| 1. |
- Hu, Zhang-Jun, et al.
(author)
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Real-time visualizing the regulation of reactive oxygen species on Zn2+ release in cellular lysosome by a specific fluorescent probe
- 2018
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In: Sensors and actuators. B, Chemical. - : ELSEVIER SCIENCE SA. - 0925-4005 .- 1873-3077. ; 264, s. 419-425
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Journal article (peer-reviewed)abstract
- Reactive oxygen species (ROS) regulating the release of free zinc ions (Zn2+) in cellular lysosome is closely related to various pathways of cellular signal transduction, such as inflammation and oxidative stress. Directly visualizing Zn2+ release in lysosome is essential for in-depth understanding these physiological processes, and is still an atelic challenge. In this work, we successfully fabricate a lysosome-specific Zn2+ fluorescent probe and achieve the visualization of ROS-induced Zn2+ release in lysosome of inflammatory cells. The as-prepared probe combines a green fluorophore, an ionophore with five-dentate sites, and a morpholine as the lysosome-specific localization moiety. The fluorescence of the fluorophore in the free probe is suppressed by a photoinduced electron transfer (PET) process from nitrogen atoms in the ionophore. Upon the addition of Zn2+, the fluorescence can be promoted immediately, achieving the real-time detection. Meanwhile, the probe is sensitive and selective to Zn2+, which provides the capability to detect low-concentration of free Zn2+ in lysosomes. Accordingly, the Zn2+ release was clearly observed in lysosome with the increase of ROS levels when the inflammation occurred in living cells. (c) 2018 Published by Elsevier B.V.
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| 2. |
- Li, Guoqiang, et al.
(author)
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A comprehensive dataset of luminescence chronologies and environmental proxy indices of loess-paleosol deposits across Asia
- 2024
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In: npj Climate and Atmospheric Science. - : Springer Nature. - 2397-3722. ; 7:1
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Journal article (peer-reviewed)abstract
- Loess-paleosol sequences have been used in Asia to study climate and environmental changes during the Quaternary. The scarcity of age control datasets and proxy indices analysis data for Asian loess has limited our understanding of loess depositional processes and the reconstruction of paleoclimatic changes from loess-paleosol records. In this study, we present a dataset that includes 1785 quartz optically stimulated luminescence ages and 1038 K-feldspar post-infrared infrared stimulated luminescence ages from 128 loess-paleosol sequences located in different regions of Asia. We generate 38 high-resolution age-depth models of loess records based on the provided datasets. We provide data on 12,365 grain size records, 14,964 magnetic susceptibility records, 2204 CaCO3 content records, and 3326 color reflection records. This dataset contains the most detailed and accurate chronologies and proxy index data for loess records in Asia yet published. It provides fundamental data for understanding the spatial-temporal variations in loess depositional processes and climatic changes across the continent during the mid-late Quaternary.
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| 3. |
- Liedberg, Bo, et al.
(author)
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Self-assembly of alpha-functionalized terthiophenes on gold
- 1997
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In: JOURNAL OF PHYSICAL CHEMISTRY B. - : AMER CHEMICAL SOC. - 1089-5647 .- 1520-6106 .- 1520-5207. ; 101:31, s. 5951-5962
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Journal article (peer-reviewed)abstract
- alpha-Functionalized terthiophenes containing disulfide (-S-T-3-H)(2) and alkanethiol (HS-(CH2)(11)-T-3-H) anchoring groups have been synthesized for direct immobilization onto gold. Monolayer structures of these compounds are prepared by spontaneous assembly from ethanol solutions on evaporated gold substrates and thoroughly characterized by ellipsometry, contact angle goniometry, infrared and X-ray photoelectron spectroscopy, and cyclic voltammetry. The two molecules coordinate to the gold substrate exclusively via the anchoring groups upon formation of gold-thiolate bonds. The kinetics of monolayer formation vary dramatically for the two compounds. The alkanethiol analogue assembles rapidly, within a few minutes, and forms a densely packed and highly organized monolayer, with the alkyl chains in an almost perfect all-trans conformation and the C-alpha-C-alpha axis of the alpha-T-3 units tilted about 14 degrees away from the surface normal. The assembly process is much slower for the disulfide, but an organized monolayer with an average alpha-T-3 chain tilt of about 33 degrees will eventually form when the assembly is allowed to equilibrate with a solution containing the disulfide for at least 1 day. Moreover, the two monolayer assemblies also display a remarkably different electrochemical, behavior. The heterogeneous electron-transfer rate at the disulfide-covered gold substrate is almost indistinguishable from that at bare gold, suggesting that the assembly contains a large number of easily accessible defects. An alternative mechanism for explaining the large electron-transfer rate involving electronic coupling via the conjugated pi-system of the alpha-T-3 units is also proposed. The electrochemical response is significantly reduced for the HS-(CH2)(11)-T-3-H assembly, but another type of defects, the so-called shallow defects originating from sparsely populated areas on the electrode surface, can be identified.
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| 4. |
- Miehe, Georg, et al.
(author)
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The Kobresia pygmaea ecosystem of the Tibetan highlands – Origin, functioning and degradation of the world's largest pastoral alpine ecosystem: Kobresia pastures of Tibet
- 2019
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In: Science of the Total Environment. - : Elsevier BV. - 0048-9697. ; 648, s. 754-771
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Journal article (peer-reviewed)abstract
- With 450,000 km2 Kobresia (syn. Carex) pygmaea dominated pastures in the eastern Tibetan highlands are the world's largest pastoral alpine ecosystem forming a durable turf cover at 3000–6000 m a.s.l. Kobresia's resilience and competitiveness is based on dwarf habit, predominantly below-ground allocation of photo assimilates, mixture of seed production and clonal growth, and high genetic diversity. Kobresia growth is co-limited by livestock-mediated nutrient withdrawal and, in the drier parts of the plateau, low rainfall during the short and cold growing season. Overstocking has caused pasture degradation and soil deterioration over most parts of the Tibetan highlands and is the basis for this man-made ecosystem. Natural autocyclic processes of turf destruction and soil erosion are initiated through polygonal turf cover cracking, and accelerated by soil-dwelling endemic small mammals in the absence of predators. The major consequences of vegetation cover deterioration include the release of large amounts of C, earlier diurnal formation of clouds, and decreased surface temperatures. These effects decrease the recovery potential of Kobresia pastures and make them more vulnerable to anthropogenic pressure and climate change. Traditional migratory rangeland management was sustainable over millennia, and possibly still offers the best strategy to conserve and possibly increase C stocks in the Kobresia turf.
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| 5. |
- Wang, Hong, et al.
(author)
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Real-time tracking of mitochondrial dynamics by a dual-sensitive probe
- 2020
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In: Sensors and actuators. B, Chemical. - : Elsevier. - 0925-4005 .- 1873-3077. ; 320
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Journal article (peer-reviewed)abstract
- Tracking of mitochondrial dynamic processes including their morphology, biogenesis and elimination is of significance to deeply understand mitochondrial physiology and related diseases, which requires simultaneous and discriminative labeling of both mitochondria themselves and correlated downstream organelles. However, the combination of multiple fluorescent probes will bring the large invasive effect that seriously impacts the normal physiological processes of mitochondria within live cells. To address this issue, we herein construct a single molecular probe through the combination of two pH-sensitive fluorogens, hydroxyl-coumarin and rhodamine B, enabling the detection of intracellular microenvironmental pH variations. Importantly, the as-synthesized probe not only accumulates into mitochondria, indicated by cyan emission from hydroxyl-coumarin but also can be delivered to the downstream acidic autolysosomes upon the occurrence of mitophagy, indicated by red emission from rhodamine B. Taking advantage of a two-channel confocal microscopy strategy, we have achieved to real-time track the processes of mitochondrial replication, merge and autophagy.
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| 6. |
- Yang, Guanqing, et al.
(author)
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A Multi-responsive Fluorescent Probe Reveals Mitochondrial Nucleoprotein Dynamics with Reactive Oxygen Species Regulation through Super-resolution Imaging
- 2020
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In: Angewandte Chemie International Edition. - : WILEY-V C H VERLAG GMBH. - 1433-7851 .- 1521-3773. ; 59:37, s. 16154-16160
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Journal article (peer-reviewed)abstract
- Understanding the biomolecular interactions in a specific organelle has been a long-standing challenge because it requires super-resolution imaging to resolve the spatial locations and dynamic interactions of multiple biomacromolecules. Two key difficulties are the scarcity of suitable probes for super-resolution nanoscopy and the complications that arise from the use of multiple probes. Herein, we report a quinolinium derivative probe that is selectively enriched in mitochondria and switches on in three different fluorescence modes in response to hydrogen peroxide (H2O2), proteins, and nucleic acids, enabling the visualization of mitochondrial nucleoprotein dynamics. STED nanoscopy reveals that the proteins localize at mitochondrial cristae and largely fuse with nucleic acids to form nucleoproteins, whereas increasing H(2)O(2)level leads to disassociation of nucleic acid-protein complexes.
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| 7. |
- Yang, Zhongping, et al.
(author)
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Electrochemical characterisation of mixed monolayer assemblies of thiol analogues of cholesterol and fatty acids on gold
- 1997
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In: Journal of Electroanalytical Chemistry. - : Elsevier Science B.V., Amsterdam.. - 0022-0728 .- 1873-2569. ; 430:1-2, s. 189-195
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Journal article (peer-reviewed)abstract
- A self-assembled monolayer (SAM) on gold prepared from a binary mixture of a thiol analogue of cholesterol (thiocholesterol, TC) and a functionalised alkanethiol (11-mercaptoundecanoic acid, MUA) has been investigated by voltammetry. The voltammetric results are in agreement with previously reported spectroscopic data and show that the geometric arrangement and composition of the molecules in the mixed monolayer controls the heterogeneous electron transfer process of Fe(CN)(6)(3-) across the assembly. The quantitative description of the influence of TC on the electron transfer rate constant is given through Tafel plots. At the pure MUA SAM electrode, the electron transfer is governed by penetration through the monolayer. The introduction of TC into the SAMs creates defects giving rise to diffusion controlled electron transfer in addition to penetration. By raising the TC content the electron transfer rate constant increases due to diffusion, This behaviour can be explained by a model in which the assembly goes from a penetrative but defect-free film barrier (pure MUA SAM) via a structure with defects in the mixed composition regime to a defect-rich structure consisting of an array of ultramicroelectrodes (pure TC SAM). (C) 1997 Elsevier Science S.A.
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| 8. |
- Yang, Zhongping, et al.
(author)
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Preparation and characterization of mixed monolayer assemblies composed of thiol analogues of cholesterol and fatty acid
- 1997
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In: Langmuir. - : American Chemical Society. - 0743-7463 .- 1520-5827. ; 13:12, s. 3210-3218
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Journal article (peer-reviewed)abstract
- Mixed self-assembled monolayers provide an attractive model system for investigating the role of different molecules in biological membranes. This paper describes the preparation and characterization of a novel type of mixed monolayer assemblies composed of thiol analogues of cholesterol and fatty acid. The mixed: monolayers are prepared by coadsorbing 11-mercaptoundecanoic acid (MUA) and thiocholesterol(cholest-5-ene-3 beta-thiol, TC) from solution directly onto evaporated gold surfaces. The influence of TC on the molecular composition and conformation in the mixed monolayer is analyzed by using a combination of infrared reflection-absorption spectroscopy (IRAS), X-ray photoelectron spectroscopy (XPS), ellipsometry, contact angle measurement, and cyclic voltammetry. The results indicate that the TC molecules maintain their conformation in the mixed monolayers, whereas the MUA molecules display a significantly more disordered conformation as compared to the MUA molecules in the pure monolayer. Cyclic voltammetry shows that the mixed monolayers are more densely packed and less permeable than the pure TC and MUA monolayers. The kinetics of the coadsorption of TC and MUA from ethanol indicates that adsorption of TC initially is strongly preferred over MUA but that MUA dominates over TC at long coadsorption times. This is because there is a larger energy gain per unit area in forming monolayers with MUA, Further, it is also seen that the number of molecules per unit area changes with the molecular composition, as a consequence of the different sizes of TC and MUA. We present herein a method for calculating the mole fraction of TC on the gold surface, (chi TC), which accounts for this variation. As a consequence of the dissimilar size and shape of the two molecules, the wetting properties of the mixed monolayer are found to be mainly governed by the fractional area of TC, rather than by the molecular composition of TC, (chi TC).
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