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1.
Cell Death Dis ; 12(5): 448, 2021 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-33953172

RESUMO

Osteoarthritis (OA) is the most common chronic joint disease in the elderly population. Growing evidence indicates that a balance between autophagy and apoptosis in chondrocytes plays a key role in OA's cartilage degradation. Thus, drugs targeting the balance between apoptosis and autophagy are potential therapeutic approaches for OA treatment. In previous studies, we found that the activation of α7 nicotinic acetylcholine receptors (α7-nAChRs) alleviated monosodium iodoacetate (MIA)-induced joint degradation and osteoarthritis pain. To explore the potential functions of α7-nAChRs in autophagy and apoptosis signaling in knee OA, we compared the expression of α7-nAChRs in human knee articular cartilage tissues from normal humans and OA patients. We found that knee joint cartilage tissues of OA patients showed decreased α7-nAChRs and an imbalance between autophagy and apoptosis. Next, we observed that α7-nAChRs deficiency did not affect cartilage degradation in OA development but reversed the beneficial effects of nicotine on mechanical allodynia, cartilage degradation, and an MIA-induced switch from autophagy to apoptosis. Unlike in vivo studies, we found that primary chondrocytes from α7-nAChRs knockout (KO) mice showed decreased LC3 levels under normal conditions and were more sensitive toward MIA-induced apoptosis. Finally, we found that α7-nAChRs deficiency increased the phosphorylation of mTOR after MIA treatment, which can also be observed in OA patients' tissues. Thus, our findings not only confirmed that nicotine alleviated MIA-induced pain behavior and cartilage degradation via stimulating the α7-nAChRs/mTOR signal pathway but found the potential role of α7-nAChRs in mediating the balance between apoptosis and autophagy.

2.
Artigo em Inglês | MEDLINE | ID: mdl-33955709

RESUMO

BACKGROUND: Satellite cells (SCs) are critical to skeletal muscle regeneration. Inactivation of SCs is linked to skeletal muscle loss. Transferrin receptor 1 (Tfr1) is associated with muscular dysfunction as muscle-specific deletion of Tfr1 results in growth retardation, metabolic disorder, and lethality, shedding light on the importance of Tfr1 in muscle physiology. However, its physiological function regarding skeletal muscle ageing and regeneration remains unexplored. METHODS: RNA sequencing is applied to skeletal muscles of different ages to identify Tfr1 associated to skeletal muscle ageing. Mice with conditional SC ablation of Tfr1 were generated. Between Tfr1SC/WT and Tfr1SC/KO (n = 6-8 mice per group), cardiotoxin was intramuscularly injected, and transverse abdominal muscle was dissected, weighted, and cryosectioned, followed by immunostaining, haematoxylin and eosin staining, and Masson staining. These phenotypical analyses were followed with functional analysis such as flow cytometry, tread mill, Prussian blue staining, and transmission electron microscopy to identify pathological pathways that contribute to regeneration defects. RESULTS: By comparing gene expression between young (2 weeks old, n = 3) and aged (80 weeks old, n = 3) mice among four types of muscles, we identified that Tfr1 expression is declined in muscles of aged mice (~80% reduction, P < 0.005), so as to its protein level in SCs of aged mice. From in vivo and ex vivo experiments, Tfr1 deletion in SCs results in an irreversible depletion of SCs (~60% reduction, P < 0.005) and cell-autonomous defect in SC proliferation and differentiation, leading to skeletal muscle regeneration impairment, followed by labile iron accumulation, lipogenesis, and decreased Gpx4 and Nrf2 protein levels leading to reactive oxygen species scavenger defects. These abnormal phenomena including iron accumulation, activation of unsaturated fatty acid biosynthesis, and lipid peroxidation are orchestrated with the occurrence of ferroptosis in skeletal muscle. Ferroptosis further exacerbates SC proliferation and skeletal muscle regeneration. Ferrostatin-1, a ferroptosis inhibitor, could not rescue ferroptosis. However, intramuscular administration of lentivirus-expressing Tfr1 could partially reduce labile iron accumulation, decrease lipogenesis, and promote skeletal muscle regeneration. Most importantly, declined Tfr1 but increased Slc39a14 protein level on cellular membrane contributes to labile iron accumulation in skeletal muscle of aged rodents (~80 weeks old), leading to activation of ferroptosis in aged skeletal muscle. This is inhibited by ferrostatin-1 to improve running time (P = 0.0257) and distance (P = 0.0248). CONCLUSIONS: Satellite cell-specific deletion of Tfr1 impairs skeletal muscle regeneration with activation of ferroptosis. This phenomenon is recapitulated in skeletal muscle of aged rodents and human sarcopenia. Our study provides mechanistic information for developing novel therapeutic strategies against muscular ageing and diseases.

3.
Phytochemistry ; 187: 112762, 2021 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-33940379

RESUMO

Seven previously undescribed sesterterpenes were characterized from Penicillium roqueforti YJ-14 by solid fermentation. Their structures were initially investigated in detail by spectroscopic analyses and HR-ESI-MS and were further confirmed by X-crystallography. In in vitro bioassays, compounds 1, 5 and 7 showed cytotoxic activity against the MCF-7 breast cancer cell line with IC50 values of 7.98 ±â€¯0.93, 6.42 ±â€¯0.41 and 7.32 ±â€¯0.18 µM, respectively. Compounds 5 and 7 displayed significant cytotoxicity against the A549 lung cancer cell line (IC50 values of 4.83 ±â€¯0.22 µM and 4.58 ±â€¯0.85 µM, respectively). In addition, compound 5 showed an obvious inhibitory effect on nitric oxide production in LPS-activated RAW264.7 macrophages with an IC50 value of 9.53 ±â€¯0.16 µM.

4.
Artigo em Inglês | MEDLINE | ID: mdl-33942454

RESUMO

π-Stacked dendrimers consisting of cofacially aligned donors and acceptors are developed by introducing three dendritic teracridan donors with orthogonal configuration and three triazine acceptors in periphery of hexaphenylbenzene skeleton. The dendritic structure and orthogonal configuration of teracridan not only make their outer acridan segments approaching to acceptor in close distance, but also fix donor and acceptor in face-to-face alignment, leading to through-space charge transfer emission with thermally activated delayed fluorescence (TADF) effect. By regulating charge transfer strength via substituent effect of acceptor, emission color of the dendrimers can be tuned from blue to yellow/red region. Solution-processed two-color white organic light-emitting diodes (OLEDs) based on blue and yellow π-stacked donor-acceptor dendrimers exhibit the maximum external quantum efficiency of 20.6% and maximum power efficiency of 58.9 lm W -1 , representing the state-of-the-art efficiency for all-TADF white OLEDs by solution process.

5.
Talanta ; 230: 122348, 2021 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-33934797

RESUMO

Carbohydrates are an indispensable part of early life evolution. The determination of their structures is a key step to analyze their critical roles in biological systems. A variation of composition, glycosidic linkage, and (or) configuration between carbohydrate isomers induces structure diversity and brings challenges for their structural determination. Ion mobility spectrometry (IMS), an emerging gas-phase ion separation technology, has been considered as a promising tool for performing carbohydrate structure elucidation. In this work, eight disaccharides were analyzed by trapped ion mobility spectrometry-mass spectrometry (TIMS-MS) in the negative ion mode as the complexed form of [M + X]-, where M = disaccharide, and X = Cl, Br, and I. As compared to the positive ion analysis of the selected disaccharide in a sodiated form, a reversal charge state provided the ability to eliminate or even reverse the collision cross section (CCS) difference between disaccharide isomers. By the combination of TIMS analysis and the calculation of density functional theory, the only observed two conformers of ions [lactulose + I]- may result from different adduction sites for an iodide anion. Based on the comparison of different halogen adducts, the [M + I]- ion form exhibited more powerful ability for isomeric disaccharide differentiation with an average resolution (RP-P) of 1.17, which results in a 34.5% improvement as compared to the corresponding chloride adducts. This result indicates that the use of negative charge states, especially the complexation of an iodide anion, could be a supplemental strategy to commonly used positive ion analysis for carbohydrate separation.

6.
Sci Total Environ ; 783: 146969, 2021 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-33866158

RESUMO

Microplastics pollution in nearshore marine environment has become increasingly prominent and has received widespread attention. As a major leisure and entertainment place in coastal cities, bathing beaches not only provide an environment for microplastics to enter the ocean, but also provide a place for the retention of microplastics. In this paper, the distribution, composition and seasonal variation of microplastics in seawater and sediments of six bathing beaches along the coast of Qingdao were studied. The results showed that the average abundance of microplastics in the sediments of the Qingdao bathing beach was 91.11 ± 26.76 items/m2 (13.77 ± 4.39 items/kg) in the winter and 147.78 ± 34.80 items/m2 (21.98 ± 5.97 items/kg) in the summer. The microplastic abundance in the seawater in the summer (average: 567.50 ± 101.06 items/m3) was significantly higher than that in the winter (average: 326.11 ± 49.03 items/m3, p < 0.05). The abundance of microplastics at the six bathing beaches increased from east to west, consistent with the transport direction of coastal currents. The microplastic abundance in the sediment of non-swimming zone of the bathing beach was significantly higher than that in swimming zone (p < 0.05), and the microplastic abundance in the seawater of the swimming zone was slightly higher than that of the non-swimming zone but with no significant difference (p > 0.05). To an extent, it can reflect the correlation between the abundance of microplastics and human recreational activities. The microplastics detected at the bathing beaches were mainly lines (80.5%) and fragments (7.9%) with a size range of 100 to 1000 µm. Rayon (41.8%) and polyethylene terephthalate (PET, 16.9%) were the main polymer types. The microplastic characteristics showed significant seasonal differences, more diversity in summer than in winter. These results emphasized that the distribution and movement of microplastics in bathing beaches were affected by seasons, human activities and coastal currents.

7.
Artigo em Inglês | MEDLINE | ID: mdl-33809308

RESUMO

There are different ways to deliver Cognitive Behavioral Therapy for Insomnia (CBT-I), of which in-person (face to face) is the traditional delivery method. However, the scalability of in-person therapy is low. Digital Cognitive Behavioral Therapy for Insomnia (dCBT-I) is an alternative and there are tools on the market that are validated in clinical studies. In this paper, we provide a review of the existing evidence-based CBT-I apps and a summary of the published usability-oriented studies of these apps. The goal is to explore the range of interaction methods commonly applied in dCBT-I platforms, the potential impact for the users, and the design elements applied to achieve engagement. Six commercially available CBT-I apps tested by scientifically valid methods were accessed and reviewed. Commonalities were identified and categorized into interactive elements, CBT-I-related components, managerial features, and supportive motivational features. The dCBT-I apps were effectively assisting the users, and the type of interactions promoted engagement. The apps' features were based on design principles from interactive product design, experience design, online social media, and serious gaming. This study contributes to the field by providing a critical summary of the existing dCBT-I apps that could guide future developers in the field to achieve a high engagement.


Assuntos
Terapia Cognitivo-Comportamental , Distúrbios do Início e da Manutenção do Sono , Testes Diagnósticos de Rotina , Humanos , Distúrbios do Início e da Manutenção do Sono/terapia , Software , Resultado do Tratamento
8.
Artigo em Inglês | MEDLINE | ID: mdl-33852402

RESUMO

This article addresses the simultaneous state and unknown input estimation problem for a class of discrete time-varying complex networks (CNs) under redundant channels and dynamic event-triggered mechanisms (ETMs). The redundant channels, modeled by an array of mutually independent Bernoulli distributed stochastic variables, are exploited to enhance transmission reliability. For energy-saving purposes, a dynamic event-triggered transmission scheme is enforced to ensure that every sensor node sends its measurement to the corresponding estimator only when a certain condition holds. The primary objective of the investigation carried out is to construct a recursive estimator for both the state and the unknown input such that certain upper bounds on the estimation error covariances are first guaranteed and then minimized at each time instant in the presence of dynamic event-triggered strategies and redundant channels. By solving two series of recursive difference equations, the desired estimator gains are computed. Finally, an illustrative example is presented to show the usefulness of the developed estimator design method.

9.
Trials ; 22(1): 265, 2021 Apr 09.
Artigo em Inglês | MEDLINE | ID: mdl-33836807

RESUMO

BACKGROUND: Statistics show that every year, 5.4 million people in the world suffer a stroke. Post-stroke cognitive impairment (PSCI) is one of the most common complications after stroke with a rate of 75%, which leads to decreased functions for independent living and reduced quality of life (QOL). Exercise training has been reported to be useful to improve the cognitive functions of post-stroke patients. Yijinjing, a traditional Chinese Qigong exercise characterized by an integration of mind and body in moderate exercise intensity, can improve cognitive functions of PSCI patients. This study aims to explore the feasibility and effectiveness of the Yijinjing exercise in this regard. METHODS: A single-blind, superiority, randomized controlled trial will be employed with evaluations at 3 and 6 months. Seventy-two PSCI patients will be recruited and randomly assigned to the Yijinjing exercise intervention group or the control group (1:1). Participants in the control group will receive routine rehabilitation therapies, including occupational therapy, physical therapy, acupuncture therapy, and health education 5 times a week for 3 months. The intervention group will receive a 12-week routine rehabilitation therapy combined with the Yijinjing exercise intervention for 40 min each session and 3 sessions a week. The primary outcome of cognition will be measured by the Montreal Cognitive Assessment scale (MoCA). Secondary outcomes include executive function, memory function, visuospatial function, sleep quality, gait and motor function, activity of daily living (ADL), and quality of life (QOL). DISCUSSION: Current evidence has reported the effectiveness of traditional Chinese exercise in improving the post-stroke population's motor functions. This research is a randomized controlled trial that evaluates traditional Chinese exercise's effectiveness for PSCI patients. It is expected to expand the traditional Chinese exercise scope and provide a new treatment approach for stroke populations with cognitive impairments. TRIAL REGISTRATION: Chinese Clinical Trial Registry ChiCTR1900026532 . Registered on 13 October 2019.

10.
Shock ; 2021 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-33900712

RESUMO

BACKGROUND: Angiopoietin-like 4 (ANGPTL4) is a secreted glycoprotein that plays an important role in endothelial injury and the inflammatory response. Experimental models have implicated ANGPTL4 in acute respiratory distress syndrome (ARDS), but its impact on the progression of ARDS is unclear. METHODS: Paired bronchoalveolar lavage fluid (BALF) and serum samples were obtained from patients with ARDS (n = 56) within 24 h of diagnosis and from control subjects (n = 32). ANGPTL4, angiopoietin-2, interleukin (IL)-6 and tumor necrosis factor (TNF)-α levels were measured by magnetic Luminex assay. BALF albumin (BA) and serum albumin (SA) were evaluated by enzyme-linked immunosorbent assay. RESULTS: BALF and serum ANGPTL4 concentrations were higher in patients with ARDS than in controls and were even higher in survivors than in non-survivors. The serum ANGPTL4 level was higher in indirect (extrapulmonary) ARDS than in direct (pulmonary) ARDS. Furthermore, BALF and serum ANGPTL4 levels correlated well with angiopoietin-2, IL-6, and TNF-α levels in BALF and serum. BALF ANGPTL4 was positively correlated with the BA/SA ratio (an indicator of pulmonary vascular permeability), and serum ANGPTL4 was associated with the severity of multiple organ dysfunction syndrome based on SOFA and APACHE II scores. Moreover, serum ANGPTL4 was better able to predict 28-day ARDS-related mortality (AUC 0.746, p < 0.01) than the APACHE II score or PaO2/FiO2 ratio. Serum ANGPTL4 was identified as an independent risk factor for mortality in a univariate Cox regression model (p < 0.001). CONCLUSION: ANGPTL4 levels were elevated in patients with ARDS and significantly correlated with disease severity and mortality. ANGPTL4 may be a novel prognostic biomarker in ARDS.

11.
Nano Lett ; 2021 Apr 29.
Artigo em Inglês | MEDLINE | ID: mdl-33913720

RESUMO

Direct CH4 photoconversion into liquid oxygenates under mild conditions still represents a huge challenge. Herein, two-dimensional oxide semiconductors are designed to generate abundant active O- species for activating C-H bond of methane. Taking the synthetic ZnO nanosheets as an example, in situ electron paramagnetic resonance spectra verified their lattice oxygen atoms could capture photoexcited holes and generate active O- species, which could efficiently abstract H from CH4 to generate ·CH3 radicals. Gibbs free energy calculations and in situ Fourier-transform infrared spectroscopy corroborated the rate-limiting step was the first C-H bond activation process, whereas the exoergic oxidation of *CHO to HCOOH was easier than the endoergic overoxidation to CO, accounting for the selective production of liquid oxygenates. As a result, the formation rate of liquid oxygenates over ZnO nanosheets reached 2.21 mmol g-1 h-1 with a selectivity of 90.7% at atmospheric pressure and approximately 50 °C, outperforming previously reported photocatalysts under similar conditions.

12.
ACS Appl Mater Interfaces ; 13(16): 18604-18618, 2021 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-33856200

RESUMO

Microfluctuations in a pH gradient create a harsh microenvironment in tumors, leaving behind the most aggressive, invasive, and drug-resistant tumor cells. Directly visualizing the spatiotemporal distribution of pH variations and accurately quantifying the dynamic acid-base changes during cancer treatment are critical to estimate prognosis and to evaluate therapeutic efficacy. However, the quantification of subtle pH variations dynamically and noninvasively remains challenging. The purpose of this study is to determine and visualize dynamic acid-base changes in solid tumors during anti-acid treatments by magnetic resonance imaging (MRI) using pH-sensitive nanoparticles. We report the development of pH-sensitive nanoparticles, MnO2@BSA, that rapidly and strongly amplify the MR contrast signal in response to the extracellular acidic environment of solid tumors. The spatiotemporal distribution and dynamic fluctuations of pH heterogeneity in NCI-H460 lung tumors were observed with MnO2@BSA at different time points after an anti-acid treatment with esomeprazole, which directly interferes with the acidic microenvironment of the tumor. Imaging results were validated using a pH microsensor. MRI of pH-sensitive MnO2@BSA nanoparticles provided direct readouts of the kinetics of pH gradient fluctuations during esomeprazole treatment. A significant MR signal reduction was observed at the 48 h time point after treatment. The manipulated extracellular pH changes detected noninvasively by MRI coincided with the extracellular pH fluctuations measured with a pH microsensor (pH 6.12-6.63). Immunofluorescence and Western blot analyses confirmed the expression of V-ATPase in NCI-H460 lung cancer cells, which could be inhibited by esomeprazole, as detected by ELISA assay. Overall, these results demonstrate that MnO2@BSA MRI has great potential as a noninvasive tool to accurately monitor pH fluctuations, thereby paving the way for the dynamic detection of acidic microenvironments in vivo without the need for pH microsensors.

13.
Artigo em Inglês | MEDLINE | ID: mdl-33793060

RESUMO

We report the development of a highly sensitive ratiometric fluorescent lateral flow immunoassay (RFLFIA) strip for rapid and accurate detection of acute myocardial infarction biomarker, namely heart-type fatty acid binding protein (H-FABP). The RFLFIA strip works in terms of ratiometric change of fluorescence signal, arising from blending of fluorescence emitted by two composite nanostructures conjugated to capture and probe antibodies and inner filter effect of gold nanoparticles. In conjunction with using custom smartphone-based analytical device and tonality analysis, quantitative detection of H-FABP was achieved with a low limit of detection at 0.21 ng mL-1 . The RFLFIA strip can generate a visually distinguishable green-to-red color change around the threshold concentration of H-FABP (6.2 ng mL-1 ), thus allowing the semi-quantitative diagnosis by the naked eye.

14.
J Phys Chem Lett ; : 3733-3739, 2021 Apr 12.
Artigo em Inglês | MEDLINE | ID: mdl-33843217

RESUMO

Realization of the Kagome antiferromagnetic (KAF) lattice is of high interest because the geometric frustration in the Kagome lattice is expected to give rise to highly degenerated ground states that may host exotic phases such as quantum spin liquid. Here we demonstrate the design and synthesis of a single-layer two-dimensional metal-organic framework (2D-MOF) containing a Kagome lattice of Fe(II) ions assembled on a Au(111) surface. First-principles calculations reveal that the Fe(II) ions are at a high spin state of S = 2 and are coupled antiferromagnetically with nearest-neighboring exchange J1 = 5.8 meV. The ground state comprises various degenerated spin configurations including the well-known q = 0 and q = √3 × âˆš3 phases. Remarkably, we observe a spin excitation at 6 meV using tunneling spectroscopy. This work points out a feasible route toward realizing spin 1/2 KAF, a candidate quantum spin liquid system, by replacing Fe(II) by Cu(II) in the same structure.

15.
J Dig Dis ; 2021 Apr 12.
Artigo em Inglês | MEDLINE | ID: mdl-33844454

RESUMO

OBJECTIVE: Acute pancreatitis (AP) is a common digestive tract disease caused by gall stone obstruction, alcoholism and other factors. Pancreatitis may develop into severe pancreatitis, which has a relatively high mortality rate. Thus, effective methods for treating it need to be developed. Our study tried to assess the protective effect of Se@SiO2 nanospheres on AP. METHODS: Cerulein injection was used to induce acute pancreatitis. C57bl/6 mice were pretreated with Se@SiO2 nanocomposites at 1 and 2 mg/kg. Plasma amylase and lipase, inflammatory cytokines, alanine aminotransferase (ALT), aspartate aminotransferase (AST), blood urea nitrogen (BUN), and Sr were evaluated for each group. Immunofluorescence assay of reactive oxygen species (ROS), myeloperoxidase (MPO), and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling was conducted, and levels of MPO, MDA, SOD, GSH were evaluated. Finally, Western blot analysis was used to evaluate the effects of Se@SiO2 nanoparticle on the protein levels of Nrf2, HO-1, and NQO1 protein as well as TLR4, Myd88, and P-P65 protein in pancreatic tissues. RESULTS: Se@SiO2 nanocomposites alleviated the pathological damage to the pancreas as well as lungs during pancreatitis. Se@SiO2 nanocomposites evidently affected the reduction of pancreatic enzymes and inflammatory cytokines (IL-6, IL-1ß, TNF-α). Se@SiO2 nanocomposites also can reduce other organs injury such as the liver and kidneys (as indicated by lower ALT, AST, BUN, and Sr levels). Moreover, Se@SiO2 nanocomposites reduced oxidative stress. Se@SiO2 nanocomposites ultimately inhibited TLR4/ Myd88/p-p65 pathway and increased the level of NQO1, Nrf2, and HO-1 protein. CONCLUSION: In conclusion, Se@SiO2 nanocomposites exerted a protective effect on acute pancreatitis.

16.
Med Hypotheses ; 149: 110548, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33690002

RESUMO

Diabetic foot ulcer (DFU) has become a major medical, social and economic concern worldwide. It is highly desirable to develop promising new solutions to effectively and appropriately treat DFU. In recent years, investigators have used an innovative technology called proximal tibial cortex transverse distraction (PTCTD) to treat DFU and have achieved satisfactory results in terms of improved wound healing and circumvention of amputation as a consequence of enhanced neovascularization and perfusion of the ulcerated feet after the operation, but the underlying mechanism has not been explored. Previous studies have suggested that in addition to stimulating osteogenesis, bone distraction also facilitates neovascularization, which may be associated with the chemokine stromal cell-derived factor-1 (SDF-1). As an important member of the chemokine family, SDF-1 is primarily responsible for the homing and migration of endothelial progenitor cells (EPCs) or bone marrow-derived mesenchymal stem cells (BMSCs), and plays a central role in the process of neovascularization. In vivo or in vitro experiments show that bone distraction can induce the expression of SDF-1 and increase its plasma concentration. Moreover, some researchers have found that an insufficient level of SDF-1 in the circulation and wounds of patients with DFU can lead to impaired neovascularization. Therefore, we believe that SDF-1 plays an important role in promoting neovascularization of DFU as a result of bone distraction. We summarize the currently relevant literature to put forward an undisclosed but meaningful mechanism of bone distraction in the treatment of DFU.

17.
Artigo em Inglês | MEDLINE | ID: mdl-33786954

RESUMO

Surface vacancies can exert positive impact on CO2 photoreduction activity, yet difficultly maintaining long-term stability. Herein, we first design a fast low-pressure ultraviolet light irradiation strategy for easily regenerating the nearly equivalent surface vacancies, thus concurrently optimizing CO2 photoreduction activity and stability. Taking the defective Bi2O2CO3 nanosheets as an example, nearly equal amount of oxygen vacancies can be regenerated under UV light irradiation. Synchrotron-radiation quasi in-situ X-ray photoelectron spectra disclose the Bi sites in the O-defective Bi2O2CO3 nanosheets can act as the highly active sites, which not only help to activate CO2 molecules, but also contribute to stabilizing the rate-limiting COOH* intermediate. Also, in-situ Fourier transform infrared spectroscopy and in-situ mass spectrometry unravel the UV light irradiation contributes to accelerating CO desorption process. As a result, the O-defective Bi2O2CO3 nanosheets achieve a stability up to 2640 h over 110 cycling tests and a high evolution rate of 275 µmol g-1 h-1 for visible-light-driven CO2 reduction to CO. This study offers a new way for developing sustainable CO2 reduction photocatalysts.

18.
Nano Lett ; 2021 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-33646780

RESUMO

Selective CO2 photoreduction into a high-energy-density C2 product is still challenging. Here, charge-polarized metal pair sites are designed to trigger C-C coupling through manipulating asymmetric charge distribution on the reduction intermediates. Taking the synthetic partially reduced Co3O4 nanosheets as an example, theoretical calculations unveil the asymmetric charge distribution on surface cobalt sites. The formed charge-polarized cobalt pair sites not only donate electrons to CO2 molecules but also accelerate the coupling of asymmetric COOH* intermediates through lowering the energy barrier from 0.680 to 0.240 eV, affirmed by quasi in situ X-ray photoelectron spectroscopy and Gibbs free energy calculations. Also, the electron-rich cobalt sites strengthen their interaction with O of the HOOC-CH2O* intermediate, which favors the C-O bond cleavage and hence facilitates the rate-limiting CH3COOH desorption process. The partially reduced Co3O4 nanosheets achieve 92.5% selectivity of CH3COOH in simulated air, while the CO2-to-CH3COOH conversion ratio is 2.75%, obviously higher than that in pure CO2.

19.
ACS Biomater Sci Eng ; 7(4): 1703-1712, 2021 04 12.
Artigo em Inglês | MEDLINE | ID: mdl-33667076

RESUMO

Biofilms are widely involved in human lives, such as in medical infection, environmental remediation, and industrial processes. However, the control of the biofilm has still been a challenge because of its strong drug resistance. Here, we designed and synthesized an amphipathic antimicrobial peptide (Ac-DKDHDHDQDKDLDVDFDFDADK-NH2 (KKd-11)) that was composed of d-amino acids (DAAs). KKd-11 was found to self-assemble into a hydrogel with an improved long-term antimicrobial ability and a better antiprotease activity as compared to the hydrogel formed by Ac-LKLHLHLQLKLLLVLFLFLALK-NH2 (KK-11). Our results indicated that KKd-11 was not only able to inhibit the formation of biofilms but also could effectively damage preformed mature biofilms and kill the bacteria within the biofilms. Besides, cell viability assays indicated that the KKd-11 peptide had very good biocompatibility. We think d-peptide hydrogels may have great potential in the treatment of biofilm-induced infections.

20.
Artigo em Inglês | MEDLINE | ID: mdl-33709509

RESUMO

Strong metal-support interactions (SMSI) is an important concept in heterogeneous catalysis. Herein, we demonstrate that the Au-TiO2 SMSI of Au/TiO2 catalysts sensitively depends on both Au nanoparticle (NP) sizes and TiO2 facets. Au NPs of ca. 5 nm are more facile undergo Au-TiO2 SMSI than those of ca. 2 nm, while TiO2 {001} and {100} facets are more facile than TiO2 {101} facets. The resulting capsulating TiO2-x overlayers on Au NPs exhibit an average oxidation state between +3 and +4 and a Au-to-TiO2-x charge transfer, which, combined with calculations, determines the Ti:O ratio as ca. 6:11. Both TiO2-x overlayers and TiO2-x -Au interface exhibit easier lattice oxygen activation and higher intrinsic activity in catalyzing low-temperature CO oxidation than the starting Au-TiO2 interface. These results advance fundamental understanding of SMSI and demonstrate engineering of metal NP size and oxide facet as an effective strategy to tune the SMSI for efficient catalysis.

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