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Soo Hyeon Lim, Eun-Young Ahn, Youmie Park
Gold nanoparticles were synthesized using a water extract of Artemisia capillaris (AC-AuNPs) under different extract concentrations, and their catalytic activity was evaluated in a 4-nitrophenol reduction reaction in the presence of sodium borohydride. The AC-AuNPs showed violet or wine colors with characteristic surface plasmon resonance bands at 534~543 nm that were dependent on the extract concentration. Spherical nanoparticles with an average size of 16.88 ± 5.47~29.93 ± 9.80 nm were observed by transmission electron microscopy...
December 2016: Nanoscale Research Letters
Roger M Pallares, Michel Bosman, Nguyen T K Thanh, Xiaodi Su
A hybrid system made of gold nanorods (AuNRs) and double-stranded DNA (dsDNA) is used to build a versatile multi-logic gate platform, capable of performing six different logic operations. The sequence-specific binding of transcription factors to the DNA drives the optical response of the design.
October 26, 2016: Nanoscale
Alexander W Peterson, Michael Halter, Anne L Plant, John T Elliott
Surface plasmon resonance (SPR) imaging allows real-time label-free imaging based on index of refraction and changes in index of refraction at an interface. Optical parameter analysis is achieved by application of the Fresnel model to SPR data typically taken by an instrument in a prism based figuration. We carry out SPR imaging on a microscope by launching light into a sample and collecting reflected light through a high numerical aperture microscope objective. The SPR microscope enables spatial resolution that approaches the diffraction limit and has a dynamic range that allows detection of subnanometer to submicrometer changes in thickness of biological material at a surface...
September 2016: Review of Scientific Instruments
Yuan Li, Jeffrey D Cain, Eve D Hanson, Akshay A Murthy, Shiqiang Hao, Fengyuan Shi, Qianqian Li, Christopher Wolverton, Xinqi Chen, Vinayak P Dravid
There are emerging opportunities to harness diverse and complex geometric architectures based on nominal two-dimensional atomically layered structures. Herein we report synthesis and properties of a new core-shell heterostructure, termed Au@MoS2, where the Au nanoparticle is snugly and contiguously encapsulated by few shells of MoS2 atomic layers. The heterostructures were synthesized by direct growth of multilayer fullerene-like MoS2 shell on Au nanoparticle cores. The Au@MoS2 heterostructures exhibit interesting light-matter interactions due to the structural curvature of MoS2 shell and the plasmonic effect from the underlying Au nanoparticle core...
October 26, 2016: Nano Letters
Woo-Ram Lee, Jose Navarrete, Brian Evanko, Galen D Stucky, Syed Mubeen, Martin Moskovits
A plasmonic liquid junction photovoltaic cell with greatly improved power conversion efficiency is described. When illuminated with simulated sunlight, the device (Au-TiO2/V(3+)(0.018 M), V(2+)(0.182 M)/Pt) reproducibly and sustainably produces an VOC of 0.50 V and a JSC of 0.5 mA cm(-2), corresponding to a power conversion efficiency of 0.095%.
October 26, 2016: Chemical Communications: Chem Comm
Anna L Gould, Kevin Rossi, C Richard A Catlow, Francesca Baletto, Andrew J Logsdail
We present a study of the transitional pathways between high-symmetry structural motifs for AgAu nanoparticles, with a specific focus on controlling the energetic barriers through chemical design. We show that the barriers can be altered by careful control of the elemental composition and chemical arrangement, with core@shell and vertex-decorated arrangements being specifically influential on the barrier heights. We also highlight the complexity of the potential and free energy landscapes for systems where there are low-symmetry geometric motifs that are energetically competitive to the high-symmetry arrangements...
October 26, 2016: Journal of Physical Chemistry Letters
Evan A Dubiel, Bruno Martin, Sylvain Vigier, Patrick Vermette
A quartz crystal microbalance (QCM) was constructed to assess if such a biosensor has value as a complementary real-time label-free analysis platform for the biopharmaceutical industry. This was achieved through modifying QCM crystals with a low-fouling carboxymethyl-dextran layer bearing Protein A, and then injecting solutions containing Etanercept (i.e., Enbrel(®)) into the QCM chambers. The kinetics of Enbrel(®) - Protein A interactions was modeled using the Langmuir binding model and Enbrel(®) concentrations between 0...
October 19, 2016: Colloids and Surfaces. B, Biointerfaces
Jangheon Kim, Janghyeon Lee, Soohyun Kim, Wonsuk Jung
We generate networks and carbonization between individualized single-walled carbon nanotubes (SWCNTs) by an optimized plasmonic heating process using a halogen lamp to improve electrical properties for flow-induced energy harvesting. These properties were characterized by Raman spectra, a field-emission-scanning probe, transmission electron microscopy, atomic force microscopy and thermo-graphic camera. The electrical sheet resistance of carbonized SWCNTs was decreased to 2.71 , 2.5 times smaller than normal-SWCNTs...
October 25, 2016: ACS Applied Materials & Interfaces
Sujin Ahn, Peng Zhang, Hyunung Yu, Seungah Lee, Seong Ho Kang
Super-localization of immunoplasmonic nanotags on antibody-bound gold-nanoislands (GNIs) along the x, y coordinates was determined using total internal reflection scattering-based super-resolution microscopy (TIRS-SRM) at subdiffraction limit resolu-tion. Individual immunoplasmonic nanotags (20-nm silver nanoparticles) and 100-nm GNIs were selectively acquired in the eva-nescent field layer by wavelength-dependent plasmonic scattering using two illumination lasers (405 nm and 635 nm, respectively). Alpha-fetoprotein (AFP), a liver cancer-related model protein, was immobilized as a target molecule on the GNI arrays...
October 25, 2016: Analytical Chemistry
Tianran Lin, Yarong Wu, Zhihong Li, Zhiping Song, Liangqia Guo, FengFu Fu
Colorimetric detection of biogenic amines, well-known indicators of food spoilage, plays an important role for monitoring of food safety. However, common colorimetric sensors for biogenic amines suffer from low color resolution or complicated design and intricate output for the end-users. Herein, we explored a simple but effective strategy for visual monitoring of biogenic amines with multiple color change based on hydrolysis-induced silver metallization reaction to tune the localized surface plasmon resonance (LSPR) adsorption of Au nanorods (NRs)...
October 25, 2016: Analytical Chemistry
Sean Murphy, Sarah Jaber, Cameron Ritchie, Matthias Karg, Paul Mulvaney
Hydrophobic forces play a key role in the processes of collapse and re-swelling of thermoresponsive polymers. However little is known about the dynamics of these processes. Here, thermoresponsive poly(N-isopropylacrylamide) encapsulated gold nanoparticles (Au-PNIPAM) are heated via nanosecond laser flash photolysis. Photothermal heating via excitation of the localized surface plasmon resonance of the Au nanoparticle cores results in rapid PNIPAM shell collapse within the 10 ns pulse width of the laser. Remarkably, re-swelling of the polymer shell takes place in less than 100 nanoseconds...
October 25, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Atsushi Yamada, Daniel Neuhauser, Renaud Vallée
We propose a new type of nanodevice, capable of both path-selectivity and anisotropic lasing, that is based on loss-compensation and amplification by a localized plasmon polariton. The nanodevice is a Y-shaped plasmonic nanostructure embedded in an anisotropic host medium with gain. The anisotropy leads to path selectivity, an effect which is more pronounced once gain is included. Such a device is potentially realizable via bottom-up techniques. The path-selectivity may be coupled with activation of a rotation of the anisotropic host medium for inducing a light-guiding switching functionality...
October 25, 2016: Nanoscale
Zilong Wu, Glen Kelp, Maruthi Nagavalli Yogeesh, Wei Li, Kyle M McNicholas, Andrew Briggs, Bharath Bangalore Rajeeva, Deji Akinwande, Seth R Bank, Gennady Shvets, Yuebing Zheng
There has been strong interest in developing multi-band plasmonic metasurfaces for multiple optical functions on single platforms. Herein, we developed Au moiré metasurface patches (AMMP), which leverage the tunable multi-band responses of Au moiré metasurfaces and the additional field enhancements of the metal-insulator-metal configuration to achieve dual-band plasmon resonance modes in near-infrared and mid-infrared regimes with high field enhancement. Furthermore, we demonstrate the multifunctional applications of AMMP, including surface-enhanced infrared spectroscopy, optical capture and patterning of bacteria, and photothermal denaturation of proteins...
October 25, 2016: Nanoscale
Tobias Stauber, Heinerich Kohler
The charge susceptibility of twisted bilayer graphene is investigated in the Dirac cone, respectively random-phase approximation. For small enough twist angles Θ≦2(o) we find weakly Landau damped interband plasmons, i.~e., collective excitonic modes which exist in the undoped material, with an almost constant energy dispersion. In this regime, the loss function can be described as a Fano resonance and we argue that these excitations arise from the interaction of quasi-localised states with the incident light field...
October 24, 2016: Nano Letters
Kamlesh Shrivas, Pathik Maji, Khemchand Dewangan
We report a simple, selective and sensitive colorimetric assay for onsite determination of Ni(II) and Ba(II) from river, pond and tap water samples using the localized surface plasmon resonance (LSPR) of malonate capped gold nanoparticles (AuNPs) as a chemical sensor. The method is based on the color change and red shift of LSPR absorption band in visible region that caused by the aggregation of NPs because of the coordination complex between Ba(II) and Ni(II) with carboxylate ions of malonate capped AuNPs...
October 17, 2016: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
K Anand, C Tiloke, A Phulukdaree, B Ranjan, A Chuturgoon, S Singh, R M Gengan
The biosynthesis of nanostructured biopalladium nanoparticles (PdNPs) from an aqueous solution of crystalline palladium acetate is reported. For the synthesised PdNPs in solution, an agroforest biomass waste petal of Moringa oleifera derived bis-phthalate was used as natural reducing and biocapping agents. Continuous absorption in the UV region and subsequent brown colour change confirmed the formation of PdNPs. A strong surface plasmon peak for PdNPs occurred at 460nm. PdNPs were characterized by SEM with EDX, FTIR, TEM and DLS...
September 29, 2016: Journal of Photochemistry and Photobiology. B, Biology
Pablo Alonso-González, Alexey Y Nikitin, Yuanda Gao, Achim Woessner, Mark B Lundeberg, Alessandro Principi, Nicolò Forcellini, Wenjing Yan, Saül Vélez, Andreas J Huber, Kenji Watanabe, Takashi Taniguchi, Félix Casanova, Luis E Hueso, Marco Polini, James Hone, Frank H L Koppens, Rainer Hillenbrand
Terahertz (THz) fields are widely used for sensing, communication and quality control. In future applications, they could be efficiently confined, enhanced and manipulated well below the classical diffraction limit through the excitation of graphene plasmons (GPs). These possibilities emerge from the strongly reduced GP wavelength, λp, compared with the photon wavelength, λ0, which can be controlled by modulating the carrier density of graphene via electrical gating. Recently, GPs in a graphene/insulator/metal configuration have been predicted to exhibit a linear dispersion (thus called acoustic plasmons) and a further reduced wavelength, implying an improved field confinement, analogous to plasmons in two-dimensional electron gases (2DEGs) near conductive substrates...
October 24, 2016: Nature Nanotechnology
Selvaraj Naveenraj, Ramalinga Viswanathan Mangalaraja, Jerry J Wu, Abdullah M Asiri, Sambandam Anandan
Gold triangular nanoprisms and nanodecahedra (pentagonal bipyramids) were synthesized in the absence and presence of nanoseeds by a simple solvothermal synthesis through the reduction of Auric Chloride (HAuCl4) with poly(vinylpyrrolidone) (PVP) in N,N-dimethylformamide (DMF), respectively. These gold nanoparticles exhibit two plasmon resonance bands. The interaction of these gold nanoparticles with luminol was investigated using UV-vis and fluorescence spectroscopy since hefty number of environmental and biological sensors are based on the combination of luminol and gold nanoparticles...
October 24, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Han Yu, Quan Sun, Kosei Ueno, Tomoya Oshikiri, Atsushi Kubo, Yasutaka Matsuo, Hiroaki Misawa
The extraordinary optical properties of coupled plasmonic nanostructures make these materials potentially useful in many applications; thus, they have received enormous attentions in basic and applied research. Coupled plasmon modes have been characterized predominantly using far-field spectroscopy. In near-field spectroscopy, the spectral response of local field enhancement in coupled plasmonic nanostructures remains largely unexplored, especially experimentally. Here, we investigate the coupled gold dolmen nanostructures in the near field using photoemission electron microscopy (PEEM), with wavelength-tunable femtosecond laser pulses as an excitation source...
October 24, 2016: ACS Nano
Xueling Feng, Kaihuan Zhang, Peng Chen, Xiaofeng Sui, Mark A Hempenius, Bo Liedberg, G Julius Vancso
Highly swellable, dual-responsive hydrogels, consisting of thermo-responsive poly(N-isopropylacrylamide) (PNIPAM) and redox-responsive poly(ferrocenylsilane) (PFS) based poly(ionic liquid)s (PILs) are formed by photo-polymerization. PFS chains bearing cross-linkable vinylimidazolium (VIm) side groups are copolymerized with NIPAM in aqueous solutions under ultraviolet light (λ = 365 nm) in the presence of a photoinitiator. The PFS-PILs serve as a macro-cross-linker and also provide redox responsiveness. The swelling ratio, morphology, and lower critical solution temperature (LCST) of the hydrogels are studied as a function of the PNIPAM/PFS ratio...
October 24, 2016: Macromolecular Rapid Communications
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