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Nanowire‐Intensified Metal‐Enhanced Fluorescence in Hybrid Polymer‐Plasmonic Electrospun Filaments
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Andrea Camposeo Radoslaw Jurga Maria Moffa Alberto Portone Francesco Cardarelli Fabio Della Sala Cristian Ciracì Dario Pisignano 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(19)
Hybrid polymer‐plasmonic nanostructures might combine high enhancement of localized fields from metal nanoparticles with light confinement and long‐range transport in subwavelength dielectric structures. Here, the complex behavior of fluorophores coupling to Au nanoparticles within polymer nanowires, which features localized metal‐enhanced fluorescence (MEF) with unique characteristics compared to conventional structures, is reported. The intensification effect when the particle is placed in the organic filaments is remarkably higher with respect to thin films of comparable thickness, thus highlighting a specific, nanowire‐related enhancement of MEF effects. A dependence on the confinement volume in the dielectric nanowire is also indicated, with MEF significantly increasing upon reduction of the wire diameter. These findings are rationalized by finite element simulations, predicting a position‐dependent enhancement of the quantum yield of fluorophores embedded in the fibers. Calculation of the ensemble‐averaged fluorescence enhancement unveils the possibility of strongly enhancing the overall emission intensity for structures with size twice the diameter of the embedded metal particles. These new, hybrid fluorescent systems with localized enhanced emission, and the general nanowire‐enhanced MEF effects associated to them, are highly relevant for developing nanoscale light‐emitting devices with high efficiency and intercoupled through nanofiber networks, highly sensitive optical sensors, and novel laser architectures. 相似文献
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Lingxiang Wang Liang Wang Xiangju Meng Feng‐Shou Xiao 《Advanced materials (Deerfield Beach, Fla.)》2019,31(50)
Supported metal nanoparticles are widely used as catalysts in the industrial production of chemicals, but still suffer from deactivation because of metal leaching and sintering at high temperature. In recent years, serious efforts have been devoted to developing new strategies for stabilizing metal nanoparticles. Recent developments for preparing sinter‐resistant metal‐nanoparticle catalysts via strong metal–support interactions, encapsulation with oxide or carbon layers and within mesoporous materials, and fixation in zeolite crystals, are briefly summarized. Furthermore, the current challenges and future perspectives for the preparation of highly efficient and extraordinarily stable metal‐nanoparticle‐based catalysts, and suggestions regarding the mechanisms involved in sinter resistance, are proposed. 相似文献
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Yanlin Feng Yun Chang Keqiang Xu Runxiao Zheng Xiaqing Wu Yan Cheng Haiyuan Zhang 《Small (Weinheim an der Bergstrasse, Germany)》2020,16(21)
The safety of metal oxide (MOx) nanoparticles (NPs) has been highly concerned because of their wide application and potential toxicological injury. The safe‐by‐design strategy is usually developed to make safer MOx NPs based on regulation of their physicochemical properties. In the present study, manganese oxide (Mn3O4) NPs, as a representative of insoluble toxic MOx NPs, are doped with a series of transition metal to regulate their conduction band energy (Ec) out of biological redox potential range (BRPR) or Fermi energy (Ef) far away from valence band energy (Ev), aiming at completely eliminating the toxicity or significantly reducing the toxicity. It is found that all these M‐doping cannot move Ec of Mn3O4 NPs out of the BRPR but zinc (Zn)‐, copper (Cu)‐, and chromium (Cr)‐doping do move Ef far away from Ev, where Zn‐doping results in the largest |Ef ? Ev| value. Various abiotic, in vitro and in vivo assessments reveal that Zn‐, Cu‐, and Cr‐doped Mn3O4 NPs can generate lower amount of ?OH and trigger weaker injury than Mn3O4 NPs, where Zn‐doped Mn3O4 NPs show the lowest toxicity. Regulating Ef far away from Ev becomes a feasible safe‐by‐design approach to achieve safe MOx NPs. 相似文献
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Junhao Ma Xingyu Xiao Yidong Zou Yuan Ren Xinran Zhou Xuanyu Yang Xiaowei Cheng Yonghui Deng 《Small (Weinheim an der Bergstrasse, Germany)》2019,15(46)
Controllable and efficient synthesis of noble metal/transition‐metal oxide (TMO) composites with tailored nanostructures and precise components is essential for their application. Herein, a general mercaptosilane‐assisted one‐pot coassembly approach is developed to synthesize ordered mesoporous TMOs with agglomerated‐free noble metal nanoparticles, including Au/WO3, Au/TiO2, Au/NbOx, and Pt/WO3. 3‐mercaptopropyl trimethoxysilane is applied as a bridge agent to cohydrolyze with metal oxide precursors by alkoxysilane moieties and interact with the noble metal source (e.g., HAuCl4 and H2PtCl4) by mercapto (? SH) groups, resulting in coassembly with poly(ethylene oxide)‐b‐polystyrene. The noble metal decorated TMO materials exhibit highly ordered mesoporous structure, large pore size (≈14–20 nm), high specific surface area (61–138 m2 g?1), and highly dispersed noble metal (e.g., Au and Pt) nanoparticles. In the system of Au/WO3, in situ generated SiO2 incorporation not only enhances their thermal stability but also induces the formation of ε‐phase WO3 promoting gas sensing performance. Owning to its specific compositions and structure, the gas sensor based on Au/WO3 materials possess enhanced ethanol sensing performance with a good response (Rair/Rgas = 36–50 ppm of ethanol), high selectivity, and excellent low‐concentration detection capability (down to 50 ppb) at low working temperature (200 °C). 相似文献
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Nanoparticle Cookies Derived from Metal‐Organic Frameworks: Controlled Synthesis and Application in Anode Materials for Lithium‐Ion Batteries
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Shuhai Wang Minqi Chen Yanyu Xie Yanan Fan Dawei Wang Ji‐Jun Jiang Yongguang Li Hansjörg Grützmacher Cheng‐Yong Su 《Small (Weinheim an der Bergstrasse, Germany)》2016,12(17):2365-2375
The capacity of anode materials plays a critical role in the performance of lithium‐ion batteries. Using the nanocrystals of oxygen‐free metal‐organic framework ZIF‐67 as precursor, a one‐step calcination approach toward the controlled synthesis of CoO nanoparticle cookies with excellent anodic performances is developed in this work. The CoO nanoparticle cookies feature highly porous structure composed of small CoO nanoparticles (≈12 nm in diameter) and nitrogen‐rich graphitic carbon matrix (≈18 at% in nitrogen content). Benefiting from such unique structure, the CoO nanoparticle cookies are capable of delivering superior specific capacity and cycling stability (1383 mA h g?1 after 200 runs at 100 mA g?1) over those of CoO and graphite. 相似文献
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DNA‐Assembled Core‐Satellite Upconverting‐Metal–Organic Framework Nanoparticle Superstructures for Efficient Photodynamic Therapy
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Liangcan He Michael Brasino Chenchen Mao Suehyun Cho Wounjhang Park Andrew P. Goodwin Jennifer N. Cha 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(24)
DNA‐mediated assembly of core–satellite structures composed of Zr(IV)‐based porphyrinic metal‐organic framework (MOF) and NaYF4,Yb,Er upconverting nanoparticles (UCNPs) for photodynamic therapy (PDT) is reported. MOF NPs generate singlet oxygen (1O2) upon photoirradiation with visible light without the need for additional small molecule, diffusional photosensitizers such as porphyrins. Using DNA as a templating agent, well‐defined MOF–UCNP clusters are produced where UCNPs are spatially organized around a centrally located MOF NP. Under NIR irradiation, visible light emitted from the UCNPs is absorbed by the core MOF NP to produce 1O2 at significantly greater amounts than what can be produced from simply mixing UCNPs and MOF NPs. The MOF–UCNP core–satellite superstructures also induce strong cell cytotoxicity against cancer cells, which are further enhanced by attaching epidermal growth factor receptor targeting affibodies to the PDT clusters, highlighting their promise as theranostic photodynamic agents. 相似文献
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Surface Engineering of Spherical Metal Nanoparticles with Polymers toward Selective Asymmetric Synthesis of Nanobowls and Janus‐Type Dimers
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Ben Liu Srinivas Thanneeru Aaron Lopes Lei Jin Meghan McCabe Jie He 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(20)
New synthetic methods capable of controlling structural and compositional complexities of asymmetric nanoparticles (NPs) are very challenging but highly desired. A simple and general synthetic approach to designing sophisticated asymmetric NPs by anisotropically patterning the surface of isotropic metallic NPs with amphiphilic block copolymers (BCPs) is reported. The selective galvanic replacement and seed‐mediated growth of a second metal can be achieved on the exposed surface of metal NPs, resulting in the formation of nanobowls and Janus‐type metal–metal dimers, respectively. Using Ag and Au NPs tethered with amphiphilic block copolymers of poly(ethylene oxide)‐block‐polystyrene (PEO‐b‐PS), anisotropic surface patterning of metallic NPs (e.g., Ag and Au) is shown to be driven by thermodynamical phase segregation of BCP ligands on isotropic metal NPs. Two proof‐of‐concept experiments are given on, i) synthesis of Au nanobowls by a selective galvanic replacement reaction on Janus‐type patched Ag/polymer NPs; and ii) preparation of Au–Pd heterodimers and Au–Au homodimers by a seed‐mediated growth on Janus‐type patched Au/polymer NPs. The method shows remarkable versatility; and it can be easily handled in aqueous solution. This synthetic strategy stands out as the new methodology to design and synthesis asymmetric metal NPs with sophisticated topologies. 相似文献
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The Role of Interfaces in Polyethylene/Metal‐Oxide Nanocomposites for Ultrahigh‐Voltage Insulating Materials
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Amir Masoud Pourrahimi Richard T. Olsson Mikael S. Hedenqvist 《Advanced materials (Deerfield Beach, Fla.)》2018,30(4)
Recent progress in the development of polyethylene/metal‐oxide nanocomposites for extruded high‐voltage direct‐current (HVDC) cables with ultrahigh electric insulation properties is presented. This is a promising technology with the potential of raising the upper voltage limit in today's underground/submarine cables, based on pristine polyethylene, to levels where the loss of energy during electric power transmission becomes low enough to ensure intercontinental electric power transmission. The development of HVDC insulating materials together with the impact of the interface between the particles and the polymer on the nanocomposites electric properties are shown. Important parameters from the atomic to the microlevel, such as interfacial chemistry, interfacial area, and degree of particle dispersion/aggregation, are discussed. This work is placed in perspective with important work by others, and suggested mechanisms for improved insulation using nanoparticles, such as increased charge trap density, adsorption of impurities/ions, and induced particle dipole moments are considered. The effects of the nanoparticles and of their interfacial structures on the mechanical properties and the implications of cavitation on the electric properties are also discussed. Although the main interest in improving the properties of insulating polymers has been on the use of nanoparticles, leading to nanodielectrics, it is pointed out here that larger microscopic hierarchical metal‐oxide particles with high surface porosity also impart good insulation properties. The impact of the type of particle and its inherent properties (purity and conductivity) on the nanocomposite dielectric and insulating properties are also discussed based on data obtained by a newly developed technique to directly observe the charge distribution on a nanometer scale in the nanocomposite. 相似文献
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Graphene‐Skeleton Heat‐Coordinated and Nanoamorphous‐Surface‐State Controlled Pseudo‐Negative‐Photoconductivity of Tiny SnO2 Nanoparticles
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Longwei Ding Nishuang Liu Luying Li Xing Wei Xianghui Zhang Jun Su Jiangyu Rao Congxing Yang Wenzhi Li Jianbo Wang Haoshuang Gu Yihua Gao 《Advanced materials (Deerfield Beach, Fla.)》2015,27(23):3525-3532
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Cong Wang Ang Li Chong Li Shengbai Zhang Hui Li Xiaoyuan Zhou Liming Hu Yibo Feng Kaiwen Wang Zhu Zhu Ruiwen Shao Yanhui Chen Peng Gao Shengcheng Mao Jun Huang Ze Zhang Xiaodong Han 《Advanced materials (Deerfield Beach, Fla.)》2019,31(52)
Metal oxides, as one of the mostly abundant and widely utilized materials, are extensively investigated and applied in environmental remediation and protection, and in energy conversion and storage. Most of these diverse applications are the result of a large diversity of the electronic states of metal oxides. Noticeably, however, many metal oxides present obstacles for applications in catalysis, mainly due to the lack of efficient active sites with desired electronic states. Here, the fabrication of single‐tungsten‐atom‐oxide (STAO) is demonstrated, in which the metal oxide's volume reaches its minimum as a unit cell. The catalytic mechanism in the STAO is determined by a new single‐site physics mechanism, named as quasi‐atom physics. The photogenerated electron transfer process is enabled by an electron in the spin‐up channel excited from the highest occupied molecular orbital to the lowest unoccupied molecular orbital +1 state, which can only occur in STAO with W5+. STAO results in a record‐high and stable sunlight photocatalytic degradation rate of 0.24 s?1, which exceeds the rates of available photocatalysts by two orders of magnitude. The fabrication of STAO and its unique quasi‐atom photocatalytic mechanism lays new ground for achieving novel physical and chemical properties using single‐metal‐atom oxides (SMAO). 相似文献