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109 records returned

A Simple and Rapid Resonance Scattering Spectral Method for Detection of Trace Hg2+ Using Aptamer-Nanogold as ProbeEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract Single-strand deoxyribonucleic acid (ssDNA) were used to modified nanogold particle to obtain a aptamer-nanogold probe (NGssDNA) for Hg(II). The probe is not aggregated in high concentration of NaCl. In the pH 7.0 Na2HPO4-NaH2PO4 buffer solution and in the presence of high concentration of NaCl, NGssDNA interact with Hg(II) to form stable double-strand T-Hg(II)-T mismatches and to release nanogold particles from the probe. The released nanogold particles aggregated to form bigger clusters which leaded the resonance scattering (RS) intensity at 540 nm enhanced linearly with the concentration of ...
Source: Plasmonics - October 21, 2009 Category: Biomedical Science Tags: Plasmonics Source Type: journals

A Polarization-Independent SPR Fiber SensorEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract The resonance of surface plasma waves in metallic layers is a strongly polarization-dependent phenomenon by the very nature of the physical effect responsible of that resonance. This implies the necessity of polarization-controlling elements to be added to any operative surface-plasmon-resonance-based sensor. A fully symmetrical, circular-section double deposition of a metallic and a dielectric layer on a uniform-waist tapered optical fiber (SymDL-UWT) permits us to completely eliminate the dependence on polarization of the plasmon excitation, with the corresponding operative advantages and basic th...
Source: Plasmonics - October 21, 2009 Category: Biomedical Science Tags: Plasmonics Source Type: journals

Oligonucleotide-Mediated Au–Ag Core–Shell NanoparticlesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract The bimetallic core–shell nanoparticles show unique plasmonic properties and their preparations and characterizations are currently under investigation. A new type of Au core–Ag shell (Au@Ag) nanoparticles is prepared by sandwiching the chemically attached Raman reporter molecules (RRMs) and a 12-base-long oligonucleotide between the 13 nm average size core-gold nanoparticles (AuNPs) and 9 nm and 21 nm average size of Ag shell. The synthesized Au@Ag nanoparticles are tested for their surface-enhanced Raman scattering (SERS) performance. It is found that the chemical attachment of ...
Source: Plasmonics - October 6, 2009 Category: Biomedical Science Tags: Plasmonics Source Type: journals

Effect of Gold Coating on Sensitivity of Rhombic Silver Nanostructure ArrayEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This study shows that thickness of the gold coating can be varied to tune the sensitivity of the rhombic silver nanostructure array. The Au–Ag nanostructure array is found to possess the maximum refractive index sensitivity of 714 nm/RIU when thickness of gold is 20 nm, thickness of silver is 25 nm, and refractive index of the medium is around 1.35. The condition for achieving the maximum refractive index sensitivity can be used for detecting many species of biomolecules and drugs in the future. Content Type Journal ArticleDOI 10.1007/s11468-009-9106-2Authors Shaoli Zhu, Nanyang Technological Unive...
Source: Plasmonics - September 29, 2009 Category: Biomedical Science Tags: Plasmonics Source Type: journals

Near-Infrared Metal-Enhanced Fluorescence Using a Liquid–Liquid Droplet Micromixer in a Disposable Poly(Methyl Methacrylate) MicrochipEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract Solution-based metal-enhanced fluorescence of near-infrared fluorophores in a poly(methyl methacrylate) microchip is studied. A liquid–liquid droplet micromixer is used for rapid mixing of fluorophores with silver nanoparticles while maintaining discrete packets of known analytes for reproducible quantitative analysis. Nanoparticle aggregation within the microchip is controlled by individually adjusting salt concentration, colloid concentration, and mixing efficiency. Results identify an optimal salt concentration for aggregate formation and enhanced fluorescence, while the impacts of colloid conc...
Source: Plasmonics - September 23, 2009 Category: Biomedical Science Tags: Plasmonics Source Type: journals

Theoretical and Experimental Investigation of Enhanced Transmission Through Periodic Metal Nanoslits for Sensing in Water EnvironmentEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract Experimental and theoretical study of sensors based on enhanced transmission through periodic metal nanoslits is presented. Our approach consists of the design of one-dimensional nanoslits array and its application in sensing for water quality control. Rigorous coupled waves analysis was used for the design and fit to the experimental data. Two types of surface plasmon resonance excitations are shown to be possible, one at the upper grating–analyte interface and one at the lower grating–substrate interface. This latter resonance is shown to be affected by the multiple interference or cavity-type...
Source: Plasmonics - September 17, 2009 Category: Biomedical Science Tags: Plasmonics Source Type: journals

Wavelength-Ratiometric Plasmon Light Scattering-Based ImmunoassaysEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract The application of a wavelength-ratiometric plasmon light scattering technique to immunoassays is demonstrated. A model immunoassay for anti-immunoglobulin G (IgG), constructed in gold colloid-modified high-throughput screening wells, was monitored by the changes in the intensity of scattered light (with transmitted light) from gold colloids as a result of antibody–antibody interactions. The quantitative determination of anti-IgG was undertaken by measuring the ratio of intensity of scattered light at both 590 and 500 nm. A white light-emitting diode (LED) and a fiber optic coupled fluoromete...
Source: Plasmonics - September 15, 2009 Category: Biomedical Science Tags: Plasmonics Source Type: journals

Synthesis, Conforming, Linear, and Non-linear Optical Properties of Gold Nanoparticles-sepiolite CompactsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract Gold monodispersed nanoparticles (smaller than 10 nm) have been embedded into sepiolite fibres and sintered by spark plasma sintering (SPS) in order to preserve their nanometre size. The optical properties of these nanoparticles have been measured showing the surface plasmon resonance. Plasmon absorption curves have been successfully fitted by using the quasistatic approximation for gold nanoparticles. It has been observed that the sintering process decreases the plasmon width. SPS sintered nanostructured compacts present large values of the non-linear third-order dielectric susceptibility rela...
Source: Plasmonics - August 14, 2009 Category: Biomedical Science Tags: Plasmonics Source Type: journals

Surface Plasmon Effects Excited by the Dielectric Hole in a Silver-Shell Nanospherical PairEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract Using the finite-element method, the surface plasmon effects in a three-dimensional silver-shell nanospherical pair with five different dielectric holes (DHs) that interact with a transverse magnetic mode incident plane wave are investigated. The proposed structure exhibits a red-shifted localized surface plasmon that can be tuned over an extended wavelength range by varying the dielectric constant and the radii in DHs. The increase in the near-field intensity is attributed to a larger effective size of DH that is filled with a higher refractive index medium. The predictive character of these calcul...
Source: Plasmonics - July 27, 2009 Category: Biomedical Science Tags: Plasmonics Source Type: journals

Clustering of Silver Nanoclusters Embedded in Soda Lime Glasses Using Ionic Exchange and Helium Ion BombardmentEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract Silver nanocluster precipitation in AR Schott glass by subsequently silver ionic exchange and helium bombardment was investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV-visible optical absorption. Helium ion bombardment was used to induce local defects in the matrix and to promote the growth of the silver nano-aggregates. The typical implantation depth was estimated at 1 μm by Trim simulation. SEM investigations give us the concentration profile of the exchanged samples and the maximum depth. Optical absorption was performed to visualize the effec...
Source: Plasmonics - July 18, 2009 Category: Biomedical Science Tags: Plasmonics Source Type: journals

An Annular Plasmonic Lens Under Illumination of Circularly Polarized LightEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract In this paper, we consider a circular central aperture surrounded with annular depth-tuned grooves and investigate the beaming effect of the structure under illumination of a circularly polarized (CP) plane wave. As a CP plane wave is equivalent to the superposition of two linearly polarized plane waves (TM and TE) with a phase difference of π/2, the superposition of the electric field intensity, ( | Ex |2 + | Ey |2 ) , is observed in the transmission field. In addition, two plasmonic modes are found at the resonant wavelengths λ 1 and λ 2 with each consisting of multiple wavelengths. At the...
Source: Plasmonics - July 9, 2009 Category: Biomedical Science Tags: Plasmonics Source Type: journals

Tuning Optical Discs for Plasmonic ApplicationsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We present simple physical and chemical procedures that allow tuning and modification of the topography of gratings present in optical storage discs into geometries optimal for grating coupled plasmon resonance excitation. After proper metal coating, the tuned surfaces exhibit sharp plasmon resonances that can be excited at wavelengths ranging from 260 nm to over 2.7 μm with relatively high quality factors. As an immediate exemplary application, use of such optimized gratings in aqueous medium for refractive index measurement is demonstrated. Content Type Journal ArticleDOI 10.1007/s11468-009-9099-xAuthor...
Source: Plasmonics - July 6, 2009 Category: Biomedical Science Tags: Plasmonics Source Type: journals

Polarization-Dependent Confocal Imaging of Individual Ag Nanorods and NanoparticlesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract Polarization-dependent inelastic optical scattering (IOS) of individual Ag nanorods and nanoparticles are studied by confocal imaging. Stronger IOS is observed at two ends of the nanorod with laser polarizing parallel to the rod long axis while the IOS images of Ag nanoparticles elongate along laser polarization direction. The correlation between the far-field IOS image and near-field spatial distributions of the nanostructures′ electric field can be obtained. The IOS imaging is demonstrated to be an effective technique to study the optical properties of metal nanostructures, which also provides i...
Source: Plasmonics - June 12, 2009 Category: Biomedical Science Tags: Plasmonics Source Type: journals

On the Surface Plasmon Resonance Modes of Metal Nanoparticle Chains and ArraysEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract A method for estimating the surface plasmon resonance modes of metal nanoparticle chains and arrays within a multilayered medium is proposed. In this fully retarded point-dipole method, an inhomogeneous background is replaced with a homogeneous one, based on an effective refractive index approximation. The proposed method includes the effects of retardation, radiative damping, and dynamic depolarization due to the finite size of the nanoparticles. The use of diagonal terms of dyadic Green’s functions and different polarizability coefficients along the semi-axes of ellipsoidal nanoparticles provide...
Source: Plasmonics - June 9, 2009 Category: Biomedical Science Tags: Plasmonics Source Type: journals

Optical Biochip with Multichannels for Detecting Biotin–Streptavidin Based on Localized Surface Plasmon ResonanceEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract A rapid and accurate detection of molecular binding of antigen-antibody signaling in high throughput is of great importance for biosensing technology. We proposed a novel optical biochip with multichannels for the purpose of detection of biotin–streptavidin on the basis of localized surface plasmon resonance. The optical biochip was fabricated using photolithography to form the microarrays functioning with multichannels on glass substrate. There are different nanostructures in each microarray. Dry etching and nanosphere lithography techniques were applied to fabricate Ag nanostructures such as hem...
Source: Plasmonics - May 27, 2009 Category: Biomedical Science Tags: Plasmonics Source Type: journals

Gold Nanoparticle Ring and Hole Structures for Sensing Proteins and Antigen–Antibody InteractionsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract A new experimentally simple nanosphere lithography method was used to fabricate gold ring and nanohole structures. The method is based on the simultaneous self-assembly of polystyrene microspheres and gold colloids in multilayers, by a vertical deposition method. Dissolution of polystyrene microspheres resulted in the formation of a monolayer, where holes are surrounded by gold nanoparticles. The dependency of the sensitivity of the sensor platform on the size of the holes and their density has been demonstrated. Furthermore, sensing experiments have shown a high sensitivity of the hole structure to...
Source: Plasmonics - May 21, 2009 Category: Biomedical Science Tags: Plasmonics Source Type: journals

Role of Local Plasmons in Interaction of Light with 1D Periodic Ensembles of Metallic NanowiresEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract The light propagation through 1D metallic nanowires in strong light–matter interaction regimes have been analyzed theoretically. The theoretical calculations are based on differential formalism using curvilinear coordinate transformation and Fourier modal methods, and its comparison in the case of nanowires with rectangular cross section was performed. The transformation of local plasmon into surface plasmon polariton at an increasing metal filling factor while changing the width of rectangular nanowires was predicted theoretically. The essential enhancement of local plasmon oscillator strength at...
Source: Plasmonics - April 16, 2009 Category: Biomedical Science Tags: Plasmonics Source Type: journals

SERS Study of Tetrodotoxin (TTX) by Using Silver Nanoparticle ArraysEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract The optical properties of tetrodotoxin (TTX), a scarce toxin with anesthetic properties, were studied using nanoparticle arrays-assisted surface-enhanced Raman scattering (SERS). The nanoparticles arrays were fabricated using nanosphere lithography and a metallic lift-off process to control the particle size, shape, and spacing in the arrays. Using density functional methods, the Raman spectrum of TTX was also calculated with Gaussian03 software. The main peaks of the spectrum are originated from the vibration of the NH2 molecule group. In the SERS experiment, we were able to measure the Raman spect...
Source: Plasmonics - April 2, 2009 Category: Biomedical Science Tags: Plasmonics Source Type: journals

Silver Fused Conducting Fiber Formation of Au–Ag Core-Shell Nanoparticles Mediated by Ascorbic AcidEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract In this paper, we report the spontaneous formation of fibrous structures consisting of assemblies of Au–Ag core-shell nanoparticles (NPs) from a solution consisting of Au–Ag core-shell NPs and l-ascorbic acid (AA). AA acted both as the reducing agent for the generation of NPs and also as the mediator for the formation of fibers. The process of fiber formation involved three steps—reduction of HAuCl4 to Au NPs by AA, subsequent formation of Au–Ag core-shell NPs after addition of AgNO3, and spontaneous formation of fibers from the mixtures in water. It took typically about 30 days to form c...
Source: Plasmonics - March 25, 2009 Category: Biomedical Science Tags: Plasmonics Source Type: journals

Shape-Controlled Synthesis of Silver Nanoparticles for Plasmonic and Sensing ApplicationsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract The localized surface plasmon resonance of a silver nanoparticle is responsible for its ability to strongly absorb and scatter light at specific wavelengths. The absorption and scattering spectra (i.e., plots of cross sections as a function of wavelength) of a particle can be predicted using Mie theory (for a spherical particle) or the discrete dipole approximation method (for particles in arbitrary shapes). In this review, we briefly discuss the calculated spectra for silver nanoparticles with different shapes and the synthetic methods available to produce these nanoparticles. As validated in recen...
Source: Plasmonics - March 20, 2009 Category: Biomedical Science Tags: Plasmonics Source Type: journals

A Simple and Sensitive SPRS Method for Trace H2O2 Based on the TiO2+ Complex and Gold Nanoparticles Aggregation ReactionsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract In the medium of H2SO4 and in the presence of TiO2+, gold nanoparticles in size of 10 nm exhibited a weak surface plasmon resonance scattering (SPRS) peak at 775 nm. Upon addition of trace H2O2, the yellow complex [TiO(H2O2)]2+ formed that cause the gold nanoparticles aggregations to form bigger gold nanoparticle clusters in size of about 900 nm, and the SPRS intensity at 775 nm (I) enhanced greatly. The enhanced intensity ΔI was linear to the H2O2 concentration in the range of 0.025–48.7 μg/mL, with a detection limit of 0.014 μg/mL H2O2. This SPRS method was applied...
Source: Plasmonics - March 17, 2009 Category: Biomedical Science Tags: Plasmonics Source Type: journals

Preparation of Nanostructured Film Arrays for Transmission Localized Surface Plasmon SensingEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This article presents a concise review of preparation methods for transparent nanostructured films, with an emphasis on their current applications in transmission-localized surface plasmon resonance (T-LSPR) sensing. One of the first methods used for the fabrication of transparent nanostructured metal films is a direct vacuum evaporation of thin gold films. Self-induced formations of small gold islands result in transparent nanostructured gold arrays. The most well-established method is a nanosphere lithography developed by Van Duyne. Nanotriangular island arrays with controlled size and optical properties can be fabri...
Source: Plasmonics - March 17, 2009 Category: Biomedical Science Tags: Plasmonics Source Type: journals

Unidirectional Surface Plasmon Polariton Excitation on Single Slit with Oblique Backside IlluminationEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract We have theoretically investigated the unidirectional surface plasmon polariton (SPP) excitation on single slits with oblique backside illumination. An aperture diffraction method is devised, from which the conditions of slit width and beam illumination angle for the unidirectional SPP excitation are formulated analytically. The derived unidirectional conditions are validated with vectorial electromagnetic simulation using the rigorous coupled wave analysis. Content Type Journal ArticleDOI 10.1007/s11468-009-9086-2Authors Hwi Kim, Seoul National University National Creative Research Center for A...
Source: Plasmonics - March 17, 2009 Category: Biomedical Science Tags: Plasmonics Source Type: journals

Influence of Cr Adhesion Layer on Detection of Amyloid-Derived Diffusible Ligands Based on Localized Surface Plasmon ResonanceEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract A Cr adhesion layer inserted between Ag nanoparticles and a glass substrate, for the purpose of improving the adhesion of Ag nanoparticles to glass, was observed to cause an abnormal peak shift of extinction spectra in non-specific reactions. The undesired peak shift misleads molecule detection in non-specific reactions. To solve this issue, a practical technique using n-propyl-trimethoxysilane-based passivation for the detection of amyloid-derived diffusible ligands was investigated as a route to eliminate the abnormal peak shifting observed in the non-specific reactions. To evaluate this passivati...
Source: Plasmonics - March 12, 2009 Category: Biomedical Science Tags: Plasmonics Source Type: journals

Plasmonic Properties of Silver Nanoparticles on Two SubstratesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract In this paper, we examine the plasmonic properties of silver nanoparticles, with an emphasis on the sensitivity of the extinction spectra on the supporting substrate: silica (SiO2) microsphere and indium tin oxide (ITO) coated glass slide, on which silver particles are deposited electroless and electrochemically, respectively. The microstructures and phases of these nanoparticles are characterized by transmission electron microscopy, field emission electron microscopy and X-ray diffraction analysis. The surface plasmon resonance (SPR) properties which are experimentally measured in the ultraviolet-v...
Source: Plasmonics - March 12, 2009 Category: Biomedical Science Tags: Plasmonics Source Type: journals

Surface Plasmon Enhancement of Optical Absorption in Thin-Film Silicon Solar CellsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract Strong electromagnetic field enhancement that occurs under conditions of the surface plasmon excitation in metallic nanoparticles deposited on a semiconductor surface is a very efficient and promising tool for increasing the optical absorption within semiconductor solar cells and, hence, their photocurrent response. The enhancement of the optical absorption in thin-film silicon solar cells via the excitation of localized surface plasmons in spherical silver nanoparticles is investigated. Using the effective medium model, the effect of the nanoparticle size and the surface coverage on that enhancemen...
Source: Plasmonics - March 11, 2009 Category: Biomedical Science Tags: Plasmonics Source Type: journals

Modulation of Main Lobe for Superfocusing Using Subwavelength Metallic HeterostructuresEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract A subwavelength metallic heterostructure is put forth for the purpose of suppressing sidelobes and improving superfocusing at a quasi-far field region. Improvement has been made by means of optimization of the heterostructure composed of structured Au and Ag thin films. By tuning thicknesses of both the structured Au and Ag films, we can modulate propagation distance of the plasmonic lens and beam width of main lobe for the superfocusing. A finite-difference and time-domain (FDTD) algorithm-based computational numerical calculation was carried out for analyzing the focusing performance and tuning ab...
Source: Plasmonics - March 11, 2009 Category: Biomedical Science Tags: Plasmonics Source Type: journals

Magnetic Excitations in Silver Nanocrescents at Visible and Ultraviolet FrequenciesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract We study magnetic excitations at optical frequencies in disordered crescent-form split-ring resonators made of silver. The resonators that are less than 100 nm in diameter are fabricated on a 4 in. quartz wafer by using a simple, fast, and inexpensive fabrication technique. The measured transmission and polarization-rotation spectra of the resonators reveal the excitation of circulating electric currents that give rise to magnetic dipole moments in the structures at visible and ultraviolet light frequencies. These frequencies have higher values than the limiting magnetic-resonance frequenc...
Source: Plasmonics - March 4, 2009 Category: Biomedical Science Tags: Plasmonics Source Type: journals

Surface Plasmon as a Probe of Local Field EnhancementEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract New method of experimental determination of local field enhancement at metal nanoparticles is suggested. It uses surface plasmon as a probe. Alternating-sign shift of surface plasmon resonance in copper nanoparticles incorporated in silica matrix has been observed under irradiation by intense femtosecond laser pulse. The red shift of plasmon observed during the action of pump pulse is interpreted as a result of change of dielectric constant of silica matrix due to optical Kerr effect in electric field of pump pulse enhanced in a vicinity of metal nanoparticles. The field enhancement factor is estima...
Source: Plasmonics - February 28, 2009 Category: Biomedical Science Tags: Plasmonics Source Type: journals

Solution-Deposited Thin Silver Films on Plastic Surfaces for Low-Cost Applications in Plasmon-Coupled Emission SensorsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We report the deposition of highly uniform thin silver films on plastic materials using a wet-chemistry method, suitable for surface plasmon-coupled emission (SPCE). This approach is reproducible for diverse low-cost applications and versatile to generate silver surfaces on various plastics substrates. An oxygen plasma pretreatment of the plastic provides for rapid silvering, leading to a 47-nm-thick continuous film for SPCE applications. The surface smoothness and thickness of the films have been estimated using atomic force microscope. The higher refractive index of polycarbonate, resulted in an SPCE angle of θ F�...
Source: Plasmonics - February 28, 2009 Category: Biomedical Science Tags: Plasmonics Source Type: journals

Preparation of Gold Nanoparticles and their Applications in Anisotropic Nanoparticle Synthesis and BioimagingEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract In this review, we highlight our recent achievements in using colloidal gold nanoparticles as building blocks for fabrication of anisotropic and multicomponent nanoparticles (e.g., nanoshells, semiconductor nanocrystals, and gold nanorods). The tunable optical properties of these nanoparticles are well suited for various biomedical and biophotonic applications. Content Type Journal ArticleDOI 10.1007/s11468-009-9078-2Authors Ken-Tye Yong, State University of New York at Buffalo Institute for Lasers, Photonics and Biophotonics Buffalo NY 14260–4200 USAMark T. Swihart, State University of New Yor...
Source: Plasmonics - February 28, 2009 Category: Biomedical Science Tags: Plasmonics Source Type: journals

Superfocusing and Light Confinement by Surface Plasmon Excitation Through Radially Polarized BeamEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract We theoretically demonstrate the possibility of obtaining nanosources through an original schema based on the generation of the radially polarized surface plasmon mode of a cylindrical metallic tip. This mode has no cutoff radius and can propagate along the tip walls until its nanometric-sized apex. Instead of radiating from the tip end, the guided mode will give rise to a nanospotlight via the well-known antenna effect. 3D calculations demonstrate that both surface plasmon-guided mode and antenna effect are directly involved in the light confinement. Near-field optical microscopy can benefit signif...
Source: Plasmonics - January 10, 2009 Category: Biomedical Science Tags: Plasmonics Source Type: journals

Recent Advances in the Synthesis of Plasmonic Bimetallic NanoparticlesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract The importance of plasmonic nanoparticles in sensor development, imaging, photodiagnostics, and optoelectronics has resulted in a strong interest toward the development of straightforward synthetic methods for their preparation. In this article, we review some of the most significant advances that have been made in the synthesis of plasmonic bimetallic nanoparticles. Approaches to control morphology, with an emphasis on reactions that produce uniform particles with well-defined sizes and shapes and in high yields, are described. In addition, several characterization techniques that have been employe...
Source: Plasmonics - January 10, 2009 Category: Biomedical Science Tags: Plasmonics Source Type: journals

Localization of Near-Field Resonances in Bowtie Antennae: Influence of Adhesion LayersEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract The near-field resonances of gold bowtie antennae are numerically modeled. Besides the short-range surface plasmon polariton (SR-SPP) mode along the main axis of the structure, a coupled SPP mode is also found in the gap region (G-SPP). The influence of adhesion layers is considered, which depends on the refractive index and the absorption of the adhesion material and whether it is continuous or etched. A high refractive index causes the peak of the SR-SPP to red-shift. High absorption quenches the intensity of the SR-SPP. The magnitude of influence depends on the overlap of the adhesion layer with ...
Source: Plasmonics - December 24, 2008 Category: Biomedical Science Tags: Plasmonics Source Type: journals

Van der Waals Forces Between Plasmonic NanoparticlesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract We propose a new approach to calculate van der Waals forces between nanoparticles where the van der Waals energy can be reduced to the energy of localized plasmons in nanoparticles. The general theory is applied to describe the interaction between two metallic nanoparticles and between a nanoparticle and a perfectly conducting plane. Our results could be used to prove experimentally the existence of new, recently predicted type of plasmon oscillation (Klimov and Guzatov, Phys Rev B 75:024303, 2007a; Klimov and Guzatov, Quantum Electron 37:209, 2007b) and to elaborate new control mechanisms for the ad...
Source: Plasmonics - November 28, 2008 Category: Biomedical Science Tags: Plasmonics Source Type: journals

Functionalization of Gold Nanorods Toward Their ApplicationsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract The topics focusing on functionalization of gold nanorods have been reviewed with a view toward their advanced uses. In most cases, as-prepared gold nanorods are hydrophilic and protected by surfactants, since anisotropic growth of gold nanorods by chemical, electrochemical, and photo-induced methods is carried out in aqueous media in the presence of surfactants and additives. Since solvophilicity of gold nanorods predominantly affects on their optical properties, the control of dispersity of gold nanorods in matrices has been performed, without loss of their optical characters, by surface modificat...
Source: Plasmonics - November 12, 2008 Category: Biomedical Science Tags: Plasmonics Source Type: journals

Plasmonics Moves to a New HomeEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Content Type Journal ArticleDOI 10.1007/s11468-008-9072-0Authors Chris D. Geddes, University of Maryland Biotechnology Institute The Institute of Fluorescence, The Columbus Center 701 East Pratt Street Baltimore MD 21202 USA Journal PlasmonicsOnline ISSN 1557-1963Print ISSN 1557-1955 (Source: Plasmonics)
Source: Plasmonics - November 6, 2008 Category: Biomedical Science Tags: Plasmonics Source Type: journals

Dispersion and Damping of Gold Surface PlasmonEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract High-resolution electron energy loss spectroscopy was used to investigate the surface plasmon dispersion in (111)-oriented Au films grown on Cu(111). The measured dispersion of the plasmon mode was positive, as found for Ag. The centroid of the induced charge associated to the plasmon field lies well inside the jellium edge. The damping relation of the Au surface plasmon presented a critical wave vector of 0.11 Å−1. For higher values of the parallel momentum transfer, the line width of Au surface plasmon considerably increased as a consequence of the opening of a new decay channel via single...
Source: Plasmonics - October 10, 2008 Category: Biomedical Science Tags: Plasmonics Source Type: journals

Three-Dimensional Analysis of Scattering Field Interactions and Surface Plasmon Resonance in Coupled Silver NanospheresEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract Scattering field interactions and surface plasmon resonance (SPR) in coupled silver nanospheres are simulated by using the finite-element method, which includes the influences of near-field enhancements of electric field by the particle sizes, separation distances, propagation directions, as well as the polarizations of the incident wave. The proposed structures exhibit a red- and blue-shifted that can be tuned by varying the particle sizes and the separation distances, respectively. Implications for surface-enhance Raman scattering and nano-optics are discussed in three-dimensional models. The evol...
Source: Plasmonics - October 10, 2008 Category: Biomedical Science Tags: Plasmonics Source Type: journals

Optical Saturable Absorption in Gold NanoparticlesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract In this work, we present the experimental study of the nonlinear absorption of gold nanospheres and nanorods in aqueous suspension, using picosecond white-light supercontinuum open-aperture Z-scan. We demonstrate a saturable absorption effect in all particle suspensions at low-pulse energy. In the high-pulse energy regime, the apparent reverse-saturable absorption, observed in gold nanorods, was determined to be induced by photodegradation. Using the Lorentzian deconvolution method for the absorption spectra, we explain the variations on nonlinear optical effects and prove that saturable absorption ...
Source: Plasmonics - October 9, 2008 Category: Biomedical Science Tags: Plasmonics Source Type: journals

Plasmonic Optical Properties and Applications of Metal NanostructuresEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract In this review article, we provide an overview of recent research activities in the study of plasmonic optical properties of metal nanostructures with emphasis on understanding the relation between surface plasmon absorption and structure. Both experimental results and theoretical calculations have indicated that the plasmonic absorption strongly depends on the detailed structure of the nanomaterials. Examples discussed include spherical nanoparticles, nanorods, nanowires, hollow nanospheres, aggregates, and nanocages. Plasmon–phonon coupling measured from dynamic studies as a function of particle...
Source: Plasmonics - September 23, 2008 Category: Biomedical Science Tags: Plasmonics Source Type: journals

Colloidal Synthesis of Plasmonic Metallic NanoparticlesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This article summarizes our work in recent years on the solution synthesis of nanoparticles with tunable optical properties. The systems of interest include zero-dimensional bimetallic Ag–Au nanoparticles with different structures, one-, two-, and three-dimensional anisotropic monometallic Ag or Au nanoparticles. All of these nanosystems were prepared from colloidal synthesis through simple changes in the synthesis conditions. This is a demonstration of the versatility of colloidal synthesis as a convenient scalable technique for tuning the properties of metallic nanoparticles. Content Type Journal ArticleDOI 10....
Source: Plasmonics - September 17, 2008 Category: Biomedical Science Tags: Plasmonics Source Type: journals

Surface Plasmon Resonance-Based Tapered Fiber Optic Sensor: Sensitivity Enhancement by Introducing a Teflon Layer Between Core and Metal LayerEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract Surface plasmon resonance (SPR)-based tapered fiber optic sensor with Teflon as a dielectric sandwiched between metal and tapered fiber core is proposed. The sensitivity of the sensor has been maximized using different combinations of metal and Teflon layer thicknesses for a given taper ratio. The study shows that the sensitivity of the sensor with the introduction of dielectric (Teflon) increases with the increase in the taper ratio. The maximum sensitivity achieved for a given taper ratio is around 15 times higher than the general SPR-based fiber optic sensor. Content Type Journal ArticleDOI 10...
Source: Plasmonics - September 13, 2008 Category: Biomedical Science Tags: Plasmonics Source Type: journals

Features of the Secondary Emission Enhancement Near Plasmonic Gold FilmEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract Plasmonic gold films (PGF) prepared by vacuum deposition of gold onto quartz slides possess unique property to enhance electromagnetic signal in the near field. Spectral tuning of PGF’s plasmon band to resonance with the electronic spectra of adsorbed molecules provides selective enhancement of fluorescence or surface-enhanced Raman scattering in the far field. Plasmon-enhanced fluorescence (PEF) of mitoxantrone (mitox) as a function of the distance between gold surface and adsorbed molecules for different polarization and incidence angle of exciting light is analyzed in this work. Spectrophotomet...
Source: Plasmonics - August 30, 2008 Category: Biomedical Science Tags: Plasmonics Source Type: journals

Comparisons of Surface Plasmon Sensitivities in Periodic Gold NanostructuresEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract The wavelength sensitivities of three kinds of nanostructures (nanoslits, nanoholes, and concentric circles) with various aperture sizes were compared in water environment. These nanostructures were made on a 110-nm-thick gold film with a period of 600 nm. Surface plasmon resonances in these nanostructures produce transmission dips near the phase-matching conditions while peaks at longer wavelengths. The wavelength sensitivities measured at dips are close to theoretical predictions and about 1.5 times larger than those measured at peaks. Such sensitivity difference is attributed to various surf...
Source: Plasmonics - August 30, 2008 Category: Biomedical Science Tags: Plasmonics Source Type: journals

Spatial Coherence Conversion with Surface Plasmons Using a Three-slit InterferometerEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract It has been demonstrated recently that surface plasmons can change the state of coherence of light emanating from a Young’s double-slit interferometer. This suggests the possibility of developing a “coherence-converting” device with a large array of subwavelength holes in a metal plate. We have taken an intermediate approach by considering a three-slit geometry, in which we investigated the effects on the modulation of the spatial coherence when an additional slit is placed between the pair of Young’s slits. Our results show that the amount of modulation (enhancement or suppression) can be i...
Source: Plasmonics - August 21, 2008 Category: Biomedical Science Tags: Plasmonics Source Type: journals

Plasmonics First Impact Factor of 2.765Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Content Type Journal ArticleDOI 10.1007/s11468-008-9061-3Authors Chris D. Geddes, University of Maryland Biotechnology Institute Institute of Fluorescence, Medical Biotechnology Center, N249 725 West Lombard Street Baltimore Maryland 21201 USA Journal PlasmonicsOnline ISSN 1557-1963Print ISSN 1557-1955 (Source: Plasmonics)
Source: Plasmonics - July 22, 2008 Category: Biomedical Science Tags: Plasmonics Source Type: journals

Plasmonic Notch Filter Design Based on Long-range Surface Plasmon Excitation Along Metal GratingEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract A single notch plasmonic spectral filter design using evanescently coupled resonant ultrathin metal grating is numerically studied in this article. Due to excitation and coupling of long range surface plasmon between the metal grating nanowires, a deep and narrow reflection spectrum dip can be obtained. Narrower spectral bandwidth is achieved through decreased damping from the existence of large dielectric gaps between the grating nanowires. This physical explanation is confirmed by the field distribution calculation. As an example, a single notch filter design with full width half maximum band widt...
Source: Plasmonics - July 22, 2008 Category: Biomedical Science Tags: Plasmonics Source Type: journals

A Highly Sensitive Resonance Scattering Assay for Immunoglobulin M Using Ag(I)–Hydroquinone–Immunonanogold Catalytic ReactionEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract Ten-nanometer nanogold showed the strongest catalytic effect on the particle reaction between Ag(I) and hydroquinone to form nanosilver particles that exhibited the strongest resonance scattering (RS) peak at 350 nm. The enhanced RS intensity was linear to the nanogold concentration in the range of 30–5,700 nM Au. The nanogold was used to label goat antihuman immunoglobulin M (GIgM) to obtain an immunonanogold probe (AuGIgM) for immunoglobulin M (IgM). Based on the nanogold-labeled immunoreaction between IgM and AuGIgM, centrifugation, and AuGIgM–Ag(I)–hydroquinone nanocatalytic reac...
Source: Plasmonics - July 17, 2008 Category: Biomedical Science Tags: Plasmonics Source Type: journals

A Review of an Ultrafast and Sensitive Bioassay Platform Technology: Microwave-accelerated Metal-enhanced FluorescenceEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract Since the publication of our first paper on the microwave-accelerated metal-enhanced fluorescence (MAMEF) bioassay platform technology in 2005 (Aslan and Geddes, Anal Chem 77:8057–8067, 2005), we have been repeatedly asked to comment on the advantages of “microwave heating” with plasmonic nanostructures over conventional heating for bioassays by many of our colleagues in the community. We note that one can find a couple of review articles, one by Mingos (Gabriel et al., Chem Soc Rev 27:213–223, 1998) and another by Thostenson and Chou (Manufacturing 30:1055–1071, 1999), summarizing the fund...
Source: Plasmonics - July 17, 2008 Category: Biomedical Science Tags: Plasmonics Source Type: journals