Search

The development of fluorescent probes enabling to distinguish Cys, Hcy and GSH has always been a considerable challenge, in particular the distinction of Hcy and other two biothiols, because Hcy has a very similar structure with Cys and a relatively lower concentration in living organisms. In this work, a special o-dialdehyde fluorescent probe, quinoline-2,3-dicarboxaldehyde (QDA), has been synthesized and demonstrated superior performance in differentiating detection of Hcy and GSH, which is different from the previous reported o-dialdehyde probes specifically detecting GSH. Furthermore, the probe can selectively distinguish Hcy and GSH from different signal channels in living cells and zebrafish, meaning it has great potential in biological applications. This finding will provide a novel idea for the design of fluorescent probes to distinguish biothiols.

Intracellular pH has a significant influence on cell metabolism and various physiological activities. Therefore, there is an urgent need for a chemical sensor with excellent performance for intracellular pH-sensitive detection, which is extremely helpful for further understanding of related physiological and pathological processes. In this work, a ratiometric fluorescent probe, (1-(pyren-1-yl)-3-(pyridine-3-yl)-acrylketone (PPAK), was synthesized by the condensation reaction of 1-acetylpyrene and 3-pyridinecarboxaldehyde. PPAK has been used to detect extremely acidic and extremely alkaline pH in aqueous solutions. The recognition mechanism of PPAK depended on the protonation of the pyridine groups under acidic conditions and the attack of hydroxyl toward the carbonyl group to break down the conjugated structure under alkaline conditions, respectively. PPAK also exhibited favorable properties including outstanding photostability, excellent selectivity, rapid response and large stokes shift (166 nm). Finally, the results of E. coli cells imaging demonstrated its applicability in monitoring the pH changes in living cells.

Cysteine (Cys) is an essential amino acid in organism, which is transformed from methionine in vivo and participates in protein synthesis and cell redox process. Therefore, the detection of Cys is of great significance. In this work, a novel fluorescent probe, (E)-3-(2-chloroquinolin-3-yl)-1-(pyren-3-yl) prop-2-en-1-one (PAQ) was designed and synthesized to specifically detect Cys. The response mechanism of the reaction between PAQ and Cys was due to the addition reaction of Cys to α,β-unsaturated ketone of PAQ. Interestingly, the addition of Cys induced significant fluorescence intensity enhancement at 462 nm. PAQ exhibited favorable sensing properties towards Cys such as the low limit of detection (0.27 μM) and fast response speed (2 min). In addition, PAQ displayed high selectivity and anti-interference ability toward Cys among various analytes. Notably, PAQ has been successfully used to image exogenous and endogenous Cys in HeLa cells.

It is well known that sulfite (SO32−) plays an indispensable role in various physiological processes. Abnormal levels of SO32− can trigger a wide variety of diseases involving respiratory, nervous and cardiovascular systems. Hence, it is necessary to find an efficient approach for detection of SO32−. In this study, a pyrene derivative, (E)-4-(3-oxo-3-(pyren-1-yl)prop-1-en-1-yl)phenyl acrylate (PPA), was designed and synthesized for monitoring SO32−. The probe possessed simple synthetic steps, excellent anti-interference ability and specific response to SO32− in the presence of other substances. The reaction between PPA and SO32− was ascribed to Michael addition and the detection mechanism was confirmed by HRMS spectra analysis and FTIR analysis. Additionally, PPA responded linearly to detect SO32− within the rang of 0–100 μM. The limit of detection was calculated as low as 0.17 μM in accordance with the recommendation of IUPAC (CDL =3sb/m). Notably, PPA was further applied in biological imaging in HepG2 cells, which provided a possibility to monitor SO32− in vivo.

Reactive sulfur species (RSS) play pivotal roles in various pathological and physiological processes. There exists an intricate relevance in generation and metabolism among these substances. Although they are nucleophilic, there are still some differences in their reactivity. There are many methods to detect them by using reactive fluorescent probes, but the systematic study of their reactivity is still lacking. In our study, we designed a multiple reaction site fluorescent probe based on benzene conjugated benzopyrylium and NBD. The study revealed that besides both biothiols and hydrogen sulfide, sulfur dioxide (SO2) can cleave the ether bond. There are two reaction forms for GSH with low reactivity: cutting the ether bond and adding the conjugated double bond of benzopyrylium. Nevertheless, Cys/Hcy with higher activity can further rearrange with NBD after cutting the ether bond. In addition, SO2 can not only cleave the ether bond, but also continue to add the conjugated double bond of benzopyrylium. The above processes lead to multicolor emission of the probe, thus realizing the characteristic analysis of different sulfides. Thus the probe can be used for the detection of sulfide in mitochondria, and further for the imaging of sulfide in cells and zebrafish. This effective analysis method will provide a broad application prospect for practical applications.

Biological thiols (Cys, Hcy and GSH) are crucial biomolecules in living cells and play indispensable roles in maintaining the redox homeostasis of organisms. But due to their similar molecular structure, the development of effective tools for distinguishing two or three of them remains a great difficulty. Herein, we constructed a sensitive sensor (CB) by connecting the bifunctional fluorescent reagent with coumarin derivatives for simultaneous recognition of these three thiols through different pathways. Free CB had no fluorescence; however, with gradual addition of thiols, the chlorine unit was replaced by sulfhydryl. Furthermore, the intramolecular rearrangement occurred between the amino and sulfhydryl groups of Cys/Hcy and yellow fluorescence was observed at 570 nm. However, GSH with a large structure could not undergo intramolecular rearrangement, and green fluorescence was excited at 505 nm. In this way, Cys/Hcy and GSH can be detected distinctively. Under dual excitation wavelengths, CB exhibited high selectivity and fast response to the three thiols. Furthermore, CB was successfully applied to imaging endogenous and exogenous thiols in living cells and zebrafish, providing us with a reliable tool for thiols recognition.

We report herein a caged luciferin probe Cy-Hy as a sequentially activated probe to selectively and sensitively sense l-Cys and H2O2, utilizing the present probe, the cellular excess l-Cys induced H2O2 up-regulation was observed for the first time in the living MDA-MB-231 cells.

An efficient, CO2-tuned and highly selective C–O bond cleavage of N-methylated formanilides with NaBH4 has been achieved. Notably, when using N2 as reaction atmosphere, the reaction gave N-methylaniline as major product via C–N bond hydrogenolysis.

A palladium catalyzed desulfurative coupling of allylthioethers with organoboronic acids under mild reaction conditions is described. The reaction exhibits high chemoselectivity and good functional group tolerance, allowing the synthesis of a wide range of α-branched enones. In addition, this approach enables a new retrosynthetic disconnection to multi-functionalised allylic molecules via selective cleavage of the C–S bond, thus providing a complementary allylation protocol to Tsuji–Trost reactions.

Biosynthesis is a necessary process to maintain life. In recent years, research has fully shown that three kinds of biothiols (Cys, Hcy, GSH) mainly play the role in oxidative stress and maintaining cell homeostasis in cells, and that abnormal concentrations will lead to the occurrence of cardiovascular diseases, cancers, etc. Various fluorescent probes have shown unprecedented advantages in detecting their concentrations and studying their biological functions. As a matter of fact, these three kinds of biothiols are generated in the process of biosynthesis in vivo. It is of great significance to understand their biosynthetic pathways and elucidate their synthetic relationships. In this work, to α,β-unsaturated ketones conjugated ethylenediamine coumarin and pyrandione was introduced boron fluoride and, through its strong electron deficiency effect, afforded a molecule having near-infrared emission and regulated the rigidity of molecules. At the same time, the conjugated double bond is used to respond to molecular rigidity. The rapid response of the probe to biothiols and the slow dissociation aggregation of the probe itself through the response environment could monitor the absence of biothiols in cells. In addition, based on the difference in sensitivity of response of Cys and GSH to the probe, this work studied the interaction between biosynthetic pathways of Cys and GSH in cells through enzyme inhibition for the first time. The relationship of restriction and regulation of biosynthesis in vivo was revealed.

Fischer-Tropsch (F-T) process is an important synthesis route to acquire clean liquid fuels through modern coal chemical industry, which converts syngas (CO and H2) into hydrocarbon, and also generates oxygenates discharged as the F-T waste-water. These oxygen-containing compounds in F-T waste-water have the similar molecular weight and some are even isomers of each other. Hence, it is necessary to develop rapid and efficient analysis tools to obtain identification and quantitative information of the F-T waste-water. The pure shift NMR techniques provided only chemical shift information in one-dimension 1H NMR spectra, without homonuclear JH-H coupling. In this work, we tested and compared three pure shift NMR techniques (including Zangger-Sterk, PSYCHE and TSE-PSYCHE methods) in the analysis of two F-T waste-water model mixtures, genuine waste-water and two alcohol isomer mixtures. The results show that JH-H coupling multiplicities are collapsed into singlets corresponding to individual chemically distinct protons of the compound. For some severely overlapped signals in the pure shift NMR spectra, the chemical shift selective filters with TOCSY (CSSF-TOCSY) experiments were conducted to assist the signal assignment. Thus, pure shift NMR approaches can identify most signals of components, and CSSF-TOCSY can extract the signal of a specific compound. The combination of these two NMR techniques offers a powerful tool to analyze the F-T waste-water or other complex mixtures including isomer mixtures.

Redox balance is a necessary guarantee to maintain the normal physiological activities of organisms. Cysteine (Cys), a critical biological thiol, has the effect of maintaining redox balance in the body. The concentration of intracellular Cys is abnormal under redox imbalance, thereby resulting in multiple diseases. Additionally, studies have revealed that Cu

An AB-type monomer based on a pillar[5]arene host and an imidazolium salt guest was successfully synthesized through a facile way. This monomer can self-assemble into linear supramolecular polymers in chloroform. After the addition of silver ions, the imidazolium salt group coordinated with silver ions to crosslink the linear supramolecular polymers at their ends, resulting in the formation of supramolecular polymer networks. Meanwhile, after further adding iodide ions, the supramolecular polymer network changed back to the linear supramolecular polymer. As a result, the topological structure of the system can be reversibly tuned. Furthermore, this supramolecular polymer network can be applied to remove organic dyes in water, suggesting its great potential in the treatment of waste water.

Redox balance is the core of holding the good physiological state of the body. Cysteine (Cys) is one of the important biomolecules, which plays an indispensable role in maintaining the body's redox homeostasis. The redox of organisms is mainly the result of the dynamic balance between reactive oxygen species (ROS) and biological reducing agents (such as Cys). Fluorescent probes have the advantages of simple operation, good specificity and high sensitivity, and have become a common tool for bio-sensing in complex systems. In this article, we designed a probe NF-O-SBD that can specifically detect Cys. The chlorine atom of NF-O-SBD was easily substituted by sulfhydryl as a reaction site. After the formation of sulfur substitution products, intramolecular rearrangement occurred and fluorescent signal was emitted in the yellow channel at 550 nm. It can be seen from the spectroscopy experiment that the content of Hcy in organisms (15 μM) basically did not cause significant fluorescence changes, Therefore, based on the practical application in biology, we further used NF-O-SBD to visualize endogenous and exogenous Cys in HepG-2 cells and zebrafish. Simultaneously, we used Cu

Reactive sulfur species (RSS) play pivotal roles in various pathological and physiological processes. There exists an intricate relevance in generation and metabolism among these substances. Although they are nucleophilic, there are still some differences in their reactivity. There are many methods to detect them by using reactive fluorescent probes, but the systematic study of their reactivity is still lacking. In our study, we designed a multiple reaction site fluorescent probe based on benzene conjugated benzopyrylium and NBD. The study revealed that besides both biothiols and hydrogen sulfide, sulfur dioxide (SO

We report herein a caged luciferin probe Cy-Hy as a sequentially activated probe to selectively and sensitively sense

In this work, we synthesized an independent bi-reversible reaction sensor BPC for simultaneously detecting cysteine (Cys) and sulfur dioxide (SO2), showing multi-fluorescence signal modes due to the regulable FRET efficiency, and finally achieving real-time process visualization of Cys metabolizing into SO2 in subcellular organelles and tumors.

Herein, we report a straightforward, environmentally friendly, and controllable palladium/ligand catalytic system to enable reductive/oxidative Heck reactions of cyclic enones with thiophene or furan derivatives via C-H activation. The key to this tunable reaction is the appropriate intercepting thienyl-Pd(II)-enolate during the enolization process. Such a controllable and economic protocol would not only provide efficient methods to construct various value-added β-heteroarylated cyclic ketones/enones but also shed light on developing other conjugate addition reactions via C-H activation.

A new fluorescent probe, (E)-3-(9-ethyl-9H-carbazol-6-yl)-1-(2-hydroxy-5-methoxyphenyl)prop-2-en-1-one (Probe 1), was synthesized based on the carbazole fluorophore for detecting ClO−. The fluorescent probe exhibited specificity for ClO− in many analytes and excellent anti-interference ability during detection. In addition, the fluorescence intensity at 525 nm illustrated a good linear relationship with the concentration of ClO− in the range of 53.6–107.2 μM and the limit of detection was 0.30 μM. Furthermore, fluorescence imaging results confirmed that Probe 1 can be applied to monitor ClO− in HepG2 cells, which indicated that Probe 1 has large potential for monitoring ClO− in vivo.

The identification of thiols has become a research hotspot due to its role in biological systems. In this work, we simply constructed a turn-on fluorescent probe named 3-(5-bromopyridin-3-yl)-1-(pyren-1-yl) prop-2-en-1-one, that a combination of pyrene ring and substituted pyridine via the connection of α, β-unsaturated ketone. Cys can destroy the space effect by Michael addition reaction, which makes the fluorescence intensity changes. Furthermore, the probe featured excellent selectivity and high sensitivity (the detection limit was 0.52 μM) by addition of Cys. Moreover, this probe suggested a potential for imaging in vivo owing to the successful imaging of the probe in HepG2 cells, zebrafish, and Arabidopsis thaliana.

Human centrin 2 (HsCen2) is a member of the EF-hand protein that plays a critical role in the centrosome duplication and separation during cell division. Reversible protein phosphorylation is an important regulatory mechanism for centrin. To obtain insight into the structural basis for the functional effects of phosphorylation, it was verified that the serine residue at position 170 of HsCen2 can be phosphorylated by protein kinase A (PKA) using 31P NMR spectroscopy. While the protein was phosphorylated, the extents of α-helix and the exposed hydrophobic surfaces on HsCen2 were decreased significantly. In the present paper, we reported the regulation and control of peptide p22-XPC binding with HsCen2 by isothermal titration calorimetry (ITC) and spectra. After being phosphorylated, the affinity of p22-XPC with HsCen2 was weakened almost 2 orders of magnitudes. And removing calcium ions from the system, no significant binding between them has been observed. Their binding was reversible. Functions of XPC may be double-regulated and controlled by calcium ions as well as phosphorylation. These results are of significance for understanding the relationship between PTM and metal regulation.

The new carbazole-based fluorescent probe CA-1 was designed and synthesized for the high selective detection of H2S based on HS− facilitated sulfur pyran resulting in UV–Vis and fluorescent spectra changes. At the same time, the probe showed good sensitivity to the detection of H2S with a low detection limit of 0.16 μM. The detection process can be monitored by naked eye: with the addition of H2S, the probe system changed from yellow to pink. Importantly, the probe could be applied in monitoring H2S in HepG2 cells and Chlorella. These results indicate that CA-1 can be used as a promising fluorescent probe for the detection of H2S in situ.

Hydrogen sulfide (H2S) emerges as an important mediator of human physiology and pathology but remains difficult to study, so it is urgent to find a sensor with high selectivety and rapidly response to detect H2S. The detection mechanism of H2S is various, and the reduction of nitro has developed rapidly in recent years. However, the reported nitro-based H2S probes still have drawback such as slow response. In this work, we introduced isoxazole to strengthen the oxidizability of nitro group, resulted in the response time significantly reduced within 55 s. In addition, this probe could be used to detect and imaging exogenous/endogenous H2S in HepG-2 cells.

The reactive oxygen species (ROS) including hypochlorous acid (HOCl), on the one hand they can regulate physiological function in our living organisms, on the other hand abnormal concentration of ROS would induce a series of biomacromolecules damage and further endanger virtually all aspects of human health. Especially it can be directly related to cancer. Thus to elucidate and visualize their concentration is very imminent. Before many fluorescent probes were used to detect HOCl. In recent years, near-infrared or ratiometric fluorescent developed prosperously. The strategy of combining near-infrared and ratiometric fluorescent probe is overwhelming in the design of fluorescent probes. In this work, we successfully designed and obtained a near-infrared and ratiometric fluorescent probe with large stokes by reacting isophorone with coumarin, which can monitor HOCl high efficiently with quick response and low detection limit. In addition, cell imaging experiments show that the probe can identify endogenous and exogenous ClO− successfully, and nude mouse imaging experiments show that the probe can detect exogenous ClO−. It is possible that the probe can be applied in early clinical diagnosis.

An increasing number of scientists have focused on the methods to enhance the nonlinear optics (NLO) performance of classic candidates, by chemical design/synthesis or physical measure. In order to validate an innovative strategy to enhance NLO responses while keeping the intrinsic nature of its molecular hyperpolarizabilities through the assistance of point charge electric field, we investigate the efficiency on typical D-π-A molecular hyperpolarizabilities of 4-nitroaniline a couple of point electric charge (4-nitroaniline@Na+ & Cl− in our study), together with configuration distortion and uniform external electronic field. Our work shows that the most effective method to improve its molecular hyperpolarizability is the introduction of point electric charge among the three strategies, which is ˜ around 100 times of the value using external electronic field. Moreover, in our instance the increment of its NLO response can be achieved simply by the distance of a couple of ions. Hopefully, researches with controlling of point electric charge in theory will facilitate the development of NLO materials in experiment.

Baicalin, one of the main active constituents of the isolated root of Scutellaria baicalensis. It has many health-promoting properties. However, it is easy to be oxidized that impedes its application in the practical life. In this study, the inclusion complexes of baicalin with p-sulfonatocalix[n]arenes were studied by fluorescence spectroscopy, ultraviolet–visible spectroscopy (UV–vis), fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, and atomic force microscopy. The results showed that baicalin was able to form inclusion complexes with p-sulfonatocalix[n]arenes in a molar ratio of 1:1 and the association constants (K) were different at different pH. Meanwhile, the antioxidant ability and stability experiments of baicalin and the inclusion complexes were done. The experimental results indicated that both the stability and the antioxidant activity of baicalin significantly increased by the formation of inclusion complexes with p-sulfonatocalix[n]arenes.

It is very important to measure the pH in the cells because abnormal pH in the body can cause many neurological diseases. In this work, a simple emission fluorescent pH probe 2-(benzothiazol-2-yl)-1-((pyren-3-yl) methylene) hydrazine (BMH) was synthesized by connecting pyrene-1-carboxaldehyde and 2-hydrazinobenzothiazole. BMH displayed fluorescence emission characteristics in which the pKa was 3.49 and responded linearly to measure pH range from 4.70 to 3.16. Meanwhile, it possessed high fluorescence quantum yield (64.60%). Moreover, BMH exhibited good stability and highly selectivity which promotes its ability in analytical application and the detection limit of approach was 0.41 μΜ. Simultaneously, it was fully able to image pH fluctuations due to its cell membrane permeability, biocompatibility and no auto-fluorescence effects.

A new near-infrared ratiometric type fluorescent probe was prepared. 3-formyl BODIPY derivatives without substituent group in the 2, 6-position was obtained through DDQ oxidation reaction. Furthermore, it reacted with indole salt to produce probe. This probe bears indolium group as the recognition site and the 3-formyl-BODIPY as fluorophore. The specific detection of cyanide was conducted the nucleophilic attack of cyanide toward the indolium group of the probe, breaking the intramolecular charge transfer (ICT) effect and generating a ratio change in the fluorescence signal. The probe has high selectivity and sensitivity for cyanide. Moreover, cell experiments indicated this probe was benign to HepG-2 cells, and has the potential application in imaging CN− in living HepG-2 cells.

Sulfur dioxide (SO2) is the main air pollutant in the environment, causing great harm to human health. Abnormal SO2 levels are usually associated with some respiratory diseases, cardiovascular diseases, and neurological disorders (even brain cancer). Therefore, monitoring SO2 levels is helpful to better understand its special physiological and pathological role. Although many fluorescent probes for SO2 have been reported, many of them were not ideal for in vivo imaging due to the short emission wavelength. In this work, a near-infrared fluorescent probe NIR-BN with emission wavelength of 680 nm was constructed by conjugating the benzopyrylium moiety and 6-hydroxy-2-naphthaldehyde. NIR-BN had high selectivity and rapidity for SO2 detection. In addition, the detection limit of NIR-BN was relatively low, which can be used for the determination of sulfite in different sugar samples with high accuracy. Of course, due to the excellent spectral and structural properties of NIR-BN, we have applied NIR-BN to the detection of SO2 in biological systems.

Endogenous sulfur dioxide (SO2) is mainly produced by the enzymatic reaction of sulfur-containing amino acids in mitochondria, which has unique biological activity in inflammatory reaction, regulating blood pressure and maintaining the homeostasis of biological sulfur. It is more and more common to detect monitor SO2 levels by fluorescence probe. In recent years, the indolium hemicyanine skeleton based on the D-π-A structure has been widely used in the development of fluorescent sensors for the detection of SO2. However, subtle changes in the chemical structure of indolium may cause significant differences in SO2 sensing behavior. In this article, we designed and synthesized two probes with different lipophilicities to further study the relationship between the structure and optical properties of hemicyanine dyes. On the basis of previous studies, the structure of indolium hemicyanine skeleton was optimized by introducing –OH group, so that MC-1 and MC-2 had the best response to SO32- in pure PBS system. In addition, the lipophilicity of MC-2 was better than that of MC-1, which enabled it to respond quickly to SO32- and better target mitochondria for SO2 detection. Most importantly, the low detection limits of MC-1 and MC-2 conducive to the detection of endogenous SO2. This work provided an idea for developing SO2 fluorescent sensors with excellent water solubility and low detection limit.

Biological thiols are crucial small molecule amino acids widely existing in cells, which play indispensable roles in maintaining redox homeostasis of living systems. Owing to their abnormal levels have close relation with many diseases, thus, developing more convenient, rapid and practical in-vivo detection tools is imminent. Herein, a reversible coumarin-based probe (HNA) was successfully constructed through a simple two-step synthesis. HNA can detect Cys/Hcy with high response speed and desirable selectivity based on Michael addition recognition mechanism. Free HNA has an orange emission at 580 nm, but after addition of Cys/Hcy, the conjugated structure of probe HNA was destroyed by the attack of sulfhydryl, resulting in a new green emission at 507 nm. Further, HNA has been applied to monitor Cys/Hcy in HeLa cells and zebrafish. Notably, HNA has also been successfully applied for real-time tracing Cys levels changes in living cells and zebrafish during the imbalance in redox status caused by copper (II). This provides a new strategy for studying the process of oxidative stress in cells.

As the structural unit of natural products, chromene derivatives show a wide range of biological activity and pharmacological activity due to their unique photophysical and chemical properties. Ten years ago, our research group discovered the "thiol-chromene" click reaction, which achieved the selective detection of thiols through the change of the optical spectrum. Afterward, we attempted to develop various chromene-based fluorescent probes for imaging including near-infrared (NIR) probe, ratiometric probe, and multifunctional probe. However, how to integrate the fluorophore and reaction sites into the chromene-based skeleton remains challenging. In this work, we connected the chromene motif with the NIR fluorophore methylene blue utilizing a carbamate spacer to provide a new fluorescent probe (CM-NIR), which is triggered by thiols to open the pyran ring followed by attacking the carbamate by phenolate to releases the methylene blue. This novel cascade mechanism avoids the formation of para-quinone methides, which proved to be toxic to normal cells. CM-NIR also showed the specific imaging of thiols in living cells and mice. More importantly, the thiols level in drug-resistant cancer cells was found to be significantly higher than that in the corresponding cancer cell, which indicated that the thiols level may have an important role in cancer cells developing drug resistance.

In recent years, it has become a trend to employ organic molecular fluorescent probes with multireaction sites for the distinguishable detection and biological imaging of similar substances. However, the introduction of multireaction sites brought great challenges to organic synthesis, and at the same time, often destroyed the conjugated structure of the molecules, leading to an unsatisfactory fluorescence emission wavelength not conducive to practical application. As the eternal theme of life, metabolism goes on all the time. Metabolism is a series of ordered chemical reactions that occurs in the organism to maintain life. Chemical reactions in metabolism can be summarized as metabolic pathways. Simultaneous monitoring of different metabolic pathways of the same substance poses a lofty challenge to the probe. Here, we developed a new strategy: to construct new sites through the preliminary reactions between probes and some targets, which can be used to further distinguish among targets or detect their metabolites, so as to realize the simultaneous visualization tracer of multiple metabolic pathways. By intravenous injection, it revealed that the probe containing benzopyrylium ion can target tumors efficiently, and thiols are highly expressed in tumors compared to other tissues (heart, lung, kidney, liver, etc.). The consumption of thiols by the probe could not prevent tumor growth, suggesting that the tumor cure was not correlated with thiol concentration. The construction of new sites in the reaction process is a novel idea in the pursuit of multiple reaction sites, which will provide more effective tools for solving practical problems.

The excellent water solubility of hydrazine (N2H4) allows it to easily invade the human body through the skin and respiratory tract, thereby damaging human organs and the central nervous system. To realize the monitoring of N2H4 effectively, first, coumarin was used to construct an inner alicyclic ring as the reaction site, extending the conjugation and strengthening the rigidity of the probe Co-Hy to improve its luminescence performance and enhance its ability to resist acids and alkalis. Second, we introduced a carboxyl group at the ortho position of the inner alicyclic ring to improve the water solubility of Co-Hy, and its strong electron pulling effect increased the activity of the reaction site. Spectroscopy experiments showed that Co-Hy featured excellent water solubility, high pH resistance (pH 4–11), excellent selectivity, fast analysis speed (within 5 minutes), and a low detection limit toward N2H4 (69 nM, 2.2 ppb). In addition, test-strip, spray, and cell-imaging experiments confirmed the outstanding application potential of Co-Hy for convenient N2H4 analysis in a variety of environments.

It is well known that sulfite (SO

Herein, we report a palladium-catalyzed dehydrogenative cross-coupling of indoles with cyclic enones to give β-indolyl cyclic enones under mild and neutral reaction conditions. The key to the success is to explore a mild condition, which ensures the indole C-H activation and subsequent syn β-hydride elimination through rapid enolization isomerization of Pd(II)-enolate while suppressing other undesired side reactions. Synthetic utility has also been demonstrated in the flexible transformation of the coupling products to meta-phenols and benzo[a]carbazoles.

The role of hydrazine in production is not to be underestimated due to its strong reducibility. However, every coin has two sides. Hydrazine represents a great hazard to the environment, which cannot be ignored. Aiming to prevent harm to people or the environment, a new near-infrared fluorescent probe is presented. This probe is specifically designed to sense hydrazine vapor accumulated in an enclosed space and detect excessive hydrazine in water samples. It shows good selectivity and a turn-on effect, as well as a remarkable color change that can be distinguished by the naked eye. This effect has been utilized for quantitative detection in real water samples. Moreover, the color change of the probe adsorbed on filter paper can be observed by the naked eye to monitor the presence of hydrazine in the air in real time; this property of the probe is expected to be used for hydrazine detection in industrial environments.

Herein, we report a new benzothiazole-based azomethine receptor L as a reversible fluorescent sensor for the selective detection of Al3+ in buffered aqueous methanol (20 mM HEPES, pH = 6.0, 50% (v/v) CH3OH). The fluorescence enhancement response of L towards Al3+ along with a large blue shift (Δλ = ∼157 nm) may be attributed to the formation of the L–Al3+ complex, which results in the inhibition of excited state intramolecular proton transfer (ESIPT) and CN isomerisation as well as the chelation enhanced fluorescence (CHEF). The results of Job's plot and mass spectroscopic analysis support the 1 : :1 stoichiometry of the complex between L and Al3+ ions. The proposed complex structure was calculated by applying the DFT method. Furthermore, the applicability of the probe has been tested in BEL-7402 human hepatoma carcinoma cells under a fluorescence microscope, where turn-on, intense bluish green fluorescence was observed in the presence of Al3+ ions.

2-(1-Amino-2-anthraquinonyliminomethyl)phenol (L) was facilely prepared as a spectroscopic probe by one step condensation between 1,2-diaminoanthraquinone and salicylaldehyde. The complexation of Cu

A simple tailor-made water-soluble broadly emitting (500-650 nm) fluorescent probe 3-methyl-2-(N-ethylcarbazole-3vinyl)-benzothiazolium iodide (IECBT) for the selective and sensitive detection of multiple analytes, including CN

Detection of hypochlorite ions (ClO-) in the organisms is of great significance for finding effective treatments for inflammations and diseases. Recently, fluorescent probes have aroused wide public concern as one of the effective tools for detecting molecules and ions. Nevertheless, due to low sensitivity and poor biocompatibility, the effect of fluorescent probes for biological imaging is still not ideal. For this, we developed a novel ratiometric fluorescent probe, 7-(diethylamino)-3-((E)-3-(9-ethyl-9H-carbazol-3-yl)acryloyl)-2H-chromen-2-one (DCC), which could be used for colorimetric detection of ClO-. Study showed that, the detection mechanism of DCC is that probe can be rapidly oxidized to an enoic acid by ClO-, resulting in a series of changes in spectral properties. This mechanism was confirmed experimentally and verified by theoretical calculations. It is worth mentioning that DCC has not only been successfully applied to the detection of exogenous and endogenous OCl- in living cells, but also used for the detection of ClO- in zebrafish, and Arabidopsis.

Sulfur dioxide (SO2), as the main member of reactive sulfur species (RSS), it is mainly produced in mitochondria and involved in a variety of activities at the cellular level. Excessive inhalation of SO2 could cause respiratory tract damage, cardiovascular disease and even cancer. The mitochondrial and lysosomal as two important organelles, their interactions (fusion and contact) are important for maintaining eukaryotic homeostasis. Some study indicated that SO2 is active in the above interaction process. In this work, benzopyranium salt unit was constructed as fluorophore I, where O+ was the mitochondrial target site, and naphthalimide was linked to morpholine to construct fluorophore II, where morpholine was the lysosomal target group. Studies have shown that the probe has a good performance in targeting both mitochondria and lysosomes. And after the reaction with SO2, FRET was broken, resulting in red quenching, and green emitting, which made it can detect SO2 with a ratiometric response. Cells cultured with nystatin showed decreased red and green fluorescence increased, indicating that the autophagy of mitochondria produced SO2. In addition, synthesized control reagents (targeting lysosomes alone and responding to SO2) from no signal to gradually enhanced blue fluorescence, indicating that SO2 produced by mitochondria is transferred to lysosomes. What's more, it could monitor the changes of SO2 concentration under heat stroke. More importantly, it could quantitatively detect sulfite concentration in Yuba and crystal sugar.

For SO2, another Cys metabolite, to simultaneously distinguish SO2 over thiols are still a challenge. Now we have successfully synthesized a novel coumarin-based turn-on fluorescent probe that could detect distinguishingly sulfite/hydrogen sulfide over bio-thiols through whether or not acryloyl group is used as a self-immolative linker. The detection limit of probe 1 for Cys, Hcy, GSH, HS− and SO32- were found to be ∼0.23, 1.05, 0.46, 0.52 and 0.16 μM, respectively. Such a probe could detect H2S/SO32− and bio-thiols via two emission channels in B16 cells, and possessed the appropriate ability to detect exogenous H2S in living mouse. These specific responses demonstrate that probe 1 has the potential to reflect the metabolic process of cysteine.

Because of the high toxicity of hydrazine, the development of ultrasensitive fluorescent probes for hydrazine has been challenging. In this work, an ultrasensitive fluorescent probe based on o-phthalaldehyde has been exploited for hydrazine. The probe was designed based on creating an efficient fluorophore by incorporating hydrazine into o-phthalaldehyde framework via an intermolecular condensation-cyclization reaction. The probe could quickly detect hydrazine and displayed a high sensitivity for hydrazine with a LOD of 1.9 nM (0.06 ppb), which is far below the U.S. Environmental Protection Agency standard (10 ppb). Moreover, the probe was successfully applied to the detection of hydrazine in real water samples and hydrazine vapor.