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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 343 records · Page 19
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

WE-G-303-01: Physical Bases for Gold Nanoparticle Applications in Radiation Oncology and X-Ray Imaging

Over the last decade, there has been a growing interest in applying nanotechnology to cancer detection, treatment, and treatment monitoring. Advances in nanotechnology have enabled the fabrication of nanoparticles from various materials with different shapes and sizes. Nanoparticles can be accumulated preferentially within tumors by either “passive targeting” through a phenomenon typically known as “enhanced permeability and retention” or “active targeting” in which nanoparticles are conjugated with antibodies or peptides directed against tumor and/or stromal markers. The tumor specificity of nanoparticles in conjunction with their unique physicochemical properties offers many novel strategies for cancer treatment and detection. For example, notable approaches in the radiation oncology setting include the use of gold nanoparticles for radiation response modulation of tumor or normal tissue and thermal ablation or hyperthermia treatment of tumors. Some of these approaches are currently being tested either on humans or on animals and, very likely, will become the clinical reality in the near future. Various computational and experimental techniques have also been applied to address unique research issues associated with nanoparticles and may become the standard tools for future investigations and clinical translations. Therefore, both clinicians and researchers may need to be properly educated about the basic principles as well as the promise of nanoparticle-based applications with regard to the future of cancer diagnostics and therapeutics. This symposium will familiarize the audience with the potential applications of nanoparticles in oncologic imaging and therapy using specific illustrative examples. The audience will be properly oriented by these illustrative examples to the multiple avenues for collaborative research amongst interdisciplinary teams of physicists, clinicians, engineers, chemists, and biologists in industry and academia. Learning Objectives: Understand the physical bases of gold nanoparticle applications for radiosensitization and x-ray fluorescence imaging Understand the parameters that define gold nanoparticle-mediated radiosensitization in biological systems Understand the potential of magnetic nanoparticle characterization of the microenvironment Understand the various strategies for radiolabeling of nanoparticles and their applications S.C. and S.K. acknowledge support from MD Anderson Cancer Center, NIH (R01CA155446 and P30CA16672) and DoD (W81XWH-12-1-0198); J.W. acknowledges support from NIH (U54CA151662-01); W.C. acknowledges support from the University of Wisconsin-Madison, NIH (R01CA169365, P30CA014520, and T32CA009206), DoD (W81XWH-11-1-0644 and W81XWH-11-1-0648), and ACS (125246-RSG-13-099-01-CCE)

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

WE-G-303-02: Gold Nanoparticles as Radiosensitizers - What Does It Take To Go From the Bench to the Bedside?

Over the last decade, there has been a growing interest in applying nanotechnology to cancer detection, treatment, and treatment monitoring. Advances in nanotechnology have enabled the fabrication of nanoparticles from various materials with different shapes and sizes. Nanoparticles can be accumulated preferentially within tumors by either “passive targeting” through a phenomenon typically known as “enhanced permeability and retention” or “active targeting” in which nanoparticles are conjugated with antibodies or peptides directed against tumor and/or stromal markers. The tumor specificity of nanoparticles in conjunction with their unique physicochemical properties offers many novel strategies for cancer treatment and detection. For example, notable approaches in the radiation oncology setting include the use of gold nanoparticles for radiation response modulation of tumor or normal tissue and thermal ablation or hyperthermia treatment of tumors. Some of these approaches are currently being tested either on humans or on animals and, very likely, will become the clinical reality in the near future. Various computational and experimental techniques have also been applied to address unique research issues associated with nanoparticles and may become the standard tools for future investigations and clinical translations. Therefore, both clinicians and researchers may need to be properly educated about the basic principles as well as the promise of nanoparticle-based applications with regard to the future of cancer diagnostics and therapeutics. This symposium will familiarize the audience with the potential applications of nanoparticles in oncologic imaging and therapy using specific illustrative examples. The audience will be properly oriented by these illustrative examples to the multiple avenues for collaborative research amongst interdisciplinary teams of physicists, clinicians, engineers, chemists, and biologists in industry and academia. Learning Objectives: Understand the physical bases of gold nanoparticle applications for radiosensitization and x-ray fluorescence imaging Understand the parameters that define gold nanoparticle-mediated radiosensitization in biological systems Understand the potential of magnetic nanoparticle characterization of the microenvironment Understand the various strategies for radiolabeling of nanoparticles and their applications S.C. and S.K. acknowledge support from MD Anderson Cancer Center, NIH (R01CA155446 and P30CA16672) and DoD (W81XWH-12-1-0198); J.W. acknowledges support from NIH (U54CA151662-01); W.C. acknowledges support from the University of Wisconsin-Madison, NIH (R01CA169365, P30CA014520, and T32CA009206), DoD (W81XWH-11-1-0644 and W81XWH-11-1-0648), and ACS (125246-RSG-13-099-01-CCE)

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

The Shift of the Peak of a Localized Plasmon Resonance in Granulated Gold Films on the Surface of a-C:H

Spectra of optical density of granulated 2-nm-thick gold films deposited on the surface of thin films of amorphous hydrogenated carbon (a-C:H) on quartz substrates are investigated. A shift of the peak corresponding to the localized surface plasmon resonance toward the shorter wavelengths by 32 nm upon an increase in the optical bandgap of the a-C:H films from 0.8 to 2.4 eV is demonstrated. Simultaneously, an increase in intensity and narrowing of the plasmon-resonance band in spectra of gold nanostructures is observed. This fact indicates that formation of the granulated gold films on the surface of a-C:H films depends on the specific structural properties of the latter.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2017

Photonics of 2D gold nanolayers on sapphire surface

Gold layers with thicknesses of up to several nanometers, including ordered and disordered 2D nanostructures of gold particles, have been formed on sapphire substrates; their morphology is described; and optical investigations are carried out. The possibility of increasing the accuracy of predicting the optical properties of gold layers and 2D nanostructures using quantum-mechanical models based on functional density theory calculation techniques is considered. The application potential of the obtained materials in photonics is estimated.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2017

Evaluating the potential of gold, silver, and silica nanoparticles to saturate mononuclear phagocytic system tissues under repeat dosing conditions

Background: As nanoparticles (NPs) become more prevalent in the pharmaceutical industry, questions have arisen from both industry and regulatory stakeholders about the long term effects of these materials. This study was designed to evaluate whether gold (10 nm), silver (50 nm), or silica (10 nm) nanoparticles administered intravenously to mice for up to 8 weeks at doses known to be sub-toxic (non-toxic at single acute or repeat dosing levels) and clinically relevant could produce significant bioaccumulation in liver and spleen macrophages. Results: Repeated dosing with gold, silver, and silica nanoparticles did not saturate bioaccumulation in liver or spleen macrophages. While no toxicity was observed with gold and silver nanoparticles throughout the 8 week experiment, some effects including histopathological and serum chemistry changes were observed with silica nanoparticles starting at week 3. No major changes in the splenocyte population were observed during the study for any of the nanoparticles tested. Conclusions: The clinical impact of these changes is unclear but suggests that the mononuclear phagocytic system is able to handle repeated doses of nanoparticles.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2023

Gold Nanoparticles AuNP Decorated on Fused Graphene-like Materials for Application in a Hydrogen Generation

The search for a sustainable, alternative fuel source to replace fossil fuels has led to an increased interest in hydrogen fuel. This combustible gas is not only clean-burning but can readily be produced via the hydrolysis of sodium borohydride. The main drawback of this reaction is that the reaction occurs relatively slowly and requires a catalyst to improve efficiency. This study explored a novel composite material made by combining gold nanoparticles and fused graphene-like materials (AuFGLM) as a catalyst for generating hydrogen via sodium borohydride. The novel fused graphene-like material (FGLM) was made with a sustainable dextrose solution and by using a pressure-processing method. Imaging techniques showed that FGLM appears to be an effective support template for nanoparticles. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Raman spectroscopy were used to characterize and determine the size, shape, and structure of nanoparticles and composites. The TEM study characterized the fused carbon backbone as it began to take on a rounder shape. The TEM images also revealed that the average diameter of the gold nanoparticle was roughly 23 nm. The FTIR study confirmed O-H, C-C, and C=O as functional groups in the materials. The EDS analysis showed that the composite contained approximately 6.3% gold by weight. The crystal structures of FGLM and AuFGLM were identified via P-XRD analysis. Various reaction conditions were used to test the catalytic ability of AuFGLM, including various solution pHs, temperatures, and doses of NaBH 4 . It was observed that optimal reaction conditions included high temperature, an acidic solution pH, and a higher dose of NaBH 4 . The activation energy of the reaction was determined to be 45.5 kJ mol -1 , and it was found that the catalyst could be used multiple times in a row with an increased volume of hydrogen produced in ensuing trials. The activation energy of this novel catalyst is competitive compared to similar catalysts and its ability to produce hydrogen over multiple uses makes the material an exciting choice for catalyzing the hydrolysis of NaBH 4 for use as a hydrogen fuel source.

08 HYDROGEN↗
DOE OSTI2019

World's Finest Gold Specimen Probed With Los Alamos Neutrons

Using neutron characterization techniques a team of scientists have peered inside one of the most unique examples of wire gold, understanding for the first time the specimen's structure and possible formation process. The 263 gram, 12 centimeter tall specimen, known as the Ram's Horn, belongs to the collection of the Mineralogical and Geological Museum Harvard University (MGMH). "Almost nothing other than the existence of the specimen is known about wire gold," said Sven Vogel, a physicist at Los Alamos National Laboratory's neutron science center, LANSCE, a half-mile-long particle accelerator that provides high- and low-energy protons and neutrons for a wide variety of scientific research. Found in 1887 at the Ground Hog Mine in Red Cliff, Colorado, mysteriously shaped like a twisted bunch of wires instead of the more recognizable golden nugget, the Ram's Horn has baffled mineralogists since its discovery. The unknown: what is its fundamental structure and how did it form? "Some native metals, a metal or metal alloy found in nature can occur in what is called wire morphology," said John Rakovan, Professor of Mineralogy at Miami University in Ohio. "Much more common in silver, the wire morphology is rarely seen in gold samples and this specimen is without question the finest known example."

58 GEOSCIENCES↗
DOE OSTI2017

Selective C−H Bond Cleavage in Methane by Small Gold Clusters

Abstract Methane represents the major constituent of natural gas. It is primarily used only as a source of energy by means of combustion, but could also serve as an abundant hydrocarbon feedstock for high quality chemicals. One of the major challenges in catalysis research nowadays is therefore the development of materials that selectively cleave one of the four C−H bonds of methane and thus make it amenable for further chemical conversion into valuable compounds. By employing infrared spectroscopy and first‐principles calculations it is uncovered herein that the interaction of methane with small gold cluster cations leads to selective C−H bond dissociation and the formation of hydrido methyl complexes, H‐Au x + ‐CH 3 . The distinctive selectivity offered by these gold clusters originates from a fine interplay between the closed‐shell nature of the d states and relativistic effects in gold. Such fine balance in fundamental interactions could prove to be a tunable feature in the rational design of a catalyst.

Lang, Sandra M.↗
DOE OSTI2018

Exploring the Effect of Gold Support on the Oxygen Reduction Reaction Activity of Metal Porphycenes

It has been a long-standing goal to find alternative, cost effective catalysts for oxygen reduction reaction (ORR) in fuel cells. Molecular complexes capable of efficiently catalyzing ORR, when supported on a conducting solid surface could provide interesting hybrid materials combining the best of homogeneous and heterogeneous catalysis. Here, we utilize density functional theory to study the ORR activity of molecular (unsupported) and gold supported 3d metal (II)-porphycenes (MPc). All the 3d metal-porphycenes adsorb strongly on the Au(111) support with negative free energy of formation ranging from 1.0–3.0 eV while solvation lowers the energy of molecular MPc by only 0.5 eV compared to the gas phase. These indicate that the 3d MPc are stable and anchored firmly to the gold surface under ORR conditions. Based on our analysis, the gold support enhances the ORR activity in some of the examined MPc systems. We find that the molecular MnPc and FePc are the best ORR electrocatalysts with theoretical overpotentials of 0.44 V and 0.36 V. Thus, this work highlights the important role of the support in preserving/increasing the activity of molecular catalyst.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

In situ SEM and ToF-SIMS analysis of IgG conjugated gold nanoparticles at aqueous surfaces

In this study, we report new results of in situ study of 5 nm goat anti-mouse IgG gold nanoparticles in a novel portable vacuum compatible microfluidic device using scanning electron microscope (SEM) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The unique feature of the liquid flow cell is that the detection window is open to the vacuum allowing direct probing of the liquid surface. The flow cell is composed of a silicon nitride (SiN) membrane and polydimethylsiloxane (PDMS), and it is fully compatible with vacuum operations for surface analysis. The aperture can be drilled through the 100 nm SiN membrane using a focused ion beam. Characteristic signals of the conjugated gold nanoparticles were successfully observed through the aperture by both energy-dispersive X-ray spectroscopy (EDX) in SEM and ToF-SIMS. Comparison was also made among wet samples, dry samples, and liquid sample in the flow cell using SEM/EDX. Stronger gold signal can be observed in our novel portable device by SEM/EDX compared with the wet or dry samples, respectively. Our results indicate that analyses of the nanoparticle components are better made in their native liquid environment. This is made possible using our unique microfluidic flow cell.

aqueous surface↗
DOE OSTI2017

Photoluminescence Enhancement of CuInS 2 Quantum Dots in Solution Coupled to Plasmonic Gold Nanocup Array

A strong plasmonic enhancement of photoluminescence (PL) decay rate in quantum dots (QDs) coupled to an array of gold-coated nanocups is demonstrated. CuInS2 QDs that emit at a wavelength that overlaps with the extraordinary optical transmission (EOT) of the gold nanocup array are placed in the cups as solutions. Time-resolved PL reveals that the decay rate of the QDs in the plasmonically coupled system can be enhanced by more than an order of magnitude. Using finite-difference time-domain (FDTD) simulations, it is shown that this enhancement in PL decay rate results from an enhancement factor of ≈100 in electric field intensity provided by the plasmonic mode of the nanocup array, which is also responsible for the EOT. The simulated Purcell factor approaches 86 at the bottom of the nanocup and is ≈3–15 averaged over the nanocup cavity height, agreeing with the experimental enhancement result. In conclusion, this demonstration of solution-based coupling between QDs and gold nanocups opens up new possibilities for applications that would benefit from a solution environment such as biosensing.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Mechanically Assisted Self‐Healing of Ultrathin Gold Nanowires

Abstract As the critical feature sizes of integrated circuits approaching sub‐10 nm, ultrathin gold nanowires (diameter <10 nm) have emerged as one of the most promising candidates for next‐generation interconnects in nanoelectronics. Also due to their ultrasmall dimensions, however, the structures and morphologies of ultrathin gold nanowires are more prone to be damaged during practical services, for example, Rayleigh instability can significantly alter their morphologies upon Joule heating, hindering their applications as interconnects. Here, it is shown that upon mechanical perturbations, predamaged, nonuniform ultrathin gold nanowires can quickly recover into uniform diameters and restore their smooth surfaces, via a simple mechanically assisted self‐healing process. By examining the local self‐healing process through in situ high‐resolution transmission electron microscopy, the underlying mechanism is believed to be associated with surface atomic diffusion as evidenced by molecular dynamics simulations. In addition, mechanical manipulation can assist the atoms to overcome the diffusion barriers, as suggested by ab initio calculations, to activate more surface adatoms to diffuse and consequently speed up the self‐healing process. This result can provide a facile method to repair ultrathin metallic nanowires directly in functional devices, and quickly restore their microstructures and morphologies by simple global mechanical perturbations.

Wang, Binjun↗
DOE OSTI2018

Diphosphine-induced chiral propeller arrangement of gold nanoclusters for singlet oxygen photogeneration

In this study, 1,2-bis(diphenylphosphino)ethane (dppe) ligands are used to synthesize gold nanoclusters with an icosahedral Au 13 core. The nanoclusters are characterized and formulated as [Au 13 (dppe) 5 Cl 2 ]Cl 3 using synchrotron radiation X-ray diffraction, UV/Vis absorption spectroscopy, electrospray ionization mass spectrometry, and density functional theory (DFT) calculations. The bidentate feature of dppe ligands and the positions of coordinating surface gold atoms induce a helical arrangement that forms a propeller-like structure, which reduces the symmetry of the gold nanocluster to C 1 . Therefore, dppe ligands perform as a directing agent to create chiral an ansa metallamacrocycle [Au 13 (dppe) 5 Cl 2 ] 3+ nanocluster, as confirmed by simulated electronic circular dichroism spectrum. The highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) gap of the [Au 13 (dppe) 5 Cl 2 ] 3+ cluster is determined as approx. 1.9 eV, and further confirmed by ultraviolet photoemission spectroscopy analysis and DFT simulation. Furthermore, the photoactivity of [Au 13 (dppe) 5 Cl 2 ] 3+ is investigated, with the nanocluster shown to possess near-infrared photoluminescence properties, which can be employed for 1 O 2 photogeneration. In conclusion, the quantum yield of 1 O 2 photogeneration using the [Au 13 (dppe) 5 Cl 2 ] 3+ nanocluster is up to 0.71, which is considerably higher than those of anthracene (an organic dye), and Au 25 and Au 38 nanoclusters.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Indirect electrochemical method for high accuracy quantification of protein adsorption on gold surfaces

We demonstrate the use of copper underpotential deposition (UPD) for measurement of the electrochemically active surface area of a protein-modified gold electrode. The kinetics of adsorption and the subsequent structural rearrangement of β-casein, as a model protein, on the surface of a gold electrode have been followed over time. The protein-free surface area was determined by measuring the charge derived from UPD copper deposition on the non-blocked surface area at different stages of adsorption. The behaviour of β-casein adsorption as a function of surface roughness and the microstructure of the gold electrode, as well as the concentration of the protein solution, are studied using this method.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Homogeneous Gold Redox Chemistry: Organometallics, Catalysis, and Beyond

Gold redox chemistry holds the promise of unique reactivities and selectivities that are different to other transition metals. Recent studies have utilized strain release, ligand design, and photochemistry to promote the otherwise sluggish oxidative addition to Au(I) complexes. More details on the reductive elimination from Au(III) complexes have also been revealed. These discoveries have facilitated the development of gold redox catalysis and will continue to offer mechanistic insight and inspiration for other transition metals. Furthermore, this review highlights how research in organometallic chemistry has led to gold redox catalysis, as well as applications in materials science, bioconjugation, and radiochemical synthesis.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

A Comparison of Single-Molecule Emission in Aluminum and Gold Zero-Mode Waveguides

We characterized the effect of gold and aluminum zero-mode waveguides (ZMWs) on the brightness of immobilized single emitters by probing fluorophores that absorb in the green and red regions of the visible spectrum. Aluminum ZMWs enhance the emission of Atto565 fluorophores upon green excitation, but they do not enhance the emission of Atto647N fluorophores upon red excitation. Gold ZMWs increase emission of both fluorophores with Atto647N showing enhancement that is threefold higher than that observed for Atto565. Our work indicates that 200 nm gold ZMWs are better suited for single-molecule fluorescence studies in the red region of the visible spectrum, while aluminum appears more suited for the green region of the visible spectrum.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Probing Biomolecular Interactions with Gold Nanoparticle-Decorated Single-Walled Carbon Nanotubes

Hybrid nanomaterials comprising metal–graphitic interfaces are uniquely suitable to probe molecular interactions and the associated phenomena such as charge transfer and adsorbate spillover effects. In this paper, we study the modulation of the electronic and chemical properties of gold nanoparticle-decorated single-walled carbon nanotubes (SWCNT) using Raman spectroscopy and measurements of field-effect transistor (FET) characteristics. SWCNT are extremely sensitive to changes in the local electronic environment and therefore gold-analyte interactions may be probed both through changes in FET characteristics (as an electrical transducer) and in surface-enhanced Raman scattering (as a chromophore). We study these changes both experimentally and theoretically in order to elucidate the electronic structure of complex nanocomposites, and the information gathered from these experiments is applied to the study of biomolecular interactions with gold nanoparticle-decorated SWCNT. Lastly, this study, in addition to providing deeper understanding of metal–graphitic interfaces, will offer a combined approach to SWCNT biosensing methodology based on the dual monitoring of the FET–Raman characteristics, which we demonstrate through detection of glutathione.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Electron–Hole-Pair-Induced Vibrational Energy Relaxation of Rhenium Catalysts on Gold Surfaces

A combination of time-resolved vibrational spectroscopy and density functional theory techniques have been applied to study the vibrational energy relaxation dynamics of the Re(4,4'-dicyano-2,2'-bipyridine)(CO)3Cl (Re(CO)3Cl) catalyst for CO2 to CO conversion bound to gold surfaces. The kinetics of vibrational relaxation exhibits a biexponential decay including an ultrafast initial relaxation and complete recovery of the ground vibrational state. Ab initio molecular dynamics simulations and time-dependent perturbation theory reveal the former to be due to vibrational population exchange between CO stretching modes and the latter to be a combination of intramolecular vibrational relaxation (IVR) and electron–hole pair (EHP)-induced energy transfer into the gold substrate. EHP-induced energy transfer from the Re(CO)3Cl adsorbate into the gold surface occurs on the same time scale as IVR of Re(CO)3Cl in aprotic solvents. Therefore, it is expected to be particularly relevant to understanding the reduced catalytic activity of the homogeneous catalyst when anchored to a metal surface.

Ge, Aimin↗