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Surface plasmon resonance

Xiaju Cheng, Rui Sun, Ling Yin, Zhifang Chai, Haibin Shi, Mingyuan Gao
Photocross-linkable Au nanoparticles are prepared through surface decoration of photolabile diazirine moieties. Both in vitro and in vivo studies indicate that the light-triggered cross-linking can dramatically shift the surface plasmon resonance of Au nanoparticles to near-infrared regions, which in consequence remarkably enhances their efficacy for photothermal therapy and photoacoustic imaging of tumors in vivo.
December 6, 2016: Advanced Materials
Tian Li, Xi Wu, Feng Liu, Na Li
This minireview summarizes analytical methods based on the light-scattering of plasmonic nanoparticles, primarily gold nanoparticles (AuNPs), at the single particle level from recent year publications. Examples are presented to illustrate simple and highly sensitive approaches based on AuNP localized surface plasmon resonance light-scattering with the dark-field microscopy imaging technology.
December 5, 2016: Analyst
D Daems, J Lu, F Delport, N Mariën, L Orbie, B Aernouts, I Adriaens, T Huybrechts, W Saeys, D Spasic, J Lammertyn
Analytical methods that are often used for the quantification of progesterone in bovine milk include immunoassays and chromatographic techniques. Depending on the selected method, the main disadvantages are the cost, time-to-result, labor intensity and usability as an automated at-line device. This paper reports for the first time on a robust and practical method to quantify small molecules, such as progesterone, in complex biological samples using an automated fiber optic surface plasmon resonance (FO-SPR) biosensor...
January 15, 2017: Analytica Chimica Acta
Qiu-Mei Feng, Zhen Zhou, Mei-Xing Li, Wei Zhao, Jing-Juan Xu, Hong-Yuan Chen
Proximal metallic nanoparticles (NPs) could quench the electrochemiluminescence (ECL) emission of semiconductor quantum dots (QDs) due to Förster energy transfer (FRET), but at a certain distance, the coupling of light-emission with surface plasmon resonance (SPR) result in enhanced ECL. Thus, the modification strategies and distances control between QDs and metallic NPs are critical for the ECL intensity of QDs. In this strategy, a SPR enhanced ECL sensor based on DNA tetrahedral scaffolds modified platform was reported for the detection of telomerase activity...
November 27, 2016: Biosensors & Bioelectronics
Asaf Ilovitsh, Pazit Polak, Zeev Zalevsky, Orit Shefi
We report a novel method for specific deactivation of conjugated enzymes using laser-heated gold nanoparticles. Current methods involve treatment of the entire solution, thereby inactivating all bioactive components. Our method enables inactivation of only a single or subset of targeted enzymes. The selected enzyme is pre-conjugated to gold nanoparticles, which are specifically heated by a laser tuned to their surface plasmon resonance. We demonstrate inactivation of a selected enzyme, glucose oxidase, within a mixture of biomolecules...
December 2, 2016: Cytometry. Part A: the Journal of the International Society for Analytical Cytology
Ivan Indutnyi, Yuriy Ushenin, Dirk Hegemann, Marianne Vandenbossche, Victor Myn'ko, Mariia Lukaniuk, Petro Shepeliavyi, Andrii Korchovyi, Roman Khrystosenko
The increase of the sensitivity of surface plasmon resonance (SPR) refractometers was studied experimentally by forming a periodic relief in the form of a grating with submicron period on the surface of the Au-coated chip. Periodic reliefs of different depths and spatial frequency were formed on the Au film surface using interference lithography and vacuum chalcogenide photoresists. Spatial frequencies of the grating were selected close to the conditions of Bragg reflection of plasmons for the working wavelength of the SPR refractometer and the used environment (solution of glycerol in water)...
December 2016: Nanoscale Research Letters
Vladimir Sofiyev, Hardeep Kaur, Beth A Snyder, Priscilla A Hogan, Roger G Ptak, Peter Hwang, Miriam Gochin
Low molecular weight peptidomimetic inhibitors with hydrophobic pocket binding properties and moderate fusion inhibitory activity against HIV-1 gp41-mediated cell fusion were elaborated by increasing the available surface area for interacting with the heptad repeat-1 (HR1) coiled coil on gp41. Two types of modifications were tested: 1) increasing the overall hydrophobicity of the molecules with an extension that could interact in the HR1 groove, and 2) forming symmetrical dimers with two peptidomimetic motifs that could potentially interact simultaneously in two hydrophobic pockets on the HR1 trimer...
November 19, 2016: Bioorganic & Medicinal Chemistry
Anthony J Clark, Tatyana Gindin, Baoshan Zhang, Lingle Wang, Robert Abel, Colleen S Murret, Fang Xu, Amy Bao, Nina J Lu, Tongqing Zhou, Peter D Kwong, Lawrence Shapiro, Barry Honig, Richard A Friesner
Direct calculation of relative binding affinities between antibodies and antigens is a long-sought goal. However, despite substantial efforts, no generally applicable computational method has been described. Here we describe a systematic free energy perturbation (FEP) protocol and calculate the binding affinities between the gp120 envelope glycoprotein of HIV-1 and three broadly neutralizing antibodies (bNAbs) of the VRC01 class. The protocol has been adapted from successful studies of small molecules to address the challenges associated with modeling protein-protein interactions...
November 28, 2016: Journal of Molecular Biology
Tao Guo, Yan Lin, Zhi Li, Shan Chen, Guoming Huang, Huirong Lin, Jun Wang, Gang Liu, Huang-Hao Yang
Gold nanorods (GNRs) are emerging as a promising nanoplatform for cancer theranostics because of their unique optical properties. However, they still suffer from many limitations, such as high cytotoxicity, low thermodynamic and biological stability, and a tedious process for integrating other imaging modalities, for further practical biomedical applications. In this work, a strategy by one-step coating of Gd2O2S around GNRs is reported to address these limitations of GNRs. After the coating of the Gd2O2S shell, the as-fabricated Gd2O2S coated GNRs (GNRs@Gd2O2S) show enhanced biocompatibility and photostability, and tunable localized surface plasmon resonance...
December 1, 2016: Nanoscale
Michele Scaravilli, Giuseppe Castaldi, Andrea Cusano, Vincenzo Galdi
In this paper, we investigate the possibility to excite Bloch surface waves (BSWs) on the tip of single-mode optical fibers. Within this framework, after exploring an idealized, proof-of-principle grating-coupling-based scheme for on-tip excitation of BSWs, we focus on an alternative configuration that is more robust with respect to fabrication-related non-idealities. Subsequently, with a view towards label-free chemical and biological sensing, we present a specific design aimed at enhancing the sensitivity (in terms of wavelength shift) of the arising resonance with respect to changes in the refractive properties of the surrounding environment...
November 28, 2016: Optics Express
Ren-Chao Jin, Jie Li, Ying-Hua Wang, Ming-Jie Zhu, Jia-Qi Li, Zheng-Gao Dong
Optical forces can be enhanced by surface plasmon resonances with various interesting characteristics. Here, we numerically calculated the optical forces enhanced by a new kind of toroidal dipolar resonance in a double-disk metastructure. The results show that this kind of optical force is competitive with ordinary plasmonic forces and typically can reach-182.5pNμm<sup>2</sup>mW<sup>-1</sup>. Influences of geometric parameters are discussed for the enhancement characteristic of optical force...
November 28, 2016: Optics Express
M N M N Perera, D Schmidt, W E K Gibbs, S Juodkazis, P R Stoddart
Mueller matrix ellipsometry has been used to determine the effective optical constants of island-like Ag films deposited by thermal evaporation. These films depart substantially from bulk silver with a prominent localized surface plasmon resonance. Moreover, despite the isotropic appearance, they exhibit uniaxial optical properties with the optical axis inclined by 83.4° from the substrate normal toward the direction of the incoming vapor flux. The uniaxial model supports the plasmon resonance peaks revealed by in-plane absorbance measurements of the films...
December 1, 2016: Optics Letters
I A Kolmychek, A N Shaimanov, A V Baryshev, T V Murzina
We present an experimental study of optical second harmonic generation (SHG) from arrays of nanostructures exhibiting collective plasmon resonances in the visible spectral range. Gold nanoparticles with the lateral diameter of 100 nm are packed in a square lattice with the period of 400 nm and are covered by a 90 nm thick iron garnet layer. We show an enhancement of SHG in the spectral vicinity of the lattice surface plasmon resonance. It is demonstrated that application of the external DC magnetic field results in a spectral shift of the SHG maximum up to 5 nm, accompanied by a pronounced phase modulation of the second harmonic wave...
December 1, 2016: Optics Letters
Di Bao, Khalid Z Rajab, Wei Xiang Jiang, Qiang Cheng, Zhen Liao, Tie Jun Cui
In recent years, the study of generating and detecting localized surface plasmons (LSPs) has been expanded from the optical regime to microwave regime. In this Letter, the compact spoof LSPs are introduced through both numerical simulations and near-field measurements. It is observed that the compact LSP structure could effectively reduce the resonant frequency with a stronger resonance strength (G<sub>dBsm</sub>) and a higher Q-factor. Both electric near-field and surface-current distributions are monitored to examine the resonance processes of the LSP particle...
December 1, 2016: Optics Letters
Sagnik Basuray, Avinash Pathak, Sangho Bok, Biyan Chen, Steven C Hamm, Cherian J Mathai, Suchismita Guha, Keshab Gangopadhyay, Shubhra Gangopadhyay
Classical methods for enhancing the electromagnetic field from substrates for spectroscopic applications, such as surface-enhanced Raman spectroscopy (SERS), have involved the generation of hotspots through directed self-assembly of nanoparticles or by patterning nanoscale features using expensive nanolithography techniques. A novel large-area, cost-effective soft lithographic technique involving glancing angle deposition (GLAD) of silver on polymer gratings is reported here. This method produces hierarchical nanostructures with high enhancement factors capable of analyzing single-molecule SERS...
December 1, 2016: Nanotechnology
Ying-Chen Chiang, Chun-Ta Huang, Wei Hsin Wang, Cheng-Chung Chang
This manuscript describes the preparation of water soluble aggregation-induced emission enhancement (AIEE)-based fluorescent organic nanoparticles (FONs). The fluorescence diversity of the FONs was investigated in the presence of silver nanowires. We observed that the emission of the FONs can be enhanced by mixing with the nanowires, which is believed to originate from resonance between the emission of the FONs and the surface plasmon resonances of the metal surface. That is, the AIEE phenomenon was promoted according to the metal-enhanced fluorescence (MEF) mechanism that can be used to build up a novel double emission enhancement (DEE) platform and to extend the range of AIEE applications...
December 1, 2016: Faraday Discussions
Quan Xu, Xueqian Zhang, Yuehong Xu, Quan Li, Yanfeng Li, Chunmei Ouyang, Zhen Tian, Jianqiang Gu, Wentao Zhang, Xixiang Zhang, Jiaguang Han, Weili Zhang
As an essential functionality, flexible focusing of surface plasmons (SPs) is of particular interest in nonlinear optics and highly integrated plasmonic circuitry. Here, we developed a versatile plasmonic metalens, a metasurface comprised of coupled subwavelength resonators, whose optical responses exhibit a remarkable feature of electromagnetically induced transparency (EIT). We demonstrate numerically and experimentally how a proper spatial design of the unit elements steers SPs to arbitrary foci based on the holographic principles...
November 29, 2016: Scientific Reports
Whitney Ingram, Steven Larson, Daniel Carlson, Yiping Zhao
By combining shadow nanosphere lithography with a glancing angle co-deposition technique, mixed-phase Ag-Cu triangular nanopatterns and films were fabricated. They were prepared at different compositions with respect to Ag from 100% to 0% by changing the relative deposition ratio of each metal. Characterizations by ellipsometry, energy dispersive x-ray spectroscopy, and x-ray diffraction revealed that the thin films and nanopatterns were composed of small, well-mixed Ag and Cu nano-grains with a diameter less than 20 nm, and their optical properties could be described by an effective medium theory...
January 6, 2017: Nanotechnology
So Young Lee, Ji Won Ha
Bimetallic core-shell gold nanorods are promising multifunctional orientation probes due to the synergetic effect of two different metals, as examined under an optical microscope. Herein, we performed a single particle study to characterize the optical properties of palladium-coated core-shell gold nanorods (Pd-AuNRs) using scattering-based dark-field (DF) and differential interference contrast (DIC) microscopy, and to examine their use as multifunctional orientation probes in biological and physical studies...
November 29, 2016: Physical Chemistry Chemical Physics: PCCP
Wendelin Wolfram, Kai M T Sauerwein, Christoph J Binder, Nicole Eibl-Musil, Hermann M Wolf, Michael B Fischer
HYPOTHESIS: Blood group antibodies are natural antibodies that develop early in life in response to cross-reactive environmental antigens in the absence of antigen encounter. Even later in life structural similarities in saccharide composition between environmental antigens such as bacterial polysaccharides and blood group A/B antigens could lead to changes in serum levels, IgM/IgG isotype, and affinity maturation of blood group anti-A/B antibodies. We addressed the question whether immunization with pneumococcal polysaccharide (PnP) vaccine Pneumo 23 Vaccine "Pasteur Merieux" (Pn23) could have such an effect in patients with type I diabetes mellitus (DM I), an autoimmune disease where an aberrant immune response to microbial antigens likely plays a role...
2016: Frontiers in Immunology
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