Gain-Assisted Propagation and Angular Response of Surface Plasmon Resonance in Nonlinear Kretschmann Configuration

The present study investigates the optical characteristics and angular response of gain-assisted surface plasmon resonance incorporating a nonlinear Kretschmann configuration. Nonlinear susceptibility of two-level atoms is used to describe the gain and nonlinear characteristics of amplifying medium. The structure is investigated and compared in both linear and nonlinear regimes. Our theory presents surface plasmon polaritons (SPPs) amplification accounting for saturation of linear gain by nonlinear losses. Reflectivity curve of the Kretschamnn configuration, attenuation constant, propagation length, and magnetic field intensity of plasmonic wave at the interface provide direct proofs of saturated gain induced by nonlinear absorption loss. Linear analysis predicts enhanced total reflection (ETR) in the presence of gain while in nonlinear regime, no ETR phenomenon occurs due to nonlinear loss absorption. Our analysis verifies that in the presence of nonlinear absorption loss, a saturation tendency of propagation length and plasmonic intensity is inevitable which is coincident with the practical observations.     

Detect the Hybridization of Single-Stranded DNA by Parallel Scan Spectral Surface Plasmon Resonance Imaging

We investigate the ability of a parallel scan spectral surface plasmon resonance imaging system in analyzing hybridization of single-stranded DNA (ssDNA) on microarray. The ssDNA probes are modified by a thiol group and thereby can be immobilized onto the gold film. Hybridization experiments are carried out by using both complementary and noncomplementary sequence to confirm the specificity of interaction. We also demonstrate that the data analysis is very important in reducing the noise and improving the resolution by comparing polynomial fitting method with the combination of polynomial fitting and centroid method. Finally, the results demonstrate that the parallel scan spectral surface plasmon resonance imaging system can be used for high-throughput analysis of the hybridization of the ssDNA.     

Imaging of Surfaces by Concurrent Surface Plasmon Resonance and Surface Plasmon Resonance-Enhanced Fluorescence

Surface plasmon resonance imaging and surface plasmon induced fluorescent are sensitive tools for surface analysis. However, existing instruments in this area have provided limited capability for concurrent detection, and may be large and expensive. We demonstrate a highly cost-effective system capable of concurrent surface plasmon resonance microscopy (SPRM) and surface plasmon resonance-enhanced fluorescence (SPRF) imaging, allowing for simultaneous monitoring of reflectivity and fluorescence from discrete spatial regions. The instrument allows for high performance imaging and quantitative measurements with surface plasmon resonance, and surface plasmon induced fluorescence, with inexpensive off-the-shelf components.     

A Phase Sensitivity-Enhanced Surface Plasmon Resonance Biosensor Based on ITO-Graphene Hybrid Structure

Plasmonics - In this paper, a surface plasmon resonance (SPR) sensor based on the hybrid structure of silver (Ag)-indium tin oxide (ITO)-graphene is proposed and investigated. SPR biosensors are...     

Surface Plasmon Resonance Imaging Sensors: A Review

Surface plasmon resonance (SPR) imaging sensors realize label-free, real-time, highly sensitive, quantitative, high-throughput biological interaction monitoring and the binding profiles from multi-analytes further provide the binding kinetic parameters between different biomolecules. In the past two decades, SPR imaging sensors found rapid increasing applications in fundamental biological studies, medical diagnostics, drug discovery, food safety, precision measurement, and environmental monitoring. In this paper, we review the recent advances of SPR imaging sensor technology towards high-throughput multi-analyte screening. Finally, we describe our multiplex spectral-phase SPR imaging biosensor for high-throughput biosensing applications.     

Theoretical Differential Phase Analysis for Characterization of Aqueous Solution Using Surface Plasmon Resonance

Surface plasmon resonance (SPR)-based differential phase analysis has been presented. Real as well as complex plane analysis of resonance parameters have been undertaken for the optimum selection of metal thicknesses in a bimetallic SPR configuration working under both angular and spectral regime. Theoretically, we can characterize the aqueous solution in terms of this differential phase variation due to the variation of sample parameters such as concentration and temperature. In this respect, two case studies, namely, concentration of hemoglobin in human blood and sensing of temperature of water have been demonstrated and proposed theoretically. By monitoring the change of differential phase, proposed approach leads to a very sensitive measurement of concentration and temperature.     

Highly Sensitive Surface Plasmon Resonance Biosensors Utilizing Prism-Waveguide Configuration for Detection of Alzheimer Disease Biomarker

Plasmonics - Alzheimer’s disease (AD) is a disease in cognitive regions in the human brain. Also the detection of AD in the early stage is too important. In this regard, a surface plasmon...     

Tunable Properties of Surface Plasmon Resonance of Metal Nanospheroid: Graphene Plasmon Interaction

Plasmonics - Graphene plasmonic resonances play a significant role for enhancing the photon absorption inside thin film solar devices. We investigate the field rising at the intersection of...     

Electrically Control Lateral Shift Owning to Guided-Wave Surface Plasmon Resonance with a Lithium Niobate Prism

Electrically controlled lateral shift by an electro-optic crystal prism is studied theoretically. The resonance point of excitation of guided-wave surface plasmon resonance (GWSPR) can be controlled by altering the refractive index of the prism. That is to say, the positions corresponding to the least reflectivity and the largest lateral shift could be conveniently modulated while the lithium niobate prism is operated in an external electric field. The maximal lateral shift is obtained at the excitation of GWSPR when the thickness of the silver film is optimized. The results of numerical simulations confirm theoretical calculation.

     

Correction to: Liquid Crystal-Based Surface Plasmon Resonance Biosensor

Plasmonics - The article Liquid Crystal-Based Surface Plasmon Resonance Biosensor, written by Ali Vahedi and Mohammad Kouhi, was originally published electronically on the publisher’s...     

Metal-Dielectric-Graphene Hybrid Heterostructures with Enhanced Surface Plasmon Resonance Sensitivity Based on Amplitude and Phase Measurements

Metal-dielectric-graphene hybrid heterostructures based on oxides Al₂O₃, HfO₂, and ZrO₂ as well as on complementary metal–oxide–semiconductor compatible dielectric Si₃N₄ covering plasmonic metals Cu and Ag have been fabricated and studied. We show that the characteristics of these heterostructures are important for surface plasmon resonance biosensing (such as minimum reflectivity, sharp phase changes, resonance full width at half minimum and resonance sensitivity to refractive index unit (RIU) changes) can be significantly improved by adding dielectric/graphene layers. We demonstrate maximum plasmon resonance spectral sensitivity of more than 30,000 nm/RIU for Cu/Al₂O₃ (ZrO₂, Si₃N₄), Ag/Si₃N₄ bilayers and Cu/dielectric/graphene three-layers for near-infrared wavelengths. The sensitivities of the fabricated heterostructures were?~?5–8 times higher than those of bare Cu or Ag thin films. We also found that the width of the plasmon resonance reflectivity curves can be reduced by adding dielectric/graphene layers. An unexpected blueshift of the plasmon resonance spectral position was observed after covering noble metals with high-index dielectric/graphene heterostructures. We suggest that the observed blueshift and a large enhancement of surface plasmon resonance sensitivity in metal-dielectric-graphene hybrid heterostructures are produced by stationary surface dipoles which generate a strong electric field concentrated at the very thin top dielectric/graphene layer.

     

Optimization of Multimode Fibers for Surface Plasmon Resonance Based Sensors Under Spectral and Single Wavelength Intensity Interrogation

Plasmonics - In an optical fiber based SPR sensor, a segment of metal clad silica fiber is used as the sensing element and resonant coupling occurs to the surface plasmon mode excited at the...     

Characterization of Glycoprotein Oligosaccharides Using Surface Plasmon Resonance

Surface plasmon resonance was used to characterize the carbohydrate moieties of bovine fetuin. This technique, requiring no sample derivitization or labeling, identified the presence and composition of both N- and O-linked oligosaccharides, using a combination of lectin probes and in situ glycosidase digestion. A complete analysis was achieved using 1.4 μg of pure bovine fetuin, and was fully automated using Pharmacia′s BIAcore. The presence or absence of specific oligosaccharide structures was determined by the binding of a panel of unlabeled lectins. Monosaccharide order and linkages were determined by sequential digestion using a range of specific exoglycosidases. This novel method implementing in situ digestion was achieved using a modification to the BIAcore software, allowing the flow of reagent over the sensor chip to be stopped for variable lengths of time, thereby permitting enzymatic digestion to occur. This technique can be applied to other commercial SPR biosensors currently available. Glycoanalysis by SPR uses approximately 100- to 1000-fold less protein than comparable analyses using alternative techniques such as gel permeation chromatography of released oligosaccharides, labeled lectin binding, or mass spectrometry.     

Longitudinal Spin Splitting of Vortex Beam in Surface Plasmon Resonance

Plasmonics - The spin-dependent longitudinal splitting of a vortex beam carrying orbital angular momentum is studied in surface plasmon resonance. The existence of orbital angular momentum induces...     

Size and Temperature Effects on the Surface Plasmon Resonance in Silver Nanoparticles

The surface plasmon energy in spherical silver nanoparticles embedded in silica host matrix depends on the size and temperature of the nanoparticles. The dependences of the surface plasmon energy were studied for silver nanoparticles in the size range 11?C30?nm and in the temperature interval 293?C650?K. As the size of the nanoparticles decreases or the temperature increases, the surface plasmon resonance shifts to red. When the size of the nanoparticles decreases, the scattering rate of the conduction electrons increases, which results in the nonlinear red shift of the surface plasmon resonance. The red shift with temperature is linear for larger nanoparticles and becomes nonlinear for smaller ones. As the temperature of the nanoparticles increases, the volume thermal expansion of the nanoparticles leads to the red shift of the surface plasmon resonance. The thermal volume expansion coefficient depends on the size and temperature. It increases with a decrease of the nanoparticle size and an increase of the temperature.     

Surface Plasmon Coupling Effect of Gold Nanoparticles with Different Shape and Size on Conventional Surface Plasmon Resonance Signal

The labeling strategy with gold nanoparticles for the conventional surface plasmon resonance (SPR) signal enhancement has been frequently used for the sensitive determination of small molecules binding to its interaction partners. However, the influence of gold nanoparticles with different size and shape on SPR signal is not known. In this paper, three kinds of gold nanoparticles, namely nanorods, nanospheres, and nanooctahedrons with different size, were prepared and used to investigate their effects on the conventional SPR signal at a fixed excitation wavelength 670 nm. It was found that the SPR signal (i.e., resonant angle shift) was varied with the shapes and sizes of gold nanoparticles in suspension at a fixed concentration due to their different plasmon absorbance bands. For gold nanorods with different longitudinal absorbance bands, three conventional SPR signal regions could be clearly observed when the gold nanorod suspensions were separately introduced onto the SPR sensor chip surface. One region was the longitudinal absorbance bands coinciding with or close to the SPR excitation wavelength that suppressed the SPR angle shift. The second region was the longitudinal absorbance bands at 624 to 639 and 728 to 763 nm that produced a moderate increase on the SPR resonant angle shift. The third region was found for the longitudinal absorbance bands from 700 to 726 nm that resulted in a remarkable increase in the SPR angle shift responses. This phenomenon can be explained on the basis of calculation of the correlation of SPR angle shift response with the gold nanorod longitudinal absorbance bands. For nanospheres and nanooctahedrons, the SPR angle shift responses were found to be particle shape and size dependent in a simple way with a sustaining increase when the sizes of the nanoparticles were increased. Consequently, a guideline for choosing gold nanoparticles as tags is suggested for the SPR determination of small molecules with binding to the immobilized interaction partners.     

Sensitive and Label-Free Detection of DNA by Surface Plasmon Resonance

While an array of technologies based on radioactive labels or luminescent tags are dominant in modern biomedical research on DNA, surface plasmon resonance (SPR) and SPR imaging measurements are sensitive, rapid, and label-free. This review summarizes recent advances in the development of SPR and coupled techniques and their applications in DNA research, including the gene analysis at trace levels and studies of DNA–protein and DNA–drug interactions.     

利用表面等离子体共振仪检测黄瓜花叶病毒

目的：研究一种便捷、高效地检测黄瓜花叶病毒（CMV）的方法。方法：利用表面等离子体共振（SPR）技术检测CMV。首先用11-MUA修饰SPR金片,再用EDC／NHS活化,之后通过NHS酯基与CMV抗体结合,用BSA封闭未结合的NHS酯基。将SPR金片装入SPR仪,通入待检样品,通过折射率变化实时监测实验过程。结果：该方法检测CMV的灵敏度能够达到10ng／mL,具有良好的特异性,与同属的花生矮化病毒、番茄不孕病毒无交叉反应。结论：建立的SPR方法操作简单、灵敏度高、特异性好,是一种新的高效检测CMV的方法。     

偏振干涉角度调制SPR传感技术研究及应用进展

针对一种新兴生物检测方法——表面等离子体波共振(SPR)技术,文中SPR传感系统采用偏振干涉和角度调制方案,使SPR传感灵敏度与光复反射系数的模和相位都相关,从而实现较大线形范围内的高灵敏测量。同时开展了该SPR传感系统在环保领域的应用研究,SPR共振信号可实时随甲烷含量线性改变,气体检测灵敏度达到1 070ppm,实验结果验证了这种SPR传感技术的检测性能并显示了其在环保监测领域的应用潜力。