Basis Of Surface Plasmon Resonance Research Articles

A Polished-D-Shape SPR-Based Photonic Crystal Fiber Sensor with High Sensitivity for Measuring Refractive Index

In the correspondence, a novel polished-D-shape photonic crystal fiber sensor structure on the basis of surface plasmon resonance is proposed for measuring analyte refractive index. With the help of the finite element method, sensing performances of the structure have been analyzed through numerical simulations along with a step-by-step optimization . In this design, different capillaries are gathered and processed to form a D-shape silica structure and nano-scale gold material is coated on the flattened surface. With utilization of a thin gold film and solid silica background, the resonance effect is excited and the loss curve has red shift along with an increase in refractive index, which is applied for sensing. From the simulation and calculation results, the final sensor structure achieves the optimal performance where values of maximum and average sensitivity reach 32,000 and 12,167 nm/RIU along with a sensing coverage of refractive index from 1.26 to 1.32. Also, the proposed design obtains a range of resonant wavelength from 1810 to 2540 nm. We believe the proposed sensor can be a potential candidate for organic and biological detection and related applications.

A Dual-Core Surface Plasmon Resonance-Based Photonic Crystal Fiber Sensor for Simultaneously Measuring the Refractive Index and Temperature

In this correspondence, a new photonic crystal fiber biosensor structure on the basis of surface plasmon resonance is proposed for the measurement of the refractive index (RI) and TSM temperature simultaneously. In this design, the central and external surface of the biosensor structure are coated with thin gold film. A hole adjacent to the inner gold film is filled with temperature-sensitive material (TSM). With the implementation of internal and external gold coatings along with TSM, the biosensor achieves the measurement of the RI and temperature with two disjoint wavelength coverage. Numerical simulations and calculation results illustrate that the average wavelength sensitivity of the biosensor structure, respectively, achieves 7080 nm/RIU and 3.36 nm/°C with RI coverage from 1.36 to 1.41 and temperature coverage from 0 to 60 °C. Moreover, benefiting from realization of different wavelength regions in RI and temperature sensing, it is believed that the proposed biosensor structure for the measurement of the RI and temperature will have range applications in the fields of medical diagnostics and environmental assessments.

Enhanced photocurrent in thin-film GaAs solar cells with embedded Al nanoparticles

ABSTRACTIt is believed that the effectual scattering by earth-abundant Al nanoparticles in combination with photoelectric conversion-efficient GaAs material may help for cost-effective solar cells. Al nanoparticles of various radii embedded at different depths in a Ta2O5-coated GaAs semiconductor have been studied by finite-difference time-domain method for their influence towards spectral absorption rate and photocurrent in GaAs solar cells. The calculated spectral absorption rate and photocurrent show a significant enhancement at the optimal depth for a particular radius of Al nanoparticles, which is explained on the basis of surface plasmon resonance. Al nanoparticles of radius 80 nm embedded just below the antireflection layer of Ta2O5 result a maximum spectral absorption rate of 0.95 that leads to a photocurrent of 30.43 mA/cm2.

Evaluating the Potential of an Antibody Against Recombinant OmpW Antigen in Detection of Vibrio cholerae by Surface Plasmon Resonance (SPR) Biosensor

Surface plasmon resonance (SPR), a highly sensitive and label-free optical biosensing technique, is a powerful tool for studying biomolecular interactions. An immunosensor for rapid, sensitive, and selective detection of Vibrio cholerae on the basis of SPR is reported. Recombinant OmpW antigen (a bacterial outer-membrane protein) of V. cholerae was expressed and purified and raising of polyclonal rabbit anti-OmpW was done. Antibodies were immobilized on a sensor surface and interactions between OmpW protein and the whole cell of V. cholerae with immobilized antibodies were studied in different experiments. The aim of this study was to evaluate the potential of anti-OmpW in detection of V. cholerae by developing an immunosensor based on SPR. The results showed high affinity interaction between OmpW and anti-OmpW (K D = 2.4 ± 0.07 × 10−9 M) and SPR signals had a linear relationship with the number of V. cholerae ranging from 1 × 102 to 1 × 107 cells/mL with limit of detection of 50 cells/mL. The specificity of the developed immunoassay was examined using some non-V. cholerae bacteria which did not produce any significant responses. This method is rapid, sensitive, and specific to target V. cholerae with a total analysis time of less than 60 min.

Thermal-Vision Method of Investigations and Control of Device Based on Surface Plasmon Resonance

As is known, the miniaturization of analytical devices makes them more user-friendly and extends the sphere of their application. At the same time, however, the miniaturization deteriorates temperature schedules of the operation of devices because of localization that entails overheating and thereby making thermal errors of measurements more appreciable. This is especially critical to analytical devices operating on the basis of surface plasmon resonance because in that case a measurable value depends heavily on changes in a temperature. The main purpose of research is to use the method of nondestructive testing so as to analyze the thermal processes that take place in analytical devices operating on the basis of the surface plasmon resonance. This research suggests and shows the efficiency of the application of the thermal-vision method to detect the most heat-generating sources in analytical devices operating on the basis of the surface plasmon resonance. The results of this research can be used to improve the analytical devices as well as to streamline their design and fundamental basis.

Back Cover: Ag/AgBr-Grafted Graphite-like Carbon Nitride with Enhanced Plasmonic Photocatalytic Activity under Visible Light (ChemCatChem 8/2013)

Hybrid heaven The cover picture shows a new plasmonic photocatalytic mechanism of a visible-light-driven plasmonic photocatalyst Ag/AgBr/g-C3N4 (g=graphite-like), proposed on the basis of surface plasmon resonance (SPR) and charge separation of Ag. In their Full Paper on p. 2343 ff., W.-D. Zhang and Y.-S. Xu describe how their metal–semiconductor ternary composite photocatalyst, compared with bare g-C3N4 or Ag/AgBr nanoparticles, shows respective 28- and 6-fold improvements in the degradation rate toward rhodamine B under visible-light irradiation.

Sonochemical synthesis of solar-light-driven Ag̊-PbMoO4 photocatalyst

Ag̊-PbMoO4 photocatalysts were synthesized by facile sonochemical method with different mol.% of Ag nanoparticles dispersed on the surface of PbMoO4. The synthesized powders were characterized by X-ray Diffraction (XRD) Spectroscopy, X-Ray Photoelectron Spectroscopy (XPS), Transmission Electron Microscopy (TEM), and Diffuse Reflectance Spectroscopy (UV–vis DRS) to investigate the crystal structure, morphology, chemical composition, and optical properties of the photocatalyst. Photocatalytic activities of the Ag̊-PbMoO4 samples were evaluated by the degradation of Indigo Carmine (IC) dye under simulated solar light irradiation. It has been observed that the sample containing 0.3mol.% of Ag showed the best photocatalytic activity as compared to other samples. The results suggest that the dispersion of Ag nanoparticles on the surface of PbMoO4 significantly enhances the photocatalytic activity of PbMoO4. Increase in photocatalytic activity of Ag̊-PbMoO4 photocatalyst has been explained on the basis of surface plasmon resonance (SPR) effect caused by the silver nanoparticles present in the photocatalyst.

Block Copolymer Micelles as Nanoreactors for Self-Assembled Morphologies of Gold Nanoparticles

Self-assembled gold (Au) nanoparticles (NPs) were synthesized in micelle surface cavities of a L121 block polymer in the presence of zwitterionic (viz. DPS, TPS, and HPS) and sugar surfactants (OG and DDM) in aqueous phase at 70 °C by using the surface cavities of L121 as reducing sites for converting Au(III) into Au(0). All reactions were monitored simultaneously by UV-visible spectroscopy to determine the growth kinetics in gold nucleating centers on the basis of surface plasmon resonance that also helped in tracing the structure micelle transitions over a wide temperature range of 10-70 °C. The surfactant/L121 mole ratio was changed systematically from 0.5 to 2.5 by keeping L121 and HAuCl4 concentrations constant at 10 and 0.25 mM, respectively, to determine the shape and size of the micelles and their relation to the self-assembled behavior of Au NPs. TEM studies were used to have a direct insight into the morphology of micelle templates and their shape and size for self-assembled NPs. L121 along with DPS (C12 carbon chain) produced well-defined micelles loaded with tiny NPs of 3-6 nm in the L121-rich region of the mixture, while large flower-like compound micelles with a clear core-shell morphology were produced in the DPS-rich region. TPS and HPS (C14 and C16 hydrocarbon chains, respectively) with stronger hydrophobicity than DPS also produced almost similar micelles loaded with tiny NPs in the L121-rich region, but they disappear in the surfactant-rich region. Replacement of zwitterionic with ionic surfactants did not yield micelle templates for self-assembled NPs. Results conclude that well-defined micelles of L121 are the fine templates for self-assembled NPs that can only be achieved in the presence of a neutral surfactant with low concentration and low hydrophobicity.

Microwave assisted hydrothermal synthesis of Ag/AgCl/WO3 photocatalyst and its photocatalytic activity under simulated solar light

Simulated solar light responsive Ag/AgCl/WO3 composite photocatalyst was synthesized by microwave assisted hydrothermal process. The synthesized powders were characterized by X-Ray Diffraction (XRD) spectroscopy, X-Ray Photoelectron Spectroscopy (XPS), Transmission Electron Microscopy (TEM), Diffuse Reflectance Spectroscopy (UV–Vis DRS), and BET surface area analyzer to investigate the crystal structure, morphology, chemical composition, optical properties and surface area of the composite photocatalyst. This photocatalyst exhibited higher photocatalytic activity for the degradation of rhodamine B under simulated solar light irradiation. Dye degradation efficiency of composite photocatalyst was found to be increased significantly as compared to that of the commercial WO3 nanopowder. Increase in photocatalytic activity of the photocatalyst was explained on the basis of surface plasmon resonance (SPR) effect caused by the silver nanoparticles present in the composite photocatalyst.

SPR-based immunosensor for determining staphylococcal enterotoxin A

An immunosensor for determining staphylococcal enterotoxin A (SEA) was developed on the basis of surface plasmon resonance (SPR). The sensor surfaces were constructed from various thiol mixtures of different molar ratios of 16-mercapto-1-hexanol (16-MHA) to 6-mercapto-1-hexanol (6-MCH). The surface functionalized with a 1:20 mixed self-assembled monolayer (SAM) exhibited the best result in terms of SEA detection sensitivity. Through optimization of anti-SEA immobilization, the SPR sensor could detect SEA in phosphate-buffered saline buffer in a linear range from 100 to 1000 ng/ml. Furthermore, studies of recovery and matrix effects were performed to evaluate the suitability of the developed immunosensor for directly analyzing SEA in milk samples. Results indicated that the mixed SAM-based SPR immunosensor has the potential for the specific detection of SEA.

Development of an immunosensor based on surface plasmon resonance for enumeration of Escherichia coli in water samples

Abstract An immunosensor for the rapid, sensitive and selective detection of generic Escherichia coli in water samples was developed on the basis of surface plasmon resonance (SPR). Antibodies against E. coli were immobilized on a sensor surface and water samples with different concentrations of E. coli were injected to the flow cell. The changes in the response unit (RU) due to the binding of different concentrations of bacteria were computed and a linear correlation (R2 = 0.976) was obtained between log E. coli concentration and the change in the RU with a working range of 9 × 101 and 1.8 × 105 cfu ml−1. The complete regeneration of the sensor surface was realized by using 1% SDS solution. The selectivity of the developed sensor was examined with Enterobacter aerogenes and Enterobacter dissolvens which did not produce any significant response. The ability of the developed sensor to detect E. coli in real water samples was investigated and the results were closed to that obtained from plate counting method. Based on these results, the developed immunosensor can be employed for rapid, label-free, sensitive and selective detection of E. coli in water samples.

SPR studies of carbohydrate–lectin interactions as useful tool for screening on lectin sources

Lectins are proteins or glycoproteins from plants, animals or microorganisms, which typically bind specifically to sugar residues, e.g., located in cell walls or membranes. This reaction might change the physiology of the cell wall and influences the metabolism inside the cell. Some lectins of plants stimulate the immune system by unspecific activation of T-cells or influence cell division; others cause agglutination of cells (e.g., erythrocytes) and are therefore from therapeutic interest.In a new approach, biomolecular interaction analysis (BIA) was utilised for a screening program on lectins. The BIA has been done by surface plasmon resonance (SPR). The system can be used either for characterisation of lectin-binding domains or for a screening on lectins from natural sources. Several lectin-binding surfaces on the basis of SPR have been established.

표면플라즈몬공명과 효소면역분석법을 이용한 살충제 카보후란 잔류물 검출

The pesticide is raising public interest in the world, because it causes damage to an environmental pollution and the human health remaining agricultural products and an ecosystem, in spite of the advantages. Particularly, each country restricts the residual pesticide and induces observance about the safety and usage standard so that they can control the amount of pesticide used and defend the safety of agricultural products. The habitual practice for the analysis of the residual pesticide depends on GC (gas chromatography), HPLC (high performance liquid chromatography) and GC/MS (gas chromatography/mass spectroscopy), which triturate the fixed quantity of samples, abstract and purify as a suitable organic solvent. These methods have the highly efficient in aspects of sensitivity and accuracy. On the other hand, they need the high cost, time consuming, much effort, expensive equipment and the skillful management. Carbofuran is highly toxic by inhalation and ingestion and moderately toxic by dermal absorption. As with other carbamate compounds, it is metabolized in the liver and eventually excreted in the urine. The half-life of carbofuran on crops is about 4 days when applied to roots, and longer than 4 days if applied to the leaves. This research was conducted to develop immunoassay for detecting carbofuran residue quickly on the basis of surface plasmon resonance and to evaluate the measurement sensitivity. Gold chip used was CM5 spreaded dextran on the surface. An applied antibody to Immunoassay was GST (glutathione-s-transferase). The association and the dissociation time were 176 second and 215 second between GST and carbofuran. The total analysis time using surface plasmon resonance was 13 minutes including regeneration time, on the other hand HPLC and GC/MS was 2 hours usually. The minimum detection limit of a permissible amount for carbofuran in the country is 0.1 ppm. The immunoassay method using surface plasmon resonance was 0.002 ppm.

Immunosensor for the detection of Vibrio cholerae O1 using surface plasmon resonance

An immunosensor for the detection of Vibrio cholerae O1 was developed on the basis of surface plasmon resonance (SPR). A protein G layer was fabricated by means of the chemical coupling between the free amine (-NH2) groups of protein G and the activated carboxyl groups present on a self-assembled monolayer (SAM) consisting of a mixture of 11-mercaptoundecanoic acid (MUA) and hexanethiol (molar ratio of 1:2). A monoclonal antibody, which was confirmed to be specific to V. cholera O1 by the Western blotting technique, was immobilized on the protein G layer. The formation of the SAM, the protein G layer and the sequential binding of the antibody against V. cholera O1 were investigated with SPR spectroscopy. As the number of fabricated layers increased, the minimum angle of plasmon resonance was increased accordingly. The target bacteria, V. cholera O1, was measured with the fabricated immunosensor, whose detection range was between 10(5) and 10(9) cells/mL.