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1.
Anal Chim Acta ; 1191: 339281, 2022 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-35033247

RESUMO

Immunotherapy has emerged as an effective treatment modality for cancer. The interaction of programmed cell death ligand-1 (PD-L1) and programmed cell death protein-1 (PD-1) plays a key role in tumor-related immune escape and has become one of the most extensive targets for immunotherapy. Herein, we investigated the interaction of PD-L1 with its antibody and PD-1 using atomic force microscopy-based single molecule force spectroscopy for the first time. It was found that the PD-L1/anti-PD-L1 antibody complex was easier to dissociate than PD-L1/PD-1. The unbinding forces of specific interaction of PD-L1 on T24 cells with its antibody and PD-1 were quantitatively measured and similar to those on substrate. In addition, the location of PD-L1 on T24 cells was mapped at the single-molecule level by force-volume mapping. The force maps revealed that PD-L1 randomly distributed on T24 cells surface. The recognition events on cells obviously increased after INF-γ treatment, which proved that INF-γ up-regulated the expression of PD-L1 on T24 cells. These findings enrich our understanding of the molecular mechanisms by which PD-L1 interacts with its antibody and PD-1. It provides useful information for the physical factors that is needed to be considered in the design of inhibitors for tumor immunology.


Assuntos
Antígeno B7-H1 , Neoplasias , Humanos , Imunoterapia , Microscopia de Força Atômica
2.
Adv Mater ; : e2108947, 2022 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-34994990

RESUMO

High-nickel (Ni≥90%) cathodes with high specific capacity hold great potential for next-generation lithium-ion batteries (LIBs). However, their practical application is restricted by the high interfacial reactivity under continuous air erosion and electrolyte assaults. Herein, a stable high-nickel cathode was rationally designed via in-situ induction of a dense amorphous Li2 CO3 on the particle surface by a preemptive atmosphere control. Among the residual lithium compounds, Li2 CO3 is the most thermodynamically stable one so that the dense Li2 CO3 coating layer can serve as a physical protection layer to isolate the cathodes from contact with moist air. Furthermore, amorphous Li2 CO3 can be transformed into a robust F-rich cathode electrolyte interphase (CEI) during cycling, which reinforces the cathodes interfacial stability and improves electrochemical performance. The assembled coin cell with this modified cathode delivers a high discharge capacity of 232.4 mAh g-1 with a superior initial coulombic efficiency of 95.1%, and a considerable capacity retention of 90.4% after 100 cycles. Furthermore, no slurry gelation occurred during large-scale electrode fabrication process. This work opens a valuable perspective on the evolution of amorphous Li2 CO3 in LIBs and provides guidance on protecting unstable high-capacity cathodes for energy storage devices. This article is protected by copyright. All rights reserved.

4.
J Mater Chem B ; 9(44): 9204-9212, 2021 Nov 17.
Artigo em Inglês | MEDLINE | ID: mdl-34698747

RESUMO

Studying the influence of nanomaterials on the microstructure and mechanical properties of cells is essential to guide the biological applications of nanomaterials. In this article, the effects of the first synthesized PDA@CeO2 nanoparticles (NPs) with multiple ROS scavenging activities on cell ultra-morphology and mechanical properties were investigated by atomic force microscopy (AFM). After the cells were exposed to PDA@CeO2 NPs, there was no obvious change in cell morphology, but the Young's modulus of the cells was increased. On the contrary, after the cells were damaged by H2O2, the secreted molecules appeared on the cell surface, and the Young's modulus was decreased significantly. However, PDA@CeO2 NPs could effectively inhibit the reduction of the Young's modulus caused by oxidative stress damage. PDA@CeO2 NPs could also protect F-actin from oxidative stress damage and maintain the stability of the cytoskeleton. This work investigates the intracellular antioxidant mechanism of nanomaterials from the changes in the microstructure and biomechanics of living cells, providing a new analytical approach to explore the biological effects of nanomaterials.

5.
Natl Sci Rev ; 8(2): nwaa150, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34691570

RESUMO

The dendrite growth of Li anodes severely degrades the performance of lithium-oxygen (Li-O2) batteries. Recently, hybrid solid electrolyte (HSE) has been regarded as one of the most promising routes to tackle this problem. However, before this is realized, the HSE needs to simultaneously satisfy contradictory requirements of high modulus and even, flexible contact with Li anode, while ensuring uniform Li+ distribution. To tackle this complex dilemma, here, an HSE with rigid Li1.5Al0.5Ge1.5(PO4)3 (LAGP) core@ultrathin flexible poly (vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) shell interface has been developed. The introduced large amount of nanometer-sized LAGP cores can not only act as structural enhancer to achieve high Young's modulus but can also construct Li+ diffusion network to homogenize Li+ distribution. The ultrathin flexible PVDF-HFP shell provides soft and stable contact between the rigid core and Li metal without affecting the Li+ distribution, meanwhile suppressing the reduction of LAGP induced by direct contact with Li metal. Thanks to these advantages, this ingenious HSE with ultra-high Young's modulus of 25 GPa endows dendrite-free Li deposition even at a deposition capacity of 23.6 mAh. Moreover, with the successful inhibition of Li dendrites, the HSE-based quasi-solid-state Li-O2 battery delivers a long cycling stability of 146 cycles, which is more than three times that of gel polymer electrolyte-based Li-O2 battery. This new insight may serve as a starting point for further designing of HSE in Li-O2 batteries, and can also be extended to various battery systems such as sodium-oxygen batteries.

6.
J Am Chem Soc ; 143(40): 16768-16776, 2021 Oct 13.
Artigo em Inglês | MEDLINE | ID: mdl-34607434

RESUMO

Solid-state Li-metal batteries offer a great opportunity for high-security and high-energy-density energy storage systems. However, redundant interfacial modification layers, intended to lead to an overall satisfactory interfacial stability, dramatically debase the actual energy density. Herein, a dual-interface amorphous cathode electrolyte interphase/solid electrolyte interphase CEI/SEI protection (DACP) strategy is proposed to conquer the main challenges of electrochemical side reactions and Li dendrites in hybrid solid-liquid batteries without sacrificing energy density via LiDFOB and LiBF4 in situ synergistic conversion. The amorphous CEI/SEI products have an ultralow mass proportion and act as a dynamic shield to cooperatively enforce dual electrodes with a well-preserved structure. Thus, this in situ DACP layer subtly reconciles multiple interfacial compatibilities and a high energy density, endowing the hybrid solid-liquid Li-metal battery with a sustainably brilliant cycling stability even at practical conditions, including high cathode loading, high voltage (4.5 V), and high temperature (45 °C) conditions, and enables a high-energy-density (456 Wh kg-1) pouch cell (11.2 Ah, 5 mA h cm-2) with a lean electrolyte (0.92 g Ah-1, containing solid and liquid phases). The compatible modification strategy points out a promising approach for the design of practical interfaces in future solid-state battery systems.

7.
ACS Nano ; 15(10): 16562-16571, 2021 10 26.
Artigo em Inglês | MEDLINE | ID: mdl-34569229

RESUMO

Cryo-electron microscopy (cryo-EM) has emerged as a vital tool to reveal the native structure of beam-sensitive biomolecules and materials. Yet high-resolution cryo-EM analysis is still limited by the poorly controlled specimen preparation and urgently demands a robust supporting film material to prepare desirable samples. Here, we developed a bilayer Janus graphene membrane with the top-layer graphene being functionalized to interact with target molecules on the surface, while the bottom layer being kept intact to reinforce its mechanical steadiness. The ultraclean and atomically thin bilayer Janus membrane prepared by our protocol on one hand generates almost no extra noise and on the other hand reduces the specimen motion during cryo-EM imaging, thus allowing the atomic-resolution characterization of surface functional groups. Using such Janus membranes in cryo-EM specimen preparation, we were able to directly image the lithium dendrite and reconstruct macromolecules at near-atomic resolution. Our results demonstrate the bilayer Janus design as a promising supporting material for high-resolution cryo-EM and EM imaging.


Assuntos
Grafite , Microscopia Crioeletrônica , Substâncias Macromoleculares , Movimento (Física) , Manejo de Espécimes
8.
J Phys Chem Lett ; 12(22): 5279-5285, 2021 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-34061525

RESUMO

The chemisorption of an electrolyte species on electrode surfaces is ubiquitous and affects the dynamics and mechanism of various electrochemical reactions. Understanding of the chemical structure and property of the resulting electrical double layer is vital but limited. Herein, we operando probed the electrochemical interface between a gold electrode surface and a common electrolyte, phosphate buffer, using our newly developed in situ liquid secondary ion mass spectrometry. We surprisingly found that, on the positively charged gold electrode surface, sodium cations were anchored in the Stern layer in a partially dehydrated form by a formation of compact ion pairs with the accumulated phosphate anions. The resulting strong adsorption phase was further revealed to retard the electro-oxidation reaction of ascorbate. This finding addressed one major gap in the fundamental science of electrode-electrolyte interfaces, namely, where and how cations reside in the double layer to impose effects on electrochemical reactions, providing insights into the engineering of better electrochemical systems.

9.
Angew Chem Int Ed Engl ; 60(30): 16388-16393, 2021 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-34018292

RESUMO

Inorganic cesium lead halide perovskites offer a pathway towards thermally stable photovoltaics. However, moisture-induced phase degradation restricts the application of hole transport layers (HTLs) with hygroscopic dopants. Dopant-free HTLs fail to realize efficient photovoltaics due to severe electrical loss. Herein, we developed an electrical loss management strategy by manipulating poly(3-hexylthiophene) with a small molecule, i.e., SMe-TATPyr. The developed P3HT/SMe-TATPyr HTL shows a three-time increase of carrier mobility owing to breaking the long-range ordering of "edge-on" P3HT and inducing the formation of "face-on" clusters, over 50 % decrease of the perovskite surface defect density, and a reduced voltage loss at the perovskite/HTL interface because of favorable energy level alignment. The CsPbI2 Br perovskite solar cell demonstrates a record-high efficiency of 16.93 % for dopant-free HTL, and superior moisture and thermal stability by maintaining 96 % efficiency at low-humidity condition (10-25 % R. H.) for 1500 hours and over 95 % efficiency after annealing at 85 °C for 1000 hours.

10.
Nano Lett ; 20(10): 7469-7475, 2020 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-32881534

RESUMO

The integration of high-k gate dielectrics with two-dimensional (2D) semiconducting channel materials is essential for high-performance and low-power electronics. However, the conformal deposition of a uniform high-k dielectric with sub-1 nm equivalent oxide thickness (EOT) and high interface quality on high-mobility 2D semiconductors is still challenging. Here, we report a facile approach to synthesize a uniform high-k (εr ∼ 22) amorphous native oxide Bi2SeOx on the high-mobility 2D semiconducting Bi2O2Se using O2 plasma at room temperature. The conformal native oxide can directly serve as gate dielectrics with EOT of ∼0.9 nm, while the original properties of underlying 2D Bi2O2Se is preserved. Furthermore, high-resolution area-selective oxidation of Bi2O2Se is achieved to fabricate discrete electronic components. This facile integration of a high-mobility 2D semiconductor and its high-k native oxide holds high promise for next-generation nanoelectronics.

11.
Nano Lett ; 20(9): 6798-6806, 2020 Sep 09.
Artigo em Inglês | MEDLINE | ID: mdl-32787178

RESUMO

Graphene grown on Cu by chemical vapor deposition is rough due to the surface roughening of Cu for releasing interfacial thermal stress and/or graphene bending energy. The roughness degrades the electrical conductance and mechanical strength of graphene. Here, by using vicinal Cu(111) and flat Cu(111) as model substrates, we investigated the critical role of original surface topography on the surface deformation of Cu covered by graphene. We demonstrated that terrace steps on vicinal Cu(111) dominate the formation of step bunches (SBs). Atomically flat graphene with roughness down to 0.2 nm was grown on flat Cu(111) films. When SB-induced ripples were avoided, as-grown ultraflat graphene maintained its flat feature after transfer. The ultraflat graphene exhibited extraordinary mechanical properties with Young's modulus ≈ 940 GPa and strength ≈ 117 GPa, comparable to mechanical exfoliated ones. Molecular dynamics simulation revealed the mechanism of softened elastic response and weakened strength of graphene with rippled structures.

12.
Anal Chim Acta ; 1124: 52-59, 2020 Aug 08.
Artigo em Inglês | MEDLINE | ID: mdl-32534675

RESUMO

MeCP2 is an essential transcriptional repressor that mediates transcriptional inhibition by binding to methylated DNA. The binding specificity of MeCP2 protein to methylated DNA was considered to depend on its methyl-CpG binding domain (MBD). In this study, we used atomic force microscope based single-molecular force spectroscopy to investigate the interaction of MeCP2 MBD and methylated DNA. The specific interaction forces of the MeCP2 MBD-methylated DNA complexes were measured for the first time. The dynamics was also investigated by measuring the unbinding force of the complex at different loading rates. In addition, the distribution of unbinding forces and binding probabilities of MeCP2 MBD and different DNA were studied at the same loading rate. It was found that MeCP2 MBD had weak interaction with hemi-methylated and unmethylated DNA compared to methylated DNA. This work revealed the binding characteristics of MeCP2 MBD and methylated DNA at the single-molecule level. It provides a new idea for exploring the molecular mechanism of MeCP2 in regulating methylation signals.


Assuntos
DNA/química , Proteína 2 de Ligação a Metil-CpG/química , Imagem Individual de Molécula , Metilação de DNA , Estrutura Molecular
13.
Nanoscale ; 12(22): 11927-11935, 2020 Jun 11.
Artigo em Inglês | MEDLINE | ID: mdl-32458960

RESUMO

Heparin, as an effective anticoagulant, has been increasingly used in clinical practice, but the binding characteristics and influence of exogenous heparin on heparin-affinity proteins in the body are still unclear. Vascular endothelial growth factor A (VEGF-A) is a kind of protein with heparin affinity involved in the pathogenesis and progression of many angiogenesis-dependent diseases including cancer. As an important step in the angiogenesis-related cascade, it is necessary to clarify the interaction between VEGF165 (the major form of VEGF-A) and heparin. In this work, we investigated this interaction based on single molecule force spectroscopy (SMFS) and molecular dynamics (MD) simulation. From the SMFS study, binding forces between VEGF165 and heparin at different loading rates were quantified under near-physiological conditions. Meanwhile, the kinetic and thermodynamic parameters of the VEGF165/heparin complex dissociation process were also obtained. Results of MD simulation visually displayed the most likely binding conformation of VEGF165/heparin* complex, indicating that hydrogen bonding and hydrophobic interaction play a positive role in the binding between the two molecules. This work provides a new insight into the binding between VEGF165 and heparin and offers a research framework to study the interaction between heparin and multiple heparin affinity proteins, which is helpful for guiding the safe application of heparin in the clinic.


Assuntos
Heparina , Fator A de Crescimento do Endotélio Vascular , Análise Espectral , Fatores de Crescimento do Endotélio Vascular
14.
ACS Nano ; 14(2): 1656-1664, 2020 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-31961130

RESUMO

Stacking order has a strong influence on the coupling between the two layers of twisted bilayer graphene (BLG), which in turn determines its physical properties. Here, we report the investigation of the interlayer coupling of the epitaxially grown single-crystal 30°-twisted BLG on Cu(111) at the atomic scale. The stacking order and morphology of BLG is controlled by a rationally designed two-step growth process, that is, the thermodynamically controlled nucleation and kinetically controlled growth. The crystal structure of the 30°-twisted bilayer graphene (30°-tBLG) is determined to have quasicrystal-like symmetry. The electronic properties and interlayer coupling of the 30°-tBLG are investigated using scanning tunneling microscopy and spectroscopy. The energy-dependent local density of states with in situ electrostatic doping shows that the electronic states in two graphene layers are decoupled near the Dirac point. A linear dispersion originated from the constituent graphene monolayers is discovered with doubled degeneracy. This study contributes to controlled growth of twist-angle-defined BLG and provides insights on the electronic properties and interlayer coupling in this intriguing system.

15.
ACS Sens ; 4(11): 3034-3041, 2019 11 22.
Artigo em Inglês | MEDLINE | ID: mdl-31642312

RESUMO

A microcantilever array biosensor based on a sandwich structure has been developed for simultaneously measuring two biomarkers carcinoembryonic antigen (CEA) and α-fetoprotein (AFP) via an optical readout technique-real-time monitoring of the profile of cantilever. First, the aptamers of CEA and AFP were self-assembled on their respective cantilevers. After the adsorption of the mixture of CEA and AFP, further specific interaction was performed via the addition of the antibodies specific to each target. The compressive stress on the cantilever was generated by the aptamer-antigen-antibody sandwich structure formed on the gold surface, resulting in cantilever bending. The profile of cantilever could be monitored in real time. The relationship between the deflection value at the 90% position of the cantilever and the target concentration served as a calibration curve, and the detection sensitivity was 1.3 ng/mL for CEA and 0.6 ng/mL for AFP, respectively. This work demonstrated the ability of simultaneously measuring two biomarkers via a microcantilever array biosensor, giving great potential for further application in detecting several targets simultaneously for early clinical diagnosis.


Assuntos
Técnicas Biossensoriais , Antígeno Carcinoembrionário/análise , alfa-Fetoproteínas/análise , Técnicas Biossensoriais/instrumentação , Ouro/química , Humanos , Propriedades de Superfície , Fatores de Tempo
16.
Anal Chim Acta ; 1048: 186-193, 2019 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-30598149

RESUMO

Panax notoginseng saponins (PNS) have shown to be the biologically active constituents responsible for the therapeutic action of panax notoginseng. PNS could help to restrain the oxidative stress, however, whether biomechanical properties of the single cell involve in the protective effect exerted by PNS against oxidative stress injury remains unclear. In this work, we investigated the protective mechanism of PNS against oxidative stress based on the PeakForce Tapping technology firstly, focusing on the biomechanical properties of single human umbilical vascular endothelium cell (HUVEC). PNS display distinct inhibition on the reduction of the young's modulus of cells caused by oxidative stress damage. Combining with immunofluorescence assay, it indicates that improving the stability of cytoskeleton is a significant way for PNS to play a protective role in HUVEC cells during oxidative damage. This work provides a new idea for exploring the functional mechanism of traditional Chinese medicine at the single cell level, and reveals great potential of the atomic force microscope in studying the drug mechanism.


Assuntos
Módulo de Elasticidade/efeitos dos fármacos , Células Endoteliais da Veia Umbilical Humana/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Panax notoginseng/química , Substâncias Protetoras/farmacologia , Saponinas/farmacologia , Citoesqueleto/efeitos dos fármacos , Medicamentos de Ervas Chinesas/farmacologia , Humanos
17.
Talanta ; 191: 461-468, 2019 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-30262086

RESUMO

Epithelial-mesenchymal transition (EMT) is a biological process during which cells lose their characteristic structure and biochemical properties then adopt typical features of a mesenchymal phenotype. Alterations in the morphology, structure, and mechanical properties of cells during EMT are associated with a series of pathological processes. In this work, atomic force microscopy (AFM) is used for investigating effects of TGF-ß1 on morphology and mechanical properties of living bladder cancer cells (T24) during EMT for the first time. High-resolution topography and Young's modulus images of T24 living cell are obtained simultaneously. The results show that TGF-ß1 is able to induce EMT, leading to the increased F-actin stress fibers and much higher Young's modulus values of T24 living cells. It reveals that the cytoskeletal-associated cell architecture is closely related to the mechanical dynamics of T24 cells during EMT. This work provides new insights into the changes of cell morphology and mechanical properties during EMT. It enables us to gain a deeper understanding of the growth, development and metastasis of the bladder cancer cell therefore it is of great significance for studying the pathological mechanism of cells at single-cell level.


Assuntos
Transição Epitelial-Mesenquimal , Fenômenos Mecânicos , Microscopia de Força Atômica , Actinas/metabolismo , Fenômenos Biomecânicos , Linhagem Celular Tumoral , Humanos , Fibras de Estresse/metabolismo , Fator de Crescimento Transformador beta1/metabolismo
18.
Small ; 14(22): e1800725, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29717818

RESUMO

Corrugation is a ubiquitous phenomenon for graphene grown on metal substrates by chemical vapor deposition, which greatly affects the electrical, mechanical, and chemical properties. Recent years have witnessed great progress in controlled growth of large graphene single crystals; however, the issue of surface roughness is far from being addressed. Here, the corrugation at the interface of copper (Cu) and graphene, including Cu step bunches (CuSB) and graphene wrinkles, are investigated and ascribed to the anisotropic strain relaxation. It is found that the corrugation is strongly dependent on Cu crystallographic orientations, specifically, the packed density and anisotropic atomic configuration. Dense Cu step bunches are prone to form on loose packed faces due to the instability of surface dynamics. On an anisotropic Cu crystal surface, Cu step bunches and graphene wrinkles are formed in two perpendicular directions to release the anisotropic interfacial stress, as revealed by morphology imaging and vibrational analysis. Cu(111) is a suitable crystal face for growth of ultraflat graphene with roughness as low as 0.20 nm. It is believed the findings will contribute to clarifying the interplay between graphene and Cu crystal faces, and reducing surface roughness of graphene by engineering the crystallographic orientation of Cu substrates.

19.
Chem Sci ; 9(8): 2098-2104, 2018 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-29675251

RESUMO

Phthalocyanine (Pc) molecules exhibit high extinction coefficients in near-infrared region, rendering them well-suited for phototherapies, but most of their applications are limited to the field of photodynamic therapy (PDT). Herein, for the first time, we illustrate that Pc molecules can be endowed with excellent photothermal properties by means of structural regulation rather than formation of aggregates. Three representative Pc derivatives show efficient activities of photothermal therapy (PTT) against human hepatocellular carcinoma cells. Among them, copper phthalocyanine (PcC1) exhibits a high in vivo PTT efficacy against mice bearing S180 tumors. The unique investigation in this article should light up a perspective of Pc's new applications for PTT, which enable to make up the inherent defects of PDT.

20.
Scanning ; 2017: 2027079, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29109804

RESUMO

Chronic inflammation orchestrates the tumor microenvironment and is strongly associated with cancer. Tumor necrosis factor-α (TNFα) is involved in tumor invasion and metastasis by inducing epithelial to mesenchymal transition (EMT). This process is defined by the loss of epithelial characteristics and gain of mesenchymal traits. The mechanisms of TNFα-induced EMT in cancer cells have been well studied. However, mechanical properties have not yet been probed. In this work, atomic force microscopy (AFM) was applied to investigate the morphology and mechanical properties of EMT in HCT116 human colon cancer cells. A remarkable morphological change from cobblestone shape to spindle-like morphology was observed. In parallel, AFM images showed that the cellular cytoskeleton was rearranged from a cortical to a stress-fiber pattern. Moreover, cell stiffness measurements indicated that Young's modulus of cells gradually reduced from 1 to 3 days with TNFα-treatment, but it has an apparent increase after 4 days of treatment compared with that for 3 days. Additionally, Young's modulus of the cells treated with TNFα for 4 days is slightly larger than that for 1 or 2 days, but still less than that of the untreated cells. Our work contributes to a better understanding of colorectal cancer metastasis induced by inflammation.


Assuntos
Células Epiteliais/citologia , Células Epiteliais/efeitos dos fármacos , Transição Epitelial-Mesenquimal/efeitos dos fármacos , Fator de Necrose Tumoral alfa/metabolismo , Forma Celular/efeitos dos fármacos , Células HCT116 , Humanos , Fenômenos Mecânicos , Microscopia de Força Atômica
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