A fluorescent probe based on cyclochalcone for detecting peroxynitrite.

A novel cyclic chalcone fluorescent probe C-PN was synthesized to detect ONOO-. After reaction with peroxynitrite, the double bond of C-PN in the cyclic chalcone structure was disconnected, which caused the change of intramolecular charge transfer (ICT) effect, emitting blue fluorescence and quenching orange red fluorescence. Visible to the naked eye, the color of the probe solution changed. The probe showed low sensitivity (detection limit = 20.2 nm), short response time (less than 60 s) at low concentration of ONOO-, good visibility, and good selectivity and stability for ONOO-.

Monitoring intracellular pH using a hemicyanine-based ratiometric fluorescent probe.

Monitoring intracellular pH using ratiometric fluorescent probes can provide further insights into various biological processes including many diseases. Although ratiometric fluorescent probes with dual emission can efficiently exclude interferences (probe concentration, instrumental efficiency, and environmental conditions) compared with traditional off-on fluorescent probes, development of pH-responsive fluorescent probes with dual emission remains relatively unexplored and challenging. Herein we reported a new hemicyanine-based ratiometric fluorescent probe 1 with a hydroxyl group. The probe 1 exhibits dual emission and shows a real-time and selective fluorescence response to micro-environmental pH conditions in a range of 6.0 âˆ¼ 8.0. Further studies revealed that 1 could exclusively enter and accumulate into mitochondria and monitor the pH micro-environmental conditions through fluorescence imaging in HepG2 cells. We suggest that this probe might be used as a probe to elucidate the role of pH in many physiological processes.

A coumarin-based fluorescent probe: single-wavelength excitation, discrimination of Cys/Hcy and GSH by naked eyes.

Biothiols mainly include cysteine (Cys), homocysteine (Hcy) and glutathione (GSH), which play an important role in life activities and abnormal changes in their concentrations are closely related to certain diseases. Therefore, the quantitative tracking and analysis of biothiols in living organisms has become a hot research topic in recent years. In this work, a coumarin-based fluorescent probe COUN was designed and synthesized for the comparable color recognition of Cys/Hcy and GSH by introducing the phenylethynyl group as the recognition site of biothiols, which showed significant fluorescence enhancement and green fluorescence under the UV light at 365 nm. The probe specifically recognized Hcy, showing 40-fold fluorescence enhancement and strong green fluorescence at 492 nm. Moreover, there was a good linear relationship between the fluorescence intensity of the probe and certain concentrations of Cys/Hcy and GSH, with detection limits of 36.6 nM, 86.4 nM, and 174 nM, respectively. The recognition mechanism of COUN to distinguish Cys/Hcy and GSH was studied by TDDFT calculations. More importantly, COUN was successfully used for imaging biothiols in living cells. The results showed that this probe could provide an effective contribution to the understanding of the role of biothiols, especially Hcy.

Coumarin-cyanine hybrid: A ratiometric fluorescent probe for accurate detection of peroxynitrite in mitochondria.

There is an urgent need to develop highly sensitive and selective fluorescence probes for ONOO- in mitochondria. Herein, we reported a ratiometric fluorescent probe COUS with coumarin-cyanine hybrid as fluorophore and C = C bonds as reaction sites of ONOO-. The probe COUS was sensitive and selective to ONOO-, and had a large fluorescence emission shift (239 nm) as well as a low detection limit (41.88 nM). Moreover, COUS showed the mitochondrial targeting ability, and the targeting moiety could dissociate from the probe when reacting with ONOO-, which enabled COUS to accurately detect ONOO- in mitochondria.

A hemicyanine-based near-infrared fluorescent probe for vapor-phase hydrazine detection and bioimaging in a complete aqueous media.

A novel near-infrared fluorescent probe CyOE based on hemicyanine dye containing acetyl as a recognition site is reported. The probe CyOE shows high selectivity and sensitivity (LOD = 82 nM, 2.58 ppb), as well as good water solubility and quantitative detectability of hydrazine in the concentration range of 0-75 µM (R2 = 0.993). Moreover, CyOE has a significant increase in fluorescence at 735 nm with the addition of N2H4, which provides a rapid, colorimetric and gas-phase detection method for N2H4 in both aqueous solution and real water samples. In addition, CyOE is successfully utilized to visualize hydrazine in cells with low cytotoxicity and high cell permeability.

[Threshold Flux and Membrane Fouling Analysis of the Hybrid Pre-ozonation and CNTs Membrane Modification Process].

Polyvinylidene fluoride (PVDF) hollow fiber ultrafiltration membranes were modified with carbon nanotubes (CNT). Hybrid pre-ozonation and CNT modification were investigated by experimentally manipulating the ozonation process, threshold flux, and membrane fouling. The results showed that the threshold fluxes of the unmodified membrane and hybrid process were 45 L·(m2·h)-1 and 81 L·(m2·h)-1, respectively. Additionally, the fouling rate of the hybrid process was about 0.00137 kPa·min-1·L-1·m2·h, which was notably lower compared to other process. The results showed that the filtration volume under threshold flux was higher than that under critical flux with the same CNT loading mass and ozone dosage. This comparison indicated that membrane fouling was alleviated under threshold flux and that the corresponding operation period was extended. Through the carbon balance experiment, the fouling capacity and recoverability improved remarkably after CNT modification. Additionally, ozonation could enhance the recoverability of membranes. The hybrid process examined in this study could dramatically improve the permeability and extend the operation time of the ultrafiltration membrane.

[Effect of Hybrid Process of Pre-ozonation and CNT Modification on Hollow Fiber Membrane Fouling Control].

Polyvinylidene fluoride (PVDF) hollow fiber ultrafiltration membranes were modified with carbon nanotube (CNT). Combined with the ozonation process, the effect of the hybrid pre-ozonation and CNT modification on fouling alleviation was investigated. The impacts of CNT loading mass and ozone dosage on the variation of flux and antifouling ability of the membrane modules were evaluated. Under a critical flux of 144 L·(m2·h)-1, CNT loading mass of 3 g·m-2, and ozone dosage(O3/DOC) of 0.22 mg·mg-1, the results revealed that the filtration volume of the hybrid process was promoted to 850 L·m-2, which was about 4.5 times higher than that of the original unmodified membrane. With a flux of 18 L·(m2·h)-1 and 15 day operation, the filtration volume was promoted to 3000 L·m-2, which was 10 times that of the unmodified membrane. The fouling membrane surface was observed using confocal laser scanning electron microscopy (CLSM). The results demonstrated that more living bacteria were present on the membrane surface of the unmodified membrane, which showed a rapid transmembrane pressure (TMP) increase. Both pre-ozonation and CNT modification decreased the total amount of microorganisms and the amount of the living bacteria as well, which mitigated the increase in TMP. After pre-ozonation, the presence of a CNT layer on the membrane surface further decreased the number of living bacteria. Although the CNT layer captured some dead bacteria, it had no obvious relationship with the increase in TMP.

Astaxanthin attenuates total body irradiation-induced hematopoietic system injury in mice via inhibition of oxidative stress and apoptosis.

BACKGROUND: The hematopoietic system is especially sensitive to total body irradiation (TBI), and myelosuppression is one of the major effects of TBI. Astaxanthin (ATX) is a powerful natural anti-oxidant with low toxicity. In this study, the effect of ATX on hematopoietic system injury after TBI was investigated. METHODS: Flow cytometry was used to detect the proportion of hematopoietic progenitor cells (HPCs) and hematopoietic stem cells (HSCs), the level of intracellular reactive oxygen species (ROS), expression of cytochrome C, cell apoptosis, and NRF2-related proteins. Immunofluorescence staining was used to detect Nrf2 translocation. Western blot analysis was used to evaluate the expression of apoptotic-related proteins. Enzymatic activities assay kits were used to analyze SOD2, CAT, and GPX1 activities. RESULTS: Compared with the TBI group, ATX can improve radiation-induced skewed differentiation of peripheral blood cells and accelerate hematopoietic self-renewal and regeneration. The radio-protective effect of ATX is probably attributable to the scavenging of ROS and the reduction of cell apoptosis. These changes were associated with increased activation of Nrf2 and downstream anti-oxidative proteins, and regulation of apoptotic-related proteins. CONCLUSIONS: This study suggests that ATX could be used as a potent therapeutic agent to protect the hematopoietic system against TBI-induced bone marrow suppression.

Regulation of colorectal carcinoma stemness, growth, and metastasis by an miR-200c-Sox2-negative feedback loop mechanism.

PURPOSE: To elucidate a novel mechanism of miR-200c in the regulation of stemness, growth, and metastasis in colorectal carcinoma (CRC). EXPERIMENTAL DESIGN: Quantitative reverse transcription PCR was used to quantify miR-200c expression in CRC cell lines and tissues. A luciferase assay was adopted for the target evaluation. The functional effects of miR-200c in CRC cells were assessed by its forced or inhibited expression using lentiviruses. RESULTS: MiR-200c was statistically lower in CRC clinical specimens and highly metastatic CRC cell lines compared with their counterparts. Sox2 was validated as a target for miR-200c. The knockdown of miR-200c significantly enhanced proliferation, migration, and invasion in CRC cell lines, whereas the upregulation of miR-200c exhibited an inverse effect. Moreover, rescue of Sox2 expression could abolish the effect of the upregulation of miR-200c. In addition, the reduction of miR-200c increased the expression of CRC stem cell markers and the sphere-forming capacity of CRC cell lines. Further study has shown that miR-200c and Sox2 reciprocally control their expression through a feedback loop. MiR-200c suppresses the expression of Sox2 to block the activity of the phosphoinositide 3-kinase (PI3K)-AKT pathway. CONCLUSION: Our findings indicate that miR-200c regulates Sox2 expression through a feedback loop and is associated with CRC stemness, growth, and metastasis.