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https://www.readbyqxmd.com/read/29331861/synthesis-of-colloidal-silver-nanoparticle-clusters-and-their-application-in-ascorbic-acid-detection-by-sers
#1
Jorge L Cholula-Díaz, Diana Lomelí-Marroquín, Bidhan Pramanick, Alfonso Nieto-Argüello, Luis A Cantú-Castillo, Hyundoo Hwang
Ascorbic acid (vitamin C) has an essential role in the human body mainly due to its antioxidant function. In this work, metallic silver nanoparticle (AgNP) colloids were used in SERS experiments to detect ascorbic acid in aqueous solution. The AgNPs were synthesized by a green method using potato starch as reducing and stabilizing agent, and water as the solvent. The optical properties of the yellowish as-synthesized silver colloids were characterized by UV-vis spectroscopy, in which besides a typical band at 410 nm related to the localized surface plasmon resonance of the silver nanoparticles, a shoulder band around 500 nm, due to silver nanoparticle cluster formation, is presented when relatively higher concentrations of starch are used in the synthesis...
December 29, 2017: Colloids and Surfaces. B, Biointerfaces
https://www.readbyqxmd.com/read/29331424/ultra-narrow-surface-lattice-resonances-in-plasmonic-metamaterial-arrays-for-biosensing-applications
#2
Artem Danilov, Gleb Tselikov, Fan Wu, Vasyl G Kravets, Igor Ozerov, Frederic Bedu, Alexander N Grigorenko, Andrei V Kabashin
When excited over a periodic metamaterial lattice of gold nanoparticles (~ 100nm), localized plasmon resonances (LPR) can be coupled by a diffraction wave propagating along the array plane, which leads to a drastic narrowing of plasmon resonance lineshapes (down to a few nm full-width-at-half-maximum) and the generation of singularities of phase of reflected light. These phenomena look very promising for the improvement of performance of plasmonic biosensors, but conditions of implementation of such diffractively coupled plasmonic resonances, also referred to as plasmonic surface lattice resonances (PSLR), are not always compatible with biosensing arrangement implying the placement of the nanoparticles between a glass substrate and a sample medium (air, water)...
December 9, 2017: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/29328332/wavelength-tuning-of-surface-plasmon-coupled-quantum-well-infrared-photodetectors
#3
Wei-Cheng Hsu, Hong-Shi Ling, Shiang-Yu Wang, Chien-Ping Lee
A novel method of detection wavelength tuning for surface plasmon coupled quantum well infrared photodetectors (QWIPs) was demonstrated. By changing of the thickness of the top contact layer, the detection wavelength can be adjusted. The displacement of the detection wavelength is related to the effective dielectric constant of the dielectric layers in the device structure. The peak wavelength moves toward longer wavelength as the contact layer thickness decreases. With a proper match of the 2D metal hole array and the QW absorption region, the responsivity can be kept within a reasonable range for samples with different top contact layer thicknesses...
January 8, 2018: Optics Express
https://www.readbyqxmd.com/read/29328309/role-of-interactions-in-the-magneto-plasmonic-response-at-the-geometrical-threshold-of-surface-continuity-publisher-s-note
#4
Evangelos Th Papaioannou, Hui Fang, Blanca Caballero, Eser Metin Akinoglu, Michael Giersig, Antonio García-Martin, Paul Fumagalli
This publisher's note amends the author listing of [Opt. Express26, 32792 (2017)].
January 8, 2018: Optics Express
https://www.readbyqxmd.com/read/29328284/improving-the-performance-of-hollow-fiber-surface-plasssmon-resonance-sensor-with-one-dimensional-photonic-crystal-structure
#5
Xian Zhang, Xiao-Song Zhu, Yi-Wei Shi
A high performance hollow fiber (HF) surface plasmon resonance (SPR) sensor utilizing one-dimensional photonic crystal (1DPC) is proposed. The performance of the designed sensor is analyzed theoretically with respect to the center wavelength and the bilayer period. Because the light transmitted in the sensor mostly have large incident angles, the center wavelength of the 1DPC should shift to longer wavelength to ensure the band gap covers the spectrum range of the incident light. The sensor exhibits better performance when the detection spectral range is located in the band gap of 1DPC for incident angle larger than 80°...
January 8, 2018: Optics Express
https://www.readbyqxmd.com/read/29328281/thermally-sensitive-scattering-of-terahertz-waves-by-coated-cylinders-for-tunable-invisibility-and-masking
#6
Andriy E Serebryannikov, Kamil B Alici, Ekmel Ozbay, Akhlesh Lakhtakia
Temperature-sensitive scattering of terahertz (THz) waves by infinitely long, cylindrical core-shell structures was theoretically studied. Each structure is a dielectric cylinder coated with an InSb shell illuminated by either a transverse-electric (TE) or a transverse-magnetic (TM) plane wave. InSb is a thermally tunable semiconductor showing a transition from dielectric to plasmonic state at THz frequencies. Accordingly, the total scattering efficiency (TSE) can be thermally tuned for both polarization states of the incident plane wave...
January 8, 2018: Optics Express
https://www.readbyqxmd.com/read/29328275/fabricated-nanogap-rich-plasmonic-nanostructures-through-an-optothermal-surface-bubble-in-a-droplet
#7
Farzia Karim, Erick S Vasquez, Chenglong Zhao
A rapid and cost-effective method for the fabrication of nanogap-rich structures is demonstrated in this Letter. The method utilizes the Marangoni convection around an optothermal surface bubble inside a liquid droplet with a nanoliter volume. The liquid droplet containing metallic nanoparticles reduces the sample consumption and confines the liquid flow. The optothermal surface bubble creates a strong convective flow that allows for the rapid deposition of the metallic nanoparticles to form nanogap-rich structures on any substrate under ambient conditions...
January 15, 2018: Optics Letters
https://www.readbyqxmd.com/read/29328229/two-mode-surface-plasmon-lasing-in-hexagonal-arrays
#8
V T Tenner, M J A de Dood, M P van Exter
We demonstrate surface-plasmon lasing in hexagonal metal hole arrays with a semiconductor gain medium. The device can be tuned between two laser modes, with distinct wavelengths, spatial distributions, and polarization patterns, by changing the size of the optically pumped area. One of the modes exhibits a six-fold polarization pattern, while the mode observed for larger pump spots has a rotationally symmetric polarization pattern. We explain the mode tuning by the differences of in-plane and radiative out-of-plane losses of the modes...
January 15, 2018: Optics Letters
https://www.readbyqxmd.com/read/29328221/localized-excitation-of-polarized-light-emission-by-cathodoluminescence-spectroscopy
#9
Yuhui Hu, Fei Chen, Yajun Gao, Xiang Xiong, Ruwen Peng, Mu Wang
Surface plasmons (SPs), the resonance of free electrons on the metal-air interface, may strongly interact with light and generate some extraordinary optical effects. Instead of using conventional planar light excitation, here we excite SPs with a focused electron beam on metallic nanostructures with different geometrical symmetries. With the help of a polarizer and filter in the detection system, we obtain cathodoluminescence (CL) images with different polarizations at certain wavelengths. The maxima in the CL images show that the focused electron beam may efficiently excite luminescence with different polarizations at different spots...
January 1, 2018: Optics Letters
https://www.readbyqxmd.com/read/29328195/geometrical-optimization-of-nanostrips-for-surface-plasmon-excitation-an-analytical-approach
#10
Thomas Grosges, Dominique Barchiesi
We give a simple tool for the optimization of the dimensions of a metallic nanostrip illuminated at a given wavelength under normal incidence, to get a maximum of the electromagnetic field amplitude in the nanostrip. We propose an analytical formula that gives the widths and heights of the series of nanostrips that produce field enhancement. The validity of the analytical formula is checked by using the finite element method. This design of a nanostrip could be useful for sensors and thermally active components...
January 1, 2018: Optics Letters
https://www.readbyqxmd.com/read/29328194/subwavelength-wave-manipulation-in-a-thin-surface-wave-bandgap-crystal
#11
Zhen Gao, Zhuoyuan Wang, Baile Zhang
It has been recently reported that the unit cell of wire media metamaterials can be tailored locally to shape the flow of electromagnetic waves at deep-subwavelength scales [Nat. Phys.9, 55 (2013)NPAHAX1745-247310.1038/nphys2480]. However, such bulk structures have a thickness of at least the order of wavelength, thus hindering their applications in the on-chip compact plasmonic integrated circuits. Here, based upon a Sievenpiper "mushroom" array [IEEE Trans. Microwave Theory Tech.47, 2059 (1999)IETMAB0018-948010...
January 1, 2018: Optics Letters
https://www.readbyqxmd.com/read/29328189/massive-ordering-and-alignment-of-cylindrical-micro-objects-by-photovoltaic-optoelectronic-tweezers
#12
Iris Elvira, Juan F Muñoz-Martínez, Álvaro Barroso, Cornelia Denz, José B Ramiro, Angel García-Cabañes, Fernando Agulló-López, Mercedes Carrascosa
Optical tools for manipulation and trapping of micro- and nano-objects are a fundamental issue for many applications in nano- and biotechnology. This work reports on the use of one such method, known as photovoltaic optoelectronics tweezers, to orientate and organize cylindrical microcrystals, specifically elongated zeolite L, on the surface of Fe-doped LiNbO3 crystal plates. Patterns of aligned zeolites have been achieved through the forces and torques generated by the bulk photovoltaic effect. The alignment patterns with zeolites parallel or perpendicular to the substrate surface are highly dependent on the features of light distribution and crystal configuration...
January 1, 2018: Optics Letters
https://www.readbyqxmd.com/read/29328188/plasmon-mediated-inverse-faraday-effect-in-a-graphene-dielectric-metal-structure
#13
Igor V Bychkov, Dmitry A Kuzmin, Valentine A Tolkachev, Pavel S Plaksin, Vladimir G Shavrov
This Letter shows the features of inverse Faraday effect (IFE) in a graphene-dielectric-metal (GDM) structure. The constants of propagation and attenuation of the surface plasmon-polariton modes are calculated. The effective magnetic field induced by surface plasmon modes in the dielectric due to the IFE is estimated to reach above 1 tesla. The possibility to control the distribution of the magnetic field by chemical potential of graphene is shown. The concept of strain-driven control of the IFE in the structure has been proposed and investigated...
January 1, 2018: Optics Letters
https://www.readbyqxmd.com/read/29328170/highly-directive-plasmonic-structure-with-double-resonance-at-excitation-and-emission-for-molecule-enhanced-fluorescence
#14
Fangzhou Wang, Guoguo Kang
An improved bull's eye nanostructure is proposed as a substrate for surface-enhanced fluorescence. Optimized by finite-difference time-domain, annular corrugation on both upper and lower surfaces is placed around a nanobow tie in the middle. The whole structure is designed for the excitation and emission process of a certain fluorescence simultaneously, which can enhance the fluorescence intensity enormously (35 times for an excitation field and 120 times for radiation, independently). Meanwhile, it is able to confine the far-field emission energy within a divergence angle of ±3...
January 10, 2018: Applied Optics
https://www.readbyqxmd.com/read/29328076/analysis-of-3d-plasmonic-circuits-by-using-surface-impedance-models
#15
Hoda Ameri, Reza Faraji-Dana
Novel and accurate global and local surface impedance models have been developed to analyze plasmonic circuits fast and efficiently. In the analysis procedure, first the metal strip in the plasmonic circuit is modeled by a surface impedance. Then, the calculated surface impedance is employed in the surface integral equation to analyze the plasmonic circuit such as a through line and line coupler. Accuracy of the numerical results is shown in comparison with a commercial simulation software. The number of unknowns as well as the computational time are also compared with the volume integral equation, and it is obvious that, using our proposed surface impedance models, the analysis will be much faster and more efficient...
January 1, 2018: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
https://www.readbyqxmd.com/read/29327757/rapid-and-sensitive-detection-of-neuron-specific-enolase-with-a-polydopamine-coated-plasmonic-chip-utilizing-a-rear-side-coupling-method
#16
M Toma, S Izumi, K Tawa
A rapid and sensitive detection of a cancer marker, neuron specific enolase (NSE), is demonstrated by using a disposable silver plasmonic chip functionalized with a mussel-inspired polydopamine (PDA) coating. A plasmonic chip consisting of a diffraction grating coated with a silver thin film is used for the excitation of propagating surface plasmon resonance through a rear-side grating coupling method. Simple and quick bio-functionalization of the sensor surface is performed by PDA coating which requires 20 min for deposition, and allows direct attachment of the capture antibody without using any coupling agents...
January 12, 2018: Analyst
https://www.readbyqxmd.com/read/29327590/a-simple-strategy-for-rapid-and-sensitive-detection-of-avian-influenza-a-h7n9-virus-based-on-intensity-modulated-spr-biosensor-and-new-generated-antibody
#17
Ying-Feng Chang, Wen-Hung Wang, Yi-Wei Hong, Ruei-Yu Yuan, Kuan-Hsuan Chen, Yu-Wen Huang, Po-Liang Lu, Yen-Hsu Chen, Yi-Ming Arthur Chen, Li-Chen Su, Sheng-Fan Wang
A new reassortant avian influenza A H7N9 virus have emerged in China since 2013, causing human infection with high mortality. An accurate and timely diagnosis is crucial for controlling the outbreaks of the disease. We therefore propose a simple strategy for rapidly and sensitively detecting the H7N9 virus using an intensity-modulated surface plasmon resonance (IM-SPR) biosensor integrated with a new generated monoclonal antibody. The novel antibody exhibits significant specificity to recognize H7N9 virus compared with other clinical human influenza isolates (p<0...
January 12, 2018: Analytical Chemistry
https://www.readbyqxmd.com/read/29327486/ir-driven-ultrafast-transfer-of-plasmonic-hot-electrons-in-nonmetallic-branched-heterostructures-for-enhanced-h2-generation
#18
Zhenyi Zhang, Xiaoyi Jiang, Benkang Liu, Lijiao Guo, Na Lu, Li Wang, Jindou Huang, Kuichao Liu, Bin Dong
The ultrafast transfer of plasmon-induced hot electrons is considered an effective kinetics process to enhance the photoconversion efficiencies of semiconductors through strong localized surface plasmon resonance (LSPR) of plasmonic nanostructures. Although this classical sensitization approach is widely used in noble-metal-semiconductor systems, it remains unclear in nonmetallic plasmonic heterostructures. Here, by combining ultrafast transient absorption spectroscopy with theoretical simulations, IR-driven transfer of plasmon-induced hot electron in a nonmetallic branched heterostructure is demonstrated, which is fabricated through solvothermal growth of plasmonic W18 O49 nanowires (as branches) onto TiO2 electrospun nanofibers (as backbones)...
January 12, 2018: Advanced Materials
https://www.readbyqxmd.com/read/29324815/biophysical-insights-from-a-single-chain-camelid-antibody-directed-against-the-disrupted-in-schizophrenia-1-protein
#19
Antony S K Yerabham, Andreas Müller-Schiffmann, Tamar Ziehm, Andreas Stadler, Sabrina Köber, Xela Indurkhya, Rita Marreiros, Svenja V Trossbach, Nicholas J Bradshaw, Ingrid Prikulis, Dieter Willbold, Oliver H Weiergräber, Carsten Korth
Accumulating evidence suggests an important role for the Disrupted-in-Schizophrenia 1 (DISC1) protein in neurodevelopment and chronic mental illness. In particular, the C-terminal 300 amino acids of DISC1 have been found to mediate important protein-protein interactions and to harbor functionally important phosphorylation sites and disease-associated polymorphisms. However, long disordered regions and oligomer-forming subdomains have so far impeded structural analysis. VHH domains derived from camelid heavy chain only antibodies are minimal antigen binding modules with appreciable solubility and stability, which makes them well suited for the stabilizing proteins prior to structural investigation...
2018: PloS One
https://www.readbyqxmd.com/read/29324685/novel-spectroscopic-and-electrochemical-sensors-and-nanoprobes-for-the-characterization-of-food-and-biological-antioxidants
#20
REVIEW
Reşat Apak, Sema Demirci Çekiç, Ayşem Üzer, Saliha Esin Çelik, Mustafa Bener, Burcu Bekdeşer, Ziya Can, Şener Sağlam, Ayşe Nur Önem, Erol Erçağ
Since an unbalanced excess of reactive oxygen/nitrogen species (ROS/RNS) causes various diseases, determination of antioxidants that can counter oxidative stress is important in food and biological analyses. Optical/electrochemical nanosensors have attracted attention in antioxidant activity (AOA) assessment because of their increased sensitivity and selectivity. Optical sensors offer advantages such as low cost, flexibility, remote control, speed, miniaturization and on-site/in situ analysis. Electrochemical sensors using noble metal nanoparticles on modified electrodes better catalyze bioelectrochemical reactions...
January 11, 2018: Sensors
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