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Excessive oxidative stress is the main cause of neurotransmitter metabolism disorder in the brain with depression. Lysosomal hypobromic acid (HOBr) is an important reactive oxygen species produced in oxidative stress. Its abnormal content can lead to macromolecular damage and neurodegenerative diseases. However, due to the high reactivity and low concentration of HOBr and the lack of in situ imaging methods, the role of HOBr in depression is not clear. Herein, based on the HOBr-initiated aromatic substitution of a tertiary amine, we developed a novel two-photon (TP) fluorescence probe (

Cancer, as a malignant tumor, seriously endangers human health. The study of cancer diagnosis and therapy has great practical significance. The development of theranostic agents has become a very important research topic. Nevertheless, some existing agents still have imperfections, such as complex structures and difficult syntheses. Therefore, it is urgent for researchers to develop simple novel theranostic agents. In this study, the precipitated fluorophore

A selective and ultra-sensitive colorimetric fluorescent probe was discovered to detect malononitrile in living cells and zebrafish.

A highly selective and sensitive water-soluble naphthalimide-based turn-on fluorescent probe was synthesized to detect Hg2+ in living cells and zebrafish.

Cancer is a serious threat to human health, and there is an urgent need to develop new treatment methods to overcome it. Organelle targeting therapy, as a highly effective and less toxic side effect treatment strategy, has great research significance and development prospects. Being an essential organelle, the Golgi apparatus plays a particularly major role in the growth of cancer cells. Acting as an indispensable and highly expressed antioxidant in cancer cells, glutathione (GSH) also contributes greatly during the Golgi oxidative stress. Therefore, it counts for much to track the changes of GSH concentration in Golgi for monitoring the occurrence and development of tumor cells, and exploring Golgi-targeted therapy is also extremely important for effective treatment of cancer. In this work, we designed and synthesized a simple Golgi-targeting fluorescent probe GT-GSH for accurately detecting GSH. The probe GT-GSH reacting with GSH decomposes toxic substances to Golgi, thereby killing cancer cells. At the same time, the ratiometric fluorescent probe can detect the concentration changes of GSH in Golgi stress with high sensitivity and selectivity in living cells. Therefore, such a GSH-responsive fluorescent probe with a Golgi-targeted therapy effect gives a new method for accurate treatment of cancer.

Periodontitis, one of the most common chronic inflammatory diseases, affects the quality of life. Osteogenesis makes an important role of the disease. There is a connection between hydrogen sulfide (H2S) and periodontitis, but according to the study has been published, the precise role of H2S in inflammation remains in doubt. The main reason of the lack of research is that H2S is an endogenous gasotransmitter, difficult to discern through testing. So, we synthesis a novel fluorescence probe which can detective H2S in vitro. By using the novel H2S fluorescence probe, we found that H2S changes in osteoblasts mainly by cystathionine-γ-lyase, and H2S increases under LPS stimulation. H2S could be a potential marker for diagnosis of inflammatory diseases of bone, and might help deeper studies of the changes of H2S level and promote the progression on the researches about pathogenesis of periodontitis.

The concentration of copper ions (Cu

A simple pyridine-based highly specific fluorescent probe was constructed to trace hypochlorous acid in lysosomes of living cells.

Nickel resources are abundant in the world, and the application of nickel in production and life is more and more extensive. However, excessive nickel entering the environment will not only cause environmental pollution but also seriously endanger plants, animals and human health. Nickel compounds are carcinogenic and have been classified as a class 1 carcinogen. Nickel mainly exists in the form of divalent ions in the environment. However, there are few simple and effective methods for the detection of nickel ions, and these methods still have certain limitations. At present, the mechanisms of nickel influence in organisms are also unclear. Therefore, we constructed a ratiometric fluorescent probe Ra-Ni, which can achieve its own self-calibration and avoid the interference of other factors, thereby realizing the specific identification of nickel ions. The probe can detect nickel ions sensitively with a detection limit as low as 26.2 nM and can respond in a short time (2 min), which proves the great potential of the probe in the detection of nickel ions. At the same time, Ra-Ni has also been successfully used for imaging nickel ions in living cells and zebrafish, providing an effective tool for the study of physiological and pathological processes. The detection effect of nickel ions in actual water sample is also satisfactory, which further demonstrates the practicability of Ra-Ni in environmental applications.

Considering that mercury ions (Hg

Mercury (Hg) is a heavy metal with high toxicity and easy migration; it can be enriched through the food chain, and cause serious threats to the natural environment and human health. So, the development of a method that can be used to detect mercury ions (Hg2+ ) in the environment, in cells, and in organisms is very important. Here, a new 7-hydroxycoumarin-derived carbonothioate-based probe (CC-Hg) was designed and synthesized for detection of Hg2+ . After addition of Hg2+ , a large fluorescence enhancement was observed due to the formation of 7-hydroxyl, which reinforced the intramolecular charge transfer process. The CC-Hg probe had good water solubility and selectivity. Moreover, the probe was able to detect Hg2+ quantitatively over the concentration range 0-2 μM and with a detection limit of 7.9 nM. Importantly, we successfully applied the probe to detect Hg2+ in water samples, in living cells, and in zebrafish. The experimental results demonstrated its potential value in practical applications.

We have synthesized a simple Golgi-targeting H2S fluorescent probe which can detect endogenous and exogenous H2S in cells and zebrafish. In addition, this probe provides a new chemical tool for the detailed study of generation pathways of H2S under Golgi stress response.

A novel Golgi-targeting Cys-specific fluorescent probe (Gol-Cys) was synthesized. Probe Gol-Cys is not only sufficiently sensitive to native Cys in living cells and zebrafish, but also can be used for monitoring the Cys level during Golgi stress.

When the cell environment changes or is stimulated, the Golgi apparatus will respond to the corresponding stress, through the opening of related pathways, the expression of corresponding substances can be promoted or inhibited to achieve the purpose of controlling cell redox homeostasis and reducing cytotoxicity. Intuitive analysis of the changes in the content of various substances in the process of stress has important guiding value for the further study of stress response, drug evaluation and clinical diagnosis. Therefore, for the Cys overexpressed during the oxidative stress of the Golgi apparatus, we developed a specific and sensitive fluorescent probe (Gol-NCS) to visually monitor the biologically important Cys in real time. The probe has low cytotoxicity and shows great potential in cell and zebrafish imaging, it can detect the changes of endogenous and exogenous cysteine. It is important to explore the synthetic pathway of Cys during Golgi stress by using the Golgi targeting performance of the probe Gol-NCS. It is confirmed by fluorescence imaging for the first time that the activity of CSE enzyme plays a decisive role in the formation of Cys. Therefore, probe Gol-NCS with excellent photochemical properties is expected to provide help for the research on the involvement of Cys in Golgi stress.

The outbreak and spread of Corona Virus Disease 2019 (COVID-19) has led to a significant increase in the consumption of sodium hypochlorite (NaOCl) disinfectants. NaOCl hydrolyzes to produce hypochlorous acid (HOCl) to kill viruses, which is a relatively efficient chlorine-based disinfectant commonly used in public disinfection. While people enjoy the convenience of NaOCl disinfection, excessive and indiscriminate use of it will affect the water environment and threaten human health. Importantly, HOCl is an indispensable reactive oxygen species (ROS) in human body. Whether its concentration is normal or not is closely related to human health. Excessive production of HOCl in the body contributes to some inflammatory diseases and even cancer. Also, we noticed that the concentration of ROS in cancer cells is about 10 times higher than that in normal cells. Herein, we developed a HOCl-activatable biotinylated dual-function fluorescent probe BTH. For this probe, we introduced biotin on the naphthalimide fluorophore, which increased the water solubility and enabled the probe to aggregate in cancer cells by targeting specific receptor overexpressed on the surface of cancer cell membrane. After reacting to HOCl, the p-aminophenylether moiety of this probe was oxidatively removed and the fluorescence of the probe was recovered. As expected, in the PBS solution with pH of 7.4, BTH could give full play to the performance of detecting HOCl, and it has made achievements in detecting the concentration of HOCl in actual water samples. Besides that, BTH had effectively distinguished between cancer cells and normal cells through a dual-function discrimination strategy, which used biotin to enrich the probe in cancer cells and reacted with overexpressed HOCl in cancer cells. Importantly, this dual-function discrimination strategy could obtain the precision detection of cancer cells, thereby offering assistance for improving the accuracy of early cancer diagnosis.

As a eukaryotic organelle, the Golgi apparatus plays an essential role in various physiological activities such as stress response. The Golgi stress response is an important physiological process of conferring cytoprotection by regulating the synthesis and metabolism of bioactive molecules. Therefore, the development of new suitable in situ analytical techniques for monitoring related small molecular substances in the stress reaction of the Golgi apparatus is very helpful for further study of the regulatory mechanism of the Golgi apparatus. Recent studies have shown that endogenous hydrogen sulfide (H2S) also possesses crucial bioregulatory and protective performances in the stress response. Therefore, the high-fidelity in situ mapping of H2S production under the Golgi stress response plays an important role not only in revealing cytoprotection functions of H2S in the stress response but also in further understanding the regulatory mechanism of the Golgi stress response. In this work, we designed a simple Golgi-targetable H2S fluorescent probe (Gol-H2S) that responds accurately and sensitively to H2S in the Golgi apparatus of living cells and zebrafish. On the basis of its superior bioimaging performances, probe Gol-H2S was successfully applied to the in situ visualization of H2S production under the Golgi stress response elicited by monensin, a specific-Golgi stressor. The related process of the Golgi stress response was validated by stimulation and inhibition experiments. These findings fully demonstrate that H2S is an alternative biomarker of the Golgi stress response. Moreover, probe Gol-H2S can also be used as a potential tool for disclosing the detailed H2S-cytoprotection mechanisms under the regulation of the Golgi stress response in related diseases.

In this work, by taking full advantage of the transformation of nitro group into amino moiety under the direct reduction of CO, a new metal-free colorimetric and near-infrared fluorescent probe NIR-CO for rapid and specific tracing of intracellular CO has been constructed, and it also become the first reaction-based near-infrared fluorescent probe for CO detection without additional reagents. Probe NIR-CO could quantitatively detect CO at the nanomolar level and the detection limit was calculated as low as 6.1 nM. Additionally, probe NIR-CO with preeminent sensing properties was successfully applied to monitor the fluctuations of endogenous CO levels in living systems. In particular, the up-regulation of heme oxygenase-1 (HO-1) caused by transient glucose deprivation (TGD) in living cells and the down-regulation of HO-1 inhibited by high glucose (HG) in zebrafish were confirmed for the first time via mapping the glucose-induced fluctuations of CO levels. Thus, we anticipate that probe NIR-CO not only can serve as a powerful tool to investigate the detailed biological functions of CO in the pathophysiological processes, but also possesses potential applications of in situ monitoring HO-1 activity in the complex biological systems.

Cell-selective imaging of some biological species is significant for the diseases research of a specific tissue or organ. Peroxynitrite (ONOO−) as a kind of reactive nitrogen species (RNS), plays extremely important roles in diverse physiological and pathological processes. Developing cell-specific fluorescent probes for tracing ONOO− in living systems remains a great challenge due to the complexity of internal environment and high autofluorescence. In this work, we developed a galactose-appended hepatoma-specific fluorescent probe Gal-NHP with hydroxynaphthalimide as the fluorophore and hydroquinone moiety as the responsive receptor for sensitively detecting endogenous ONOO− in live HepG2 cells. Probe Gal-NHP could selectively trace ONOO− without interference from other species such as HOCl and H2O2. In addition, the introduction of galactose enhanced the water solubility of this probe, and Gal-NHP could respond quickly to ONOO− in aqueous solution. The quantitative experiment showed the excellent sensitivity of this probe with a good linear relationship. Above all, fluorescence imaging results displayed it possessed excellent hepatoma-specific ability and could successfully detect endogenous ONOO− of hepatoma cells in real time. Thus, this newly developed probe would benefit to reveal the roles of ONOO− in hepatoma cells.

The precise cellular function of peroxynitrite (ONOO–) in biosystems remains elusive, primarily owing to being short of ultrasensitive techniques for monitoring its intracellular distribution. In t...

It is very important to detect native hypochlorous acid (HOCl) in the complex biosystems owing to the important roles of HOCl in the immune defense and the pathogenesis of numerous diseases. In this paper, a new p-aminophenylether-based fluorescent probe PAPE-HA was developed for specific detection of HOCl. Probe PAPE-HA could implement the quantitative detection of HOCl ranging from 0 to 1 μM and the detection limit was obtained as low as 1.37 nM. Additionally, probe PAPE-HA could reach a rapid response for HOCl (2 min). Importantly, probe PAPE-HA with preeminent specificity and ultrasensitivity was proven to possess powerful capability of tracking native HOCl in live cells and zebrafish, and we thus anticipate that probe PAPE-HA could be used as a novel promising tool for revealing diverse cellular functions of HOCl.

A water-soluble fluorescent probe for monitoring thiophenols based on a GFP-type TPC-OH fluorophore and a 2,4-dinitrophenyl ether recognition unit was designed. This probe possessed remarkable sensitivity and specificity toward thiophenols in an almost pure aqueous solution, and also showed good interference immunity to other related analytes including aliphatic mercaptans. Meanwhile, the probe displayed a prominent linear correlation between the thiophenol concentrations in the range of 0 to 20 μM and the fluorescence intensities at 492 nm, and the detection limit was as low as 33 nM. More strikingly, probe 1 was employed to visualize thiophenol in both living cells and zebrafish, which further demonstrated that probe 1 was a powerful practical tool in monitoring thiophenols in living systems.

Peroxynitrite (ONOO−) is a reactive and short-lived biological oxidant endogenously generated in biosystems, and its excessive production is related to various diseases. However, the functional mechanisms of ONOO− are not fully understood. Here, we present a novel ratiometric fluorescent probe CPD-ratio for the accurate detection of ONOO− under single wavelength excitation. This study showed that the probe CPD-ratio can achieve the ratiometric detection of ONOO− with rapid response, and it possessed excellent selectivity and sensitivity (detection limit was calculated to be 47 nM). These properties and its non-toxicity demonstrated that probe CPD-ratio could be potentially employed to accurately monitor ONOO− levels in biological systems. We have thoroughly demonstrated the utility of the probe CPD-ratio for ratiometric bioimaging, because it has been effectively used to trace the exogenous and endogenous ONOO− in live cells.

The detection of ionic mercury (Hg2+) is very important because it is a highly toxic environmental pollutant that could cause serious diseases and threaten human health. Herein, we designed a new carbonothioate-based far-red fluorescent probe, CBRB, with a seminaphthorhodafluor dye as the fluorophore for the detection of Hg2+. The CBRB probe by itself exhibited very weak fluorescence due to the enhanced photo-induced electron transfer (PET) effect and inhibited the intramolecular charge transfer (ICT) process caused by the carbonothioate moiety. Upon addition of Hg2+, a tremendous fluorescence enhancement was achieved, attributed to the removal of the carbonothioate group via a specific mercury-promoted desulfurization reaction. Moreover, the probe displayed a large Stokes shift (about 105 nm) and was used to quantitatively measure the concentration of Hg2+ for concentrations ranging from 0 to 1 μM (DL = 3.6 nM). In addition, CBRB in our experiments responded exclusively to Hg2+, even in the presence of high concentrations other ions. Gratifyingly, this probe was successfully used to monitor Hg2+ in environmental water samples and to image Hg2+ in living cells as well as in zebrafish.

A novel pH-sensitive fluorescent probe has been designed and synthesized for sensing intracellular pH. This probe showed excellent water solubility, it was sensitive toward the pH range from 4 to 12, and it was especially sensitive in alkaline environments. During the pH changes from acidic to alkaline environments, the color of the solution turned from yellow to purple, thus the difference in color can be used to distinguish between acidic and alkaline systems. The other major features of probe pH-DCN including high selectivity, low toxicity, good reversibility and stability allowed pH-DCN to visualize fluctuations of the pH in live cells. Moreover, probe pH-DCN has successfully discriminated cancer cells from normal cells by monitoring their different intracellular pH levels.

In this work, a simple dichlororesorufin-based colorimetric and fluorescent probe R-Hg with the recognition receptor of carbonothioate was designed, synthesized, and exploited to determine mercury ions in aqueous solution and living cells as well as in zebrafish. After a series of analytical tests, probe R-Hg showed some excellent characteristics, such as ultrasensitivity, high selectivity, and good water solubility. The probe solution exhibited a very large fluorescence enhancement (about 150-fold) upon addition of Hg2+. Additionally, probe R-Hg exhibited excellent sensitivity, which could quantificationally detect Hg2+ at the nanomolar level, and the detection limit was 0.49 nM. Moreover, probe R-Hg could be used as a “naked-eye” probe for monitoring Hg2+, because the color of its solution transformed remarkably from yellow into pink with the participation of Hg2+. Importantly, probe R-Hg has potential application value and has been successfully applied to the determination of Hg2+ in practical water sa...

We have synthesized a simple Golgi-targeting H

Mercury (Hg) is a heavy metal with high toxicity and easy migration; it can be enriched through the food chain, and cause serious threats to the natural environment and human health. So, the development of a method that can be used to detect mercury ions (Hg

Early treatment is the best choice for cancer treatment. But there are many difficulties in the early diagnosis of cancer. Fluorescent probes can be used to detect small molecules or proteins overexpressed in tumor cells as a screening tool for tumor cells. However, many analytes are not specifically expressed in tumor cells. Therefore, the sensitivity and accuracy are both limited. Previous studies have shown that hydrogen peroxide (H2O2) is overexpressed in tumor cells. Similarly, melatonin can effectively bind to G-protein coupled receptors (MT1 and MT2), which are also overexpressed in some types of tumor cells. Hence, we constructed a novel melatonin-based targetable H2O2 fluorescent probe for precisely screening tumor cells. The results showed that the proposed probe can successfully detect endogenous and exogenous H2O2 in living cells and zebrafish, and accurately screen tumor cells. Importantly, this work not only proves the potential targeting capability of melatonin for tumor cells, but also provides new strategy of targeting plus activation for tumor cells screening. Moreover, the proposed probe in this work can serve as a potential tool for early diagnosis of cancer.

Hydrogen sulfide (H2S), a recognized environmental pollutant, comes from a wide range of sources. For example, H2S will be produced in the process of plant protein corruption, the decomposition of domestic sewage and garbage, food processing (wine brewing), etc. and once the concentration is too high, it will cause significant damage of environment and human body. Besides H2S is an important gas signal molecule in vivo, which can be transferred through lipid membrane. Its existence level is closely related to many diseases. If we can “visually” trace the transmembrane transmission of hydrogen sulfide, it will be very helpful for the study of oxidative stress processes, cell protection, signal transduction and related diseases closely related to H2S. Although some probes can detect H2S in environment, cytoplasm and organelles, there are few reports on the release and internalization of H2S. In this work, we report a H2S fluorescence probe that can retain on the cell membrane, named PCM. The probe PCM can not only detect endogenous and exogenous H2S, but also distinguish them, this provides a general strategy for the construction of probes to detect other biomarkers. In addition, PCM has been successfully applied to the detection of endogenous and exogenous H2S in zebrafish, which has the potential to become a new chemical tool and provide help for the research of H2S-related diseases.

Developing highly specific and ultrasensitive techniques for monitoring hypochlorous acid (HOCl) in the environment and living systems is very important to guarantee its safe use and disclose its diverse biological functions. We herein presented a simple water-soluble lysosome-targeted fluorescent probe TCRH for the detection of HOCl. Probe TCRH could sensitively monitor HOCl at the nanomolar levels with the detection limit of 0.12 nM. Additionally, probe TCRH with the response unit of thiocarbamate could selectively detect HOCl over other various analytes. Furthermore, probe TCRH showed an ultrafast response for HOCl (

In recent years, more and more chemists and biologists pay attention to the research of fluorescent probes, and great progress has been made in the design and application. In this review, we first discuss the excellent photophysical properties of 4-hydroxy-1,8-naphthalimide (HNI) structure, including excellent photostability, high fluorescence quantum yield, and easy modification of the structure. Then, by discussing the fluorescence behavior of the probe in the corresponding recognition process, the contributions of fluorescent probes built on the platform of HNI in the fields of chemical sensing, biological imaging, pharmaceutical chemistry, environment and food safety in the past ten years are systematically introduced (173 references). At the same time, we hope to develop more powerful fluorescent chemical sensors, which can play a more extensive and exciting role in the future.

In recent years, targeting drugs made by physical loading or chemical bonding of drugs on small molecular carriers have shown a very wide application prospect in the field of tumor and cancer treatment. How to achieve the release of drugs in cancer cells has become the core of this research. One of the most important bases for drug localization is to use the difference of small molecular biothiol concentration between cancer cells and normal cells. Details of the changes of biothiol levels in the growth and reproduction of cancer cells are still poorly understood, and the main reason is the lack of sensitive real-time imaging tools for biothiols in cancer cells. In this work, we reasonably designed and synthesized the combination of 4-hydroxy-1,8-naphthalimide and NBD-Cl as a concise fluorescent probe HN-NBD for imaging biothiols in live cells and zebrafish. In addition, due to the advantages of HN-NBD design, it is sufficiently sensitive to biothiols, and further imaging can distinguish cancer cells from normal cells. Probe HN-NBD would be of great significance to biomedical researchers for the study of biothiol-related diseases, the screening of new anticancer drugs, and the early diagnosis and treatment of cancers.

Small molecular biothiols, such as cysteine (Cys), homocysteine (Hcy), reduced glutathione (GSH), and hydrogen sulfide (H2S), play crucial parts in regulating the redox balance of life activities, regulating normal physiological activities and preventing various diseases. Quantitative analysis of these important small molecular substances is very important for revealing their diverse physiological and pathological effects. Although many fluorescent probes have been reported to detect biothiols in cells, it is still not sufficiently advanced to detect biothiols with separated fluorescence emission peak by same wavelength excitation. In our work, we designed a simple conjugate of Nile red and NBD (7-nitro-1,2,3-benzoxadiazole) as long-wavelength fluorescent probe NR-NBD for the simultaneous discrimination of these biothiols at single wavelength excitation. Probe NR-NBD could efficiently discriminate Cys/Hcy, GSH and H2S by two separated fluorescence emission channels and absorption spectra. Importantly, probe NR-NBD has excellent specificity and sensitivity towards the monitoring of endogenous/exogenous Cys/Hcy and GSH/H2S in living cells and zebrafish.

Hypochlorous acid (HOCl) has received special attention by virtue of its pivotal antimicrobial nature, and the appropriate amount of HOCl is beneficial to innate immunity of host to cope with microbial invasion. However, the uncontrollable accumulation of HOCl is implicated in many human diseases and even cancers. Thus, to determine its deeper biological functions, it is significantly important to specifically monitor intracellular HOCl in biosystems. Herein, we rationally designed a simple fluorescent probe

Exploring techniques for monitoring the intracellular signaling molecule carbon monoxide (CO) in biosystems is important to help understand its various cellular functions. Therefore, a simple long-wavelength colorimetric fluorescent probe LW-CO was designed for selectively and sensitively detecting intracellular CO in living systems. Probe LW-CO is ultrasensitive and can track CO levels in the range of 0–1 μM, with a detection limit of about 3.2 nM. Additionally, the obvious color changes of probe LW-CO with CO (yellow to pink) provide a convenient way for on-site detection of CO with the naked eye. Probe LW-CO was applied to track the exogenous levels of CO in RAW264.7 cells. Probe LW-CO proved to be an efficient method for investigating various cellular functions of CO.

Biothiols such as cysteine (Cys), homocysteine (Hcy), glutathione (GSH) and hydrogen sulfide (H2S) are widely found in mammalian cells. They are closely related to the production and metabolic pathways and play very important roles in physiological and pathological activities. Therefore, the quantitative detection of these biothiols is of great significance. Although many fluorescent probes have been successfully used to track biothiols in biological samples, the fluorescence method for simultaneously detecting these biothiols using separated fluorescence emission channels under single wavelength excitation is still immature. In this work, we prepared the conjugate of seminaphthorhodafluor (SNARF) dye and 7-nitro-1,2,3-benzoxadiazole (NBD) using as a simple long-wavelength fluorescent probe SNARF-NBD for specific detection of biothiols. Cys/Hcy and GSH/H2S were identified by two separated fluorescence emission channels under single wavelength excitation, which showed good selectivity and sensitivity. In addition, SNARF-NBD has low cytotoxicity and shows good imaging ability in living cells and zebrafish.

Peroxynitrite (ONOO-) has been proven to participate in various physiological and pathological processes, and may also be a contributing factor in many diseases. In view of this, there is a need to develop detection tools for unambiguously tracking a small amount of endogenous ONOO- to reveal its exact mechanisms. In this paper, a colorimetric and red-emitting fluorescent probe Red-PN, based on a rhodamine-type fluorophore and hydrazide reactive site is described. The probe Red-PN possesses the advantages of rapid response (within 5 s), visual color change (from colorless to pink), preeminent sensitivity (detection limit = 4.3 nM) and selectivity. Because of these outstanding performances, it was possible to accurately detect endogenous ONOO-. It was encouraging that the probe Red-PN could be used effectively for tracking the relatively low levels of endogenous and exogenous ONOO- in living cells and zebrafish. Thus, it is envisioned that the probe Red-PN would have promising prospects in applications for imaging ONOO- in a variety of biological settings.

Liver cancer is a kind of high mortality cancer due to the difficulty of early diagnosis. And according to the reports, the concentration of reactive oxygen species (ROS) was higher in cancer cells than normal cells. Therefore, developing an effective fluorescent probe for hepatoma-selective imaging of hypochlorous acid (HOCl) which is one of the vital ROS is of great importance for understanding the role of HOCl in liver cancer pathogenesis. However, the cell-selective fluorescent probe still remains a difficult task among current reports. Herein, a galactose-appended naphthalimide (Gal-NPA) with p-aminophenylether as a new receptor and galactose moiety as hepatoma targeting unit was synthesized and employed to detect endogenous HOCl in living HepG2 cells. This probe was proved to possess good water solubility and could respond specifically to HOCl. In addition, probe Gal-NPA could completely react to HOCl within 3 s meanwhile accompanied by tremendous fluorescence enhancement. The quantitative linear range between fluorescence intensities and the HOCl concentrations was 0 to 1 μM (detection limit = 0.46 nM). More importantly, fluorescence confocal imaging experiments showed that probe Gal-NPA could discriminate hepatoma cells over other cancer cells and simultaneously trace endogenous HOCl levels in living HepG2 cells. And we thus anticipate that probe Gal-NPA has the potential application for revealing the functions of HOCl in hepatoma cells.

Mercury, as a highly toxic heavy metal, can cause very serious harm to human health and even death in severe cases. Therefore, we synthesized a novel ratiometric fluorescent probe for detecting mercury ions, with mercaptoethanol as the recognition receptor. Probe CMER could determine mercury ions in 0–1.6 μM and the detection limit is 7.6 nM. Moreover, CMER manifested a fast response for Hg2+ (within 5 s) and simultaneously observed that the color changed from light yellow to orange by naked eye. In addition to these preeminent spectral properties, the probe also had satisfactory bioimaging results in RAW 264.7 macrophage cells and zebrafish.

Hypobromous acid is an important reactive oxygen species (ROS), which is involved in operating various cellular functions. However, the abnormal production of HOBr can induce the generation of a variety of diseases. Although fluorescence probes are huge contributor to our understanding of the biological roles of HOBr, relatively few probes have been used to detect HOBr. Hence, we constructed a ratiometric fluorescent probe Ratio-HOBr with high selectivity to sensitively monitor HOBr. Probe Ratio-HOBr exhibited quick response (

It is very important to determine mercury owing to its complex biological poisonousness that could cause various physical diseases and even death. In this study, we designed a novel coumarin-based ratiometric fluorescent probe, CR-Hg, with DL-dithiothreitol moiety as the recognition receptor to detect mercury ions (Hg2+). CR-Hg could realize the quantitative detection of Hg2+ between 0 and 1.4 μM with low detection limit (1.6 nM). Furthermore, CR-Hg could react quickly with Hg2+ in a few seconds and accompanied by color changes from pale yellow to orange. In the end, the applications of CR-Hg in the water samples, living cells and zebrafish more deeply indicated that the probe could serve as a novel promising tool for revealing mercury distribution in the environment and organisms.