Improving the catalytic efficiency of platinum for the hydrogen evolution reaction is valuable for water splitting technologies. Hydrogen spillover has emerged as a new strategy in designing binary-component Pt/support electrocatalysts. However, such binary catalysts often suffer from a long reaction pathway, undesirable interfacial barrier, and complicated synthetic processes. Here we report a single-phase complex oxide La2Sr2PtO7+δ as a high-performance hydrogen evolution electrocatalyst in acidic media utilizing an atomic-scale hydrogen spillover effect between multifunctional catalytic sites. With insights from comprehensive experiments and theoretical calculations, the overall hydrogen evolution pathway proceeds along three steps: fast proton adsorption on O site, facile hydrogen migration from O site to Pt site via thermoneutral La-Pt bridge site serving as the mediator, and favorable H2 desorption on Pt site. Benefiting from this catalytic process, the resulting La2Sr2PtO7+δ exhibits a low overpotential of 13 mV at 10 mA cm−2, a small Tafel slope of 22 mV dec−1, an enhanced intrinsic activity, and a greater durability than commercial Pt black catalyst.

With the increasing occurrence of vascular diseases and poor long-term patency rates of current small diameter vascular grafts, it becomes urgent to pursuit biomaterial as scaffold to mimic blood vessel morphologically and mechanically. In this study, novel human-like collagen (HLC, produced by recombinant E. coli)/chitosan tubular scaffolds were fabricated by cross-linking and freeze-drying process. The scaffolds were characterized by scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), and tensile test, respectively. Human venous fibroblasts were expanded and seeded onto the scaffolds in the density of 1 x 10(5) cells/cm(2). After a 15-day culture under static conditions, the cell-polymer constructs were observed using SEM, confocal laser scanning microscopy (CLSM), histological examination, and biochemical assays for cell proliferation and extracellular matrix production (collagen and glycosaminoglycans). Furthermore, the scaffolds were implanted into rabbits' livers to evaluate their biocompatibility. The results indicated that HLC/chitosan tubular scaffolds (1) exhibited interconnected porous structure; (2) achieved the desirable levels of pliability (elastic up to 30% strain) and stress of 300 +/- 16 kPa; (3) were capable of enhancing cell adhesion and proliferation and ECM secretion; (4) showed superior biocompatibility. This study suggested the feasibility of HLC/chitosan composite as a promising candidate scaffold for blood vessel tissue engineering.

The biodegradability, histocompatibility and biocompatibility of injectable HCD hydrogels were determined throughin vitroandin vivotests.

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Novel human-like collagen (HLC)/chitosan hybrid scaffolds were fabricated at blend ratios of 0%, 0.02%, 0.2% by crosslinking and freeze-drying process. The properties of the scaffolds were investigated, including morphology, mechanical strength, degradability, and cell biocompatibility. When the blend ratio was 0.02%, the morphology of the scaffolds was highly homogeneous with interconnected porous structure 46 AE 9 mm in size (SEM). The X-ray photoelectron spectroscopy analysis indicated intermolecular crosslinks between HLC and chitosan. The strain and stress of the scaffolds were 37.9 AE 3.3% and 309.7 AE 19.7 KPa, respectively. Human venous fibroblasts were expanded and seeded into the scaffolds in the density of 1 Â 10 5 cells/cm 3 under static conditions. The cell morphology and proliferation were investigated using SEM, H&E, and MTT assay, which showed that the optimal content of the chitosan was signifcantly enhanced the cells adhesion, proliferation, and viability, compared to pure HLC, pure chitosan, and 0.2% chitosan/HLC scaffolds. These hybrid scaffolds appear to have favorable characteristics for vascular tissue engineering application.

BackgroundCombining experimental and computational screening methods has been of keen interest in drug discovery. In the present study, we developed an efficient screening method that has been used to screen 2100 small-molecule compounds for alanine racemase Alr-2 inhibitors.ResultsWe identified ten novel non-substrate Alr-2 inhibitors, of which patulin, homogentisic acid, and hydroquinone were active against Aeromonas hydrophila. The compounds were found to be capable of inhibiting Alr-2 to different extents with 50% inhibitory concentrations (IC50) ranging from 6.6 to 17.7 μM. These compounds inhibited the growth of A. hydrophila with minimal inhibitory concentrations (MICs) ranging from 20 to 120 μg/ml. These compounds have no activity on horseradish peroxidase and d-amino acid oxidase at a concentration of 50 μM. The MTT assay revealed that homogentisic acid and hydroquinone have minimal cytotoxicity against mammalian cells. The kinetic studies indicated a competitive inhibition of homogentisic acid against Alr-2 with an inhibition constant (K i) of 51.7 μM, while hydroquinone was a noncompetitive inhibitor with a K i of 212 μM. Molecular docking studies suggested that homogentisic acid binds to the active site of racemase, while hydroquinone lies near the active center of alanine racemase.ConclusionsOur findings suggested that combining experimental and computational methods could be used for an efficient, large-scale screening of alanine racemase inhibitors against A. hydrophila that could be applied in the development of new antibiotics against A. hydrophila.Electronic supplementary materialThe online version of this article (doi:10.1186/s12866-017-1010-x) contains supplementary material, which is available to authorized users.

In this study, we designed multifunctionalized hydrogel scaffolds and injectable particles based on highmolecular-weight (M W ) pullulan and human-like collagen (HLC) crosslinked with 1,4-butanediol diglycidyl ether (BDDE) for combination therapy tissue restoration. The properties of the pullulan/BDDE (PB) and pullulan/BDDE/human-like collagen (PBH) hydrogels were characterized via swelling ratio measurements, mechanical tests, and enzymatic degradation in vitro and via subcutaneous injections in vivo. The results demonstrate that the dry hydrogels completely returned to their original state in deionized water. The elastic modulus of the PBH53 dry hydrogels is higher than that of the other hydrogels after exposure to bending stress and compression stress with a maximum value of 7858.93 MPa. In addition, the in vitro live/dead staining and cell adhesion of the PBH hydrogels exhibited a superior fibroblast morphology without high levels of cell death, which were considerably better than those of PB hydrogels. In vivo, PB and PBH particles with good biocompatibility and anti-biodegradation were successfully prepared via the granulation of wet PB and PBH hydrogels for efficient subcutaneous injection in Kunming mice and New Zealand rabbits. Therefore, the PB and PBH hydrogels were found to be acceptable, safe, soft materials for use in skin restoration, cartilage treatment, and lacrimal dryness therapy. Fig. 3 Cross-sections of the PB and PBH hydrogels before and after degradation by pullulanase, collagenase I and pullulan/collagenase I, as observed by SEM. The first line denotes the cross-section for the four hydrogels (50Â), with a scale bar of 400 mm; the second line represents the cross-section for the four hydrogels at a higher magnification (100Â), with a scale bar of 200 mm; the third line represents the particles for the four hydrogels (100Â), with a scale bar of 200 mm; the fourth line denotes the cross-section for the four hydrogels after degradation by pullulanase (100Â), with a scale bar of 200 mm; the fifth line represents the cross-section for the four hydrogels after degradation by collagenase I (100Â), with a scale bar of 200 mm; and the sixth line denotes the cross-section for the four hydrogels after degradation by pullulanase/collagenase I (250Â), with a scale bar of 100 mm.Fig. 6 Cell adhesion adherent cells on the hydrogels. SEM images of fibroblast attachment on the PB10 hydrogel (A1-A3), PBH10 hydrogel (B1-B3), PB53 hydrogel (C1-C3) and PBH53 hydrogel (D1-D3) at 24 (A1, B1, C1 and D1), 48 (A2, B2, C2 and D2) and 72 h (A3, B3, C3 and D3); the scale bar is 10 mm. Journal of Materials Chemistry B Paper

High‐valent metal‐oxo (HVMO) species are powerful non‐radical reactive species that enhance advanced oxidation processes (AOPs) due to their long half‐lives and high selectivity towards recalcitrant water pollutants with electron‐donating groups. However, high‐valent cobalt‐oxo (CoIV=O) generation is challenging in peroxymonosulfate (PMS)‐based AOPs because the high 3d‐orbital occupancy of cobalt would disfavor its binding with a terminal oxygen ligand. Herein, we propose a strategy to construct isolated Co sites with unique N1O2 coordination on the Mn3O4 surface. The asymmetric N1O2 configuration is able to accept electrons from the Co 3d‐orbital, resulting in significant electronic delocalization at Co sites for promoted PMS adsorption, dissociation and subsequent generation of CoIV=O species. CoN1O2/Mn3O4 exhibits high intrinsic activity in PMS activation and sulfamethoxazole (SMX) degradation, highly outperforming its counterpart with a CoO3 configuration, carbon‐based single‐atom catalysts with CoN4 configuration, and commercial cobalt oxides. CoIV=O species effectively oxidize the target contaminants via oxygen atom transfer to produce low‐toxicity intermediates. These findings could advance the mechanistic understanding of PMS activation at the molecular level and guide the rational design of efficient environmental catalysts.