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1.
J Mater Chem B ; 2020 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-33034309

RESUMO

A 2D CuNi metal-organic framework (MOF) named CuxNi3-x(HHTP)2 was synthesized with 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP) as the linker and was used as a sensitive scaffold to adsorb aptamer strands for the electrochemical detection of living C6 glioma cells and one of their biomarkers, epidermal growth factor receptor (EGFR). Different from conventional MOFs, the CuxNi3-x(HHTP)2 MOF comprises long-range delocalized electrons, a graphene-analog nanostructure, multiple metal states (Cu0/Cu+/Cu2+ and Ni2+/Ni3+), and abundant oxygen vacancies. With these features, the CuxNi3-x(HHTP)2 MOF anchored a large amount of C6 cell-targeted aptamer strands via coordination among metal centers, oligonucleotides, π-π stacking, and van der Waals force. The CuxNi3-x(HHTP)2-based cytosensor showed a low limit of detection (LOD) of 21 cells mL-1 toward C6 glioma cells within a wide range from 50 cells mL-1 to 1 × 105 cells mL-1. Moreover, the proposed aptasensor displayed high selectivity, good stability, acceptable reproducibility, and a low LOD of 0.72 fg mL-1 for detecting EGFR with the concentration ranging from 1 fg mL-1 to 1 ng mL-1. The aptasensor based on the CuxNi3-x(HHTP)2 MOF exhibited superior sensing performance over those based on its monometallic analogues such as Cu3(HHTP)2 MOF and Ni3(HHTP)2 MOF. Hence, this sensing strategy based on a bimetallic semiconducting MOF shows great potential for cancer diagnosis.

2.
Inflammopharmacology ; 28(6): 1481-1493, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33006110

RESUMO

Gout, the most prevalent inflammatory arthritis worldwide, released interleukin-1ß (IL-1ß) and Cathepsin B inflammatory mediators that constitute the hallmark of the disease. Herein we aimed to investigate whether procyanidin B2 (PCB2), a natural dietary compound, can suppress MSU crystals-stimulated gouty inflammation. Treated with lipopolysaccharide (LPS) plus MSU, both mouse peritoneal macrophages (MPM) and mouse bone marrow-derived macrophages (BMDM) released a large amount of mature IL-1ß compared to those treated with MSU or LPS alone, while IL-1ß release was blocked by TLR4 and its downstream effector inhibitors. In two mouse models of gout, oral administration of PCB2 suppressed MSU crystals-induced increasing expression of IL-1ß, Cathepsin B and NLRP3 in the air pouch skin and paws, accompanied with the downregulation prostaglandin E2 (PGE2) in pouch exudates. Inflammatory immune cell infiltration including macrophages and neutrophils were significantly blocked by PCB2 in air pouch skin and paws of mice gout groups. PCB2 also suppressed the release of IL-1ß and Cathepsin B induced by MSU plus LPS in MPM. Our results suggest that the inhibitory effects of PCB2 on NLRP3 inflammasome may alleviate inflammatory response in gout, and this might be a promising anti-inflammatory mechanism of PCB2 against the inflammation in gout.

3.
Artigo em Inglês | MEDLINE | ID: mdl-33048762

RESUMO

The structure of networks can be efficiently represented using motifs, which are those subgraphs that recur most frequently. One route to understanding the motif structure of a network is to study the distribution of subgraphs using statistical mechanics. In this article, we address the use of motifs as network primitives using the cluster expansion from statistical physics. By mapping the network motifs to clusters in the gas model, we derive the partition function for a network, and this allows us to calculate global thermodynamic quantities, such as energy and entropy. We present analytical expressions for the number of certain types of motifs, and compute their associated entropy. We conduct numerical experiments for synthetic and real-world data sets and evaluate the qualitative and quantitative characterizations of the motif entropy derived from the partition function. We find that the motif entropy for real-world networks, such as financial stock market networks, is sensitive to the variance in network structure. This is in line with recent evidence that network motifs can be regarded as basic elements with well-defined information-processing functions.

4.
Plant Biotechnol J ; 2020 Aug 09.
Artigo em Inglês | MEDLINE | ID: mdl-32885918

RESUMO

Salt stress dramatically impedes plant growth and development as well as crop yield. The apple production regions are reduced every year, because of the secondary salt damage by improper fertilization and irrigation. To expand the cultivation area of apple (Malus domestica) and select salt-resistant varieties, the mechanism of salt tolerance in apple is necessary to be clarified. The miR156/SPL regulatory module plays key roles in embryogenesis, morphogenesis, life cycle stage transformation, flower formation and other processes. However, its roles in the mechanisms of salt tolerance are unknown. In order to elucidate the mechanism of 156/SPL regulating salt stress in apple, we performed RLM-5' RACE and stable genetic transformation technology to verify that both mdm-MIR156a and MdSPL13 responded to salt stress in apple and that the latter was the target of the former. MIR156a overexpression weakened salt resistance in apple whereas MdSPL13 overexpression strengthened it. A total of 6094 differentially expressed genes relative to nontransgenic apple plants were found by RNA-Seq analysis of MdSPL13OE. Further verification indicated that MdSPL13 targeted the MdWRKY100 gene promoter. Moreover, MdWRKY100 overexpression enhanced salt tolerance in apple. Our results revealed that the miR156/SPL module regulates salt tolerance by up-regulating MdWRKY100 in apple. This study is the first to elucidate the mechanism underlying the miRNA network response to salt stress in apple and provides theoretical and empirical bases and genetic resources for the molecular breeding of salt tolerance in apple.

6.
Food Funct ; 11(9): 7681-7695, 2020 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-32901642

RESUMO

Lactic acid bacteria strain (LAB) NCU116 fermented Asparagus officinalis polysaccharides (FAOP) have been proven to cause substantial changes in physicochemical properties such as monosaccharide composition and molecular weight, accounting for their enhanced immune activity than unprocessed Asparagus officinalis polysaccharides (AOP). In the current study, the hepatoprotective effects of FAOP in mice with cyclophosphamide (CTX)-induced hepatotoxicity were investigated. FAOP were more effective than AOP in alleviating CTX-induced hepatic damage, including inhibition of hepatic biochemical markers (ALT, AST, AKP and LDH) and pro-inflammatory cytokines (TNF-α and IL-1ß) as well as reinforcement of antioxidant systems (T-AOC, SOD, CAT, and MDA). In particular, compared with AOP, FAOP showed superior performance by promoting GSH biosynthesis, and normalizing the expression level of bile acid receptors (FXR and SHP) and key enzymes in bile acid synthesis (CYP7A1, CYP8B1 and CYP27A1). Modulation of disordered homeostasis of bile acids by FAOP can be attributed to the upregulation of hepatic short chain fatty acid (SCFA) receptors GPR41 and GPR109A as well as intestinal SCFA production. Furthermore, serum metabolomics study validated the hepatoprotective superiority of FAOP than AOP with evidence from variations in bile acid compositions and the construction of related metabolic pathways. Therefore, LAB NCU116 fermentation of Asparagus officinalis was practical and effective to obtain promising hepatoprotective polysaccharides, which might arise from enhanced SCFA production than unprocessed AOP.

7.
Disaster Med Public Health Prep ; : 1-22, 2020 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-32782044

RESUMO

Since the outbreak of 2019 novel coronavirus infection (2019-nCoV) in Wuhan City, China, pediatric cases have gradually increase. It is very important to prevent cross-infection in pediatric fever clinics, how identify children with fever in pediatric fever clinics, and strengthen the management of pediatric fever clinics. According to prevention and control programs, we propose the guidance on the management of pediatric fever clinics during the novel coronavirus pneumonia epidemic period, which outlines in detail optimizes processes, prevents cross-infection, health protection and disinfection of medical staff. The present consideration statement summarizes current strategies on pre-diagnosis, triage, diagnosis, treatment, and prevention of 2019-nCoV infection, which provide practical suggestions on strengthening the management of pediatric fever clinics during the novel coronavirus pneumonia epidemic period.

8.
Spine (Phila Pa 1976) ; 45(20): E1296-E1301, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32796464

RESUMO

STUDY DESIGN: A scanning electron microscopic study performed on three cadaveric specimens focused on the human suboccipital region, specifically, myodural bridge (MDB). OBJECTIVE: This study showed the connection form of the MDB among the suboccipital muscles, the posterior atlanto-occipital membrane (PAOM) and the spinal dura mater (SDM), and provided an ultrastructural morphological basis for the functional studies of the MDB. SUMMARY OF BACKGROUND DATA: Since the myodural bridge was first discovered by Hack, researches on its morphology and functions had been progressing continuously. However, at present, research results about MDB were still limited to the gross anatomical and histological level. There was no research report showing the MDB's ultrastructural morphology and its ultrastructural connection forms between PAOM and SDM. METHODS: A scanning electron microscope (SEM) was used to observe the connection of myodural bridge fibers with PAOM and SDM in atlanto-occipital and atlanto-axial interspaces, and the connection forms were analyzed. RESULTS: Under the SEM, it was observed that there were clear direct connections between the suboccipital muscles and the PAOM and SDM in the atlanto-occipital and atlanto-axial spaces. These connections were myodural bridge. The fibers of the myodural bridge merged into the spinal dura mater and gradually became a superficial layer of the spinal dura mater. CONCLUSION: MDB fibers merged into the SDM and became part of the SDM in the atlanto-occipital and atlanto-axial space. MDB could transfer tension and pulling force to the SDM effectively, during the contraction or relaxation of the suboccipital muscles. LEVEL OF EVIDENCE: N/A.

9.
ACS Nano ; 14(9): 12125-12132, 2020 09 22.
Artigo em Inglês | MEDLINE | ID: mdl-32808759

RESUMO

This article reports on a noninvasive approach in detecting and following-up individuals who are at-risk or have an existing COVID-19 infection, with a potential ability to serve as an epidemic control tool. The proposed method uses a developed breath device composed of a nanomaterial-based hybrid sensor array with multiplexed detection capabilities that can detect disease-specific biomarkers from exhaled breath, thus enabling rapid and accurate diagnosis. An exploratory clinical study with this approach was examined in Wuhan, China, during March 2020. The study cohort included 49 confirmed COVID-19 patients, 58 healthy controls, and 33 non-COVID lung infection controls. When applicable, positive COVID-19 patients were sampled twice: during the active disease and after recovery. Discriminant analysis of the obtained signals from the nanomaterial-based sensors achieved very good test discriminations between the different groups. The training and test set data exhibited respectively 94% and 76% accuracy in differentiating patients from controls as well as 90% and 95% accuracy in differentiating between patients with COVID-19 and patients with other lung infections. While further validation studies are needed, the results may serve as a base for technology that would lead to a reduction in the number of unneeded confirmatory tests and lower the burden on hospitals, while allowing individuals a screening solution that can be performed in PoC facilities. The proposed method can be considered as a platform that could be applied for any other disease infection with proper modifications to the artificial intelligence and would therefore be available to serve as a diagnostic tool in case of a new disease outbreak.

10.
Plant Cell Rep ; 39(11): 1479-1491, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32761275

RESUMO

KEY MESSAGE: MdHAL3 has PPCDC activity and is involved in the salt tolerance of autotetraploid apple. Apple (Malus × domestica) is the most widely planted fruit tree species worldwide. However, the growth and development of apple have been increasingly affected by abiotic stress, such as high salinity. In our previous study, RNA sequencing (RNA-seq) analysis revealed that the expression level of the MdHAL3 gene was significantly upregulated in the autotetraploid apple cultivar Hanfu. In the present study, we first isolated HAL3, whose product was shown to exert 4'-phosphopantothenoylcysteine decarboxylase (PPCDC) activity, from apple. MdHAL3 was expressed in all organs of apple, and its expression was rapidly induced by salt stress. The MdHAL3 protein was localized to the cytomembrane and cytoplasm. Five MdHAL3 overexpression (OE) lines and five MdHAL3-RNAi apple lines were obtained. We found that MdHAL3 enhanced the salt stress tolerance of apple and that the OE plants rooted more easily than the wild-type (WT) plants. The coenzyme A (CoA) content in the leaves of the OE plants was greater than that in the leaves of the WT plants, and the CoA content in the MdHAL3-RNAi plants was lower than that in the WT plants. Taken together, our findings indicate that MdHAL3 plays an essential role in the response to salt stress in apple.

11.
BMC Bioinformatics ; 21(1): 355, 2020 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-32787776

RESUMO

BACKGROUND: The accurate annotation of protein functions is of great significance in elucidating the phenomena of life, treating disease and developing new medicines. Various methods have been developed to facilitate the prediction of these functions by combining protein interaction networks (PINs) with multi-omics data. However, it is still challenging to make full use of multiple biological to improve the performance of functions annotation. RESULTS: We presented NPF (Network Propagation for Functions prediction), an integrative protein function predicting framework assisted by network propagation and functional module detection, for discovering interacting partners with similar functions to target proteins. NPF leverages knowledge of the protein interaction network architecture and multi-omics data, such as domain annotation and protein complex information, to augment protein-protein functional similarity in a propagation manner. We have verified the great potential of NPF for accurately inferring protein functions. According to the comprehensive evaluation of NPF, it delivered a better performance than other competing methods in terms of leave-one-out cross-validation and ten-fold cross validation. CONCLUSIONS: We demonstrated that network propagation, together with multi-omics data, can both discover more partners with similar function, and is unconstricted by the "small-world" feature of protein interaction networks. We conclude that the performance of function prediction depends greatly on whether we can extract and exploit proper functional information of similarity from protein correlations.


Assuntos
Algoritmos , Biologia Computacional/métodos , Mapas de Interação de Proteínas , Análise por Conglomerados , Ontologia Genética , Ligação Proteica , Reprodutibilidade dos Testes , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo
12.
Mikrochim Acta ; 187(8): 436, 2020 07 09.
Artigo em Inglês | MEDLINE | ID: mdl-32648043

RESUMO

The synthesis of hierarchical NiCo2O4-CoNiO2 hybrids embedded in partially reduced graphene oxide (represented by NiCo2O4/CoNiO2@pPRGO) is described. They were derived from ultrathin CoNi-based zeolitic imidazolate framework (CoNi-ZIF) nanosheets vertically grew on three-dimensional (3D) pRGO networks by pyrolysis at different temperatures (300, 600, and 900 °C) in N2 atmosphere. Transmission electron microscopy, X-ray diffraction, and X-ray photoemission spectroscopy measurements showed that the metal coordination centers (Co or Ni) were transferred into NiCo2O4 spinel and CoNiO2 nanostructures, along with a small number of metallic states of Co and Ni. In view of good electrochemical conductivity and large specific surface area of pRGO, good catalytic activity of Co- and Ni-contained NPs, and homogeneous distribution of NPs within the pRGO network, the NiCo2O4/CoNiO2@pRGO600 nanohybrid calcined at 600 °C displayed superior electrocatalytic activity toward hydrogen peroxide (H2O2) reduction. A glassy carbon electrode modified with NiCo2O4/CoNiO2@pRGO600 was used for determination of H2O2 by amperometry at an applied potential of - 0.4 V vs. Ag/AgCl. The nonenzymatic amperometric sensor exhibited high sensitivity and low detection limit (0.41 µM) within a wide working range (5 µM-3 mM and 3-12 mM) toward H2O2, as well as good selectivity, reproducibility, and long-term stability. Benefiting from the good biocompatibility and remarkable analytical performances of NiCo2O4/CoNiO2@pRGO600, the assay was used to determine real-time H2O2 released from living cancer cells. Graphical abstract.

13.
Artigo em Inglês | MEDLINE | ID: mdl-32692680

RESUMO

Network representations are powerful tools to modeling the dynamic time-varying financial complex systems consisting of multiple co-evolving financial time series, e.g., stock prices. In this work, we develop a novel framework to compute the kernel-based similarity measure between dynamic time-varying financial networks. Specifically, we explore whether the proposed kernel can be employed to understand the structural evolution of the financial networks with time associated with standard kernel machines. For a set of time-varying financial networks with each vertex representing the individual time series of a different stock and each edge between a pair of time series representing the absolute value of their Pearson correlation, our start point is to compute the commute time (CT) matrix associated with the weighted adjacency matrix of the network structures, where each element of the matrix can be seen as the enhanced correlation value between pairwise stocks. For each network, we show how the CT matrix allows us to identify a reliable set of dominant correlated time series as well as an associated dominant probability distribution of the stock belonging to this set. Furthermore, we represent each original network as a discrete dominant Shannon entropy time series computed from the dominant probability distribution. With the dominant entropy time series for each pair of financial networks to hand, we develop an entropic dynamic time warping kernels through the classical dynamic time warping framework, for analyzing the financial time-varying networks. We show that the proposed kernel bridges the gap between graph kernels and the classical dynamic time warping framework for multiple financial time series analysis. Experiments on time-varying networks extracted through New York Stock Exchange (NYSE) database demonstrate that the effectiveness of the proposed method.

14.
Neurol Res ; 42(8): 693-702, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32657248

RESUMO

It has been established that poor outcomes in ischemic stroke patients are associated with the post-reperfusion inflammatory response and up-regulation of TLR4. Therefore, suppression of the TLR4 signaling pathway constitutes a potential neuroprotective therapeutic strategy. Schisandrin B, a compound extracted from Schisandra chinensis, has been shown to possess anti-inflammatory and neuroprotective properties. However, the mechanism remains unclear. In the present study, the therapeutic effect of schisandrin B was assessed following cerebral ischemia and reperfusion (I/R) injury in a model of middle cerebral artery occlusion and reperfusion (MCAO/R) in rats. The effects of schisandrin B were investigated with particular emphasis on TLR4 signal transduction and on the inflammatory response. Schisandrin B treatment conferred significant protection against MCAO/R injury, as evidenced by decreases in infarct volume, neurological score, and the number of apoptotic neurons and inflammatory signaling molecules. ABBREVIATIONS: I/R: schemia/reperfusion; IL: interleukin; MCAO/R: middle cerebral artery occlusion and reperfusion; NF-κB: nuclear; TLR4: Toll-like receptor 4; TNF-α: tumor necrosis factor-α.

15.
Plant Physiol ; 184(1): 176-193, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32636342

RESUMO

Actin binding proteins and transcription factors are essential in regulating plant root hair growth in response to various environmental stresses; however, the interaction between these two factors in regulating root hair growth remains poorly understood. Apical and subapical thick actin bundles are necessary for terminating rapid elongation of root hair cells. Here, we show that Arabidopsis (Arabidopsis thaliana) actin-bundling protein Villin1 (VLN1) decorates filaments in shank, subapical, and apical hairs. vln1 mutants displayed significantly longer hairs with longer hair growing time and defects in the thick actin bundles and bundling activities in the subapical and apical regions, whereas seedlings overexpressing VLN1 showed different results. Genetic analysis showed that the transcription factor GLABRA2 (Gl2) played a regulatory role similar to that of VLN1 in hair growth and actin dynamics. Moreover, further analyses demonstrated that VLN1 overexpression suppresses the gl2 mutant phenotypes regarding hair growth and actin dynamics; GL2 directly recognizes the promoter of VLN1 and positively regulates VLN1 expression in root hairs; and the GL2-mediated VLN1 pathway is involved in the root hair growth response to osmotic stress. Our results demonstrate that the GL2-mediated VLN1 pathway plays an important role in the root hair growth response to osmotic stress, and they describe a transcriptional mechanism that regulates actin dynamics and thereby modulates cell tip growth in response to environmental signals.

16.
Plant Physiol ; 184(1): 283-299, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32661060

RESUMO

The thylakoid membrane is a highly complex membrane system in plants and plays crucial roles in the biogenesis of the photosynthetic apparatus and plant development. However, the genetic factors involved in chloroplast development and its relationship with intracellular metabolites are largely unknown. Here, a rice (Oryza sativa) chlorotic and necrotic leaf1 (cnl1) mutant was identified and map-based cloning revealed that a single base substitution followed by a 6-bp deletion in the ATP-binding cassette transporter I family member7 (OsABCI7) resulted in chlorotic and necrotic leaves with thylakoid membrane degradation, chlorophyll breakdown, photosynthesis impairment, and cell death in cnl1 Furthermore, the expression of OsABCI7 was inducible under lower temperatures, which severely affected cnl1 chloroplast development, and etiolated cnl1 seedlings were unable to recover to a normal green state under light conditions. Functional complementation and overexpression showed that OsABCI7 could rescue the cnl1 chlorotic and necrotic phenotype. OsABCI7 interacted with HIGH CHLOROPHYLL FLUORESCENCE222 (OsHCF222) to regulate cellular reactive oxygen species (ROS) homeostasis for thylakoid membrane stability. OsABCI7 localized to thylakoid membranes, while OsHCF222 targeted to endoplasmic reticulum and chloroplasts. Exogenous application of ascorbic acid eased the yellowish leaf phenotype by increasing chlorophyll content and alleviating ROS stress in cnl1 Unlike cnl1, the CRISPR/Cas9-mediated OsHCF222 knockout lines showed chlorotic leaves but were seedling lethal. Our results provide insight into the functions of ABC transporters in rice, especially within the relationship between ROS homeostasis and stability of thylakoid membranes.

17.
Pathol Int ; 70(10): 798-803, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32716129

RESUMO

A 34-year-old Chinese woman found a lump in her left leg for more than 3 weeks without any discomfort. Grossly, the tumor was relatively well delineated with focal infiltration. Histopathologic evaluation showed a compact fascicular spindle cell proliferation with variable myxoid and collagenous stroma and scattered inflammatory infiltrate. Immunohistochemically, the tumor cells showed positive expression of ALKD5F3 and SMA and negative expression of CD34, desmin, and cytokeretin. Fluorescence in situ hybridization analysis of the ALK locus showed break-apart signals in 20% of tumor cells, and DNA sequencing discovered a novel CLIP2-ALK fusion gene. The lesion was diagnosed as an inflammatory myofibroblastic tumor (IMT). To the best of our knowledge, this is the first case with CLIP2-ALK gene fusion in the somatic soft tissue IMTs.

18.
Nanotechnology ; 31(44): 444001, 2020 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-32585644

RESUMO

In semiconductor nanowire (NW) photodetectors, the Schottky barrier formed by the contact between metal and semiconductor can act as a depletion layer. For NW structures with a smaller diameter, the depletion region is especially important to the carrier transport. We prepared a GaAs/AlGaAs quantum well NW photodetector with a two-dimensional electron-hole tube, in which the two-dimensional hole tube (2DHT) formed by the inner layer of GaAs and AlGaAs has the most important role in the regulation of carriers. By adjusting the bias voltage to vary the depth of the depletion region, we have confirmed the influence of the depletion region in a 2DHT. A significant inflection point was found in the responsivity-voltage curve at 1.5 V. By combining the depletion region and 2DHT, the responsivity of the fabricated device was increased by 18 times to 0.199 A W-1 and the detectivity is increased by 5 times to 5.8 × 1010 Jones, compared to the pure GaAs NW photodetector. Reasonable combination of depletion layer and 2DHT was proved to promote high-performance NW photodetector.

19.
J Colloid Interface Sci ; 578: 10-23, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32504902

RESUMO

As the efficient approaches for obtaining clean H2 energy, methanol oxidation (MOR) and water over slitting reactions have been increasingly essential. A series of novel semiconductive CoNi bimetal-organic framework (CoxNi3-x(HAB)2 MOF) have been prepared using hexaaminobenzene (HAB) as an organic linker. The obtained series of CoxNi3-x(HAB)2 MOFs were then explored as efficient multifunctional electrocatalysts for the non-Pt MOR and overall water splitting in alkaline medium. The basic characterizations of CoxNi3-x(HAB)2 MOFs revealed that they comprised multiple metal valence states (Co0/Co2+/Co3+ and Ni2+/Ni3+) and graphene-like nanostructures embedded with abundant CoNi alloy nanoparticles. Compared with the sole-metal MOFs (Co3(HAB)2 MOF and Ni3(HAB)2 MOF), the CoxNi3-x(HAB)2 MOF with a mass ratio of Co:Ni = 1:3 (CoxNi3-x(HAB)2 MOF-2) exhibited superior electrocatalytic performance for MOR. It gave a high current density of 92.8 mA cm-2 at 1.6 V vs. reversible hydrogen electrode (RHE) for MOR, along with the low overpotentials at the current density of 10 mV cm-2 (η10) and Tafel slopes toward hydrogen evolution reaction (η10 = 119 mV, Tafel slope = 46 mV dec-1) and oxygen evolution reaction (η10 = 1.35 V, Tafel slope = 26 mV dec-1). The analysis on the catalysis mechanism of MOR and water splitting in alkaline medium was also proposed. The voltages applied to the three- and two-electrode systems based on the bifunctional CoxNi3-x(HAB)2 MOF-2 catalyst for overall water splitting are 1.52 V vs. RHE and 1.45 V vs. silver/silver chloride (Ag/AgCl), respectively. This work provides a novel strategy for investigating the applications of promising two-dimensional semiconductive MOF as multifunctional electrocatalysts with boosted electrocatalytic activities in energy fields.

20.
Langmuir ; 36(26): 7190-7199, 2020 07 07.
Artigo em Inglês | MEDLINE | ID: mdl-32529830

RESUMO

Synergy between antimicrobial peptides PGLa and Magainin 2 (MAG2) provides an efficient way to enhance their antimicrobial ability. However, the underlying molecular mechanism of such synergy, especially the individual roles of each peptide, remains poorly understood. We combined a giant unilamellar vesicle leakage assay, in situ interfacial photovoltage testing, and molecular dynamics to investigate membrane poration under the action of PGLa, MAG2, or a PGLa/MAG2 mixture. Our results clearly show the different membrane action modes of the three systems and demonstrate the importance of forming PGLa-MAG2 heterodimers in the membrane poration process. PGLa inserted into and extracted from a membrane rapidly and continually with minimal aggregation and produced only transient, small pores. In contrast, MAG2 peptides tended to aggregate together on the membrane surface or only shallowly embed in the membrane. Additionally, the PGLa and MAG2 residues were well integrated into the membrane via the formation of PGLa-MAG2 heterodimers. The membrane defect produced by the rapid insertion of PGLa was stabilized by MAG2, which further recruited other peptides for the formation of PGLa-MAG2 heterodimers and even heterodimer clusters. Growth in pore size then occurred in a step-by-step process involving the formation and assembly of heterodimer clusters within the membrane. Our results provide insight into the complicated synergy that occurs between PGLa and MAG2 during membrane poration and will assist in the design of new antimicrobial peptides.

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