Gold Rods Research Articles

Combination of fluorescence spectroscopy and electrochemical technique as a novel and sensitive electro-optical detection system for gaseous and dissolved oxygen detection using nitrogen-doped quantum dots through the amperomric reduction of oxygen

A novel dissolved and gaseous oxygen electro-optical sensor was fabricated based on the dependency of the fluorescence intensity of a synthesized nitrogen-doped carbon nanodots (N-CDots) during the amperometric reduction of O2 at potential of −0.55V (vs. Ag/AgCl) for about 20s using a three-electrode system including gold rod as worker electrode, platinum rod as counter electrode and Ag/AgCl (3.0molL−1 Cl−) as reference electrode, followed by measuring the fluorescence intensity at excitation wavelength of 350nm. Under optimized condition, i.e. 5.0μgmL−1 of N-CDots, ionic strength of 0.5molL−1 and room temperature, the linear range for the dissolved oxygen was estimated to between 0.11 and 22μgmL−1 with detection limit of 0.07μgmL−1 (n=4). For gaseous oxygen the linear dynamic range was between 3.0 and 48.0% with the limit of detection of 0.95% (n=4). The response time (t90) of the sensor was estimated to be 20s. No interfering effect was observed during analysis of at least 200-fold excess (vs. 2.0μgmL−1 dissolved oxygen) of organic and inorganic species such as, K2SO4, KNO3, MgCl2, MnCl2, NaClO4, NaF, NH4Cl, CaCl2 and Na3PO4, except NO2− and HCO3− which interfered for respectively 12-fold and 75-fold excess. The reliability of the method was also evaluated via analyses of waste and industrial samples.

Unidirectional excitation of graphene plasmons in Au-graphene composite structures by a linearly polarized light beam.

Controllable manipulation of propagating surface plasmon polaritons is critical in plasmonics and important for nanophotonic applications. Here, we demonstrate theoretically that graphene plasmons (GPs) can be unidirectionally excited in an Au-graphene composite structure by a linearly polarized optical wave at the wavelength of 10.2 µm. The unidirectional ratio can reach as large as 900 with the incidence angle at 37.7° off normal, which is obtained by the angular spectrum of GPs. Moreover, the physical mechanism behind the unidirectional excitation is revealed to be the interference between anti-symmetric and symmetric amplitude distributions of GPs, which are induced by the gold rod antenna under the normal and grazing illuminations, respectively.

Multi-functional optical sensor based on plasmonic photonic liquid crystal fibers

A novel design of compact surface plasmon resonance multifunctional biosensor based on liquid crystal (LC) photonic crystal fiber (PCF) is proposed and studied. The suggested sensor has a central hole filled with LC as a temperature dependent material. Further, another large hole filled with liquid analyte has a gold nanorod as a plasmonic material. Therefore, the proposed senor can be used for temperature and analyte refractive index sensing via the coupling between the core guided modes in the LC core and the surface plasmon modes around the nano gold rod. The effects of the structure geometrical parameters are studied to maximize the sensitivity of the LC PCF biosensor. The numerical analysis is carried out using full-vectorial finite element method with perfectly matched layer boundary conditions. The reported multifunctional sensor offers high sensitivity of 5 nm/°C and 3700 nm/RIU (refractive index unit) for temperature and analyte refractive index sensing, respectively. To the best of the authors’ knowledge, it is the first time to introduce PCF biosensor with high sensitivity for temperature and analyte refractive index sensing as well.

A Paris System-Based Implant Approach to Hyperthermia Cancer Tumor with Gold Seeds and Ultrasound.

A Paris system-based implant approach has been used to improve the bio-heat distribution from implanted gold rods in insonated tissues. Experiments with single-plane implants using parallel equidistant 1.018±0.015cm height and 0.136±0.001cm diameter 24-K gold rods) arranged in triangular and square shapes were performed in Mus musculus white mice (medial dorsal region). The mice were anesthetized and gold rods were implanted by means of a trocar needle and the implanted region was insonated with a 4-cm diameter transducer oscillating with a nominal frequency of 1MHz and power of about 75W. Intramuscular tissue temperature measurements were recorded using implantable needle type thermocouples affixed to a portable Fluke thermometer. Superficial tissue temperature profile was also measured with a FLIR infrared camera and thermographic analysis was performed using the ImageJ computer software. In both cases, the central implant planes have been assigned to that approximately bisects all the implanted rods. Measured with the needle type thermistor, for the triangular implant, the percentage deviation between the maximum and minimum temperature within the triangular plane was 5%. For a square shape, this percentage deviation was 6%. The thermographic analysis have shown a deviation of 3 and 5% for the triangular and square shapes, respectively. The Paris system-based implant approach for gold rods implanted in tissue and exposed to ultrasound may greatly improve the bio-heat propagation and sustain a constant temperature profile inside triangular and square patterns formed by gold rods implants. Additionally, the Paris system may minimize ablations areas and treatment length in hyperthermia if used in cancer tumor treatment with gold seeds and ultrasound.

Determination of Soft Tissue Breakpoint Based on Its Temperature Enhancement Pattern: In Vivo and In Vitro Experiments.

The breakpoint of fresh commercial meats and in vivo mice has been assessed using tissue temperature enhancement pattern. A 1cm length and 0.1cm diameter gold rod was implanted in fresh chicken breast, beef, fish, and in vivo Mus musculus white mice and was insonated with ultrasound. The temperature enhancement of gold rods was measured with a needle type thermistor over a temperature range from 35 to 50°C. From these results the breakpoints were determined by plotting the gold rod temperature versus ultrasound exposure duration using the interception point of two curves fitted by a linear regression equations of thermal response above and below 43°C. The linear correlation coefficients for all fitted curves lie within 0.985 and 0.997. The breakpoints were found to be 42.1±1.1, 42.3±0.9, 42.6±0.8 and 43.5±0.6 for fish, chicken breast, beef and in vivo Mus musculus white mice, respectively. The interception of the thermal response curves above and below 43°C. Soft tissue temperature enhancement pattern has demonstrated to be a fast method to determine breakpoint. It denotes the temperature where cells may start to be destroyed and may be used to spot the startup point in dosimetry of hyperthermia cancer therapy.

Gold Rods Irradiated with Ultrasound for Combination of Hyperthermia and Cancer Chemotherapy.

The aim of this study was to analyze feasibility (in vitro and in vivo) the use of hyperthermia produced by gold rods irradiated with ultrasound and their combination with chemotherapy with doxorubicin. initially was determined the cell viability and Hsp70 levels after treatment by gold rods irradiated with ultrasound (GR+U) in cell culture. The pretreatment with GR+U combined with doxorubicin (DOX) was evaluated from IC50, caspase-3 expression and mechanisms of cell death by electron microscopy. For evaluate the in vivo effects was used solid Ehrlich carcinoma (SEC) Tumor. The animals received three treatments with the combination of GR+U+DOX over 16days. The cell viability was completely inhibited after 40min of treatment with GR+U and significant increases the expression of HSP70 was only observed after 10min of treatment. GR+U+DOX presented significant reduction of IC50 representing 50.7%, 76.5% 45.2% and 46.6% for cell lines K562, NCI-H292, Hep-2 and MCF-7 respectively. GR+U+DOX presented significant reduction of IC50 representing 50.7%, 76.5% 45.2% and 46.6% for cell lines K562, NCI-H292, Hep-2 and MCF-7 respectively. The caspase-3 level and ultraestructural analysis showed that treatment with GR+U+DOX enhances induction of apoptosis. Pretreatment with GR+U combined with doxorubicin (1mg) showed 87% inhibition against SEC. and no showed cardiotoxic effect. The combined treatment of GR+U and DOX exhibit synergistic characteristics observed by increasing the efficiency of doxorubicin.

Preclinical Validation of the Located Hyperthermia Using Gold Macro-Rods and Ultrasound as an Effective Treatment for Solid Tumors.

Hyperthermia, the procedure of raising the temperature of a part of or the whole body above normal for a defined period of time, is applied alone or as an adjunctive with various established cancer treatment modalities such as radiotherapy and chemotherapy. In this study used a method for inducing hyperthermia in solid tumors with a combination of gold macro rod (GR) and ultrasound, the feasibility of this technique was described only with computational models and in vitro. The Ehrlich tumor, derived from a mouse adenocarcinoma, has been used to investigate the bio-heat transfer and the effect of gold rods irradiated with ultrasound. The in vivo measurements demonstrated that the technique inhibited more 80% of the tumor growth in both experimental models tested. These results not only confirm the bio heat transfer to tissue as predicted by analytical calculation and in vitro measurements, but are also proved to be a potential alternative to kill cancer cells.

故縱之嫌：《西遊記》的召唤土地與鬼律叙述

故縱之嫌：《西遊記》的召唤土地與鬼律叙述

Hierarchically Templated Synthesis of Hollow Nanoporous Gold Rods and TiO2‐Coated Gold Rods

AbstractGold nanomaterials have shown promising applications in catalysis and sensing. Among the current directions in the research and development of gold catalysts, the exploration of new forms is one of the major priorities. Using bacteria as the supporting template and polystyrene spheres as the pore‐generation template, a hierarchical‐template synthesis strategy was developed in the present study to synthesize hollow nanoporous gold rods. The pore size can be easily adjusted by using polystyrene spheres (PSS) with different diameters as the template (the pore size is about 160 nm and 70 nm when using 200 nm and 110 nm PSS, respectively, as the template). Moreover, with the simple sol–gel method, different amounts of TiO2 can be coated on these nanoporous gold rods. The results showed the thermal stability and catalytic activity of the nanoporous gold rods were improved dramatically with moderate TiO2 coating. Using reduction of 4‐nitrophenol to 4‐aminophenol with sodium borohydride as the model reaction, excellent catalytic properties (reaction rate constant k=0.246 min−1) of the prepared TiO2‐coated gold rods catalysts were confirmed.

Polarization-Insensitive Magnetic Quadrupole-Shaped and Electric Quadrupole-Shaped Fano Resonances Based on a Plasmonic Composite Structure**Supported by the National Innovative Projects for College Students under Grant No 201310320025, the National Natural Science Foundation of China under Grant Nos 61401182 and 61372057, and the Priority Academic Program Development of Jiangsu Higher Education Institutions of China.

A combined structure with the unit cell consisting of four sub-units with 90° rotation in turn is designed. Each of sub-units is composed of two gold rods in transverse arrangement and one gold rod in longitudinal arrangement. Simulating electromagnetic responses of the structure, we verify that the structure exhibits the double Fano resonances, which originate from the coupling between magnetic quadrupoles and electric dipoles and the coupling between electric quadrupoles and electric dipoles. Simulation results also demonstrate that the structure is polarization-insensitive and shows an analogue of electromagnetically induced transparency at the two Fano resonances. Such a plasmonic structure has potential applications in photoelectric elements.

SU‐F‐E‐04: A Paris System‐Based Implant Approach to Hyperthermia Cancer Tumor with Gold Seeds and Ultrasound

Purpose:To apply the Paris system‐based implant for an uniform bio‐heat distribution from implanted gold rods in tissue insonated with ultrasound.Methods:Experiments with single‐plane implants using parallel equidistant 1.018 ± 0.015 cm height and 0.136 ± 0.001 cm diameter 24‐K gold rods) arranged in triangular and square shapes were performed in Mus Musculus white mice (medial dorsal region). The mice were anesthetized and gold rods were implanted by means of a trocar needle and the implanted region was insonated with a 4‐cm diameter transducer oscillating with a nominal frequency of 1 MHz and power of about 75 W. Intramuscular tissue temperature measurements were taken using implantable needle type thermocouples affixed to a portable Fluke thermometer. Superficial tissue temperature profile was also measured with a FLIR infrared camera and thermographic analysis were performed using the ImageJ computer software. In both cases, the central implant planes have been assigned to that approximately bisects all the implanted rods.Results:Measured with the needle type thermistor, for the triangular implant, the percentage deviation between the maximum and minimum temperature within the triangular plane was 5%. For a square shape, this percentage deviation was 6%. The thermographic analysis have shown a deviation of 3% and 5% for the triangular and square shapes, respectively.Conclusion:Based on the temperature measurements with needle type thermistor and thermographic analysis, the Paris system‐based implant approach for gold rods implanted in tissue and exposed to ultrasound may greatly improve the bio‐heat propagation and sustain a constant temperature profile inside triangular and square patterns formed by gold rods implants. Additionally, the Paris system may minimize ablations areas and treatment length in hyperthermia if used in cancer tumor treatment.

SU‐F‐E‐05: Determination of Breakeven Points of in Vitro Meats and in Vivo Mice Based On Tissue Temperature Enhancement Pattern

Purpose:To determine the breakeven points in fresh commercial meat and in vivo mice using the tissue temperature enhancement pattern.Methods:A 1 cm length and 0.1 cm diameter gold rod were implanted in fresh chicken breast, beef, fish, in vivo Mus Musculus white mice (medial dorsal region) and insonated with ultrasound. The temperature enhancement of gold rods was measured with a needle type thermistor over a temperature range from 35–50 oC. From these results the breakeven points were determined by plotting the gold rod temperature versus ultrasound exposure time and determining the interception point of two curves fitted by a linear regression of thermal response above and below 43 °C.Results:The linear correlation coefficients for all fitted curves lie within 0.97 and 0.99. The breakeven points were found to be the same for all kinds of fresh meat (fish = 42.1 ±1.1, chicken breast = 42.3 ±0.9, beef = 42.6 ±0.8) and in vivo Mus Musculus white mice (43.3 ±0.6). These temperatures agree with the standardized value (e.g. equivalent minutes at 43 °C) for comparison of thermal treatments (Proc. SPIE Int. Soc. Opt. Eng. 2003 June 2; 4954: 37).Conclusion:The interception of the thermal response curves above and below 43 °C may be used as a fast method and useful dosimetric tool in clinical research.

Functionalized Graphene Quantum Dots with Bi-Metallic Nanoparticles Composite: Sensor Application for Simultaneous Determination of Ascorbic Acid, Dopamine, Uric Acid and Tryptophan

The cost-effective technique has been performed on 2-aminoethanethiol (2-AET) functionalized GQDs with mono-metallic and bi-metallic nanoparticles such as rod gold nanoparticles (rAuNPs) and rod gold-platinum nanoparticles (rAu-PtNPs). In present study, the structures of nanomaterials were highligted by transmission electron microscope (TEM), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and X-ray diffraction (XRD) method. In addition, glassy carbon electrode (GCE) modified with rAu-PtNPs/GQDs nanomaterial (rAu-PtNPs/GQDs/GCE) was utilized in milk sample analysis.

Delocalization of Nonlinear Optical Responses in Plasmonic Nanoantennas.

Remote excitation and emission of two-photon luminescence and second-harmonic generation are observed in micrometer long gold rod optical antennas upon local illumination with a tightly focused near-infrared femtosecond laser beam. We show that these nonlinear radiations are emitted from the entire antenna and the measured far-field angular patterns bear the information regarding the nature and origins of the respective nonlinear processes. We demonstrate that the nonlinear responses are locally induced by a propagating surface plasmon at the excitation frequency, enabling thereby a polariton-mediated spatial tailoring and design of coherent and incoherent nonlinear responses.

Surface-enhanced terahertz spectroscopy using gold rod structures resonant with terahertz waves

Terahertz (THz) spectroscopy is a promising method to measure the spectrum of low-frequency modes of molecules or ensembles, such as crystals and polymers, including proteins. However, the main drawback of THz spectroscopy is its extremely low sensitivity. In the present study, we report on signal enhancement in THz spectroscopy achieved by depositing amino acid molecules or their derivatives on a gold rod structured silicon substrate whose localized surface plasmon resonance is exhibited in the THz frequency region. The distinct peaks derived from the enhancement of the inherent spectrum based on a molecular crystal were clearly observed when a longitudinal plasmon resonance mode of the gold rod structure was excited and the plasmon resonance band overlapped the molecular/intermolecular vibrational mode. We discuss the mechanism by which surface-enhanced THz spectroscopy was induced from the viewpoint of the enhancement of light-matter coupling due to plasmon excitation and the modulation of the plasmon band by dipole coupling between the plasmon dipole and molecular/intermolecular vibrational modes.

Synthesis of ligated-metal species by laser vaporization electrospray ionization (LAVESI)

We describe a new method for the production of hybrid metal species based on laser vaporization electrospray ionization (LAVESI) mass spectrometry. It consists of an ambient pressure laser vaporization of a metal rod located in the spray of an ESI source. Metal species generated by vaporization of the rod react with molecular ligands present in the spray to form ligated metal species, which are analyzed using a linear quadrupole ion trap. First results obtained by vaporizing silver, gold and copper rods and electrospraying a thioglycolic acid solution are reported. This leads to the formation of ligated metal species, which are transferred to the linear ion trap and mass analyzed. Their composition and size are discussed and compared to the ones obtained from electrospraying a metal salt solution.

Self-consistent nonlocal feedback theory for electrocatalytic swimmers with heterogeneous surface chemical kinetics.

We present a self-consistent nonlocal feedback theory for the phoretic propulsion mechanisms of electrocatalytic micromotors or nanomotors. These swimmers, such as bimetallic platinum and gold rods catalyzing decomposition of hydrogen peroxide in aqueous solution, have received considerable theoretical attention. In contrast, the heterogeneous electrochemical processes with nonlocal feedback that are the actual "engines" of such motors are relatively neglected. We present a flexible approach to these processes using bias potential as a control parameter field and a locally-open-circuit reference state, carried through in detail for a spherical motor. While the phenomenological flavor makes meaningful contact with experiment easier, required inputs can also conceivably come from, e.g., Frumkin-Butler-Volmer kinetics. Previously obtained results are recovered in the weak-heterogeneity limit and improved small-basis approximations tailored to structural heterogeneity are presented. Under the assumption of weak inhomogeneity, a scaling form is deduced for motor speed as a function of fuel concentration and swimmer size. We argue that this form should be robust and demonstrate a good fit to experimental data.

The effect of the shape and size of gold seeds irradiated with ultrasound on the bio-heat transfer in tissue.

The aim of this report is to propose a new methodology to treat prostate cancer with macro-rod-shaped gold seeds irradiated with ultrasound and develop a new computational method for temperature and thermal dose control of hyperthermia therapy induced by the proposed procedure. A computer code representation, based on the bio-heat diffusion equation, was developed to calculate the heat deposition and temperature elevation patterns in a gold rod and in the tissue surrounding it as a result of different therapy durations and ultrasound power simulations. The numerical results computed provide quantitative information on the interaction between high-energy ultrasound, gold seeds and biological tissues and can replicate the pattern observed in experimental studies. The effect of differences in shapes and sizes of gold rod targets irradiated with ultrasound is calculated and the heat enhancement and the bio-heat transfer in tissue are analyzed.

Depolarized Dynamic Light Scattering a method to analyse Particle Shape and Size

"Dynamic Light Scattering (DLS) is already a widely used method for small particle size distribution analysis [1]. The main purpose of this method is the determination of particle sizes, respectively the hydrodynamic radius in the sub-microscopic range, i.e. 1 nm up to few µm. It is based on the Brownian motion of those particles. Light scattering methods are non-invasive and therefore a great advantage in the field of particle analysis [2a]. The next generation of Dynamic Light Scattering devices will apply depolarized dynamic light scattering (DDLS) [2b]. This technique allows to obtain beside radius distributions also information about the particle shape. However, for some time technical drawbacks made it almost unfeasible to use it for biological samples. In cooperation with the University of Hamburg we developed the first experimental set-up of a DDLS system to be used in the laboratory to analyze and characterize protein solutions as well as suspensions of nano crystals, suitable for Free-Electron-Laser applications. The fundamental difference to so far known ""standard"" DLS is that the scattered light is separated into two signal pathways, a vertically and a horizontally polarized component, applying a special designed beam splitter. DDLS allows to measure the translational diffusion and the rotational constants simultaneously. Both constants are derived from the decay times of the autocorrelation functions. With the equations of Perrin the system is capable of calculating the axis ratio of the particles, approximating the real particle shape as a rotational ellipsoid. For calibration and tests gold rod particles of 575 nm in length and 25 nm diameter were applied. The first biological sample, which was analyzed by DDLS was hemocyanin from Limulus polyphemus hemolymph [3a], which occurrs predominantly as hexamers, dodecamers and traces of higher aggregates occur at high pH. In summary, together with additional advantages like viscosity independent measurements and ten times higher resolution compared to DLS, the DDLS-technique is optimal to characterize biological samples to be used for crystallization experiments and to score solutions and suspensions of nano-crystals to be used for Free-Electron Laser applications [3b]."

Probing the surface oxidation of chemically synthesised gold nanospheres and nanorods

In this study, the electrochemical behaviour of commercially available gold spheres and rods stabilised by carboxylic acid and cetyl trimethyl ammonium bromide (CTAB) moieties, respectively, are investigated. The cyclic voltammetric behaviour in acidic electrolyte is distinctly different with the nanorods exhibiting unusual oxidative behaviour due to an electrodissolution process. The nanospheres exhibited responses typical of a highly defective surface which significantly impacted on electrocatalytic activity. A repetitive potential cycling cleaning procedure was also investigated which did not improve the activity of the nanorods and resulted in deactivating the gold spheres due to decreasing the level of surface defects.