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https://www.readbyqxmd.com/read/27911977/selective-inactivation-of-enzymes-conjugated-to-nanoparticles-using-tuned-laser-illumination
#1
Asaf Ilovitsh, Pazit Polak, Zeev Zalevsky, Orit Shefi
We report a novel method for specific deactivation of conjugated enzymes using laser-heated gold nanoparticles. Current methods involve treatment of the entire solution, thereby inactivating all bioactive components. Our method enables inactivation of only a single or subset of targeted enzymes. The selected enzyme is pre-conjugated to gold nanoparticles, which are specifically heated by a laser tuned to their surface plasmon resonance. We demonstrate inactivation of a selected enzyme, glucose oxidase, within a mixture of biomolecules...
December 2, 2016: Cytometry. Part A: the Journal of the International Society for Analytical Cytology
https://www.readbyqxmd.com/read/27911819/programmable-and-reversible-plasmon-mode-engineering
#2
Ankun Yang, Alexander J Hryn, Marc R Bourgeois, Won-Kyu Lee, Jingtian Hu, George C Schatz, Teri W Odom
Plasmonic nanostructures with enhanced localized optical fields as well as narrow linewidths have driven advances in numerous applications. However, the active engineering of ultranarrow resonances across the visible regime-and within a single system-has not yet been demonstrated. This paper describes how aluminum nanoparticle arrays embedded in an elastomeric slab may exhibit high-quality resonances with linewidths as narrow as 3 nm at wavelengths not accessible by conventional plasmonic materials. We exploited stretching to improve and tune simultaneously the optical response of as-fabricated nanoparticle arrays by shifting the diffraction mode relative to single-particle dipolar or quadrupolar resonances...
November 28, 2016: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/27910853/holographic-free-electron-light-source
#3
Guanhai Li, Brendan P Clarke, Jin-Kyu So, Kevin F MacDonald, Nikolay I Zheludev
Recent advances in the physics and technology of light generation via free-electron proximity and impact interactions with nanostructures (gratings, photonic crystals, nano-undulators, metamaterials and antenna arrays) have enabled the development of nanoscale-resolution techniques for such applications as mapping plasmons, studying nanoparticle structural transformations and characterizing luminescent materials (including time-resolved measurements). Here, we introduce a universal approach allowing generation of light with prescribed wavelength, direction, divergence and topological charge via point-excitation of holographic plasmonic metasurfaces...
December 2, 2016: Nature Communications
https://www.readbyqxmd.com/read/27910072/enhancing-surface-plasmon-resonance-detection-using-nanostructured-au-chips
#4
Ivan Indutnyi, Yuriy Ushenin, Dirk Hegemann, Marianne Vandenbossche, Victor Myn'ko, Mariia Lukaniuk, Petro Shepeliavyi, Andrii Korchovyi, Roman Khrystosenko
The increase of the sensitivity of surface plasmon resonance (SPR) refractometers was studied experimentally by forming a periodic relief in the form of a grating with submicron period on the surface of the Au-coated chip. Periodic reliefs of different depths and spatial frequency were formed on the Au film surface using interference lithography and vacuum chalcogenide photoresists. Spatial frequencies of the grating were selected close to the conditions of Bragg reflection of plasmons for the working wavelength of the SPR refractometer and the used environment (solution of glycerol in water)...
December 2016: Nanoscale Research Letters
https://www.readbyqxmd.com/read/27908751/enhanced-potency-of-bivalent-small-molecule-gp41-inhibitors
#5
Vladimir Sofiyev, Hardeep Kaur, Beth A Snyder, Priscilla A Hogan, Roger G Ptak, Peter Hwang, Miriam Gochin
Low molecular weight peptidomimetic inhibitors with hydrophobic pocket binding properties and moderate fusion inhibitory activity against HIV-1 gp41-mediated cell fusion were elaborated by increasing the available surface area for interacting with the heptad repeat-1 (HR1) coiled coil on gp41. Two types of modifications were tested: 1) increasing the overall hydrophobicity of the molecules with an extension that could interact in the HR1 groove, and 2) forming symmetrical dimers with two peptidomimetic motifs that could potentially interact simultaneously in two hydrophobic pockets on the HR1 trimer...
November 19, 2016: Bioorganic & Medicinal Chemistry
https://www.readbyqxmd.com/read/27908641/free-energy-perturbation-calculation-of-relative-binding-free-energy-between-broadly-neutralizing-antibodies-and-the-gp120-glycoprotein-of-hiv-1
#6
Anthony J Clark, Tatyana Gindin, Baoshan Zhang, Lingle Wang, Robert Abel, Colleen S Murret, Fang Xu, Amy Bao, Nina J Lu, Tongqing Zhou, Peter D Kwong, Lawrence Shapiro, Barry Honig, Richard A Friesner
Direct calculation of relative binding affinities between antibodies and antigens is a long-sought goal. However, despite substantial efforts, no generally applicable computational method has been described. Here we describe a systematic free energy perturbation (FEP) protocol and calculate the binding affinities between the gp120 envelope glycoprotein of HIV-1 and three broadly neutralizing antibodies (bNAbs) of the VRC01 class. The protocol has been adapted from successful studies of small molecules to address the challenges associated with modeling protein-protein interactions...
November 28, 2016: Journal of Molecular Biology
https://www.readbyqxmd.com/read/27906407/active-magnetoplasmonic-split-ring-ring-nanoantennas
#7
Hua Yu Feng, Feng Luo, Raul Arenal, Luc Henrard, Fernando García, Gaspar Armelles, Alfonso Cebollada
Here we present a novel active system, which combines the plasmon resonance enhancement of the magneto-optical activity in magnetoplasmonic nanostructures and the strong electromagnetic field localization of split ring resonators. The structures consist of a gold split ring resonator placed on top of a gold nanoring in the section of which a Co nanodot is inserted. By placing the split ring gap on top of the nanodot, and continuously varying the split ring gap opening, we are able to tune and enhance the electromagnetic field intensity in the Co nanodot, as confirmed experimentally by EELS and numerically using DDA simulation methods...
December 1, 2016: Nanoscale
https://www.readbyqxmd.com/read/27906405/study-of-graphene-plasmons-in-graphene-mos2-heterostructures-for-optoelectronic-integrated-devices
#8
Ruina Liu, Baoxin Liao, Xiangdong Guo, Debo Hu, Hai Hu, Luojun Du, Hua Yu, Guangyu Zhang, Xiaoxia Yang, Qing Dai
The performance of electronic circuits is becoming limited by on-chip digital information transmission. Graphene plasmons with ultra-high confinement and low damping rates offer an effective solution to this problem as they allow for the implementation of optical interconnects. However, direct contact with the semiconductor always deteriorates the plasmonic properties due to large damping of the plasmon in the semiconductor. Here, we studied graphene plasmons in heterostructures of graphene and monolayer MoS2 which represents a promising semiconductor for next-generation electronic devices...
December 1, 2016: Nanoscale
https://www.readbyqxmd.com/read/27906396/gadolinium-oxysulfide-coated-gold-nanorods-with-improved-stability-and-dual-modal-magnetic-resonance-photoacoustic-imaging-contrast-enhancement-for-cancer-theranostics
#9
Tao Guo, Yan Lin, Zhi Li, Shan Chen, Guoming Huang, Huirong Lin, Jun Wang, Gang Liu, Huang-Hao Yang
Gold nanorods (GNRs) are emerging as a promising nanoplatform for cancer theranostics because of their unique optical properties. However, they still suffer from many limitations, such as high cytotoxicity, low thermodynamic and biological stability, and a tedious process for integrating other imaging modalities, for further practical biomedical applications. In this work, a strategy by one-step coating of Gd2O2S around GNRs is reported to address these limitations of GNRs. After the coating of the Gd2O2S shell, the as-fabricated Gd2O2S coated GNRs (GNRs@Gd2O2S) show enhanced biocompatibility and photostability, and tunable localized surface plasmon resonance...
December 1, 2016: Nanoscale
https://www.readbyqxmd.com/read/27906395/regioselective-plasmonic-nano-assemblies-for-bimodal-sub-femtomolar-dopamine-detection
#10
Fengli Gao, Liqiang Liu, Gang Cui, Liguang Xu, Xiaoling Wu, Hua Kuang, Chuanlai Xu
Reliable and ultrasensitive quantification of dopamine (DA) is essential in the precise diagnotherapy of neurological diseases. In this study, dual mode counterpropagating-responsive gold@silver nanoparticle-gold nanorod (Au@AgNP-AuNR) nano-assemblies were fabricated for the precise quantification of DA. The plasmonic Au@AgNP-AuNR assemblies possessed high surface-enhanced Raman scattering (SERS) activity and strong fluorescence quenching, due to the prominent electromagnetic enhancement between the hotspots of the assemblies...
December 1, 2016: Nanoscale
https://www.readbyqxmd.com/read/27906371/depolarization-of-a-randomly-distributed-plasmonic-meander-metasurface-characterized-by-mueller-matrix-spectroscopic-ellipsometry
#11
Liwei Fu, Audrey Berrier, Huiyu Li, Philipp Schau, Karsten Frenner, Martin Dressel, Wolfgang Osten
Metallic nanostructures offer efficient solutions in polarization control with a very low thickness. In this report, we investigate the optical properties of a nano-fabricated plasmonic pseudo-depolarizer using Mueller matrix spectroscopic ellipsometry in transmission configuration. The depolarizer is composed of 256 square cells, each containing a periodically corrugated metallic film with random orientation. The full Mueller matrix was analyzed as a function of incident angle in a range between 0 and 20° and over the whole rotation angle range...
November 28, 2016: Optics Express
https://www.readbyqxmd.com/read/27906356/enhanced-infrared-transmission-through-gold-nanoslit-arrays-via-surface-plasmons-in-continuous-graphene
#12
Zizhuo Liu, Koray Aydin
Graphene is a monolayer plasmonic material that has been widely studied in the area of plasmonics and nanophotonics. Combining graphene with traditional plasmonic structures provides new opportunities and challenges. One particular application for nanostructured metals is enhanced optical transmission. However, extraordinary transmission (EOT) is known to have a frequency-selective performance due to size and periodicity of the nanohole arrays. Here, we propose to use a continuous graphene layer to enhance transmission through gold nanoslit arrays at mid-infrared (mid-IR) wavelengths...
November 28, 2016: Optics Express
https://www.readbyqxmd.com/read/27906355/control-of-the-two-photon-fluorescence-of-quantum-dots-coupled-to-silver-nanowires
#13
Weijie Mai, Xiaokang Song, Ping Jiang, Wenzhong Wang, Li Yu, Jiasen Zhang
Plasmon-based fluorescence modulation has led to important advances in various fields and has paved the way toward promising scientific research aimed at enabling new applications. However, the modulation of fluorescence properties based on both localized surface plasmon (LSP) and cavity modes of propagating surface plasmon polaritons (SPPs) are rarely reported. Here, we raster scanned a hybrid nanowire (HNW) with quantum dots (QDs) adsorbed onto a Ag nanowire (NW) and obtained two-photon fluorescence (TPF) maps of the intensity and decay rate...
November 28, 2016: Optics Express
https://www.readbyqxmd.com/read/27906345/grating-coupling-based-excitation-of-bloch-surface-waves-for-lab-on-fiber-optrodes
#14
Michele Scaravilli, Giuseppe Castaldi, Andrea Cusano, Vincenzo Galdi
In this paper, we investigate the possibility to excite Bloch surface waves (BSWs) on the tip of single-mode optical fibers. Within this framework, after exploring an idealized, proof-of-principle grating-coupling-based scheme for on-tip excitation of BSWs, we focus on an alternative configuration that is more robust with respect to fabrication-related non-idealities. Subsequently, with a view towards label-free chemical and biological sensing, we present a specific design aimed at enhancing the sensitivity (in terms of wavelength shift) of the arising resonance with respect to changes in the refractive properties of the surrounding environment...
November 28, 2016: Optics Express
https://www.readbyqxmd.com/read/27906344/giant-circular-dichroism-and-its-reversal-in-solid-and-inverse-plasmonic-gammadion-shaped-structures
#15
Shan Wu, Pingping Qu, Jianqiang Liu, Dandan Lei, Kaiyin Zhang, Shutao Zhao, Yongyuan Zhu
Chiral plasmonic structures have been shown to possess large circular dichroism (CD) responses. Here, we investigate the CD responses in a solid and inverse metallic structure composed of a stacked right-twisted gammadion metallic nanoparticle and a left-twisted gammadion nanoaperture array, where a giant circular dichroism is achieved. In addition, the sign of the CD responses can be reversed through the changes of the geometric parameters. Further analysis reveals that the Fabry-Perot (F-P) resonance of cross-polarization conversion of electric field governs the change of the CD...
November 28, 2016: Optics Express
https://www.readbyqxmd.com/read/27906327/optical-force-enhancement-and-annular-trapping-by-plasmonic-toroidal-resonance-in-a-double-disk-metastructure
#16
Ren-Chao Jin, Jie Li, Ying-Hua Wang, Ming-Jie Zhu, Jia-Qi Li, Zheng-Gao Dong
Optical forces can be enhanced by surface plasmon resonances with various interesting characteristics. Here, we numerically calculated the optical forces enhanced by a new kind of toroidal dipolar resonance in a double-disk metastructure. The results show that this kind of optical force is competitive with ordinary plasmonic forces and typically can reach-182.5pNμm<sup>2</sup>mW<sup>-1</sup>. Influences of geometric parameters are discussed for the enhancement characteristic of optical force...
November 28, 2016: Optics Express
https://www.readbyqxmd.com/read/27906326/improving-the-luminescence-enhancement-of-hybrid-au-nanoparticle-monolayer-mos-sub-2-sub-by-focusing-radially-polarized-beams
#17
Di Liu, Le Yu, Xiao Xiong, Lei Yang, Yan Li, Ming Li, Hai-Ou Li, Gang Cao, Ming Xiao, Bin Xiang, Chang-Jun Min, Guang-Can Guo, Xi-Feng Ren, Guo-Ping Guo
Monolayer transition-metal dichalcogenides (TMDs) have grown as fantastic building blocks for optoelectronic applications, owing to their direct band gap, transparency, and mechanical flexibility. Since the luminescence of monolayer TMDs suffers from low light absorption and emission, surface plasmons, which confine light at subwavelength and enhance the local electric field, are utilized to boost both excitation and emission fields of TMDs, enabling strong light-matter interaction at the nano-scale. Meanwhile, radially-polarized beams (RPBs) as new and attractive excitation source have found many applications in surface plasmon polaritons, optical tweezer and so on...
November 28, 2016: Optics Express
https://www.readbyqxmd.com/read/27906315/effect-of-non-conformal-gold-deposition-on-sers-related-plasmonic-effects
#18
Swe Zin Oo, Martin D B Charlton
Recently, a comprehensive three dimensional computational model based on rigorous coupled wave analysis (RCWA) has been developed to investigate the properties of surface plasmons resident on metal coated arrays of inverted pyramidal pits used for SERS sensing applications in the form of 'klarite'. This simulation tool allows the identification of a variety of dispersive features including propagating and localized surface plasmons as well as simple diffraction relating to the influence of geometrical features...
November 28, 2016: Optics Express
https://www.readbyqxmd.com/read/27906313/experimental-study-on-the-transition-of-plasmonic-resonance-modes-in-double-ring-dimers-by-conductive-junctions-in-the-terahertz-regime
#19
Huifang Zhang, Chun Li, Caihong Zhang, Xueqian Zhang, Jianqiang Gu, Biaobing Jin, Jiaguang Han, Weili Zhang
Plasmonic dimers that made from two subwavelength particles have drawn much attention in the recent years, which are quite promising in local field enhancement, sensing, high frequency conductance probing and electron tunneling. In this work, we experimentally investigate the mode transition effect of different plasmonic resonances in double-ring dimers when introducing conductive junction at the dimer gap in the terahertz regime. Without the junction, the dimers support a single dipolar bonding dimer plasmonic (BDP) mode...
November 28, 2016: Optics Express
https://www.readbyqxmd.com/read/27906303/higher-order-surface-plasmon-contributions-to-passive-and-active-plasmonic-interferometry
#20
Dongfang Li, Jing Feng, Domenico Pacifici
We compare the intensity modulation of passive light transmission and active fluorescence emission in planar plasmonic interferometers consisting of a nano-scale hole flanked by circular grooves etched in a silver film. Discrete fast Fourier transform applied to plasmonic interferograms - i.e., optical interferograms obtained by varying the propagation phase of surface plasmon polaritons (SPPs) - reveals higher-order interference effects that can be enhanced by optimizing in-plane SPP scattering and reflection...
November 28, 2016: Optics Express
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