalimide and cyanine dyes was synthesized. • CyNa-N 3 can detect HClO and H 2 S with different fluorescence signals. • The sensing mechanism of CyNa-N 3 to HClO and H 2 S was confirmed by ESI–MS and 1H NMR. • CyNa-N 3 was adapted to visualize HClO and H 2 S in cell imaging. Hypochlorous acid (HClO) and hydrogen sulfide (H 2 S) play very important roles in both physiological and pathological processes, however, the methods for simultaneously detecting HClO and H 2 S were rarely reported. Here, a dual–responsive fluorescent probe ( CyNa-N 3 ) based on cyanine and naphthalimide dyes was synthesized and investigated. The fluorescence probe showed better sensitivity, high selectivity response to HClO and H 2 S by red emission and green emission bands, and the limits of detection were 0.17 µM and 0.15 µM respectively. MS (Mass Spectrum) and 1H NMR (Nuclear Magnetic Resonance) confirmed the sensing mechanism of CyNa-N 3 detected HClO and H 2 S, the calculation of density functional theory (DFT) further explained the internal mechanism of spectral change of CyNa-N 3 . Moreover, CyNa-N 3 was successfully applied to image HClO and H 2 S in living cells, which is beneficial for more efficient application in biological imaging. [ABSTRACT FROM AUTHOR]

[Display omitted] • A robust probe Bptp-RD was developed to identify DNA and RNA. • Bptp-RD was successfully applied to image DNA and RNA in cells. • Bptp-RD was successfully used to detect different types of DNA. • Recognition rule of probes to different types of DNA was revealed with Bptp-RD. The roles of deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) in cells are closely related. However, the absence of molecular tools for simultaneous imaging of the two nucleic acids has prevented scientists from elucidating the regulatory mechanisms of nucleic acid interaction. The nucleic acid probes developed in recent years have ignored the regulatory relationship between DNA and RNA. Simultaneously imaging RNA and DNA in cells through a single small-molecule fluorescent probe is important. In this study, we propose a strategy for developing fluorescent probes localized to DNA and RNA to investigate their detection and imaging characteristics. The novel probe Bptp-RD has been successfully used for DNA and RNA imaging in cells. We investigated the detection and imaging characteristics of this nucleic acid probe and discovered the following: 1) the differences in the detection results of this nucleic acid probe for DNA and RNA come from the structural differences of the nucleic acids rather than chemical composition differences; 2) through using small-molecule probes to image a nucleic acid in cells, another nucleic acid can be visualized by reducing the fluorescence signal caused by DNA or RNA; 3) the order of response of the small-molecule fluorescent probe with intercalation and binding mechanisms to the type of nucleic acid structure is single chain, double chain, and ring. This work will help improve the understanding of RNA and DNA probes, and the novel probe has high potential to explore the interaction between RNA and DNA in cells. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel mitochondria-targeted red-emitting fluorescent probe (VP) was synthesized. • The probe VP was used to detect viscosity with high selectivity and sensitivity. • The probe VP could visualize the mitochondrial viscosity change in living cells. • The probe VP was a potential tool for monitoring viscosity and phagocytosis. Mitochondrial viscosity is a critical factor affecting numerous physiological processes, including phagocytosis. Abnormal viscosity in mitochondria is related to some pathological activities and diseases. Evaluating and detecting the changes in mitochondrial viscosity in vivo is crucial. Thus, a mitochondria-targeted red-emitting fluorescent probe (VP) was prepared, and can be used to detect viscosity with high selectivity and sensitivity. The synthesis of probe VP was as simple as two steps and the cost was low. In addition, the fluorescence intensity (log I 615) exhibited an excellent relationship with viscosity (log η) in the range of 0.5 – 2.5 (R2 = 0.9985) in water/glycerol mixture. It is noteworthy that the probe VP displayed the highest signal-to-noise ratio (about 50-fold) for viscosity in water and glycerol system. The probe VP can visualize the mitochondrial viscosity change in living cells. More importantly, phagocytic test for BV2 cells further demonstrated that phagocytosis decreased with increased viscosity. Furthermore, VP was successfully used for monitoring the mitophagy process induced by starvation, and mitochondrial viscosity exhibited enhancement during mitophagy. The probe was a potential tool for studying viscosity and phagocytosis. [ABSTRACT FROM AUTHOR]

A terpyridyl-rhodamine based probe has been designed and prepared for the sensitive and discriminative detection of Hg2+ and Cu2+ in water by dual/single emission change and applications in constructing a combinatorial logic gate and cell imaging. [Display omitted] • A new terpyridyl-rhodamine hybrid dye TR and sensor TRH have been facilely prepared. • TRH can discriminatively sense Hg2+ and Cu2+ in water with high sensitivity. • TRH can be employed for the construction of a combinatorial logic gate. • TRH can be applied for the discriminative sensing of Hg2+ and Cu2+ in living cells. Sensitive and discriminative sensing of more than one analyte with a single fluorescent probe is significant and challenging. Herein a new terpyridyl-rhodamine hybrid, namely TRH, has been rationally designed and prepared with two responsive groups in the molecular structure, which facilitate the discriminative detection of Hg2+ and Cu2+ ions in water with detection limits of 4.9 and 53.3 nM by ratiometric fluorescence change (F 595 /F 485) and fluorescence quenching, respectively. Investigations show that the selectivity to Hg2+ ions can be attributed to Hg2+-promoted spirolactam ring opening and further hydrolysis, followed by a through-bond energy transfer (TBET) process. The selective fluorescence quenching to Cu2+ ions probably can be ascribed to the binding Cu2+ to terpyridyl that triggers a ligand-to-metal charge transfer (LMCT) process, which can also efficiently inhibit the TBET process induced by Hg2+ ions and promotes the discriminative sensing of Cu (II) and Hg (II). In addition, the fluorescent responses to Hg2+ and Cu2+ ions cover a wide pH range. Moreover, a combinatorial logic gate with the functions of NOR and INHIBIT has been fabricated by using Hg2+ and Cu2+ ions as chemical input signals, and fluorescence at 485 and 595 nm as output signals. Besides, TRH also exhibits sensitive and discriminative sensing ability to Hg2+ and Cu2+ ions by the fluorescence of rhodamine fluorophore. Significantly, based on the fluorescence signal output of rhodamine moiety, TRH can be used as a tracer for the discriminative sensing of Hg2+ and Cu2+ ions by using living cells. [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]

[Display omitted] • Probes 1a-b for detection of thiophenols by ESIPT mechanism were constructed with diethylcoumarin–salicylaldehyde units. • They showed large Stokes shift (greater than100 nm) and one of them displayed NIR-emitting (670 nm) when detecting thiophenols. • Probes 1a-b could form inclusion complexes with M-β-CD. • The presence of M-β-CD reduced the detection limits of probes 1a - b towards thiophenols. Thiophenol and its derivatives are compounds with high toxicity to organisms and environmental pollution, so it is necessary to detect the level of thiophenols in the environment and biological samples. The probes 1a-b were obtained by introducing the 2,4-dinitrophenyl ether group into diethylcoumarin–salicylaldehyde based compounds. And they can form host-guest compounds with methylated β-cyclodextrin (M-β-CD), the association constants of inclusion complexes are 49.2 M−1, 125 M−1 respectively. The fluorescence intensities of probes 1a-b at 600 nm (1a) and 670 nm (1b) increased significantly in thiophenols detection. Meanwhile, with the addition of M-β-CD, the hydrophobic cavity of M-β-CD significantly increased the fluorescence intensity of probes 1a-b , thus the detection limits of probes 1a-b to thiophenols were reduced from 410 nM, 365 nM to 62 nM, 33 nM respectively. Whereas, the good selectivity and short response time of probes 1a-b towards thiophenols was not affected in the presence of M-β-CD. Moreover, probes 1a-b were used for further water sample detection and HeLa cell imaging experiments due to their good response to thiophenols and the results suggested that probes 1a-b had the potential to detect the content of thiophenols in water samples and living cells. [ABSTRACT FROM AUTHOR]

On the basis of classical Schiff base reaction, two novel and efficient fluorescent probes (DQNS , DQNS1) were designed and synthesized by introducing Schiff base structure into dis-quinolinone unit for structural modification, which can be used to detect Al 3+ and ClO −. [Display omitted] • The double-recognition fluorescent probes with the same site designed based on ICT and PET mechanism has the characteristics of simple synthesis method. • Preliminary speculation, the probe (DQNS) has continuity in identifying Al3+and ClO−. • The probes (DQNS) can primarily screen and analyze environmental samples and living cells containing Al3+and ClO−. On the basis of classical Schiff base reaction, two novel and efficient fluorescent probes (DQNS , DQNS1) were designed and synthesized by introducing Schiff base structure into dis-quinolinone unit for structural modification, which can be used to detect Al3+ and ClO−. Because the power supply capacity of H is weaker than that of methoxy, DQNS shows better optical performance: a large Stokes Shift (132 nm), identify Al3+ and ClO− with high sensitivity and selectivity, low detection limit (29.8 nM and 25 nM) and fast response time (10 min and 10 s). Through the working curve and NMR titration experiment, the recognition mechanism of Al3+ and ClO− (PET and ICT) probes are confirmed. Meanwhile, it is speculated that the probe has continuity for the detection of Al3+ and ClO−. Furthermore, DQNS detection of Al3+ and ClO− was applied to real water samples and living cell imaging. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new benzobodipy-based HOCl fluorescent probe has been designed and developed. • The probe exhibits an excellent sensitivity and low detection limit to HOCl. • The probe could be applied for real-time fluorescence imaging of HOCl in live cells and zebrafish. Hypochlorous acid (HOCl) is an essential endogenous reactive oxygen species in biological systems, playing a critical role in various physiological processes. Real-time monitoring of HOCl concentration in living organisms is essential for understanding its biological functions and pathological roles. In this study, we developed a novel fluorescent probe based on benzobodipy, BBDP , for rapid and sensitive detection of HOCl in aqueous solutions. The probe exhibited a significant fluorescence turn-on response to HOCl based on its specific oxidation reaction towards diphenylphosphine, with high selectivity, instantaneous response (less than 10 s), and low detection limit (21.6 nM). Furthermore, bioimaging results illustrated that the probe could be applied for real-time fluorescence imaging of HOCl in live cells and zebrafish. The development of BBDP may provide a new tool for exploring the biological functions of HOCl and its pathological roles in diseases. [ABSTRACT FROM AUTHOR]

[Display omitted] The biological microenvironment includes important parameters such as viscosity, polarity, temperature, oxygen content and pH. In particular, abnormal cell viscosity is associated with the development of major diseases. Sulphur dioxide (SO 2) serves not only as an essential atmospheric pollutant but also an influential signalling molecule in biological cells, predisposing individuals to increased respiratory disease. In this work, we designed and synthesized a novel fluorescent probe CouCN-V&S with dual response to micro environmental viscosity and SO 2. The probe monitored viscosity and SO 2 separately through dual emission channels with a difference of 135 nm. The probe responded sensitively to SO 2 (<1s) and exhibited satisfactory immunity to interference and pH stability. The probe was successfully applied to imaging cellular, intra-zebrafish viscosity and SO 2 changes. Interestingly, we took onion epidermal cells as model and explored the capability of probe CouCN-V&S to image SO 2 in plant cells for the first time. [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] • A near-infrared ratiometric fluorescent probe (DCPBCl 2 -Hz) was developed. • DCPBCl 2 -Hz exhibited excellent sensitivity and selectivity for hydrazine. • The probe can monitor gaseous hydrazine with a content down to 1 ppm (mg/m3). • The probe was applied for detecting hydrazine in solid and in live cells. Hydrazine (N 2 H 4) is a widely used raw material in the chemical industry, but at the same time hydrazine has extremely high toxicity. Therefore, the development of efficient detection methods is crucial for monitoring hydrazine in the environment and evaluating the biological toxicity of hydrazine. This study reports a near-infrared ratiometric fluorescent probe (DCPBCl 2 -Hz) for the detection of hydrazine by coupling a chlorine-substituted D-π-A fluorophore (DCPBCl 2) to the recognition group acetyl. Due to the halogen effect of chlorine substitution, the fluorophore has an elevated fluorescence efficiency and a lowered pKa value and is suitable for physiological pH conditions. Hydrazine can specifically react with the acetyl group of the fluorescent probe to release the fluorophore DCPBCl 2 , so the fluorescence emission of the probe system significantly shifted from 490 nm to 660 nm. The fluorescent probe has many advantages, such as good selectivity, high sensitivity, large Stokes shift, and wide applicable pH range. The probe-loaded silica plates can realize convenient sensing gaseous hydrazine with content down to 1 ppm (mg/m3). Subsequently, DCPBCl 2 -Hz was successfully applied to detect hydrazine in soils. In addition, the probe can also penetrate living cells and allow the visualization of intracellular hydrazine. It can be anticipated that probe DCPBCl 2 -Hz will be a useful tool for sensing hydrazine in biological and environmental applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • A series of probes NR-BS for H 2 S n were synthesized based on Nile red skeleton. • NR-BS4 can detect H 2 S n with high selective, wide linear range and broad pH tolerance. • The detection mechanisms of NR-BS4 were proved by LC-MS and DFT calculations. • NR-BS4 is a powerful tool for detecting the H 2 S n in living cells and zebrafish. Hydrogen polysulfide (H 2 S n , n > 1) has a valuable function in various aspects of biological regulation. Therefore, it is of great significance to realize the visual monitoring of H 2 S n levels in vivo. Herein, a series of fluorescent probes NR-BS were constructed by changing types and positions of substituents on the benzene ring of benzenesulfonyl. Among them, probe NR-BS4 was optimized due to its wide linear range (0 ∼ 350 μM) and little interference from biothiols. In addition, NR-BS4 has a broad pH tolerance range (pH = 4 ∼ 10) and high sensitivity (0.140 μM). In addition, the PET mechanism of probe NR-BS4 and H 2 S n was demonstrated by DFT calculations and LC-MS. The intracellular imaging studies indicate that NR-BS4 can be successfully devoted to monitor the levels of exogenous and endogenous H 2 S n in vivo. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new benzo-bodipy based fluorescent probe for HClO has been designed and developed. • The probe has excellent sensitivity and a fast response to HClO. • The probe was applied to the fluorescence imaging of HClO in HeLa cells and zebrafish. Due to the highly significant biological activity of hypochlorous acid, the monitoring of its concentration in vivo has received extensive attention. In this work, a photoinduced electron transfer (PeT) based benzo-bodipy fluorescent probe BBy-T has been developed for the rapid, sensitive, and selective detection of HClO in an aqueous solution. Based on the HClO-specific oxidation reaction, BBy-T exhibited a distinct fluorescence turn-on response to HClO with a remarkable Stokes shift (84 nm), immediate response (less than 20 s), and low detection limit (13.7 nM). In addition, the bioimaging results indicated that the probe BBy-T could be applied to real-time fluorescence imaging of living HeLa cells as well as living zebrafish. [ABSTRACT FROM AUTHOR]

Abstract In this study, we report a sequential and reversibility fluorescent probe (DP5) based on pentapeptide conjugated with dansyl groups using the solid phase peptide synthesis (SPPS) technology. DP5 showed immediate "turn off" response toward Cu2+ ions at an excitation wavelength of 330 nm with detection limits of 23.5 nM. The 2:1 binding ratio between DP5 and Cu2+ were confirmed using Job's plot method and fluorescence titration study, and DP5 -Cu complex was observed with an association constant of 6.76 × 108 M−2. As designed, DP5 -Cu complex as a promising analytical probe exhibited highly selective for H 2 S detection in aqueous solutions. The detection limit for H 2 S was obtained to be 17.2 nM, and lower than EPA and WHO guidelines. In addition, the reversibility and cyclicity were imparted to the DP5 during the detection of Cu2+ and H 2 S, and cycle effect is very good. Furthermore, DP5 displayed better biocompatibility and low biotoxicity, and sequential fluorescence "on-off-on" responses of DP5 to Cu2+ and H 2 S were successfully applied in two different living cells. Graphical abstract Unlabelled Image Highlights • A novel peptide fluorescent probe DP5 was synthesized. • DP5 exhibited selective fluorescent "on-off-on" response toward Cu2+and H 2 S. • The detection limits of Cu2+ and H 2 S were 23.5 nM and 17.2 nM respectively. • The reversibility process of DP5 with Cu2+ and H 2 S were confirmed. • DP5 could detect Cu2+ and H 2 S in two different living cells. [ABSTRACT FROM AUTHOR]

Abstract Novel cyanine-based fluorescent probes for the detection of H 2 S were developed. The probes developed are stable under physiological conditions. The water soluble fluorescent probe 2 displayed ultrafast and specific response to H 2 S displaying NIR fluorescence of 115-fold turn-on with the detection limit of 11 nM without assistance of organic solvent or surfactant. Cell imaging experiments indicated that probe 2 was cell-permeable and was able to detect H 2 S sensitively in lysosomes. Moreover, our probe was able to detect H 2 S intrinsically produced H 2 S through enzymatic/non-enzymatic biosynthetic pathway from Cys/GSH. Moreover, we applied probe 2 to detect H 2 S in living mice and demonstrated the fast metabolism of H 2 S. Thus, probe 2 shows great promise as a reporter for H 2 S. Graphical abstract Unlabelled Image Highlights • A novel water soluble cyanine-based NIR fluorescent probe for H 2 S. • Ultrafast and specific response to H2S with low detection limit in PBS buffer. • Lysosome-targeted and capable of detecting H 2 S (both enzymatic/non-enzymatic biosynthesized). • Visualization of H 2 S in living mice and demonstrated fast metabolism of H 2 S. [ABSTRACT FROM AUTHOR]

Abstract Hydrazine and its derivatives are one of the most important raw chemical materials that have extensive utilization in many areas. It is also widely applied as pharmaceutical derivatives, such as the antipsychotic drug, anti-infective drug, and antitumor drug. However, hydrazine is a highly toxic reagent which can bring severe damage to human and animals. Herein, we have reported a new benzothiazole substituted naphthalene based probe for hydrazine with huge fluorescence change ratio. The fluorescence change ratio at F 390 /F 509 is up to 200-fold in the presence of hydrazine in 60 min. The probe exhibited negligible cytotoxicity toward HeLa cells and was applied for hydrazine detection successfully in HeLa cells. Graphical Abstract Unlabelled Image Highlights • A ratiometric fluorescent probe highly sensitive to hydrazine has been designed and developed. • The fluorescence change ratio could be up to 200-fold in the presence of hydrazine. • The fluorescent probe exhibited negligible cytotoxicity and was successfully applied for hydrazine detection in HeLa cells. [ABSTRACT FROM AUTHOR]

Abstract A new ratiometric fluorescent probe (1) was developed for the detection of hydrazine. The probe was obtained by incorporating the recognition moiety of acetyl group onto a coumarin fluorophore. Probe 1 displayed a distinct cyan emission in a 100% aqueous phosphate buffer solution. In the presence of hydrazine, probe 1 undergoes a hydrazinolysis process to release the coumarin fluorophore, which exhibited significant hypsochromic shifts in both absorption and emission spectra, and thus achieving a ratiometric response. This ratiometric probe is highly selective and sensitive towards hydrazine detection. The limit of detection (LOD) was calculated to be 34 nM. Moreover, cellular toxicity and imaging experiments suggested that probe 1 is can be used to monitor hydrazine in live cells. Graphical Abstract Unlabelled Image Highlights • A new coumarin-based ratiometric fluorescent probe (1) was developed for N 2 H 4. • Probe 1 is highly selective and sensitive for N 2 H 4 with a detection limit of 34 nM. • Probe 1 displayed excellent water-solubility and biocompatibility. • Probe 1 was successfully utilized for the detection of intracellular N 2 H 4. [ABSTRACT FROM AUTHOR]

Abstract Metalloproteins are often a useful template for the design and development of peptide fluorescent probes. Herein, we report a novel and simple fluorescent probe L comprised of tetrapeptide and dansyl groups by the solid phase peptide synthesis (SPPS). As a multifunctional analytical probe, L exhibited a highly selective "turn-on" fluorescent response to zinc ions, and a selective "turn-off" fluorescent response to copper ions at an excitation wavelength of 330 nm. The high sensitivity of L was made possible photo-induced electron transfer (PET), and L exhibited very low detection limits for Zn2+ and Cu2+ of 4.9 nM and 15 nM in 100% aqueous solutions, respectively. Furthermore, L displayed very low biotoxicity and excellent cell permeability, and was successfully used for detection of Zn2+ and Cu2+ in living HeLa cells based on two different mechanisms. We believe that the probe L may have many potential applications in environmental and biological research. Graphical Abstract Unlabelled Image Highlights • A novel and simple fluorescent probe (L) was synthesized. • L exhibited exclusively selective to Zn2+ and Cu2+. • The detection limits of Zn2+ and Cu2+ were 4.9 nM and 15 nM respectively. • The reversibility process of Zn2+ and Cu2+ by L was confirmed by EDTA. • L could serve as a potential probe to detect Zn2+ and Cu2+ in living cells. [ABSTRACT FROM AUTHOR]

Abstract A novel fluorescent probe, phenolphthalein‑dialdehyde‑(2‑pyridyl) hydrazone (L), for sequentially detecting Al3+ and F− in almost 100% aqueous medium was successfully designed and synthesized. The probe offers two binding pockets for Al3+ to form a 1: 2 ligand/metal complex, leading to a significant fluorescence enhancement at 465 nm. Further, the in-situ formed L-Al complex acts as a secondary fluorescent chemosensor for F− by quenching the fluorescence of the complex with high selectivity. The detection limit for Al3+ and F− sensing is 2.28 nM and 0.13 μM, respectively, which are far below the World Health Organization (WHO) acceptable limits (7.41 μM for Al3+ ion and 79 μM for F−) in drinking water. The probe L was successfully applied to the detection of Al3+ and F− in cells using fluorescence microscopy. Graphical Abstract The new fluorescent probe L can be used for selective detection of Al3+ and F− in almost 100% aqueous medium and live cells. Unlabelled Image Highlights • A new fluorescent probe L was synthesized and characterized • L can be used for selective detection of Al3+ and F−. • L exhibits a fluorescence response in almost 100% aqueous medium and live cells. • The detection limit for Al3+ was as low as nano-molar level. • L was employed for imaging the Al3+ and F− in living biological cells. [ABSTRACT FROM AUTHOR]

We have successfully developed a new green-emitting H 2 S fluorescence probe employing a 2,4-dinitrophenyl ether moiety as the sensing group based on 3′-formyl-4′-hydroxybiphenyl-4-carbonitrile. This probe displayed a rapid (2 min), sensitive (the detection limit was 0.18 μM) and selective with a large Stokes shift (183 nm) in response to H 2 S, which was beneficial for fluorescence sensing and cell imaging studies. Moreover, this probe can qualitatively and quantitatively detect H 2 S with a good linearity (R 2  = 0.9991). Importantly, this probe had been used for the detection of H 2 S in living MDA-MB-231 cells with good performance. [ABSTRACT FROM AUTHOR]

Homocysteine (Hcy) and glutathione (GSH) play important roles in a variety of physiological and pathological processes. Abnormal levels of Hcy and GSH are related to various diseases. Fluorescent probes for detecting them with sensitive and selective are highly desirable. However, efficient discrimination of Hcy and GSH is still a challenge for their similar molecular structures and chemical properties. Herein, we report a naphthalimide and sulfonyl benzoxadiazole (SBD) based dual-selective fluorescent probe for Hcy and GSH over other amino acids. The probe exhibited weak fluorescence (Φ = 0.075, in DMSO) at 490 nm and fluorescence enhancement upon addition of GSH (1–20 μM) with a detection limit of 0.8 μM. The probe also exhibited ratiometric fluorescence responses for Hcy (fluorescence at 490 nm decreased and fluorescence at 552 nm increased). The fluorescence intensity ratio (I 552 /I 490 ) showed a good linear correlation with the Hcy concentrations in range of 3–20 μM and the detection limit was 0.1 μM. Moreover, this probe was successfully utilized for monitoring Hcy and GSH in living cells. [ABSTRACT FROM AUTHOR]

[Display omitted] • A dicyanoisophorone-based ICT fluorescent probe was prepared. • A strong yellow fluorescence enhancement after treatment by Hg2+. • The probe was applied to detect Hg2+ in water/food sample. Mercury ions are notoriously difficult to biodegradable, and its abnormal bioaccumulation in the human body through the food chain can cause various diseases. Therefore, the quantitative and real-time detection of Hg2+ is very extremely important. Herein, we have brilliant designed and synthesized (E)-O-(4-(2-(3-(dicyanomethylene)-5,5-dimethylcyclohex-1-en-1-yl)vinyl)phenyl) O-phenyl carbonothioate (ICM-Hg) as a selective fluorescent probe for Hg2+ detection in real samples and intracellular staining. ICM-Hg displayed high specificity toward Hg2+ by activating the intramolecular charge transfer (ICT) process, resulting in distinguished color change from colorless to bright yellow along with noticeable switch on yellow fluorescence emission. The fluorescent intensity of ICM-Hg at 585 nm shows a well linear relationship in the range of Hg2+ concentration (0–45 μM), and the detection of limit for Hg2+ is calculated to be 231 nM. Promisingly, ICM-Hg can efficiently detect Hg2+ in real samples including tap water, tea, shrimp, and crab with quantitative recovery as well as the intracellular fluorescence imaging. [ABSTRACT FROM AUTHOR]

[Display omitted] • Organic small molecule fluorescent probes for the specific recognition of Cys were designed and synthesised on the basis of nitrile biphenyls. • The detection of Cys by probe ZHJ-X was studied systematically. • Probe ZHJ-X can be used for specific recognition of Cys with more rapid and efficient detection ability, the corresponding detection limit could be as low as 3.8 × 10-6 M. • The probe has also been successfully applied to detection of target ions in MCF-7 cells、HL60 cells and zebrafish. Cys play an important physiological role in the human body. Abnormal Cys concentration can cause many diseases. Therefore, it is of great significance to detect Cys with high selectivity and sensitivity in vivo. Because homocysteine (Hcy) and glutathione (GSH) have similar reactivity and structure to cysteine, few fluorescent probes have been reported to be specific and efficient for cysteine. In this study, we designed and synthesized an organic small molecule fluorescent probe ZHJ-X based on cyanobiphenyl, which can be used to specifically recognize cysteine. The probe ZHJ-X exhibits specific selectivity for cysteine, high sensitivity, short reaction response time, good anti-interference ability, and has a low detection limit of 3.8 × 10-6 M. The probe ZHJ-X was successfully applied to the visualization of Cys in living cells and had great application prospects in cell imaging and detection. [ABSTRACT FROM AUTHOR]

[Display omitted] • Near-infrared "turn-on" H 2 S fluorescence probe NIR-H 2 S constructed by novel fluorophore dye NIR-OH , excited at 686 nm and emitted at 736 nm. • Easily acquisitive (3 steps synthesis), Naked-eye visible colour change (from purple to green), high selectivity, high sensitivity (0.353 μM H 2 S), satisfactory response and low cytotoxicity. • Successfully imaged exogenous and endogenous H 2 S in living cells. Hydrogen sulfide (H 2 S) plays a substantial role as a messenger in the physiological and pathological processes of many diseases. Recently, the fluorescence probe of H 2 S based on organic dye has attracted great attention. However, the emission of many probes is in the UV–vis region (400–600 nm), so it has the disadvantages of shallow tissue penetration and more vulnerable to spontaneous fluorescence interference. Although several H 2 S probes have been developed that emit more than 650 nm, there is a complex structure difficult to synthesize or unstable in storage. Aimed at simply structural and easily synthesized H 2 S fluorescent probes with emission wavelength more than 650 nm, a novel near-infrared (NIR) probe (NIR-H 2 S) here was rationally designed with 4-(2-carboxyphenyl)-7-(diethylamino)-2-(4-hydroxystyryl)chromenylium (NIR-OH) as a fluorescent dye and 2,4-dinitrophenyl moiety as a recognition group. Addition of H 2 S, the "turn-on" NIR fluorescence response at 736 nm of NIR-H 2 S was displayed, accompanied by a visual colour change from purple to green when excited at 686 nm. As an easily acquisitive H 2 S probe, NIR-H 2 S has been successfully applied to cell imaging for H 2 S detection with the advantages such as long fluorescence emission, low toxicity, high sensitivity and strong selectivity. [ABSTRACT FROM AUTHOR]

A benzothiazole-based turn-on fluorescent probe with a large Stokes shift (190 nm) has been developed for hypochlorous acid detection. The probe displays prompt fluorescence response for HClO with excellent selectivity over other reactive oxygen species as well as a low detection limit of 0.08 μM. The sensing mechanism involves the HClO-induced specific oxidation of oxime moiety of the probe to nitrile oxide, which was confirmed by HPLC-MS technique. Furthermore, imaging studies demonstrated that the probe is cell permeable and can be applied to detect HClO in living cells. [ABSTRACT FROM AUTHOR]

A novel dicyanoisophorone based fluorescent probe HP was developed to detect hydrazine. Upon the addition of hydrazine, probe HP displayed turn-on fluorescence in the red region with a large Stokes shift (180 nm). This probe exhibited high selectivity and high sensitivity to hydrazine in solution. The detection limit of HP was found to be 3.26 ppb, which was lower than the threshold limit value set by USEPA (10 ppb). Moreover, the probe was successfully applied to detect hydrazine in different water samples and living cells. [ABSTRACT FROM AUTHOR]

A new aluminum ion fluorescent probe (4-(diethylamino)-2-hydroxybenzylidene)isoquinoline-1-carbohydrazide (HL 1 ) has been conveniently synthesized and characterized. HL 1 exhibited a highly selective and pronounced enhancement for Al 3+ in the fluorescence emission over other common cations by forming a 2:1 complex, with a recognition mechanism based on excited-state intramolecular proton transfer (ESIPT) and intramolecular charge transfer (ICT). The strong fluorescent emission can be observed even at ppm level concentration of the probe in the presence of Al 3+ with 41 fold intensity enhancement at 545 nm. HL 1 displays good linear relationship with Al 3+ in the low concentration and the limit of detection is 8.08 × 10 −8  mol/L. Similar molecules with different substituents on salicylaldehyde phenyl ring were synthesized for studying the structure-activity relationship. Density-functional theory (DFT) calculations are in agreement with the proposed mechanism. It is confirmed that HL 1 could be used to detect Al 3+ ions in real sample by fluorescence spectrometry and Al 3+ ions in cells by bioimaging. [ABSTRACT FROM AUTHOR]

A highly selective copper ions fluorescent probe based on the coumarin-type Schiff base derivative 1 (probe) was produced by condensation reaction between coumarin carbohydrazide and 1H-indazole-3-carbaldehyde. The UV–vis spectroscopy showed that the maximum absorption peak of compound 1 appeared at 439 nm. In the presence of Cu 2 + ions, the maximum peak decreased remarkably compared with other physiological important metal ions and a new absorption peak at 500 nm appeared. The job's plot experiments showed that complexes of 1:2 binding mode were formed in CH 3 CN:HEPES (3:2, v/v) solution. Compound 1 exhibited a strong blue fluorescence. Upon addition of copper ions, the fluorescence gradually decreased and reached a plateau with the fluorescence quenching rate up to 98.73%. The detection limit for Cu 2 + ions was estimated to 0.384 ppm. Fluorescent microscopy experiments demonstrated that probe 1 had potential to be used to investigate biological processes involving Cu 2 + ions within living cells. [ABSTRACT FROM AUTHOR]

A coumarin-based sensor C1 , namely 3-acetoacetylcoumarin was designed, synthesized and applied for hydrazine detection. Hydrazinolysis of the chemosensor gives a fluorescent coumarin-pyrazole product C1 − N 2 H 4 [3-(3-methyl-1H-pyrazol-5-yl)coumarin], and thus resulting in a prominent fluorescence off-on response toward hydrazine under physiological conditions. The probe is highly selective toward hydrazine over cations, anions and other biologically/environmentally abundant analytes. The detection limit of the probe is 3.2 ppb. The sensing mechanism was supported by 1 H NMR, IR, MS and DFT calculation. The application of the fluorescent probe in monitoring intracellular hydrazine in glioma cell line U251 was also demonstrated. [ABSTRACT FROM AUTHOR]

A novel compound TPI-H containing triphenylimidazole chromophore is synthesized and employed as fluorescent probe for sequential detection of Cu 2 + and S 2 − . With three binding sites in its molecular structure, TPI-H exhibits highly selective binding towards Cu 2 + and results in an apparent fluorescence “on-off” behavior. Fluorescence intensity is linear with the Cu 2 + concentration, and the detection limit can be down to 8.7 nM. Furthermore, the in-situ generated ensemble between TPI-H and Cu 2 + (TPI-H-Cu(II)) can be used to detect S 2 − with a low detection limit of 15.6 nM through Cu 2 + displacement method. In addition, the potential utility of the probe for the detection of Cu 2 + and further S 2 − in biological system is investigated by cell imaging. [ABSTRACT FROM AUTHOR]

A highly selective long-wavelength turn-on fluorescent probe has been developed for the detection of N 2 H 4 . The probe was prepared by conjugation the tricyanofuran-based D-π-A system with a recognizing moiety of acetyl group. In the presence of N 2 H 4 , the probe can be effectively hydrazinolysized and produce a turn-on fluorescent emission at 610 nm as well as a large red-shift in the absorption spectrum corresponding to a color change from yellow to blue. The sensing mechanism was confirmed by HPLC, MS, UV-vis, emission spectroscopic and theoretical calculation studies. The probe displayed high selectivity and sensitivity for N 2 H 4 with a LOD (limit of detection) of 0.16 μM. Moreover, the probe was successfully utilized for the detection of hydrazine in living cells. [ABSTRACT FROM AUTHOR]

[Display omitted] • The turn-on fluorescent probe CO-H1 is well located in mitochondria of cells. • Probe CO-H1 shows high selectivity and sensitivity for CO. • Monitoring the variation of both exogenous and endogenous mitochondrial CO in living cells was successfully performed. Carbon monoxide (CO), a vital gasotransmitter, plays critical functions in many physiological processes. Mitochondrial CO is closely related to mitochondrial respiration, thus the detection and imaging of mitochondrial CO in living cells is very important and has attracted much attention recently. In this paper, we developed a hemicyanine-based off–on fluorescent probe, CO-H1, which was used for monitoring endogenous mitochondrial CO levels in living cells. After reacted with CO in the presence of PdCl 2 , the fluorescence of CO-H1 was enhanced notably, accompanied by a significant red shift of absorption. CO-H1 exhibits low cytotoxicity, high sensitivity (detection limit of 0.048 μM), and good selectivity for CO. When incubated with living cells, probe CO-H1 mainly entered the mitochondria. CO-H1 was successfully applied to imaging the exogenous/endogenous mitochondrial CO in living cells, suggesting its potential application for further studying the biological functions of mitochondrial CO in living cells. [ABSTRACT FROM AUTHOR]

[Display omitted] • LL2 is a novel multifunctional fluorescent probe, which can work as a colorimetric probe for Cu2+ also selectively recognize Cu2+ via ratiometric fluorescence signal. • The probe LL2 has been successfully applied to live HepG2 cells ratiometric fluorescence monitoring and the visual detection of test paper, which has a good practical application value. • The probe LL2 can target both lipid droplets and lysosomes. A novel multifunctional fluorescent probe LL2 was prepared via a one-step condensation reaction between 3-formyl- N -butylcarbazole and 2-Hydroxy-1-naphthylhydrazone. LL2 can work as a colorimetric probe for Cu2+, and can also selectively recognize Cu2+ via ratiometric fluorescence signal. After the addition of Cu2+, the probe LL2 responded rapidly within 5 s and reached stability within 30 s. In natural light, when Cu2+ were added to the solution, the color of probe LL2 changed from yellowish to colorless, while there was a discernible fluorescence changed from green to blue under a 365 nm UV lamp. The ratiometric fluorescence intensity (F 449 /F 510) showed a good linear relationship (R2 = 0.9902) with Cu2+ concentration in the concentration range of 0–5 μmol/L, and the minimum detection limit was 1.96 μM. Cell imaging experiments showed that LL2 could capture fluorescence signals in the green and blue channels of HepG2 cells through fluorescence confocal microscope, and successfully recognize exogenous Cu2+ in HepG2 cells. In addition, fluorescence co-localization experiments showed that LL2 could target both lipid droplets and lysosomes. Meanwhile, LL2 could be applied to filter paper strip assay and detection of Cu2+ in actual water samples. These results indicated that probe LL2 has a good capability for monitoring Cu2+ in environment and living cells. [ABSTRACT FROM AUTHOR]

[Display omitted] • (Z)-4-(1-cyano-2-(7-hydroxynaphthalen-2-yl)vinyl)-1-methylpyridin-1-ium iodide (Mito-NPH) used pyridine salt as the receptor and naphthalenic unit as the donor for specific recognition of SO 2 derivatives based on intramolecular charge transfer (ICT) process. • Mito-NPH exhibits ultrafast response rate (within 10 s) and high selectivity toward SO 2 derivatives. • Mito-NPH can be successfully applied for imaging of mitochondrial endogenous SO 2 derivatives in live cells. Sulfur dioxide (SO 2) is a one of reactive sulfur species (RSS) that plays significant roles in many physiological processes. While abnormal levels of SO 2 in mitochondria have been related to various diseases. Hence, developing suitable fluorescent probe for monitoring SO 2 is significant in living organisms. In this research, we designed and synthesized a mitochondrial-target probe Mito-NPH featuring the graft of a strong electron-withdrawing 4-pyridiniumylacrylonitrile unit to an electron-donating naphthalenic unit that intramolecular charge transfer (ICT) process happened. The probe Mito-NPH underwent a nucleophilic addition of HSO 3 −/SO 3 2−to give fluorescent emission signal change from red to blue and exhibited specific response toward HSO 3 −/SO 3 2−over other analytes. Moreover, Mito-NPH showed ultrafast response rate (within 10 s) for HSO 3 −. Importantly, cell imaging results demonstrated that the probe can sense endogenous SO 2 in mitochondria. [ABSTRACT FROM AUTHOR]

One-pot synthesis of N -CDs was applied as a highly efficient "ON-OFF-ON" fluorescent probe for the rapid detection of CAL and l -Arg/ l -Lys in living cells. As a consequence, these N -CDs as a powerful analysis tool displayed more prominent and influential ability in real-time monitoring CAL and l -Arg/ l -Lys, and might offer a new opportunity for exploring the physiological and pathological processes of amino acid metabolism diseases. [Display omitted] • The nitrogen-doped carbon dots (N -CDs) were synthesized via a simple one-step hydrothermal method. • These CDs could rapidly and selectively detect CAL and l -Arg/ l -Lys with the detection limits as low as 58 nM, 18 nM/16 nM, respectively. • The N -CDs as a fluorescent probe displayed low toxicity and were suitable for sensing CAL and l -Arg/ l -Lys in living cells. The disorder of amino acid metabolism and the abuse of small molecule drugs pose serious threats to public health. However, due to the limitations of existing detection technologies in sensing cinnamaldehyde (CAL) and l -Arginine/ l -Lysine (l -Arg/ l -Lys), there is an urgent need to develop new sensing strategies to meet the severe challenges currently facing. Herein, nitrogen-doped carbon dots (N -CDs) were developed using a simple one-pot hydrothermal carbonization method. These N -CDs exhibited numerous distinctive characteristics such as excellent photoluminescence, high water dispersibility, favorable biocompatibility, and superior chemical inertness. Strikingly, the as-prepared CDs as a highly efficient fluorescent probe possessed significant sensitivity and selectivity toward CAL and l -Arg/ l -Lys over other analytes with a low detection limit of 58 nM and 16 nM/18 nM, respectively. The fluorescence of N -CDs could be quenched by CAL through an electron transfer process. Then, the strong electrostatic interaction between l -Arg/ l -Lys and N -CDs induced the efficient fluorescence recovery. More importantly, the outstanding biosafety and excellent analyte-responsive fluorescence characteristics of N -CDs have also been verified in living cells as well as in serum and urine. Overall, the N -CDs had a wide application prospect in the diagnosis of amino acid metabolic diseases and small molecule drug sensing. [ABSTRACT FROM AUTHOR]

One-pot synthesis of N -CDs was applied as a highly efficient "ON-OFF-ON" fluorescent probe for the rapid detection of CAL and l -Arg/ l -Lys in living cells. As a consequence, these N -CDs as a powerful analysis tool displayed more prominent and influential ability in real-time monitoring CAL and l -Arg/ l -Lys, and might offer a new opportunity for exploring the physiological and pathological processes of amino acid metabolism diseases. [Display omitted] • The nitrogen-doped carbon dots (N -CDs) were synthesized via a simple one-step hydrothermal method. • These CDs could rapidly and selectively detect CAL and l -Arg/ l -Lys with the detection limits as low as 58 nM, 18 nM/16 nM, respectively. • The N -CDs as a fluorescent probe displayed low toxicity and were suitable for sensing CAL and l -Arg/ l -Lys in living cells. The disorder of amino acid metabolism and the abuse of small molecule drugs pose serious threats to public health. However, due to the limitations of existing detection technologies in sensing cinnamaldehyde (CAL) and l -Arginine/ l -Lysine (l -Arg/ l -Lys), there is an urgent need to develop new sensing strategies to meet the severe challenges currently facing. Herein, nitrogen-doped carbon dots (N -CDs) were developed using a simple one-pot hydrothermal carbonization method. These N -CDs exhibited numerous distinctive characteristics such as excellent photoluminescence, high water dispersibility, favorable biocompatibility, and superior chemical inertness. Strikingly, the as-prepared CDs as a highly efficient fluorescent probe possessed significant sensitivity and selectivity toward CAL and l -Arg/ l -Lys over other analytes with a low detection limit of 58 nM and 16 nM/18 nM, respectively. The fluorescence of N -CDs could be quenched by CAL through an electron transfer process. Then, the strong electrostatic interaction between l -Arg/ l -Lys and N -CDs induced the efficient fluorescence recovery. More importantly, the outstanding biosafety and excellent analyte-responsive fluorescence characteristics of N -CDs have also been verified in living cells as well as in serum and urine. Overall, the N -CDs had a wide application prospect in the diagnosis of amino acid metabolic diseases and small molecule drug sensing. [ABSTRACT FROM AUTHOR]

[Display omitted] • A series of (E)-2-styrylanthracene-9,10-dione derivatives were synthesized. • The structure-photophysical property relationship was preliminarily investigated. • The ICT characteristic was analyzed through spectroscopy and DFT calculations. • Compound TZ07 proved to be an excellent green mitochondrial-targeting probe. • The mechanism of TZ07 targeting mitochondria was proved to be related to MCI. Our previous work firstly reported that (E)-2-styrylanthracene-9,10-dione is a novel fluorescent core (EK01) with the ability of specific mitochondria imaging. In this effort, we mainly focused our attention on the structure-photophysical property relationship and application in cells imaging of this new fluorescent chemotype. A series of the structural derivatives (TZ series) were designed and synthesized by introducing some substituents onto the 2-styryl moiety. The structure-photophysical property relationship analysis suggested that TZ03 is an excellent fluorescent molecular building block with the property of fluorescent "turn-on" effect after the modification of acylation, and TZ07 is an excellent fluorescent dye with a series of advantages such as high fluorescence intensity (F max = 4049.0 in CH 2 Cl 2 , 25.80 μM), moderate molar extinction coefficients (3.77 × 103-5.93 × 103 mol−1∙L∙cm−1), strong fluorescence quantum yield (Φ max = 0.739 in CH 2 Cl 2), large Stokes shift (99.0 nm-161.8 nm) and well biological tolerance. As a classical D-π-A structure, the ICT characteristic of TZ07 was analyzed through spectroscopy verification and DFT calculations. Furthermore, optimized compound TZ07 was successfully applied in the living cells imaging with the excellent selectivity to mitochondria in a green fluorescent form. It was also suggested that the mechanism of TZ07 targeting mitochondria is independent of mitochondrial membrane potential, but probably related to the mitochondrial complex I. These findings may provide some insights into the development of novel mitochondria-targeted fluorescent probes. [ABSTRACT FROM AUTHOR]

[Display omitted] • A Golgi-targetable fluorescent probe for hypochlorous acid has been reported. • The probe displays high sensitivity and high selectivity for HOCl. • The probe can be used for detection of HOCl within the Golgi apparatus of living cells. The Golgi apparatus (GA) is a vital organelle in biological systems and excess reactive oxygen species (ROS) is produced during stress in the Golgi apparatus. Hypochlorous acid (HOCl) is a significant reactive oxygen species and has strong oxidative and antibacterial activity, but excessive secretion of hypochlorous acid can affect Golgi structure or function abnormally, it will lead to a series of diseases including Alzheimer's disease, neurodegenerative diseases, autoimmune diseases, and Parkinson's disease. In present work, a novel fluorescent probe for Golgi localization utilizing naphthalimide derivatives was constructed to detect hypochlorous acid. The fluorescent probe used a derivatived 1,8-naphthalimide as the emitting fluorescence group, phenylsulfonamide as the localization group and dimethylthiocarbamate as the sensing unit. When HOCl was absent, the intramolecular charge transfer (ICT) process of the developed probe was hindered and the probe exhibited a weak fluorescence. When HOCl was present, the ICT process occurred and the probe showed strong green fluorescence. When the HOCl concentration was altered from 5.0 × 10−7 to 1.0 × 10−5 mol·L-1, the fluorescence intensity of the probe well linearly correlated with the HOCl concentration. The detection limit of 5.7 × 10−8 mol·L-1 was obtained for HOCl. The HOCl fluorescent probe possessed a rapid reaction time, a high selectivity and a broad working pH scope. In addition, the probe possessed good biocompatibility and had been magnificently employed to image Golgi HOCl in Hela cells. These characteristics of the probe demonstrated its ability to be used for sensing endogenous and exogenous hypochlorous acids within the Golgi apparatus of living 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]