Nanodisk Structure Research Articles

Tunable Plasmon Resonance in Silver Nanodisk-on-Mirror Structures and Scattering Enhancement by Annealing.

In this study, we evaluated the surface plasmon characteristics of periodic silver nanodisk structures fabricated on a dielectric thin-film spacer layer on a Ag mirror substrate (NanoDisk on Mirror: NDoM) through finite difference time domain (FDTD) simulations and experiments involving actual sample fabrication. Through FDTD simulations, it was confirmed that the NDoM structure exhibits two sharp peaks in the visible range, and by adjusting the thickness of the spacer layer and the size of the nanodisk structure, sharp peaks can be obtained across the entire visible range. Additionally, we fabricated the NDoM structure using electron beam lithography (EBL) and experimentally confirmed that the obtained peaks matched the simulation results. Furthermore, we discovered that applying annealing at an appropriate temperature to the fabricated structure enables the adjustment of the resonance peak wavelength and enhances the scattering intensity by approximately five times. This enhancement is believed to result from changes in the shape and size of the nanodisk structure, as well as a reduction in grain boundaries in the metal crystal due to annealing. These results have the potential to contribute to technological advancements in various application fields, such as optical sensing and emission enhancement.

Simulation study of multi-layer titanium nitride nanodisk broadband solar absorber and thermal emitter

Solar energy has always been a kind of energy with large reserves and wide application. It is well utilized through solar absorbers. In our study, the finite difference time domain method (FDTD) is used to simulate the absorber composed of refractory metal materials, and its absorption performance and thermal emission performance are obtained. The ultra-wide band of 200 nm–3000 nm reaches 95.93% absorption efficiency, of which the bandwidth absorption efficiency of 2533 nm (200 nm–2733 nm) is greater than 90%. The absorption efficiency in the whole spectrum range (200 nm–2733 nm) is 97.17% on average. The multilayer nanodisk structure of the absorber allows it to undergo strong surface plasmon resonance and near-field coupling when irradiated by incident light. The thermal emission performance of the absorber enables it to also be applied to the thermal emitter. The thermal emission efficiency of 95.37% can be achieved at a high temperature of up to 1500 K. Moreover, the changes of polarization and incident angle do not cause significant changes in absorption. Under the gradual change of polarization angle (0°–90°), the absorption spectrum maintains a high degree of consistency. As the incident angle increases from 0° to 60°, there is still 85% absorption efficiency. The high absorption efficiency and excellent thermal radiation intensity of ultra-wideband enable it to be deeply used in energy absorption and conversion applications.

Model and performance analysis of energy conversion in functionally graded flexoelectric semiconductor nanostructures

Energy systems converting efficiently from surrounding environment for powering semiconductor electronic components at nanoscale has attracted intense research interests. Due to the strong size dependency, flexoelectricity has been demonstrated as an excellent candidate implemented as nanoscale piezoelectric semiconductor energy harvesters. In this work, through a judicious exploitation of structural symmetry and nonuniformity, we theoretically study the energy conversion behaviors of a novel asymmetric nanodisk model composed of functionally graded (FG) flexoelectric semiconductor (FS) (FG-FS) materials while being loaded with thickness-extensional mechanical vibration. In numerical analysis, the material parameters have been treated with a general variation method under the Cartesian coordinate systems for simplicity. Taking into accounts of the nonuniform structural form and multi-field coupling features, we derived an octic governing equation with variable coefficients for the current analyzed FG-FS nanodisk structure, which is, however, almost impossible to obtain analytical solutions. To successfully address this issue and also further explore the improved performance and new phenomena induced by the FG type of non-uniform structural profile, we specially proposed an efficient tensor algorithm and reduced the octic governing equation into one quartic equation with variable coefficients and other four common quadratic equations. Later, we explicitly explored the effect of each physical parameter on the energy conversion performance of the FS energy harvester by studying the variations of the output electric power density and the energy conversion efficiency. Results illustrated that the electromechanical energy conversion behaviors of the studied FG-FS nanodisk can be properly tuned by not only the related material parameters but also their gradations. We believe our work have the potential to pave new way for the designs and manufacture of novel nano-electronic semiconductor components for the future practical applications.

Plasmonic gold disk nanoarrays-based surface lattice resonance sensor with high figure of merit and its near-field and far-field coupling characteristics

In the field of localized surface plasmon resonance sensing, narrow linewidth, high-quality factor, and high absorptivity have always been the goals that researchers are committed to achieving. The primary methods for achieving this goal are near-field coupling and far-field coupling. Due to the limitations of nanomanufacturing processes, current research often only focuses on single coupling methods such as far-field coupling or near-field coupling, with few relevant reports combining the two coupling methods. Based on this, this paper proposes a single-layer gold nano-disk array structure, which is simple and easy to manufacture. Through modal field analysis and structural parameter adjustment, some significant results have been achieved. On the one hand, the suggested gold nano-disk array structure yields a resonant peak based on far-field coupling with a full width at half maximum (FWHM) of less than 0.05 nm and a figure of merit of more than 15 000 (the quality factor is more than 20 000). On the other hand, it has been successfully accomplished to combine near-field coupling and far-field coupling, leading to a composite coupling peak that incorporates the benefits of both types of coupling. Moreover, this coupling peak has excellent characteristics such as narrow FWHM (less than 3 nm) and high absorptivity (up to 80.5%), which is superior to most reported sensing structures and more in line with practical sensing application requirements. In this paper, the potential of the gold disk array structure as a high-performance sensing structure is further explored, providing reference and new ideas for the design of easy-to-prepare and high-performance electromagnetic resonance devices.

Peptide-Based HDL as an Effective Delivery System for Lipophilic Drugs to Restrain Atherosclerosis Development.

PurposePeptide-based high-density lipoprotein (pHDL) structurally and functionally resembles the natural HDL as anti-atherosclerosis (AS) therapies. Since pHDL contains a large hydrophobic core, this study aims to evaluate the potentials of pHDL as a hydrophobic drug carrier and the efficiency of drug-loaded pHDL in the control of AS.MethodsThe pHDL encapsulation of hydrophobic components from natural plants, including curcumin (Cur) and tanshinone IIA (TanIIA), was achieved using one-step microfluidics. Then, morphological features and loading efficiencies of pHDL-Cur and pHDL-TanIIA were determined by TEM and high-performance liquid chromatography (HPLC), respectively. Taking the fluorescence advantage of Cur, localizations of loaded Cur in pHDL were investigated by fluorescence quenchers, and recruitments of Cur to AS plaques were assessed with ex vivo imaging. Based on anti-inflammatory properties of TanIIA, pHDL-TanIIA was accordingly developed to evaluate the anti-AS effects through examinations of plasma lipid parameters and pathological alterations of plaque-associated regions.ResultsBoth lipophilic Cur and TanIIA can be efficiently loaded into pHDL carriers. The resultant pHDL-Cur and pHDL-TanIIA inherit the homogeneous nano-disk structure of pHDL. By using pHDL-Cur, the encapsulated hydrophobics are tracked in the core of pHDL, and incorporations of Cur with pHDL vehicles greatly improve the bioavailability and association of Cur with AS plaques. Moreover, when loaded with TanIIA, which has established its role in anti-AS as an anti-inflammatory candidate, synergistic effects in reducing AS lesions and improving pathological alterations of main organs related to AS were achieved.ConclusionThe pHDL system could potentially be applied for both imaging and therapy in animal models of AS. Benefits of pHDL-based drug delivery will potentially extend the application scenarios of bioactive chemicals from natural plants which are underutilized due to features like low bioavailability and facilitate the clinical translation of synthetic HDL therapies in HDL-associated disorders, including but not limited to AS.

Miniaturized peptidomimetics and nano-vesiculation in endothelin types through probable nano-disk formation and structure property relationships of endothelins’ fragments

Abstract Endothelins (ETs), which are multi-functional-peptides with potential for antagonist-based-therapy in various physiological-malfunctionings, including cardiovascular, nephrological, oncologic, and diabetic conditions, may produce newer chemical entities and drug leads. The present study deals with molecular-modeling of the ETs’ sub-types, ET-I, II, and III to find the structure property-relationship (SPR) of the ETs, and individual fragments derived from the ET sub-type ET-I. The ETs peptidic tails’ amino acid (AA) sequence’s structural differences and similarities, various dissected fragments of the ET-I, and SPR comparison with the sarafotoxin-6b (SRT-6b), a structurally-related snake-venom, showed points of dissimilarities for their structural specifications, geometric disposition, and physico-chemical properties. The generation of miniaturized (shortened sequence) peptides towards offering peptidomimetic compounds of near- and far-values compared SPR with estimations for log P, hydration energy, and other molecular and quantitative structure activity relationship (QSAR) were based on random and ordered-fragments derived from the original ET-I AA’s sequence, and sequential distance changes in the original ET-I sequence’s chain of 1–21 AA. The feasibility of alternate and bond length parameters-based possible cysteine–cysteine cyclizations, sequence homology, AA’s positional demarcation, and presence/absence of cysteines, homology-based basic non-cysteine and cysteines-AA based cyclization, total structure and fragments end-to-end cyclizations, and geometrical analogy-based miniaturized sequence of the shorter AAs from the original ET-I sequence, together with mutated replacements with naturally constituent AAs of the ETs, and SRT-6 sequences were utilized. The major findings of the fragmented sequences, and sequences at par with the original ETs to provide structures similar to the size, volume and with molecular and electronic properties of electrostatic potential and total charge density distribution, crucial factors in receptor bindings were investigated. The SPRs, molecular properties, and QSAR values were estimated to compare and validate the findings with the known homologous compounds, ET-I, and its known and potent antagonists. The study resulted in leads of smaller and larger sizes of peptide-based compounds which may have prospects as potent antagonist and in future needs their bioactivity evaluations after the synthesis. Moreover, approach to plausible vesiculation of the ETs, and the involved processes and structural requirements, together with the molecular interactions in settling a nano-vesicle of the peptidic structure with a possible mechanism is also suggested.

Porous Co2VO4 Nanodisk as a High-Energy and Fast-Charging Anode for Lithium-Ion Batteries

HighlightsThe Li+ diffusion coefficient of Co2VO4 is evaluated by theoretical calculation to be as high as 3.15 × 10–10 cm2 s−1, theoretically proving Co2VO4 a promising anode in fast-charging lithium-ion batteries.A hexagonal porous Co2VO4 nanodisk (PCVO ND) structure is designed, featuring a high specific surface area of 74.57 m2 g−1 and numerous pores with a pore size of 14 nm.The PCVO ND shows excellent fast-charging performance (a high average capacity of 344.3 mAh g−1 at 10 C for 1000 cycles with only 0.024% capacity loss per cycle for 1000 cycles).

Voltage-controllable magnetic skyrmion dynamics for spiking neuron device applications

Voltage-controlled magnetic skyrmions have attracted special attention because they satisfy the requirements for well-controlled high-efficiency and energy saving for future skyrmion-based neuron device applications. In this work, we propose a compact leaky-integrate-fire (LIF) spiking neuron device by using the voltage-driven skyrmion dynamics in a multiferroic nanodisk structure. The skyrmion dynamics is controlled by well tailoring voltage-induced piezostrains, where the skyrmion radius can be effectively modulated by applying the piezostrain pulses. Like the biological neuron, the proposed skyrmionic neuron will accumulate a membrane potential as skyrmion radius is varied by inputting the continuous piezostrain spikes, and the skyrmion radius will return to the initial state in the absence of piezostrain. Therefore, this skyrmion radius-based membrane potential will reach a definite threshold value by the strain stimuli and then reset by removing the stimuli. Such the LIF neuronal functionality and the behaviors of the proposed skyrmionic neuron device are elucidated through the micromagnetic simulation studies. Our results may benefit the utilization of skyrmionic neuron for constructing the future energy-efficient and voltage-tunable spiking neural networks.

Dynamically Switchable Polarization-Independent Triple-Band Perfect Metamaterial Absorber Using a Phase-Change Material in the Mid-Infrared (MIR) Region.

A tunable metamaterial absorber (MMA) by reversible phase transitions in a mid-infrared regime is theoretically investigated. The absorber is composed of a molybdenum (Mo)-germanium-antimony-tellurium (Ge2Sb2Te5, GST)-Mo nanodisk structure superimposed on the GST-Al2O3 (aluminum oxide)-Mo film. Studies have shown that the combination of the inlaid metal-medium dielectric waveguide mode and the resonant cavity mode and the excitation of the propagating surface plasmon mode are the main reasons for the formation of the triple-band high absorption. Additionally, through the reversible phase change, the transition from high absorption to high reflection in the mid-infrared region is realized. The symmetry of the absorber eliminates the polarization dependence, and the near unity absorption efficiency can be maintained by incidence angles up to 60°. The presented method will enhance the functionality of the absorber and has the potential for the applications that require active control over light absorption.

All-Dielectric Metasurface Refractive Index Sensor with Microfluidics

Magnetic resonance and electrical resonance can be excited simultaneously by the incident light source in high refractive index all-dielectric metasurfaces. They can manipulate light waves to a certain extent and can be used in many fields. Silicon is widely used in all-dielectric metasurfaces due to its high refractive index and low loss in near infrared range. In this paper, we use silicon nanodisk structure as refractive index sensor and PDMS microfluidic channels as detection channels to realize liquid refractive index sensing. The magnetic resonance peak of the nanodisk structure is selected for sensing. The position of the magnetic resonance is shifted in the transmission spectrum with the change of the refractive index of the surrounding environment. When the refractive index increases, the resonance peak moves towards the long-wave direction, resulting in red shift, and vice versa. In this paper, the shift of resonance peak reaches 230 nm RIU−1.

Combined effects of surface plasmon coupling and Förster resonance energy transfer on the light color conversion behaviors of colloidal quantum dots on an InGaN/GaN quantum-well nanodisk structure

By forming nanodisk (ND) structures on a blue-emitting InGaN/GaN quantum-well (QW) template, the QWs become close to the red-emitting quantum dots (QDs) and Ag nanoparticles (NPs) attached onto the sidewalls of the NDs such that Förster resonance energy transfer (FRET) and surface plasmon (SP) coupling can occur to enhance the efficiency of blue-to-red color conversion. With a larger ND height, more QWs are exposed to open air on the sidewall for more QD/Ag NP attachment through QD self-assembly and Ag NP drop casting such that the FRET and SP coupling effects, and hence the color conversion efficiency can be enhanced. A stronger FRET process leads to a longer QD photoluminescence (PL) decay time and a shorter QW PL decay time. It is shown that SP coupling can enhance the FRET efficiency.

Nanophotonic Device Based on Fano Resonance in Engineered Slot Waveguide for Optical Detection of Viral Infections

A nanophotonic biosensing platform based on an engineered slot waveguide is proposed. The proposed device is based on Fano resonance which consists of a periodic arrangement of two rows of nano-disks and rectangular grating. The periodically arranged nano-disk structure in the form of engineered slot waveguide provides enhanced light-matter interaction and easy accommodation of bio-samples. The surface morphology of (3-Aminopropyl) trimethoxysilane (APTMS) as a functionalized layer on the silicon surface is experimentally analyzed. The proposed sensor device can detect very small refractive index change of 0.0008. Based on refractive index sensing, the device numerically exhibits a high sensitivity of 1463 nm/RIU for some viral infections including hepatitis B the with a Figure of Merit (FOM) of 471 for refractive index change of 0.02. The limit of detection for the proposed device is 1.02 $\times10^{-3}$ RIU (Refractive Index Unit). The proposed scheme with Fano like resonance spectrum carries a great potential for on-chip and off-chip nanoscale optical devices and sensors.

Optical properties of several ternary nanostructures* *Project supported by the National Natural Science Foundation of China (Grant Nos. 11774248 and 11974253).

To investigate the optical properties of the ternary nanostructures, the nanodisk, core–shell, and three-sphere structures are constructed. The extinction coefficients and electric near-field distributions of these structures are calculated by the discrete dipole approximation (DDA) method. The result shows that the nanodisk structure has the best extinction efficiency in the three structures. Furthermore, several three-material combinations of the nanodisk structures are investigated. The ternary nanodisk structure composed of TiO2 and two noble metals (Au, Ag or Pt) has higher extinction coefficient and near-field intensity than the nanodisk consisting of Au, TiO2 and a semiconductor (PbSe, Ge, MoS2, CdSe, CdS or TiO2). Especially, TiO2/Ag/Pt has the best extinction efficiency and the max electric near-field intensity. And the extinction spectra of TiO2/Ag/Pt and TiO2/Ag/Au structures are complementary in the visible range. This work conduces to the further research into ternary nanostructure and provides essential information about its performance in visible range.

Surface-enhanced Raman scattering based on hybrid surface plasmon excited by Au nanodisk and Au film coupling structure

A surface enhanced Raman scattering (SERS) substrate, Au nanodisk and Au film coupling structure with two surface plasmons resonant wavelengths is proposed. Finite-difference time-domain (FDTD) method was used to numerically optimize the parameters of the structure. The Raman characteristics of the substrate were experimentally studied, and the enhancement factor reached 2.9×104. The results show that the substrate is capable of performing SERS detection at two wavelengths, and has good SERS characteristics at both wavelengths. The SERS substrate has good uniformity, high physical stability, and no restrictions on the direction of linearly polarized light, which greatly improves the convenience and practicality of Raman detection.

Ultra-broadband and wide-angle perfect solar absorber based on TiN nanodisk and Ti thin film structure

At present, solar energy is widely used as a kind of clean energy. The main solar radiation range under AM 1.5 is about 300 ~ 3000 nm. In this paper, we designed an efficient, ultra-broadband perfect solar absorber to have as long absorption bands in this range as possible to help alleviate the energy problem. The simulation calculations and experiments of the solar absorber show that the absorption bandwidth with absorption greater than 90% is greater than 2100 nm. It is worth noting that the perfect absorption bandwidth with absorption greater than 99% has more than 1600 nm. The absorption rate over the whole wavelength range (300 nm–3000 nm) (weighted directly around the sun by solar AM 1.5) is more than 90%. We can effectively control the absorption spectrum by adjusting the structural parameters. In addition, the proposed solar absorber is polarization independent, both the transverse electrical (TE) mode and the transverse magnetic (TM) mode, Absorption remains above 80% when the wide incidence angle is as high as 50°. Our propose design has high broadband absorption and great potential for solar thermal energy harvesting, thermoelectrics, and thermal emitters applications.

Excitation of Nonradiating Anapoles in Dielectric Nanospheres.

Although the study of nonradiating anapoles has long been part of fundamental physics, the dynamic anapole at optical frequencies was only recently experimentally demonstrated in a specialized silicon nanodisk structure. We report excitation of the electrodynamic anapole state in isotropic silicon nanospheres using radially polarized beam illumination. The superposition of equal and out-of-phase amplitudes of the Cartesian electric and toroidal dipoles produces a pronounced dip in the scattering spectra with the scattering intensity almost reaching zero-a signature of anapole excitation. The total scattering intensity associated with the anapole excitation is found to be more than 10 times weaker for illumination with radially vs linearly polarized beams. Our approach provides a simple, straightforward alternative path to realizing nonradiating anapole states at the optical frequencies.

Synthesis, Formulation, and Characterization of Doxorubicin-Loaded Laponite/Oligomeric Hyaluronic Acid-Aminophenylboronic Acid Nanohybrids and Cytological Evaluation against MCF-7 Breast Cancer Cells.

As a synthetic clay material, laponite RDS (LR) was investigated as an effective drug carrier as a result of the special nanodisk structure together with the negative-charged surface to achieve enhanced cellular uptake and targeted delivery. In this research work, the synthesized oligomeric hyaluronic acid-aminophenylboronic acid (oHA-APBA) was entangled onto LR nanodisks to fabricate a valid targeted platform for breast cancer therapy. Briefly, through the formation of amide bonds, 3-APBA was connected to the chain of oHA with a substituted ratio of 4.0 ± 0.2% to synthesize oHA-APBA copolymer. Thereafter, doxorubicin (DOX) was inserted into the interlayer space of LR by the way of the ion exchange process, followed by an assembly with oHA-APBA as a targeted protection layer. The satisfactory drug encapsulation efficiency (> 80%) and narrow size distribution were achieved. The in vitro drug release study demonstrated the release of DOX from DOX@LR/oHA-APBA was sustained and acid dependent. In addition, after fitting the drug cumulative release of DOX@LR/oHA-APBA under different pH conditions with several kinetic models, it was identified that drug release from DOX@LR/oHA-APBA nanohybrids at pH5.0 was mainly dependent on both diffusion and ion exchange effects. However, under the condition of pH7.4, the drug was most efficiently released by diffusion effect. Importantly, DOX@LR/oHA-APBA showed remarkable cellular uptake and intracellular drug distribution in MCF-7 cells, which were consistent with inhibitory ability against MCF-7 cells. Hence, the high DOX loading capacity and enhanced cellular tracking can enlighten LR/oHA-APBA as an effective drug delivery carrier for breast cancer therapy.

Biofouling mitigation effect of thin film nanocomposite membranes immobilized with laponite mediated metal ions

Biofouling is an inevitable issue that can increase operating cost and reduce treatment efficiency, limiting the widespread application of thin film composite (TFC) membranes. Laponite (Lap) is a synthetic silicate nanoclay with the nanodisk structure, which can be used as a suitable metal ions carrier because it is ion exchangeable and biocompatible. In this work, Ag/Lap, Cu/Lap and Zn/Lap were synthesized by ion exchange method. Subsequently, Lap and metal ion exchanged Lap (M/Lap) were incorporated in polyamide (PA) layers to develop thin film nanocomposite (TFN) membranes by interfacial polymerization. The developed TFN membranes possessed improved water flux and remained a good NaCl rejection rate. Meanwhile, the incorporation of M/Lap endowed the TFN membrane with improved fouling resistance. The TFN-M/Lap membranes showed effective bactericidal properties against both E. coli and S. aureus, particularly the TFN-Ag/Lap membrane with prominent antibacterial properties against E. coli (99.2%) and S. aureus (95.1%). Fluorescence experiment, reactive oxygen species detection and the release of metal ions were also examined. The excellent antibiofouling properties of TFN-M/Lap membranes could be interpreted by cell damage resulting from contact between bacterial and metal ions. Our work provides the potential antibacterial materials and a facile approach to develop novel antibiofouling TFN membranes.

A skyrmion-based spin-torque nano-oscillator with enhanced edge

Abstract The oscillation frequency of the circular skyrmion motion in a nanodisk increases with the driving current density. However, the skyrmion may be destroyed at the nanodisk edge when the driving current density is larger than a threshold, which leads to a maximum oscillation frequency that may not be enough for ultrahigh frequency applications based on skyrmions. In this work, a modified nanodisk structure, in which a skyrmion can be driven by a large current density, is proposed. Numerical simulations demonstrate that when the edge of a ferromagnetic nanodisk has enhanced perpendicular magnetic anisotropy, the upper threshold of the skyrmion oscillation frequency can be increased by 75% compared to the original structure without enhanced edge. Our results may be useful for overcoming the frequency limit of the skyrmion-based spin-torque oscillator, which utilizes the current-induced oscillation of a skyrmion as the source of microwave power.

Localized Surface Plasmon Resonance Properties of Concentric Dual-Ring Nanodisk

The extinction spectral properties based on localized surface plasmon resonance (LSPR) of the concentric dual-ring nanodisk (CDRN) structure are investigated by discrete dipole approximation (DDA) and plasmon hybridization theory. The CDRN nanostructure shows flexible tunable multipole resonances in the near-infrared regime and the coupled resonance wavelengths depend on the structural parameters of the nanostructure, which has great potential in multichannel LSPR-based bio-sensing applications.