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1.
Cell Biol Toxicol ; 2021 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-33400020

RESUMO

Cholestatic liver injury, a group of diseases characterized with dysregulated bile acid (BA) homeostasis, was partly resulted from BA circulation disorders, which is commonly associated with the damage of hepatocyte barrier function. However, the underlying hepatocyte barrier-protective molecular mechanisms of cholestatic liver injury remain poorly understood. Interestingly, recent studies have shown that sphingosine-1-phosphate (S1P) participated in the process of cholestasis by activating its G protein-coupled receptors S1PRs, regaining the integrity of hepatocyte tight junctions (TJs). Here, we showed that SEW2871, a selective agonist of sphingosine-1-phosphate receptor 1(S1PR1), alleviated ANIT-induced TJs damage in 3D-cultured mice primary hepatocytes. Molecular mechanism studies indicated that AMPK signaling pathways was involved in TJs protection of SEW2871 in ANIT-induced hepatobiliary barrier function deficiency. AMPK antagonist compound C (CC) and agonist AICAR were all used to further identify the important role of AMPK signaling pathway in SEW2871's TJs protection of ANIT-treated mice primary hepatocytes. The in vivo data showed that SEW2871 ameliorated ANIT-induced cholestatic hepatotoxicity. Further protection mechanism research demonstrated that SEW2871 not only regained hepatocyte TJs by the upregulated S1PR1 via AMPK signaling pathway, but also recovered hepatobiliary barrier function deficiency, which was verified by the restored BA homeostasis by using of high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS). These results revealed that the increased expression of S1PR1 induced by SEW2871 could ameliorate ANIT-induced cholestatic liver injury through improving liver barrier function via AMPK signaling and subsequently reversed the disrupted BA homeostasis. Our study provided strong evidence that S1PR1 may be a promising therapeutic approach for treating intrahepatic cholestatic liver injury. Graphical abstract.

2.
Artigo em Inglês | MEDLINE | ID: mdl-33400122

RESUMO

In the last few decades, the eutrophication of lakes has been a serious issue in the middle and lower reaches of the Yangtze River watershed. To explore the relationship between lake systems and anthropogenic activities, sediments were collected from the Shuanglong reservoir in the Dianchi watershed in Southwest China. Total nitrogen (TN), total phosphorus (TP), total organic carbon (TOC), and the carbon isotopic ratio (δ13C) were analyzed in sediment cores to reconstruct the effects of natural succession and human activities on the past lacustrine environmental conditions. A reliable chronology of the sediment core was established by using the 210Pb dating technique, which indicated that the age span of the 70-cm sediment core is from the years 1871 to 2011. Above - 31 cm depth in the core, TN, TP, TOC, C/N, and δ13C increased significantly, indicating that eutrophication has occurred since the 1980s. By combining the indicators of δ13C and C/N, it was shown that terrestrial and lacustrine components were the main sources of organic matter (OM) in the reservoir, which was mostly controlled by terrestrial C3 plants and algae. Since the 1980s, increased sewage discharge, fish aquaculture, fertilizer application, population, and economic strength have sped up the eutrophication process, and the eutrophication was further intensified in 2001.

3.
Chemosphere ; 265: 129133, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33276997

RESUMO

Microplastics are a kind of new organic pollutant in the environment. In this study, the adsorption of tetracyclines (TCs), including tetracycline hydrochloride (TC), chlortetracycline hydrochloride (CTC) and oxytetracycline hydrochloride (OTC) onto polyethylene (PE) microplastics in aqueous solutions were investigated. The mechanism of the adsorption behavior was preliminarily explored by adsorption kinetics, isotherms, and thermodynamics, in combination with scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). In addition, molecular dynamics (MD) simulation was applied to investigate the adsorption processes of TCs on PE at a molecular level. It was found that the adsorption behaviors of TCs reached an equilibrium state within 30 h. The experimental data showed that adsorption capacities of TCs onto PE were as follows: OTC (64.40 ± 2.38 µg/g)>CTC (63.36 ± 4.92 µg/g)>TC (53.52 ± 3.43 µg/g). TC sorption onto PE increased with pH, peaking at around pH 6 and then decreased. The increase of ionic strength in the solution led to the reduced adsorption capacity of TC onto PE. The results indicated that the experimental data were well fitted by the pseudo-second-order model and the Freundlich isotherm model, indicating both monolayer and multilayer coverage of TCs onto the surface of PE. The results of MD simulation showed that PE can effectively adsorb the TCs molecule mainly through non-bond interactions, and PE exhibited the highest affinity for CTC and OTC, followed by TC.


Assuntos
Microplásticos , Poluentes Químicos da Água , Adsorção , Concentração de Íons de Hidrogênio , Cinética , Simulação de Dinâmica Molecular , Plásticos , Polietileno , Espectroscopia de Infravermelho com Transformada de Fourier , Tetraciclinas , Poluentes Químicos da Água/análise
4.
J Foot Ankle Surg ; 60(1): 6-10, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-32253154

RESUMO

With the development of recent technology, radiographs can be saved digitally, and angular measurements can be processed using various software packages. We developed an innovative computer-aided design method with Materialize Interactive Medical Image Control System software to measure hallux valgus angle (HVA), the intermetatarsal angle (IMA), and the distal metatarsal articular angle (DMAA) and assessed its concordance with traditional X-ray imaging methods. All measurements were carried out on 42 feet from 26 adult patients diagnosed with hallux valgus who were prospectively selected from July 2016 to April 2018. Standing X-ray radiograph and weightbearing computed tomography scans were conducted on all patients, and HVA, IMA, and DMAA were generated using both a traditional X-ray method and our innovative method. Two different observers assessed measurements for each patient. Finally, statistical analyses were conducted to assess the reliability of the measurements. Both X-ray imaging and our innovative method had strong interobserver and test-retest reliability. The ICC of X-ray imaging was 0.945, p < .001, and the ICC of the innovative method was 0.915, p < .001. There was no statistical difference between the 2 methods for HVA and IMA measurements (p > .05); however, a difference was detected for DMAA (p < .05). Bland-Altman analyses demonstrated a high degree of agreement between the 2 methods for HVA and IMA, but a significant difference for DMAA. From the results, we concluded that our innovative computer-aided design method is a feasible, reliable way to quantitatively assess HVA, IMA, and DMAA, and it is likely more accurate for measuring DMAA.

5.
Int J Biol Macromol ; 166: 1072-1081, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-33157143

RESUMO

Luteolin, a plant-derived flavonoid, was found to exert effective inhibitory effect to peroxidase activity in a non-competitive manner with an IC50 of (6.62 ± 0.45) × 10-5 mol L-1. The interaction between luteolin and peroxidase induced the formation of a static complex with a binding constant (Ksv) of 7.31 × 103 L mol-1 s-1 driven by hydrogen bond and hydrophobic interaction. Further, the molecular interaction between luteolin and peroxidase resulted in intrinsic fluorescence quenching, structural and conformational alternations which were determined by multispectroscopic techniques combined with computational molecular docking. Molecular docking results revealed that luteolin bound to peroxidase and interacted with relevant amino acid residues in the hydrophobic pocket. These results will provide information for screening additional peroxidase inhibitors and provide evidence of luteolin's potential application in preservation and processing of fruit and vegetables and clinical disease remedy.

6.
Neurosci Lett ; 742: 135520, 2021 01 18.
Artigo em Inglês | MEDLINE | ID: mdl-33246026

RESUMO

Parkinson's disease (PD) is a common neurodegenerative disorder characterized by the loss of midbrain dopaminergic (DA) neurons. Neural stem cells (NSCs) are the most promising cells for cell-replacement therapy for PD. However, the poor differentiation and maturation of DA neurons and decreased cell survival after transplantation are a challenge. Tetrahydroxystilbene glucoside (2,3,5,4'-tetrahydroxystilbene-2-O-glucoside; TSG), an active component of the popular traditional Chinese medicinal plant Polygonum multiflorum Thunb, possesses multiple pharmacological actions. In this study, we determined whether TSG can induce neural stem cell (NSCs) differentiation into neurons, especially DA neurons, and the possible involvement of Wnt/ß-catenin signaling pathways. Results revealed that NSCs differentiated primarily into astrocytes when cultured in 2 % serum-containing medium. However, TSG treatment during NSC differentiation in vitro increased the number of Tuj-1-positive neurons, as well as the proportion of tyrosine hydroxylase(TH)-positive cells and dopamine- transporter- positive neurons, a late marker of mature DA neurons. We also found that TSG enhanced the expression of nuclear receptor related factor 1, a transcription factor specific for the development and maintenance of midbrain DA neurons in inducing NSC differentiation into TH -immunoreactive DA neurons. Moreover, TSG upregulated the expression of Wnt/ß-catenin signaling molecules (Wnt1, Wnt3a, Wnt5a, and ß-catenin). However, these promoting effects were significantly inhibited by the application of IWR1, a Wnt signaling-specific blocker in culture. Our findings suggested that TSG may have potential in inducing the DA neuronal differentiation of mouse NSCs mediated by triggering the Wnt/ß-catenin signaling pathway. These results indicated the possible role for TSG in the transplantation of NSCs for PD.

7.
J Equine Vet Sci ; 96: 103312, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33349402

RESUMO

The objective of the present study was to evaluate the probiotic properties, security and antibacterial ability in vivo of isolated strains from healthy equine. In the present study, two Pediococcus acidilactici (P1 and P2) and two Lactobacillus equi (L1 and L2) were isolated. All isolates were died when exposed to pH 2.0 for 3 hours but survived at pH 3.0 and pH 4.0 with differential survival rate, and there is a higher survival rate at pH 4.0. Similarly, the isolates showed different tolerance to bile. The viable bacteria count was sustained at high levels in a tolerance test with artificial gastrointestinal fluid. The isolates survived and grew at temperatures between 37 and 55°C but died at 65°C. Four strains exhibited inhibitory activity against pathogens, including Salmonella typhimurium (CVCC542), Escherichia coli (C83902), Staphylococcus aureus (BNCC186335), and Pasteurella multocida (clinical isolate). These isolates exhibited differential antibiotic susceptibility. In safety trials, all isolates were γ-hemolytic, and the oral toxicity of strains P1 (gavaged with 1 × 109 CFU/day) and L1 (gavaged with 1 × 109 CFU/day) were analyzed in mice. There were no effects on the overall health status of mice. There were no prominent differences in the incidence of bacteria translocation to blood, liver, and spleen. Mice gavaged with Pediococcus acidilactici P1 (1 × 108 CFU/day) or Lactobacillus equi L1 (1 × 108 CFU/day) as prevention showed lower rates of diarrhea and mortality after being challenged with Salmonella typhimurium (4 × 106 CFU signal dose, 0.1 mL by intragastric gavage). The results indicate that the isolated strains could act as potential probiotics, providing a new way to reduce salmonella infection, which merit future application studies.

8.
Thorac Cancer ; 12(1): 122-127, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33155374

RESUMO

Situs inversus totalis (SIT) is an extremely rare anomaly characterized by a left-to-right reversal of all the thoracic and abdominal organs. Only 11 cases of esophageal cancer with SIT have been reported worldwide, most of which underwent hybrid minimally invasive esophagectomy (MIE) but not total MIE. Here, we report a case of esophageal cancer with SIT successfully treated by total MIE, with a right lateral-prone position adopted during the thoracic procedure. The relevant literature is also discussed and reviewed.

9.
Bioorg Med Chem Lett ; 34: 127754, 2020 Dec 19.
Artigo em Inglês | MEDLINE | ID: mdl-33347967

RESUMO

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by synovitise, and its pathogenesis is complicated. Sphingosine-1-phosphate (S1P) is a lipid produced by sphingosine kinase 1 and 2 (SphK1/2), which participate in some of most-spread skeletal diseases such as rheumatoid arthritis or osteoarthritis. To explore the anti-inflammatory activity of 2-epi-jaspine B analogs as SphKs inhibitors, we used LPS-induced rheumatoid arthritis fibroblast-like synovial cells (HFLS-RA) as the research object to evaluate the anti-inflammatory activity of 16 2-epi-jaspine B analogs and the newly synthesized salt CHJ01. We found that 2-epi-jaspine B analog CHJ01 in hydrochloride salt form has excellent SphK1 inhibitory effect and better anti-RA effect. CHJ01 showed an anti-inflammatory effect similar to that of MTX in vitro, its IC50 value is 8.64 µM. Moreover, the anti-RA effect of CHJ01 was also studied by using a Complete Freund's Adjuvant (CFA)-induced arthritis (AIA) in a rat mode. Pharmacological experiments show that CHJ01 can help to significantly improve the symptoms of rheumatoid arthritis by reducing the swelling volume, arthritis score, spleen index and the level of IL-1ß, TNF-α, IL-6 of AIA rats. Therefore, CHJ01 holds high potential for the treatment of RA.

10.
ACS Nano ; 2020 Dec 30.
Artigo em Inglês | MEDLINE | ID: mdl-33377388

RESUMO

The design of efficient copper-based (Cu-based) carbon dioxide reduction (CO2RR) electrocatalysts is crucial for converting CO2 to value-added liquid products. In this work, we demonstrate that the strong synergy between Cu core and ultrathin lead (Pb) shell (0.7 nm) in the Cu/Pb core/shell nanocrystals (NCs, CuPb-0.7/C) significantly boosts the electrocatalytic reduction of CO2 toward C2+ products (products with at least two carbon atoms). Specifically, when applying in a flow cell system, the Faradaic efficiency (FE) of total C2+ products and the selectivity of C2+ liquid products are as high as 81.6% and 49.5%, respectively. Moreover, the current density of C2+ liquid products reaches 196.8 mA cm-2, outperforming most of the reported Cu-based catalysts for CO2RR toward the production of C2+ liquid products. Density functional theory calculations indicate that the synergized Cu/Pb core/shell NCs reduce the formation energies of *COOH and *OCCOH intermediates, as the two critical intermediates for the reduction of CO2 to CO and the formation of C2+ products, respectively, and leads to the significant increase in the selectivity of C2+ liquid products. This study provides a efficient Cu-based catalyst for the reduction of CO2, highlighting the importance of synergistic effect for the design of electrocatalysts in catalysis.

11.
Int J Mol Sci ; 21(24)2020 Dec 09.
Artigo em Inglês | MEDLINE | ID: mdl-33317217

RESUMO

In this study, in vivo animal experiments with 12 nude mice bearing breast-cancer-patient-tissue-derived xenograft (PDX) tumors were performed aiming to verify the imaging capability of a novel miniaturized fluorescence molecular tomography (FMT) endoscope, in combination with targeted nanoparticle-near-infrared (NIR) dye conjugates. Tumor-bearing mice were divided into two groups by systematic injection with urokinase plasminogen activator receptor-targeted (n = 7) and nontargeted (n = 5) imaging nanoprobes as a contrast agent, respectively. Each mouse was imaged at 6, 24, and 48 h following the injection of nanoprobes using the FMT endoscope. The results show that systemic delivery of targeted nanoprobes produced a 4-fold enhancement in fluorescence signals from tumors, compared with tumors that received nontargeted nanoprobes. This study indicates that our miniaturized FMT endoscope, coupled with the targeted nanoparticle-NIR dye conjugates as a contrast agent, has high sensitivity and specificity, and thus great potential to be used for image-guided detection and removal of a primary tumor and local metastatic tumors during surgery.

12.
J Am Chem Soc ; 2020 Dec 29.
Artigo em Inglês | MEDLINE | ID: mdl-33372786

RESUMO

Catalysis by canonical radical S-adenosyl-l-methionine (SAM) enzymes involves electron transfer (ET) from [4Fe-4S]+ to SAM, generating an R3S0 radical that undergoes regioselective homolytic reductive cleavage of the S-C5' bond to generate the 5'-dAdo· radical. However, cryogenic photoinduced S-C bond cleavage has regioselectively yielded either 5'-dAdo· or ·CH3, and indeed, each of the three SAM S-C bonds can be regioselectively cleaved in an RS enzyme. This diversity highlights a longstanding central question: what controls regioselective homolytic S-C bond cleavage upon SAM reduction? We here provide an unexpected answer, founded on our observation that photoinduced S-C bond cleavage in multiple canonical RS enzymes reveals two enzyme classes: in one, photolysis forms 5'-dAdo·, and in another it forms ·CH3. The identity of the cleaved S-C bond correlates with SAM ribose conformation but not with positioning and orientation of the sulfonium center relative to the [4Fe-4S] cluster. We have recognized the reduced-SAM R3S0 radical is a (2E) state with its antibonding unpaired electron in an orbital doublet, which renders R3S0 Jahn-Teller (JT)-active and therefore subject to vibronically induced distortion. Active-site forces induce a JT distortion that localizes the odd electron in a single priority S-C antibond, which undergoes regioselective cleavage. In photolytic cleavage those forces act through control of the ribose conformation and are transmitted to the sulfur via the S-C5' bond, but during catalysis thermally induced conformational changes that enable ET from a cluster iron generate dominant additional forces that specifically select S-C5' for cleavage. This motion also can explain how 5'-dAdo· subsequently forms the organometallic intermediate Ω.

13.
Mol Biol Evol ; 2020 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-33306129

RESUMO

The Red Queen hypothesis depicts evolution as the continual struggle to adapt. According to this hypothesis, new genes, especially those originating from non-genic sequences (i.e., de novo genes), are eliminated unless they evolve continually in adaptation to a changing environment. Here, we analyze two Drosophila de novo miRNAs that are expressed in a testis-specific manner with very high rates of evolution in their DNA sequence. We knocked out these miRNAs in two sibling species and investigated their contributions to different fitness components. We observed that the fitness contributions of miR-975 in D. simulans seem positive, in contrast to its neutral contributions in D. melanogaster, while miR-983 appears to have negative contributions in both species, as the fitness of the knockout mutant increases. As predicted by the Red Queen hypothesis, the fitness difference of these de novo miRNAs indicates their different fates.

14.
J Phys Chem Lett ; : 73-79, 2020 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-33306392

RESUMO

Standard implementations of generalized gradient approximation (GGA)-based density functional theory (DFT) describe well strongly bound molecules and solids but fail to describe long-range London dispersion or van der Waals (vdW) attraction interactions that are important in molecular crystals and two-dimensional solids. To provide accurate values for the vdW distance and energies for the metals Cu, Ag, Au, Ni, Pd, and Pt, we determined empirical vdW corrections to Perdew, Burke, and Ernzerhof (PBE) DFT by fitting the experimental adsorption enthalpies measured by temperature-programmed desorption (TPD) from benzene monolayers by Campbell and co-workers ( J. Phys. Chem. C 2016, 120, 25161-25172). Benzene physisorbed to these metals without chemical reaction; therefore, we consider the bonding to be vdW. We use the low gradient form for the vdW corrections, EvdW-LG = -C6LG/[R6 + RvdwLG6] with just two parameters per atom (C6LG and RvdwLG). This LG form leads to negligible changes in bond distances and angles, so adjusting the parameters should not sacrifice accuracy for the bonding interactions. We demonstrate that the parameters fitted to benzene also describe well the physisorption enthalpies for other hydrocarbons (naphthalene, cyclohexane, methane, ethane, and propane) on Pt. We also report low gradient vdW correction parameters for the noble gases that fit the equilibrium lattice parameter and heat of vaporization of the crystals.

15.
Artigo em Inglês | MEDLINE | ID: mdl-33331055

RESUMO

Bifunctional hydrogen electrocatalysis (hydrogen oxidation and hydrogen evolution reactions) in alkaline solution is desirable but challenging. Among all available electrocatalysts, Ni-based materials are the only non-precious-metal-based candidates for alkaline hydrogen oxidation, but are generally suffered from low activity. Here, we demonstrate that properly alloying Ni with Mo could significantly promote its electrocatalytic performance. Ni 4 Mo alloy nanoparticles are prepared from the reduction of molybdate-intercalated Ni(OH) 2 nanosheets. The final product exhibits apparent hydrogen oxidation activity exceeding that of the Pt benchmark and record-high mass-specific kinetic current of 79 A g -1 at the overpotential of 50 mV. Superior hydrogen evolution performance is also measured in alkaline solution. These experimental data are rationalized by our theoretical simulations, which show that alloying Ni with Mo significantly weakens its hydrogen adsorption, improves the hydroxyl adsorption and decreases the reaction barrier for water formation.

16.
J Integr Plant Biol ; 2020 Dec 17.
Artigo em Inglês | MEDLINE | ID: mdl-33331695

RESUMO

Global warming poses a serious threat to crops. CDPKs/CPKs play vital roles in plant stress responses, but their exact roles in plant thermotolerance remains elusive. Here, we explored the roles of heat-induced ZmCDPK7 in thermotolerance in maize. ZmCDPK7-overexpressing maize plants displayed higher thermotolerance, photosynthetic rates, and antioxidant enzyme activity but lower H2 O2 and malondialdehyde (MDA) contents than wild-type plants under heat stress. ZmCDPK7-knockdown plants displayed the opposite patterns. ZmCDPK7 is attached to the plasma membrane but can translocate to the cytosol under heat stress. ZmCDPK7 interacts with the small heat shock protein sHSP17.4, phosphorylates sHSP17.4 at Ser-44 and the respiratory burst oxidase homolog RBOHB at Ser-99, and upregulates their expression. Site-directed mutagenesis of sHSP17.4 to generate a Ser-44-Ala substitution reduced ZmCDPK7's enhancement of catalase activity but enhanced ZmCDPK7's suppression of MDA accumulation in heat-stressed maize protoplasts. sHSP17.4, ZmCDPK7, and RBOHB were less strongly upregulated in response to heat stress in the abscisic acid-deficient mutant vp5 vs. the wild type. Pretreatment with an RBOH inhibitor suppressed sHSP17.4 and ZmCDPK7 expression. Therefore, abscisic acid-induced ZmCDPK7 functions both upstream and downstream of RBOH and participates in thermotolerance in maize by mediating the phosphorylation of sHSP17.4, which might be essential for its chaperone function. This article is protected by copyright. All rights reserved.

17.
Biosci Rep ; 2020 Dec 04.
Artigo em Inglês | MEDLINE | ID: mdl-33274736

RESUMO

Osteogenic differentiation is an important process of new bone formation, miR-409-3p has been reported to be upregulated in osteogenic differentiation of human bone marrow mesenchymal stem cells (MSCs). To investigate the regulatory effect of miR-409-3p on osteogenic differentiation of MSCs and its molecular mechanism, the expression of miR-409-3p in osteoblast (HCO) and bone marrow-derived MSCs (MSC-A, MSC-B, MSC-U) were detected by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The binding of miR-409-3p to SCAI in MSC-B was investigated by dual-luciferase reporter gene assay. MSC-B were selected to transfect with miR-409-3p analog/complementary sequence (cs), miR-409-3p analog + SCAI and miR-409-3p cs + small interfering (si)-SCAI, as well as control, respectively. The alkaline phosphatase activity, alizarin red staining, and the expression of osteogenic markers in MSC-B during osteoblastic differentiation were tested by RT-qPCR and Western blotting, respectively. The Wnt/ß-catenin pathway was inhibited by dickkopf-related protein 1 to get the roles of miR-409-3p during the osteoblastic differentiation of MSC-B when transfected with miR-409-3p analog. The expression of miR-409-3p in HCO was higher than that in these three MSCs, showing an increasing time-dependent trend on the 0 and 21th day of osteoblastic differentiation. MiR-409-3p directly regulated SCAI by targeting SCAI 3'UTR. Further, miR-409-3p suppressed SCAI expression, but SCAI upregulation suppressed the osteoblastic differentiation, as well as reduced the relative mRNA/protein expression of Wnt/ß-catenin signaling pathway-related genes. Importantly, disruption of Wnt signaling also blocked miR-409-3p induced osteoblastic differentiation of MSCs. Therefore, miR-409-3p promotes osteoblastic differentiation through the activation of the Wnt/ß-catenin pathway by downregulating SCAI expression.

18.
Chem Soc Rev ; 2020 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-33283811

RESUMO

Covalent organic frameworks offer a molecular platform for integrating organic units into periodically ordered yet extended two- and three-dimensional polymers to create topologically well-defined polygonal lattices and built-in discrete micropores and/or mesopores. This polymer architecture is unique as it enables predesigning both primary- and high-order structures, greatly enhancing our capabilities of designing organic materials to produce predictable structures and to achieve unique properties and functions. Progress over the past 15 years in the design, synthesis and functional exploration of COFs has successively established the basis of the COF field and COFs have shown the great potential of chemistry in developing a class of amazing organic materials. In this review, we focus on analysing the historic developments of COFs to uncover a full materials and application picture by providing comprehensive yet clear guidance for molecular design, synthetic control and functional exploration. We scrutinise the structural components of COFs including building blocks, reactive sites and functional groups with the aim of finding the origins of structural designability and diversity, as well as multiple functionalities. We disclose strategies for designing and synthesising frameworks to construct various tailor-made interfaces, and for exploring skeletons and pores to design properties and functions. With well-defined skeletons, pores and interfaces that offer a chemical basis to trigger and control interactions with photons, excitons, phonons, polarons, electrons, holes, spins, ions and molecules, we illustrate the current status of our understandings of structure-property correlations, and unveil the principles for establishing a regime to design unique functions that originate from and are inherent to structures. We predict the key central issues in design and synthesis, the challenges in functional design and the future directions from the perspectives of chemistry, physics and materials science.

19.
Artigo em Inglês | MEDLINE | ID: mdl-33285540

RESUMO

The coupling between the metal-insulator transition (MIT) and the structural phase transition (SPT) in VO2has been at the center of discussion for several decades, while the underlying mechanisms of electron-lattice or electron-electron interactions remain an open question. Until recently, the equilibrium state VO2is believed to be a non-standard Mott-Hubbard system, i.e., both of the two interactions cooperatively work on MIT, indicating the association between MIT and SPT. However, due to the pronounced contribution of strain in strongly correlated systems, it is desirable to explore the correspondence in an interface-engineered VO2. Herein, we investigate the carrier dynamics in highly strained VO2films with anomalous MIT on the basis of time-resolved transient differential reflectivity measurements. Unexpectedly, MIT is decoupled from SPT, in sharp contrast with the case of strain-free VO2films: MIT is triggered by bandgap recombination below 75oC during heating, while intense SPT-induced signal appears separately between 70oC and 100oC. The decoupling between MIT and SPT provides insights into the interfacial interactions in VO2thin films.

20.
PLoS One ; 15(12): e0243789, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33301522

RESUMO

Native intact N-glycopeptide analysis can provide access to the comprehensive characteristics of N-glycan occupancy, including N-glycosites, N-glycan compositions, and N-glycoproteins for complex samples. The sample pre-processing method used for the analysis of intact N-glycopeptides usually depends on the enrichment of low abundance N-glycopeptides from a tryptic peptide mixture using hydrophilic substances before LC-MS/MS detection. However, the number of identified intact N-glycopeptides remains inadequate to achieve an in-depth profile of the N-glycosylation landscape. Here, we optimized the sample preparation workflow prior to LC-MS/MS analysis by systematically comparing different analytical methods, including the use of different sources of trypsin, combinations of different proteases, and different enrichment materials. Finally, we found that the combination of Trypsin (B)/Lys-C digestion and zwitterionic HILIC (Zic-HILIC) enrichment significantly improved the mass spectrometric characterization of intact N-glycopeptides, increasing the number of identified intact N-glycopeptides and offering better analytical reproducibility. Furthermore, the optimized workflow was applied to the analysis of intact N-glycopeptides in two-dimensional (2D) and three-dimensional (3D)-cultured breast cancer cells in vitro and xenografted tumors in mice. These results indicated that the same breast cancer cells, when cultured in different microenvironments, can show different N-glycosylation patterns. This study also provides an interesting comparison of the N-glycoproteome of breast cancer cells cultured in different growth conditions, indicating the important role of N-glycosylated proteins in cancer cell growth and the choice of the cell culture model for studies in tumor biology and drug evaluation.

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