Publications by authors named "Xue-Jun Wu"

49 Publications

Preparation of CdS Se -MoS Heterostructures via Cation Exchange of Pre-Epitaxially Synthesized Cu S Se -MoS for Photocatalytic Hydrogen Evolution.

Small 2021 Feb 19:e2006135. Epub 2021 Feb 19.

Department of Chemistry, City University of Hong Kong, Hong Kong, China.

Construction of 2D transition metal dichalcogenide (TMD)-based epitaxial heterostructures with different compositions is important for various promising applications, including electronics, photonics, and catalysis. However, the rational design and controlled synthesis of such kind of heterostructures still remain challenge, especially for those consisting of layered TMDs and other non-layered materials. Here, a facile one-pot, wet-chemical method is reported to synthesize Cu S Se -MoS heterostructures in which two types of different epitaxial configurations, i.e., vertical and lateral epitaxies, coexist. The chalcogen ratio (S/Se) in Cu S Se and the loading amount of MoS in the heterostructures can be tuned. Impressively, the obtained Cu S Se -MoS heterostructures can be transformed to CdS Se -MoS without morphological change via cation exchange. As a proof-of-concept application, the obtained CdS Se -MoS heterostructures with controllable compositions are used as photocatalysts, exhibiting distinctive catalytic activities toward the photocatalytic hydrogen evolution under visible light irradiation. The method paves the way for the synthesis of different TMD-based lateral epitaxial heterostructures with unique properties for various applications.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/smll.202006135DOI Listing
February 2021

Rational Synthesis of 1D Hyperbranched Heterostructures with Enhanced Optoelectronic Performance.

Angew Chem Int Ed Engl 2021 Feb 15;60(7):3475-3480. Epub 2020 Dec 15.

State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023, P. R. China.

One-dimensional (1D) hyperbranched heterostructures (HBHSs) with abundant interfaces are rendered with various interfacial phenomena and functionalities. However, the rational synthesis of 1D HBHSs with desired spatial architecture and specific interface remains a great challenge. Here, we report a seeded growth method for controlled synthesis of two extraordinary types of HBHSs, in which high-intensity of CdS branches selectively grow on 1D nanowire (NW) trunks with different growth behaviors. The composition of the HBHSs can be further tuned by combining with cation exchange method, which enriches the variety of the HBHSs. The optoelectronic devices based on a single HBHS were fabricated and exhibit a better photoresponse performance compared with that of a single NW trunk. This advance provides a strategy for the controlled synthesis HBHSs with complex morphology and offers a platform for exploring their applications for photo harvesting and conversion.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/anie.202012537DOI Listing
February 2021

Tanshinone IIA Suppresses Hypoxia-induced Apoptosis in Medial Vestibular Nucleus Cells a Skp2/BKCa Axis.

Curr Pharm Des 2020 ;26(33):4185-4194

Department of Otolaryngology, Head and Neck Surgery, Shanghai General Hospital of Nanjing Medical University, Shanghai 200080, China.

Background: The aim of the present study was to investigate the protective effects of Tanshinone IIA (Tan IIA) on hypoxia-induced injury in the medial vestibular nucleus (MVN) cells.

Methods: An in vitro hypoxia model was established using MVN cells exposed to hypoxia. The hypoxia-induced cell damage was confirmed by assessing cell viability, apoptosis and expression of apoptosis-associated proteins. Oxidative stress and related indicators were also measured following hypoxia modeling and Tan IIA treatment, and the genes potentially involved in the response were predicted using multiple GEO datasets.

Results: The results of the present study showed that Tan IIA significantly increased cell viability, decreased cell apoptosis and decreased the ratio of Bax/Bcl-2 in hypoxia treated cells. In addition, hypoxia treatment increased oxidative stress in MVN cells, and treatment with Tan IIA reduced the oxidative stress. The expression of SPhase Kinase Associated Protein 2 (SKP2) was upregulated in hypoxia treated cells, and Tan IIA treatment reduced the expression of SKP2. Mechanistically, SKP2 interacted with large-conductance Ca2+-activated K+ channels (BKCa), regulating its expression, and BKCa knockdown alleviated the protective effects of Tan IIA on hypoxia induced cell apoptosis.

Conclusion: The results of the present study suggested that Tan IIA had a protective effect on hypoxia-induced cell damage through its anti-apoptotic and anti-oxidative activity via an SKP2/BKCa axis. These findings suggest that Tan IIA may be a potential therapeutic for the treatment of hypoxia-induced vertigo.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.2174/1381612826666200602144405DOI Listing
January 2021

Selective Epitaxial Growth of Oriented Hierarchical Metal-Organic Framework Heterostructures.

J Am Chem Soc 2020 May 1;142(19):8953-8961. Epub 2020 May 1.

Department of Chemistry, City University of Hong Kong, Hong Kong, China.

Metal-organic framework (MOF) heterostructures have shown promising applications in gas adsorption, gas separation, catalysis, and energy, arising from the synergistic effect of each component. However, owing to the difficulty in controlling the size, shape, nucleation, and growth of MOFs, it remains a great challenge to construct MOF heterostructures with precisely controlled orientation, morphology, dimensionality, and spatial distribution of each component. Here, we report a seeded epitaxial growth method to prepare a series of hierarchical MOF heterostructures by engineering the structures, sizes, dimensionalities, morphologies, and lattice parameters of both MOF seeds and the secondary MOFs. In these heterostructures, PCN-222 (also known as MOF-545) nanorods selectively grow along the major axis of the ellipsoid-like PCN-608 nanoparticles, on the two end facets of the hexagonal prism-like NU-1000 nanorods, and on the two basal planes of the hexagonal PCN-134 nanoplates, while Zr-BTB nanosheets selectively grow on the six edge facets of PCN-134 nanoplates. The selective epitaxial growth of MOFs opens the way to synthesize different hierarchical heterostructures with tunable architectures and dimensionalities, which could process various promising applications.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/jacs.0c02489DOI Listing
May 2020

Synthesis of Palladium-Based Crystalline@Amorphous Core-Shell Nanoplates for Highly Efficient Ethanol Oxidation.

Adv Mater 2020 May 6;32(21):e2000482. Epub 2020 Apr 6.

Department of Chemistry, City University of Hong Kong, Hong Kong, China.

Phase engineering of nanomaterials (PEN) offers a promising route to rationally tune the physicochemical properties of nanomaterials and further enhance their performance in various applications. However, it remains a great challenge to construct well-defined crystalline@amorphous core-shell heterostructured nanomaterials with the same chemical components. Herein, the synthesis of binary (Pd-P) crystalline@amorphous heterostructured nanoplates using Cu P nanoplates as templates, via cation exchange, is reported. The obtained nanoplate possesses a crystalline core and an amorphous shell with the same elemental components, referred to as c-Pd-P@a-Pd-P. Moreover, the obtained c-Pd-P@a-Pd-P nanoplates can serve as templates to be further alloyed with Ni, forming ternary (Pd-Ni-P) crystalline@amorphous heterostructured nanoplates, referred to as c-Pd-Ni-P@a-Pd-Ni-P. The atomic content of Ni in the c-Pd-Ni-P@a-Pd-Ni-P nanoplates can be tuned in the range from 9.47 to 38.61 at%. When used as a catalyst, the c-Pd-Ni-P@a-Pd-Ni-P nanoplates with 9.47 at% Ni exhibit excellent electrocatalytic activity toward ethanol oxidation, showing a high mass current density up to 3.05 A mg , which is 4.5 times that of the commercial Pd/C catalyst (0.68 A mg ).
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/adma.202000482DOI Listing
May 2020

Ag@MoS Core-Shell Heterostructure as SERS Platform to Reveal the Hydrogen Evolution Active Sites of Single-Layer MoS.

J Am Chem Soc 2020 Apr 3;142(15):7161-7167. Epub 2020 Apr 3.

Department of Chemistry, City University of Hong Kong, Hong Kong, China.

Understanding the reaction mechanism for the catalytic process is essential to the rational design and synthesis of highly efficient catalysts. MoS has been reported to be an efficient catalyst toward the electrochemical hydrogen evolution reaction (HER), but it still lacks direct experimental evidence to reveal the mechanism for MoS-catalyzed electrochemical HER process at the atomic level. In this work, we develop a wet-chemical synthetic method to prepare the single-layer MoS-coated polyhedral Ag core-shell heterostructure (Ag@MoS) with tunable sizes as efficient catalysts for the electrochemical HER. The Ag@MoS core-shell heterostructures are used as ideal platforms for the real-time surface-enhanced Raman spectroscopy (SERS) study owing to the strong electromagnetic field generated in the plasmonic Ag core. The in situ SERS results provide solid Raman spectroscopic evidence proving the S-H bonding formation on the MoS surface during the HER process, suggesting that the S atom of MoS is the catalytic active site for the electrochemical HER. It paves the way on the design and synthesis of heterostructures for exploring their catalytic mechanism at atomic level based on the in situ SERS measurement.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/jacs.0c01649DOI Listing
April 2020

Identification of molecular mechanism underlying therapeutic effect of tanshinone IIA in the treatment of hypoxic vestibular vertigo via the NO/cGMP/BKCa signaling pathway.

Am J Transl Res 2019 15;11(7):4203-4213. Epub 2019 Jul 15.

Department of Otolaryngology, Baoshan Branch, Shuguang Hospital Affiliated with Shanghai University of Traditional Chinese Medicine Shanghai 201900, People's Republic of China.

This study aimed to investigate the molecular mechanisms underlying the effect of Tashinone IIA (Tan) on the treatment of ischemic vertigo. Sprague-Dawley (SD) male rats were divided into a SHAM group, a MODEL group, a MODEL+PBS group, a MODEL+Tan (10 mg/kg) group, a MODEL+Tan (20 mg/kg) group, a MODEL+Tan (40 mg/kg) group and a MODEL+Tan (80 mg/kg) group. The escape latency was observed among different groups of rats, while the production of NO/cGMP and the expression of BKCa were measured in vivo and in vitro by H&E staining, Western Blot and IHC assays. While the rats with ischemic vertigo showed prolonged escape latency, the treatment by Tan (40 mg/kg and up) shortened the escape latency in rats with ischemic vertigo. Moreover, the reduced production of NO/cGMP and expression of BKCa protein in the MODEL group were increased by a certain extent upon the treatment of 40 mg/kg or 80 mg/kg Tan. H&E staining of MVN neuron cells collected from different rat groups also validated the positive effects of Tan on the repair of damaged MVN neuron cells. Moreover, the above results were also validated in vitro, as the cells treated with 5 ug/ml and 10 ug/ml Tan increased the levels of NO/cGMP production and BKCa protein expression. At a certain dose, Tan could increase the production of NO and cGMP as well as the expression of BKCa, which would subsequently aid the treatment of ischemic vertigo.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6684908PMC
July 2019

Publisher Correction: Unusual 4H-phase twinned noble metal nanokites.

Nat Commun 2019 Jul 12;10(1):3147. Epub 2019 Jul 12.

Center for Programmable Materials, School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41467-019-11273-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6626029PMC
July 2019

Unusual 4H-phase twinned noble metal nanokites.

Nat Commun 2019 Jun 28;10(1):2881. Epub 2019 Jun 28.

Center for Programmable Materials, School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore.

Twinning commonly exists in noble metals. In recent years, it has attracted increasing interest as it is powerful to tune the physicochemical properties of metallic nanomaterials. To the best of our knowledge, all the reported twinned noble metal structures exclusively possess the close-packed {111} twinning plane. Here, we report the discovery of non-close-packed twinning planes in our synthesized Au nanokites. By using the bent Au nanoribbons with unique 4H/face-centered cubic)/4H crystal-phase heterostructures as templates, Au nanokites with unusual twinned 4H-phase structures have been synthesized, which possess the non-close-packed {10[Formula: see text]2} or {10[Formula: see text]6} twinning plane. By using the Au nanokites as templates, twinned 4H-phase Au@Ag and Au@PdAg core-shell nanostructures have been synthesized. The discovery of 4H-phase twinned noble metal nanostructures may pave a way for the preparation of metal nanomaterials with unique twinned structures for various promising applications.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41467-019-10764-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6598997PMC
June 2019

Comparative genomics of 40 edible and medicinal mushrooms provide an insight into the evolution of lignocellulose decomposition mechanisms.

3 Biotech 2019 Apr 28;9(4):157. Epub 2019 Mar 28.

1Institute of Microbiology, Beijing Forestry University, Beijing, 100083 People's Republic of China.

Diversity comparison and phylogenetic analyses of carbohydrate-active enzymes (CAZymes), auxiliary activities (AAs) and cytochromes P450 among 40 fungi, which are based on different nutritional pathways, help clarify and explain their divergence and improvement of various life-styles. Molecular clock analyses allow us to understand the evolutionary and developmental rules in decomposition gene families. Our results suggested that fungi in different ecological types acquired an obvious preference on specific decomposing gene families during evolutionary selection. White rot and litter saprotrophic fungi possessed more complete types of varied degradation gene families and were superior in quantities. With evolution and development of lignocellulose decomposition mechanism, certain families (like CBM1, GH6, GH7, GH10, and CYP53) disappeared in brown rot fungi and symbiotic fungi. In addition, the earlier time of phylogenetic divergence determined the more integrated and larger decomposition families. And various gains and losses in gene quantity of varied decomposition families led in particularly phylogenetic clades or nodes, then accelerated in forming varied ecotypes of species.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s13205-019-1689-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6439079PMC
April 2019

Two-dimensional tessellation by molecular tiles constructed from halogen-halogen and halogen-metal networks.

Nat Commun 2018 11 19;9(1):4871. Epub 2018 Nov 19.

Department of Chemistry, National University of Singapore, Singapore, 117543, Singapore.

Molecular tessellations are often discovered serendipitously, and the mechanisms by which specific molecules can be tiled seamlessly to form periodic tessellation remain unclear. Fabrication of molecular tessellation with higher symmetry compared with traditional Bravais lattices promises potential applications as photonic crystals. Here, we demonstrate that highly complex tessellation can be constructed on Au(111) from a single molecular building block, hexakis(4-iodophenyl)benzene (HPBI). HPBI gives rise to two self-assembly phases on Au(111) that possess the same geometric symmetry but different packing densities, on account of the presence of halogen-bonded and halogen-metal coordinated networks. Sub-domains of these phases with self-similarity serve as tiles in the periodic tessellations to express polygons consisting of parallelograms and two types of triangles. Our work highlights the important principle of constructing multiple phases with self-similarity from a single building block, which may constitute a new route to construct complex tessellations.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41467-018-07323-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6242836PMC
November 2018

DcC4H and DcPER Are Important in Dynamic Changes of Lignin Content in Carrot Roots under Elevated Carbon Dioxide Stress.

J Agric Food Chem 2018 Aug 19;66(30):8209-8220. Epub 2018 Jul 19.

State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Horticulture , Nanjing Agricultural University , Nanjing 210095 , People's Republic of China.

In our study, isobaric tags for relative and absolute quantification (iTRAQ) was conducted to determine the significantly changed proteins in the fleshy roots of carrots under different carbon dioxide (CO) treatments. A total of 1523 proteins were identified, of which 257 were differentially expressed proteins (DEPs). On the basis of annotation analysis, the DEPs were identified to be involved in energy metabolism, carbohydrate metabolism, and some other metabolic processes. DcC4H and DcPER, two lignin-related proteins, were identified from the DEPs. Under elevated CO stress, both carrot lignin content and the expression profiles of lignin biosynthesis genes changed significantly. The protein-protein interactions among lignin-related enzymes proved the importance of DcC4H and DcPER. The results of our study provided potential new insights into the molecular mechanism of lignin content changes in carrot roots under elevated CO stress.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.jafc.8b02068DOI Listing
August 2018

High phase-purity 1T'-MoS- and 1T'-MoSe-layered crystals.

Nat Chem 2018 06 2;10(6):638-643. Epub 2018 Apr 2.

Center for Programmable Materials, School of Materials Science and Engineering, Nanyang Technological University, Singapore, Singapore.

Phase control plays an important role in the precise synthesis of inorganic materials, as the phase structure has a profound influence on properties such as conductivity and chemical stability. Phase-controlled preparation has been challenging for the metallic-phase group-VI transition metal dichalcogenides (the transition metals are Mo and W, and the chalcogens are S, Se and Te), which show better performance in electrocatalysis than their semiconducting counterparts. Here, we report the large-scale preparation of micrometre-sized metallic-phase 1T'-MoX (X = S, Se)-layered bulk crystals in high purity. We reveal that 1T'-MoS crystals feature a distorted octahedral coordination structure and are convertible to 2H-MoS following thermal annealing or laser irradiation. Electrochemical measurements show that the basal plane of 1T'-MoS is much more active than that of 2H-MoS for the electrocatalytic hydrogen evolution reaction in an acidic medium.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41557-018-0035-6DOI Listing
June 2018

Crystal phase-based epitaxial growth of hybrid noble metal nanostructures on 4H/fcc Au nanowires.

Nat Chem 2018 04 12;10(4):456-461. Epub 2018 Mar 12.

Center for Programmable Materials, School of Materials Science and Engineering, Nanyang Technological University, Singapore, Singapore.

Crystal-phase engineering offers opportunities for the rational design and synthesis of noble metal nanomaterials with unusual crystal phases that normally do not exist in bulk materials. However, it remains a challenge to use these materials as seeds to construct heterometallic nanostructures with desired crystal phases and morphologies for promising applications such as catalysis. Here, we report a strategy for the synthesis of binary and ternary hybrid noble metal nanostructures. Our synthesized crystal-phase heterostructured 4H/fcc Au nanowires enable the epitaxial growth of Ru nanorods on the 4H phase and fcc-twin boundary in Au nanowires, resulting in hybrid Au-Ru nanowires. Moreover, the method can be extended to the epitaxial growth of Rh, Ru-Rh and Ru-Pt nanorods on the 4H/fcc Au nanowires to form unique hybrid nanowires. Importantly, the Au-Ru hybrid nanowires with tunable compositions exhibit excellent electrocatalytic performance towards the hydrogen evolution reaction in alkaline media.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41557-018-0012-0DOI Listing
April 2018

Preparation of High-Percentage 1T-Phase Transition Metal Dichalcogenide Nanodots for Electrochemical Hydrogen Evolution.

Adv Mater 2018 Mar 15;30(9). Epub 2018 Jan 15.

Center for Programmable Materials, School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore.

Nanostructured transition metal dichalcogenides (TMDs) are proven to be efficient and robust earth-abundant electrocatalysts to potentially replace precious platinum-based catalysts for the hydrogen evolution reaction (HER). However, the catalytic efficiency of reported TMD catalysts is still limited by their low-density active sites, low conductivity, and/or uncleaned surface. Herein, a general and facile method is reported for high-yield, large-scale production of water-dispersed, ultrasmall-sized, high-percentage 1T-phase, single-layer TMD nanodots with high-density active edge sites and clean surface, including MoS , WS , MoSe , Mo W S , and MoSSe, which exhibit much enhanced electrochemical HER performances as compared to their corresponding nanosheets. Impressively, the obtained MoSSe nanodots achieve a low overpotential of -140 mV at current density of 10 mA cm , a Tafel slope of 40 mV dec , and excellent long-term durability. The experimental and theoretical results suggest that the excellent catalytic activity of MoSSe nanodots is attributed to the high-density active edge sites, high-percentage metallic 1T phase, alloying effect and basal-plane Se-vacancy. This work provides a universal and effective way toward the synthesis of TMD nanostructures with abundant active sites for electrocatalysis, which can also be used for other applications such as batteries, sensors, and bioimaging.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/adma.201705509DOI Listing
March 2018

Edge Epitaxy of Two-Dimensional MoSe and MoS Nanosheets on One-Dimensional Nanowires.

J Am Chem Soc 2017 06 16;139(25):8653-8660. Epub 2017 Jun 16.

Center for Programmable Materials, School of Materials Science and Engineering, Nanyang Technological University , 50 Nanyang Avenue, Singapore 639798.

Rational design and synthesis of heterostructures based on transition metal dichalcogenides (TMDs) have attracted increasing interests because of their promising applications in electronics, catalysis, etc. However, the construction of epitaxial heterostructures with an interface at the edges of TMD nanosheets (NSs) still remains a great challenge. Here, we report a strategy for controlled synthesis of a new type of heterostructure in which TMD NSs, including MoS and MoSe, vertically grow along the longitudinal direction of one-dimensional (1D) CuS nanowires (NWs) in an epitaxial manner. The obtained CuS-TMD heterostructures with tunable loading amount and lateral size of TMD NSs are achieved by the consecutive growth of TMD NSs on CuS NWs through gradual injection of chalcogen precursors. After cation exchange of Cu in CuS-TMD heterostructures with Cd, the obtained CdS-MoS heterostructures retained their original architectures. Compared to the pure CdS NWs, the CdS-MoS heterostructures with 7.7 wt % loading of MoS NSs exhibit the best performance in the photocatalytic hydrogen evolution reaction with a H production rate up to 4647 μmol·h·g, about 58 times that catalyzed with pure CdS NWs. Our synthetic strategy opens up a new way for the controlled synthesis of TMD-based heterostructures, which could have various promising applications.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/jacs.7b03752DOI Listing
June 2017

Preparation of Ultrathin Two-Dimensional Ti Ta S O Nanosheets as Highly Efficient Photothermal Agents.

Angew Chem Int Ed Engl 2017 06 5;56(27):7842-7846. Epub 2017 Jun 5.

Center for Programmable Materials, School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore.

Although two-dimensional (2D) metal oxide/sulfide hybrid nanostructures have been synthesized, the facile preparation of ultrathin 2D nanosheets in high yield still remains a challenge. Herein, we report the first high-yield preparation of solution-processed ultrathin 2D metal oxide/sulfide hybrid nanosheets, that is, Ti Ta S O (x=0.71, 0.49, and 0.30), from Ti Ta S precursors. The nanosheet exhibits strong absorbance in the near-infrared region, giving a large extinction coefficient of 54.1 L g  cm at 808 nm, and a high photothermal conversion efficiency of 39.2 %. After modification with lipoic acid-conjugated polyethylene glycol, the nanosheet is a suitable photothermal agent for treatment of cancer cells under 808 nm laser irradiation. This work provides a facile and general method for the preparation of 2D metal oxide/sulfide hybrid nanosheets.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/anie.201703597DOI Listing
June 2017

A novel laccase from white rot fungus Trametes orientalis: Purification, characterization, and application.

Int J Biol Macromol 2017 Sep 26;102:758-770. Epub 2017 Apr 26.

Institute of Microbiology, Beijing Forestry University, Beijing 100083, China. Electronic address:

A novel laccase (Tolacc-T) from white rot fungus Trametes orientalis was enriched to apparent homogeneity with a specific activity of 20.667U/mg protein and recovery yield of 47.33%. The SDS-PAGE gave a single band indicating that Tolacc-T appears as a monomeric protein with a molecular mass of 44.0kDa. Domain structure analysis revealed that Tolacc-T contained a typical copper II binding domain and shared three potential N-glycosylation sites, but had no copper I binding domain, demonstrating that the enzyme is really a laccase, but a novel laccase. Optimal pH and temperature of Tolacc-T was 4.0 and 80°C, respectively, and it retained more than 80% of its original activity after 2h incubation at 10°C to 50°C. The enzyme exhibited strict substrate specificity towards ABTS but showed no or trace activities towards other substrates. Among the metals tested, Mn was proved to be the best activator for enhancing the laccase activity. A strongly inhibiting effect was found when NaN, -cysteine, and DTT were added to the enzyme. However, Tolacc-T activity was little bit inhibited in the presence of chelator EDTA. Furthermore, the enzyme was capable of degrading structurally different synthetic dyes in the absence of a redox mediator.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ijbiomac.2017.04.089DOI Listing
September 2017

Recent Advances in Ultrathin Two-Dimensional Nanomaterials.

Chem Rev 2017 May 17;117(9):6225-6331. Epub 2017 Mar 17.

Center for Programmable Materials, School of Materials Science and Engineering, Nanyang Technological University , 50 Nanyang Avenue, Singapore 639798, Singapore.

Since the discovery of mechanically exfoliated graphene in 2004, research on ultrathin two-dimensional (2D) nanomaterials has grown exponentially in the fields of condensed matter physics, material science, chemistry, and nanotechnology. Highlighting their compelling physical, chemical, electronic, and optical properties, as well as their various potential applications, in this Review, we summarize the state-of-art progress on the ultrathin 2D nanomaterials with a particular emphasis on their recent advances. First, we introduce the unique advances on ultrathin 2D nanomaterials, followed by the description of their composition and crystal structures. The assortments of their synthetic methods are then summarized, including insights on their advantages and limitations, alongside some recommendations on suitable characterization techniques. We also discuss in detail the utilization of these ultrathin 2D nanomaterials for wide ranges of potential applications among the electronics/optoelectronics, electrocatalysis, batteries, supercapacitors, solar cells, photocatalysis, and sensing platforms. Finally, the challenges and outlooks in this promising field are featured on the basis of its current development.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.chemrev.6b00558DOI Listing
May 2017

Elevated Carbon Dioxide Altered Morphological and Anatomical Characteristics, Ascorbic Acid Accumulation, and Related Gene Expression during Taproot Development in Carrots.

Front Plant Sci 2016 5;7:2026. Epub 2017 Jan 5.

State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Horticulture, Nanjing Agricultural University Nanjing, China.

The CO concentration in the atmosphere has increased significantly in recent decades and is projected to rise in the future. The effects of elevated CO concentrations on morphological and anatomical characteristics, and nutrient accumulation have been determined in several plant species. Carrot is an important vegetable and the effects of elevated CO on carrots remain unclear. To investigate the effects of elevated CO on the growth of carrots, two carrot cultivars ('Kurodagosun' and 'Deep purple') were treated with ambient CO (a[CO], 400 μmol⋅mol) and elevated CO (e[CO], 3000 μmol⋅mol) concentrations. Under e[CO] conditions, taproot and shoot fresh weights and the root/shoot ratio of carrot significantly decreased as compared with the control group. Elevated CO resulted in obvious changes in anatomy and ascorbic acid accumulation in carrot roots. Moreover, the transcript profiles of 12 genes related to AsA biosynthesis and recycling were altered in response to e[CO]. The 'Kurodagosun' and 'Deep purple' carrots differed in sensitivity to e[CO]. The inhibited carrot taproot and shoot growth treated with e[CO] could partly lead to changes in xylem development. This study provided novel insights into the effects of e[CO] on the growth and development of carrots.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fpls.2016.02026DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5221676PMC
January 2017

Laccase Production Among Medicinal Mushrooms from the Genus Flammulina (Agaricomycetes) Under Different Treatments in Submerged Fermentation.

Int J Med Mushrooms 2016 ;18(11):1049-1059

Institute of Microbiology, Beijing Forestry University, Beijing, China; State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.

The laccase activities of 13 strains of medicinal and edible mushrooms from the Flammulina genus (F. velutipes, F. rossica, and F. fennae) were studied. The effects of both fungal isolates and culture media were investigated. The laccase activities indicated significant differences among Flammulina strains (P < 0.001), and the cultural media significantly affected the laccase activities in Flammulina spp. (P < 0.001). The morphological characteristics of the 3 Flammulina species were similar, but differences in phylogenetic analysis and laccase activity existed among different species. Although isolates of each Flammulina species differed, the laccase variables among different Flammulina species were greater than those within the same species. The presence of simple carbon and nitrogen sources increased the maximum laccase enzyme activity, but the occurrence of both laccase activity and maximum laccase enzyme activity was delayed compared with lignocellulosic material. The laccase activities of most Flammulina isolates were increased when exposed to copper ions. Our findings offer insights into laccase productivity in response to different Flammulina species or strains and different submerged fermentation treatments.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1615/IntJMedMushrooms.v18.i11.90DOI Listing
March 2017

Anodized Aluminum Oxide Templated Synthesis of Metal-Organic Frameworks Used as Membrane Reactors.

Angew Chem Int Ed Engl 2017 01 5;56(2):578-581. Epub 2016 Dec 5.

Center for Programmable Materials, School of Materials Science and Engineering, 50 Nanyang Avenue, Singapore, 639798, Singapore.

The incorporation of metal-organic frameworks (MOFs) into membrane-shaped architectures is of great importance for practical applications. The currently synthesized MOF-based membranes show many disadvantages, such as poor compatibility, low dispersity, and instability, which severely limit their utility. Herein, we present a general, facile, and robust approach for the synthesis of MOF-based composite membranes through the in situ growth of MOF plates in the channels of anodized aluminum oxide (AAO) membranes. After being used as catalysis reactors, they exhibit high catalytic performance and stability in the Knoevenagel condensation reaction. The high catalytic performance might be attributed to the intrinsic structure of MOF-based composite membranes, which can remove the products from the reaction zone quickly, and prevent the aggregation and loss of catalysts during reaction and recycling process.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/anie.201610291DOI Listing
January 2017

In Situ Synthesis of Metal Sulfide Nanoparticles Based on 2D Metal-Organic Framework Nanosheets.

Small 2016 Sep 14;12(34):4669-74. Epub 2016 Jul 14.

Center for Programmable Materials, School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore.

A facile in situ synthetic method is developed to synthesize metal sulfide nanoparticles based on 2D M-TCPP (M = Cu, Cd, or Co, TCPP = tetrakis(4-carboxyphenyl)porphyrin)) metal-organic framework nanosheets. The obtained CuS/Cu-TCPP composite nanosheet is used as the active material in photoelectrochemical cells, showing notably increased photocurrent due to the improved exciton separation and charge carrier transport.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/smll.201600976DOI Listing
September 2016

Controlled growth of high-density CdS and CdSe nanorod arrays on selective facets of two-dimensional semiconductor nanoplates.

Nat Chem 2016 05 14;8(5):470-5. Epub 2016 Mar 14.

Center for Programmable Materials, School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore.

The rational synthesis of hierarchical three-dimensional nanostructures with specific compositions, morphologies and functionalities is important for applications in a variety of fields ranging from energy conversion and electronics to biotechnology. Here, we report a seeded growth approach for the controlled epitaxial growth of three types of hierarchical one-dimensional (1D)/two-dimensional (2D) nanostructures, where nanorod arrays of II-VI semiconductor CdS or CdSe are grown on the selective facets of hexagonal-shaped nanoplates, either on the two basal facets of the nanoplate, or on one basal facet, or on the two basal facets and six side facets. The seed engineering of 2D hexagonal-shaped nanoplates is the key factor for growth of the three resulting types of 1D/2D nanostructures. The wurtzite- and zinc-blende-type polymorphs of semiconductors are used to determine the facet-selective epitaxial growth of 1D nanorod arrays, resulting in the formation of different hierarchical three-dimensional (3D) nanostructures.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/nchem.2473DOI Listing
May 2016

Synthesis of 4H/fcc-Au@Metal Sulfide Core-Shell Nanoribbons.

J Am Chem Soc 2015 Sep 21;137(34):10910-3. Epub 2015 Aug 21.

School of Materials Science and Engineering, Nanyang Technological University , 50 Nanyang Avenue, Singapore 639798, Singapore.

Although great advances on the synthesis of Au-semiconductor heteronanostructures have been achieved, the crystal structure of Au components is limited to the common face-centered cubic (fcc) phase. Herein, we report the synthesis of 4H/fcc-Au@Ag2S core-shell nanoribbon (NRB) heterostructures from the 4H/fcc Au@Ag NRBs via the sulfurization of Ag. Remarkably, the obtained 4H/fcc-Au@Ag2S NRBs can be further converted to a novel class of 4H/fcc-Au@metal sulfide core-shell NRB heterostructures, referred to as 4H/fcc-Au@MS (M = Cd, Pb or Zn), through the cation exchange. We believe that these novel 4H/fcc-Au@metal sulfide NRB heteronanostructures may show some promising applications in catalysis, surface enhanced Raman scattering, solar cells, photothermal therapy, etc.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/jacs.5b06405DOI Listing
September 2015

Vaccination with different doses of Dermatophagoides farinae in a mouse model of allergic asthma.

Am J Med Sci 2015 Aug;350(2):116-20

Department of Respiratory (JH, YH, XJW), Children's Hospital, Chongqing Medical University, Chongqing, China; and Department of Neonate (M-KW), The First People's Hospital of Yibin, Yibin, China.

Background: The efficacy of vaccination with different doses of a vaccine has not been clarified. The purpose of this study was to investigate the relationship between the doses of purified house dust mite allergen, and allergic airway inflammation and airway reactivity in a mouse model of allergic asthma.

Methods: C57BL/6 mice were sensitized with Dermatophagoides farinae (Der f) and randomly treated with saline, 0.1, 1, or 2 mg Der f vaccine, respectively. The airway hyperresponsiveness, the numbers of total cells and eosinophils and the levels of interferon-γ and interleukin (IL)-4 in the bronchoalveolar lavage fluid (BALF) from individual mice were measured. The percentages of CD11c CD86 and CD11c MHC II+ dendritic cells were characterized, and the levels of IL-12 in the supernatants of cultured dendritic cells were measured.

Results: The airway hyperresponsiveness, the numbers of total cells and eosinophils in the BALF and the percentages of CD11c CD86 and CD11c MHC II+ dendritic cells were associated with immunologic downregulation. The levels of IFN-γ in the BALF and the levels of IL-12 in the supernatants of cultured dendritic cells were associated with immunologic upregulation. It was found that vaccination with the medium dose of Der f showed a stronger inhibitory effect.

Conclusions: There seems to be a dose-dependent response between allergen and both airway inflammation and hyperreactivity in the mouse model of allergic asthma.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1097/MAJ.0000000000000503DOI Listing
August 2015

Morphological Characteristics, Anatomical Structure, and Gene Expression: Novel Insights into Cytokinin Accumulation during Carrot Growth and Development.

PLoS One 2015 28;10(7):e0134166. Epub 2015 Jul 28.

State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Horticulture, Nanjing Agricultural University, Nanjing, 210095, China.

Cytokinins have been implicated in normal plant growth and development. These bioactive molecules are essential for cell production and expansion in higher plants. Carrot is an Apiaceae vegetable with great value and undergoes significant size changes over the process of plant growth. However, cytokinin accumulation and its potential roles in carrot growth have not been elucidated. To address this problem, carrot plants at five stages were collected, and morphological and anatomical characteristics and expression profiles of cytokinin-related genes were determined. During carrot growth and development, cytokinin levels were the highest at the second stage in the roots, whereas relatively stable levels were observed in the petioles and leaves. DcCYP735A2 showed high expression at stage 2 in the roots, which may contribute largely to the higher cytokinin level at this stage. However, expression of most metabolic genes did not follow a pattern similar to that of cytokinin accumulation, indicating that cytokinin biosynthesis was regulated through a complex network. Genes involved in cytokinin signal perception and transduction were also integrated to normal plant growth and development. The results from the present work suggested that cytokinins may regulate plant growth in a stage-dependent manner. Our work would shed novel insights into cytokinin accumulation and its potential roles during carrot growth. Further studies regarding carrot cytokinins may be achieved by modification of the genes involved in cytokinin biosynthesis, inactivation, and perception.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0134166PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4517795PMC
May 2016

AuAg nanosheets assembled from ultrathin AuAg nanowires.

J Am Chem Soc 2015 Feb 26;137(4):1444-7. Epub 2015 Jan 26.

School of Materials Science and Engineering, Nanyang Technological University , 50 Nanyang Avenue, Singapore 639798, Singapore.

Assembly of noble metal nanocrystals into free-standing two-dimensional (2D) nanostructures with a regular shape is still a challenge. Here we report the preparation of a novel 2D AuAg nanosheet with length of 1.50 ± 0.30 μm, width of 510 ± 160 nm, and thickness of ∼100 nm via the assembly of ultrathin AuAg nanowires in the presence of the triblock copolymer Pluronic P123. The self-assembly of P123 and the fusion behavior of the nanowires during the assembly process are the key reasons for the formation of AuAg nanosheets in P123. Furthermore, the obtained AuAg nanosheet@P123 is used as the active material in a memory device that exhibits the write-once-read-many-times memory behavior.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/ja513120uDOI Listing
February 2015

Liquid-phase epitaxial growth of two-dimensional semiconductor hetero-nanostructures.

Angew Chem Int Ed Engl 2015 Feb 21;54(6):1841-5. Epub 2014 Dec 21.

School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore) http://www.ntu.edu.sg/home/hzhang/

Although many two-dimensional (2D) hybrid nanostructures are being prepared, the engineering of epitaxial 2D semiconductor hetero-nanostructures in the liquid phase still remains a challenge. The preparation of 2D semiconductor hetero-nanostructures by epitaxial growth of metal sulfide nanocrystals, including CuS, ZnS and Ni3S2, is achieved on ultrathin TiS2 nanosheets by a simple electrochemical approach by using the TiS2 crystal and metal foils. Ultrathin CuS nanoplates that are 50-120 nm in size and have a triangular/hexagonal shape are epitaxially grown on TiS2 nanosheets with perfect epitaxial alignment. ZnS and Ni3S2 nanoplates can be also epitaxially grown on TiS2 nanosheets. As a proof-of-concept application, the obtained 2D CuS-TiS2 composite is used as the anode in a lithium ion battery, which exhibits a high capacity and excellent cycling stability.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/anie.201410890DOI Listing
February 2015

One-pot synthesis of CdS nanocrystals hybridized with single-layer transition-metal dichalcogenide nanosheets for efficient photocatalytic hydrogen evolution.

Angew Chem Int Ed Engl 2015 Jan 3;54(4):1210-4. Epub 2014 Dec 3.

School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore) http://www.ntu.edu.sg/home/hzhang/

Exploration of low-cost and earth-abundant photocatalysts for highly efficient solar photocatalytic water splitting is of great importance. Although transition-metal dichalcogenides (TMDs) showed outstanding performance as co-catalysts for the hydrogen evolution reaction (HER), designing TMD-hybridized photocatalysts with abundant active sites for the HER still remains challenge. Here, a facile one-pot wet-chemical method is developed to prepare MS2-CdS (M=W or Mo) nanohybrids. Surprisedly, in the obtained nanohybrids, single-layer MS2 nanosheets with lateral size of 4-10 nm selectively grow on the Cd-rich (0001) surface of wurtzite CdS nanocrystals. These MS2-CdS nanohybrids possess a large number of edge sites in the MS2 layers, which are active sites for the HER. The photocatalytic performances of WS2-CdS and MoS2-CdS nanohybrids towards the HER under visible light irradiation (>420 nm) are about 16 and 12 times that of pure CdS, respectively. Importantly, the MS2-CdS nanohybrids showed enhanced stability after a long-time test (16 h), and 70% of catalytic activity still remained.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/anie.201410172DOI Listing
January 2015