A single chemosensor for multiple analytes: fluorogenic and ratiometric absorbance detection of Zn²⁺, Mg²⁺ and F⁻, and its cell imaging

A simple coumarin based sensor 1 has been synthesized from the condensation reaction of 7-hydroxycoumarin and ethylenediamine via the intermediate 7-hydroxy-8-aldehyde-coumarin. As a multiple analysis sensor, 1 can monitor Zn²⁺ with the fluorescence enhanced at 457 nm, and ratiometric detection at 290 nm, 350 nm and 420 nm in DMF/H₂O (1/4, v/v) medium. Sensor 1 can also monitor Mg²⁺ with the fluorescence enhanced at 430 nm, and ratiometric detection at 290 nm, 370 nm and 430 nm in DMF medium through the interaction of chelation enhance fluorescence (CHEF) with metal ions. Furthermore, 1 also can monitor F⁻ with the fluorescence enhanced at 460 nm, and ratiometric detection at 290 nm and 390 nm in DMF medium simultaneously via hydrogen bonding and deprotonation with F− anion. Spectral titration, isothermal titration calorimetry and mass spectrometry revealed that the sensor formed a 1:1 complex with Mg²⁺, Zn²⁺ or F⁻, with stability constants of 4.5 × 10⁶, 3.4 × 10⁶, 8.0 × 10⁴ M⁻1 respectively. The complexation of the ions by 1 was an exothermic reaction driven by entropy processes. Furthermore, the sensor exhibits good membrane-permeability and was capable of monitoring at the intracellular Zn²⁺ level in living cells

Nobiletin Inhibits Expression of Inflammatory Mediators and Regulates JNK/ERK/p38 MAPK and PI3K/Akt Pathways in Human Osteoarthritic Chondrocytes

Purpose: To investigate the anti-inflammatory effects of nobiletin on human osteoarthritic chondrocytes and also to explore possible related molecular events.Methods: Isolated human osteoarthritic chondrocytes were stimulated with IL-1β. The effect of nobiletin (75, 150 or 300 μg) on chondrocyte viability was assessed. Furthermore, the effect on NO production was determined using Griess reagent while the levels of IL-6 and PGE2 were assessed by enzyme linked immunosorbent assay (ELISA). The influence of nobiletin on the expression of COX-2, iNOS and proteins of PI3/Akt, NF-κB and MAPK cascades were also assessed.Results: Nobiletin (75, 150 and 300 μg) significantly (p < 0.05) improved the viability of chondrocytes, and remarkably reduced the levels of NO, IL-6 and PGE2. The expression levels of COX-2 and iNOS both at mRNA and protein levels were strikingly reduced by nobiletin, in a dose-dependent way. In addition, nobiletin caused marked (p < 0.05) down-regulation of the NF-κB signalling pathway. IL-1β- induced activation of PI3/Akt, and JNK, ERK and p38 MAPK cascades were significantly (p < 0.05) inhibited by nobiletin with 300 μg dose exhibiting maximum effects.Conclusion: Inflammatory cytokines are critically involved in the pathogenesis of OA. Significant suppression of cytokines and modulation of PI3/Akt and MAPK signalling cascades by nobiletin suggests its potent anti-inflammatory and anti-osteoarthritic effects.Keywords: Chondrocytes, Inflammation, Mitogen-activated protein kinases, NF-κB, Nobiletin, Osteoarthriti

Phase-retrieval algorithm for the characterization of broadband single attosecond pulses

Citation: Zhao, X., Wei, H., Wu, Y., & Lin, C. D. (2017). Phase-retrieval algorithm for the characterization of broadband single attosecond pulses. Physical Review A, 95(4), 8. doi:10.1103/PhysRevA.95.043407Recent progress in high-order harmonic generation with few-cycle mid-infrared wavelength lasers has pushed light pulses into the water-window region and beyond. These pulses have the bandwidth to support single attosecond pulses down to a few tens of attoseconds. However, the present available techniques for attosecond pulse measurement are not applicable to such pulses. Here we report a phase-retrieval method using the standard photoelectron streaking technique where an attosecond pulse is converted into its electron replica through photoionization of atoms in the presence of a time-delayed infrared laser. The iterative algorithm allows accurate reconstruction of the spectral phase of light pulses, from the extreme-ultraviolet (XUV) to soft x-rays, with pulse durations from hundreds down to a few tens of attoseconds. At the same time, the streaking laser fields, including short pulses that span a few octaves, can also be accurately retrieved. Such well-characterized single attosecond pulses in the XUV to the soft-x-ray region are required for time-resolved probing of inner-shell electronic dynamics of matter at their own timescale of a few tens of attoseconds