A highly sensitive ratiometric fluorescent probe for detecting HSO3-/SO32- and viscosity change based on FRET/TICT mechanism

BACKGROUND

Sulfur dioxide (SO2) is a significant gas signaling molecule in organisms, and viscosity is a crucial parameter of the cellular microenvironment. They are both involved in regulating many physiological processes in the human body. However, abnormalities in SO2 and viscosity levels are associated with various diseases, such as cardiovascular disease, lung cancer, respiratory diseases, neurological disorders, diabetes and Alzheimer's disease. Hence, it is essential to explore novel and efficient fluorescent probes for simultaneously monitoring SO2 and viscosity in organisms.

RESULTS

We selected quinolinium salt with good stability, high fluorescence intensity, good solubility and low cytotoxicity as the fluorophore and developed a highly sensitive ratiometric probe QQD to identify SO2 and viscosity changes based on Förster resonance energy transfer/twisted intramolecular charge transfer (FRET/TICT) mechanism. Excitingly, compared with other probes for SO2 detection, QQD not only identified HSO3-/SO32- with a large Stokes shift (218 nm), low detection limit (1.87 μM), good selectivity, high energy transfer efficiency (92 %) and wide recognition range (1.87-200 μM), but also identified viscosity with a 26-fold fluorescence enhancement and good linearity. Crucially, QQD was applied to detect HSO3-/SO32- and viscosity in actual water and food samples. In addition, QQD had low toxicity and good photostability for imaging HSO3-/SO32- and viscosity in cells. These results confirmed the feasibility and reliability of QQD for HSO3-/SO32- and viscosity imaging and environmental detection.

SIGNIFICANCE

We reported a unique ratiometric probe QQD for detecting HSO3-/SO32- and viscosity based on the quinolinium skeleton. In addition to detecting HSO3-/SO32- and viscosity change in actual water and food samples, QQD could also monitor the variations of HSO3-/SO32- and viscosity in cells, which provided an experimental basis for further exploration of the role of SO2 derivatives and viscosity in biological systems.

A near-infrared fluorescent probe for simultaneous detection of pH and viscosity

In this work, we developed a ratiometric fluorescent probe (NT) based on ICT framework in near-infrared (NIR) which could detect pH and viscosity simultaneously. Long emission wavelength in NIR could protect the probe from interference of background fluorescence and improve the accuracy of the test. Due to the presence of thiazole-salt, the probe possessed good water solubility and could respond immediately to pH in water system. The pH values measured by NT in the actual samples were not much different from that measured by the pH meter, therefore, NT could give excellent accuracy. NT realized the reversible detection of pH by protonation and deprotonation. NT was used successfully to detect the pH of actual water samples, human serum and meat, as well as the viscosity variation caused by thickeners. Additionally, NT could monitor the changes of pH and viscosity in living cells. Therefore, the novel probe exhibited potential application in the fields of the environment, human health and food safety evaluation.

NBD-based colorimetric and ratiometric fluorescent probe in NIR for bisulfite

This work presented a FRET-ICT based fluorescent probe (named NTC) composed of coumarin-benzothiazole as the acceptor and 4-nitrobenzo[c][1,2,5] oxadiazole (NBD) as the donor for the detection of SO2 derivatives in NIR. Probe NTC possessed superior performance including selectivity, quickly response toward SO32-/HSO3- and high energy transfer efficiency (94 %). The test strips provided a simple and effective tool in detecting the presence of bisulfite. Besides, NTC was applied to test the sulfur dioxide derivatives in food samples and cells.

A near-infrared fluorescent probe based FRET for ratiometric sensing of H2O2 and viscosity in live cells

Hydrogen peroxide (H2O2) and viscosity play vital roles in the cellular environment as signaling molecule and microenvironment parameter, respectively, and are associated with many physiological and pathological processes in biological systems. We developed a near-infrared fluorescent probe, CQ, which performed colorimetric and ratiometric detection of H2O2 and viscosity based on the FRET mechanism, and was capable of monitoring changes in viscosity and H2O2 levels simultaneously through two different channels. Based on the specific reaction of H2O2 with borate ester, CQ exhibited a significant ratiometric response to H2O2 with a large Stokes shift of 221 nm, a detection limit of 0.87 μM, a near-infrared emission wavelength of 671 nm, a response time of 1 h, a wide detection ranges of 0.87-800 μM and a high energy transfer efficiency of 99.9 %. CQ could also recognize viscosity by the TICT mechanism, and efficiently detect viscosity changes caused by food thickeners. More importantly, CQ could successfully detect endogenous/exogenous H2O2 and viscosity in live HeLa cells, which was expected to be a practical tool for detecting H2O2 and viscosity in live cells.

A FRET-based ratiometric fluorescent probe for sensing bisulfite/sulfite and viscosity and its applications in food, water samples and test strips

A FRET-based ratiometric dual-response fluorescent probe, CQI, constructed by combining quinolinium-indole as the acceptor and coumarin as the donor, was developed for sensing HSO3-/SO32- and viscosity. After the interaction of probe CQI with the analyte, we achieved a green channel for the response to HSO3-/SO32- and an orange channel for the response to viscosity. We comprehensively evaluated the ability of CQI to detect SO2 derivatives and viscosity using fluorescence spectroscopy. Probe CQI exhibited a large Stokes shift (196 nm), a high energy transfer efficiency (99.6 %) and a wide detection range (0-250 μM). The fluorescence intensity of the probe increased up to 14-fold with increasing viscosity, and CQI could detect the viscosity of food thickeners. More importantly, probe CQI could not only successfully monitor SO2 derivatives in various food and water samples, but also be prepared as bisulfite test strips.

A novel ratiometric fluorescence probe based on the FRET-ICT mechanism for detecting fluoride ions and viscosity

Fluoride ion is not only important for dental health, but also a contributing factor in a variety of diseases. At the same time, fluoride ions and cell viscosity are both important to the physiological environment of mitochondria. We developed a dual-response ratiometric fluorescent probe BDF based on Förster resonance energy transfer (FRET) and intramolecular charge transfer (ICT) mechanism for the detection of F- and viscosity. BDF has an outstanding intramolecular energy transfer efficiency of 97.7% and shows excellent performance for fluorine ion detection. In addition, when the system viscosity increases, the fluorescence emission intensity of BDF is greatly heightened, indicating the possibility of viscosity detection. Finally, based on the fluorescence properties of BDF, we used the probe to detect F- in the toothpaste sample and image exogenous fluoride ions in HeLa cells.

A ratiometric fluorescent probe based on the FRET platform for the detection of sulfur dioxide derivatives and viscosity

BACKGROUND

Sulfur dioxide (SO2) is a common gaseous pollutant that significantly threatens environmental pollution and human health. Meanwhile, viscosity is an essential parameter of the intracellular microenvironment, manipulating many physiological roles such as nutrient transport, metabolism, signaling regulation and apoptosis. Currently, most of the fluorescent probes used for detecting SO2 derivatives and viscosity are single-emission probes or probes based on the ICT mechanism, which suffer from short emission wavelengths, small Stokes shifts or susceptibility to environmental background. Therefore, the development of powerful high-performance probes for real-time monitoring of sulfur dioxide derivatives and viscosity is of great significance for human health.

RESULTS

In this research, we designed the fluorescent probe QQC to detect SO2 derivatives and viscosity based on FRET platform with quinolinium salt as donor and quinolinium-carbazole as acceptor. QQC exhibited a ratiometric fluorescence response to SO2 with a low detection limit (0.09 μM), large Stokes shift (186 nm) and high energy transfer efficiency (95 %), indicating that probe QQC had good sensitivity and specificity. In addition, QQC was sensitive to viscosity, with an 9.10-folds enhancement of orange fluorescence and an excellent linear relationship (R2 = 0.98) between the logarithm of fluorescence intensity at 592 nm and viscosity. Importantly, QQC could not only recognize SO2 derivatives in real water samples and food, but also detect viscosity changes caused by food thickeners and thereby had broad market application prospects.

SIGNIFICANCE

We have developed a ratiometric fluorescent probe based on the FRET platform for detecting sulfur dioxide derivatives and viscosity. QQC could not only successfully detect SO2 derivatives in food and water samples, but also be made into test strips for detecting HSO3-/SO32- solution. In addition, the probe was also used to detect viscosity changes caused by food thickeners. Therefore, this novel probe had significant value in food and environmental detection applications.

An efficient dual-function fluorescent probe for sulfites and sulfides and its imaging application in cells

As gas signaling molecules in organisms, SO2 derivatives and H2S play crucial regulating roles in a series of physiological processes. Therefore, developing an assay that can accurately monitor the concentration of SO2 derivatives and H2S in cells is extremely important for the research and treatment of related illnesses. A bifunctional probe SN-F based on FRET mechanism for SO2 derivatives and H2S was designed. SN-F had a short response time to SO2 (2 min), excellent anti-interference capability and selectivity in the non-organic solvent system (pH = 7.4), which was suitable for the determination of SO2 derivatives in cells. SN-F had a wide linear range for H2S. Moreover, SN-F was applied in cell imaging successfully with high targeting ability to endoplasmic reticulum (ER) and could monitor endogenous and exogenous H2S in cells.

A benzothiazole-salt-based fluorescent probe for precise monitoring the changes of pH and viscosity

This work presented a novel ratiometric fluorescent probe (NBO) based on benzothiazole dye, which could monitor the pH fluctuations with high sensitivity via the intramolecular charge transfer (ICT) process. NBO was developed with a good linear response in the pH range of 5.75-7.00 (pKa = 6.5) and a reversible structural change in acidic and alkaline environments. Besides, NBO also has the potential to detect the viscosity changes. Meanwhile, NBO has been successfully applied to the pH monitoring of a variety of water samples in natural environment and human serum. With the treatment of different solutions at pH 2.0 - pH 9.0, the test strips showed significant color changes under both 365 nm UV lamp and room light. When the test strips were applied to white wine, pH could be detected quickly and easily by the naked eyes. Therefore, a novel probe that can be used to detect pH in environment, human serum and food has been successfully developed.

Grp94 Inhibitor HCP1 Suppressed the Replication of SVA in BHK-21 Cells and PK-15 Cells

BACKGROUND

Glucoregulatory protein 94 (Grp94) is necessary for the post-viral life cycle and plays a quality control role in viral proteins, but the role of Grp94 in regulating viral replication in host cells is not well known. Therefore, finding a compound that can regulate Grp94 will help us to study the mechanism of viral replication. Previously, we synthesized a coumarin pyrazoline derivative HCP1 that is an effective inhibitor of Grp94. We suppose that HCP1 may inhibit viral replication.

OBJECTIVE

This study aimed to investigate the effect of HCP1 on the replication ability of Senecavirus A (SVA), so as to provide a target and a leading compound for revealing the pathogenic mechanism of the virus and developing antiviral drugs.

METHODS

Rat cell lines BHK-21 and porcine cell lines PK-15 were infected with SVA, and the infected cells were treated with different concentrations of HCP1. The cell viability (CCK-8), virus titer (TCID50), autophagy level, and Grp94 expression were measured.

RESULTS

The results showed that a low concentration of HCP1 decreased viral titer and viral load in BHK-21 and PK-15 cells, and 5μM HCP1 significantly decreased the expression of SVA VP2 protein. In addition, SVA infection can lead to an increased level of autophagy, and HCP1 can inhibit host cell autophagy caused by SVA infection, thereby inhibiting viral replication and infection.

CONCLUSION

These findings reveal that Grp94 is a key factor in controlling SVA replication, and its inhibitor HCP1 suppresses SVA replication by inhibiting the increase of Grp94 protein level and autophagy induced by SVA. This study will contribute to the development of a new class of small-molecule antiviral drugs.

FRET-based fluorescent probe with favorable water solubility for simultaneous detection of SO2 derivatives and viscosity

The intracellular viscosity is an important parameter of the microenvironment and SO₂ is a vital gas signal molecule. At present, some dual-response fluorescence probes for simultaneous measurements of viscosity and SO₂ derivatives (HSO₃^-/SO₃^2-) possessed poor water solubility. In this work, we developed a water-soluble fluorescence probe CIJ (0.0864 g/100 mL of water at 20 °C) for simultaneous measurements of viscosity and SO₂ derivatives. CIJ exhibited a sensitive fluorescence enhancement to environmental viscosity from 0.97 to 28.04 cP based on a twisted intramolecular charge transfer mechanism and was applied to effective measurement of viscosity in vitro and in vivo. CIJ could also respond to SO₂ derivatives with a low detection limit (44 nM) and a fast response time (5 min) based on the nucleophilic addition reaction. Furthermore, CIJ was applied to monitor SO₂ derivatives in ratiometric response manner in living cells.

A novel sulfur dioxide probe inhibits high glucose-induced endothelial cell senescence

Sulfur dioxide (SO₂) is an important gas signal molecule produced in the cardiovascular system, so it has an important regulatory effect on human umbilical vascular endothelial cells (HUVECs). Studies have shown that high glucose (HG) has become the main cause of endothelial dysfunction and aging. However, the mechanism by which SO₂ regulates the senescence of vascular endothelial cells induced by HG has not yet been clarified, so it is necessary to find effective tools to elucidate the effect of SO₂ on senescence of HUVECs. In this paper, we identified a novel sulfur dioxide probe (2-(4-(dimethylamino)styryl)-1,1,3-trimethyl-1H-benzo [e]indol-3-ium, DLC) that inhibited the senescence of HUVECs. Our results suggested that DLC facilitated lipid droplets (LDs) translocation to lysosomes and triggered upregulation of LAMP1 protein levels by targeting LDs. Further study elucidated that DLC inhibited HG-induced HUVECs senescence by promoting the decomposition of LDs and protecting the proton channel of V-ATPase on lysosomes. In conclusion, our study revealed the regulatory effect of lipid droplet-targeted sulfur dioxide probes DLC on HG-induced HUVECs senescence. At the same time, it provided the new experimental evidence for elucidating the regulatory mechanism of intracellular gas signaling molecule sulfur dioxide on vascular endothelial fate.

An imidazo[1,5-α]pyridines-based ratiometric fluorescent probe for sensing sulfur dioxide derivatives in real samples based on a FRET mechanism

A novel fluorescence resonance energy transfer (FRET)-based ratiometric emission fluorescent probe AT was designed and developed in which the imidazo[1,5-α]pyridine was served as a FRET donor and tricyanofuran (TCF) as the FRET acceptor to detect SO₃^2-/HSO₃^- based on the Michael addition reaction. Probe AT had a high energy transfer efficiency (95%) and a large pseudo-Stokes shift (259 nm) in EtOH/PBS buffer (5/5, v/v). It also possessed good selectivity and quick response to SO₃^2-/HSO₃^-. There was good linearity between the ratio of fluorescence intensity (F₄₉₉/F₆₄₅) and the concentrations of SO₃^2-/HSO₃^- in the ranges of 1.5-7.5 μM and 9-20 μM, with calculated detection limits (LOD) of 55 nM. In addition, the probe could also detect the concentrations of SO₃^2-/HSO₃^- in real samples such as environmental water and sugar, allowing the probe to be used in a variety of applications.

A spectroscopic probe with FRET-ICT feature for thiophenol monitoring in real water samples

Thiophenol (PhSH) is widely used in industry, however, it is extremely harmful to the environment and human health due to its high toxicity. In this work, we developed a new FRET-ICT-based ratiometric fluorescent and colorimetric probe (DMNP) for detecting PhSH. DMNP had an ultrahigh energy transfer efficiency (99.7%) and clear spacing of two emission peaks (133 nm). DMNP achieved a fast response to PhSH and exhibited drastic enhancement (over 2100 folds) of the fluorescence intensity ratio upon addition of PhSH. DMNP showed good linear response in the PhSH concentration ranges of 0.5-13 μM and 17.0-22.0 μM. Meanwhile, DMNP could also be applied to monitor PhSH in a variety of real water samples.

Identification of a new way to induce differentiation of dermal fibroblasts into vascular endothelial cells

Background

Human dermal fibroblasts (HDFs) have the potential to differentiate into vascular endothelial cells (VECs), but their differentiation rate is low and the mechanism involved is not clear. The small molecule pathway controls the phenotype of fibroblasts by activating cellular signaling pathways, which is a more convenient method in the differentiation strategy of HDFs into VECs.

Methods

In this study, HDFs were treated with the different doses of CPP ((E)-4-(4-(4-(7-(diethylamino)-2-oxo-2H-chromene-3-carbonyl) piperazin-1-yl) styryl)-1-methylpyridin-1-ium iodide), and the mRNA and protein levels of HDFs were detected by qPCR, Western blot, flow cytometry and immunofluorescent staining. The matrigel assays, acetylated-LDL uptake and angiogenesis assays of chick embryo chorioallantoic membrane (CAM) and hindlimb ischemia model of nude mice were performed to evaluate the functions of VECs derived from HDFs.

Results

Here, we report that the small chemical molecule, CPP, can effectively induce HDFs to differentiate into VECs. First, we observed the morphological changes of HDFS treated with CPP. Flow cytometry, Western blot and qRT-PCR analyses showed that CPP effectively decreased the level of the HDFs-marker Vimentin and increased levels of the VEC-markers CD31, CD133, TEK, ERG, vWF, KDR and CDH5. Detection of the percentage of CD31-positive cells by immunofluorescent staining confirmed that CPP can effectively induce HDFs to differentiate into VECs. The results of Matrigel assays, DiI-ac-LDL uptake, angiogenesis assays on CAM and hindlimb ischemia model of nude mice showed that CPP-induced HDFs have the functions of VECs in vitro and in vivo. Western blot and qRT-PCR analysis showed that CPP induces HDFs to differentiate into VECs by promoting the expression of pro-angiogenic factors (VEGF, FGF-2 and PDGF-BB).

Conclusions

Our data suggest that the small chemical molecule CPP efficiently induces the differentiation of HDFs into VECs. Simultaneously, this new inducer provides a potential to develop new approaches to restore vascular function for the treatment of ischemic vascular diseases.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-03185-4.

A ratiometric fluorescent probe for selective detection of thiophenol derivatives

Though a number of on-off or off-on fluorescent probes have been developed for the detection of thiophenol by using its unique recognition groups, such as 2, 4-dinitrophenyl ether, 2, 4-dinitrophenyl sulfonamide, and 2, 4-dinitrophenyl sulfonate, up to now, there are few probes that can detect thiophenol by the proportional fluorescence signal. We developed a ratiometric fluorescent probe with coumarin pyridine derivative as fluorophore and 2, 4-dinitrophenyl ether moiety as the sensing unit which could be used to detect thiophenol derivatives by the aromatic nucleophilic substitution reaction. This probe (CPBPN) displayed significant change in fluorescence ratio (256 fold) to result in a more reliable analysis by self-calibration and a relatively low detection limit of 24 nM toward 4-methylthiophenol (MTP) within 30 min to achieve more sensitivity. Besides, the probe was also applied to detect the presence of thiophenol derivatives in actual water samples and fluorescence imaging in living cells. The present work is of great importance for monitoring environmental pollutants and studying their biological function.

Two simple but effective turn-on benzothiazole-based fluorescent probes for detecting hydrogen sulfide in real water samples and HeLa cells

Two simple turn-on fluorescent probes, containing a benzothiazole and the 2,4-dinitrobenzenesulfonyl group, were designed for detecting H₂S. Two probes exhibited good selectivity and high sensitivity, which were applied to detect the H₂S in real water samples. Probe P2 with a positive charge had better solubility than probe P1 in water; therefore, probe P2 was successfully applied to detect both the endogenous and exogenous H₂S in lysosomes of living HeLa cells.

A fluorescent probe based on ICT for selective detection of benzenethiol derivatives

This work presented a benzothiazole-based fluorescent probe for the detection of benzenethiol derivatives using 2, 4-dinitrobenzene moiety as a sensing unit. This probe (NCABT) was able to instantaneously respond to 4-methylbenzenethiol (MTP) within 5 min. In detecting MTP, this probe displayed a low limit of detection (49 nM). Furthermore, the probe has been proved to have the potential to detect benzenethiol derivatives with electron-donating group in real water samples.

A new turn-on fluorescent probe for sensing 4-methylbenzenethiol in real water samples

A new fluorescent probe (MBT) for the detection of 4-methylbenzenethiol (p-MePhSH) was developed by using 4-(benzo[d]thiazol-2-yl)-3-methoxyphenol as the fluorophore and 2,4-dinitrophenyl ether as the sensing moiety. Probe MBT displayed good selectivity toward p-MePhSH in DMSO/PBS buffer (5/5, v/v) solution and anti-interference over other competitive species via nucleophilic aromatic substitution. The fluorescence intensities of the probe responded p-MePhSH showed a 22-fold enhancement and good linearity with p-MePhSH concentration collected in the range of 0-15 μM. Moreover, the probe is sensitive to p-MePhSH and the limit of detection is 45 nM. The sensing mechanism of probe MBT was verified by high-resolution mass spectrometry and fluorescence lifetime. Furthermore, the probe was used to the detection of p-MePhSH in real water samples.

Metal-Free Catalyzed Synthesis of Fluorescent Indolizine Derivatives

A mild and high efficient method to prepare indolizines by two-component reaction with the acid as the catalyst was developed. In this reaction, a new ring efficiently formed in one-step reaction. A wide range of substrates could be applied and the desired products were obtained in 8-95% yields under metal-free conditions. Different indolizine derivatives (compounds 3a-3n) were synthesized by general conditions and microwave irradiation conditions, and compound 3a gave the best results with an isolated yield of 95% and 82%, respectively. The structures of synthesized compounds were characterized by spectral analysis, and compound 3m was confirmed by single crystal X-ray analysis. UV-vis absorption and fluorescence properties of these compounds were correlated with substituent groups on indolizine rings.

Identification of a new autophagy inhibitor targeting lipid droplets in vascular endothelial cells

Autophagy of vascular endothelial cells (VECs) plays an important role in maintaining vascular homeostasis. Lipid droplets (LDs) are organelles that can be formed in response to various stimuli, including excessive lipid or various stresses. LDs sequester toxic lipids, thereby preventing lipotoxic cell damage and have a complex relationship with autophagy. In the previous study, we identified a novel Grp94 inhibitor HCP1 inhibited apoptosis in VECs. Here we found that HCP1 targeted LDs and promoted the accumulation of LDs in VECs. Our results showed that HCP1 upregulated the protein levels of autophagy-related proteins. We demonstrated that HCP1 upregulated the number of LDs and suppressed autophagy by inhibiting Grp94. Therefore, we provided HCP1 as a new VECs autophagy inhibitor targeting LDs, which might be a potential compound in the treatment of VECs autophagy related vascular diseases.

A mitochondria-targeted fluorescent probe for the detection of endogenous SO2 derivatives in living cells

A unique fluorescent probe (ZACA) for the monitoring of SO2 derivatives was developed from coumarin and benzoindoles based on FRET and ICT. ZACA exhibited an active emission signal, large Stokes shift, wide emission window distance, and high photostability. It also possessed many advantages in the ratiometric detection of HSO3-/SO32- including low detection limit and high selectivity and sensitivity. Importantly, ZACA was successfully applied in the ratiometric detection of endogenous HSO3-/SO32- in living cells with excellent cellular imaging capability (1 μM) and mitochondria-targeting ability (co-localization coefficient: 0.91).

H2S probe CPC inhibits autophagy and promotes apoptosis by inhibiting glutathionylation of Keap1 at Cys434

H₂S is actual an endogenous signaling gas molecule and involved in a range of cell physiological processes. However, the mechanism of endogenous H₂S regulating autophagy and apoptosis has not been thoroughly investigated. Here, we try to address this issue by using a H₂S probe, (E)-2-(4-(4-(7-(diethylamino)-2-oxo-2H-chromene-3-carbonyl)-piperazin-1-yl)-styryl)-1, 3, 3-trimethyl-3H-indol-1-ium iodide (CPC), which could react with endogenous H₂S. Herein, we reported that CPC inhibited autophagy and decreased the expression and activity of NF-E2-related factor 2 (Nrf2), then induced cell apoptosis. CPC inhibited autophagy and promoted apoptosis by inhibiting Nrf2 activation, which was H₂S dependent. Furthermore, we found that CPC inhibited Nrf2 nucleus translocation by inhibiting glutathionylation of Kelch-like ECH-associated protein 1 (Keap1) at the Cys434 residue. CPC also inhibited various cancer cell growth, but had no effect on normal cell growth in vitro, and inhibited A549 cancer growth, but did not affect normal angiogenesis in vivo. Therefore, we not only found a new inhibitor of autophagy and Nrf2, but also suggested a novel mechanism that endogenous H₂S could regulate autophagy, apoptosis and Nrf2 activity through regulating glutathionylation of Keap1 at the Cys434 residue.

Discovery of a fluorescigenic pyrazoline derivative targeting ubiquitin

Despite significant process in ubiquitin modification by using traditional genetic methods, chemical small molecules that directly target and modify ubiquitin are little reported. Here, we find that a fluorescigenic pyrazoline derivative (FPD5) could do so effectively. Molecule docking revealed that lysine 11 of ubiquitin was the key contact residue. FPD5, with stronger fluorescence, elevated the ubiquitination of beclin 1 (BECN1) and promoted autophagy. This study highlights that targeting ubiquitin by chemical small molecules enables us to modulate ubiquitination and the downstream signaling in the ubiquitin system.

A novel mitochondria-targeted ratiometric fluorescent probe for endogenous sulfur dioxide derivatives as a cancer-detecting tool

A new mitochondria-targeted fluorescent probe RBC, constructed using a coumarin moiety which was selected as the donor and a benzothiazole derivative as the acceptor, for SO₂ derivatives (HSO₃^-/SO₃^2-) was presented. The probe designed on a new FRET platform showed high selectivity and a low detection limit. Importantly, the probe could respond to HSO₃^-/SO₃^2- within 35 s. Furthermore, the probe could target mitochondria and was successfully used for fluorescence imaging of endogenous bisulfite in HepG2 with low cytotoxicity, which significantly assisted in cancer diagnosis.

[Stent placement for filter-related chronic occlusion of the inferior vena cava]

Objective: To assess the technical success rate, stent patency, clinical efficacy and complications of stent placement for filter-related chronic occlusion of the inferior vena cava. Methods: A retrospective analysis was carried out for 12 patients with filter-related chronic occlusion of the inferior vena cava associated with severe post-thrombotic syndrome, who underwent stent placement after ineffective conservative therapy at Nanjing First Hospital from March 2016 to December 2018,9 males and 3 females, aged from 48 to 77 years, mean age 60 years, six had bilateral lower extremity symptoms and six had unilateral lower extremity symptoms.Technical success rate, stent patency, clinical efficacy and complications of stent placement were recorded. Clinical success was defined as relief of symptoms and a decrease in clinical, etiology, anatomy, and pathophysiology (CEAP) score for at least grade 1. Results: Stent placement in the unilateral or bilateral iliocaval occlusion was successful in 11 patients. The cause of technical failure in the single patient with failed stent placement was an inability to cross the occluded left iliacvein and the patient was treated with stent placement in the right iliocaval vein.There were 7 patients with inferior vena cava and unilateral iliocaval stent placement; 5 patients with inferior vena cava and bilateral iliocaval stent placement. Acute stent thrombosis occlusion occurred in 1 case after the operation, the blood flow recanalized after catheter-directed thrombolysis and re-stenting. All patients were followed up for 6 to 24 months, with an average of (13±6) months. During the follow-up period, CTV or venography of lower limbs showed that the blood flow in the stent was unobstructed. At the last follow-up, 12 patients were evaluated as clinically effective. Three patients had transient treatment of lateral lumbar pain during operation, which alleviated by themselves.No significant abdominal pain, severe hemorrhage, symptomatic pulmonary embolism and other complications related to treatment occurred in all patients during perioperative period and follow-up. Conclusion: Stent placement is safe and feasible in the treatment of filter-related chronic occlusion of the inferior vena cava, which can alleviate the clinical symptoms of severe post-thrombotic syndrome.

Discovery of a new autophagy inducer for A549 lung cancer cells

Biological activities of a series of fluorescent compounds against human lung cancer cell line A549 were investigated. The results showed that (E)-1,3,3-trimethyl-2-(4-(piperidin-1-yl)styryl)-3H-indol-1-ium iodide (8) and (E)-2-(5,5-dimethyl-3-(4-(piperazin-1-yl)styryl)cyclohex-2-en-1-ylidene) malononitrile (11) could inhibit the growth of A549 cancer cells in a dose and time-dependent manner. Furthermore, compound 8 could trigger autophagy and apoptosis, but not obviously induce necrosis under the stimulatory condition. Therefore, 8 can be used as autophagy activator to investigate the regulatory mechanism of autophagy and may offer a new candidate for the treatment of lung cancer.

A near-infrared and mitochondria-targeted fluorescence probe for ratiometric monitoring of sulfur dioxide derivatives in living cells

A promising near-infrared emissive and mitochondria-targeted fluorescence probe (SNB) for the ratiometric detection of sulfur dioxide derivatives with a novel reaction mechanism was developed on the basis of FRET and the ICT platform.

Role of TGF‑β1 expressed in bone marrow‑derived mesenchymal stem cells in promoting bone formation in a rabbit femoral defect model

Bone defects represent a major clinical and socioeconomic problem without suitable treatment options. Previous studies have shown that transforming growth factor β1 (TGF‑β1) is important in the development of various diseases. The present study aimed to investigate the therapeutic potential of rabbit bone marrow‑derived mesenchymal stem cells (BMSCs) expressing TGF‑β1 in the treatment of rabbit femoral defects. First, rabbit BMSCs were identified and cultured. TGF‑β1 was then stably overexpressed in the rabbit BMSCs by lentivirus transfection, which was expressed at a high level in the femoral defects treated with TGF‑β1‑overexpressing BMSCs, compared with PBS‑treated controls. In addition, the TGF‑β1‑overexpressing BMSCs promoted new bone formation in the rabbit femoral defect model, and increased the expression of bone‑related markers at week 2 and week 6. Therefore, the study demonstrated that BMSCs overexpressing TGF‑β1 may provide a novel therapeutic option for femoral defects.

Discovery of a novel Nrf2 inhibitor that induces apoptosis of human acute myeloid leukemia cells

Nuclear factor-erythroid 2-related factor 2 (Nrf2) is persistently activated in many human tumors including acute myeloid leukemia (AML). Therefore, inhibition of Nrf2 activity may be a promising target in leukemia therapy. Here, we used an antioxidant response element-luciferase reporter system to identify a novel pyrazolyl hydroxamic acid derivative, 1-(4-(tert-Butyl)benzyl)-3-(4-chlorophenyl)-N-hydroxy-1H pyrazole-5-carboxamide (4f), that inhibited Nrf2 activity. 4f had a profound growth-inhibitory effect on three AML cell lines, THP-1, HL-60 and U937, and a similar anti-growth effect in a chick embryo model. Moreover, flow cytometry of AML cells revealed increased apoptosis with 4f (10 μM) treatment for 48 h. The protein levels of cleaved caspase-3 and cleaved poly (ADP-ribose) polymerase were enhanced in all three AML cell types. Furthermore, Nrf2 protein level was downregulated by 4f. Upregulation of Nrf2 by tert-butylhydroquinone (tBHQ) or Nrf2 overexpression could ameliorate 4f-induced growth inhibition and apoptosis. Treatment with 4f reduced both B-cell lymphoma-2 (Bcl-2) expression and Bcl-2/Bcl-2–associated X protein (Bax) ratio, which indicated that 4f induced apoptosis, at least in part, via mitochondrial-dependent signaling. Therefore, as an Nrf2 inhibitor, the pyrazolyl hydroxamic acid derivative 4f may be a promising agent in AML therapy.

A ratiometric fluorescence probe for rapid detection of mitochondrial SO2 derivatives

In this study, we report a fluorescent probe (CBT) for detecting SO₂ derivatives in ratiometric fluorescence manner.

A new ratiometric fluorescent probe for detecting endogenous HClO in living cells

A new benzimidazole-hemicyanine-based ratiometric fluorescent probe (ZBM-H) was developed, which showed high selectivity and sensitivity for detecting HClO.

A small molecule targeting glutathione activates Nrf2 and inhibits cancer cell growth through promoting Keap-1S-glutathionylation and inducing apoptosis

The level of glutathione (GSH) is increased in many cancer cells. Consuming intracellular GSH by chemical small molecules that specifically target GSH is a new strategy to treat cancer. Recently, we synthesized and proved that a new compound 2-(7-(diethylamino)-2-oxo-2H-chromen-3-yl)cyclohexa-2,5-diene-1,4-dione (PBQC) could target to and consume intracellular GSH specifically, but, it is not clear if PBQC can affect cancer cell growth and the activity of the nuclear factor-erythroid 2-related factor 2 (Nrf2) which is a key factor involved in regulation of cancer cell growth. In this study, we addressed these questions. We found that PBQC suppressed cancer cell growth through increasing the activity of Nrf2, while it did not inhibit normal vascular endothelial cell growth. Furthermore, we demonstrated that PBQC can cause Keap-1 protein S-glutathionylation and promote Nrf2 nuclear translocation as well as the expression of pro-apoptosis genes. As a result, the cancer cells underwent apoptosis. Here, we provide a new Nrf2 activator, PBQC that can promote the expressions of pro-apoptosis genes downstream Nrf2. The data suggest that PBQC is a potential lead-compound for development of new anti-cancer drugs.

The level of glutathione (GSH) is increased in many cancer cells.

Novel indolyl-chalcone derivatives inhibit A549 lung cancer cell growth through activating Nrf-2/HO-1 and inducing apoptosis in vitro and in vivo

Increasing evidence indicates that Nrf-2, named the nuclear factor-erythroid 2-related factor, may perform anticancer function. In this study, a series of novel substituted phenyl- (3-methyl-1H-indol-2-yl)-prop-2-en-1-one (indolyl-chalcone) derivatives were synthesized and their effects on Nrf-2 activity were observed. We found that compounds 3a-3d and 6c elevated Nrf-2 activity. Then we evaluated their anticancer activities in vitro and in vivo by utilizing human lung cancer cell line A549. The in vitro results showed that among the compounds, 3d performed effectively anti-growth activity by inducing A549 lung cancer cell apoptosis and activating Nrf-2/HO-1 (heme oxygenase-1) pathway. In vivo, we proved that compound 3d inhibited the tumor growth effectively through inducing cell apoptosis without affecting CAM normal angiogenesis. These data suggest that our discovery of a novel Nrf-2 activator compound 3d would provide a new point of human lung cancer treatment.

[Application of percutaneous AngioJet thrombectomy in patients with acute symptomatic portal and superior mesenteric venous thrombosis]

Objective: To evaluate the clinical value of percutaneous AngioJet thrombectomy in treatment of acute symptomatic portal and superior mesenteric venous thrombosis venous thrombosis (PVMVT) . Method: From January 2014 to January 2016, a total of 8 patients in Nanjing First Hospital with PVMVT verified by color Doppler ultrasound and computed tomographic angiography (CTA) were analyzed retrospectively. Under ultrasound guidance , the branch of the right portal vein(PV) was punctured with a micropuncture set and a 4-F infusion catheter was advanced to the superior mesenteric vein(SMV). The venogram demonstrated the thrombosis in the PV/SMV and a 6-F AngioJet Xpeeedior catheter was advanced over the guidewire and positioned in the distal SMV. Percutaneous thrombectomy was performed after a mixture of 250 000 U of urokinase in 100 ml of normal saline for mechanical pulse spray of thrombus in all patients for approximately 15 minutes. 2 patients underwent PTA and stent implantation after the thrombectomy procedure, 1 of them and the others 6 patients received continuous transcatheter infusion of urokinase (500 000 U/d) for 24 or 48 hours until the thrombosis was completely dissolved confirmed by angiography at 24 and 48 hours.After procedure and the thrombolytic therapy was discontinued, removal of the infusion catheter and the sheath from the liver, the transhepatic tract was embolized with coils or gelfoam to reduce the risk of bleeding. The patency rate of PV /SMV was assessed by CTA at 1 and 6 months after the procedure. Patients were discharged with oral anticoagulation regimen for at least 6 months.The following criteria were used in evaluation of thrombolysis: grade Ⅰ<50% thrombus removal; grade Ⅱ 50%~90% thrombus removal, and grade Ⅲ>90% thrombus removal. Results: All 8 patients with PVMVT were treated by AngioJet thrombectomy. Angiography after the thrombectomy procedure showed complete thrombus removal (>90%) was in 3 cases, substantial thrombus removal (50%~90%) in 5 cases. Grade Ⅲ (complete) thrombolysis was achieved in 7 cases and grade Ⅱ (50%~90%) lysis in 1 case post thrombolytic therapy for 24 or 48 hours. 2 patients had underwent PTA and stent implantation. Large volume intraperitoneal hemorrhage was discovered in 1 patient after removal of the catheter and sheath from the liver. The patient restored stability after a blood transfusion.Venous patency was comfirmed in all 8 patients at 1 or 6 months after the treatment. There was no patient with major complications death related to the procedure. Conclusion: Percutaneous AngioJet thrombectomy with adjunctive thrombolytic therapy is an effective and safe treatment modality in patients with acute symptomatic PVMVT.

A hydrogen sulfide probe activates Nrf2, inhibits cancer cell growth and induces cell apoptosis

Application of a probe for hydrogen sulfide, HF-NBD.

Fluorescence detection of endogenous bisulfite in liver cancer cells using an effective ESIPT enhanced FRET platform

Probe L-HF1, which featured large (pseudo) Stokes shifts and high FRET efficiency, was designed on a new ESIPT enhanced FRET platform for the detection of HSO₃⁻/SO₃²⁻.

A mitochondria-targeted ratiometric fluorescent probe for hypochlorite and its applications in bioimaging

A novel ratiometric probe (RCP) for ⁻OCl was developed based on the fluorescence resonance energy transfer (FRET) platform.

A new microRNA signal pathway regulated by long noncoding RNA TGFB2-OT1 in autophagy and inflammation of vascular endothelial cells

TGFB2-OT1 (TGFB2 overlapping transcript 1) is a newly discovered long noncoding RNA (lncRNA) derived from the 3'UTR of TGFB2. It can regulate autophagy in vascular endothelial cells (VECs). However, the mechanisms of TGFB2-OT1 action are unclear, and whether it is involved in VECs dysfunction needs investigation. Here, the level of TGFB2-OT1 was markedly increased by lipopolysaccharide and oxidized low-density lipoprotein, 2 VECs inflammation triggers. A chemical small molecule, 3-benzyl-5-((2-nitrophenoxy) methyl)-dihydrofuran-2(3H)-one (3BDO) significantly decreased TGFB2-OT1 levels and inhibited the effect of LPS and oxLDL. The NUPR1 level was upregulated by the 2 inflammation inducers and modulated the TGFB2-OT1 level by promoting the expression of TIA1, responsible for TGFB2-OT1 processing. We focused on how TGFB2-OT1 regulated autophagy and inflammation. Use of miRNA chip assay, TGFB2-OT1 overexpression technology and 3BDO revealed that TGFB2-OT1 regulated the levels of 3 microRNAs, MIR3960, MIR4488 and MIR4459. Further studies confirmed that TGFB2-OT1 acted as a competing endogenous RNA, bound to MIR3960, MIR4488 and MIR4459, then regulated the expression of the miRNA targets CERS1 (ceramide synthase 1), NAT8L (N-acetyltransferase 8-like [GCN5-related, putative]), and LARP1 (La ribonucleoprotein domain family, member 1). CERS1 and NAT8L participate in autophagy by affecting mitochondrial function. TGFB2-OT1 increased the LARP1 level, which promoted SQSTM1 (sequestosome 1) expression, NFKB RELA and CASP1 activation, and then production of IL6, IL8 and IL1B in VECs. Thus, NUPR1 and TIA1 may control the level of TGFB2-OT1, and TGFB2-OT1 bound to MIR3960, MIR4488 and MIR4459, which targeted CERS1, NAT8L, and LARP1, respectively, the key proteins involved in autophagy and inflammation.

A new ratiometric fluorescent probe for rapid, sensitive and selective detection of endogenous hydrogen sulfide in mitochondria

We have developed a new ratiometric fluorescent probe composed of a coumarin-merocyanine dyad based on the FRET mechanism. The probe showed clear dual-emission signal changes in blue and red spectral windows upon addition of H2S in a dose dependent manner under a single wavelength excitation. The probe targeted mitochondria with high selectivity and sensitivity toward H2S.

An effective colorimetric and ratiometric fluorescent probe based FRET with a large Stokes shift for bisulfite

Bisulfite plays crucial roles in diverse physiological processes. Therefore, the efficient detection of bisulfite is very important. In this study, we report a colorimetric and ratiometric fluorescent probe (CPT) with a large Stokes shift (162 nm) for bisulfite (HSO₃⁻) based FRET mechanism. The probe can quantitatively detect HSO₃⁻ with low detection limit (45 nM) and high specificity over other common anions and biothiols. A nucleophilic addition reaction was proposed for the sensing mechanism, which was confirmed by HRMS spectra. The test strips of the probe were made and used easily. Moreover, probe CPT was used to ratiometric fluorescent imaging of exogenous and endogenous HSO₃⁻ in living cells.

A mitochondria-targeted fluorescent probe for ratiometric detection of endogenous sulfur dioxide derivatives in cancer cells

A new mitochondria-targeted fluorescent probe HCy-D, constructed by dansyl and hemicyanine fluorophores, for SO₂derivatives (HSO₃⁻/SO₃²⁻) was presented.