Use Of Au Nanoparticles Research Articles

Photocatalytic Enhancement for CO2 Reduction Using Au Nanoparticles Supported on Fe‐Doped SrTiO3−δ Perovskite

This study focuses on the use of Au nanoparticles supported on the SrTiO3−δ perovskite doped with Fe ions as a photocatalyst for CO2 reduction and methanol production using water as the hydrogen supplier. The photocatalytic evaluation of the synthesized materials shows that Au nanoparticles supported on the SrTi(1−x)FexO3−δ perovskites can enhance photocatalytic CO2 reduction. The sample with the doping level x = 0.125 has the highest methanol production, 9.5 times more than the undoped sample and 3.5 times more than its counterpart without Au nanoparticles. The results of the DFT + U calculations show that the contributions from the iron atoms states reduce the energy gap in the perovskite composite, SrTi(1−x)FexO3−δ. Additionally, Fe incorporation endows the system with the capacity to create electron–hole pairs via direct band transitions at the high‐symmetry point R with the doping levels of x = 0.125 and x = 0.250.

Absorption enhancement of ultra-thin film Solar Cell using Fabry-Perot and plasmonic modes

In this paper, we investigate the photonic and plasmonic modes in order to enhance the absorption of ultrathin film Si Solar Cells. The simulations based on FEM show that these mechanisms enhance the absorption of the cell significantly. In order to investigate the plasmonic effects and use the amazing optical properties of localized surface plasmons (LSPs), multiple Au nanoparticles (NPs) with different radii have been used on the front surface of the Cell. Simulations show that the use of Au NPs with radii of 25, 50, and 75 nm simultaneously on the front surface of the Cell, increases the absorption dramatically. It is observed that multiple Au NPs with configuration illustrated in Case 5, enhance the absorption significantly due to the excitation of the multiple plasmonic modes in UV and Visible regions. In order to enhance the absorption in near-IR, we use Cu NPs on the backside of the cell. The highest average absorption of 84.7%, short-circuit current density of 36.7 (mA/cm2), and efficiency of 30.1% is achieved, with an increase of 177.7%, 178%, and 178.7% compared to Case 1, respectively. These methods promise the performance improvement of ultra-thin film solar cells and increase their application potential in Solar energy harvesting.

Probe –integrated electrochemical sensing platform for measuring trace levels of parathion pesticides residues in water using Au- nanoparticles anchored Nafion nano composite modified glassy carbon electrode

Nanomaterial represents a principal driver to the adoption of electrochemical sensors for pesticides residues in water. Thus, the current strategy reports facile and highly sensitive electrochemical probe for monitoring parathion residues in water. The probe was based upon the use of Au nanoparticles (AuNPs) functionalized Nafion nanocomposites modified glassy carbon electrode (Au NPs/Nafion/GCE). The surface morphology, effective surface area and electrocatalytic performance of the Au NPs/Nafion/GCE were recorded and assigned using a scanning electron microscopy (SEM), cyclic voltammetry (CV) and electronic spectra. A straightforward protocol based upon combination of Au NPs/Nafion/GCE and square wave- adsorptive cathodic stripping voltammetry at pH 7.0 was established for parathion detection. The probe displayed two linear responses between the catholic peak current (ip,c) at − 0.8 V versus parathion concentrations over the ranges from 1.07 × 10−6 - 1.07 × 10−5 and 1.99 × 10−9 - 9.0 × 10−7 M with limits of detection (LOD) and quantification (LOQ) of 6.06 × 10−10 M and 2.0 × 10−9 M, respectively. The probe exhibited excellent reproducibility, repeatability with RSD of ± 0.5% (n = 5) at 8.0 × 10−7 M parathion. The probe was applied for parathion detection in water and validated by HPLC. The experimental Student texp and Fexp values were less than the tabulated ttab (2.78) and Ftab (6.39) at 95% probability.

Effects of Au States in Thiol-Organosilica Nanoparticles on Enzyme-like Activity for X-ray Sensitizer Application: Focus on Reactive Oxygen Species Generation in Radiotherapy.

In radiotherapy, the use of Au nanoparticles (Au NPs) has been proposed to enhance cell damage by X-ray irradiation. Although the role of Au in radiotherapy is not fully understood, the catalytic activity of Au has been actively studied in the industrial field. Moreover, owing to their enzyme-like activity and high biocompatibility in vitro and in vivo, Au NPs present significant potential for biological applications. In this study, we incorporated different Au states both on the surface and embedded in thiol-organosilica (thiol-OS/Au series) to investigate the efficiency of anticancer cell activity of Au in radiotherapy. The thiol-OS/Au series comprised different Au(I)/Au(0) ratios and Au NPs, and different sizes of Au NPs were embedded in thiol-OS/Au. These thiol-OS/Au series samples were evaluated for enzyme-like activities in reactive oxygen species (ROS) generation by X-ray irradiation. Thiol-OS/Au embedded with small Au NPs (AC600/thiol-OS/Au) exhibited peroxidase (POD)-like activity under acidic conditions. This POD-like activity improved ROS generation and cytotoxicity under X-ray irradiation. Furthermore, AC600/thiol-OS/Au exhibited catalase (CAT)-like activity under basic conditions and showed no cytotoxicity toward nonirradiated cells. These results revealed the efficiency of functionalizing with small Au NPs that possess pH-controlled POD- and CAT-like activity as a radiosensitizer. We compared the suitability of using Au with different states to obtain the thiol-OS/Au series samples for application as radiosensitizers. The findings of this study will aid the design of efficacious strategies for the Au nanostructure-based radiotherapy of cancer cells.

An Indium–Gallium–Zinc–Oxide Layer Decorated With Gold Nanoparticles for Ultrahigh Sensitive Formaldehyde Gas Detection

An interesting formaldehyde (HCHO) gas sensor is fabricated using a sputtered indium–gallium–zinc–oxide (IGZO) layer decorated with gold (Au) nanoparticles (NPs). Based on the use of Au NPs, the efficiently increased surface area to volume ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${S}_{A}$ </tex-math></inline-formula> /V) ratio and catalytic reactivity cause the effective enhancement of HCHO gas sensing performance. Experimentally, under 20 ppm HCHO gas, an ultrahigh sensing response of 6855 with a response (recovery) time of 30 s (13 s) is obtained for the fabricated Au NP/IGZO sensor at 225 °C. A lower detectable content of 200 ppb HCHO/air gas at 225 °C is achieved. Furthermore, an improved GM(1, 1) model is used to enhance the prediction ability and meliorate data transmission efficiency within the acceptable reduction error range. This algorithm uses preprocessing to find the starting point of a sensing response and evaluate the influence of noise. This algorithm can efficiently improve the transmission efficiency without increasing the computational complexity. The studied device also displays the advantages of a simple structure, cost-effective production, and suitable application in the internet of things (IoT).

Improving Performance of ZnO Nanorods Photodetectors with the Use of Au Nanoparticles

Improving Performance of ZnO Nanorods Photodetectors with the Use of Au Nanoparticles

Study of a Formaldehyde Gas Sensor Based on a Sputtered Vanadium Pentoxide Thin Film Decorated with Gold Nanoparticles

Formaldehyde (HCHO) gas sensing properties of a new sensor based on a sputtered vanadium pentoxide (V2O5) thin film decorated with evaporated gold (Au) nanoparticles (NPs) are studied and reported herein. The use of Au NPs effectively increases the surface area/volume (SA/V) ratio and enhances the catalytic activity of Au metal. Experimentally, good p-type sensing characteristics, including a high sensing response ratio of 73.1% under 20 ppm HCHO/air gas and a small recovery time of 6.8 s at 225 °C, are obtained. An extremely low detecting level of 15 ppb HCHO/air is also acquired. Due to these advantages and the benefits of simple structure and easy fabrication, the studied Au NP/V2O5 device is an excellent candidate for p-type consumption formaldehyde gas sensing and complementary metal oxide sensor array (CMOSA) applications.

Water Decomposition Occurring During Laser Breakdown of Aqueous Solutions Containing Individual Gold, Zirconium, Molybdenum, Iron or Nickel Nanoparticles

Generation rates of hydrogen peroxide (H2O2), hydroxyl radicals (•OH), molecular hydrogen (H2), and molecular oxygen (O2) forming during the optical breakdown of aqueous colloidal solutions containing Au, Mo, Zr, Fe, and Ni nanoparticles have been studied. It is shown that the processes occurring during the dissociation of water molecules under the influence of laser breakdown plasma and leading to the formation of various chemical products depend on the material of the nanoparticles present in the colloid. It was found that the highest rates of generation of water decomposition products are observed in aqueous colloidal solutions of Fe and Ni nanoparticles. The use of Au nanoparticles leads to the lowest generation rate. In general, the materials from which the nanoparticles are made, depending on the efficiency of the formation of water decomposition products, are arranged as follows: Ni&amp;gt; Fe&amp;gt; Mo&amp;gt; Zr&amp;gt; Au.

Laser-Based Synthesis of Au Nanoparticles for Optical Sensing of Glyphosate: A Preliminary Study.

Nowadays, Au nanoparticles (AuNPs) capture great interest due to their chemical stability, optical properties, and biocompatibility. The success of technologies based on the use of AuNPs implies the development of simple synthesis methods allowing, also, the fine control over their properties (shape, sizes, structure). Here, we present the AuNPs fabrication by nanosecond pulsed laser ablation in citrate-solution, that has the advantage of being a simple, economic and eco-sustainable method to fabricate colloidal solutions of NPs. We characterized the stability and the absorbance of the solutions by Ultraviolet-Visible (UV-Vis) spectroscopy and the morphology of the AuNPs by Transmission Electron Microscopy. In addition, we used the AuNPs solutions as colorimetric sensor to detect the amount of glyphosate in liquid. Indeed, glyphosate is one of the most widely used herbicides which intensive use represents a risk to human health. The glyphosate presence in the colloidal AuNPs solutions determines the aggregation of the AuNPs causing the change in the color of the solution. The variation of the optical properties of the colloidal solutions versus the concentration of glyphosate is studied.

Advances in Designing Au Nanoparticles for Catalytic Epoxidation of Propylene with H2 and O2

Au nanoparticles, which can be used in various industrial and environmental applications, have drawn substantial research interest. In this review, a comprehensive background and some insights are provided regarding recent studies concerning the use of Au nanoparticles for catalytic propylene epoxidation with H2 and O2. Over the last two decades, substantial progress has been made toward the efficient production of propylene oxide (PO); this includes the design of highly dispersed Au catalysts on Ti-modified mesoporous silica supports, the optimization of catalytic epoxidation, and the determination of the mechanisms and reaction pathways of epoxidation. Particularly, the critical roles of catalyst synthesis, the types of material support, Au nanoparticle sizes, and the dispersion amounts of Au nanoparticles are emphasized in this review. In future studies, novel, practical, robust, and highly PO-selective Au nanoparticle catalyst systems are expected to be continually designed for the enhanced catalytic epoxidation of propylene.

Laser ablation in liquids for the assembly of Se@Au chain-oligomers with long-term stability for photothermal inhibition of tumor cells

For the potential use of Au nanoparticles (NPs) in photothermal therapy, it is important and effective to achieve the uniaxial assembly of Au NPs to allow enhanced absorption in the near infrared (NIR) region. Herein, we first presented the construction of amorphous selenium encapsulated gold (Se@Au) chain-oligomers by successive laser ablation of Au and Se targets in sodium chloride solution without other toxic precursors, stabilizers, or templating molecules. Se@Au chain-oligomers showed evidently enhanced NIR absorption and excellent photothermal transduction efficiency (η), which was higher than 47% at 808 nm. After being stored for 1 year, the Se@Au colloids still exhibited outstanding photothermal performance. The cytotoxicity assay demonstrated that there is negligible toxicity of Se@Au chain-oligomers in cells, but cell viability declined to only 1% in phototherapeutic experiments that were implemented in vitro. In intracellular Reactive Oxygen Species (ROS) generation measurements, Se@Au chain-oligomers could trigger a 35.9% increment of ROS upon laser irradiation. The possible synergetic effects between the anticancer function of Se and photothermal behaviors of Se@Au oligomers were intended to increase ROS level in cells. Therefore, such designed Se@Au chain-oligomers of high stability exhibit promising potential for their use as in vivo photothermal therapeutic agents.

Quantifying and optimizing photocurrent via optical modeling of gold nanostar-, nanorod-, and dimer-decorated MoS2 and MoTe2.

Finite element simulations through COMSOL Multiphysics were used to optically model systems composed of Mo dichalcogenide layers (MoTe2 and MoS2) and Au nanoparticles (spherical dimers, nanorods, and nanostars) to understand how their fundamental material properties as well as their interactions affect the photocurrent response. The absorption cross sections of the various Au nanoparticles linearly increase with respect to their increasing dimensions, hence being ideal tunable systems for the enhancement of the electric field in the dichalcogenide layers under visible and near infrared. The photocurrent through the MoTe2 and MoS2 substrates was enhanced by the addition of Au nanoparticles when the plasmonic response was localized in the area of the particle in contact with the substrate. Based on these findings, the use of Au nanoparticles can greatly improve the unique photocurrent properties of Mo dichalcogenides; however, nanoparticle orientation and size must be considered to tune the enhancement at the specific wavelengths. This computational work provides useful design rules for the use of plasmonic nanomaterials in photocatalytic and photocurrent enhancement of transition metal dichalcogenides.

Study of gold nanoparticles for mammography diagnostic and radiotherapy improvements.

A study on the possibility to use gold nanoparticles in mammography, both for a better image diagnostics and radiotherapy, is presented and discussed. We evaluate quantitatively the increment of dose released to the tumor enriched with Au-NPs with respect to the near healthy tissues, finding that for X-rays the increase can reach two orders of greater intensity. Gold nanoparticles continue to be investigated for their potential to improve existing therapies and to develop novel therapies. They are simple to obtain, can be functionalized with different chemical approaches, are stable, non-toxic, non-immunogenic and have high permeability and retention effects in the tumor cells. The possibility to use these for breast calcified tumors to be better treated by radiotherapy is presented as a possible method to destroy the tumor. The nanoparticles can be generated in water using the top-down method, should have a size of the order of 10-20nm and be treated to avoid their coalescence. Under diagnostic X-ray monitoring, the solution containing nanoparticles can be injected locally inside the tumor site avoiding injection in healthy tissues. The concentrations that can be used should be of the order of 10mg/ml or higher. An enhancement of the computerized tomography diagnostics using 80-150keV energy is expected, due to the higher mass X-ray coefficient attenuation with respect to other contrast media. Due to the increment of the effective atomic number of the biological tissue containing the gold nanoparticles, also an improvement of the radiotherapy effect using about 30keV X-ray energy is expected, due to the higher photoelectric cross sections involved. The study carried out represents a feasibility proposal for the use of Au-nanoparticles for mammographic molecular imaging aimed at radiotherapy of tumor nodules but no clinical results are presented.

Gold Nanoparticles by Laser Ablation for X-Ray Imaging and Protontherapy Improvements.

Gold nanoparticles, 5-20 nm in diameter, were generated with a pulsed Nd: YAG laser at 1010 W/cm2 at solution concentrations ranging between 1-100 mg/ml. The incremental X-ray contrast imaging using gold nanoparticles was investigated and measured. The study was performed with the aim to enhance the massive absorption coefficient of X-ray radiation in the tumor for medical image quality and to improve traditional X-ray radiotherapy or proton therapy. A simulation of proton therapy improvement was conducted using a human ocular melanoma model, placed 3 cm behind the eye lens, and testing 60 MeV protons. Calculations suggest that the local injection of a solution containing Au-NPs may increase the proton energy released in the tumor above 50%, with the dose in the surrounding tissues leading to an increased probability of tissue healing. A discussion on recent patents in the ambit of the preparation and use of Au nanoparticles in medical imaging and therapy is presented. Au nanoparticles were characterized using optical absorbance, X-ray fluorescence, SEM, and TEM microscopies. Biocompatible nanoparticle solutions were injected intravenously into tail veins of mice followed by X-ray imaging using 20-45 keV photons to evaluate the uptake and the clearance by different organs of the nanoparticles. Diagnostic X-ray images of mice in which the Au-NPs were injected showed high spatial resolution contrast of different organs having high up-take. A calculation of the dose released by X-rays, electrons and protons to the tumor site demonstrates that an increment of the order of 50% can be obtained using adapt solution concentration. The use of Au-NPs in biocompatible solutions injected in living organism permits their blood transport up to different organs. The NPs can be employed as contrast medium to enhance the medical image resolution and to prepare the cancer tissues to be exposed to ionization radiations in order to enhance the dose released to the tumor cells. This effect permits to reduce the total dose given to the patient and to increase the dose released to the tumor cells with respect to healthy ones.

A versatile solution-processed MoO3/Au nanoparticles/MoO3 hole contact for high performing PEDOT:PSS-free organic solar cells

Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) hole contact is widely used in organic solar cells (OSCs). In this work, we report the effort to develop a versatile solution-processed molybdenum trioxide (s-MoO3)/Au nanoparticles (NPs)/s-MoO3 (MAM) hole contact for application in PEDOT:PSS-free OSCs. The use of Au NPs is to improve the adhesion between the two s-MoO3 layers in the MAM hole contact. It shows that MAM hole contact enables to enhance the charge extraction through suppression of bimolecular recombination, and reduce the leakage current by improvement of contact property. Power conversion efficiency of 7.68% was obtained for MAM-based OSCs, with a blend system of poly[[4,8-bis[(2-ethylhexyl) oxy]benzo[1,2-b: 4,5-b’] dithiophene-2,6-diyl] [3-fluoro-2-[(2-ethylhexyl) carbonyl] thieno[3,4-b]-thiophenediyl]]: [6,6]- phenyl-C70-butyric-acid-methyl-ester, which is comparable to that of the PEDOT:PSS-based cells (7.48%). It demonstrates clearly that solution-processed MAM hole contact can be readily adopted to replace the widely used acidic PEDOT:PSS hole contact for application in PEDOT:PSS-free OSCs.

Optically stimulated luminescence radiation response of Au/Al2O3 phosphors

Crystal defects such as the doping of a variety of various elements are known to enhance the optically stimulated luminescent dosimeter (OSLD) performance of Al2O3. Moreover, the use of Au nanoparticles (NPs) has attracted considerable attention because of their photoluminescence properties. In this paper, a facile method is proposed to prepare and disperse Au NPs on an Al2O3 surface. The effects of Au nanoparticles on linearity between light emission and dose, reusability, and angular dependence of our proposed Au/Al2O3 OSLD are examined and discussed. We found that the linearity between light emission and dose with a wider dose range from 5Gy to 30Gy can be obtained. The sensitivities were tuneable by adjusting the Au/Al2O3 ratio. The result also shows a comparable angular dependence properties with commercially-available Al2O3:C dosimeters. In addition, the optical bleaching durations of Au/Al2O3 and Al2O3:C phosphors were also studied, in which the required bleaching time for our proposed Au/Al2O3 was 2h shorter than for Al2O3:C. In other words, this research also helps to reduce the bleaching time before re-use.

Efficient perovskite solar cells by combination use of Au nanoparticles and insulating metal oxide.

Achieving high open-circuit voltage and high short-circuit current density simultaneously is a big challenge in the development of highly efficient perovskite solar cells, due to the complex excitonic nature of hybrid organic-inorganic semiconductors. Herein, we developed a facile and effective method to fabricate efficient plasmonic PSC devices. The solar cells were prepared by incorporating Au nanoparticles (NPs) into mesoporous TiO2 films and depositing a MgO passivation film on the Au NP-modified mesoporous titania via wet spinning and pyrolysis of magnesium salt. The PSCs obtained by combining Au NPs and MgO demonstrated a high power conversion efficiency of 16.1%, with both a high open-circuit voltage of 1.09 V and a high short-circuit current density of 21.76 mA cm-2. The device achieved a 34.2% improvement in the power conversion efficiency compared with a device based on pure TiO2. Moreover, a significant improvement of the UV stability in the perovskite solar cell was achieved due to the combined use of Au NPs and insulating MgO. The fundamental optics and physics behind the regulation of energy flow in the perovskite solar cell and the concept of using Au NPs and MgO to improve the device performance were explored. The results indicate that the combined use of Au NPs and a MgO passivation film is an effective way to design high performance and high stability organic-inorganic perovskite photovoltaic materials.

Direct mercury determination in blood and urine by means of high-resolution continuum source graphite furnace atomic absorption spectrometry using gold nanoparticles as a chemical modifier

The use of Au nanoparticles as a chemical modifier permits the direct Hg determination in urine and blood samples by HR CS GFAAS.

Intact lipid imaging of mouse brain samples: MALDI, nanoparticle-laser desorption ionization, and 40keV argon cluster secondary ion mass spectrometry.

We have investigated the capability of nanoparticle-assisted laser desorption ionization mass spectrometry (NP-LDI MS), matrix-assisted laser desorption ionization (MALDI) MS, and gas cluster ion beam secondary ion mass spectrometry (GCIB SIMS) to provide maximum information available in lipid analysis and imaging of mouse brain tissue. The use of Au nanoparticles deposited as a matrix for NP-LDI MS is compared to MALDI and SIMS analysis of mouse brain tissue and allows selective detection and imaging of groups of lipid molecular ion species localizing in the white matter differently from those observed using conventional MALDI with improved imaging potential. We demonstrate that high-energy (40 keV) GCIB SIMS can act as a semi-soft ionization method to extend the useful mass range of SIMS imaging to analyze and image intact lipids in biological samples, closing the gap between conventional SIMS and MALDI techniques. The GCIB SIMS allowed the detection of more intact lipid compounds in the mouse brain compared to MALDI with regular organic matrices. The 40 keV GCIB SIMS also produced peaks observed in the NP-LDI analysis, and these peaks were strongly enhanced in intensity by exposure of the sample to trifluororacetic acid (TFA) vapor prior to analysis. These MS techniques for imaging of different types of lipids create a potential overlap and cross point that can enhance the information for imaging lipids in biological tissue sections.Graphical abstractSchematic of mass spectral imaging of a mouse brain tissue using GCIB-SIMS and MALDI techniquesElectronic supplementary materialThe online version of this article (doi:10.1007/s00216-016-9812-5) contains supplementary material, which is available to authorized users.

Construction and Immunological Evaluation of CpG-Au@HBc Virus-Like Nanoparticles as a Potential Vaccine.

Different types of vaccines have been developed to elicit active immunization to treat various diseases, while suffer from limitation of efficacy. Herein, a novel immunostimulatory nanocomposite (CpG-Au@HBc VLP) was rationally designed by self-assembling engineered virus-like particles encapsulating CpG-gold nanoparticle conjugates through electrostatic interactions. The monodispersed and uniformly sized CpG-Au@HBc VLP showed increased CD4+, CD8+ T cell numbers and stronger secretion of cytokine interferon-gamma than HBc VLPs adjuvanted with conventional Freund’s adjuvant. Furthermore, the use of Au nanoparticles also generated enhanced immunogenicity of CpG and VLPs on both humoral and cellular immune pathways, as followed from increased expressions of total HBc-specific antibody titer, CD4+ T cells, CD8+ T cells, cytokine interleukin-4, and interferon-gamma. These findings demonstrated that CpG-Au@HBc VLP nanocomposite could induce robust cellular and humoral immune response, which could be a potential vaccine for future prophylactic and therapeutic application.