Ni/Ni₃C Core/Shell Hierarchical Nanospheres with Enhanced Electrocatalytic Activity for Water Oxidation

Developing efficient and low-cost catalysts with high activity and excellent electrochemical and structural stability toward the oxygen evolution reaction (OER) is of great significance for both energy and environment sustainability. Herein, Ni/Ni₃C core/shell hierarchical nanospheres have been in situ synthesized via an ionic liquid-assisted hydrothermal method at relatively low temperature. Ionic liquid 1-butyl-3-methylimidazolium acetate has played multiple roles in the whole synthesis process. Benefiting from the high electrical conductivity, more exposed active sites and the core/shell interface effect, the obtained Ni/Ni₃C core/shell hierarchical nanospheres exhibit an outstanding OER performance with lower overpotential, small Tafel slope, and excellent stability. This fundamental method and insights with in situ coupling high conductivity metal support and metal carbide in a core/shell nanoarchitecture by an ionic liquid-assisted hydrothermal method would open up a new pathway to achieve high-performance electrocatalysts toward the OER

Novel Synthesis Strategy of γ‑AlOOH Nanotubes: Coupling Reaction via Ionic Liquid-Assisted Hydrothermal Route

A novel synthetic strategy, i.e., transition metal ions used to drive a coupling reaction in terms of complex formation of the metal ions and decomposition of a precursor, combined with ionic liquid-assisted hydrothermal route, was utilized to synthesize γ-AlOOH nanotubes with high purity and uniform dimension at a mild condition. These γ-AlOOH nanotubes can be easily transformed to γ-Al₂O₃ nanotubes by calcining at 600 °C for 2 h, without changing the morphology. More specifically, this strategy may be helpful to develop a new opportunity for synthesis of inorganic nanomaterials with novel morphologies and improved properties

Knockdown of GAPDH attenuates Mst1 activation and cell apoptosis in response to hypoxia/reoxygenation.

<p><b>A</b>, NRVMs were transfected with either control siRNA or GAPDH siRNA. 72 hours after transfection, cells were treated with hypoxia for 12 hours and reoxygenation for 24 hours. Mst1 was then immunoprecipitated and its activity was determined by an in vitro kinase assay using histone H2B as a substrate. <b>B</b>, NRVMs were transfected with either control siRNA or GAPDH siRNA. 72 hours after transfection, cells were treated with hypoxia/reoxygenation and the cell apoptosis was determined by using the TUNEL staining kit (Roche). Values are means ± SEM obtained from 4 experiments.</p

TSP-1 inhibited late EPCs tubule formation on Matrigel.

<p>(A) Late EPCs were plated on Matrigel with TSP-1 at different concentrations for 8 hrs (Scale bar = 200 µm, 100×magnification). (B) Quantification of total tube length per high power field (HPF, 100×magnification) was presented as mean±S.D. of three independent experiments (#p<0.05 versus no TSP-1 intervention, *p<0.01 versus no TSP-1 intervention).</p

Flow cytometric analysis of CD34+ cells and morphological and immunophenotypical characterization of early and late EPCs.

<p>(A) Flow cytometric analysis of CD34 expression after isolation by anti-CD34 microbeads. Shown are representative data from 3 independent experiments using cells isolated from different cord blood with similar results. Isotype controls are used. (B) Early EPCs cultured for 7 days and late EPCs cultured for 14 days (Scale bar = 100 µm, 200×magnification). (C)Early EPCs are shown to uptake DiI-Ac-LDL(red) (Scale bar = 100 µm, 200×magnification). Immunocytochemistry of VEGFR2(red),CD31 (red), and DAPI(blue) was demonstrated in early EPCs (Scale bar = 50 µm,400×magnification). (D) Immunocytochemistry of VEGFR2(red), vWF(green), CD31(red),and DAPI(blue) was demonstrated in late EPCs(Scale bar = 50 µm,400×magnification). Shown are representative data from 3 independent experiments using early EPCs isolated from different cord blood and 3 independent experiments using late EPCs isolated from different cord blood.</p

Knockdown of GAPDH attenuates Mst1 activation and cell apoptosis in response to chelerythrine.

<p>A, Total RNA extracted from control siRNA (siCTL) and GAPDH siRNA transfected cells was analyzed for the expression of GAPDH in NRCMs by qRT-PCR. B, NRVMs were transfected with either control siRNA or GAPDH siRNA. 72 hours after transfection, cell lysates were then subjected to western blot analysis to detect the expression of GAPDH. C, NRVMs were transfected with either control siRNA or GAPDH siRNA. 72 hours after transfection, cells were treated with chelerythrine (5 µM) for 2 hours. Mst1 was then immunoprecipitated and its activity was determined by an in vitro kinase assay using histone H2B as a substrate. D, NRVMs were transfected with either control siRNA or GAPDH siRNA. 24 hours after siRNA transfection, cells were then transduced with either Ad-LacZ or Ad-Mst1 (MOI = 50). 48 hours after virus transduction, NRVMs were treated with chelerythrine (5 µM) for 2 hours and the cell apoptosis was determined by using the TUNEL staining kit (Roche). Values are means ± SEM obtained from 4 experiments.</p

CD47 antibody attenuated TSP-1′s inhibition on angiogenesis of late EPCs.

<p>(A) Late EPCs were plated on Matrigel and treated with anti-CD47 antibody (2.5 µg/ml), anti-integrin β1 antibody (2 µg/ml) or control IgG for 30 min and then treated with TSP-1(2 µg/ml) as described (Scale bar = 400 µm, 50×magnification). (B) Total tube length per HPF (100×magnification) was measured. Values are presented as the mean±S.D. of three independent experiments (#p<0.05 versus control siRNA with TSP-1 stimulation)</p

TSP-1 inhibits VEGF induced VEGFR2 phosphorylation through CD47.

<p>(A) Late EPCs were treated with VEGF (25 ng/ml) for 0, 5, 10, 15 min respectively. Total protein was extracted and the expression of FLK-1, phospho-VEGFR2 (Tyr1175) was determined by Western blot. (B)Seventy-two hrs after transfection of CD47-specific siRNA or control siRNA, the expression of CD47 in late EPCs was determined by western blotting analysis in three independent experiments (#p<0.05 versus control siRNA). (C)Seventy-two hrs after transfection of CD47-specific siRNA or control siRNA, late EPCs were treated with TSP-1(2 µg/ml) for 30 min and then VEGF(25 ng/ml) for 5 min. Total protein was extracted and the expression of FLK-1, phospho-VEGFR2 (Tyr1175) was determined by Western blot analysis. (D) Quantification of VEGFR2 phosphorylation normalized to VEGFR2 in three independent experiments(#p<0.05 versus control siRNA, *p<0.01 versus control siRNA).</p

Phosphorylation of GAPDH by Mst1.

<p>A, 0.1 µg active Mst1 was incubated with different amounts of recombinant GAPDH for 60 min in the presence of ³²P-ATP in an <i>in vitro</i> phosphorylation assay. B, 0.1 µg active Mst1 was incubated with 4 µg bacterially expressed recombinant GAPDH for different time points in the presence of ³²P-ATP in an <i>in vitro</i> phosphorylation assay. Phosphorylation was detected by autoradiography. The data are representatives of 4 independent experiments.</p

Identification of Mst1 and GAPDH interaction sites.

<p><i>A,</i> schematic representation of Mst1 deletion mutants. <i>B,</i> flag-GAPDH expression vector in combination of either empty vector or expression vectors of Myc-Mst1 mutants were cotransfected into HEK293T cells. Extracted proteins were precipitated by anti-Myc antibody and then separated by 12% SDS-PAGE. The transferred membrane was immunoblotted with either HRP-conjugated anti-FLAG or HRP-conjugated anti-Myc antibody. Lysates were also immunoblotted with anti-Flag antibody to show the expression levels of Flag-GAPDH in HEK293T cells. <i>C,</i> schematic representation of GAPDH deletion mutants. <i>D,</i> Flag-Mst1 expression vector in combination of either empty vector or expression vectors of Myc-GAPDH mutants were cotransfected into HEK293T cells. Extracted proteins were precipitated by anti-Myc antibody and then separated by 12% SDS-PAGE. The transferred membrane was immunoblotted with either HRP-conjugated anti-FLAG or HRP-conjugated anti-Myc antibody. Lysates were also immunoblotted with anti-Flag antibody to show the expression of Flag-Mst1 in HEK293 cells.</p