scholarly journals Synthesis and Characterization of Elongated-Shaped Silver Nanoparticles as a Biocompatible Anisotropic SERS Probe for Intracellular Imaging: Theoretical Modeling and Experimental Verification

Nanomaterials ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 256 ◽  
Author(s):  
Carlos Caro ◽  
Pedro Quaresma ◽  
Eulália Pereira ◽  
Jaime Franco ◽  
Manuel Pernia Leal ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Density Functional ◽  
Near Infrared ◽  
Rhodamine 6G ◽  
Theoretical Calculations ◽  
Near Field ◽  
Field Enhancement ◽  
Intracellular Imaging ◽  
Chemical Mechanisms ◽  
Cell Internalization

Progress in the field of biocompatible SERS nanoparticles has promising prospects for biomedical applications. In this work, we have developed a biocompatible Raman probe by combining anisotropic silver nanoparticles with the dye rhodamine 6G followed by subsequent coating with bovine serum albumin. This nanosystem presents strong SERS capabilities in the near infrared (NIR) with a very high (2.7 × 107) analytical enhancement factor. Theoretical calculations reveal the effects of the electromagnetic and chemical mechanisms in the observed SERS effect for this nanosystem. Finite element method (FEM) calculations showed a considerable near field enhancement in NIR. Using density functional quantum chemical calculations, the chemical enhancement mechanism of rhodamine 6G by interaction with the nanoparticles was probed, allowing us to calculate spectra that closely reproduce the experimental results. The nanosystem was tested in cell culture experiments, showing cell internalization and also proving to be completely biocompatible, as no cell death was observed. Using a NIR laser, SERS signals could be detected even from inside cells, proving the applicability of this nanosystem as a biocompatible SERS probe.

scholarly journals Towards rational design and optimization of near-field enhancement and spectral tunability of hybrid core-shell plasmonic nanoprobes

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Debadrita Paria ◽  
Chi Zhang ◽  
Ishan Barman
Keyword(s):  
Single Molecule ◽  
Rational Design ◽  
Near Infrared ◽  
Theoretical Calculations ◽  
Near Field ◽  
Field Enhancement ◽  
Infrared Region ◽  
Core Shell ◽  
Optimization Strategy ◽  
Design And Optimization

Abstract In biology, sensing is a major driver of discovery. A principal challenge is to create a palette of probes that offer near single-molecule sensitivity and simultaneously enable multiplexed sensing and imaging in the “tissue-transparent” near-infrared region. Surface-enhanced Raman scattering and metal-enhanced fluorescence have shown substantial promise in addressing this need. Here, we theorize a rational design and optimization strategy to generate nanostructured probes that combine distinct plasmonic materials sandwiching a dielectric layer in a multilayer core shell configuration. The lower energy resonance peak in this multi-resonant construct is found to be highly tunable from visible to the near-IR region. Such a configuration also allows substantially higher near-field enhancement, compared to a classical core-shell nanoparticle that possesses a single metallic shell, by exploiting the differential coupling between the two core-shell interfaces. Combining such structures in a dimer configuration, which remains largely unexplored at this time, offers significant opportunities not only for near-field enhancement but also for multiplexed sensing via the (otherwise unavailable) higher order resonance modes. Together, these theoretical calculations open the door for employing such hybrid multi-layered structures, which combine facile spectral tunability with ultrahigh sensitivity, for biomolecular sensing.

scholarly journals Metal–dielectric hybrid nanoantennas for efficient frequency conversion at the anapole mode

2018 ◽  
Vol 9 ◽  
pp. 2306-2314 ◽  
Author(s):  
Valerio F Gili ◽  
Lavinia Ghirardini ◽  
Davide Rocco ◽  
Giuseppe Marino ◽  
Ivan Favero ◽  
...  
Keyword(s):  
Frequency Conversion ◽  
Near Infrared ◽  
Strong Field ◽  
Second Harmonic ◽  
Near Field ◽  
Field Enhancement ◽  
High Refractive Index ◽  
Plasmonic Nanostructures ◽  
Ohmic Losses ◽  
Order Of Magnitude

Background: Dielectric nanoantennas have recently emerged as an alternative solution to plasmonics for nonlinear light manipulation at the nanoscale, thanks to the magnetic and electric resonances, the strong nonlinearities, and the low ohmic losses characterizing high refractive-index materials in the visible/near-infrared (NIR) region of the spectrum. In this frame, AlGaAs nanoantennas demonstrated to be extremely efficient sources of second harmonic radiation. In particular, the nonlinear polarization of an optical system pumped at the anapole mode can be potentially boosted, due to both the strong dip in the scattering spectrum and the near-field enhancement, which are characteristic of this mode. Plasmonic nanostructures, on the other hand, remain the most promising solution to achieve strong local field confinement, especially in the NIR, where metals such as gold display relatively low losses. Results: We present a nonlinear hybrid antenna based on an AlGaAs nanopillar surrounded by a gold ring, which merges in a single platform the strong field confinement typically produced by plasmonic antennas with the high nonlinearity and low loss characteristics of dielectric nanoantennas. This platform allows enhancing the coupling of light to the nanopillar at coincidence with the anapole mode, hence boosting both second- and third-harmonic generation conversion efficiencies. More than one order of magnitude enhancement factors are measured for both processes with respect to the isolated structure. Conclusion: The present results reveal the possibility to achieve tuneable metamixers and higher resolution in nonlinear sensing and spectroscopy, by means of improved both pump coupling and emission efficiency due to the excitation of the anapole mode enhanced by the plasmonic nanoantenna.

Laser Writing of Nanostructures on Magnetic Film Surfaces With Optical Near Field Effects

2001 ◽  
Vol 697 ◽  
Author(s):  
S. M. Huang ◽  
M. H. Hong ◽  
B. S. Luk'yanchuk ◽  
W. D. Song ◽  
Y. F. Lu ◽  
...  
Keyword(s):  
Theoretical Calculations ◽  
Near Field ◽  
Resonance Effect ◽  
Field Enhancement ◽  
Magnetic Film ◽  
Original Position ◽  
Single Shot ◽  
Optical Resonance ◽  
Field Effects ◽  
Laser Fluences

AbstractLaser directly writing of nanostrucrures on magnetic film surfaces with optical near field effects has been investigated. Spherical 0.99 m or 0.47 m silica particles were placed on Cr/CoCrPt multilayers. After laser illumination with an excimer laser for a single shot, pits were obtained at the original position of the particles using different laser fluences or particle size parameters. The mechanism of the formation of nanostructure pattern was discussed and found to be the near-field optical resonance effect induced by particles on the surface. A comparison with accurate theoretical calculations of near-field light intensity distribution showed good agreement with the experiment results. The method of particle enhanced laser irradiation allows the study of field enhancement effects as well as its potential applications for nanolithography.

scholarly journals Modifying Plasmonic-Field Enhancement and Resonance Characteristics of Spherical Nanoparticles on Metallic Film: Effects of Faceting Spherical Nanoparticle Morphology

Coatings ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 387 ◽  
Author(s):  
Vasanthan Devaraj ◽  
Hyuk Jeong ◽  
Chuntae Kim ◽  
Jong-Min Lee ◽  
Jin-Woo Oh
Keyword(s):  
Near Infrared ◽  
Near Field ◽  
Three Dimensional ◽  
Field Enhancement ◽  
Device Fabrication ◽  
Metallic Film ◽  
Linear Optics ◽  
Cross Sectional ◽  
Non Linear Optics ◽  
Surface Enhanced

A three-dimensional finite-difference time-domain study of the plasmonic structure of nanoparticles on metallic film (NPOM) is presented in this work. An introduction to nanoparticle (NP) faceting in the NPOM structure produced a variety of complex transverse cavity modes, which were labeled S11 to S13. We observed that the dominant S11 mode resonance could be tuned to the desired wavelength within a broadband range of ~800 nm, with a maximum resonance up to ~1.42 µm, as a function of NP facet width. Despite being tuned at the broad spectral range, the S11 mode demonstrated minimal decrease in its near field enhancement characteristics, which can be advantageous for surface-enhanced spectroscopy applications and device fabrication perspectives. The identification of mode order was interpreted using cross-sectional electric field profiles and three-dimensional surface charge mapping. We realized larger local field enhancement in the order of ~109, even for smaller NP diameters of 50 nm, as function of the NP faceting effect. The number of radial modes were dependent upon the combination of NP diameter and faceting length. We hope that, by exploring the sub-wavelength complex optical properties of the plasmonic structures of NPOM, a variety of exciting applications will be revealed in the fields of sensors, non-linear optics, device engineering/processing, broadband tunable plasmonic devices, near-infrared plasmonics, and surface-enhanced spectroscopy.

scholarly journals Plasmons driven by single electrons in graphene nanoislands

Nanophotonics ◽  
2013 ◽  
Vol 2 (2) ◽  
pp. 139-151 ◽  
Author(s):  
Alejandro Manjavacas ◽  
Sukosin Thongrattanasiri ◽  
F. Javier García de Abajo
Keyword(s):  
Cross Sections ◽  
Near Infrared ◽  
Near Field ◽  
Field Enhancement ◽  
High Sensitivity ◽  
Quantum Mechanical ◽  
Single Electrons ◽  
Electromagnetic Simulations ◽  
Highly Sensitive ◽  
Infrared Wavelengths

AbstractPlasmons produce large confinement and enhancement of light that enable applications as varied as cancer therapy and catalysis. Adding to these appealing properties, graphene has emerged as a robust, electrically tunable material exhibiting plasmons that strongly depend on the density of doping charges. Here we show that adding a single electron to a graphene nanoisland consisting of hundreds or thousands of atoms switches on infrared plasmons that were previously absent from the uncharged structure. Remarkably, the addition of each further electron produces a dramatic frequency shift. Plasmons in these islands are shown to be tunable down to near infrared wavelengths. These phenomena are highly sensitive to carbon edges. Specifically, armchair nanotriangles display sharp plasmons that are associated with intense near-field enhancement, as well as absorption cross-sections exceeding the geometrical area occupied by the graphene. In contrast, zigzag triangles do not support these plasmons. Our conclusions rely on realistic quantum-mechanical calculations, which are in ostensible disagreement with classical electromagnetic simulations, thus revealing the quantum nature of the plasmons. This study shows a high sensitivity of graphene nanoislands to elementary charges, therefore emphasizing their great potential for novel nano-optoelectronics applications.

scholarly journals The Quest for Low Loss High Refractive Index Dielectric Materials for UV Photonic Applications

2018 ◽  
Vol 8 (11) ◽  
pp. 2065 ◽  
Author(s):  
Yael Gutiérrez ◽  
Dolores Ortiz ◽  
José Saiz ◽  
Francisco González ◽  
Pablo Albella ◽  
...  
Keyword(s):  
Refractive Index ◽  
Near Infrared ◽  
Numerical Study ◽  
Near Field ◽  
Field Enhancement ◽  
Dielectric Materials ◽  
High Refractive Index ◽  
Heat Radiation ◽  
Aluminum Phosphide ◽  
Spectral Ranges

Nanostructured High Refractive Index (HRI) dielectric materials, when acting as nanoantennas or metasurfaces in the near-infrared (NIR) and visible (VIS) spectral ranges, can interact with light and show interesting scattering directionality properties. Also, HRI dielectric materials with low absorption in these spectral ranges show very low heat radiation when illuminated. Up to now, most of the studies of these kind of materials have been explored in the VIS-NIR. However, to the best of our knowledge, these properties have not been extended to the ultraviolet (UV), where their application in fields like photocatalysis, biosensing, surface-enhanced spectroscopies or light guiding and trapping can be of extraordinary relevance. Here, we present a detailed numerical study of the directional scattering properties, near-field enhancement and heat generation of several materials that can be good candidates for those applications in the UV. These materials include aluminum phosphide, aluminum arsenide, aluminum nitride, diamond, cerium dioxide and titanium dioxide. In this study, we compare their performance when forming either isolated nanoparticles or dimers to build either nanoantennas or unit cells for more complex metasurfaces.

scholarly journals Probing electron transport in plasmonic molecular junctions with two-photon luminescence spectroscopy

Nanophotonics ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Qiang Zhang ◽  
Danjun Liu ◽  
Qun Ren ◽  
Nicolae C. Panoiu ◽  
Li Lin ◽  
...  
Keyword(s):  
Electron Transport ◽  
Charge Transport ◽  
Theoretical Calculations ◽  
Near Field ◽  
Field Enhancement ◽  
Molecular Junctions ◽  
Luminescence Spectroscopy ◽  
Excitation Wavelength ◽  
Two Photon ◽  
The Impact

Abstract Plasmonic core–molecule–shell (CMS) nanojunctions provide a versatile platform for studying electron transport through conductive molecules under light excitation. In general, the impact of electron transport on the near-field response of CMS nanojunctions is more prominent than on the far-field property. In this work, we use two-photon luminescence (TPL) spectroscopy to probe the effect of electron transport on the plasmonic properties of gold CMS nanojunctions. Theoretical calculations show that the TPL response of such nanojunctions is closely related to the near-field enhancement inside the metal regions, and can be strongly affected by the electron transport through the embedded molecules. TPL excitation spectroscopy results for three CMS nanojunctions (0.7, 0.9 and 1.5 nm junction widths) reveal no perceivable contribution from their low-energy plasmon modes. This observation can be well explained by a quantum-corrected model, assuming significant conductance for the molecular layers and thus efficient charge transport through the junctions. Furthermore, we explore the charge transport mechanism by investigating the junction width dependent TPL intensity under a given excitation wavelength. Our study contributes to the field of molecular electronic plasmonics through opening up a new avenue for studying quantum charge transport in molecular junctions by non-linear optical spectroscopy.

EFFECT OF SILVER NANOPARTICLES ON THE FLUORESCENCE INTENSITY OF RHODAMINE 6G AND SULFORHODAMINE 101

2016 ◽  
Vol 75 (11) ◽  
pp. 1001-1008
Author(s):  
S.V. Nikolayev ◽  
V. V. Pozhar ◽  
M. I. Dzyubenko ◽  
K. S. Nikolayev
Keyword(s):  
Silver Nanoparticles ◽  
Fluorescence Intensity ◽  
Rhodamine 6G ◽  
Sulforhodamine 101

Theoretical and Experimental Evaluation of the Effect of Fluorinated Substituent on the Topological Landscape and Thermodynamic Stability of Zeolitic Imidazolate Framework Polymorphs

2018 ◽  
Author(s):  
Mihails Arhangelskis ◽  
Athanassis Katsenis ◽  
Novendra Novendra ◽  
Zamirbek Akimbekov ◽  
Dayaker Gandrath ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Mechanochemical Synthesis ◽  
Thermodynamic Stability ◽  
Experimental Evaluation ◽  
Density Functional ◽  
Theoretical Calculations ◽  
Zeolitic Imidazolate Framework ◽  
Functional Theory ◽  
Calorimetric Measurements ◽  
And Calorimetry

By combining mechanochemical synthesis and calorimetry with theoretical calculations, we demonstrate that dispersion-corrected periodic density functional theory (DFT) can accurately survey the topological landscape and predict relative energies of polymorphs for a previously inaccessible fluorine-substituted zeolitic imidazolate framework (ZIF). Experimental screening confirmed two out of three theoretically anticipated polymorphs, and the calorimetric measurements provided an excellent match to theoretically calculated energetic difference between them.<br>

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