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Reconfigurable Plasmonic Nanostructures Controlled by DNA Origami
摘要： Precise surface functionalization and reconfigurable capability of nanomaterials are essential to construct complex nanostructures with specific functions. Here we show the assembly of a reconfigurable plasmonic nanostructure, which executes both conformational and plasmonic changes in response to DNA strands. In this work, different sized gold nanoparticles(AuNPs) were arranged site-specifically on the surface of a DNA origami clamp nanostructure. The opening and closing of the DNA origami clamp could be precisely controlled by a series of strand displacement reactions. Therefore, the patterns of these AuNPs could be switched between two different configurations. The observed plasmon band shift indicates the change of the plasmonic interactions among the assembled AuNPs. Our study achieves the construction of reconfigurable nanomaterials with tunable plasmon ic interactions, and will enrich the toolbox of DNA-based functional nanomachinery.
关键词： DNA origami,Reconfigurable nanostructure,Gold nanoparticle,Plasmonic nanostructure
更新于2025-09-23 15:19:57
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Atoma??photon entanglement near a plasmonic nanostructure
摘要： We investigate the atom–photon entanglement between a four-level double V-type quantum system and a linearly polarized ?eld near a plasmonic nanostructure in the presence of a static magnetic ?eld. It is demonstrated that the magneto-optical effect can affect the atom–photon entanglement only when the atom is near the plasmonic nanostructure. We show that atom–photon entanglement increases when the quantum system is placed near the plasmonic nanostructure in order to modi?cation of the spontaneous decays of the quantum system. It is demonstrated that the degree of entanglement (DEM) increases by increasing the intensity of the linearly polarized ?eld when the quantum system is close to the surface of the plasmons. Moreover, we ?nd that near the plasmonic nanostructure, the static magnetic ?eld has a major role in increasing the steady-state DEM so that the DEM is completely demolished in the absence of the static magnetic ?eld. Finally, it is shown that the atom–photon entanglement near a plasmonic nanostructure is destroyed by free space decay rate.
关键词： degree of entanglement,static magnetic ?eld,atom–photon entanglement,plasmonic nanostructure,spontaneous emission
更新于2025-09-19 17:13:59
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Anisotropic Plasmonic Nanostructure Induced Polarization Photoresponse for MoS <sub/>2</sub> a??Based Photodetector
摘要： Techniques that give anisotropic properties to 2D materials with isotropic crystal structures will enable 2D material based photodetectors to possess polarization sensitivity in the detection of polarization, which will greatly improve the spatial resolution of photodetectors. Here, an MoS2-based polarization photodetector induced by anisotropic plasmonic nanostructure is prepared. The integrating anisotropic plasmonic structures on a few-layer MoS2 nanosheet can induce polarization photoresponse and enhance the responsivity of MoS2 device at the same time. The ratio of the maximum to minimum photocurrents reached 1.45 along two perpendicular polarizations. It proves that anisotropic nanostructure induced polarization sensitivity will pave a new way for the fabrication of polarization photodetectors.
关键词： polarization,plasmonic nanostructure,2D materials,photodetectors
更新于2025-09-19 17:13:59
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Preservation of entanglement and quantum correlations next to periodic plasmonic nanostructures
摘要： We study quantum correlations dynamics of two identical V-type quantum systems initially prepared in an extended Werner-like state, where each one independently interacts with a plasmonic nanostructure. Each V-type system can be decomposed as a two-level system with an additional third external level acting as an “umbrella level.” As the plasmonic nanostructure, we use a two-dimensional array of metal-coated dielectric nanoparticles. For the calculations, we combine quantum dynamics calculations using the density matrix equations and classical electromagnetic calculations. In order to describe the entanglement, we use the measure of entanglement of formation, while we use quantum discord to describe the total quantum correlations of our composite system. We ?nd that the presence of the plasmonic nanostructure leads to high suppression of spontaneous emission rates along with a high degree of quantum interference. These phenomena affect the evolution of both entanglement and quantum discord, while they signi?cantly prolong their dynamics.
关键词： Periodic plasmonic nanostructure,Quantum interference,Quantum discord,Entanglement of formation,Quantum correlations,V-type quantum system
更新于2025-09-19 17:13:59
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Hollow Porous Gold Nanoshells with Controlled Nanojunctions for Highly Tunable Plasmon Resonances and Intense Field Enhancements for Surface-Enhanced Raman Scattering
摘要： Plasmonic metal nanostructures with nanogaps have attracted great interest owing to their controllable optical properties and intense electromagnetic fields that can be useful for a variety of applications, but precise and reliable control of nanogaps in three-dimensional nanostructures remains a great challenge. Here, we report the control of nanojunctions of hollow porous gold nanoshell (HPAuNS) structures by a facile oxygen plasma-etching process and the influence of changes in nanocrevices of the interparticle junction on the optical and sensing characteristics of HPAuNSs. We demonstrate a high tunability of the localized surface plasmon resonance (LSPR) peaks and surface-enhanced Raman scattering (SERS) detection of rhodamine 6G (R6G) using HPAuNS structures with different nanojunctions by varying the degree of gold sintering. As the neck region of the nanojunction is further sintered, the main LSPR peak shifts from 785 to 1350 nm with broadening because the charge transfer plasmon mode becomes more dominant than the dipolar plasmon mode, resulting from the increase of conductance at the interparticle junctions. In addition, it is demonstrated that an increase in the sharpness of the nanojunction neck can enhance the SERS enhancement factor of the HPAuNS by up to 4.8-fold. This enhancement can be ascribed to the more intense local electromagnetic fields at the sharper nanocrevices of interparticle junctions. The delicate change of nanojunction structures in HPAuNSs can significantly affect their optical spectrum and electromagnetic field intensity, which are critical for their practical use in a SERS-based analytical sensor as well as multiple-wavelength compatible applications.
关键词： sintering,plasma etching,nanoporous gold,nanocrevice junction,surface-enhanced Raman scattering,plasmonic nanostructure
更新于2025-09-16 10:30:52
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Step-growth polymerization of traptavidin-DNA conjugates for plasmonic nanostructures
摘要： Here, we use two important biomaterials, protein and DNA, to construct self-assembled nanostructures through Watson-Crick base-paring of DNAs. We apply a simple magnetic separation method to purify traptavidin-DNA conjugates, and demonstrate synthesis of linear arrays of traptavidin-DNA conjugates via the step-growth polymerization approach with pre-determined DNA sequences. Using the traptavidin-DNA array as a template, we assemble gold nanoparticles to form linear plasmonic nanostructures in a programmable manner. The traptavidin-DNA conjugates thus provide a convenient platform for one-dimensional assembly of biotinylated nanomaterials for many biomedical applications from drug delivery to bio-sensing.
关键词： Traptavidin,Plasmonic nanostructure,Supramolecular assembly,Protein-DNA conjugate,DNA nanostructure
更新于2025-09-12 10:27:22
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Metal Oxide Grating based Plasmonic Refractive Index Sensor with Si layer in Optical Communication Band
摘要： Nanostructure based devices are crucial for many applications including surface plasmon resonance (SPR) sensors, in particular. In this work, an aluminum oxide (Al2O3) grating based plasmonic sensor with Si and Ag layers is proposed and simulated for the detection of hemoglobin (Hb) concentration (en route its refractive index measurement) in human blood in optical communication band (1400-1550 nm). The simulations are based on rigorous coupled wave analysis (RCWA). In general, a plasmonic sensor’s performance is closely evaluated in terms of sensitivity and figure of merit (FOM) but we have also extended the analysis by considering the SPR curves (of both reference and analyte samples) even more meticulously in terms of spectral FOM (FOM*) based on depth of reflectance curve. In order to further deepen the performance analysis, a quality factor (QF) is introduced by combining the maximum FOM* (m-FOM*) and FWHM of the analyte SPR curve. The effect of grating variables and the thicknesses of Si and Ag layers on FOM* and QF is analyzed. The simulation results are explained in relevant physical concepts such as radiation damping. The results indicate that the proposed sensor with optimized design parameters is able to provide significantly better sensitivity, detection limit, FOM, and m-FOM* compared with existing grating-based SPR sensors.
关键词： RCWA,Plasmonic nanostructure,grating,sensor,metal oxide,figure-of-merit
更新于2025-09-12 10:27:22
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Design and Analysis of a Ag Rhombus Nanoparticle Film-Coupled Plasmonic Nanostructure
摘要： We design a coupled plasmonic nanostructure, which consists of a Ag rhombus nanoparticle positioned over a silver ?lm, separated by a dielectric spacer layer, and perform numerical analysis by calculating the radiation loss resistance of this nanostructure as the perfect electric conductor metal based on the theory of transmission line modes. Compared with the nanocube or triangular nanodisk ?lm-coupled plasmonic nanostructures introduced in the previous works, a stronger electric ?eld enhancement was achieved in the Ag rhombus nanoparticle ?lm-coupled nanostructure because of the fact that the sharp tip of the rhombus nanoparticle can generate ?eld enhancement at a hot spot. In order to demonstrate that the sharp tip can con?ne the electromagnetic energies strongly, we also have calculated the Purcell factor and the far-?eld directivity of the quantum emitter in the vicinity of this nanostructure.
关键词： Purcell factor,electric ?eld enhancement,plasmonic nanostructure,Ag rhombus nanoparticle,far-?eld directivity
更新于2025-09-11 14:15:04
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Plasmon-enhanced upconversion photoluminescence: mechanism and application
摘要： The enhanced local electromagnetic field (EM) excited on the noble metallic nanostructure exhibits potential application in various areas, particularly in surface-enhanced spectroscopy (SES). Resonant coupling of SPs to luminous centers can strongly moderate the emission spectra properties, including the angular distribution, the intensity, the speed of radiative decay, and even the spectrum radiation polarization, or so-called plasmon-enhanced fluorescence (PEF). Due to the low efficiency of emission and small absorption section of rare earth ions, plasmon-enhanced upconversion photoluminescence(PUCPL) has attracted increasing attention recently. In this review, we focus on recent advanced reports on PUCPL. First, the mechanism of the conventional upconversion process and related reports will be introduced. We will then demonstrate that the introduction of plasmonic nanostructure, including nonperiodic and periodic metallic nanostructures, has a critical effect on upconversion nanoparticles(UCNPs). The recent advances in plasmon-enhanced fluorescence with metallic tip configuration are also noted. Finally, the recent applications of PUCPL are introduced. As a result, the combination of a rare-earth luminescent center with plasmonic nanostructure can largely expand the application of upconversion materials.
关键词： surface-enhanced spectroscopy,mechanism,plasmonic nanostructure,Plasmon-enhanced upconversion photoluminescence,application,rare earth ions
更新于2025-09-10 09:29:36