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[IEEE 2019 IEEE 4th Optoelectronics Global Conference (OGC) - Shenzhen, China (2019.9.3-2019.9.6)] 2019 IEEE 4th Optoelectronics Global Conference (OGC) - Harmonic Condensed Soliton Phase in a Mode-Locked Fiber Laser
摘要： A new harmonic mode-locked pattern is reported in passively mode-locked fiber laser (MLFL). The laser base on gold nanorods (GNRs) as a mechanism to trigger mode locking. By adjusting polarization controllers and pumping power, including fundamental mode-locked pulse, condensed soliton phase, soliton rain, harmonic condensed soliton phase have been observed. The harmonics condensed soliton phase were experimentally verified for the first time in the MLFL. The experimental results explained the conditions for the generation of condensed soliton phase and extend the pulse type of harmonic mode-locking (HML).
关键词： harmonic mode-locked,fiber laser,condensed soliton phase,gold nanorods
更新于2025-09-16 10:30:52
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Dumbbell–Like Silica Coated Gold Nanorods and their Plasmonic Properties
摘要： Silica coated gold nanorods with dumbbell-like morphology allowing dual functionalization in an individual nanostructure have attracted great attention for applications such as sensing and biological imaging. We report a detailed study on the feasibility of controlling the morphology of silica coating on gold nanorods. The morphology of the silica shell can be either cylindrical or dumbbell shaped. The morphology of the silica shell can be either cylindrical or dumbbell shaped. With constant GNR concentration, the ratio of CTAB and TEOS concentration is the key to determine the amount of available TEOS for silica deposition on GNR since the TEOS will diffuse towards the surface of GNRs. The effect of morphologies on surface-enhanced Raman scattering (SERS) performance was also investigated and we found that the dumbbell morphology of silica coated gold nanorods has the most significant SERS enhancement. Our study is significant in terms of the capability to control the dumbbell morphology of silica coated gold nanorods, which can eventually broaden the application of these plasmonic nanomaterials.
关键词： SERS,TEOS,plasmonic properties,dumbbell-like morphology,CTAB,Silica coated gold nanorods
更新于2025-09-12 10:27:22
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Plasmonic Metamaterial Gels with Spatially Patterned Orientational Order via 3D Printing
摘要： Optical properties can be programmed on mesoscopic scales by patterning host materials while ordering their nanoparticle inclusions. While liquid crystals are often used to define the ordering of nanoparticles dispersed within them, this approach is typically limited to liquid crystals confined in classic geometries. In this work, the orientational order that liquid crystalline colloidal hosts impose on anisotropic nanoparticle inclusions is combined with an additive manufacturing method that enables engineered, macroscopic three-dimensional (3D) patterns of co-aligned gold nanorods and cellulose nanocrystals. These gels exhibit polarization-dependent plasmonic properties that emerge from the unique interaction between the host medium’s anisotropic optical properties defined by orientationally ordered cellulose nanocrystals, from the liquid crystal’s gold nanorod inclusions, and from the complexity of spatial patterns accessed with 3D printing. The gels’ optical properties that are defined by the interplay of these effects are tuned by controlling the gels’ order, which is tuned by adjusting the gels’ cellulose nanocrystal concentrations. Lithe optical responsiveness of these composite gels to polarized radiation may enable unique technological applications like polarization-sensitive optical elements.
关键词： liquid crystals,optical properties,nanoparticles,plasmonic properties,cellulose nanocrystals,gold nanorods,3D printing
更新于2025-09-12 10:27:22
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Plasmon-Enhanced Fluorescence in Gold Nanorod-Quantum Dot Coupled Systems
摘要： Plasmon-exciton coupling is of great importance to many optical devices and applications. One of the coupling manifestations is plasmon-enhanced fluorescence. Although this effect is demonstrated in numerous experimental and theoretical works, there are different particle shapes for which this effect is not fully investigated. In this work electrostatic complexes of gold nanorods and CdSe/CdZnS quantum dots were studied. Double-resonant gold nanorods have an advantage of the simultaneous enhancement of the absorption and emission when the plasmon bands match the excitation and fluorescence wavelengths of an emitter. A relationship between the concentration of quantum dots in the complexes and the enhancement factor was established. It was demonstrated that the enhancement factor is inversely proportional to the concentration of quantum dots. The maximal fluorescence enhancement by 10.8 times was observed in the complex with the smallest relative concentration of 2.5 quantum dots per rod and approximately 5 nm distance between them. Moreover, the influence of quantum dot location on the gold nanorod surface plays an important role. Theoretical study and experimental data indicate that only the position near the nanorod ends provides the enhancement. At the same time, the localization of quantum dots on the sides of the nanorods leads to the fluorescence quenching.
关键词： quantum dot fluorescence,gold nanorod-quantum dot complexes,plasmon-enhanced fluorescence,plasmon-exciton coupling,gold nanorods
更新于2025-09-11 14:15:04
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Photothermally-Enhanced Molecular Delivery and Cellular Positioning on Patterned Plasmonic Interfaces
摘要： Photothermal conversion effect of plasmonic nanostructures is considered as a promising technique for cellular and molecular manipulations owing to controllability of local temperature. Therefore, this technique has been extensively applied to biological studies such as controlling cellular behavior, delivery of biologics, and biomolecular detection. Herein, we propose a novel method for directed cell positioning and photothermally-modulated molecular delivery to the cells using patterned plasmonic interfaces. Plasmonic substrates with gold nanorods (GNRs) and cell adhesion molecules fabricated by microcontact printing are optimized for cellular positioning on designated patterns. Through the photothermal conversion effect of GNRs on the pattern, we further demonstrate on-demand, light-induced delivery of drug molecules to the target cells. We expect that this approach will provide a new way to study single cellular behaviors and enhance molecular delivery to the target cells.
关键词： drug delivery,Photothermal conversion,gold nanorods,cell positioning,microcontact printing,plasmonic interfaces
更新于2025-09-11 14:15:04
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Magnetic Supramolecular Nanofibers of Gold Nanorods for Photothermal Therapy
摘要： Molecular aggregation triggered by physical and chemical stimuli and based on multiple noncovalent interactions has immense potential utility for modeling and mimicking biological systems and for the diagnosis and treatment of degenerative diseases. Herein the preparation, properties, and biological activities of a new type of organic–inorganic hybrid supramolecular nanofiber composed of gold nanorods, mitochondrion-targeting-peptide-coated iron oxide nanoparticles, and hyaluronic-acid (HA)-modified β-cyclodextrin is reported. These photothermal nanofibers, which grew along the direction of the geomagnetic field, induced severe mitochondrial damage in human adenocarcinoma cells (A549); and, more strikingly, the nanofibers greatly suppress metastasis and clear A549 cells in tumor-bearing mice upon irradiation with a near-infrared laser. The ability to recruit HA-receptor-expressing tumor cells and to target mitochondria, as well as the high photothermal conversion efficiency imparted by the gold nanorods, makes these supramolecular nanofibers a promising nanotherapy for cancer in general and metastasis-related malignancy in particular.
关键词： gold nanorods,supramolecular nanofibers,photothermal therapy,cyclodextrin,tumor metastasis
更新于2025-09-10 09:29:36
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Photoacoustic and fluorescent effects in multilayer plasmon-dye interfaces
摘要： Progress in understanding the cell biology and progression of disease depends on advanced imaging and labeling techniques. Here, we address this demand by exploring novel multilayered nanocomposites (MNCs) with plasmonic nanoparticles and adsorbing dyes in thin nonabsorbing shells as supercontrast multimodal photoacoustic (PA) and fluorescent agents in the near-infrared range. The proof of concept was performed with gold nanorods (GNRs) and indocyanine green (ICG) dispersed in a matrix of biodegradable polymers. We demonstrated synergetic PA effects in MNCs with the gold–ICG interface that could not be achieved with ICG and GNRs alone. We also observed ultrasharp PA and emission peaks that could be associated with nonlinear PA and spaser effects, respectively. Low-toxicity multimodal MNCs with unique plasmonic, thermal, and acoustic properties have the potential to make a breakthrough in PA flow cytometry and near-infrared spasers in vivo by using the synergetic interaction of plasmonic modes with a nearby absorbing medium.
关键词： gold nanorods,fluorescence,in vivo flow cytometry,biocompatible polymers,photoacoustic effect,indocyanine green,multilayer composite,fluorescence quenching
更新于2025-09-10 09:29:36
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Gram Scale Synthesis of Isolated Monodisperse Gold Nanorods
摘要： While the gold nanorods (AuNRs) possess a strong potential application in nanotechnology, plasmonics and sensing, the scale-up synthesis of isolated AuNRs in gram quantity remains a challenge. Nearly all previously reported methods produce aqueous solutions of CTAB-coated AuNRs in milligram quantities with the yield of ~20-30 % in terms of Au (I) to Au (0) conversion. In addition, it is difficult to remove CTAB bilayer from the surface of AuNRs and yet make them soluble and functionalized for further processing and chemical modification. This report describes the synthesis of monodisperse functionalized AuNRs (σ~5%) in gram quantities. Our approach is to increase the concentration of HAuCl4.3H20 in the growth solution to produce larger quantities of starting AuNRs and further reduce the remaining Au (I) ions onto the surface of AuNRs. The slow and controlled addition of reducing agent ascorbic acid (AA) continues to Au (0) (via disproportionation reaction) onto the surface of nanorods maintaining their uniform morphology without creating any unwanted impurities of various shapes. In addition, this approach significantly narrows the size distribution due to the continuous growth of partially grown AuNRs during the initial stage of the synthesis. To isolate one-gram quantity of AuNRs and make them functionalized for further chemical reactions, a ligand exchange approach was utilized where surfactant CTAB was replaced with 4-mercaptophenol. The thiol group from 4-mercaptophenol forms a covalent bond to the surface of AuNRs leaving free functional OH groups available for further chemical coupling reactions. For the ligand exchange process, a concentrated solution of 4-mercaptophenol in tetrahydrofuran (THF) solution was introduced into the AuNRs solution. Pure AuNRs, functionalized with 4-mercaptophenol were isolated by dispersion and rinsing with excess of THF, followed by centrifugation.
关键词： Amplification,Surface Functionalization,Gram Scale,Monodisperse,Gold Nanorods
更新于2025-09-10 09:29:36
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A Depolarized Dynamic Light Scattering Method to Calculate Translational and Rotational Diffusion Coefficients of Nanorods
摘要： A new analysis of depolarized dynamic light scattering data is presented, which allows the unambiguous determination of rotational and translational diffusions coefficients of nanorods in suspension. By visualizing data scaling, purely translational diffusive motions can be isolated from vertically polarized scattering, allowing the unique determination of rotational diffusion from the depolarized scattering. The method is applied to nanorods with four different aspect ratios, and compared with theoretical predictions. Diffusion coefficients obtained show good agreement with calculations based on the direct measurements of rod length and diameter. Where the theories are shown to be valid, the method allows the measurement of statistically meaningful particle sizes and aspect ratios.
关键词： depolarized dynamic light scattering,gold nanorods,Brownian motion,translational diffusion,rotational diffusion
更新于2025-09-10 09:29:36
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On-substrate porous-anodic-alumina-assisted gold nanostructure arrays: Meeting the challenges of various sizes and interfaces
摘要： Arrays of 0- and 1-dimentional noble-metal nanostructures aligned on solid substrates are in demand for nanocatalysis, bio- and optical sensing, or biomolecular analysis. Here we introduce a range of advances based on a systematic research towards the porous-anodic-alumina (PAA)-assisted on- substrate arrays of gold nanostructures, such as rods and spheres, spatially-separated and highly aligned on a metal or semiconductor supporting layer via a blend of the anodizing, re-anodizing, and post- anodizing treatments applied to a thin layer of Al superimposed on selected valve metals (W, Ti, Hf), metal bilayers (W/Ti), or binary metal alloy layers (W-Ti). The achievements are due to (1) the improved self-organization in the PAA thin films during the self-localizing high-current anodization of the upper Al layer at challenging potentials ranging 100 to 250 V and 20 to 5 V, and (2) the enhanced penetration of the alumina barrier layer by the undergrowing metal oxide due to the increasing polarization (re- anodizing). The protrusions of the undergrown metal oxide can be either selectively dissolved away providing perfect nanoholes in the alumina barrier layer or left as formed in the barrier layer and annealed in vacuum to increase their electron conductance and serve as the supports for subsequent metal electrodeposition. Additionally, the in-situ amplitude-modulated constant-current pulse deposition mode combined with the original surface-wiping technique to remove the overdeposited gold allow for smooth nucleation and uniform finishing of perfect arrays of on-substrate gold nanospheres and nanorods, having diameters from 10 to over 250 nm and length up to 2.5 ?m.
关键词： gold nanorods,electrodeposition,barrier layer dissolution,nanodots,porous anodic alumina
更新于2025-09-10 09:29:36