We report a simple label-free localized surface plasmon resonance sensor that uses the multiple resonances of a U-shaped gold nanostructure to differentiat
In this study, a rationally-designed 2,4,6-trinitrotoluene (TNT) binding peptide derived from an amino acid sequence of the complementarity-determining region (CDR) of an anti-TNT monoclonal antibody was used for TNT detection based on a maleimide-functionalized surface plasmon resonance (SPR) sensor. By antigen-docking simulation and screening, the TNT binding candidate peptides were obtained as TNTHCDR1 derived from the heavy chain of CDR1, TNTHCDR2 derived from CDR2, and TNTHCDR3 from CDR3 of an anti-TNT antibody. The binding events between candidate peptides and TNT were evaluated using the SPR sensor by direct determination based on the 3-aminopropyltriethoxysilane (APTES) surface. The TNT binding peptide was directly immobilized on the maleimide-functionalized sensor chip surface from N-γ-maleimidobutyryl-oxysuccinimide ester (GMBS). The results demonstrated that peptide TNTHCDR3 was identified and selected as a TNT binding peptide among the other two candidate peptides. Five kinds of TNT
We have rationally designed two-dimensional Au and Ag hole arrays for high performing surface plasmon resonance (SPR) sensing. The figure-of-merit (FOM), which is defined as sensitivity/linewidth, is found to be highly geometry-dependent. For sensitivity, we find it is equal to the period of array when exciting low order surface plasmon modes at low incident angle. Therefore, increasing period improves sensitivity. On the other hand, narrow linewidth can be obtained from small hole size so that the radiative decay loss is minimized. By using a pair of orthogonally oriented polarizer and analyzer, the signal-to-noise ratio (SNR) can be greatly enhanced due to the elimination of the nonresonant reflection background. As a proof of our strategy, we have obtained FOM larger than 100/RIU and SNR higher than 110 from Au arrays. Our results show the importance of understanding the basic properties of surface plasmon polaritons in order to systematically optimize the performance of the plasmonic system ...
BioAssay record AID 642885 submitted by ChEMBL: Binding affinity to chicken riboflavin binding protein by surface plasmon resonance assay.
The surface plasmon resonance (SPR) phenomenon is utilized in a number of new real time biosensors. In this study, we have used this technique to study interactions between the central complement component C3b and its multiple ligands by using the Biacore equipment. The SPR technique is particularly suitable for analysis of the alternative complement pathway (AP) because the inherent nature of the latter is to amplify deposition of C3b on various surfaces. C3b was coupled onto the sensor surface and the coupling efficiency was compared under various conditions on both polystyrene and carboxymethylated dextran surfaces. After enzymatic C3b coupling or standard amine C3b coupling, we analyzed and compared the binding of four C3b ligands to the surface: factor B, factor H, C5 and the soluble complement receptor 1 (sCR1, CD35). Binding of each ligand to C3b was detected when C3b had been coupled either enzymatically or using the amine coupling, but the half-lives of the interactions were found to ...
0035] Generally stated, the non-limitative illustrative embodiment described hereinafter relates to a high sensitivity plasmonic structure for use in a surface plasmon resonance (SPR) sensor, and a method of fabrication thereof. The plasmonic structure comprises an array of microholes defining triangles of 700 nm, 950 nm and 1.8 μm edge lengths, which transition to propagating SPR with microhole arrays of decreasing size. Such microhole arrays exhibit a short range SPR mode (as measured in the Kretschmann configuration SPR). Triangle arrays of different sizes and aspect ratio generally exhibit two absorption bands and a transmission maximum in the SPR spectrum. The maximum in transmission at approximately λ=600 nm exhibits the best analytical characteristics for triangle arrays. This maximum shifts significantly with increasing refractive index (RI) for the triangles of 950 nm and 1.8 μm edge lengths, with a sensitivity of 1993 and 1038 nm/RI respectively. This high sensitivity is comparable ...
A side-polished multimode fiber sensor based on surface plasmon resonance (SPR) as the transducing element with a halogen light source is proposed. The SPR fiber sensor is side polished until half the core is closed and coated with a 37 nm gold thin film by dc sputtering. The SPR curve on the optical spectrum is described by an optical spectrum analyzer and can sense a range of widths in wavelengths of SPR effects. The measurement system using the halogen light source is constructed for several real-time detections that are carried out for the measurement of the index liquid detections for the sensitivity analysis. The sensing fiber is demonstrated with a series of refractive index (RI) liquids and set for several experiments, including the stability, repeatability, and resolution calibration. The results for the halogen light source with the resolution of the measurement based on wavelength interrogation were ...
1996 (English)In: 3: rd Meeting and Seminar on : Ceramics,Cells and Tissues, (Ed. Ravaglioli,A. and Krajewski,A.). Gruppo editoriale faenza editrice s.p.a., 1996, 171-178 p.Conference paper, Published paper (Other scientific) ...
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TY - JOUR. T1 - Differential roles of ionic, aliphatic, and aromatic residues in membrane - Protein interactions. T2 - A surface plasmon resonance study on phospholipases A2. AU - Stahelin, R. V.. AU - Cho, W.. PY - 2001/4/17. Y1 - 2001/4/17. N2 - The roles of cationic, aliphatic, and aromatic residues in the membrane association and dissociation of five phospholipases A2 (PLA2), including Asp-49 PLA2 from the venom of Agkistodon piscivorus piscivorus, acidic PLA2 from the venom of Naja naja atra, human group IIa and V PLA2s, and the C2 domain of cytosolic PLA2, were determined by surface plasmon resonance analysis. Cationic interfacial binding residues of A. p. piscivorus PLA2 (Lys-10) and human group IIa PLA2 (Arg-7, Lys-10, and Lys-16), which mediate electrostatic interactions with anionic membranes, primarily accelerate the membrane association. In contrast, an aliphatic side chain of the C2 domain of cytosolic PLA2 (Val-97), which penetrates into the hydrophobic core of the membrane and ...
Autor: Kobayashi, K. et al.; Genre: Zeitschriftenartikel; Im Druck veröffentlicht: 2002-08; Titel: Monolayer formation of cytochrome b(562) on gold surfaces and its reconstitution reaction, studied by surface plasmon resonance spectroscopy
TY - JOUR. T1 - Sequential analysis of multiple analytes using a surface plasmon resonance (SPR) biosensor. AU - Chung, J. W.. AU - Bernhardt, R.. AU - Pyun, J. C.. PY - 2006/4/20. Y1 - 2006/4/20. N2 - A sequential analysis method for the analysis of two analytes was developed using a surface plasmon resonance (SPR) biosensor. A sample with both analytes was introduced into the single sensing region and then each analyte was analyzed sequentially. Two detection models were devised for the samples with the following composition: (1) one target analyte resulting in a sensor response without any label and the other analyte with only additional label, (2) both target analytes requiring additional labels for detection. A standard curve for each model was prepared and applied for sequential analysis of anti-bovine serum albumin (anti-BSA) antibodies and horseradish peroxidase (HRP). The errors of the sequential analysis of Models 1 and 2 were found to be less than 6%, and this method was therefore ...
Protein sequence and surface plasmon resonance analysis of the anti-IGFBP7 sdAb 4.43. (A) Protein sequence of anti-IGFBP7 sdAb 4.43; CDR1, CDR2 and CDR3 are und
en] Surface plasmon resonance (SPR)-based biosensors are very powerful tools for the study of biomolecular interactions, chemical detection and immunoassays. This paper reviews the performance of various SPR structures and detection schemes focusing on propagating surface plasmons generated in planar structures. Some aspects of their surface functionalization, the key element which imparts biofunctionality to these structures and hence transforming them into biosensors, will also be discussed accordingly. The ultimate performance of SPR-based biosensors will thus be determined by both their inherent optical performance and suitable surface functionalization. (C) 2011 Elsevier Ltd. All rights reserved ...
TY - JOUR. T1 - Surface plasmon resonance phase imaging measurements of patterned monolayers and DNA adsorption onto microarrays. AU - Halpern, Aaron R.. AU - Chen, Yulin. AU - Corn, Robert M.. AU - Kim, Donghyun. PY - 2011/4/1. Y1 - 2011/4/1. N2 - The optical technique of surface plasmon resonance phase imaging (SPR-PI) is implemented in a linear microarray format for real-time measurements of surface bioaffinity adsorption processes. SPR-PI measures the phase shift of p-polarized light incident at the SPR angle reflected from a gold thin film in an ATR Kretschmann geometry by creating an interference fringe image on the interface with a polarizer-quartz wedge depolarizer combination. The position of the fringe pattern in this image changes upon the adsorption of biomolecules to the gold thin film. By using a linear array of 500 μm biosensor element lines that are perpendicular to the interference fringe image, multiple bioaffinity adsorption measurements can be performed in real time. Two ...
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Bioelectron. 19, 1497-1504. Oh, B. , Chun, B. , Bae, Y. , Lee, W. , and Choi, J. W. (2005). The fabrication of protein chip based on surface plasmon resonance for detection of pathogens. Biosens. Bioelectron. 20, 1847-1850. , and Matsunaga, T. (1999). Electrochemical detection of allergen in small-volume whole blood using an array microelectrode: A simple method for detection of allergic reaction. Biotechnol. Bioeng. 65, 480-484. Okrend, A. J. , Rose, B. , and Lattuda, C. P. (1992). Isolation of Escherichia coli O157:H7 using O157 specific antibody coated beads. Lee, W. , and Choi, J. W. (2005). The fabrication of protein chip based on surface plasmon resonance for detection of pathogens. Biosens. Bioelectron. 20, 1847-1850. , and Matsunaga, T. (1999). Electrochemical detection of allergen in small-volume whole blood using an array microelectrode: A simple method for detection of allergic reaction. Biotechnol. Bioeng. 65, 480-484. Okrend, A. J. , Rose, B. , and Lattuda, C. P. (1992). Isolation ...
An integrated optical waveguide type surface plasmon resonance (SPR) sensor having an optical waveguide with a corresponding SPR sensing area, photodetectors, and wavelength tunable laser or any kind of external tunable laser source/coupler formed on a substrate. In an embodiment, the laser is a wavelength tunable laser and optionally, the integrated device may include a power source on the substrate for providing a electric power to the wavelength tunable laser and the photodetectors, or a circuit for signal processing, or a microfluidic structure for routing a target sample to the SPR sensor area. The microfluidic structure optionally includes a mixer or a reaction chamber for mixing and allowing a physical or chemical reaction to occur, respectively. In an embodiment, plural planar integrated optical waveguide type SPR sensors may be fabricated on a substrate to form an array of SPR sensors.
... (SPR) is created by surface plasmons, coherent electron oscillations existing between any two materials where the real part of the dielectric function changes sign across the interface. SPR technology is based on the electromagnetic field component of incident light penetrating into a surface and it can be used to detect molecular adsorption on surfaces.. Plasmon excitation typically exists in two configurations: the Kretschmann-Raether configuration, where a thin metal film is sandwiched between a dielectric and air, and the incident wave is from the dielectric side; and the Otto configuration, where an air gap exists between the dielectric and the metal. Using COMSOL Multiphysics, the effect of the SPR on the electromagnetic field can be defined, which has allowed for the measurement of surface contaminants and nano-scale photonic devices.. ...
0082] SPRi detection of biomolecular-binding interactions was performed using the SPRi Lab+ apparatus equipped with an 800 nm LED source, CCD camera and a flow cell (GenOptics, France), placed in Memmert Peltier-cooled incubator (Rose Scientific, Canada) for temperature control (for detailed system specifications, see L. Malic, B. Cui, M. Tabrizian, T. Veres, "Nanoimprinted plastic substrates for enhanced surface plasmon resonance imaging detection," Opt. Express, 17, 20386-92 (2009)). The entire biochip surface was imaged during the angular scan, while for each experiment three ˜500 μm diameter spots were selected for the monitoring of the binding interactions with both the probe and the control. For each spot, the reflected intensity was displayed as a function of angle in the plasmon curve diagram. The slope of the plasmon curves was automatically computed to facilitate the selection of the working angle for kinetic analysis, which corresponded to the point of the plasmon curve at which the ...
Shifting of the surface plasmon resonance wavelength induced by the variation of the thickness of insulating spacer between single layer graphene and Au nanoparticles is studied. The system demonstrates a blue-shift of 29 nm as the thickness of the spacer layer increases from 0 to 15 nm. This is due to the electromagnetic coupling between the localized surface plasmons excited in the nanoparticles and the graphene film. The strength of the coupling decays exponentially with a decay length of d/R = 0.36, where d is the spacer layer thickness and R is the diameter of the Au nanoparticles. The result agrees qualitatively well with the plasmon ruler equation. Interestingly, a further increment of the spacer layer thickness induces a red-shift of 17 nm in the resonance wavelength and the shift saturates when the thickness of the spacer layer increases above 20 nm. © 2012 Optical Society of America ...
The development of a novel electrochemically stable host-guest supramolecular complex at a host surface is described. It was constructed by combining a self-assembled monolayer (SAM) of mono-(6-deoxy-6-mercapto)-beta-cyclodextrin (beta CDSH), iron (III) tetra-(N-methyl-4-pyridyl)-porphyrin (FeTMPyP) as the guest-link-molecule and beta-cyclodextrin-functionalized gold nanoparticles (beta CDAuNP). The building process of the layer-by-layer assembly was monitored by surface plasmon resonance spectroscopy (SPR). The binding processes between the host-functionalized gold surface and the linker molecule (FeTMPyP) were verified to be monovalent, and for host-functionalized gold nanoparticles with FeTMPyP, the interaction was determined to be bivalent. Finally, the electrochemical properties of the electroactive supramolecular multivalent film were determined. (C) 2009 Elsevier B.V. All rights reserved ...
Nanoparticles have offered many diverse capabilities in bioanalysis and biotechnological applications, due to the intrinsic properties of nanoparticle that is distinguished from bulk materials. The integration of nanoparticle, which exhibit unique electronic, photonic, and catalytic properties with biomaterial, which display unique recognition, catalytic, and inhibition property yields novel hybrid nanobiomaterial with synergic properties and functions. In this study, gold (Au) nanoparticle-antibody conjugate was applied for the signal enhancement of surface plasmon resonance (SPR). When small molecule is a target for immobilization or detection, the changes in the angle-dependent attenuated total reflectance (ATR) are often small so the use of SPR method is limited for generic application. The specific interaction between target molecules and Au nanoparticleantibody conjugate induce the change of the surface properties such as mass and roughness, which can be represented as the change of plasmon
Pope ME, Soste MV, Eyford BA, Anderson NL, Pearson TW. Anti-peptide antibody screening: selection of high affinity monoclonal reagents by a refined surface plasmon resonance technique. J Immunol Methods. 2009 Feb 28;341(1-2):86-96. Epub 2008 Nov 28. PMID: ...
Pope ME, Soste MV, Eyford BA, Anderson NL, Pearson TW. Anti-peptide antibody screening: selection of high affinity monoclonal reagents by a refined surface plasmon resonance technique. J Immunol Methods. 2009 Feb 28;341(1-2):86-96. Epub 2008 Nov 28. PMID: ...
Surface Plasmon Resonance (SPR) is a powerful label free optical biosensing technology that relies on the measurement of the refractive index or change of mass in close vicinity of the sensor surface. Therefore, there is an experimental limitation in the molecular weight of the molecule that can be detected and consequently small molecules are intrinsically more difficult to detect using SPR. One approach to overcoming this limitation is to first adsorb smaller molecules onto the sensor surface, and to follow this by using their higher molecular weight antibodies counterparts which ensure the specificity (and are easier to detect via SPR due to their higher weight). Although this has been demonstrated with some success, it is not applicable in every case and some biomolecules such as enzyme are still difficult to detect due to their specific reactivity (enzymatic reaction). In this paper, we present a powerful new method that utilises specifically engineered spacers attached on one end to the ...
The human organism employs G protein coupled receptors (GPCRs), cell surface receptors in the plasma membrane, to transmit extracellular signals such as hormones, neurotransmitters, gustatory and olfactory signals into the interior of the cell. Specific binding of these extracellular ligands induces a conformational change in GPCRs, which allows the interaction with heterotrimeric G proteins and the catalysis of GDP/GTP nucleotide exchange in the G protein. The G protein then transmits the signal by protein-protein interaction to intracellular effector proteins. The publications summarized here on the rhodopsin/transducin system of photoreceptor cells, a model system for GPCRs/G proteins, cover three topics: 1. Methodology developments for biophysical monitoring of the interaction between rhodopsin and transducin by light scattering and evanescent field techniques, in particular surface plasmon resonance spectroscopy. 2. Formation of the active conformation of rhodopsin. The temporal sequence of ...
Original Research and Commentary on p28 CDG Therapeutics Lead Agent and Analogs. Binding of Amphipathic Cell Penetrating Peptide p28 to Wild Type and Mutated p53 as studied by Raman, Atomic Force and Surface Plasmon Resonance spectroscopies.. Signorelli S, Santini S, Yamada T, Bizzarri AR, Beattie CW, Cannistraro S.. Biochim Biophys Acta. 2017 Apr;1861(4):910-921.. Phase 1 trial of p28 (NSC745104), a non-HDM2-mediated peptide inhibitor of p53 ubiquitination in pediatric patients with recurrent or progressive central nervous system tumors: A Pediatric Brain Tumor Consortium Study.. Lulla RR, Goldman S, Yamada T, Beattie CW, Bressler L, Pacini M, Pollack IF, Fisher PG, Packer RJ, Dunkel IJ, Dhall G, Wu S, Onar A, Boyett JM, Fouladi M.. Neuro Oncol., 2016 Sep;18(9):1319-25. p28-mediated Activation of p53 in G2/M Phase of the Cell Cycle Enhances the Efficacy of DNA Damaging and Antimitotic Chemotherapy.. Yamada T, Das Gupta TK, Beattie CW.. Cancer Res. 2016 Feb 26; 76(8): 2354-2365. Chirality ...
A surface plasmon resonance (SPR) apparatus was used to investigate blood plasma coagulation in real-time as a function of thromboplastin and heparin concentrations. The physical reason for the SPR signal observed is discussed and 3 different models are proposed. The response curves were analyzed by multivariable curve fitting followed by feature extraction. Interesting parameters of the sigmoid curves were lag time, slope and maximum response. When thromboplastin concentrations were increased, the lag-time decreased and the slope of the curve increased. A prolonged clotting time was followed mostly by increased maximum response, with exception for samples with no or very little thromboplastin added. High heparin concentrations changed the clotting kinetics. As seen from the lag-time vs. slope relation. Atomic force microscopy pictures of sensor surfaces dried after completed clotting, revealed differences in fibrin network structures as a function of thromboplastin concentration, and fiber ...
The CD8 coreceptor of cytotoxic T lymphocytes binds to a conserved region of major histocompatibility complex class I molecules during recognition of peptide-major histocompatibility complex (MHC) class I antigens on the surface of target cells. This event is central to the activation of cytotoxic T lymphocyte (CTL) effector functions. The contribution of the MHC complex class I light chain, beta(2)-microglobulin, to CD8alphaalpha binding is relatively small and is mediated mainly through the lysine residue at position 58. Despite this, using molecular modeling, we predict that its mutation should have a dramatic effect on CD8alphaalpha binding. The predictions are confirmed using surface plasmon resonance binding studies and human CTL activation assays. Surprisingly, the charge-reversing mutation, Lys(58) --| Glu, enhances beta(2)m-MHC class I heavy chain interactions. This mutation also significantly reduces CD8alphaalpha binding and is a potent antagonist of CTL activation. These results suggest a
Objective To identify the epitopes recognized by autoantibodies targeting platelet-derived growth factor receptor α (PDGFRα) in systemic sclerosis (SSc) and develop novel assays for detection of serum anti-PDGFRα autoantibodies. Methods Epstein-Barr virus-immortalized B cells from 1 patient with SSc (designated PAM) were screened for expression of IgG binding to PDGFRα and induction of reactive oxygen species in fibroblasts. The variable regions of anti-PDGFRα IgG were cloned into an IgG expression vector to generate distinct recombinant human monoclonal autoantibodies (mAb), which were characterized by binding and functional assays. The epitopes of anti-PDGFRα recombinant human mAb were defined by molecular docking, surface plasmon resonance binding assays, screening of a conformational peptide library spanning the PDGFRα extracellular domains, and expression analyses of alanine-scanned PDGFRα mutants. Direct or competitive enzyme-linked immunosorbent assays were established to detect ...
Calcium-calmodulin (CaM) binding to the epidermal growth factor receptor (EGFR) has been shown to both inhibit and stimulate receptor activity. CaM binds to the intracellular juxtamembrane (JM) domain (Met645-Phe688) of EGFR. Protein kinase C (PKC) mediated phosphorylation of Thr654 occurs within this domain. CaM binding to the JM domain inhibits PKC phosphorylation and conversely PKC mediated phosphorylation of Thr654 or Glu substitution of Thr654 inhibits CaM binding. A second threonine residue (Thr669) within the JM domain is phosphorylated by the mitogen-activated protein kinase (MAPK). Previous results have shown that CaM interferes with EGFR-induced MAPK activation. If and how phosphorylation of Thr669 affects CaM-EGFR interaction is however not known.In the present study we have used surface plasmon resonance (BIAcore) to study the influence of Thr669 phosphorylation on real time interactions between the intracellular juxtamembrane (JM) domain of EGFR and CaM. The EGFR-JM was expressed as ...
Gelatinase B (MMP-9) and galectin-3 are widely known to participate in tumor cell invasion and metastasis. Glycans derived from MMP-9 expressed in MCF-7 breast cancer and THP-1 myeloid leukemia cells were compared with those from MMP-9 expressed in natural neutrophils. The many O-linked glycans of neutrophil gelatinase B presented a cluster of mainly galactosylated core II structures, 46% of which were ligands for galectin-3; 11% contained two to three N-acetyllactosamine repeating units that are high-affinity ligands for the lectin. The glycan epitopes thus provide MMP-9 with both high-affinity and (presumably) high-avidity interactions with galectin-3. In contrast, the O-glycans released from MMP-9 expressed in MCF-7 and THP-1 cells were predominantly sialylated core I structures. Only 10% of MCF-7 and THP-1 gelatinase B O-glycans were ligands for galectin-3 and contained only a maximum single N-acetyllactosamine repeat. Consistent with the glycan analysis, surface plasmon resonance binding ...
Protein-Flavonoid Interaction Studies by a Taylor Dispersion Surface Plasmon Resonance SPR Technique: A Novel Method to Assess Biomolecular Interactions. . Biblioteca virtual para leer y descargar libros, documentos, trabajos y tesis universitarias en PDF. Material universiario, documentación y tareas realizadas por universitarios en nuestra biblioteca. Para descargar gratis y para leer online.
Several proteins, like transcription factors, bind to certain DNA sequences, thereby regulating biochemical pathways that determine the fate of the corresponding cell. Due to these key positions, it is indispensable to analyze protein-DNA interactions and to identify their mode of action. Surface plasmon resonance is a label-free method that facilitates the elucidation of real-time kinetics of biomolecular interactions. In this article, we focus on this biosensor-based method and provide a detailed guide how SPR can be utilized to study binding of proteins to oligonucleotides. After a description of the physical phenomenon and the instrumental realization including fiber-optic-based SPR and SPR imaging, we will continue with a survey of immobilization methods. Subsequently, we will focus on the optimization of the experiment, expose pitfalls, and introduce how data should be analyzed and published. Finally, we summarize several interesting publications of the last decades dealing with ...
Although it has been revealed that astrocytes, generally known as star-shaped glial cells, play critical roles in the functions of central nervous system, there have been few efforts to directly modul... Tags: intracellular calcium, near infrared, localized surface plasmon resonance, astrocytes, gold nanorods.
Surface plasmon resonance showed papuamide A did not interact with sCD4 and gp120. Graphs show the calculated expected binding response versus the observed bind
TY - JOUR. T1 - Resonance surface plasmon spectroscopy. T2 - Low molecular weight substrate binding to cytochrome P450. AU - Zhao, Jing. AU - Das, Aditi. AU - Zhang, Xiaoyu. AU - Schatz, George C. AU - Sligar, Stephen G.. AU - Van Duyne, Richard P.. PY - 2006/8/30. Y1 - 2006/8/30. N2 - A new detection mechanism has been developed for low molecular weight substrate binding to heme proteins based on resonance localized surface plasmon spectroscopy. Cytochrome P450 has strong electronic transitions in the visible wavelength region. Upon binding of a substrate molecule (e.g., camphor), the absorption band of cytochrome P450 shifts to shorter wavelength. The event of camphor binding to a nanoparticle surface modified with cytochrome P450 protein receptors is monitored using UV-vis spectroscopy. It is observed for the first time that the binding of the substrate molecules to the protein receptor induces a blue-shift in the localized surface plasmon resonance (LSPR) of the nanosensors. The coupling ...
A biosensing technique in which biomolecules capable of binding to specific analytes or ligands are first immobilized on one side of a metallic film. Light is then focused on the opposite side of the film to excite the surface plasmons, that is, the oscillations of free electrons propagating along the films surface. The refractive index of light reflecting off this surface is measured. When the immobilized biomolecules are bound by their ligands, an alteration in surface plasmons on the opposite side of the film is created which is directly proportional to the change in bound, or adsorbed, mass. Binding is measured by changes in the refractive index. The technique is used to study biomolecular interactions, such as antigen-antibody binding ...
Intercellular adhesion is a complex phenomenon central to the development, structure and functioning of all multicellular organisms. Adhesion is mediated by distinct families of cell-adhesion molecules (CAMs), and recent studies have identified key characteristics of CAMs that influence their function. Affinity and kinetic analyses using a novel technique based on surface plasmon resonance have shown that CAM interactions that mediate transient cell adhesion may have surprisingly low affinities and extremely fast dissociation rate constants.
Nano-optics: Basic studies on surface plasmon resonance, Spin-Orbit interaction of light in micro / nano optical systems, Weak measurements in optics, Quantitative polarimetry in nano-plasmonics, Fano resonances in plasmonic nanostructures; Polarization Optics: Basic theoretical and experimental studies on polarization (Mueller matrices, Stokes vectors, Jones matrices) and coherence characteristics of scattered light in random medium. Biophotonics: Develop novel optical & spectroscopic methods for probing biological systems and other complex systems, explore applications in diagnostics and imaging. ...
We present a theoretical model for analyzing the size dependence of the surface plasmon resonance of metallic nanospheres in a range of sizes down to a single nanometer. Within this model, we explicitly show how different microscopic mechanisms, namely quantization due to size (quantum size effect (QSE)) and dynamical surface screening, affect the energy of the surface plasmon. We demonstrate that the latter mechanism, which can move the surface plasma energy both toward the red or the blue, can be comparable to or even stronger than QSE. Thus, depending on material parameters, QSE may only be observed for ultra-small metal nanoparticles much closer to 1 nm in size than to 10 nm. Results presented herein are in quantitative agreement with recent published experimental results for Ag and Au.
In recent times there has been revival of interest in studying the role of surface plasmons in metallic spheres in various linear and nonlinear processes [1] that can take place in molecules adsorbed...
Surface plasmon polaritons are coherent electron oscillations that propagate along an interface between a Drude metal and a dielectric medium. The excitation of polaritons is highly dependent on the dielectric properties of the metal, the thickness of the metal, and the optical properties of the dielectric material. First, plasmonic activity is assessed for several thicknesses of silver and nickel chromium under He-Ne incidence. Relationships between film thickness and metal dielectric function are explored in both cases. To manipulate the plasmonic activity at the silver surfaces, two methods are explored. Silver oxide was grown on the surface of the silver films, and the resulting reflection curves are compared to the curves of the metal silver film alone. Next, a polymer was added to the top of the silver films, and the reflection curves were compared. Poling of the polymer is also discussed and attempted as a means of dynamically modulating the reflection curves. A weak relationship between the
TY - JOUR. T1 - Photoluminescence from donor-acceptor molecular systems via long distance energy transfer mediated by surface plasmons. AU - Shimada, Takayuki. AU - Tomita, Satoshi. AU - Hotta, Shu. AU - Hayashi, Shinji. AU - Yanagi, Hisao. PY - 2009/4/1. Y1 - 2009/4/1. N2 - We have studied the energy transfer from p-sexiphenyl (p-6P) to 5,5′-bis(4-biphenylyl)-2,2′-bithiophene (BP2T) mediated by surface plasmons (SPs) on a thin silver layer sandwiched between two MgF2 spacers. The SP-mediated fluorescence of the BP2T acceptor is observed at the donor-acceptor distance beyond 200 nm, which is much longer than the Förster distance. The photoluminescence of BP2T is maximized at silver thickness of roughly 40 nm, where the silver layer is transformed from segregated nanoparticles into a continuous film, at an MgF2 thickness of 10.5 to 52.5 nm.. AB - We have studied the energy transfer from p-sexiphenyl (p-6P) to 5,5′-bis(4-biphenylyl)-2,2′-bithiophene (BP2T) mediated by surface plasmons ...
!%Plexera LLC%! has launched the PlexArray HT system, a high-throughput, label-free, surface plasmon resonance-based biomolecular interaction detecti
Random metallic films, before the percolation threshold, present a concentration of electromagnetic field at the nm scale, below the diffraction limit [1], These generated hot spots, induce huge enhancement of light-matter coupling and these substrates thus constitute performing systems for enhanced spectroscopies. However, the nature of the plasmon modes is still unclear at the percolation threshold and this manuscript presents experimental and theoretical investigations of these plasmon modes. Films are synthetized by evaporation of silver glass. By varying the effective thickness, one goes from isolated metallic structure to continuous thin film. Then, the nature of the plasmon mode, evolving from Localized Surface Plasmon Resonance (LSPR) to Surface Plasmon Polariton (SPP), is probed by Attenuated Total Reflection measurements (ATR). Our ATR study shows that before the transition to conductive state, in TM excitation, two drastically different behaviors are present at the same wavelength but ...
Alterations in peptide ligand that result in better or worse binding to MHC are effectively a change in concentration of pMHC ligand. This becomes especially significant in in vivo settings, where encounter with Ag is usually more rare. When comparing different peptide ligands, careful determination of MHC binding is obviously essential prior to making conclusions as to the effect of various ligands upon TCR-pMHC interactions.. The rate at which TCR and pMHC associate (kon) and dissociate (koff) is shown. The t1/2 of the TCR-pMHC interaction is related to the off-rate koff by the equation t1/2 = ln 2/koff. Thus, shorter TCR-pMHC interactions have shorter t1/2 and faster off-rates relative to longer TCR-pMHC interactions. In equilibrium conditions, the affinity is calculated from koff/kon, which can be derived from surface plasmon resonance measurements. The t1/2 of TCR-pMHC interactions can also be measured by dissociation of fluorescently labeled pMHC tetramers (11), and the off-rates ...
The study of optical phenomena related to the strong electromagnetic response of noble metals (silver (Ag) and gold (Au) being most popular) over the last couple of decades has led to the emergence of a fast growing research area called plasmonics named after surface plasmons which are electron density waves that propagate along the interface of a metal and a dielectric medium. Surface plasmons are formed by the coupling of light to the electrons on the metal surface subject to the fulfillment of certain physical conditions and they are bound to the metal surface. Depending on whether the metallic medium is a continuous film or a structure having dimensions less than or comparable to the wavelength of the exciting light, propagating or localized surface plasmons can be excited. The structure can be either a hole or an arbitrary pattern in a metal film, or a metallic particle. An array of subwavelength structures can behave as an effective homogeneous medium to incident light and this is the ...
A new branch of fluorescence has emerged with the use of metallic nanostructures to enhance optical signals: Plasmon enhanced fluorescence (PEF). In the literature it has grown with two different names: surface enhanced fluorescence (SEF) and also metal enhanced fluorescence (MEF). In this thesis, we have explored some of the peculiar properties of plasmon enhanced fluorescence. In particular, we try to relate intrinsic molecular properties of fluorescence such as cross section and quantum yield to the enhanced signal. The source and basic properties of localized surface plasmon resonances is also discussed. The attention is then centre in the plasmon signature on the fluorescence spectrum or spectral profile modification. The matching of plasmon scattering and fluorescence emission assists in constructing fluorophore-nanoparticle systems for PEF applications. Specific experiments are discussed design to test the impact of the fluorophore quantum yield in observed enhancement. Finally, a practical