COMP promotes pancreatic fibrosis by activating pancreatic stellate cells through CD36-ERK/AKT signaling pathways.

BACKGROUND: Pancreatic fibrosis is one of the most important pathological features of chronic pancreatitis (CP) and pancreatic stellate cells (PSCs) are the key cells of fibrosis. As an extracellular matrix (ECM) glycoprotein, cartilage oligomeric matrix protein (COMP) is critical for collagen assembly and ECM stability and recent studies showed that COMP exert promoting fibrosis effect in the skin, lungs and liver. However, the role of COMP in activation of PSCs and pancreatic fibrosis remain unclear. We aimed to investigate the role and specific mechanisms of COMP in regulating the profibrotic phenotype of PSCs and pancreatic fibrosis. METHODS: ELISA method was used to determine serum COMP in patients with CP. Mice model of CP was established by repeated intraperitoneal injection of cerulein and pancreatic fibrosis was evaluated by Hematoxylin-Eosin staining (H&E) and Sirius red staining. Immunohistochemical staining was used to detect the expression changes of COMP and fibrosis marker such as α-SMA and Fibronectin in pancreatic tissue of mice. Cell Counting Kit-8, Wound Healing and Transwell assessed the proliferation and migration of human pancreatic stellate cells (HPSCs). Western blotting, qRT-PCR and immunofluorescence staining were performed to detect the expression of fibrosis marker, AKT and MAPK family proteins in HPSCs. RNA-seq omics analysis as well as small interfering RNA of COMP, recombinant human COMP (rCOMP), MEK inhibitors and PI3K inhibitors were used to study the effect and mechanism of COMP on activation of HPSCs. RESULTS: ELISA showed that the expression of COMP significantly increased in the serum of CP patients. H&E and Sirius red staining analysis showed that there was a large amount of collagen deposition in the mice in the CP model group and high expression of COMP, α-SMA, Fibronectin and Vimentin were observed in fibrotic tissues. TGF-ß1 stimulates the activation of HPSCs and increases the expression of COMP. Knockdown of COMP inhibited proliferation and migration of HPSCs. Further, RNA-seq omics analysis and validation experiments in vitro showed that rCOMP could significantly promote the proliferation and activation of HPSCs, which may be due to promoting the phosphorylation of ERK and AKT through membrane protein receptor CD36. rCOMP simultaneously increased the expression of α-SMA, Fibronectin and Collagen I in HPSCs. CONCLUSION: In conclusion, this study showed that COMP was up-regulated in CP fibrotic tissues and COMP induced the activation, proliferation and migration of PSCs through the CD36-ERK/AKT signaling pathway. COMP may be a potential therapeutic candidate for the treatment of CP. Interfering with the expression of COMP or the communication between COMP and CD36 on PSCs may be the next direction for therapeutic research.

Overexpression of mitogen-activated protein kinase phosphatase-1 in endothelial cells reduces blood-brain barrier injury in a mouse model of ischemic stroke.

Ischemic stroke can cause blood-brain barrier (BBB) injury, which worsens brain damage induced by stroke. Abnormal expression of tight junction proteins in endothelial cells (ECs) can increase intracellular space and BBB leakage. Selective inhibition of mitogen-activated protein kinase, the negative regulatory substrate of mitogen-activated protein kinase phosphatase (MKP)-1, improves tight junction protein function in ECs, and genetic deletion of MKP-1 aggravates ischemic brain injury. However, whether the latter affects BBB integrity, and the cell type-specific mechanism underlying this process, remain unclear. In this study, we established an adult male mouse model of ischemic stroke by occluding the middle cerebral artery for 60 minutes and overexpressed MKP-1 in ECs on the injured side via lentiviral transfection before stroke. We found that overexpression of MKP-1 in ECs reduced infarct volume, reduced the level of inflammatory factors interleukin-1ß, interleukin-6, and chemokine C-C motif ligand-2, inhibited vascular injury, and promoted the recovery of sensorimotor and memory/cognitive function. Overexpression of MKP-1 in ECs also inhibited the activation of cerebral ischemia-induced extracellular signal-regulated kinase (ERK) 1/2 and the downregulation of occludin expression. Finally, to investigate the mechanism by which MKP-1 exerted these functions in ECs, we established an ischemic stroke model in vitro by depriving the primary endothelial cell of oxygen and glucose, and pharmacologically inhibited the activity of MKP-1 and ERK1/2. Our findings suggest that MKP-1 inhibition aggravates oxygen and glucose deprivation-induced cell death, cell monolayer leakage, and downregulation of occludin expression, and that inhibiting ERK1/2 can reverse these effects. In addition, co-inhibition of MKP-1 and ERK1/2 exhibited similar effects to inhibition of ERK1/2. These findings suggest that overexpression of MKP-1 in ECs can prevent ischemia-induced occludin downregulation and cell death via deactivating ERK1/2, thereby protecting the integrity of BBB, alleviating brain injury, and improving post-stroke prognosis.

Puerarin Ameliorates Caerulein-Induced Chronic Pancreatitis via Inhibition of MAPK Signaling Pathway.

Pancreatic fibrosis is one of the most important pathological features of chronic pancreatitis (CP), and pancreatic stellate cells (PSCs) are considered to be the key cells. Puerarin is the most important flavonoid active component in Chinese herb Radix Puerariae, and it exhibited anti-fibrotic effect in various fibrous diseases recently. However, the impact and molecular mechanism of puerarin on CP and pancreatic fibrosis remain unknown. This study systematically investigated the effect of puerarin on CP and pancreatic fibrosis in vivo and in vitro. H&E staining, Sirius Red staining, qRT-PCR and Western blotting analysis of fibrosis and inflammation related genes of pancreatic tissues showed that puerarin notably ameliorated pancreatic atrophy, inflammation and fibrosis in a model of caerulein-induced murine CP. Western blotting analysis of pancreatic tissues showed the phosphorylation level of MAPK family proteins (JNK1/2, ERK1/2 and p38 MAPK) significantly increased after modeling of cerulein, while puerarin could inhibit their phosphorylation levels to a certain extent. We found that puerarin exerted a marked inhibition on the proliferation, migration and activation of PSCs, determined by CCK-8 assay, transwell migration assay, scratch wound-healing assay and expression levels of α-SMA, Fibronectin, Col1α1 and GFAP. Western blotting result demonstrated that puerarin markedly inhibited the phosphorylation of MAPK family proteins (JNK1/2, ERK1/2 and p38 MAPK) of PSCs in a dose-dependent manner whether or not stimulated by platelet-activating factor. In conclusion, the present study showed that puerarin could be a potential therapeutic candidate in the treatment of CP, and the MAPK pathway might be its important target.

Antimony tin oxide/lead selenide composite as efficient counter electrode material for quantum dot-sensitized solar cells.

Antimony tin oxide (ATO)/lead selenide (PbSe) composite was rationally designed and fabricated on fluorine doped tin oxide glass (FTO) for using as counter electrode (CE) of quantum dot sensitized solar cells (QDSSCs). The electrocatalytic activity of the CE is deeply investigated in the polysulfide electrolyte by employing the Tafel, electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) of the symmetrical cells. The results confirm that the ATO/PbSe CE has better electrocatalytic activity and stability than that of PbSe CE obtained by pulse voltage electrodeposition (PVD). The enhanced electrocatalytic performance of ATO/PbSe CE can be attributed to its high specific surface area, excellent permeability, conductivity and interface connectivity, which provide more electrocatalytic active sites for the reduction of polysulfide species, as well as fast channels for ions diffusion and electron transport. As a result, the CdS QDSSCs and CdS/CdSe co-sensitized QDSSCs assembled by the ATO/PbSe CE exhibits better power conversion efficiency (η) of 1.72% and 5.59%, respectively than that of PbSe CE obtained by PVD. Furthermore, photovoltaic property of the ATO/PbSe CE in CdS/CdSe co-sensitized QDSSCs keeps stable for over 200 min. This present work provides a simple and effective strategy for the construction of high-performance CE materials of QDSSCs.

Voltage-assisted SILAR deposition of CdSe quantum dots to construct a high performance of ZnS/CdSe/ZnS quantum dot-sensitized solar cells.

The charge recombination on the interfaces of TiO2/quantum dots (QDs)/electrolyte is a key factor limiting the efficiency of quantum dot-sensitized solar cells (QDSSCs). Construction of double-layer barrier structure of ZnS/QDs/ZnS is a vital strategy to suppress the interfacial charge recombination. However, a large lattice mismatch (12%) at CdSe/ZnS interfaces causes CdSe to grow slowly on TiO2/ZnS mesoporous film, weakening the interaction between QDs and mesoporous film, which reducing the efficiency of CdSe QDSSCs with double ZnS barrier layers. Applying a voltage of 2 V in successive ionic layer adsorption reaction (VASILAR) to create an electric field, which assists Cd2+ and SeSO32- ions rapidly diffuse into the TiO2/ZnS mesoporous film to react forming CdSe QDs at room temperature. Optimizing the number of CdSe QDs deposition layers and combine with ZnS double-layer barrier structure, a best PCE of 4.34% for ZnS/CdSe/ZnS QDSSCs is achieved. This study gives a fast and simple approach to inhibit interfacial charge recombination to construct high performance CdSe QDSSCs.

Bisulfone-Functionalized Organic Polymer Photocatalysts for High-Performance Hydrogen Evolution.

Conjugated polymers show great potential in the application of photocatalysis, particularly for the photoreduction reaction of water to generate hydrogen. Molecular structure design is a key part for building a high-performance organic photocatalyst. Herein, two bisulfone-containing conjugated polymer photocatalysts were constructed with 1D or 3D polymer structures, and the effect of polymer geometry on photocatalytic activity was studied. It was found that the linear polymer PySEO-1 exhibited increased photocatalytic performance compared with the 3D polymer network PySEO-2 because the enhanced coplanarity of the polymeric chain in PySEO-1 promoted the photogenerated charge-carrier transmission along the 1D main chain. As a result, an attractive hydrogen generation rate of 9477 µmol h-1 g-1 was obtained with PySEO-1 under broadband light irradiation. PySEO-1 also exhibited a high external quantum efficiency of 4.1 % at an incident light wavelength of 400 nm, demonstrating that the bisulfone-containing polymers are attractive as organic photocatalysts for hydrogen production.

Co nanoparticles supported on three-dimensionally N-doped holey graphene aerogels for electrocatalytic oxygen reduction.

The reactive and stable catalysts for the oxygen reduction reaction are highly desirable for low temperature fuel cells. The commercial oxygen reduction reaction electrocatalysts generally reply on noble metal based nanomaterials, which suffer from inherent cost and selectivity issues. At present, it still remains challenge for designing efficient non-noble metal-based oxygen reduction reaction electrocatalysts. Herein, we successfully synthesize Co nanoparticles supported on three-dimensionally N-doped holey graphene aerogels hybrids by the high-temperature calcination of the graphene aerogels-polyallylamine-CoII hybrids. The component optimized hybrids show the excellent electrocatalytic activity for oxygen reduction reaction in alkaline media, which is comparable to commercial Pt/C electrocatalyst. Meanwhile, the hybrids also show eminent tolerance for CO and methanol, attributing to their excellent oxygen reduction reaction selectivity. The three-dimensionally interconnected structure of graphene aerogels, N-doping, uniform dispersion and high crystallinity of Co nanoparticles, and holey structure of graphene contribute to the striking oxygen reduction reaction activity of hybrids.

Conjugated Microporous Polymers with Tunable Electronic Structure for High-Performance Potassium-Ion Batteries.

Conjugated microporous polymers (CMPs) with π-conjugated skeletons show great potential as energy storage materials due to their porous structure and tunable redox nature. However, CMPs and the structure-performance relationships have not been well explored for potassium-ion batteries (KIBs). Here, we report the structure-engineered CMP anodes with tunable electronic structures for high-performance KIBs. The results demonstrate that the electronic structure of the CMPs plays an important role in enhancing potassium storage capability, including the lowest unoccupied molecular orbital (LUMO) distribution, LUMO energy level, and band gap, which can be finely tuned by synthetic control. It was revealed that the poly(pyrene- co-benzothiadiazole) (PyBT) with optimized structure delivers a high reversible capacity of 428 mAh g-1 and shows an excellent cycling stability over 500 cycles. Our findings provide a fundamental understanding in the design of CMP anode materials for high-performance potassium-organic energy storage devices.

Bimetallic Platinum-Rhodium Alloy Nanodendrites as Highly Active Electrocatalyst for the Ethanol Oxidation Reaction.

Rationally designing and manipulating composition and morphology of precious metal-based bimetallic nanostructures can markedly enhance their electrocatalytic performance, including selectivity, activity, and durability. We herein report the synthesis of bimetallic PtRh alloy nanodendrites (ANDs) with tunable composition by a facile complex-reduction synthetic method under hydrothermal conditions. The structural/morphologic features, formation mechanism, and electrocatalytic performance of PtRh ANDs are investigated thoroughly by various physical characterization and electrochemical methods. The preformed Rh crystal nuclei effectively catalyze the reduction of Pt2+ precursor, resulting in PtRh alloy generation due to the catalytic growth and atoms interdiffusion process. The Pt atoms deposition distinctly interferes in Rh atoms deposition on Rh crystal nuclei, resulting in dendritic morphology of PtRh ANDs. For the ethanol oxidation reaction (EOR), PtRh ANDs display the chemical composition and solution pH co-dependent electrocatalytic activity. Because of the alloy effect and particular morphologic feature, Pt1Rh1 ANDs with optimized composition exhibit better reactivity and stability for the EOR than commercial Pt nanocrystals electrocatalyst.

A facile synthesis to Zn(2)SiO(4):Mn(2+) phosphor with controllable size and morphology at low temperature.

Sphere- and rod-shaped Zn(2)SiO(4):Mn(2+) phosphor nanocrystals were synthesized at 230 degrees C. The process consists of tuning the surfactant concentration in the oil/surfactant/ethanol system. Powder X-ray (XRD) and transmission electron microscopy (TEM) were used to characterize the phase purity, size and morphology. Photoluminescent (PL) spectra were collected and analyzed. Fourier transform infrared (FT-IR) spectra of the samples indicate the removal of surfactant in the phosphor nanoparticles. As a result, the sphere-shaped phosphor nanoparticles of 100 nm in size can be redispersed in ethanol ultrasonically. The suspension maintain stable for over 48 h.

Ultrathin Rhodium Oxide Nanosheet Nanoassemblies: Synthesis, Morphological Stability, and Electrocatalytic Application.

Inspired by graphene, ultrathin two-dimensional nanomaterials with atomic thickness have attracted more and more attention because of their unique physicochemical properties and electronic structure. In this work, the atomically thick ultrathin Rh2O3 nanosheet nanoassemblies (Rh2O3-NSNSs) were obtained by oxidizing the atomically thick ultrathin Rh nanosheet nanoassemblies with HClO. For the first time, Rh-based nanostructures were used as the oxygen evolution reaction (OER) electrocatalyst in an alkaline medium. Surprisingly, the as-prepared Rh2O3-NSNSs displayed extremely improved catalytic activity and durability for the OER compared with those of the commercial Ir/C catalyst and most recently reported Ir-based electrocatalysts. The result indicated Rh-based nanostructures that have great promise to become a potential candidate for efficient OER electrocatalyst because of the similarity of Rh and Ir prices. These experimental results demonstrated the reasonable morphological control of Rh2O3 nanostructures could significantly improve their catalytic activity and durability during heterogeneous catalysis.

Sulfur in Hyper-cross-linked Porous Polymer as Cathode in Lithium-Sulfur Batteries with Enhanced Electrochemical Properties.

Sulfur was impregnated into hyper-cross-linked porous polymer (HCP) with a high specific area and unique porous structure. Compared to its inorganic or carbon counterparts, the HCP has a relatively high specific surface area of 1980 m2 g-1 with a total pore volume of 2.61 cm3 g-1, resulting in sulfur content in HCP/S of as high as 80 wt %. As a benefit of the unique HCP structure, the HCP/S composite exhibits a high initial discharge specific capacity (1333 mA h g-1 at 0.2 C), high-rate property, and good cycling stability (658 mA h g-1 after 120 cycles at 0.5 C and 604 mA h g-1 after 80 cycles at 1 C). Furthermore, the capacity of cells loses less than 1% after the first 20 charge/discharge cycles, while the HCP/S cathode can be cycled with an excellent Coulombic efficiency of above 94% after 120 cycles. Compared with pristine sulfur, the superior electrochemical performance of HCP/S composite is related to the cross-linked porous framework. Such structure could provide short ionic/electronic conduction pathways and suppress the polysulfide shuttle during the discharge process.

Synthesis of complex rare earth fluoride nanocrystal phosphors.

Complex rare earth fluoride (NaRF(4), R = Ce,Y,Gd) nanocrystals of 30-50 nm were synthesized by hydrothermal and solvothermal techniques. The size, morphology and phase transition of the complex rare earth fluorides are discussed as the effects of different solvents, reaction time and temperature. Hexagonal phase NaRF(4) nanocrystals with good dispersibility can be prepared in the presence of EDTA using ethanol as the solvent. After doping with Yb(3+), Er(3+); Yb(3+), Tm(3+), and Eu(3+), some typical up-conversion and down-conversion photoluminescence was characterized and discussed.

Hydrothermal Synthesis and Catalytic Application of Ultrathin Rhodium Nanosheet Nanoassemblies.

Ultrathin noble metal nanosheets with atomic thickness exhibit abnormal electronic, surfacial, and photonic properties due to the unique two-dimensional (2D) confinement effect, which have attracted intensive research attention in catalysis/electrocatalysis. In this work, the well-defined ultrathin Rh nanosheet nanoassemblies with dendritic morphology are synthesized by a facile hydrothermal method with assistance of poly(allylamine hydrochloride) (PAH), where PAH effectively acts as the complexant and shape-directing agent. Transmission electron microscopy and atomic force microscopy images reveal the thickness of 2D Rh nanosheet with (111) planes is only ca. 0.8-1.1 nm. Nitrogen adsorption-desorption measurement displays the specific surface area of the as-prepared ultrathin Rh nanosheet nanoassemblies is 139.4 m2 g-1, which is much bigger than that of homemade Rh black (19.8 m2 g-1). Detailed catalytic investigations display the as-prepared ultrathin Rh nanosheet nanoassemblies have nearly 20.4-fold enhancement in mass-activity for the hydrolysis of ammonia borane as compared with homemade Rh black.

One-Pot Fabrication of Hollow and Porous Pd-Cu Alloy Nanospheres and Their Remarkably Improved Catalytic Performance for Hexavalent Chromium Reduction.

Noble metal nanostructures (NMNSs) play a crucial role in many heterogeneous catalytic reactions. Hollow and porous NMNSs possess generally prominent advantages over their solid counterparts due to their unordinary structural features. In this work, we describe a facial one-pot synthesis of hollow and porous Pd-Cu alloy nanospheres (Pd-Cu HPANSs) through a polyethylenimine (PEI)-assisted oxidation-dissolution mechanism. The strong coordination interaction between CuII and PEI facilitates the oxidation-dissolution of the Cu2O nanospheres template under air conditions, which is responsible for the generation of the Pd-Cu alloy and the convenient removal of the Cu2O nanospheres template at room temperature. Compared to the commercial Pd black, the Pd-Cu HPANSs show remarkably improved catalytic activity for the reduction of K2Cr2O7 by HCOOH at room temperature, attributing to the enhanced catalytic activity of the Pd-Cu HPANSs for the dehydrogenation decomposition of HCOOH.

Stable, High-Efficiency Pyrrolidinium-Based Electrolyte for Solid-State Dye-Sensitized Solar Cells.

We synthesized a series of pyrrolidinium based dicationic ionic crystals with high melting point and good thermal stability. Research on the crystal structure shows that there are ordered three-dimensional ionic channels in these crystals which is favorable for the ionic conductor to achieve high conductivity and diffusion coefficient. These ionic crystals are applied to electrolyte as matrix in dye sensitized solar cells, and the influence of crystal structure (including the alkylene chain separating two pyrrolidinium rings and anion) versus the device performances are studied by steady-state voltammography, current-voltage trace, and electrochemical impedance spectroscopy. As the solid state electrolyte, an optimized efficiency of 6.02% have achieved under full sunlight irradiation using ionic crystal [C6BEP][TFSI]2. And the device based on this solid electrolyte shows the excellent long-term stability, maintaining 92% of the initial efficiency after 960 h. This study elucidates fundamental the structure of dicationic crystal and provide useful clues for further improvement of solid-state electrolytes in DSSC.

Effective solid electrolyte based on benzothiazolium for dye-sensitized solar cells.

Thiaozole/benzothiaozole-based dicationic conductors were synthesized and applied as solid-state electrolyte in dye-sensitized solar cells (DSSCs). X-ray diffraction, scanning electron microscopy, thermal gravimetric analysis, steady-state voltammogram, photocurrent intensity-photovoltage test, and electrochemical impedance spectroscopy are used to characterize the materials and the mechanism of the cell performance. Compared to the traditional monocationic crystals, the dicationic crystals have a larger size and can provide more opportunities to fine-tune their physical/chemical properties. As a consequence, this solid-state electrolyte-based DSSC achieved photoelectric conversion efficiency of 7.90% under full air-mass (AM 1.5) sunlight (100 mW·cm(-2)).

Micrometer-sized fluorine doped tin oxide as fast electron collector for enhanced dye-sensitized solar cells.

Titanium dioxide (TiO2)-layered fluorine doped tin oxide (FTO) powder was synthesized and applied as the photoanode in dye-sensitized solar cells (DSSCs). FTO powders are connected to form a direct electron pathway for the efficient extract of injected electrons, while the TiO2 layer serves as an energy barrier prohibiting the charge combination with oxidized dye or I3(-). The electrochemical impedance spectroscopy (EIS) analyses suggest that electrons have a longer combination lifetime (τe = 233 ms) than that of the electron in the DSSCs using traditional P25 photoanodes (τe = 28 ms). The DSSCs using 5 µm thick TiO2@FTO as photoanodes eventually give a respectable and long-term stable photovoltaic performance with a current density of 23.8 mA/cm(2), an open circuit voltage of 0.69 V, and power conversion efficiency of 7.4%. The results are received on a low dye loading level (0.25 × 10(-7) mol/cm(2)), which is (1)/10 of that for traditional photoanode (2.79 × 10(-7) mol/cm(2)).