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过滤筛选
- 2018
- energy distribution
- graphene edge
- vacuum transistor
- Field emission
- Optoelectronic Information Science and Engineering
- Naval Research Laboratory
- KeyW Corporation
- Pohang University of Science and Technology (POSTECH)
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Two-step synthesis of reduced graphene oxide with columnar-shaped ZnO composites and their photocatalytic performance with natural dye
摘要： Composites of ZnO with reduced graphene oxide were prepared in two-step synthesis process with constant temperature in variation with pH values. The synthesized composites were characterized and the results suggest that ZnO structure in the composites has a columnar morphology with an average diameter ranging 0.8–1.57 μm. The obtained properties of the composites with the present method confirmed that the material morphology influences the absorption and photocatalytic activity of natural dye under sunlight irradiation. The result shows that the maximum degradation efficiency is 64.40% achieved in 120 min.
关键词： Zinc oxide,Columnar morphology,Photocatalytic activity,Reduced graphene oxide,Natural dye
更新于2025-09-23 15:23:52
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Low-damage nitrogen incorporation in graphene films by nitrogen plasma treatment: Effect of airborne contaminants
摘要： Graphene films grown on copper by chemical vapor deposition were exposed to the late afterglow of a reduced-pressure N2 plasma sustained by microwave electromagnetic fields. X-ray photoelectron and Raman spectroscopies reveal extremely high incorporation of plasma-generated N atoms into the graphene film (N/C = 29%) while maintaining an unprecedentedly low-damage generation (D:G = 0.35-0.45) compared to the literature (0.5 to 2.5). The incorporation dynamics between graphene on copper and graphene on copper oxide are also compared and discussed. After transfer on SiO2/Si substrate, the N/C content decrease to only 6%. This reveals that a large part of the N atoms are weakly bonded to the graphene surface. Most of the nitrogen incorporation seems linked to the functionalization of weakly bonded hydrocarbons initially adsorbed from air exposure or carbon-nitrogen structures arising from plasma-surface interactions.
关键词： X-Ray photoelectron spectroscopy,Raman spectroscopy,graphene,downstream plasma treatment,N-incorporation
更新于2025-09-23 15:23:52
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Construction of a Biosensor Based on a Combination of Cytochrome c, Graphene, and Gold Nanoparticles
摘要： A biosensor based on a combination of cytochrome c (Cyt c), electrochemical reduced graphene oxides (ERGO), and gold nanoparticles (AuNPs) on a glassy carbon electrode (GCE) was fabricated. The proposed biosensor electrode was denoted as GCE/ERGO-Na?on/AuNPs/Cyt c/Na?on, where ERGO-Na?on was deposited by dropping graphene oxides-Na?on mixed droplet ?rst and following electrochemical reduction, AuNPs were directly deposited on the surface of the ERGO-Na?on modi?ed electrode by electrochemical reduction, and other components were deposited by the dropping-dry method. The effect of the deposition amount of AuNPs on direct electrochemistry of Cyt c in the proposed electrode was investigated. The hydrogen peroxide was taken to evaluate the performance of the proposed biosensor. The results showed that the biosensor has great analytical performance, including a high sensitivity, a wide linear range, a low detection limit, and good stability, reproducibility, and reliability.
关键词： gold nanoparticles,cytochrome c,graphene,direct electrochemistry,biosensor,hydrogen peroxide
更新于2025-09-23 15:23:52
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3D graphene/AgBr/Ag cascade aerogel for efficient photocatalytic disinfection
摘要： To design semiconductor-based photocatalysts with efficient charge carriers separation and transfer remains an enduring goal of artificial photosynthesis toward target redox reactions. Herein, we report a cascade monolith composite of ternary reduced graphene oxide aerogel/silver bromide/silver (RGA/AgBr/Ag) with efficient charge carriers separation, which exhibits much higher activity than bare AgBr toward photocatalytic bacteria inactivation. Mechanistic studies reveal that the reduced graphene oxide aerogel (RGA) scaffold and Ag nanoparticles serve as electron relay mediators to promote the charge carriers separation and transfer. In addition, the metallic Ag nanoparticles derived from the photoreduction of AgBr during the photocatalytic disinfection can further boost the separation of charge carriers. Control experiments demonstrate that the surface plasmon resonance (SPR)-excited hot electrons of Ag nanoparticles also contributes to enhancing the photoactivity of RGA/AgBr/Ag. As such, the synergy of multiple electron transfer behavior integratively leads to the boosted photocatalytic performance of such RGA/AgBr/Ag aerogel for bacteria inactivation with convenient recyclable operability.
关键词： charge transfer,aerogel,silver bromide,Ag nanoparticles,reduced graphene oxide
更新于2025-09-23 15:23:52
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PEGylated doxorubicin cloaked nano-graphene oxide for dual-responsive photochemical therapy
摘要： Graphene oxide (GO) own huge surface area and high drug loading capacity for aromatic molecules, such as doxorubicin (DOX). However, its biocompatibility is poor and it might agglomerate in physiological condition. Chemical modification of GO with hydrophilic polymer, especially PEGylation, was a common method to improve its biocompatibility. But the chemical modification of GO was complicated, and its drug loading capacity might be reduced because of the occupation of its functional groups. In this study, DOX-PEG polymers with different PEG molecular weight were synthesized to modify nano graphene oxide (NGO) to simultaneously realize the solubilization of NGO and the high loading capacity of DOX. The result showed that the drug release of NGO@DOX-PEG was pH sensitive. NIR irradiation could augment the drug release, cellular uptake, cytotoxicity and nuclear translocation of nanodrugs. Among the three kinds of nanodrugs, NGO@DOX-PEG5K was superior to others. It suggested that after conjugating with PEG, the bond between DOX-PEG and NGO was weakened, which resulted in a better drug release and treatment effect. In summary, the NIR and pH dual-responsive NGO@DOX-PEG nanodrugs were developed by noncovalent modification, and it demonstrated excellent biocompatibility and photochemical therapeutic effect, presenting a promising candidate for antitumor therapy, especially NGO@DOX-PEG5K.
关键词： Nano-drug Delivery System,pH sensitive,Nano-Graphene Oxide,photochemical therapy,Doxorubicin
更新于2025-09-23 15:23:52
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Growth of graphene on SiO2 with hexagonal boron nitride buffer layer
摘要： One-through process of graphene growth on insulator substrates with inserting a hexagonal boron nitride (h-BN) buffer layer is expected to yield significant improvements in performance of electron transport properties of graphene devices due to the alleviation of the interface interaction between graphene and insulators and the enhancement of the flatness of the substrate. In this study, we successfully fabricated a graphene/h-BN/SiO2 heterostructure by direct chemical vapor deposition (CVD) without mechanical transfer processes. It was found that h-BN promotes the growth of graphene on SiO2 whereas the graphene growth without the h-BN layer is extremely difficult. The electronic structures of graphene and h-BN were investigated by using micro-Raman spectroscopy and near edge X-ray absorption fine structure (NEXAFS) spectroscopy. The B and N K-edge NEXAFS revealed that substitutional oxygen impurities with the chemical form of BN3?xOx (x = 1, 2, 3) are present in both h-BN/SiO2 and graphene/h-BN/SiO2. The number of O substitutional impurities is two times larger in graphene/h-BN/SiO2 than in h-BN/SiO2, which is presumed to be due to the reaction with oxygen from SiO2 and methanol during the graphene growth. The interfacial interaction between graphene and h-BN was found to be weak in graphene/h-BN/SiO2. The present study shows that the h-BN layer grown with CVD can be a superior buffer layer for graphene devices which enables direct graphene growth on it and to decrease the interactions with insulator substrates.
关键词： NEXAFS,h-BN,Chemical vapor deposition,Buffer layer,Graphene
更新于2025-09-23 15:23:52
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Phononic Casimir corrections for Graphene resonator
摘要： By calculating a Casimir energy for the acoustic phonons of Graphene, we find some temperature-dependent corrections for the pretension of a Graphene sheet suspended on a trench. We obtain values of the order of few mN/m for these corrections in fully as well as doubly clamped Graphene on a narrow trench with one nanometer width, at room temperature. These values are considerable compared to the experimental values, and can increase the fundamental resonance frequency of the Graphene. The values of these corrections increase by increasing the temperature, and so they can be utilized for tuning the Graphene pretension.
关键词： Resonance frequency,Graphene sheet,Casimir energy,Acoustic phonons,Pretension,Nanoelectromechanical systems
更新于2025-09-23 15:23:52
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Chemical vapor deposition of graphene on refractory metals: The attempt of growth at much higher temperature
摘要： Large area graphene is usually grown by chemical vapor deposition on Cu or Ni catalysts at ～1000 °C. For most materials, high temperature leads to high quality. However, graphene growth at even higher temperatures is rarely reported. Therefore, here we systematically investigate the graphene deposition on refractory metals i.e. metals with extremely high melting points. The growth parameters and material characterizations are given in detail. On Ta which readily forms carbides during the carbon deposition, the growth mode is monolayer due to the chemical absorption of excess carbon in the bulk metal. On Re, there is no carbide formed (except in extreme conditions), which greatly simpli?es the scenario. Because of the relatively high carbon solubility in Re, the growth temperature has to be limited in order not to drift into the dominantly multilayer graphene regime caused by the carbon segregation. Graphene with reasonable quality has been achieved, although not as good as expected. For example, on Ta, the residual bonds between the graphene and substrate deteriorate the graphene crystalline quality. Despite the di?culties in refractory metal etching, the transfer technique of the graphene is also explored. This research contributes to the fundamental understanding of the graphene growth theory and technology on refractory metals.
关键词： Refractory metal,Graphene,Chemical vapor deposition,High temperature growth
更新于2025-09-23 15:23:52
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Characterization of M1 and M2 polarization phenotypes in peritoneal macrophages after treatment with graphene oxide nanosheets
摘要： Macrophages play a key role in nanoparticle removal and are primarily responsible for their uptake and trafficking in vivo. Due to their functional plasticity, macrophages display a spectrum of phenotypes between two extremes identified as pro-inflammatory M1 and reparative M2 macrophages, characterized by the expression of specific cell surface markers and the secretion of different cytokines. The influence of graphene oxide (GO) nanosheets functionalized with poly(ethylene glycol-amine) and labelled with fluorescein isothiocyanate (FITC-PEG-GO) on polarization of murine peritoneal macrophages towards M1 and M2 phenotypes was evaluated in basal and stimulated conditions by flow cytometry and confocal microscopy through the expression of different cell markers: CD80 and iNOS as M1 markers, and CD206 and CD163 as M2 markers. Although FITC-PEG-GO did not induce M1 or M2 macrophage polarization after 24 and 48 h in basal conditions, this nanomaterial decreased the percentage of M2 reparative macrophages. We have also compared control macrophages with macrophages that have or have not taken up FITC-PEG-GO after treatment with these nanosheets (GO+ and GO- cells, respectively). The CD80 expression diminished in GO+ macrophages after 48 h of GO treatment but the CD206 expression in GO+ population showed higher values than in both GO- population and control macrophages. In the presence of pro-inflammatory stimuli (LPS and IFN-γ), a significant decrease of CD80+ cells was observed after treatment with GO. This nanomaterial also induced significant decreases of CD206+ and CD163+ cells in the presence of reparative stimulus (IL-4). The CD80, iNOS and CD206 expression was lower in both GO- and GO+ cells than in control macrophages. However, higher CD163 expression was obtained in both GO- and GO+ cells in comparison with control macrophages. All these facts suggest that FITC-PEG-GO uptake did not induce the macrophage polarization towards the M1 pro-inflammatory phenotype, promoting the control of the M1/M2 balance with a slight shift towards M2 reparative phenotype involved in tissue repair, ensuring an appropriate immune response to these nanosheets.
关键词： Graphene oxide nanosheets,Macrophage polarization,Peritoneal macrophages,Cytokine profiling
更新于2025-09-23 15:23:52
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Nanoscale reduced graphene oxide-mediated photothermal therapy together with IDO inhibition and PD-L1 blockade synergistically promote antitumor immunity
摘要： Despite the potential efficacy of immune checkpoint blockade for effective treatment of cancer, this therapeutic modality is not generally curative and only a fraction of patients respond. Combination approaches provide strategies to target multiple antitumor immune pathways to induce synergistic antitumor immunity. Here, a multi-combination immunotherapy including photothermal therapy (PTT), indoleamine-2,3-dioxygenase (IDO) inhibition and programmed cell death-ligand 1 (PD-L1) blockade is introduced for inducing synergistic antitumor immunity. We designed a multifunctional IDO inhibitor (IDOi)-loaded reduced graphene oxide (rGO)-based nanosheets (IDOi/rGO nanosheets) with the properties to directly kill tumor cells under laser irradiation and in situ trigger antitumor immune response. In vivo experiments further revealed that the triggered immune response can be synergistically promoted by IDO inhibition and PD-L1 blockade; the responses included the enhancement of tumor-infiltrating lymphocytes (TILs) including CD45+ leukocytes, CD4+ T cells, CD8+ T cells and NK cells, the inhibition of the immune suppression activity of regulator T cells (Tregs) and the production of INF-γ. We also demonstrate that the three combinations of PTT, IDO inhibition and PD-L1 blockade could effectively inhibit the growth of both irradiated tumors and tumors in distant sites without PTT treatment. This work can be thought as an important proof-of-concept to target multiple antitumor immune pathways to induce synergistic antitumor immunity.
关键词： photothermal therapy,reduced graphene oxide,IDO inhibition,combinatorial immunotherapy,PD-L1
更新于2025-09-23 15:23:52