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1.
J Am Chem Soc ; 2020 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-32207939

RESUMO

Here we propose a strategy of radical oxidation reaction for the high-efficiency production of graphene oxide (GO). GO plays important roles in the sustainable development of energy and the environment, taking advantages of oxygen-containing functional groups for good dispersibility and assembly. Compared with Hummers' method, electrochemical exfoliation of graphite is considered facile and green, although the oxidation is fairly low. To synthesize GO with better crystallinity and higher oxidation degree, we present a photosynergetic electrochemical method. By using oxalate anions as the intercalation ions and co-reactant, the interfacial concentration of hydroxyl radicals generated during electrochemical exfoliation was promoted, and the oxidation degree was comparable with that of GO prepared by Hummers' method. In addition, the crystallinity was improved with fewer layers and larger size. Moreover, the aniline coassembled GO membrane was selectively permeable to water molecules by the hydrogen-bond interaction, but it was impermeable to Na+, K+, and Mg2+, due to the electrostatic interactions. Thus, it has a prospective application to water desalination and purification. This work opens a novel approach to the direct functionalization of graphene during the electroexfoliation processes and to the subsequent assembly of the functionalized graphene.

2.
Cancer Cell ; 37(3): 403-419.e6, 2020 Mar 16.
Artigo em Inglês | MEDLINE | ID: mdl-32183952

RESUMO

Natural killer/T cell lymphoma (NKTCL) is an aggressive and heterogeneous entity of non-Hodgkin lymphoma, strongly associated with Epstein-Barr virus (EBV) infection. To identify molecular subtypes of NKTCL based on genomic structural alterations and EBV sequences, we performed multi-omics study on 128 biopsy samples of newly diagnosed NKTCL and defined three prominent subtypes, which differ significantly in cell of origin, EBV gene expression, transcriptional signatures, and responses to asparaginase-based regimens and targeted therapy. Our findings thus identify molecular networks of EBV-associated pathogenesis and suggest potential clinical strategies on NKTCL.

3.
J Am Chem Soc ; 2020 Mar 24.
Artigo em Inglês | MEDLINE | ID: mdl-32207969

RESUMO

Understanding the reaction mechanism for the catalytic process is essential to rational design and synthesis of the highly efficient catalyst. MoS2 has been reported to be an efficient catalyst towards the electrochemical hydrogen evolution reaction (HER), but it still lacks direct experimental evidence to reveal the mechanism for MoS2-catalyzed electrochemical HER process at atomic level. In this work, we develop a wet-chemical synthetic method to prepare the single-layer MoS2-coated polyhedral Ag core-shell heter-ostructure (Ag@MoS2) with tunable sizes as efficient catalysts for the electrochemical HER. The Ag@MoS2 core-shell hetero-structures are used as ideal platforms for the real-time surface-enhanced Raman spectroscopy (SERS) study owing to the strong electromagnetic field which is generated in the plasmonic Ag core. The in situ SERS results provide solid Raman spectroscopic evidence proving the S-H bonding formation on the MoS2 surface during the HER process, suggesting that the S atom of MoS2 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.

4.
Artigo em Inglês | MEDLINE | ID: mdl-32207867

RESUMO

Understanding the activation and transfer of hydrogen species at interfacial sites is essential for catalytic hydrogenation, yet still remains a significant challenge. Herein, the spillover of hydrogen species and its role in tuning the activity and selectivity in catalytic hydrogenation have been investigated in situ using surface-enhanced Raman spectroscopy (SERS) with 10 nm spatial resolution through the precise fabrication of Au/TiO 2 /Pt sandwich nanostructures. In situ SERS study reveals that hydrogen species can efficiently spillover at Pt-TiO 2 -Au interfaces, and the ultimate spillover distance on TiO 2 is ~50 nm. Combining kinetic isotope experiment and density functional theory calculation, we find that the hydrogen spillover proceeds via the water-assisted cleavage and formation of surface hydrogen-oxygen bond. More importantly, the selectivity in the hydrogenation of the nitro or isocyanide group is manipulated by controlling the hydrogen spillover. This work provides molecular insights to deepen the understanding of hydrogen activation and boosts the design of active and selective catalysts for hydrogenation.

5.
Acc Chem Res ; 2020 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-32031367

RESUMO

The rational design of highly efficient catalysts relies on understanding their structure-activity relationships and reaction mechanisms at a molecular level. Such an understanding can be obtained by in situ monitoring of dynamic reaction processes using surface-sensitive techniques. Surface-enhanced Raman spectroscopy (SERS) can provide rich structural information with ultrahigh surface sensitivity, even down to the single-molecule level, which makes it a promising tool for the in situ study of catalysis. However, only a few metals (like Au, Ag, and Cu) with particular nanostructures can generate strong SERS effects. Thus, it is almost impossible to employ SERS to study transition metals (like Pt, Pd, Ru, etc.) and other nonmetal materials that are usually used in catalysis (material limitation). Furthermore, SERS is also unable to study model single crystals with atomically flat surface structures or practical nanocatalysts (morphology limitation). These limitations have significantly hindered the applications of SERS in catalysis over the past four decades since its discovery, preventing SERS from becoming a widely used technique in catalysis. In this Account, we summarize the extensive efforts done by our group since the 1980s, particularly in the past decade, to overcome the material and morphology limitations in SERS. Particular attention has been paid to the work using core-shell nanostructures as SERS substrates, because they provide high Raman enhancement and are highly versatile for application on different catalytic materials. Different SERS methodologies for catalysis developed by our group, including the "borrowing" strategy, shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS), and SHINERS-satellite strategy, are discussed in this account, with an emphasis on their principles and applications. These methodologies have successfully overcome the long-standing limitations of traditional SERS, enabling in situ tracking of catalysis at model single-crystal surfaces and practical nanocatalysts that can hardly be studied by SERS. Using these methodologies, we systematically studied a series of fundamentally important reactions, such as oxygen reduction reaction, hydrogen evolution reaction, electrooxidation, CO oxidation, and selective hydrogenation. As such, direct spectroscopic evidence of key intermediates that can hardly be detected by other traditional techniques was obtained. Combined with density functional theory and other in situ techniques, the reaction mechanisms and structure-activity relationships of these catalytic reactions were revealed at a molecular level. Furthermore, the future of SERS in catalysis has also been proposed in this work, which we believe should be focused on the in situ dynamic studies at the single-molecule, or even single-atom, level using techniques with ultrahigh sensitivity or spatial resolution, for example, single-molecule SERS or tip-enhanced Raman spectroscopy. In summary, core-shell nanostructure-enhanced Raman spectroscopies are shown to greatly boost the application of SERS in catalysis, from model systems like single-crystal surfaces to practical nanocatalysts, liquid-solid interfaces to gas-solid interfaces, and electrocatalysis to heterogeneous catalysis to photocatalysis. Thus, we believe this Account would attract increasing attention to SERS in catalysis and opens new avenues for catalytic studies.

6.
Nanoscale ; 2020 Feb 24.
Artigo em Inglês | MEDLINE | ID: mdl-32091518

RESUMO

In situ monitoring of electrocatalytic processes at solid-liquid interfaces is essential for the fundamental understanding of reaction mechanisms, yet quite challenging. Herein, Pt-on-Au nanocatalysts with a Au-core Pt-satellite superstructure have been fabricated. In such Pt-on-Au nanocatalysts, the Au cores can greatly amplify the Raman signals of the species adsorbed on Pt, allowing the in situ surface-enhanced Raman spectroscopy (SERS) study of the electrocatalytic reactions on Pt. Using the combination of an electrochemical method and in situ SERS, size effects of Pt on the catalytic performance of the core-satellite nanocomposites towards CO and methanol electrooxidation are revealed. It is found that such Pt-on-Au nanocomposites show improved activity and long-term stability for the electrooxidation of CO and methanol with a decrease in the Pt size. This work demonstrates an effective strategy to achieve the in situ monitoring of electrocatalytic processes and to simultaneously boost their catalytic performance towards electrooxidation.

7.
Biosens Bioelectron ; 154: 112067, 2020 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-32056962

RESUMO

The creatinine concentration of human urine is closely related to human kidney health and its rapid, quantitative, and low-cost detection has always been demanded. Herein, a surface-enhanced Raman spectroscopic (SERS) method for rapid and cost-effective quantification of creatinine concentrations in human urine was developed. A Au nanoparticle solution (Au sol) was used as a SERS substrate and the influence of different agglomerating salts on its sensitivity toward detecting creatinine concentrations was studied and optimized, as well as the effect of both the salt and Au sol concentrations. The variation in creatinine spectra over time on different substrates was also examined, demonstrating reproducible quantitative analysis of creatinine concentrations in solution. By adjusting the pH, a simple liquid-liquid solvent extraction procedure, which extracted creatinine from human urine, was used to increase the SERS detection selectivity toward creatinine in complex matrices. The quantitative results were compared to those obtained with a clinically validated enzymatic "creatinine kit (CK)." The limit of detection (LOD) for the SERS technique was 1.45 mg L-1, compared with 3.4 mg L-1 for the CK method. Furthermore, cross-comparing the results from the two methods, the average difference was 5.84% and the whole SERS detection process could be completed within 2 min compared with 11 min for the CK, indicating the practicality of the quantitative SERS technique. This novel quantitative technique shows promises as a high-throughput platform for relevant clinical and forensic analysis.

8.
Chem Commun (Camb) ; 56(7): 1129-1132, 2020 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-31894774

RESUMO

Shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) is applied to the study of a state-of-the-art water oxidation electrocatalyst, IrOx, during oxygen evolution. The excellent sensitivity allows for in situ detection of surface intermediate species during cyclic voltammetry. Features in the Raman spectrum are correlated with the redox behaviour of the electrode, demonstrating a way to study the mechanisms of electrocatalytic water splitting using equipment available in most laboratories.

9.
J Chem Phys ; 152(1): 014702, 2020 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-31914769

RESUMO

Light-matter interactions in nanostructures have shown great potential in physics, chemistry, surface science, materials science, and nanophotonics. Herein, for the first time, the feasibility of strong coupling between plasmon-induced magnetic resonant and propagating surface plasmonic modes at visible light frequencies is theoretically demonstrated. Taking advantage of the strong coupling between these modes allowed for a narrow-linewidth hybrid mode with a huge electromagnetic field enhancement to be acquired. This work can serve as a promising guide for designing a platform with strong coupling based on magnetic resonance at visible and even ultraviolet light frequencies and also offers an avenue for further exploration of strong light-matter interactions at the nanoscale.

10.
J Affect Disord ; 265: 590-594, 2020 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-31787422

RESUMO

BACKGROUND: Major depressive disorder (MDD) is common among older adults. The epidemiology of MDD is greatly influenced by sociocultural and economic factors. This study examined the 1-month and lifetime prevalence of MDD and its socio-demographic correlates in older adults living in Hebei province, an agricultural area of China. METHODS: Multistage, stratified, random sampling was administered between April and August 2016. The diagnosis of MDD was established with the Structured Clinical Interview for the Diagnostic and Statistical Manual of Mental Disorders fourth edition (DSM-IV) Axis I Disorders. RESULTS: A total of 3911 participants were enrolled. The 1-month and lifetime prevalence of MDD in older adults was 2.0% (95%CI: 1.6-2.4%) and 3.4% (95%CI: 2.8-4.0%), respectively. Multivariable logistic regression analyses revealed that female gender [P < 0.001, adjusted odds ratio (aOR) = 2.6, 95%CI: 1.53-4.53], presence of comorbid major medical conditions (P < 0.001, aOR = 4.8, 95%CI: 2.17-10.39) and family history of psychiatric disorders (P = 0.013, aOR = 3.4, 95%CI: 1.30-8.96) were independently and significantly associated with higher odds of MDD. CONCLUSION: The prevalence of MDD in older adults in Hebei province, China, was lower than most findings in China and other countries. Nevertheless, continued surveillance of elderly depression in China along with the development of primary, secondary and tertiary preventative interventions for the elderly with MDD is indicated.

11.
ACS Nano ; 14(1): 28-117, 2020 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-31478375

RESUMO

The discovery of the enhancement of Raman scattering by molecules adsorbed on nanostructured metal surfaces is a landmark in the history of spectroscopic and analytical techniques. Significant experimental and theoretical effort has been directed toward understanding the surface-enhanced Raman scattering (SERS) effect and demonstrating its potential in various types of ultrasensitive sensing applications in a wide variety of fields. In the 45 years since its discovery, SERS has blossomed into a rich area of research and technology, but additional efforts are still needed before it can be routinely used analytically and in commercial products. In this Review, prominent authors from around the world joined together to summarize the state of the art in understanding and using SERS and to predict what can be expected in the near future in terms of research, applications, and technological development. This Review is dedicated to SERS pioneer and our coauthor, the late Prof. Richard Van Duyne, whom we lost during the preparation of this article.

12.
J Affect Disord ; 263: 129-133, 2020 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-31818768

RESUMO

BACKGROUND: Few studies have estimated the prevalence and correlates of bipolar disorder (BP) in agricultural areas of China. This study examined the one-month and lifetime prevalence of BP, its subtypes and socio-demographic factors in the adult population of Hebei province, a predominantly agricultural area of China. METHODS: A multistage, stratified, cluster random sampling method was used to estimate the prevalence and correlates of BP in adults in Hebei province, China. The expanded version of the 12-item General Health Questionnaire (GHQ-12) and the Structured Clinical Interview for DSM-IV Axis I Disorders-Patient Edition (SCID-I/P/C) were administered to establish the diagnosis of BP. RESULTS: A total of 20,884 participants were screened. The weighted lifetime prevalence of BP, BP type I (BP-I), type II (BP-II), and BP not otherwise specified (BP-NOS) were 0.20% (95% CI: 0.14-0.26%), 0.13% (95% CI: 0.08-0.18%), 0.03% (95% CI: 0.009-0.06%) and 0.03% (95% CI: 0.009-0.06%), respectively. The weighted one-month prevalence estimates were 0.12% (95% CI: 0.08-0.17%) for BP, 0.07% (95% CI: 0.04-0.11%) for BP-I, 0.03% (95% CI: 0.006-0.05%) for BP-II, and 0.02% (95% CI: 0.003-0.04%) for BP-NOS. Multiple Poisson regression analysis revealed that positive family history of any psychiatric disorder (P<0.001, OR=6.48, 95% CI: 2.53-16.56) was significantly associated with greater risk of BP. CONCLUSION: The prevalence of BP in Hebei province appears lower than in most areas of China and other countries. Continued surveillance of BP in China along with the development of primary and tertiary preventative interventions for psychiatric disorders is indicated.

13.
J Nat Prod ; 83(1): 79-87, 2020 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-31886665

RESUMO

The effects of a single-amino-acid culture strategy on secondary metabolite production in the marine-derived fungus Trichoderma erinaceum F1-1 were investigated by culturing the fungus in GPY medium supplemented or not supplemented with l-phenylalanine. A suite of secondary metabolites, including seven terpenoids (1-7) and one polyketide (8), among which are four new compounds, harziandione A (1), cyclonerodiols A and B (3, 4), and trichodermaerin A (6), were isolated from the GPY medium without l-phenylanine, whereas 18 aromatic compounds (9-26), including six new compounds, trichoderolides A-F (9, 10, and 14-17), were isolated from the culture grown in the GPY medium with l-phenylalanine. The structures of the new compounds were determined by high-resolution mass spectrometry, NMR spectroscopic analysis, optical rotation calculations, chemical methods, and X-ray crystallography. Compounds 10, 12, 13, and 26 exhibited cytotoxic activities against MDA-MB-435 human melanocyte cancer cells. Compound 26 was cytotoxic to A549 adenocarcinomic human alveolar basal epithelial cells.

14.
J Am Chem Soc ; 142(2): 715-719, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31887023

RESUMO

The study of the oxygen reduction reaction (ORR) at high-index Pt(hkl) single crystal surfaces has received considerable interest due to their well-ordered, typical atomic structures and superior catalytic activities. However, it is difficult to obtain direct spectral evidence of ORR intermediates during reaction processes, especially at high-index Pt(hkl) surfaces. Herein, in situ Raman spectroscopy has been employed to investigate ORR processes at high-index Pt(hkl) surfaces containing the [011̅] crystal zone-i.e., Pt(211) and Pt(311). Through control and isotope substitution experiments, in situ spectroscopic evidence of OH and OOH intermediates at Pt(211) and Pt(311) surfaces was successfully obtained. After detailed analysis based on the Raman spectra and theoretical simulation, it was deduced that the difference in adsorption of OOH at high-index surfaces has a significant effect on the ORR activity. This research illuminates and deepens the understanding of the ORR mechanism on high-index Pt(hkl) surfaces and provides theoretical guidance for the rational design of high activity ORR catalysts.

15.
Cell Host Microbe ; 26(6): 810-822.e7, 2019 12 11.
Artigo em Inglês | MEDLINE | ID: mdl-31830443

RESUMO

Living organisms can be primed for potentiated responses to recurring stresses based on prior experience. However, the molecular basis of immune priming remains elusive in plants that lack adaptive immunity. Here, we report that bacterial challenges can prepare plants for fungal attacks by inducing juxtamembrane phosphorylation of CERK1, the co-receptor indispensable for signaling in response to the fungal elicitor chitin. This phosphorylation is mediated by BAK1, a co-receptor for signaling in response to multiple elicitors. BAK1 interacts with CERK1, and loss of BAK1 reduces priming phosphorylation of CERK1. Juxtamembrane phosphomimetic mutations of CERK1 confer accelerated chitin responses and fortified fungal resistance without triggering constitutive immunity, whereas juxtamembrane phosphodeficient mutations diminish bacteria-induced protection against fungal infection. These findings reveal that crosstalk between cell-surface immune co-receptors can prime defense and demonstrate that juxtamembrane phosphorylation of plant receptor-like kinases can occur independent of kinase activation to place the protein into a prime state.

16.
Anal Chem ; 2019 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-31682106

RESUMO

Surface enhanced Raman spectroscopy (SERS) is an ultrasensitive label-free analytical technique that can provide unique chemical and structural fingerprint information. However, gaining reliable quantitative analysis with SERS remains a huge challenge because of poor reproducibility and the instability of nanostructured SERS active surfaces. Herein, an effective strategy of coating Au nanoparticles (NPs) with ultrathin and uniform Prussian blue (PB) shell (Au@PB NPs) was developed for quantitative detection of dopamine (DA) concentrations in blood serum and crystal violet (CV) contaminants in lake water. The only intense PB Raman signal at 2155 cm-1 served as an ideal and interference-free internal standard (IS) for correcting fluctuations in the Raman intensities of analytes. Also, the stability of Au@PB NPs was investigated, exhibiting good functionality in strong acid solutions and thermal stability at 100 °C. This work demonstrates a convenient and fast quantitative SERS technique for detecting analyte concentrations in complex systems and has a great number of potential applications for use in analytical chemistry.

17.
Int J Mol Sci ; 20(22)2019 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-31717686

RESUMO

Plant genome sequences are presently deciphered at a staggering speed, due to the rapid advancement of high-throughput sequencing technologies. However, functional genomics significantly lag behind due to technical obstacles related to functional redundancy and mutant lethality. Artificial microRNA (amiRNA) technology is a specific, reversible, and multiplex gene silencing tool that has been frequently used in generating constitutive or conditional mutants for gene functional interrogation. The routine approach to construct amiRNA precursors involves multiple polymerase chain reactions (PCRs) that can increase both time and labor expenses, as well as the chance to introduce sequence errors. Here, we report a simplified method to clone and express amiRNAs in Arabidopsis and rice based on the engineered Arabidopsis miR319a or rice miR528 precursor, which harbor restriction sites to facilitate one-step cloning of a single PCR product. Stem-loop reverse-transcriptase quantitative PCR (RT-qPCR) and functional assays validated that amiRNAs can be accurately processed from these modified precursors and work efficiently in plant protoplasts. In addition, Arabidopsis transgenic plants overexpressing the modified miR319a precursor or its derived amiRNA could exhibit strong gene silencing phenotypes, as expected. The simplified amiRNA cloning strategy will be broadly useful for functional genomic studies in Arabidopsis and rice, and maybe other dicotyledon and monocotyledon species as well.

18.
J Integr Plant Biol ; 2019 Nov 22.
Artigo em Inglês | MEDLINE | ID: mdl-31755168

RESUMO

Deciphering protein-protein interactions (PPIs) is fundamental for understanding signal transduction pathways in plants. The split firefly luciferase (Fluc) complementation (SLC) assay has been widely used for analyzing PPIs. However, concern has risen about the bulky halves of Fluc interfering with the functions of their fusion partners. Nano luciferase (Nluc) is the smallest substitute for Fluc with improved stability and luminescence. Here, we developed a dual-use system enabling the detection of PPIs through the Nluc-based SLC and co-immunoprecipitation assays. This was realized by coexpression of two proteins under investigation in fusion with the HA- or FLAG-tagged Nluc halves, respectively. We validated the robustness of this system by reproducing multiple previously documented PPIs in protoplasts or Agrobacterium-transformed plants. We next applied this system to evaluate the homodimerization of Arabidopsis CERK1, a coreceptor of fungal elicitor chitin, and its heterodimerization with other homologs in the absence or presence of chitin. Moreover, split fragments of Nluc were fused to two cytosolic ends of Arabidopsis calcium channels CNGC2 and CNGC4 to help sense the allosteric change induced by the bacterial elicitor flg22. Collectively, these results demonstrate the usefulness of the Nluc-based SLC assay for probing constitutive or inducible PPIs and protein allostery in plant cells.

19.
Small ; 15(47): e1903674, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31588678

RESUMO

Direct photoexcitation of charges at a plasmonic metal hotspot produces energetic carriers that are capable of performing photocatalysis in the visible spectrum. However, the mechanisms of generation and transport of hot carriers are still not fully understood and under intense investigation because of their potential technological importance. Here, spectroscopic evidence proves that the reduction of dye molecules tethered to a Au(111) surface can be triggered by plasmonic carriers via a tunneling mechanism, which results in anomalous Raman intensity fluctuations. Tip-enhanced Raman spectroscopy (TERS) helps to correlate Raman intensity fluctuations with temperature and with properties of the molecular spacer. In combination with electrochemical surface-enhanced Raman spectroscopy, TERS results show that plasmon-induced energetic carriers can directly tunnel to the dye through the spacer. This organic spacer chemically isolates the adsorbate from the metal but does not block photo-induced redox reactions, which offers new possibilities for optimizing plasmon-induced photocatalytic systems.

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