Kinds Of Metal Nanoparticles Research Articles

(Digital Presentation) Metal Alloy Nanoparticles Dispersed in Amorphous Titanosilicate for Hydrogen Evolution Reaction Catalyst with Much Lower Overpotential Than That of Benchmark Catalyst in a Wide pH Range

Different kinds of metallic nanoparticles (Pd, Pt, Au, Cu, Ag etc.) are widely used in Electrochemical, Optoelectronic and Photovoltaic applications to harvest sunlight in order to increase the efficiency of devices.ETS-10, which is a synthetic microporous material consisting of –Ti-O-Ti-O-Ti- quantum wires running along [110] and [1-10] direction in polymorph B, has been of great interest in many applications like Electrochemical, Optoelectronic and Photovoltaic applications, due to its so unique (it contains periodically positioned quantum wires [-O-Ti(O-)4-O-] with a diameter (d) of ∼0.67 nm running along the two perpendicular directions in the crystal, tetrahedral framework structures and compostion, well defiend acidity, uniform pores, highly cation exchange selectivity, and good thermal stability are widely used as commercial catalysts, ion exchangers, and adsorbants) properties.As a results, Tafel slop clearly indicated that performance was much better than pure Pt plate and the quite stable upto 72 hours at all pH conditions. Figure 1

Chemodynamic/Photothermal Synergistic Cancer Immunotherapy Based on Yeast Microcapsule-Derived Au/Pt Nanoparticles

In recent years, microbiota-based tumor immunotherapy has become a hotspot in cancer research. However, the use of microorganisms alone to activate the immune response for antitumor therapy was unsatisfactory. In this study, we biosynthesized gold nanoparticles (AuNPs) and platinum nanoparticles (PtNPs) based on yeast microcapsules to activate the immune response for antitumor treatment in synergy with chemodynamic therapy (CDT) and photothermal therapy (PTT). We generated AuNPs and PtNPs on yeast microcapsules (YAP) and fabricated nanoscale particles (Bre-YAP) by ultrasonic fragmentation and differential centrifugation. Bre-YAP retained the glucan component of yeast as an adjuvant; in the meantime, these two kinds of metal nanoparticles contained were excellent CDT and PTT mediators. By inspection, they could reach a high level of distribution in tumors and tumor-draining lymph nodes (TDLNs). Under the laser irradiation of tumors, this immunological nanomaterial significantly remodeled the microenvironments of tumors and TDLNs. The primary tumors were effectively inhibited or even eradicated, and the overall survival of mice was significantly improved as well. Therefore, yeast microcapsule-based Bre-YAP with immune properties could be used as an effective cancer treatment modality.

A Semiclassical Model for Plasmon-Exciton Interaction From Weak to Strong Coupling Regime

Exploitation of strong light-matter interactions in plasmonic systems is vital for both fundamental studies and the development of new applications, which enables exceptional physical phenomena and promotes potential applications in nanophotonics, information communication, and quantum information processing. Here, we present an analytic model of the interaction between localized surface plasmon resonances and excitons, where a semiclassical method is utilized. Two kinds of metal nanoparticles (nanosphere and nanoellipsoid) are considered in our study. We derive the relations between the plasmon-exciton coupling strength and the geometry and material parameters of the coupled systems when the nanoparticles are put in an excitonic medium, which give an important guide to achieve strong plasmon-exciton coupling. Rabi splittings and anticrossing behavior are also demonstrated in the calculated extinction spectra. Furthermore, we propose an analytic model to describe the strong coupling between excitons and plasmon in a core-shell nanorod structure which is widely used in experiments. Our study provides a simple yet rigorous prescription to both analyze and design plexcitonic systems aiming at strong light-matter interactions.

Visual sensing of multiple proteins based on three kinds of metal nanoparticles as sensor receptors

We propose a colorimetric sensing array consisting of 4-aminothiophenol (p-ATP)-modified gold nanoparticles (Au NPs), silver nanoparticles (Ag NPs), and core-shell Au@Ag nanocubes (Au@Ag NCs) as sensing elements to identify multiple proteins according to the diverse colorimetric response patterns. In the absence of proteins, the sensor element solution itself did not agglomerate. After interacting with six proteins (lysozyme (LZM), hemoglobin (HGB), peroxidase from horseradish (HRP), bovine liver from peroxidase (CAT), trypsin from bovin pancreas (TRY), and pepsin (PEP)), due to the different binding ability between the sensing elements and various proteins, the sensing array exhibits a unique pattern of colorimetric variations, linear discrimination analysis (LDA) was applied to analyze the pattern and produced a clustering map for a clearer differentiation of these proteins.

Effect of metallic nanoparticles on amyloid fibrils and their influence to neural cell toxicity

The modification of amyloid fibrils cytotoxicity through exogenous nanomaterials is crucial to understand the processes controlling the role of protein aggregation in the related diseases. The influence of nanoparticles on amyloid stability yields great interest due to the small size and high surface area-to-volume ratio of nanoparticles. Various physico-chemical parameters play a role in the interaction of proteins and nanoparticles in solution, thus influencing the disaggregation of preformed fibrils. We have examined the influence of two kinds of metallic nanoparticles on lysozyme amyloid fibrils using a multi-technique approach and focalized their impact on cytotoxicity on human neuroblastoma cells (SH-SY5Y). In particular, fluorescence, infrared and circular dichroism spectroscopies, optical and atomic force microscopy experiments have been carried out; the results are analyzed to rationalize the effects of these complexes on neural cell viability. It is remarkable, that the fibrils in the presence of AuNPs, unlike fibrils alone or with AgNPs, do not generate a significant cytotoxic effect even at high concentration and an amyloid degradation effect is visible.

Plasmonic superlattices constructed by coupling electronic systems with metal nanoparticle arrays

We investigate the produced superlattice in electronic systems when coupled with metal nanoparticle arrays. The periodic potential is formed by the induced plasmonic excitations in the metal nanoparticles, with the period changing from several to hundreds of nanometers for either one- or two-dimensional cases. The theoretical method to calculate the periodic potential is presented analytically. Landau–Zener tunneling is studied in the one-dimensional case. The results show that the energy band structures of the superlattice could be designed or modified in a variety of ways, such as changing the structure parameters, combining different kinds of metal nanoparticles, and tuning the strength of the excitation field. These advantages make it a prospective platform to simulate condensed matter physics.

Assessing the uptake of 1-hexene on gasborne silver and gold nanoparticles

Chemisorption of hydrocarbons on metallic nanoparticles represents a fundamental step in catalytic processes of industrial relevance such as epoxidation reactions. In this work we study the adsorption of a simple unsaturated hydrocarbon (1-hexene) by gasborne silver and gold nanoparticles. Both kinds of metallic nanoparticles were produced by evaporation and condensation in a nitrogen flow, but using different methods. The uptake was determined by measuring the change of the mobility diameter of size selected 10 nm particles using a Tandem-Differential Mobility Analysis (T-DMA) setup. While no uptake of hexene by gold could be measured, the uptake on silver showed to be both concentration and temperature dependent. The uptake showed a maximum at a temperature of 170 ± 10 °C. The addition of oxygen was evaluated and its presence did not alter the results. FT-IR measurements confirmed the adsorbed state of 1-hexene on silver.

Stochastic approach to simulation of evaporation-triggered multiple self-assembly of mixed metal nanoparticles and their variable superradiance

We developed a design principle for the evaporation-triggered heterogeneous assembly of different kinds of metal nanoparticles in a two-dimensional environment. A dynamic Monte Carlo simulation shows the formation of island structures of gold nanoparticles (gold islands) surrounded by smaller silver nanoparticles (silver matrix) during the evaporation of organic solvent from the dispersion liquid on the water surface. Our developed principle revealed the spontaneous change in multiple interactions between gold and silver nanoparticles owing to the presence or the absence of solvation repulsion, which plays a crucial role in the formation of gold islands in the silver matrix. Not only the randomly arranged gold islands, but also the surrounding silver matrix phase contributed to the wavelength-tunable light scattering enhanced by a factor of 102 due to the superradiance effect. These results will pave the way for the design of multicolored optical devices based on random plasmonics via controlled interparticle interactions.

Facile fabrication of mesoporous silica micro-jets with multi-functionalities.

Self-propelled micro/nano-devices have been proved as powerful tools in various applications given their capability of both autonomous motion and on-demand task fulfilment. Tubular micro-jets stand out as an important member in the family of self-propelled micro/nano-devices and are widely explored with respect to their fabrication and functionalization. A few methods are currently available for the fabrication of tubular micro-jets, nevertheless there is still a demand to explore the fabrication of tubular micro-jets made of versatile materials and with the capability of multi-functionalization. Here, we present a facile strategy for the fabrication of mesoporous silica micro-jets (MSMJs) for tubular micromotors which can carry out multiple tasks depending on their functionalities. The synthesis of MSMJs does not require the use of any equipment, making it facile and cost-effective for future practical use. The MSMJs can be modified inside, outside or both with different kinds of metal nanoparticles, which provide these micromotors with a possibility of additional properties, such as the anti-bacterial effect by silver nanoparticles, or biochemical sensing based on surface enhanced Raman scattering (SERS) by gold nanoparticles. Because of the high porosity, high surface area and also the easy surface chemistry process, the MSMJs can be employed for the efficient removal of heavy metals in contaminated water, as well as for the controlled and active drug delivery, as two proof-of-concept examples of environmental and biomedical applications, respectively. Therefore, taking into account the new, simple and cheap method of fabrication, highly porous structure, and multiple functionalities, the mesoporous silica based micro-jets can serve as efficient tools for desired applications.

MHD squeezed flow of water functionalized metallic nanoparticles over a sensor surface

Present study is devoted to analyze the magnetohydrodynamics (MHD) squeezed flow of nanofluid over a sensor surface. Modeling of the problem is based on the geometry and the interaction of three different kinds of metallic nanoparticles namely: copper (Cu), alumina (Al2O3) and titanium dioxide (TiO2) with the homogeneous mixture of base fluid (water). The self-similar numerical solutions are presented for the reduced form of the system of coupled ordinary differential equations. The effects of nanoparticles volume friction, permeable velocity and squeezing parameter for the flow and heat transfer within the boundary layer are presented through graphs. Comparison among the solvent are constructed for both skin friction and Nusselt number. Flow behavior of the working nanofluid according to the present geometry has analyzed through Stream lines. Conclusion is drawn on the basis of entire investigation and it is found that in squeezing flow phenomena Cu–water gives the better heat transfer performance as compare with the rest of mixtures.

Synthesis of metal/poly(diphenylsilylenemethylene) nanocomposite thin films by pulsed laser ablation

A new technique to synthesize poly(diphenylsilylenemethylene) (PDPhSM) matrix nanocomposite thin films containing metal nanoparticles such as Ni, Al, Zn, and W produced by pulsed laser ablation has been developed. First, 1,1,3,3-tetraphenyl-1,3-disilacyclobutane (TPDC) films were deposited on 4 cm2 silicon substrates cut from c-Si wafers by conventional vacuum evaporation under a pressure of 4.0×10−3 Pa; then metal nanoparticles were deposited onto the TPDC films by pulsed laser ablation; finally the TPDC films with metal nanoparticles were heated in an electric furnace in an air atmosphere at 553 K for 10 min to induce ring-opening polymerization of TPDC. The results indicate that it is easy to synthesize metal/PDPhSM nanocomposite thin films by pulsed laser ablation. The morphologies and size of metal nanoparticles are closely related to the kinds of metal. Also, the polymerization efficiency depends on the kinds of metal nanoparticles deposited on the TPDC monomer films by pulsed laser ablation. In addition, The laser ablated metal nanoparticles penetrate into the TPDC monomer films during pulsed laser ablation while the DC sputtered metal nanoparticles just lay on the surface of TPDC films.

Numerical Analysis of Efficiency Enhancement in Plasmonic Thin-Film Solar Cells by Using the SILVACO TCAD Simulator

A physical model for simulating plasmonic solar cells (SCs) using the SILVACO TCAD simulator is established and the effects of some factors on the efficiency enhancement of the amorphous silicon thin film SCs are simulated. Through this simulation, it is demonstrated that our method can successfully simulate the optical and electrical properties of plasmonic solar cells without the overestimation of the characteristics and without the neglect of parameter change in the device operation process. It is shown that not only the size and kind of metal nanoparticles but also other factors, such as the surrounding medium, the distance from the bottom of particles to the device surface, and the light incident angle, play important roles in the optical and electrical properties of plasmonic SCs.

Gas–liquid interfacial plasmas: basic properties and applications to nanomaterial synthesis

A boundary between plasmas and liquids, which activates physical and chemical reactions, has successfully been generated under a low gas pressure condition by utilizing ionic liquids with unique properties such as fully ionized plasma state, extremely low vapor pressure and high heat capacity. Due to the formation and control of a sheath electric field just above the ionic liquid, the plasma-ion behavior can be manipulated and the effects of the ion irradiation on the ionic liquid are quantitatively revealed. In connection with the plasma-ion irradiation, the secondary electron emission is found to be enhanced by introducing the ionic liquid as a cathode electrode. The control of the plasma-ion irradiation flux and energy to the ionic liquid leads to the creation of various kinds of metal nanoparticles by the reduction in metal chlorides and the realization of efficient synthesis. Furthermore, the metal nanoparticles are synthesized with carbon nanotubes as a template in the ionic liquid using the plasma irradiation method. It is found that the high density, mono-dispersed and isolated metal nanoparticles are synthesized between or inside the carbon nanotubes by controlling the gas–liquid interfaced plasmas.

Metallic Nanoparticles Deposited on Carbon Microspheres: Novel Materials for Combinatorial Electrochemistry and Electroanalysis

This review deals with the preparation of metallic nanoparticles on glassy carbon microspheres and the use of these new hybrid materials for combinatorial electrochemistry and electroanalysis. First, the preparation of gold, silver and palladium nanoparticles on glassy carbon microspheres by a simple electroless procedure is described. Then, different types of electrodes modified with glassy carbon microspheres are described. These are: (i) glassy carbon electrodes modified by a composite film of glassy carbon microspheres and multi-walled carbon nanotubes, (ii) basal plane pyrolylic graphite electrodes modified by the abrasive attachment of glassy carbon microspheres and (iii) carbon-epoxy composite electrodes loaded with glassy carbon microspheres. The three types of electrode architectures described consist of metallic nanoparticles embedded in a carbon matrix and each of the electrode macrodisc surfaces actually correspond to a random metallic nanoelectrode array. Carbon-epoxy composite electrodes have good characteristics for their use as practical sensors. Furthermore, the use of several kinds of metallic nanoparticles allows the construction of a multi-analyte electrode and the screening of electroactive materials by following a combinatorial approach.

One-Step Synthesis of Gold and Silver Hydrosols Using Poly(N-vinyl-2-pyrrolidone) as a Reducing Agent

Synthesis of gold and silver hydrosols was carried out in a one-step process by reduction of aqueous solutions of metal salts using poly(N-vinyl-2-pyrrolidone) (PVP). Both kinds of metal nanoparticles were obtained without the addition of any other reducing agent, at low temperatures and using water as the synthesis solvent. Shape, size, and optical properties of the particles could be tuned by changing the employed PVP/metal salt ratio. It is proposed that PVP acts as the reducing agent suffering a partial degradation during the nanoparticles synthesis. Two possible mechanisms are proposed to explain the reduction step: direct hydrogen abstraction induced by the metal ion and/or reducing action of macroradicals formed during degradation of the polymer. Initial formation of the macroradicals might be associated with the metal-accelerated decomposition of low amounts of peroxides present in the commercial polymer.

Synthesis of metal–cadmium sulfide nanocomposites using jingle-bell-shaped core-shell photocatalyst particles

Photocatalytic deposition of gold (Au) and silver (Ag) nanoparticles was investigated using jingle-bell-shaped silica (SiO2)-coated cadmium sulfide (CdS) nanoparticles (SiO2/CdS), which each had a void space between the CdS core and SiO2 shell, as a photocatalyst. A size-selective photoetching technique was used to prepare the jingle bell nanostructure of SiO2/CdS. Nanoparticles of Au and Ag were deposited by irradiation of the photoetched SiO2/CdS in the presence of the corresponding metal complexes under deaerated conditions. Chemical etching of Au-deposited particles enabled the selective removal of CdS without any influence on the surface-plasmon absorption of Au. TEM analyses of the resulting particles suggested that some particles were encapsulated in hollow SiO2 particles, while other Au particles were deposited on the outer surface of the SiO2 shell. Emission spectra of the photoetched SiO2/CdS showed that the metal deposition developed a broad emission with a peak around 650 nm originating from surface defect sites, the degree being dependent on the kind of metal nanoparticles and their amount of deposition. This fact can be explained by the formation of metal–CdS binary nanoparticles having defect sites at the interface between metal and CdS.