Nanoscience and technology

  • Article |

    Quasi-three-dimensional plasmonic crystals have potential uses in miniaturized photonics. In this study, a method is described to enhance plasmonic resonance in the crystals by coupling them to optical modes of Fabry–Perot type cavities, with possible applications in photonic and sensor components.

    • Debashis Chanda
    • , Kazuki Shigeta
    •  & John A. Rogers
  • Article |

    The manipulation of electrons forms the basis of modern technology, whereas electrical signalling processes in nature are based on ions and protons. Rolandi and colleagues present a proton transistor based on polysaccharide nanofibres, which can control the flow of protonic currents.

    • Chao Zhong
    • , Yingxin Deng
    •  & Marco Rolandi
  • Article |

    Plasmonic nanostructures can be used to manipulate objects larger than the wavelength of light but create thermal heating. In this work, the trapping and controlled rotation of nanoparticles is demonstrated using a plasmonic nanotweezer with a heat sink, predicting a reduction in heating compared with previous designs.

    • Kai Wang
    • , Ethan Schonbrun
    •  & Kenneth B. Crozier
  • Article |

    Protein microarrays are useful both in basic research and also in disease monitoring and diagnosis, but their dynamic range is limited. By using plasmonic gold substrates with near-infrared fluorescent enhancement, Tabakman et al. demonstrate a multiplexed protein array with improved detection limits and dynamic range.

    • Scott M. Tabakman
    • , Lana Lau
    •  & Hongjie Dai
  • Article |

    Hydrogels have a variety of applications including tissue engineering and controlled drug delivery. Here, liquid-crystal hydrogels are developed which transform into a fluid solution upon cooling; cells can be encapsulated in the gel at room temperature, then released at physiological temperatures.

    • Zhegang Huang
    • , Hyojin Lee
    •  & Myongsoo Lee
  • Article |

    Property coupling by heteroepitaxy is severely limited in material combinations with highly dissimilar bonding. This report presents a chemical boundary condition methodology to actively engineer two-dimensional film growth in such systems that otherwise collapse into island formation and rough morphologies.

    • Elizabeth A. Paisley
    • , Mark. D. Losego
    •  & Jon-Paul Maria
  • Article |

    Photodetection is believed to be among the most promising potential applications for graphene. Here, by combining graphene with plasmonic nanostructures, the efficiency of graphene-based photodetectors is increased by up to two orders of magnitude.

    • T.J. Echtermeyer
    • , L. Britnell
    •  & K.S. Novoselov
  • Article
    | Open Access

    High-power mechanical energy harvesting could be an alternative to batteries, but efficient energy conversion technology has been missing. Here, a novel mechanical-to-electrical energy conversion method is described that is based on reverse electrowetting and is uniquely suited for high-power energy harvesting.

    • Tom Krupenkin
    •  & J. Ashley Taylor
  • Article |

    Composites of carbon nanotubes and superconductors provide technologically important new, or improved, functionalities. Here, with a chemical solution approach, well-aligned carbon nanotube forests embedded in a superconducting NbC matrix are shown to effectively enhance the superconducting properties of NbC.

    • G.F. Zou
    • , H.M. Luo
    •  & Q.X. Jia
  • Article
    | Open Access

    Being able to determine the wetting properties of individual nanoparticles would aid the preparation of particles with controlled surface properties. Isaet al. develop an in situ freeze-fracture shadow-casting method and use this to determine structural and thermodynamic properties of various 10 nm particles at fluid interfaces.

    • Lucio Isa
    • , Falk Lucas
    •  & Erik Reimhult
  • Article
    | Open Access

    Chemical manipulation of fullerenes has allowed the production of heptagon-containing fullerenes, but they have not been synthesised using bottom-up approaches. Here, a heptagon-containing fullerene[68] is obtained as C68Cl6from a carbon arc plasma.

    • Yuan-Zhi Tan
    • , Rui-Ting Chen
    •  & Lan-Sun Zheng
  • Article
    | Open Access

    High critical temperature superconductors could be used to produce ideal electric power lines, but the misalignment of crystalline grain boundaries reduces current density. Here, pnictide superconductors are found to be more tolerant to misaligned grain boundaries than cuprates.

    • Takayoshi Katase
    • , Yoshihiro Ishimaru
    •  & Hideo Hosono
  • Article
    | Open Access

    Flux-closure patterns are rarely observed in ferroelectric materials and almost exclusively form at the nanoscale. McQuaidet al. report mesoscopic dipole closure patterns formed in free-standing single-crystal lamellae of BaTiO3, thought to result from an unusual set of experimental conditions.

    • R.G.P. McQuaid
    • , L.J. McGilly
    •  & J.M. Gregg
  • Article |

    Single-molecule magnets could be useful for the development of spintronic devices. Here single-molecule magnets are encapsulated in carbon nanotubes without affecting the properties of the guest molecules, which may be useful in the development of spintronic or high-density magnetic storage devices.

    • Maria del Carmen Giménez-López
    • , Fabrizio Moro
    •  & Andrei N. Khlobystov
  • Article |

    Covalent reactions on carbon nanotube surfaces typically occur at random positions on the hexagonal lattice. Denget al. show that Billups–Birch reductive alkylation takes place at, and propagates from, sp3defect sites, leading to confinement of the reaction fronts in the tubular direction.

    • Shunliu Deng
    • , Yin Zhang
    •  & YuHuang Wang
  • Article
    | Open Access

    Optical computing, involving on-chip integrated logic units, could provide improved performance over semiconductor-based computing. Here, a binary NOR gate is developed from cascaded OR and NOT gates in four-terminal plasmonic nanowire networks; the work could lead to new optical computing technologies.

    • Hong Wei
    • , Zhuoxian Wang
    •  & Hongxing Xu
  • Article |

    The unoccupied electronic levels of graphene are modified by corrugation, doping and presence of impurities. Here, the authors map discrete electronic domains within a single graphene sheet using scanning transmission X-ray microscopy and provide insight into the modification of unoccupied levels.

    • Brian J. Schultz
    • , Christopher J. Patridge
    •  & Sarbajit Banerjee
  • Article |

    Waveplates are used in optoelectronics to alter the polarization of light, but they do not typically perform achromatically, which is important for applications such as three-dimensional displays. Here, biologically inspired periodically multilayered structures are produced, which function as achromatic visible-light waveplates.

    • Yi-Jun Jen
    • , Akhlesh Lakhtakia
    •  & Jyun-Rong Lai
  • Article |

    Optoelectronic devices such as conventional semiconductor lasers are used to study the chaotic behaviour of nonlinear systems. Here chaos is observed for quantum-dot microlasers operating close to the quantum limit with potential for new directions in the study of chaos in quantum systems.

    • Ferdinand Albert
    • , Caspar Hopfmann
    •  & Ido Kanter
  • Article |

    Single nanoparticles are known to emit light intermittently, or 'blink', but the mechanisms describing this phenomenon are not fully understood. This study demonstrates that, for small clusters of blinking nanoparticles, the number of particles within a cluster dramatically influences blinking time.

    • Siying Wang
    • , Claudia Querner
    •  & Marija Drndic
  • Article |

    Encapsulating molecules within supramolecular frameworks for potential biological application is challenging. Bhatiaet al. incorporate a fluorescent polymer within an icosahedral DNA nanocapsule, and show that it can be used to target specific cells in vivoand map pH spatially and temporally.

    • Dhiraj Bhatia
    • , Sunaina Surana
    •  & Yamuna Krishnan
  • Article
    | Open Access

    Nanoparticles continue to find research and industrial applications, but no single technique exists to characterise their physical properties. Now, an analytical ultracentrifugation method is described which allows the simulataneous determination of nanoparticle size, density and molecular weight distribution.

    • Randy P. Carney
    • , Jin Young Kim
    •  & Osman M. Bakr
  • Article |

    Metal-based nanostructures offer a solution to scale down photonics to the nanoscale. Sorgeret al. directly demonstrate waveguiding of ultra-small propagating waves at visible and near-infrared frequencies using NSOM imaging, with the potential for nanoscale photonic applications such as bio-sensing.

    • Volker J. Sorger
    • , Ziliang Ye
    •  & Xiang Zhang
  • Article
    | Open Access

    Optical nanoantennas can be used for spectroscopic investigations at previously unattainable dimensions. Schumacheret al.describe time-resolved antenna-enhanced ultrafast nonlinear optical spectroscopy and determine the transient absorption signal of a single gold nanoparticle.

    • Thorsten Schumacher
    • , Kai Kratzer
    •  & Markus Lippitz
  • Article |

    Lithium–sulphur batteries may achieve higher energy densities than conventional lithium-ion cells, but the dissolution of sulphur intermediates is a continuing challenge. Here this problem is overcome using a cathode with a mesoporous structure that is able to accommodate intermediate polysulphide anions.

    • Xiulei Ji
    • , Scott Evers
    •  & Linda F. Nazar
  • Article
    | Open Access

    The conductance of single-molecule junctions is affected by the structure of the molecule and how it is bound to the electrodes, which may be examined using Raman spectroscopy. Liuet al. have developed 'fishing-mode' tip-enhanced Raman spectroscopy, which allows the simultaneous determination of conductance and Raman spectra.

    • Zheng Liu
    • , Song-Yuan Ding
    •  & Zhong-Qun Tian
  • Article
    | Open Access

    Wave mixing in optical resonators suffers from strong bandwidth constraints, hindering practical implementation. Morichettiet al. report travelling-wave four-wavemixing in coupled ring resonators, which combines the efficiency enhancement of resonant propagation with a wide-band conversion process.

    • Francesco Morichetti
    • , Antonio Canciamilla
    •  & Andrea Melloni
  • Article |

    Little is known about the effects of molecular crowding and confinement on biomolecule function. Castronovoet al. investigate the reactions of restriction enzymes with DNA confined in bushy matrices and find that the enzymes enter at the side of the matrix before diffusing two-dimensionally.

    • Matteo Castronovo
    • , Agnese Lucesoli
    •  & Giacinto Scoles
  • Article |

    Solid gold is most stable as a face-centred cubic structure, and stable colloidal gold with hexagonal close packing has not been produced. Huanget al.prepare square gold sheets with hexagonal close packing that are stable under ambient conditions.

    • Xiao Huang
    • , Shaozhou Li
    •  & Hua Zhang
  • Article |

    Nanometallic optical antennas can concentrate light into a deep-subwavelength volume for sensor and photovoltaic applications. Junet al. demonstrate an optical antenna design that achieves a high level of control over fluorescent emission for a wide range of nanoscale optical spectroscopy applications.

    • Young Chul Jun
    • , Kevin C.Y. Huang
    •  & Mark L. Brongersma
  • Article |

    Infrared cameras are used for night vision and in medical diagnostics, but currently only present monochrome images. Krishnaet al. demonstrate a monolithically intergrated plasmonic infrared quantum dot camera as a step towards coloured infrared imaging.

    • Sang Jun Lee
    • , Zahyun Ku
    •  & Sam Kyu Noh
  • Article
    | Open Access

    Electron–hole exchange interaction is an intrinsic property of semiconductors, which affects their fine structure. Brovelliet al. demonstrate a nanoengineering-based approach that provides control over the exchange interaction energy at nearly constant emission energy, which cannot be carried out using core-only nanocrystals.

    • S. Brovelli
    • , R.D. Schaller
    •  & V.I. Klimov
  • Article
    | Open Access

    In the pseudogap state of cuprates, although diamagnetic signals have been detected, a Meissner effect has never been observed. Morenzoni and colleagues probe the local diamagnetic response in the normal state of an underdoped layer showing that a 'barrier' layer exhibits a Meissner effect.

    • Elvezio Morenzoni
    • , Bastian M. Wojek
    •  & Ivan Božović
  • Article
    | Open Access

    Nanoantennas may be important for future photonic circuits; they combine an emitter or detector with free-space propagation of light. Dregelyet al. fabricate an array of 3D optical Yagi–Uda nanoantennas and show that radiofrequency antenna array concepts applied to the optical regime can provide improved directional properties.

    • Daniel Dregely
    • , Richard Taubert
    •  & Harald Giessen
  • Article |

    Bismuth ferrite has photoelectric properties that make it an attractive alternative for use in photovoltaic devices. Here, using photoelectric atomic force microscopy, the authors show that photogenerated carriers can be collected by the tip and suggest that this can be used in photoelectric applications.

    • Marin Alexe
    •  & Dietrich Hesse
  • Article
    | Open Access

    Embedding carbon fibres in polymer matrices provides significant gains in strength and stiffness. Here, the Raman G peak of carbon fibre is studied in relation to applied strain and referenced to graphene; the work could facilitate stress measurements of carbon fibre polymer composites.

    • Otakar Frank
    • , Georgia Tsoukleri
    •  & Costas Galiotis
  • Article |

    Single-molecule force spectroscopy is used to study single molecule interactions, but probing short-lived events is difficult. Here, a nanomechanical interface is developed, which allows the study of microsecond timescale interactions.

    • Mingdong Dong
    •  & Ozgur Sahin
  • Article |

    Graphene and InAs nanowires are both promising materials for coherent spin manipulation, but coupling between a quantum system and its environment leads to decoherence. Here, the contribution of electron–phonon coupling to decoherence in graphene and InAs nanowire is studied.

    • P. Roulleau
    • , S. Baer
    •  & T. Ihn
  • Article |

    Cold ion traps have not previously been used to study sliding friction between crystal lattices. Here, Benassiet al. use simulations to show that cold ion traps could be used for detailed investigation of atomic scale friction.

    • A. Benassi
    • , A. Vanossi
    •  & E. Tosatti
  • Article
    | Open Access

    In molecular spintronics, the spin state of a molecule may be switched by changing the molecular structure. Here, the spin of a single-molecule magnet is switched by applying an electric current using a scanning tunnelling microscope, which may aid in information coding at the single-molecule level.

    • Tadahiro Komeda
    • , Hironari Isshiki
    •  & Masahiro Yamashita
  • Article |

    Lenses are restricted by diffraction to imaging features roughly the size of visible wavelengths. Wanget al. develop a white-light nanoscope that uses optically transparent spherical silica lenses to virtually image, in the far-field, features down to 50 nm resolution.

    • Zengbo Wang
    • , Wei Guo
    •  & Minghui Hong
  • Article
    | Open Access

    New memory devices are being developed to overcome the limitations of conventional silicon-based flash memory. Here, a non-volatile memory design is reported that uses a micromechanical cantilever to charge and discharge a floating gate, which controls charge transport through a carbon nanotube field-effect transistor.

    • Sang Wook Lee
    • , Seung Joo Park
    •  & Yung Woo Park