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Sample records for implanted metal nanoparticles

  1. The formation of silver metal nanoparticles by ion implantation in silicate glasses

    NASA Astrophysics Data System (ADS)

    Vytykacova, S.; Svecova, B.; Nekvindova, P.; Spirkova, J.; Mackova, A.; Miksova, R.; Böttger, R.

    2016-03-01

    It has been shown that glasses containing silver metal nanoparticles are promising photonics materials for the fabrication of all-optical components. The resulting optical properties of the nanocomposite glasses depend on the composition and structure of the glass, as well as on the type of metal ion implanted and the experimental procedures involved. The main aim of this article was to study the influence of the conditions of the ion implantation and the composition of the glass on the formation of metal nanoparticles in such glasses. Four various types of silicate glasses were implanted with Ag+ ions with different energy (330 keV, 1.2 MeV and 1.7 MeV), with the fluence being kept constant (1 × 1016 ions cm-2). The as-implanted samples were annealed at 600 °C for 1 h. The samples were characterised in terms of: the nucleation of metal nanoparticles (linear optical absorption), the migration of silver through the glass matrix during the implantation and post-implantation annealing (Rutherford backscattering spectroscopy), and the oxidation state of silver (photoluminescence in the visible region).

  2. Silver nanoparticles and growth factors incorporated hydroxyapatite coatings on metallic implant surfaces for enhancement of osteoinductivity and antibacterial properties.

    PubMed

    Xie, Chao-Ming; Lu, Xiong; Wang, Ke-Feng; Meng, Fan-Zhi; Jiang, Ou; Zhang, Hong-Ping; Zhi, Wei; Fang, Li-Ming

    2014-06-11

    Research on incorporation of both growth factors and silver (Ag) into hydroxyapatite (HA) coatings on metallic implant surfaces for enhancing osteoinductivity and antibacterial properties is a challenging work. Generally, Ag nanoparticles are easy to agglomerate and lead to a large increase in local Ag concentration, which could potentially affect cell activity. On the other hand, growth factors immobilization requires mild processing conditions so as to maintain their activities. In this study, bone morphology protein-2 (BMP-2) and Ag nanoparticle contained HA coatings were prepared on Ti surfaces by combining electrochemical deposition (ED) of Ag and electrostatic immobilization of BMP-2. During the ED process, chitosan (CS) was selected as the stabilizing agent to chelate Ag ions and generate Ag nanoparticles that are uniformly distributed in the coatings. CS also reduces Ag toxicity while retaining its antibacterial activity. Afterwards, a BMP/heparin solution was absorbed on the CS/Ag/HA coatings. Consequently, BMP-2 was immobilized on the coatings by the electrostatic attraction between CS, heparin, and BMP-2. Sustained release of BMP-2 and Ag ions from HA coatings was successfully demonstrated for a long period. Results of antibacterial tests indicate that the CS/Ag/HA coatings have high antibacterial properties against both Staphylococcus epidermidis and Escherichia coli. Osteoblasts (OB) culture reveals that the CS/Ag/HA coatings exhibit good biocompatibility. Bone marrow stromal cells (BMSCs) culture indicates that the BMP/CS/Ag/HA coatings have good osteoinductivity and promote the differentiation of BMSCs. Ti bars with BMP/CS/Ag/HA coatings were implanted into the femur of rabbits to evaluate the osteoinductivity of the coatings. Results indicate that BMP/CS/Ag/HA coatings favor bone formation in vivo. In summary, this study presents a convenient and effective method for the incorporation of growth factors and antibacterial agents into HA coatings. This

  3. High-dose boron and silver ion implantation into PMMA probed by slow positrons: Effects of carbonization and formation of metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Kavetskyy, T.; Iida, K.; Nagashima, Y.; Kuczumow, A.; Šauša, O.; Nuzhdin, V.; Valeev, V.; Stepanov, A. L.

    2017-01-01

    The Doppler broadening slow positron beam spectroscopy (SPBS) data for the previously observed effect of carbonization in high-dose (>1016 ion/cm2) 40 keV boron-ion-implanted polymethylmethacrylate (B:PMMA) and another one obtained for the effect of formation of metal nanoparticles in high-dose 30 keV silver-ion-implanted polymer (Ag:PMMA) are compared. Following to the Doppler broadening SPBS results, a difference in the high-dose ion-irradiation-induced processes in B:PMMA and Ag:PMMA is detected.

  4. Preparation of bone-implants by coating hydroxyapatite nanoparticles on self-formed titanium dioxide thin-layers on titanium metal surfaces.

    PubMed

    Wijesinghe, W P S L; Mantilaka, M M M G P G; Chathuranga Senarathna, K G; Herath, H M T U; Premachandra, T N; Ranasinghe, C S K; Rajapakse, R P V J; Rajapakse, R M G; Edirisinghe, Mohan; Mahalingam, S; Bandara, I M C C D; Singh, Sanjleena

    2016-06-01

    Preparation of hydroxyapatite coated custom-made metallic bone-implants is very important for the replacement of injured bones of the body. Furthermore, these bone-implants are more stable under the corrosive environment of the body and biocompatible than bone-implants made up of pure metals and metal alloys. Herein, we describe a novel, simple and low-cost technique to prepare biocompatible hydroxyapatite coated titanium metal (TiM) implants through growth of self-formed TiO2 thin-layer (SFTL) on TiM via a heat treatment process. SFTL acts as a surface binder of HA nanoparticles in order to produce HA coated implants. Colloidal HA nanorods prepared by a novel surfactant-assisted synthesis method, have been coated on SFTL via atomized spray pyrolysis (ASP) technique. The corrosion behavior of the bare and surface-modified TiM (SMTiM) in a simulated body fluid (SBF) medium is also studied. The highest corrosion rate is found to be for the bare TiM plate, but the corrosion rate has been reduced with the heat-treatment of TiM due to the formation of SFTL. The lowest corrosion rate is recorded for the implant prepared by heat treatment of TiM at 700 °C. The HA-coating further assists in the passivation of the TiM in the SBF medium. Both SMTiM and HA coated SMTiM are noncytotoxic against osteoblast-like (HOS) cells and are in high-bioactivity. The overall production process of bone-implant described in this paper is in high economic value.

  5. Engineered porous metals for implants

    NASA Astrophysics Data System (ADS)

    Vamsi Krishna, B.; Xue, Weichang; Bose, Susmita; Bandyopadhyay, Amit

    2008-05-01

    Interest is significant in patient-specific implants with the possibility of guided tissue regeneration, particularly for load-bearing implants. For such implants to succeed, novel design approaches and fabrication technologies that can achieve balanced mechanical and functional performance in the implants are necessary. This article is focused on porous load-bearing implants with tailored micro-as well as macrostructures using laser-engineered net shaping (LENS™), a solid freeform fabrication or rapid prototyping technique that can be used to manufacture patient-specific implants. This review provides an insight into LENS, some properties of porous metals, and the potential applications of this process to fabricate unitized structures which can eliminate longstanding challenges in load-bearing implants to increase their in-vivo lifetime, such as in a total hip prosthesis.

  6. In situ fabrication of silver nanoparticle-filled hydrogen titanate nanotube layer on metallic titanium surface for bacteriostatic and biocompatible implantation.

    PubMed

    Wang, Zheng; Sun, Yan; Wang, Dongzhou; Liu, Hong; Boughton, Robert I

    2013-01-01

    A silver nanoparticle (AgNP)-filled hydrogen titanate nanotube layer was synthesized in situ on a metallic titanium substrate. In the synthesis approach, a layer of sodium titanate nanotubes is first prepared on the titanium surface by using a hydrothermal method. Silver nitrate solution is absorbed into the nanotube channels by immersing a dried nanotube layer in silver nitrate solution. Finally, silver ions are reduced by glucose, leading to the in situ growth of AgNPs in the hydrogen titanate nanotube channels. Long-term silver release and bactericidal experiments demonstrated that the effective silver release and effective antibacterial period of the titanium foil with a AgNP-filled hydrogen titanate nanotube layer on the surface can extend to more than 15 days. This steady and prolonged release characteristic is helpful to promote a long-lasting antibacterial capability for the prevention of severe infection after surgery. A series of antimicrobial and biocompatible tests have shown that the sandwich nanostructure with a low level of silver loading exhibits a bacteriostatic rate as high as 99.99%, while retaining low toxicity for cells and possessing high osteogenic potential. Titanium foil with a AgNP-filled hydrogen titanate nanotube layer on the surface that is fabricated with low-cost surface modification methods is a promising implantable material that will find applications in artificial bones, joints, and dental implants.

  7. Virus templated metallic nanoparticles

    NASA Astrophysics Data System (ADS)

    Aljabali, Alaa A. A.; Barclay, J. Elaine; Lomonossoff, George P.; Evans, David J.

    2010-12-01

    Plant viruses are considered as nanobuilding blocks that can be used as synthons or templates for novel materials. Cowpea mosaic virus (CPMV) particles have been shown to template the fabrication of metallic nanoparticles by an electroless deposition metallization process. Palladium ions were electrostatically bound to the virus capsid and, when reduced, acted as nucleation sites for the subsequent metal deposition from solution. The method, although simple, produced highly monodisperse metallic nanoparticles with a diameter of ca. <=35 nm. CPMV-templated particles were prepared with cobalt, nickel, iron, platinum, cobalt-platinum and nickel-iron.Plant viruses are considered as nanobuilding blocks that can be used as synthons or templates for novel materials. Cowpea mosaic virus (CPMV) particles have been shown to template the fabrication of metallic nanoparticles by an electroless deposition metallization process. Palladium ions were electrostatically bound to the virus capsid and, when reduced, acted as nucleation sites for the subsequent metal deposition from solution. The method, although simple, produced highly monodisperse metallic nanoparticles with a diameter of ca. <=35 nm. CPMV-templated particles were prepared with cobalt, nickel, iron, platinum, cobalt-platinum and nickel-iron. Electronic supplementary information (ESI) available: Additional experimental detail, agarose gel electrophoresis results, energy dispersive X-ray spectra, ζ-potential measurements, dynamic light scattering data, nanoparticle tracking analysis and an atomic force microscopy image of Ni-CPMV. See DOI: 10.1039/c0nr00525h

  8. Metallic magnetic nanoparticles.

    PubMed

    Hernando, A; Crespo, P; García, M A

    2005-12-22

    In this paper, we reviewed some relevant aspects of the magnetic properties of metallic nanoparticles with small size (below 4 nm), covering the size effects in nanoparticles of magnetic materials, as well as the appearance of magnetism at the nanoscale in materials that are nonferromagnetic in bulk. These results are distributed along the text that has been organized around three important items: fundamental magnetic properties, different fabrication procedures, and characterization techniques. A general introduction and some experimental results recently obtained in Pd and Au nanoparticles have also been included. Finally, the more promising applications of magnetic nanoparticles in biomedicine are indicated. Special care was taken to complete the literature available on the subject.

  9. Combining dissimilar metals in orthopaedic implants: revisited.

    PubMed

    Zartman, Kevin C; Berlet, Gregory C; Hyer, Christopher F; Woodard, Joseph R

    2011-10-01

    The use of metals as implant materials has become common practice in the field of orthopaedics. A wide variety of conditions are treated with metallic implants, and designers have used an assortment of materials to meet the unique mechanical demands of each application. The majority of implants used today, whether pins, plates, screws, or total joints, are made of cobalt-chrome alloy, stainless steel, or titanium. Common metallurgic wisdom cautions against bonding dissimilar metals in a biologically active environment. Surgeons have therefore shied away from combining dissimilar metal implants because of the fear of inciting corrosion that could potentially compromise the implants and lead to aseptic loosening, implant failure, or adverse biological reaction in host tissue. As surgical reconstruction and arthroplasty options expand with the advent of newer implants and expanded operative techniques, the orthopaedic surgeon will increasingly be faced with weighing the risks and benefits of combining implants made of dissimilar metals in a patient. Here, the authors examine the origins of the concern over using mixed metals, discuss mechanisms of corrosion as they relate to surgical implants, and review both in vitro and in vivo studies concerning the most common combinations of dissimilar metals in order to guide the surgeon in choosing implants.

  10. Method for producing metallic nanoparticles

    DOEpatents

    Phillips, Jonathan; Perry, William L.; Kroenke, William J.

    2004-02-10

    Method for producing metallic nanoparticles. The method includes generating an aerosol of solid metallic microparticles, generating non-oxidizing plasma with a plasma hot zone at a temperature sufficiently high to vaporize the microparticles into metal vapor, and directing the aerosol into the hot zone of the plasma. The microparticles vaporize in the hot zone to metal vapor. The metal vapor is directed away from the hot zone and to the plasma afterglow where it cools and condenses to form solid metallic nanoparticles.

  11. Information for Patients Who Have Metal-on-Metal Hip Implants

    MedlinePlus

    ... Metal Hip Implants Information for Patients Who Have Metal-on-Metal Hip Implants Share Tweet Linkedin Pin it More ... How do I know if I have a metal-on-metal hip implant? Patients are usually told ...

  12. Prosthetic metal implants and airport metal detectors

    PubMed Central

    Dancey, A; Titley, OG

    2013-01-01

    Introduction Metal detectors have been present in airports and points of departure for some time. With the introduction of heightened security measures in response to fears of an increased threat of terrorism, they may become more prevalent in other public locations. The aim of this study was to ascertain which prosthetic devices activated metal detector devices used for security purposes. Methods A range of prosthetic devices used commonly in orthopaedic and plastic surgery procedures were passed through an arch metal detector at Birmingham Airport in the UK. Additionally, each item was passed under a wand detector. Items tested included expandable breast prostheses, plates used in wrist and hand surgery, screws, K-wires, Autosuture™ ligation clips and staples. Results No prostheses were detected by the arch detector. The expandable implants and wrist plates were the only devices detected by passing the wand directly over them. No device was detected by the wand when it was under cover of the axillary soft tissue. Screws, K-wires, Autosuture™ clips and staples were not detected under any of the study conditions. Conclusions Although unlikely to trigger a detector, it is possible that an expandable breast prosthesis or larger plate may do so. It is therefore best to warn patients of this so they can anticipate detection and further examination. PMID:23827294

  13. Fabrication of Metallic Hollow Nanoparticles

    NASA Technical Reports Server (NTRS)

    Kim, Jae-Woo (Inventor); Choi, Sr., Sang H. (Inventor); Lillehei, Peter T. (Inventor); Chu, Sang-Hyon (Inventor); Park, Yeonjoon (Inventor); King, Glen C. (Inventor); Elliott, James R. (Inventor)

    2016-01-01

    Metal and semiconductor nanoshells, particularly transition metal nanoshells, are fabricated using dendrimer molecules. Metallic colloids, metallic ions or semiconductors are attached to amine groups on the dendrimer surface in stabilized solution for the surface seeding method and the surface seedless method, respectively. Subsequently, the process is repeated with additional metallic ions or semiconductor, a stabilizer, and NaBH.sub.4 to increase the wall thickness of the metallic or semiconductor lining on the dendrimer surface. Metallic or semiconductor ions are automatically reduced on the metallic or semiconductor nanoparticles causing the formation of hollow metallic or semiconductor nanoparticles. The void size of the formed hollow nanoparticles depends on the dendrimer generation. The thickness of the metallic or semiconductor thin film around the dendrimer depends on the repetition times and the size of initial metallic or semiconductor seeds.

  14. Metallic nanoparticles meet metadynamics

    NASA Astrophysics Data System (ADS)

    Pavan, L.; Rossi, K.; Baletto, F.

    2015-11-01

    Metadynamics coupled with classical molecular dynamics has been successfully applied to sample the configuration space of metallic and bimetallic nanoclusters. We implement a new set of collective variables related to the pair distance distribution function of the nanoparticle to achieve an exhaustive isomer sampling. As paradigmatic examples, we apply our methodology to Ag147, Pt147, and their alloy AgshellPtcore at 2:1 and 1:1 chemical compositions. The proposed scheme is able to reproduce the known solid-solid structural transformation pathways, based on the Lipscomb's diamond-square-diamond mechanisms, both in mono and bimetallic nanoparticles. A discussion of the free energy barriers involved in these processes is provided.

  15. Metal Nanoparticle Aerogel Composites

    NASA Technical Reports Server (NTRS)

    Smith, David D.; Sibille, Laurent; Ignont, Erica; Snow, Lanee; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    We have fabricated sol-gels containing gold and silver nanoparticles. Formation of an aerogel produces a blue shift in the surface plasmon resonance as a result of the decrease in the dielectric constant of the matrix upon supercritical extraction of the solvent. However, as a result of chemical interface damping this blue shift does not obey effective medium theories. Annealing the samples in a reducing atmosphere at 400 C eliminates this discrepancy and results in narrowing and further blue shifting of the plasmon resonance. Metal particle aggregation also results in a deviation from the predictions of effective medium theories, but can be controlled through careful handling and by avoiding the use of alcohol. By applying effective medium theories to the heterogeneous interlayer surrounding each metal particle, we extend the technique of immersion spectroscopy to inhomogeneous materials characterized by spatially dependent dielectric constants, such as aerogels. We demonstrate that the shift in the surface plasmon wavelength provides the average fractional composition of each component (air and silica) in this inhomogeneous layer, i.e. the porosity of the aerogel or equivalently, for these materials, the catalytic dispersion. Additionally, the kinetics suggest that collective particle interactions in coagulated metal clusters are perturbed during silica gelation resulting in a change in the aggregate geometry.

  16. Synthesis metal nanoparticle

    DOEpatents

    Bunge, Scott D.; Boyle, Timothy J.

    2005-08-16

    A method for providing an anhydrous route for the synthesis of amine capped coinage-metal (copper, silver, and gold) nanoparticles (NPs) using the coinage-metal mesityl (mesityl=C.sub.6 H.sub.2 (CH.sub.3).sub.3 -2,4,6) derivatives. In this method, a solution of (Cu(C.sub.6 H.sub.2 (CH.sub.3).sub.3).sub.5, (Ag(C.sub.6 H.sub.2 (CH.sub.3).sub.3).sub.4, or (Au(C.sub.6 H.sub.2 (CH.sub.3).sub.3).sub.5 is dissolved in a coordinating solvent, such as a primary, secondary, or tertiary amine; primary, secondary, or tertiary phosphine, or alkyl thiol, to produce a mesityl precursor solution. This solution is subsequently injected into an organic solvent that is heated to a temperature greater than approximately 100.degree. C. After washing with an organic solvent, such as an alcohol (including methanol, ethanol, propanol, and higher molecular-weight alcohols), oxide free coinage NP are prepared that could be extracted with a solvent, such as an aromatic solvent (including, for example, toluene, benzene, and pyridine) or an alkane (including, for example, pentane, hexane, and heptane). Characterization by UV-Vis spectroscopy and transmission electron microscopy showed that the NPs were approximately 9.2.+-.2.3 nm in size for Cu.degree., (no surface oxide present), approximately 8.5.+-.1.1 nm Ag.degree. spheres, and approximately 8-80 nm for Au.degree..

  17. Broadband luminescence of Cu nanoparticles fabricated in SiO2 by ion implantation.

    PubMed

    Nguyen, Truong Khang; Le, Khai Q; Canimoglu, Adil; Can, Nurdogan

    2016-09-01

    In this study, we investigate optical properties of metal nanoparticle crystals fabricated by implanting copper (Cu) ions into single silica (SiO2) crystals with 400keV at various ion doses. The Cu implanted SiO2 (SiO2:Cu) crystal produces a broadband luminescence emission, ranging from blue to yellow, and having a blue luminescence peak at 546nm. Such anomalous luminescence emission bands suggest that the ion implantation may give rise to aggregation of Cu nanoparticles in the host matrix. The boundary element method-based modelling of a given Cu nanoparticle aggregation was employed to justify the broadband luminescence emission. Formation of Cu nanoparticles in SiO2 is predicted through their optical absorption data. The experimental results are compared with results of Mie calculations and we observe that the higher ion dose produces the larger particle size.

  18. Nanostructures from hydrogen implantation of metals.

    SciTech Connect

    McWatters, Bruce Ray; Causey, Rion A.; DePuit, Ryan J.; Yang, Nancy Y. C.; Ong, Markus D.

    2009-09-01

    This study investigates a pathway to nanoporous structures created by hydrogen implantation in aluminum. Previous experiments for fusion applications have indicated that hydrogen and helium ion implantations are capable of producing bicontinuous nanoporous structures in a variety of metals. This study focuses specifically on hydrogen and helium implantations of aluminum, including complementary experimental results and computational modeling of this system. Experimental results show the evolution of the surface morphology as the hydrogen ion fluence increases from 10{sup 17} cm{sup -2} to 10{sup 18} cm{sup -2}. Implantations of helium at a fluence of 10{sup 18} cm{sup -2} produce porosity on the order of 10 nm. Computational modeling demonstrates the formation of alanes, their desorption, and the resulting etching of aluminum surfaces that likely drives the nanostructures that form in the presence of hydrogen.

  19. Comparative study of metal and non-metal ion implantation in polymers: Optical and electrical properties

    NASA Astrophysics Data System (ADS)

    Resta, V.; Quarta, G.; Farella, I.; Maruccio, L.; Cola, A.; Calcagnile, L.

    2014-07-01

    The implantation of 1 MeV metal (63Cu+, 107Ag+, 197Au+) and non-metal (4He+, 12C+) ions in a polycarbonate (PC) matrix has been studied in order to evaluate the role of ion species in the modification of optical and electrical properties of the polymer. When the ion fluence is above ∼1 × 1013 ions cm-2, the threshold for latent tracks overlapping is overcome and π-bonded carbon clusters grow and aggregate forming a network of conjugated Cdbnd C bonds. For fluences around 1 × 1017 ions cm-2, the aggregation phenomena induce the formation of amorphous carbon and/or graphite like structures. At the same time, nucleation of metal nanoparticles (NPs) from implanted species can take place when the supersaturation threshold is overcome. The optical absorption of the samples increases in the visible range and the optical band gap redshifts from 3.40 eV up to 0.70 eV mostly due to the carbonization process and the formation of C0x clusters and cluster aggregates. Specific structures in the extinction spectra are observed when metal ions are selected in contrast to the non-metal ion implanted PC, thus revealing the possible presence of noble metal based NPs interstitial to the C0x cluster network. The corresponding electrical resistance decreases much more when metal ions are implanted with at least a factor of 2 orders of magnitude difference than the non-metal ions based samples. An absolute value of ∼107 Ω/sq has been measured for implantation with metals at doses higher than 5 × 1016 ions cm-2, being 1017 Ω/sq the corresponding sheet resistance for pristine PC.

  20. Antimicrobial polymers with metal nanoparticles.

    PubMed

    Palza, Humberto

    2015-01-19

    Metals, such as copper and silver, can be extremely toxic to bacteria at exceptionally low concentrations. Because of this biocidal activity, metals have been widely used as antimicrobial agents in a multitude of applications related with agriculture, healthcare, and the industry in general. Unlike other antimicrobial agents, metals are stable under conditions currently found in the industry allowing their use as additives. Today these metal based additives are found as: particles, ions absorbed/exchanged in different carriers, salts, hybrid structures, etc. One recent route to further extend the antimicrobial applications of these metals is by their incorporation as nanoparticles into polymer matrices. These polymer/metal nanocomposites can be prepared by several routes such as in situ synthesis of the nanoparticle within a hydrogel or direct addition of the metal nanofiller into a thermoplastic matrix. The objective of the present review is to show examples of polymer/metal composites designed to have antimicrobial activities, with a special focus on copper and silver metal nanoparticles and their mechanisms.

  1. Antimicrobial Polymers with Metal Nanoparticles

    PubMed Central

    Palza, Humberto

    2015-01-01

    Metals, such as copper and silver, can be extremely toxic to bacteria at exceptionally low concentrations. Because of this biocidal activity, metals have been widely used as antimicrobial agents in a multitude of applications related with agriculture, healthcare, and the industry in general. Unlike other antimicrobial agents, metals are stable under conditions currently found in the industry allowing their use as additives. Today these metal based additives are found as: particles, ions absorbed/exchanged in different carriers, salts, hybrid structures, etc. One recent route to further extend the antimicrobial applications of these metals is by their incorporation as nanoparticles into polymer matrices. These polymer/metal nanocomposites can be prepared by several routes such as in situ synthesis of the nanoparticle within a hydrogel or direct addition of the metal nanofiller into a thermoplastic matrix. The objective of the present review is to show examples of polymer/metal composites designed to have antimicrobial activities, with a special focus on copper and silver metal nanoparticles and their mechanisms. PMID:25607734

  2. Preparation of uniform nanoparticles of ultra-high purity metal oxides, mixed metal oxides, metals, and metal alloys

    DOEpatents

    Woodfield, Brian F.; Liu, Shengfeng; Boerio-Goates, Juliana; Liu, Qingyuan; Smith, Stacey Janel

    2012-07-03

    In preferred embodiments, metal nanoparticles, mixed-metal (alloy) nanoparticles, metal oxide nanoparticles and mixed-metal oxide nanoparticles are provided. According to embodiments, the nanoparticles may possess narrow size distributions and high purities. In certain preferred embodiments, methods of preparing metal nanoparticles, mixed-metal nanoparticles, metal oxide nanoparticles and mixed-metal nanoparticles are provided. These methods may provide tight control of particle size, size distribution, and oxidation state. Other preferred embodiments relate to a precursor material that may be used to form nanoparticles. In addition, products prepared from such nanoparticles are disclosed.

  3. Optical Properties of Metallic Nanoparticles

    NASA Astrophysics Data System (ADS)

    Vallée, F.

    The bright and changing colours obtained by dispersing metallic compounds in a glass matrix have been known empirically for centuries. Indeed, glasses have been coloured in the bulk by inclusion of metallic powders since ancient times to make jewellery and ornaments (see Chap. 25). Then in the Middle Ages, they were used for stained glass windows and later on for coloured glass artefacts, e.g., ruby red glass objects. However, the role played by nanoparticles in this colouring effect, i.e., the effects of nanoparticles on optical properties, were only first studied scientifically in the nineteenth century, by Michael Faraday [1].

  4. Tantalum—A bioactive metal for implants

    NASA Astrophysics Data System (ADS)

    Balla, Vamsi Krishna; Bose, Susmita; Davies, Neal M.; Bandyopadhyay, Amit

    2010-07-01

    Metallic biomaterials currently in use for load-bearing orthopedic applications are mostly bioinert and therefore lack sufficient osseointegration. Although bioactive ceramics such as hydroxyapatite (HA) can spontaneously bond to living bone tissue, low fracture toughness of HA limits their use as a bone substitute for load-bearing applications. Surface modification techniques such as HA coating on metals are current options to improve osseointegration in load-bearing metal implants. Over the last few decades researchers have attempted to find a bioactive metal with high mechanical strength and excellent fatigue resistance that can bond chemically with surrounding bone for orthopedic applications. Recent in vitro, in vivo, and clinical studies demonstrated that tantalum is a promising metal that is bioactive. However, tantalum applications in biomedical devices have been limited by processing challenges rather than biological performances. In this article, we provide an overview of processing aspects and biological properties of tantalum for load-bearing orthopedic applications.

  5. Synthesis of noble metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Bahadory, Mozhgan

    Improved methods were developed for the synthesis of noble metal nanoparticles. Laboratory experiments were designed for introducing of nanotechnology into the undergraduate curriculum. An optimal set of conditions for the synthesis of clear yellow colloidal silver was investigated. Silver nanoparticles were obtained by borohydride reduction of silver nitrate, a method which produces particles with average size of 12+/-2 nm, determined by Transmission Electron Microscopy (TEM). The plasmon absorbance is at 397 nm and the peak width at half maximum (PWHM) is 70-75 nm. The relationship between aggregation and optical properties was determined along with a method to protect the particles using polyvinylpyrrolidone (PVP). A laboratory experiment was designed in which students synthesize yellow colloidal silver, estimate particle size using visible spectroscopy, and study aggregation effects. The synthesis of the less stable copper nanoparticles is more difficult because copper nanopaticles are easily oxidized. Four methods were used for the synthesis of copper nanoparticles, including chemical reduction with sodium borohydride, sodium borohydride with potassium iodide, isopropyl alcohol with cetyltrimethylammonium bormide (CTAB) and reducing sugars. The latter method was also the basis for an undergraduate laboratory experiment. For each reaction, the dependence of stability of the copper nanoparticles on reagent concentrations, additives, relative amounts of reactants, and temperature is explored. Atomic force microscopy (AFM), TEM and UV-Visible Spectroscopy were used to characterize the copper nanoparticles. A laboratory experiment to produce copper nanoparticles from household chemicals was developed.

  6. The effect of metallic implants on radiation therapy in spinal tumor patients with metallic spinal implants

    SciTech Connect

    Son, Seok Hyun; Kang, Young Nam; Ryu, Mi-Ryeong

    2012-04-01

    The aim of this study was to evaluate the effect of metallic implants on the dose calculation for radiation therapy in patients with metallic implants and to find a way to reduce the error of dose calculation. We made a phantom in which titanium implants were inserted into positions similar to the implant positions in spinal posterior/posterolateral fusion. We compared the calculated dose of the treatment planning systems with the measured dose in the treatment equipment. We used 3 kinds of computed tomography (CT) (kilovoltage CT, extended-scaled kilovoltage CT, and megavoltage CT) and 3 kinds of treatment equipment (ARTISTE, TomoTherapy Hi-Art, and Cyberknife). For measurement of doses, we used an ionization chamber and Gafchromic external beam therapy film. The absolute doses that were measured using an ionization chamber at the isocenter in the titanium phantom were on average 1.9% lower than those in the reference phantom (p = 0.002). There was no statistically significant difference according to the kinds of CT images, the treatment equipment, and the size of the targets. As the distance from the surface of the titanium implants became closer, the measured doses tended to decrease (p < 0.001), and this showed a statistically significant difference among the kinds of CT images: the effect of metallic implants was less in the megavoltage CT than in the kilovoltage CT or the extended-scaled kilovoltage CT. The error caused by the titanium implants was beyond a clinically acceptable range. To reduce the error of dose calculation, we suggest that the megavoltage CT be used for planning. In addition, it is necessary to consider the distance between the titanium implants and the targets or the organs at risk to prescribe the dose for the target and the dose constraint for the organs at risk.

  7. Bioactive glass coatings for orthopedic metallic implants

    SciTech Connect

    Lopez-Esteban, Sonia; Saiz, Eduardo; Fujino, Sigheru; Oku, Takeo; Suganuma, Katsuaki; Tomsia, Antoni P.

    2003-06-30

    The objective of this work is to develop bioactive glass coatings for metallic orthopedic implants. A new family of glasses in the SiO2-Na2O-K2O-CaO-MgO-P2O5 system has been synthesized and characterized. The glass properties (thermal expansion, softening and transformation temperatures, density and hardness) are in line with the predictions of established empirical models. The optimized firing conditions to fabricate coatings on Ti-based and Co-Cr alloys have been determined and related to the glass properties and the interfacial reactions. Excellent adhesion to alloys has been achieved through the formation of 100-200 nm thick interfacial layers (Ti5Si3 on Ti-based alloys and CrOx on Co-Cr). Finally, glass coatings, approximately 100 mu m thick, have been fabricated onto commercial Ti alloy-based dental implants.

  8. Metal nanoparticles for biodetection

    NASA Astrophysics Data System (ADS)

    Oldenburg, Steven; Mock, Jack; Glass, James R.; Asenjo, Ana B.; Genick, Christine C.; Smith, David R.; Schultz, David A.; Schultz, Sheldon

    2002-10-01

    The large scattering cross section of plasmon resonant gold and silver nanoparticles functionalized with the appropriate ligand allows for sensitive and specific detection of nucleic acids and proteins. By varying the size, shape, and material morphology populations with a specific peak plasmon resonance can be prepared. By varying the order and length of plasmon resonant bar segment in a composite nanowire one can obtain a large number of particle populations. Distinct populations can be used for labels for multiplexing or as a platform for biological assays. An larger number of color populations can be obtained with composite nanowires that are fabricated with various lengths of silver, gold, or nickel segments. The order and length of the different plasmon resonance rod segments can be used to uniquely identify a rod population allowing for a large degree of multiplexing within a single sample.

  9. Metal nanoparticle inks

    SciTech Connect

    Lewis, Jennifer A.; Ahn, Bok Yeop; Duoss, Eric B.

    2011-04-12

    Stabilized silver particles comprise particles comprising silver, a short-chain capping agent adsorbed on the particles, and a long-chain capping agent adsorbed on the particles. The short-chain capping agent is a first anionic polyelectrolyte having a molecular weight (Mw) of at most 10,000, and the long-chain capping agent is a second anionic polyelectrolyte having a molecular weight (Mw) of at least 25,000. The stabilized silver particles have a solid loading of metallic silver of at least 50 wt %.

  10. Metallic nano-particles for trapping light.

    PubMed

    Tang, Yongan; Vlahovic, Branislav

    2013-02-07

    We study metallic nano-particles for light trapping by investigating the optical absorption efficiency of the hydrogenated amorphous silicon thin film with and without metallic nano-particles on its top. The size and shape of these nano-particles are investigated as to their roles of light trapping: scattering light to the absorption medium and converting light to surface plasmons. The optical absorption enhancement in the red light region (e.g., 650nm) due to the light trapping of the metallic nano-particles is observed when a layer of metallic nano-particle array has certain structures. The investigation of the light with incident angles shows the importance of the coupling efficiency of light to surface plasmons in the metallic nano-particle light trapping. PACS: 73.20.Mf, 42.25.s, 88.40.hj.

  11. Environmentally friendly preparation of metal nanoparticles

    EPA Science Inventory

    The book chapter summarizes the “state of the art” in the exploitation of various environmentally-friendly synthesis approaches, reaction precursors and conditions to manufacture metal and metal oxide nanoparticles for a vast variety of purposes.

  12. Muscle atrophy and metal-on-metal hip implants

    PubMed Central

    Berber, Reshid; Khoo, Michael; Cook, Erica; Guppy, Andrew; Hua, Jia; Miles, Jonathan; Carrington, Richard; Skinner, John; Hart, Alister

    2015-01-01

    Background and purpose Muscle atrophy is seen in patients with metal-on-metal (MOM) hip implants, probably because of inflammatory destruction of the musculo-tendon junction. However, like pseudotumors, it is unclear when atrophy occurs and whether it progresses with time. Our objective was to determine whether muscle atrophy associated with MOM hip implants progresses with time. Patients and methods We retrospectively reviewed 74 hips in 56 patients (32 of them women) using serial MRI. Median age was 59 (23–83) years. The median time post-implantation was 83 (35–142) months, and the median interval between scans was 11 months. Hip muscles were scored using the Pfirrmann system. The mean scores for muscle atrophy were compared between the first and second MRI scans. Blood cobalt and chromium concentrations were determined. Results The median blood cobalt was 6.84 (0.24–90) ppb and median chromium level was 4.42 (0.20–45) ppb. The median Oxford hip score was 34 (5–48). The change in the gluteus minimus mean atrophy score between first and second MRI was 0.12 (p = 0.002). Mean change in the gluteus medius posterior portion (unaffected by surgical approach) was 0.08 (p = 0.01) and mean change in the inferior portion was 0.10 (p = 0.05). Mean pseudotumor grade increased by 0.18 (p = 0.02). Interpretation Worsening muscle atrophy and worsening pseudotumor grade occur over a 1-year period in a substantial proportion of patients with MOM hip implants. Serial MRI helps to identify those patients who are at risk of developing worsening soft-tissue pathology. These patients should be considered for revision surgery before irreversible muscle destruction occurs. PMID:25588091

  13. Mesoporous titanium dioxide coating for metallic implants.

    PubMed

    Xia, Wei; Grandfield, Kathryn; Hoess, Andreas; Ballo, Ahmed; Cai, Yanling; Engqvist, Håkan

    2012-01-01

    A bioactive mesoporous titanium dioxide (MT) coating for surface drug delivery has been investigated to develop a multifunctional implant coating, offering quick bone bonding and biological stability. An evaporation induced self-assembly (EISA) method was used to prepare a mesoporous titanium dioxide coating of the anatase phase with BET surface area of 172 m(2)/g and average pore diameter of 4.3 nm. Adhesion tests using the scratch method and an in situ screw-in/screw-out technique confirm that the MT coating bonds tightly with the metallic substrate, even after removal from bone. Because of its high surface area, the bioactivity of the MT coating is much better than that of a dense TiO(2) coating of the same composition. Quick formation of hydroxyapatite (HA) in vitro can be related to enhance bonding with bone. The uptake of antibiotics by the MT coating reached 13.4 mg/cm(3) within a 24 h loading process. A sustained release behavior has been obtained with a weak initial burst. By using Cephalothin as a model drug, drug loaded MT coating exhibits a sufficient antibacterial effect on the material surface, and within millimeters from material surface, against E.coli. Additionally, the coated and drug loaded surfaces showed no cytotoxic effect on cell cultures of the osteoblastic cell line MG-63. In conclusion, this study describes a novel, biocompatiblemesoporous implant coating, which has the ability to induce HA formation and could be used as a surface drug-delivery system.

  14. Method for producing metal oxide nanoparticles

    DOEpatents

    Phillips, Jonathan; Mendoza, Daniel; Chen, Chun-Ku

    2008-04-15

    Method for producing metal oxide nanoparticles. The method includes generating an aerosol of solid metallic microparticles, generating plasma with a plasma hot zone at a temperature sufficiently high to vaporize the microparticles into metal vapor, and directing the aerosol into the hot zone of the plasma. The microparticles vaporize in the hot zone into metal vapor. The metal vapor is directed away from the hot zone and into the cooler plasma afterglow where it oxidizes, cools and condenses to form solid metal oxide nanoparticles.

  15. Nanotubular surface modification of metallic implants via electrochemical anodization technique.

    PubMed

    Wang, Lu-Ning; Jin, Ming; Zheng, Yudong; Guan, Yueping; Lu, Xin; Luo, Jing-Li

    2014-01-01

    Due to increased awareness and interest in the biomedical implant field as a result of an aging population, research in the field of implantable devices has grown rapidly in the last few decades. Among the biomedical implants, metallic implant materials have been widely used to replace disordered bony tissues in orthopedic and orthodontic surgeries. The clinical success of implants is closely related to their early osseointegration (ie, the direct structural and functional connection between living bone and the surface of a load-bearing artificial implant), which relies heavily on the surface condition of the implant. Electrochemical techniques for modifying biomedical implants are relatively simple, cost-effective, and appropriate for implants with complex shapes. Recently, metal oxide nanotubular arrays via electrochemical anodization have become an attractive technique to build up on metallic implants to enhance the biocompatibility and bioactivity. This article will thoroughly review the relevance of electrochemical anodization techniques for the modification of metallic implant surfaces in nanoscale, and cover the electrochemical anodization techniques used in the development of the types of nanotubular/nanoporous modification achievable via electrochemical approaches, which hold tremendous potential for bio-implant applications. In vitro and in vivo studies using metallic oxide nanotubes are also presented, revealing the potential of nanotubes in biomedical applications. Finally, an outlook of future growth of research in metallic oxide nanotubular arrays is provided. This article will therefore provide researchers with an in-depth understanding of electrochemical anodization modification and provide guidance regarding the design and tuning of new materials to achieve a desired performance and reliable biocompatibility.

  16. Nanotubular surface modification of metallic implants via electrochemical anodization technique

    PubMed Central

    Wang, Lu-Ning; Jin, Ming; Zheng, Yudong; Guan, Yueping; Lu, Xin; Luo, Jing-Li

    2014-01-01

    Due to increased awareness and interest in the biomedical implant field as a result of an aging population, research in the field of implantable devices has grown rapidly in the last few decades. Among the biomedical implants, metallic implant materials have been widely used to replace disordered bony tissues in orthopedic and orthodontic surgeries. The clinical success of implants is closely related to their early osseointegration (ie, the direct structural and functional connection between living bone and the surface of a load-bearing artificial implant), which relies heavily on the surface condition of the implant. Electrochemical techniques for modifying biomedical implants are relatively simple, cost-effective, and appropriate for implants with complex shapes. Recently, metal oxide nanotubular arrays via electrochemical anodization have become an attractive technique to build up on metallic implants to enhance the biocompatibility and bioactivity. This article will thoroughly review the relevance of electrochemical anodization techniques for the modification of metallic implant surfaces in nanoscale, and cover the electrochemical anodization techniques used in the development of the types of nanotubular/nanoporous modification achievable via electrochemical approaches, which hold tremendous potential for bio-implant applications. In vitro and in vivo studies using metallic oxide nanotubes are also presented, revealing the potential of nanotubes in biomedical applications. Finally, an outlook of future growth of research in metallic oxide nanotubular arrays is provided. This article will therefore provide researchers with an in-depth understanding of electrochemical anodization modification and provide guidance regarding the design and tuning of new materials to achieve a desired performance and reliable biocompatibility. PMID:25258532

  17. Antimicrobial activity of nanoparticulate metal oxides against peri-implantitis pathogens.

    PubMed

    Vargas-Reus, Miguel A; Memarzadeh, Kaveh; Huang, Jie; Ren, Guogang G; Allaker, Robert P

    2012-08-01

    Dental plaque accumulation may result in peri-implantitis, an inflammatory process causing loss of supporting bone that may lead to dental implant failure. The antimicrobial activities of six metal and metal oxide nanoparticles and two of their composites against bacterial pathogens associated with peri-implantitis were examined under anaerobic conditions. The activities of nanoparticles of silver (Ag), cuprous oxide (Cu(2)O), cupric oxide (CuO), zinc oxide (ZnO), titanium dioxide (TiO(2)), tungsten oxide (WO(3)), Ag+CuO composite and Ag+ZnO composite were assessed by minimum inhibitory (bacteriostatic) concentration (MIC) and minimum bactericidal concentration (MBC) determination against Prevotella intermedia, Porphyromonas gingivalis, Fusobacterium nucleatum and Aggregatibacter actinomycetemcomitans. Time-kill assays were carried out to examine the dynamics of the antimicrobial activity with ZnO nanoparticles. MIC and MBC values were in the range of <100 μg/mL to 2500 μg/mL and <100 μg/mL to >2500 μg/mL, respectively. The activity of the nanoparticles tested in descending order was Ag>Ag+CuO>Cu(2)O>CuO>Ag+ZnO>ZnO>TiO(2)>WO(3). Time-kill assays with ZnO demonstrated a significant decrease in growth of all species tested within 4h, reaching 100% within 2h for P. gingivalis and within 3h for F. nucleatum and P. intermedia. Coating titanium surfaces of dental and orthopaedic implants with antimicrobial nanoparticles should lead to an increased rate of implant success.

  18. Metal-metal bonding using silver/copper nanoparticles

    NASA Astrophysics Data System (ADS)

    Kobayashi, Y.; Maeda, T.; Yasuda, Y.; Morita, T.

    2016-08-01

    A method for producing nanoparticles composed of silver and copper and a metal-metal bonding technique using the silver/copper nanoparticles are proposed. The method consists of three steps. First, copper oxide nanoparticles are produced by mixing Cu(NO3)2 aqueous solution and NaOH aqueous solution. Second, copper metal nanoparticles are fabricated by reducing the copper oxide nanoparticles with hydrazine in the presence of poly(vinylpyrrolidone) (PVP). Third, silver/copper nanoparticles are synthesized by reducing Ag+ ions with hydrazine in the presence of the copper metal nanoparticles. Initial concentrations in the final silver/copper particle colloid, composed of 0.0075 M Cu2+, 0.0025 M Ag+, 1.0 g/L PVP, and 0.6 M hydrazine, produced silver/copper nanoparticles with an average size of 49 nm and a crystal size of 16.8 nm. Discs of copper metal were successfully bonded by the silver/copper nanoparticles under annealing at 400 °C and pressurizing at 1.2 MPa for 5 min in not only hydrogen gas but also nitrogen gas. The shear force required to separate the bonded discs was 22.3 MPa for the hydrogen gas annealing and 14.9 MPa for the nitrogen gas annealing (namely, 66.8 % of that for hydrogen gas annealing).

  19. Physiologically important metal nanoparticles and their toxicity.

    PubMed

    Sengupta, Jayeeta; Ghosh, Sourav; Datta, Poulami; Gomes, Aparna; Gomes, Antony

    2014-01-01

    Nanotechnology has been setting benchmarks for the last two decades, but the origins of this technology reach back to ancient history. Today, nanoparticles of both metallic and non-metallic origin are under research and development for applications in various fields of biology/therapeutics. Physiologically important metals are of concern because they are compatible with the human system in terms of absorption, assimilation, excretion, and side effects. There are several physiologically inorganic metals that are present in the human body with a wide range of biological activities. Some of these metals are magnesium, chromium, manganese, iron, cobalt, copper, zinc, selenium and molybdenum. These metals are synthesized in the form of nanoparticles by different physical and chemical methods. Physiologically important nanoparticles are currently under investigation for their bio-medical applications as well as for therapeutics. Along with the applicative aspects of nanoparticles, another domain that is of great concern is the risk assessment of these nanoparticles to avoid unnecessary hazards. It has been seen that these nanoparticles have been shown to possess toxicity in biological systems. Conventional physical and chemical methods of metal nanoparticle synthesis may be one possible reason for nanoparticle toxicity that can be overcome by synthesis of nanoparticles from biological sources. This review is an attempt to establish metal nanoparticles of physiological importance to be the best candidates for future nanotechnological tools and medicines, owing to the acceptability and safety in the human body. This can only be successful if these particles are synthesized with a better biocompatibility and low or no toxicity.

  20. Metals for bone implants. Part 1. Powder metallurgy and implant rendering.

    PubMed

    Andani, Mohsen Taheri; Shayesteh Moghaddam, Narges; Haberland, Christoph; Dean, David; Miller, Michael J; Elahinia, Mohammad

    2014-10-01

    New metal alloys and metal fabrication strategies are likely to benefit future skeletal implant strategies. These metals and fabrication strategies were looked at from the point of view of standard-of-care implants for the mandible. These implants are used as part of the treatment for segmental resection due to oropharyngeal cancer, injury or correction of deformity due to pathology or congenital defect. The focus of this two-part review is the issues associated with the failure of existing mandibular implants that are due to mismatched material properties. Potential directions for future research are also studied. To mitigate these issues, the use of low-stiffness metallic alloys has been highlighted. To this end, the development, processing and biocompatibility of superelastic NiTi as well as resorbable magnesium-based alloys are discussed. Additionally, engineered porosity is reviewed as it can be an effective way of matching the stiffness of an implant with the surrounding tissue. These porosities and the overall geometry of the implant can be optimized for strain transduction and with a tailored stiffness profile. Rendering patient-specific, site-specific, morphology-specific and function-specific implants can now be achieved using these and other metals with bone-like material properties by additive manufacturing. The biocompatibility of implants prepared from superelastic and resorbable alloys is also reviewed.

  1. Optical Spectroscopy of Hybrid Semiconductor Quantum Dots and Metal Nanoparticles

    DTIC Science & Technology

    2014-11-07

    SECURITY CLASSIFICATION OF: Optical studies of semiconductor quantum dots (SQDs), metal nanoparticles (MNPs), and their hybrid nanomaterials are...Distribution Unlimited Final Report: Optical Spectroscopy of Hybrid Semiconductor Quantum Dots and Metal Nanoparticles The views, opinions and/or findings...Semiconductor Quantum Dots and Metal Nanoparticles Report Title Optical studies of semiconductor quantum dots (SQDs), metal nanoparticles (MNPs), and their

  2. Assembly of metals and nanoparticles into novel nanocomposite superstructures

    PubMed Central

    Xu, Jiaquan; Chen, Lianyi; Choi, Hongseok; Konish, Hiromi; Li, Xiaochun

    2013-01-01

    Controlled assembly of nanoscale objects into superstructures is of tremendous interests. Many approaches have been developed to fabricate organic-nanoparticle superstructures. However, effective fabrication of inorganic-nanoparticle superstructures (such as nanoparticles linked by metals) remains a difficult challenge. Here we show a novel, general method to assemble metals and nanoparticles rationally into nanocomposite superstructures. Novel metal-nanoparticle superstructures are achieved by self-assembly of liquid metals and nanoparticles in immiscible liquids driven by reduction of free energy. Superstructures with various architectures, such as metal-core/nanoparticle-shell, nanocomposite-core/nanoparticle-shell, network of metal-linked core/shell nanostructures, and network of metal-linked nanoparticles, were successfully fabricated by simply tuning the volume ratio between nanoparticles and liquid metals. Our approach provides a simple, general way for fabrication of numerous metal-nanoparticle superstructures and enables a rational design of these novel superstructures with desired architectures for exciting applications.

  3. Chemoelectronic circuits based on metal nanoparticles.

    PubMed

    Yan, Yong; Warren, Scott C; Fuller, Patrick; Grzybowski, Bartosz A

    2016-07-01

    To develop electronic devices with novel functionalities and applications, various non-silicon-based materials are currently being explored. Nanoparticles have unique characteristics due to their small size, which can impart functions that are distinct from those of their bulk counterparts. The use of semiconductor nanoparticles has already led to improvements in the efficiency of solar cells, the processability of transistors and the sensitivity of photodetectors, and the optical and catalytic properties of metal nanoparticles have led to similar advances in plasmonics and energy conversion. However, metals screen electric fields and this has, so far, prevented their use in the design of all-metal nanoparticle circuitry. Here, we show that simple electronic circuits can be made exclusively from metal nanoparticles functionalized with charged organic ligands. In these materials, electronic currents are controlled by the ionic gradients of mobile counterions surrounding the 'jammed' nanoparticles. The nanoparticle-based electronic elements of the circuitry can be interfaced with metal nanoparticles capable of sensing various environmental changes (humidity, gas, the presence of various cations), creating electronic devices in which metal nanoparticles sense, process and ultimately report chemical signals. Because the constituent nanoparticles combine electronic and chemical sensing functions, we term these systems 'chemoelectronic'. The circuits have switching times comparable to those of polymer electronics, selectively transduce parts-per-trillion chemical changes into electrical signals, perform logic operations, consume little power (on the scale of microwatts), and are mechanically flexible. They are also 'green', in the sense that they comprise non-toxic nanoparticles cast at room temperature from alcohol solutions.

  4. Chemoelectronic circuits based on metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Yan, Yong; Warren, Scott C.; Fuller, Patrick; Grzybowski, Bartosz A.

    2016-07-01

    To develop electronic devices with novel functionalities and applications, various non-silicon-based materials are currently being explored. Nanoparticles have unique characteristics due to their small size, which can impart functions that are distinct from those of their bulk counterparts. The use of semiconductor nanoparticles has already led to improvements in the efficiency of solar cells, the processability of transistors and the sensitivity of photodetectors, and the optical and catalytic properties of metal nanoparticles have led to similar advances in plasmonics and energy conversion. However, metals screen electric fields and this has, so far, prevented their use in the design of all-metal nanoparticle circuitry. Here, we show that simple electronic circuits can be made exclusively from metal nanoparticles functionalized with charged organic ligands. In these materials, electronic currents are controlled by the ionic gradients of mobile counterions surrounding the ‘jammed’ nanoparticles. The nanoparticle-based electronic elements of the circuitry can be interfaced with metal nanoparticles capable of sensing various environmental changes (humidity, gas, the presence of various cations), creating electronic devices in which metal nanoparticles sense, process and ultimately report chemical signals. Because the constituent nanoparticles combine electronic and chemical sensing functions, we term these systems ‘chemoelectronic’. The circuits have switching times comparable to those of polymer electronics, selectively transduce parts-per-trillion chemical changes into electrical signals, perform logic operations, consume little power (on the scale of microwatts), and are mechanically flexible. They are also ‘green’, in the sense that they comprise non-toxic nanoparticles cast at room temperature from alcohol solutions.

  5. Antitumor Activities of Metal Oxide Nanoparticles

    PubMed Central

    Vinardell, Maria Pilar; Mitjans, Montserrat

    2015-01-01

    Nanoparticles have received much attention recently due to their use in cancer therapy. Studies have shown that different metal oxide nanoparticles induce cytotoxicity in cancer cells, but not in normal cells. In some cases, such anticancer activity has been demonstrated to hold for the nanoparticle alone or in combination with different therapies, such as photocatalytic therapy or some anticancer drugs. Zinc oxide nanoparticles have been shown to have this activity alone or when loaded with an anticancer drug, such as doxorubicin. Other nanoparticles that show cytotoxic effects on cancer cells include cobalt oxide, iron oxide and copper oxide. The antitumor mechanism could work through the generation of reactive oxygen species or apoptosis and necrosis, among other possibilities. Here, we review the most significant antitumor results obtained with different metal oxide nanoparticles.

  6. Antimicrobial activity of the metals and metal oxide nanoparticles.

    PubMed

    Dizaj, Solmaz Maleki; Lotfipour, Farzaneh; Barzegar-Jalali, Mohammad; Zarrintan, Mohammad Hossein; Adibkia, Khosro

    2014-11-01

    The ever increasing resistance of pathogens towards antibiotics has caused serious health problems in the recent years. It has been shown that by combining modern technologies such as nanotechnology and material science with intrinsic antimicrobial activity of the metals, novel applications for these substances could be identified. According to the reports, metal and metal oxide nanoparticles represent a group of materials which were investigated in respect to their antimicrobial effects. In the present review, we focused on the recent research works concerning antimicrobial activity of metal and metal oxide nanoparticles together with their mechanism of action. Reviewed literature indicated that the particle size was the essential parameter which determined the antimicrobial effectiveness of the metal nanoparticles. Combination therapy with the metal nanoparticles might be one of the possible strategies to overcome the current bacterial resistance to the antibacterial agents. However, further studies should be performed to minimize the toxicity of metal and metal oxide nanoparticles to apply as proper alternatives for antibiotics and disinfectants especially in biomedical applications.

  7. Bulk photoemission from metal films and nanoparticles

    SciTech Connect

    Ikhsanov, R Sh; Babicheva, V E; Protsenko, I E; Uskov, A V; Guzhva, M E

    2015-01-31

    Internal emission of photoelectrons from metal films and nanoparticles (nanowires and nanospheres) into a semiconductor matrix is studied theoretically by taking into account the jump of the effective electron mass at the metal – semiconductor interface and the cooling effect of hot electrons due to electron – electron collisions in the metal. The internal quantum efficiency of photoemission for the film and nanoparticles of two types (nanospheres and nanowires) is calculated. It is shown that the reduction of the effective mass of the electron during its transition from metal to semiconductor may lead to a significant (orders of magnitude and higher) decrease in the internal quantum efficiency of bulk photoemission. (nanostructures)

  8. Corrosion processes of physical vapor deposition-coated metallic implants.

    PubMed

    Antunes, Renato Altobelli; de Oliveira, Mara Cristina Lopes

    2009-01-01

    Protecting metallic implants from the harsh environment of physiological fluids is essential to guaranteeing successful long-term use in a patient's body. Chemical degradation may lead to the failure of an implant device in two different ways. First, metal ions may cause inflammatory reactions in the tissues surrounding the implant and, in extreme cases, these reactions may inflict acute pain on the patient and lead to loosening of the device. Therefore, increasing wear strength is beneficial to the performance of the metallic implant. Second, localized corrosion processes contribute to the nucleation of fatigue cracks, and corrosion fatigue is the main reason for the mechanical failure of metallic implants. Common biomedical alloys such as stainless steel, cobalt-chrome alloys, and titanium alloys are prone to at least one of these problems. Vapor-deposited hard coatings act directly to improve corrosion, wear, and fatigue resistances of metallic materials. The effectiveness of the corrosion protection is strongly related to the structure of the physical vapor deposition layer. The aim of this paper is to present a comprehensive review of the correlation between the structure of physical vapor deposition layers and the corrosion properties of metallic implants.

  9. Biodegradable metallic materials for orthopaedic implantations: A review.

    PubMed

    Yeung, Kelvin W K; Wong, Karen H M

    2012-09-06

    Non-degradable metals such as stainless steel, cobalt-chromium-based alloys, titanium and its alloys may lead to stress shielding effect after fractured bone has healed. This complication may attribute to the non-degradability and the mismatch of the mechanical properties between these metallic implants and human bone. Biodegradable metallic materials have been therefore studied as alternative implantable metals in orthopaedics for some years. Magnesium is a potential candidate, as its mechanical properties are similar to human. Additionally, it is degradable and its ions are essential for cell functions. However, rapid degradation and release of hydrogen gas may inhibit its applications clinically. Hence, this paper reviews the development of the biodegradable metallic implants and various methods to improve the degradation of magnesium alloys.

  10. Stabilizing metal nanoparticles for heterogeneous catalysis.

    PubMed

    Cao, Anmin; Lu, Rongwen; Veser, Götz

    2010-11-07

    Metal nanoparticles hold great promise for heterogeneous catalysis due to their high dispersion, large concentration of highly undercoordinated surface sites, and the presence of quantum confinement effects, which can drastically alter their reactivity. However, the poor thermal stability of nano-sized particles limits their use to low temperature conditions and constitutes one of the key hurdles towards industrial application. The present perspective paper briefly reviews the mechanisms underlying nanoparticle sintering, and then gives an overview of emerging approaches towards stabilizing metal nanoparticles for heterogeneous catalysis. We conclude by highlighting the current needs for further developments in the field.

  11. Photopolymerization of conductive polymeric metal nanoparticles.

    PubMed

    Cai, Xichen; Anyaogu, Kelechi C; Neckers, Douglas C

    2009-11-01

    5-Mercapto-2,2'-bithiophene functionalized metal nanoparticles BTSMs [M: copper (Cu), silver (Ag), and gold (Au)] of different diameters (2-8 nm) were synthesized. Conductive polymeric metal nanoparticles were formed from BTSM by UV irradiation. The photopolymerization mechanism was investigated using transient absorption measurements. Intramolecular electron transfer from the ligand to the metal nano-core was confirmed. Nanoparticle size, as well as plasmon electronic interactions, are important factors. The smaller the nanoparticle and the stronger the electronic interactions, the faster the electron transfer is. The three-dimensional structure of the polymerized BTSM was identified using transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The conductivity of polymerized BTSM measured in poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT/PSS) film is higher than that of the nonpolymerized BTSM.

  12. Laser trapping of colloidal metal nanoparticles.

    PubMed

    Lehmuskero, Anni; Johansson, Peter; Rubinsztein-Dunlop, Halina; Tong, Lianming; Käll, Mikael

    2015-01-01

    Optical trapping using focused laser beams (laser tweezers) has been proven to be extremely useful for contactless manipulation of a variety of small objects, including biological cells, organelles within cells, and a wide range of other dielectric micro- and nano-objects. Colloidal metal nanoparticles have drawn increasing attention in the field of optical trapping because of their unique interactions with electromagnetic radiation, caused by surface plasmon resonance effects, enabling a large number of nano-optical applications of high current interest. Here we try to give a comprehensive overview of the field of laser trapping and manipulation of metal nanoparticles based on results reported in the recent literature. We also discuss and describe the fundamentals of optical forces in the context of plasmonic nanoparticles, including effects of polarization, optical angular momentum, and laser heating effects, as well as the various techniques that have been used to trap and manipulate metal nanoparticles. We conclude by suggesting possible directions for future research.

  13. Biomolecule-coated metal nanoparticles on titanium.

    PubMed

    Christensen, Stephen L; Chatt, Amares; Zhang, Peng

    2012-02-07

    Immobilizations of nanoparticles and biomolecules on biocompatible substrates such as titanium are two promising approaches to bringing new functionalities to Ti-based biomaterials. Herein, we used a variety of X-ray spectroscopic techniques to study and better understand metal-thiolate interactions in biofunctionalized metal nanoparticle systems supported on Ti substrates. Using a facile one-step procedure, a series of Au nanoparticle samples with varied biomolecule coatings ((2-mercatopropionyl)glycine (MPG) and bovine serum albumin (BSA)) and biomolecule concentrations are prepared. Ag and Pd systems are also studied to observe change with varying metal composition. The structure and properties of these biomolecule-coated nanoparticles are investigated with scanning electron microscopy (SEM) and element-specific X-ray techniques, including extended X-ray absorption fine structure (Au L(3)-edge), X-ray absorption near-edge structure (Au L(3), Ag L(3), Pd L(3), and S K-edge), and X-ray photoelectron spectroscopy (Au 4f, Ag 3d, Pd 3d, and S 2p core level). It was found that, by comparison of SEM and X-ray spectroscopy results, the coating of metal nanoparticles with varying model biomolecule systems can have a significant effect on both surface coverage and organization. This work offers a facile chemical method for bio- and nanofunctionalization of Ti substrates as well as provides a physical picture of the structure and bonding of biocoated metal nanoparticles, which may lead to useful applications in orthopedics and biomedicine.

  14. Availability of Total Knee Arthroplasty Implants for Metal Hypersensitivity Patients

    PubMed Central

    Ajwani, Sanil Harji; Charalambous, Charalambos P.

    2016-01-01

    Purpose To provide information on the type of “hypersensitivity-friendly” components available for primary total knee arthroplasty (TKA) in the current market. Materials and Methods Implant manufactures were identified using the 2013 National Joint Registries of the United Kingdom and Sweden and contacted to obtain information about the products they offer for patients with metal hypersensitivity. Results Information on 23 TKA systems was provided by 13 implant manufacturers. Of these, 15 systems had options suitable for metal hypersensitivity patients. Two types of “hypersensitivity-friendly” components were identified: 10 implants were cobalt chrome prostheses with a “hypersensitivity-friendly” outer coating and 5 implants were made entirely from non-cobalt chrome alloys. Conclusions The results of this study suggest that several hypersensitivity TKA options exist, some of which provide the same designs and surgical techniques as the conventional implants. The information in this study can guide TKA surgeons in making informed choices about implants and identifying implants that could be examined in future controlled studies comparing outcomes between “hypersensitivity-friendly” and conventional implants. PMID:27894179

  15. Metal-insulator-metal capacitor using electrosprayed nanoparticles

    NASA Astrophysics Data System (ADS)

    Véliz, Bremnen; Bermejo, Sandra; Coll, Arnau; Castañer, Luis

    2014-07-01

    An electrospray technique has been used to deposit SiO2 nanoparticles as insulator layer of a metal-insulator-metal device. Impedance spectroscopy measurements show that a 4.4 factor increase in capacitance is achieved compared to a continuous dielectric layer of the same permittivity and dimensions.

  16. Implantation of nitrogen, carbon, and phosphorus ions into metals

    SciTech Connect

    Guseva, M.I.; Gordeeva, G.V.

    1987-01-01

    The application of ion implantation for alloying offers a unique opportunity to modify the chemical composition, phase constitution, and microstructure of the surface layers of metals. The authors studied ion implantation of nitrogen and carbon into the surface layers of metallic targets. The phase composition of the implanted layers obtained on the Kh18N10T stainless steel, the refractory molybdenum alloy TsM-6, niobium, and nickel was determined according to the conventional method of recording the x-ray diffraction pattern of the specimens using monochromatic FeK/sub alpha/-radiation on a DRON-2,0 diffractometer. The targets were bombarded at room temperature in an ILU-3 ion accelerator. The implantation of metalloid ions was also conducted with the targets being bombarded with 100-keV phosphorus ions and 40-keV carbon ions.

  17. Advanced Organic Ligands for Protecting Metal Nanoparticles

    NASA Astrophysics Data System (ADS)

    Yu, Jonathan Ka-Wing

    Organic monolayer protected metal nanoparticles have been utilized in many different fields such as catalysis, drug delivery, and sensor chemistry. However, these nanomaterials are prone to increase in size consequently losing its function at the nanoscale. The stability these nanoparticles have been a great interest of research. This thesis focuses on the synthesis of a novel cross-linkable ligand for the protection of metal nanoparticles. Chapter 1 reviews key concepts of nanoparticles, its usefulness in applications, some of the stabilizing strategies employed, and the scope of the thesis project. Chapter 2 describes the synthetic attempts and optimization of the novel cross-linkable ligand. In addition, its characterization data is also included. Section 2.8 also highlights another fully synthesized novel hydrophobic ligand. Chapter 3 contains the summary of the work and closing remarks. Future works is also included to describe the prospects of the synthesis of the novel ligand. Chapter 4 entails the experimental data and supplementary information.

  18. Noble Metal Nanoparticles for Biosensing Applications

    PubMed Central

    Doria, Gonçalo; Conde, João; Veigas, Bruno; Giestas, Leticia; Almeida, Carina; Assunção, Maria; Rosa, João; Baptista, Pedro V.

    2012-01-01

    In the last decade the use of nanomaterials has been having a great impact in biosensing. In particular, the unique properties of noble metal nanoparticles have allowed for the development of new biosensing platforms with enhanced capabilities in the specific detection of bioanalytes. Noble metal nanoparticles show unique physicochemical properties (such as ease of functionalization via simple chemistry and high surface-to-volume ratios) that allied with their unique spectral and optical properties have prompted the development of a plethora of biosensing platforms. Additionally, they also provide an additional or enhanced layer of application for commonly used techniques, such as fluorescence, infrared and Raman spectroscopy. Herein we review the use of noble metal nanoparticles for biosensing strategies—from synthesis and functionalization to integration in molecular diagnostics platforms, with special focus on those that have made their way into the diagnostics laboratory. PMID:22438731

  19. Metallic and semiconducting nanoparticles in LCs

    NASA Astrophysics Data System (ADS)

    Sharma, Anshul; Urbanski, Martin; Mori, Taizo; Kitzerow, Heinz-S.; Hegmann, Torsten

    This chapter provides an overview of recent advances in nanoparticleliquid crystal dispersions with a particular focus on bulk versus surface effects. Surface effects will include the role of surface functionalization of metal and semiconducting nanoparticles as well as interfacial effects, alignment and anchoring in thin liquid crystal films related to nanoparticle segregation. We will also try to provide a practical guide for experimental work on nanoparticle-liquid crystal dispersions, including tips and best practices for preparing dispersions, detecting and preventing inhomogeneities as well as Dos and Don'ts for handling samples and filling test cells for electrooptic, spectroscopic, and other experiments critical for research in this area.

  20. Structure and Energy Stability of Metal Nanoparticles

    NASA Astrophysics Data System (ADS)

    Barron, Hector; Palomares-Baez, Juan Pedro; Velazquez-Salazar, Jesus; Rodriguez-Lopez, Jose Luis; Jose-Yacaman, Miguel; University of Texas at San Antonio Collaboration; Instituto Potosino de Investigacion Cientufica y Tecnologica Collaboration

    2011-03-01

    In this work we present a theoretical model for the structural evolution and energy stability for metal nanoparticles from the small (1-2 nm) to the big (~ 50 nm) size ranges. We have found that the appearances of structural lattice defects as well as surface reconstructions are important factors that highly influence the growth process. A simple assembly model for a path transformation for metal nanoparticles is presented and compare with experimental evidence. Acknowledgements: Financial support from National Science Foundation Grant DMR-0934218 is acknowledged, as well as grants for the use of High Performance Computational Resources from the supercomputer center TACC-University of Texas at Austin.

  1. Electroluminescence Efficiency Enhancement using Metal Nanoparticles

    DTIC Science & Technology

    2008-06-22

    the vicinity of isolated metal nanoparticles and their arrays. Using the example of an InGaN /GaN quantum-well active region positioned in close...emitters placed in the vicinity of isolated metal nanoparticles and their arrays. Using the example of an InGaN /GaN quantum-well active region...electron-hole pair states are localized on the scale of the coherent length on the order of a few nanometers at room temperature, the spontaneous

  2. Ion Implantation Effects on the Metal-Semiconductor Interfaces.

    NASA Astrophysics Data System (ADS)

    Yapsir, Andrie Setiawan

    1988-12-01

    In this thesis, the effects of ion implantation on metal-semiconductor interfaces are studied. Hydrogen ions have been used as the implanted species. The implantation is carried out on Al/n-Si Schottky contacts. Electrical characterizations, deep level transient spectroscopy measurements, and the ^{15}N hydrogen profiling technique have been used to study the effects of ion implantation. It is demonstrated that the defect centers in the depletion region created by hydrogen implantation have more likely negative or possibly neutral signatures, rather than a positive signature as has been previously speculated. These negatively charged centers compensate for the positive donor resulting in a widening of the depletion region and reduction in the capacitance of the metal-semiconductor contacts. The tendency of hydrogen to passivate its own damage which results in the recovery of electronic transport across the metal-semiconductor junction upon low temperature heat treatment is also demonstrated. In connection with the behavior of hydrogen in silicon, in the second part of this thesis, detailed theoretical calculations on the hydrogen passivation of defects in silicon are carried out. A particular type of defect, namely, a substitutional sulfur in silicon, is chosen and is studied using the modified intermediate neglect of differential overlap (MINDO/3) molecular orbital method. It is found that the sulfur center can be passivated using one or two hydrogen atoms. The calculations indicate that the most stable positions of the hydrogen atoms are between the sulfur and its silicon neighbors. The hydrogens bond to the nearest silicon atoms and only weakly interact with the sulfur. Thermochemistry considerations predict that a single hydrogen passivates the sulfur center, provided these centers are in abundance in the silicon. Hydrogen ion implantation has also been carried out on Schottky contacts having a large difference in metal work function, Ti/p-Si and Pt

  3. Laser-Induced Transfer of Metal Nanoparticles

    NASA Astrophysics Data System (ADS)

    Kuznetsov, Arseniy I.; Koch, Jürgen; Chichkov, Boris N.

    2010-10-01

    A novel approach for the fabrication of metallic micro- and nanostructures based on femtosecond laser-induced transfer of metallic nanodroplets is developed. The size of the transferred droplets depends on the volume of laser-molten metal and can be varied by changing the laser beam focus on the sample surface and the metal film thickness. Controllable fabrication of high quality spherical gold micro- and nanoparticles with sizes between 170 nm and 1500 nm is realized. Fabrication of miscellaneous structures consisting of gold particles as elementary building blocks is demonstrated.

  4. Alloy metal nanoparticles for multicolor cancer diagnostics

    NASA Astrophysics Data System (ADS)

    Baptista, Pedro V.; Doria, Gonçalo; Conde, João

    2011-03-01

    Cancer is a multigenic complex disease where multiple gene loci contribute to the phenotype. The ability to simultaneously monitor differential expression originating from each locus results in a more accurate indicator of degree of cancerous activity than either locus alone. Metal nanoparticles have been thoroughly used as labels for in vitro identification and quantification of target sequences. We have synthesized nanoparticles with assorted noble metal compositions in an alloy format and functionalized them with thiol-modified ssDNA (nanoprobes). These nanoprobes were then used for the simultaneous specific identification of several mRNA targets involved in cancer development - one pot multicolor detection of cancer expression. The different metal composition in the alloy yield different "colors" that can be used as tags for identification of a given target. Following a non-cross-linking hybridization procedure previously developed in our group for gold nanoprobes, these multicolor nanoprobes were used for the molecular recognition of several different targets including differently spliced variants of relevant genes (e.g. gene products involved in chronic myeloid leukemia BCR, ABL, BCR-ABL fusion product). Based on the spectral signature of mixtures, before and after induced aggregation of metal nanoparticles, the correct identification could be made. Further application to differentially quantify expression of each locus in relation to another will be presented. The differences in nanoparticle stability and labeling efficiency for each metal combination composing the colloids, as well as detection capability for each nanoprobe will be discussed. Additional studies will be conducted towards allele specific expression studies.

  5. [Should metal alloy discs be used for patch testing in suspected metal implant intolerance reaction?].

    PubMed

    Thomas, P; Geier, J; Dickel, H; Diepgen, T; Hillen, U; Kreft, B; Schnuch, A; Szliska, C; Mahler, V

    2015-11-01

    Intolerance reactions to metal implants may be caused by metal allergy. However, prior to implantation, patch testing should not be done in a prophylactic-prophetic approach. Pre-implant patch testing should only be performed to verify or exclude metal allergy in patients with a reported respective history. In the case of implant-in particular arthroplasty-related complications like, for example, pain, effusion, skin changes, reduced range of motion, or loosening, orthopedic-surgical differential diagnostics should be performed first. Allergological workup of suspected metal implant allergy should be done with the DKG baseline series which contains nickel-, cobalt- and chromium-preparations. Various studies assessing the usefulness of metal alloy discs for patch testing proved that this approach does not give reliable information about metal allergy. Positive patch test reactions to the discs cannot be assigned to a specific metal within the disc alloy components. Furthermore, availability of such metal discs might be an invitation to uncritical testing. Accordingly, due to lack of benefit in comparison to patch testing with standardized metal salt preparations, we do not recommend patch testing with metal alloy discs.

  6. Metal and metal oxide nanoparticle synthesis from metal organic frameworks (MOFs): finding the border of metal and metal oxides.

    PubMed

    Das, Raja; Pachfule, Pradip; Banerjee, Rahul; Poddar, Pankaj

    2012-01-21

    Herein, for the first time, we report a generalized strategy for the successful synthesis of highly crystalline metal and metal oxide nanoparticles embedded in a carbon matrix by the controlled thermolysis of metal organic frameworks (MOFs). The rationalized synthesis strategy of a broad range of metal and metal oxides nanoparticles, such as Cu/CuO, Co/Co(3)O(4), ZnO, Mn(2)O(3), MgO and CdS/CdO, by thermolysis of MOFs demonstrates for the first time that metal ions with a reduction potential of -0.27 volts or higher present in MOFs always form pure metal nanoparticles during thermolysis in N(2), whereas metal ions with a reduction potential lower than -0.27 volts form metal oxide nanoparticles during thermolysis in N(2). Another point of interest is the fact that we have found a unique relationship between the nanoparticle size and the distance between the secondary building units inside the MOF precursors. Interestingly, the crystallinity of the carbon matrix was also found to be greatly influenced by the environment (N(2) and air) during thermolysis. Moreover, these nanoparticles dispersed in a carbon matrix showed promising H(2) and CO(2) adsorption properties depending on the environment used for the thermolysis of MOFs.

  7. [Biodeterioration and corrosion of metallic implants and prostheses].

    PubMed

    López, G D

    1993-01-01

    The use of surgical implants and prosthetic devices to replace the original function of different components of the human biological system is a well established tradition in the history of medicine. Currently, one of the most prevalent points of view in dealing with this subject, is that of biocompatibility of materials of construction and methods of fabrication of these devices, in order to avoid negative impacts on the patient due to failure of implants through degradation mechanisms such as corrosion. This article presents a current general review of the relationship between biocompatibility and deterioration of metallic implants and prosthetic devices, emphasizing the specific forms that corrosion adopts in biological media. The historical perspective shows the consolidation of a tendency towards a more systematic study of these phenomena in recent years, as opposed to trial and error practices that used to be common before the third decade of this century. The understanding of interactions between implants and biological tissue, thus led to some of the most promising current techniques, such as the use of powder metallurgy components to optimize skeletal fixation of implants by means of interstitial bone growth into porous metallic surfaces. The review of metals and alloys currently used for the fabrication of implants shows the amplitude of available technological alternatives, as well as the multiple criteria required to make a good selection for each specific case. Applications and pros and cons of stainless steel, Cr, Ni, Co and Ti alloys, and tantalum are briefly discussed. The introduction to basic concepts of corrosion, serves as a basis for the description of the typical forms that these phenomena adopt in biological media, including pitting, crevice corrosion, fatigue-corrosion, stress corrosion, fretting corrosion, galvanic corrosion, and intergranular corrosion. This review shows that the study of interactions between biological media and metallic

  8. Plasma immersion ion implantation for reducing metal ion release

    SciTech Connect

    Diaz, C.; Garcia, J. A.; Maendl, S.; Pereiro, R.; Fernandez, B.; Rodriguez, R. J.

    2012-11-06

    Plasma immersion ion implantation of Nitrogen and Oxygen on CoCrMo alloys was carried out to improve the tribological and corrosion behaviors of these biomedical alloys. In order to optimize the implantation results we were carried experiments at different temperatures. Tribocorrosion tests in bovine serum were used to measure Co, Cr and Mo releasing by using Inductively Coupled Plasma Mass Spectrometry analysis after tests. Also, X-ray Diffraction analysis were employed in order to explain any obtained difference in wear rate and corrosion tests. Wear tests reveals important decreases in rate of more than one order of magnitude for the best treatment. Moreover decreases in metal release were found for all the implanted samples, preserving the same corrosion resistance of the unimplanted samples. Finally this paper gathers an analysis, in terms of implantation parameters and achieved properties for industrial implementation of these treatments.

  9. Plasma immersion ion implantation for reducing metal ion release

    NASA Astrophysics Data System (ADS)

    Díaz, C.; García, J. A.; Mändl, S.; Pereiro, R.; Fernández, B.; Rodríguez, R. J.

    2012-11-01

    Plasma immersion ion implantation of Nitrogen and Oxygen on CoCrMo alloys was carried out to improve the tribological and corrosion behaviors of these biomedical alloys. In order to optimize the implantation results we were carried experiments at different temperatures. Tribocorrosion tests in bovine serum were used to measure Co, Cr and Mo releasing by using Inductively Coupled Plasma Mass Spectrometry analysis after tests. Also, X-ray Diffraction analysis were employed in order to explain any obtained difference in wear rate and corrosion tests. Wear tests reveals important decreases in rate of more than one order of magnitude for the best treatment. Moreover decreases in metal release were found for all the implanted samples, preserving the same corrosion resistance of the unimplanted samples. Finally this paper gathers an analysis, in terms of implantation parameters and achieved properties for industrial implementation of these treatments.

  10. 77 FR 5813 - Cardiovascular Metallic Implants: Corrosion, Surface Characterization, and Nickel Leaching...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-06

    ... HUMAN SERVICES Food and Drug Administration Cardiovascular Metallic Implants: Corrosion, Surface... public workshop entitled ``Cardiovascular Metallic Implants: Corrosion, Surface Characterization, and... device manufacturers, test houses, and academia to discuss corrosion, surface characterization,...

  11. The effect of metal detector gates on implanted permanent pacemakers.

    PubMed

    Copperman, Y; Zarfati, D; Laniado, S

    1988-10-01

    The effect of metal detector security gates, such as are used in airports, was tested in 103 nonselected pacemaker patients. Various types of single and dual chamber units were examined, using telemetry during the test. Pulse rate and duration were measured immediately before and after the procedure. No ill effect was seen on any of the units tested, pacemaker inhibition was not observed, and programmability was not affected. Metal detector security gates have no effect on implanted permanent pacemakers.

  12. Synthesis of Graphite Encapsulated Metal Nanoparticles and Metal Catalyzed Nanotubes

    NASA Technical Reports Server (NTRS)

    vanderWal, R. L.; Dravid, V. P.

    1999-01-01

    This work focuses on the growth and inception of graphite encapsulated metal nanoparticles and metal catalyzed nanotubes using combustion chemistry. Deciphering the inception and growth mechanism(s) for these unique nanostructures is essential for purposeful synthesis. Detailed knowledge of these mechanism(s) may yield insights into alternative synthesis pathways or provide data on unfavorable conditions. Production of these materials is highly desirable given many promising technological applications.

  13. Terahertz pulse generation from metal nanoparticle ink

    NASA Astrophysics Data System (ADS)

    Kato, Kosaku; Takano, Keisuke; Tadokoro, Yuzuru; Phan, Thanh Nhat Khoa; Nakajima, Makoto

    2016-11-01

    Terahertz pulse generation from metallic nanostructures irradiated by femtosecond laser pulses is of interest because the conversion efficiency from laser pulses to terahertz waves is increased by the local field enhancement resulting from the plasmon oscillation. In this talk we present our recent study on terahertz generation from metal nanoparticle ink. We baked a silver nanoparticle ink spin-coated onto a glass coverslip in various temperatures. On the surface of the baked ink, bumpy nanostructures are spontaneously formed, and the average size of bumps depends on the baking temperature. These structures are expected to lead to local field enhancement and then large nonlinear polarizations on the surface. The baked ink was irradiated by the output of regeneratively amplified Ti:sapphire femtosecond laser at an incidence angle of 45°. Waveforms of generated terahertz pulses are detected by electro-optical sampling. The generation efficiency was high when the average diameter of bumps was around 100 nm, which is realized when the ink is baked in 205 to 235°C in our setup. One of our next research targets is terahertz wave generation from micro-patterned metallic nanoparticle ink. It is an advantage of the metal nanoparticle ink that by using inkjet printers one can fabricate various patterns with micrometer scales, in which terahertz waves have a resonance. Combination of microstructures made by a printer and nanostructure spontaneously formed in the baking process will provide us terahertz emitters with unique frequency characteristics.

  14. Ion Implantation Studies of Titanium Metal Surfaces.

    DTIC Science & Technology

    1981-01-01

    Lorenzelli and R. Pascard, Compt. Rend. 259, (1964) 2442-2444. 8. Linus Pauling , The Nature of the Chemical Bond, pg. 92 (Cornell Univ. Press, Ithaca...K. Hirvonen. 3. S. Spooner and K. 0. Legg,lon Implantation Metallurgy, 162 (1980); ed. C. M. Preece and J. K. Hirvonen. 4. L. Pauling , The Nature of...R from the Pauling electronegativity scale. According to Pauling (8), the contribu- tion of the bond to the heat of formation is Q - 23 (YEr - Yc) 2

  15. Metal nanoparticles in DBS card materials modification

    NASA Astrophysics Data System (ADS)

    Metelkin, A.; Frolov, G.; Kuznetsov, D.; Kolesnikov, E.; Chuprunov, K.; Kondakov, S.; Osipov, A.; Samsonova, J.

    2015-11-01

    In the recent years the method of collecting and storing Dried Blood Spots (DBS) on special cellulose membrane (paper) has gained wide popularity. But possible damage of biosamples caused by microorganisms in case of their incomplete drying is a disadvantage of the method. It can be overcome by treating sample-collection membranes with colloidal solutions of metal nanoparticles, having antibacterial effect. The team studied antibacterial properties of nonwoven material samples with various coatings (alcohol sols of copper, aluminium, iron, titanium, silver and vanadium nanoparticles). Colloidal solutions of nanoparticles were obtained by means of electroerosion method with further low-temperature plasma condensation. Antibacterial activity of fiberglass and cellulose membrane samples with nanoparticle coatings was studied using B. cereus and plaque bacteria cultures. It was revealed that nanostructured coatings can suppress bacterial activity; in addition they can diffuse from the membrane surface into medium which leads to widening the areas of inhibiting testing cultures’ growth. Thus, membrane materials treatment with alcohol-sols of metal nanoparticles can be seen as promising for conferring antibacterial properties to DBS carriers.

  16. Stimuli responsive release of metalic nanoparticles on semiconductor substrates.

    PubMed

    Santiago-Cordoba, Miguel; Topal, Özge; Allara, David L; Kalkan, A Kaan; Demirel, Melik C

    2012-04-10

    Optically active metal nanoparticles have been of recent and broad interest for applications to biomarker detection because of their ability to enable high sensitivity enhancements in various optical detection techniques. Here, we report stimuli responsive release of metallic nanoparticles on a semiconductor thin film array structure based on pH change. The metallic nanoparticles are obtained by a simple redox procedure on the semiconductor surface. This approach allows controlling nanoparticle surface coatings in situ for biomolecule conjugation, such as DNA probes on nanoparticles, and rapid stimuli responsive release of these nanoparticles upon pH change.

  17. Nanoscale size dependence on pulsed laser sintering of hydroxyapatite/titanium particles on metal implants

    NASA Astrophysics Data System (ADS)

    Zhang, Martin Yi; Cheng, Gary J.

    2010-12-01

    Nanoscale size effects on pulsed laser coating of hydroxyapatite/titanium nanoparticles (nanoTi) on metal substrate is discussed in this article. Laser coating method has recently been developed to coat bioceramics material on Ti-6Al-4V substrate. Laser-coated bioceramics implants have several advantages due to the use of nanosized materials: strong interfacial bonding strength, good biocompatibility and potentially longer lifetime cycle. These advantages benefit from intrinsic properties of nanoparticles. Size effects on melting point, heat capacity, thermal, and electrical conductivities have been discussed. Multiphysics model is built to reveal the mechanism of laser coating process. Two submodules are included in the model: electromagnetic module to represent the laser-nanoparticle interactions and heat transfer module to simulate the heat conduction. Both simulation and experimental results showed that nanoTi, functioning as nanoheaters, effectively enhances the laser coating sinterability. For large nanoTi (>100 nm), sinterability enhancement mainly attributes to the stronger laser-particle interactions due to higher plasmon resonance; for small nanoparticles (<100 nm), not only stronger laser-nanoparticle interactions, reduction on melting point also contributes to sinterability enhancement.

  18. Metal-doped semiconductor nanoparticles and methods of synthesis thereof

    DOEpatents

    Ren, Zhifeng; Chen, Gang; Poudel, Bed; Kumar, Shankar; Wang, Wenzhong; Dresselhaus, Mildred

    2009-09-08

    The present invention generally relates to binary or higher order semiconductor nanoparticles doped with a metallic element, and thermoelectric compositions incorporating such nanoparticles. In one aspect, the present invention provides a thermoelectric composition comprising a plurality of nanoparticles each of which includes an alloy matrix formed of a Group IV element and Group VI element and a metallic dopant distributed within the matrix.

  19. Metal-doped semiconductor nanoparticles and methods of synthesis thereof

    NASA Technical Reports Server (NTRS)

    Ren, Zhifeng (Inventor); Chen, Gang (Inventor); Poudel, Bed (Inventor); Kumar, Shankar (Inventor); Wang, Wenzhong (Inventor); Dresselhaus, Mildred (Inventor)

    2009-01-01

    The present invention generally relates to binary or higher order semiconductor nanoparticles doped with a metallic element, and thermoelectric compositions incorporating such nanoparticles. In one aspect, the present invention provides a thermoelectric composition comprising a plurality of nanoparticles each of which includes an alloy matrix formed of a Group IV element and Group VI element and a metallic dopant distributed within the matrix.

  20. Carbon-supported base metal nanoparticles: cellulose at work.

    PubMed

    Hoekstra, Jacco; Versluijs-Helder, Marjan; Vlietstra, Edward J; Geus, John W; Jenneskens, Leonardus W

    2015-03-01

    Pyrolysis of base metal salt loaded microcrystalline cellulose spheres gives a facile access to carbon-supported base metal nanoparticles, which have been characterized with temperature-dependent XRD, SEM, TEM, ICP-MS and elemental analysis. The role of cellulose is multifaceted: 1) it facilitates a homogeneous impregnation of the aqueous base metal salt solutions, 2) it acts as an efficacious (carbonaceous) support material for the uniformly dispersed base metal salts, their oxides and the metal nanoparticles derived therefrom, and 3) it contributes as a reducing agent via carbothermal reduction for the conversion of the metal oxide nanoparticles into the metal nanoparticles. Finally, the base metal nanoparticles capable of forming metastable metal carbides catalytically convert the carbonaceous support into a mesoporous graphitic carbon material.

  1. Effects of Ti charge state, ion size and beam-induced compaction on the formation of Ag metal nanoparticles in fused silica

    NASA Astrophysics Data System (ADS)

    Magruder, R. H.; Meldrum, A.; Haglund, R. F.

    2015-04-01

    Metal nanoparticles formed by ion implantation in fused silica exhibit linear and nonlinear optical properties that can be altered by co-doping the silica substrate with transition-metal ions. For example, implantation of scandium in fused silica creates a directional optical dichroism due to the different spatial distribution of silver nanoparticles subsequently formed by Ag ion implantation. In this paper, we show that implantation of titanium ions alters the short- and intermediate-range order in the silica and thereby alters the diffusion and nucleation processes that lead to formation of silver nanoparticles. In particular, the dichroic response observed for Ag nanoparticles in Sc-implanted silica is, with one exception, in Ti-implanted silica. Compaction of the silica due to the ion implantation process appears to be similar for both Sc and Ti implantations, based on the observed shift of the 1,124 cm-1 transverse-optical phonon mode in the infrared reflectance spectrum. However, differences in chemical reactivity, bond lengths and electronic structure of Sc and Ti produce changes in electronic structure and strain that are sensitively reflected in the reflectance spectra of the Ag nanoparticles. These differences lead to modifications in the size, shape and spatial distributions of the silver nanoparticles and offer a powerful means of controlling their optical properties.

  2. Biosurfactant Mediated Biosynthesis of Selected Metallic Nanoparticles

    PubMed Central

    Płaza, Grażyna A.; Chojniak, Joanna; Banat, Ibrahim M.

    2014-01-01

    Developing a reliable experimental protocol for the synthesis of nanomaterials is one of the challenging topics in current nanotechnology particularly in the context of the recent drive to promote green technologies in their synthesis. The increasing need to develop clean, nontoxic and environmentally safe production processes for nanoparticles to reduce environmental impact, minimize waste and increase energy efficiency has become essential in this field. Consequently, recent studies on the use of microorganisms in the synthesis of selected nanoparticles are gaining increased interest as they represent an exciting area of research with considerable development potential. Microorganisms are known to be capable of synthesizing inorganic molecules that are deposited either intra- or extracellularly. This review presents a brief overview of current research on the use of biosurfactants in the biosynthesis of selected metallic nanoparticles and their potential importance. PMID:25110864

  3. Noble Metal Nanoparticles Applications in Cancer

    PubMed Central

    Conde, João; Doria, Gonçalo; Baptista, Pedro

    2012-01-01

    Nanotechnology has prompted new and improved materials for biomedical applications with particular emphasis in therapy and diagnostics. Special interest has been directed at providing enhanced molecular therapeutics for cancer, where conventional approaches do not effectively differentiate between cancerous and normal cells; that is, they lack specificity. This normally causes systemic toxicity and severe and adverse side effects with concomitant loss of quality of life. Because of their small size, nanoparticles can readily interact with biomolecules both at surface and inside cells, yielding better signals and target specificity for diagnostics and therapeutics. This way, a variety of nanoparticles with the possibility of diversified modification with biomolecules have been investigated for biomedical applications including their use in highly sensitive imaging assays, thermal ablation, and radiotherapy enhancement as well as drug and gene delivery and silencing. Here, we review the available noble metal nanoparticles for cancer therapy, with particular focus on those already being translated into clinical settings. PMID:22007307

  4. Coating of metal implant materials with strontium.

    PubMed

    Frank, Matthias J; Walter, Martin S; Tiainen, Hanna; Rubert, Marina; Monjo, Marta; Lyngstadaas, S Petter; Haugen, Håvard J

    2013-11-01

    The aim of this study was to show that cathodic polarization can be used for coating commercial implant surfaces with an immobilized but functional and bioavailable surface layer of strontium (Sr). Moreover, this study assessed the effect of fluorine on Sr-attachment. X-ray photoelectron spectroscopy revealed that addition of fluorine (F) to the buffer during coating increased surface Sr-amounts but also changed the chemical surface composition by adding SrF2 alongside of SrO whereas pre-treatment of the surface by pickling in hydrofluoric acid appeared to hinder Sr-attachment. Assessment of the bio-availability hinted at a positive effect of Sr on cell differentiation given that the surface reactivity of the original surface remained unchanged. Additional SrF2 on the surface appeared to reduce undesired surface contamination while maintaining the surface micro-topography and micro-morphology. Anyhow, this surface modification revealed to create nano-nodules on the surface.

  5. Microbial-mediated method for metal oxide nanoparticle formation

    DOEpatents

    Rondinone, Adam J.; Moon, Ji Won; Love, Lonnie J.; Yeary, Lucas W.; Phelps, Tommy J.

    2015-09-08

    The invention is directed to a method for producing metal oxide nanoparticles, the method comprising: (i) subjecting a combination of reaction components to conditions conducive to microbial-mediated formation of metal oxide nanoparticles, wherein said combination of reaction components comprise: metal-reducing microbes, a culture medium suitable for sustaining said metal-reducing microbes, an effective concentration of one or more surfactants, a reducible metal oxide component containing one or more reducible metal species, and one or more electron donors that provide donatable electrons to said metal-reducing microbes during consumption of the electron donor by said metal-reducing microbes; and (ii) isolating said metal oxide nanoparticles, which contain a reduced form of said reducible metal oxide component. The invention is also directed to metal oxide nanoparticle compositions produced by the inventive method.

  6. Interaction of mobile phones with superficial passive metallic implants.

    PubMed

    Virtanen, H; Huttunen, J; Toropainen, A; Lappalainen, R

    2005-06-07

    The dosimetry of exposure to radiofrequency (RF) electromagnetic (EM) fields of mobile phones is generally based on the specific absorption rate (SAR, W kg(-1)), which is the electromagnetic energy absorbed in the tissues per unit mass and time. In this study, numerical methods and modelling were used to estimate the effect of a passive, metallic (conducting) superficial implant on a mobile phone EM field and especially its absorption in tissues in the near field. Two basic implant models were studied: metallic pins and rings in the surface layers of the human body near the mobile phone. The aim was to find out 'the worst case scenario' with respect to energy absorption by varying different parameters such as implant location, orientation, size and adjacent tissues. Modelling and electromagnetic field calculations were carried out using commercial SEMCAD software based on the FDTD (finite difference time domain) method. The mobile phone was a 900 MHz or 1800 MHz generic phone with a quarter wave monopole antenna. A cylindrical tissue phantom models different curved sections of the human body such as limbs or a head. All the parameters studied (implant size, orientation, location, adjacent tissues and signal frequency) had a major effect on the SAR distribution and in certain cases high local EM fields arose near the implant. The SAR values increased most when the implant was on the skin and had a resonance length or diameter, i.e. about a third of the wavelength in tissues. The local peak SAR values increased even by a factor of 400-700 due to a pin or a ring. These highest values were reached in a limited volume close to the implant surface in almost all the studied cases. In contrast, without the implant the highest SAR values were generally reached on the skin surface. Mass averaged SAR(1 g) and SAR(10 g) values increased due to the implant even by a factor of 3 and 2, respectively. However, at typical power levels of mobile phones the enhancement is unlikely to

  7. Quantum plasmonics with a metal nanoparticle array

    NASA Astrophysics Data System (ADS)

    Lee, Changhyoup; Tame, Mark; Lim, James; Lee, Jinhyoung

    2012-06-01

    We investigate an array of metal nanoparticles as a channel for nanophotonic quantum communication and the generation of quantum plasmonic interference. We consider the transfer of quantum states, including single qubits as plasmonic wave packets, and highlight the necessity of a quantum-mechanical description by comparing the predictions of quantum theory with those of classical electromagnetic theory. The effects of loss in the metal are included, thus putting our investigation into a practical setting and enabling the quantification of the performance of realistic nanoparticle arrays as plasmonic quantum channels. We explore the interference of single plasmons, finding nonlinear absorption effects associated with the quantum properties of the plasmon excitations. This work highlights the benefits and drawbacks of using nanophotonic periodic systems for quantum plasmonic applications, such as quantum communication and the generation of quantum interference.

  8. Hybrid nanocomposite coatings from metal (Mg alloy)-drug deposited onto medical implant by laser adaptive ablation deposition technique

    NASA Astrophysics Data System (ADS)

    Serbezov, Valery; Sotirov, Sotir; Serbezov, Svetlin

    2013-03-01

    Drug-eluting medical implants are active implants whose function is to create healing effects. The current requirements for active medical coatings for Drug-eluting medical implants are to be biocompatible, biodegradable, polymer free, mechanically stable and enable a controlled release of one or more drugs and defined degradation. This brings hybrid nanocomposite coatings into focus especially in the field of cardiovascular implants. We studied the properties of Metal (Mg alloy)-Paclitaxel coatings obtained by novel Laser Adaptive Ablation Deposition Technique (LAAD) onto cardiovascular stents from 316 LVM stainless steel material. The morphology and topology of coatings were studied by Bright field / Fluorescence optical microscope and Scanning Electron Microscope (SEM). Comparative measurements were made of the morphology and topology of hybrid, polymer free nanocomposite coatings deposited by LAAD and polymerdrug coatings deposited by classical spray technique. The coatings obtained by LAAD are homogeneous without damages and cracks. Metal nanoparticles with sizes from 40 nm to 230 nm were obtained in drug matrixes. Energy Dispersive X-ray Spectroscopy (EDX) was used for identification of metal nanoparticles presence in hybrid nanocomposites coatings. The new technology opens up possibilities to obtain new hybrid nanocomposite coatings with applications in medicine, pharmacy and biochemistry.

  9. Nanoscale chirality in metal and semiconductor nanoparticles.

    PubMed

    Kumar, Jatish; Thomas, K George; Liz-Marzán, Luis M

    2016-10-18

    The field of chirality has recently seen a rejuvenation due to the observation of chirality in inorganic nanomaterials. The advancements in understanding the origin of nanoscale chirality and the potential applications of chiroptical nanomaterials in the areas of optics, catalysis and biosensing, among others, have opened up new avenues toward new concepts and design of novel materials. In this article, we review the concept of nanoscale chirality in metal nanoclusters and semiconductor quantum dots, then focus on recent experimental and theoretical advances in chiral metal nanoparticles and plasmonic chirality. Selected examples of potential applications and an outlook on the research on chiral nanomaterials are additionally provided.

  10. Nanoscale chirality in metal and semiconductor nanoparticles

    PubMed Central

    Thomas, K. George

    2016-01-01

    The field of chirality has recently seen a rejuvenation due to the observation of chirality in inorganic nanomaterials. The advancements in understanding the origin of nanoscale chirality and the potential applications of chiroptical nanomaterials in the areas of optics, catalysis and biosensing, among others, have opened up new avenues toward new concepts and design of novel materials. In this article, we review the concept of nanoscale chirality in metal nanoclusters and semiconductor quantum dots, then focus on recent experimental and theoretical advances in chiral metal nanoparticles and plasmonic chirality. Selected examples of potential applications and an outlook on the research on chiral nanomaterials are additionally provided. PMID:27752651

  11. The Effect of Metal Oxide on Nanoparticles from Thermite Reactions

    ERIC Educational Resources Information Center

    Moore, Lewis Ryan

    2006-01-01

    The purpose of this research was to determine how metal oxide used in a thermite reaction can impact the production of nanoparticles. The results showed the presence of nanoparticles (less than 1 micron in diameter) of at least one type produced by each metal oxide. The typical particles were metallic spheres, which ranged from 300 nanometers in…

  12. Screening Methods for Metal-Containing Nanoparticles in Water

    EPA Science Inventory

    Screening-level analysis of water for metal-containing nanoparticles is achieved with single particle-inductively coupled plasma mass spectrometry (SP-ICPMS). This method measures both the concentration of nanoparticles containing an analyte metal and the mass of the metal in eac...

  13. Broad-beam, high current, metal ion implantation facility

    SciTech Connect

    Brown, I.G.; Dickinson, M.R.; Galvin, J.E.; Godechot, X.; MacGill, R.A.

    1990-07-01

    We have developed a high current metal ion implantation facility with which high current beams of virtually all the solid metals of the Periodic Table can be produced. The facility makes use of a metal vapor vacuum arc ion source which is operated in a pulsed mode, with pulse width 0.25 ms and repetition rate up to 100 pps. Beam extraction voltage is up to 100 kV, corresponding to an ion energy of up to several hundred keV because of the ion charge state multiplicity; beam current is up to several Amperes peak and around 10 mA time averaged delivered onto target. Implantation is done in a broad-beam mode, with a direct line-of-sight from ion source to target. Here we describe the facility and some of the implants that have been carried out using it, including the seeding' of silicon wafers prior to CVD with titanium, palladium or tungsten, the formation of buried iridium silicide layers, and actinide (uranium and thorium) doping of III-V compounds. 16 refs., 6 figs.

  14. Exploring the potential of metallic nanoparticles within synthetic biology.

    PubMed

    Edmundson, Matthew C; Capeness, Michael; Horsfall, Louise

    2014-12-25

    The fields of metallic nanoparticle study and synthetic biology have a great deal to offer one another. Metallic nanoparticles as a class of material have many useful properties. Their small size allows for more points of contact than would be the case with a similar bulk compound, making nanoparticles excellent candidates for catalysts or for when increased levels of binding are required. Some nanoparticles have unique optical qualities, making them well suited as sensors, while others display para-magnetism, useful in medical imaging, especially by magnetic resonance imaging (MRI). Many of these metallic nanoparticles could be used in creating tools for synthetic biology, and conversely the use of synthetic biology could itself be utilised to create nanoparticle tools. Examples given here include the potential use of quantum dots (QDs) and gold nanoparticles as sensing mechanisms in synthetic biology, and the use of synthetic biology to create nanoparticle-sensing devices based on current methods of detecting metals and metalloids such as arsenate. There are a number of organisms which are able to produce a range of metallic nanoparticles naturally, such as species of the fungus Phoma which produces anti-microbial silver nanoparticles. The biological synthesis of nanoparticles may have many advantages over their more traditional industrial synthesis. If the proteins involved in biological nanoparticle synthesis can be put into a suitable bacterial chassis then they might be manipulated and the pathways engineered in order to produce more valuable nanoparticles.

  15. Effect of ion implantation on the tribology of metal-on-metal hip prostheses.

    PubMed

    Bowsher, John G; Hussain, Azad; Williams, Paul; Nevelos, Jim; Shelton, Julia C

    2004-12-01

    Nitrogen ion implantation (which considerably hardens the surface of the bearing) may represent one possible method of reducing the wear of metal-on-metal (MOM) hip bearings. Currently there are no ion-implanted MOM bearings used clinically. Therefore a physiological hip simulator test was undertaken using standard test conditions, and the results compared to previous studies using the same methods. N2-ion implantation of high carbon cast Co-Cr-Mo-on-Co-Cr-Mo hip prostheses increased wear by 2-fold during the aggressive running-in phase compared to untreated bearing surfaces, plus showing no wear reductions during steady-state conditions. Although 2 specimens were considered in the current study, it would appear that ion implantation has no clinical benefit for MOM.

  16. Calibration of radiographs by a reference metal ball affects preoperative selection of implant size.

    PubMed

    Schropp, Lars; Stavropoulos, Andreas; Gotfredsen, Erik; Wenzel, Ann

    2009-12-01

    The aim was to evaluate the impact of a reference ball for calibration of periapical and panoramic radiographs on preoperative selection of implant size for three implant systems. Presurgical digital radiographs (70 panoramic, 43 periapical) from 70 patients scheduled for single-tooth implant treatment, recorded with a metal ball placed in the edentulous area, were evaluated by three observers with the intent to select the appropriate implant size. Four reference marks corresponding to the margins of the metal ball were manually placed on the digital image by means of computer software. Additionally, an implant with proper dimensions for the respective site was outlined by manually placing four reference marks. The diameter of the metal ball and the unadjusted length and width of the implant were calculated. Implant size was adjusted according to a "standard" calibration method (SCM; magnification factor 1.25 in panoramic images and 1.05 in periapical images) and according to a reference ball calibration method (RCM; true magnification). Based on the unadjusted as well as the adjusted implant dimensions, the implant size was selected among those available in a given implant system. For periapical radiographs, when comparing SCM and RCM with unadjusted implant dimensions, implant size changed in 42% and 58%, respectively. When comparing SCM and RCM, implant size changed in 24%. For panoramic radiographs, comparing SCM and RCM changed implant size in 48%. The use of a reference metal ball for calibration of periapical and panoramic radiographs when selecting implant size during treatment planning might be advantageous.

  17. Silicon nanocrystal-noble metal hybrid nanoparticles

    NASA Astrophysics Data System (ADS)

    Sugimoto, H.; Fujii, M.; Imakita, K.

    2016-05-01

    We report a novel and facile self-limiting synthesis route of silicon nanocrystal (Si NC)-based colloidally stable semiconductor-metal (gold, silver and platinum) hybrid nanoparticles (NPs). For the formation of hybrid NPs, we employ ligand-free colloidal Si NCs with heavily boron (B) and phosphorus (P) doped shells. By simply mixing B and P codoped colloidal Si NCs with metal salts, hybrid NPs consisting of metal cores and Si NC shells are spontaneously formed. We demonstrate the synthesis of highly uniform and size controllable hybrid NPs. It is shown that codoped Si NCs act as a reducing agent for metal salts and also as a protecting layer to stop metal NP growth. The process is thus self-limiting. The development of a variety of Si NC-based hybrid NPs is a promising first step for the design of biocompatible multifunctional NPs with broad material choices for biosensing, bioimaging and solar energy conversion.We report a novel and facile self-limiting synthesis route of silicon nanocrystal (Si NC)-based colloidally stable semiconductor-metal (gold, silver and platinum) hybrid nanoparticles (NPs). For the formation of hybrid NPs, we employ ligand-free colloidal Si NCs with heavily boron (B) and phosphorus (P) doped shells. By simply mixing B and P codoped colloidal Si NCs with metal salts, hybrid NPs consisting of metal cores and Si NC shells are spontaneously formed. We demonstrate the synthesis of highly uniform and size controllable hybrid NPs. It is shown that codoped Si NCs act as a reducing agent for metal salts and also as a protecting layer to stop metal NP growth. The process is thus self-limiting. The development of a variety of Si NC-based hybrid NPs is a promising first step for the design of biocompatible multifunctional NPs with broad material choices for biosensing, bioimaging and solar energy conversion. Electronic supplementary information (ESI) available: Additional TEM images and extinction spectra of Si-metal hybrid NPs are shown in Fig. S1

  18. “Green” Nanotechnologies: Synthesis of Metal Nanoparticles Using Plants

    PubMed Central

    Makarov, V. V.; Love, A. J.; Sinitsyna, O. V.; Makarova, S. S.; Yaminsky, I. V.; Taliansky, M. E.; Kalinina, N. O.

    2014-01-01

    While metal nanoparticles are being increasingly used in many sectors of the economy, there is growing interest in the biological and environmental safety of their production. The main methods for nanoparticle production are chemical and physical approaches that are often costly and potentially harmful to the environment. The present review is devoted to the possibility of metal nanoparticle synthesis using plant extracts. This approach has been actively pursued in recent years as an alternative, efficient, inexpensive, and environmentally safe method for producing nanoparticles with specified properties. This review provides a detailed analysis of the various factors affecting the morphology, size, and yield of metal nanoparticles. The main focus is on the role of the natural plant biomolecules involved in the bioreduction of metal salts during the nanoparticle synthesis. Examples of effective use of exogenous biomatrices (peptides, proteins, and viral particles) to obtain nanoparticles in plant extracts are discussed. PMID:24772325

  19. Tailored SERS substrates obtained with cathodic arc plasma ion implantation of gold nanoparticles into a polymer matrix.

    PubMed

    Ferreira, Jacqueline; Teixeira, Fernanda S; Zanatta, Antonio R; Salvadori, Maria C; Gordon, Reuven; Oliveira, Osvaldo N

    2012-02-14

    This manuscript reports on the fabrication of plasmonic substrates using cathodic arc plasma ion implantation, in addition to their performance as SERS substrates. The technique allows for the incorporation of a wide layer of metallic nanoparticles into a polymer matrix, such as PMMA. The ability to pattern different structures using the PMMA matrix is one of the main advantages of the fabrication method. This opens up new possibilities for obtaining tailored substrates with enhanced performance for SERS and other surface-enhanced spectroscopies, as well as for exploring the basic physics of patterned metal nanostructures. The architecture of the SERS-active substrate was varied using three adsorption strategies for incorporating a laser dye (rhodamine): alongside the nanoparticles into the polymer matrix, during the polymer cure and within nanoholes lithographed on the polymer. As a proof-of-concept, we obtained the SERS spectra of rhodamine for the three types of substrates. The hypothesis of incorporation of rhodamine molecules into the polymer matrix during the cathodic arc plasma ion implantation was supported by FDTD (Finite-Difference Time-Domain) simulations. In the case of arrays of nanoholes, rhodamine molecules could be adsorbed directly on the gold surface, then yielding a well-resolved SERS spectrum for a small amount of analyte owing to the short-range interactions and the large longitudinal field component inside the nanoholes. The results shown here demonstrate that the approach based on ion implantation can be adapted to produce reproducible tailored substrates for SERS and other surface-enhanced spectroscopies.

  20. Surface energy of metal alloy nanoparticles

    NASA Astrophysics Data System (ADS)

    Takrori, Fahed M.; Ayyad, Ahmed

    2017-04-01

    The measurement of surface energy of alloy nanoparticles experimentally is still a challenge therefore theoretical work is necessary to estimate its value. In continuation of our previous work on the calculation of the surface energy of pure metallic nanoparticles we have extended our work to calculate the surface energy of different alloy systems, namely, Co-Ni, Au-Cu, Cu-Al, Cu-Mg and Mo-Cs binary alloys. It is shown that the surface energy of metallic binary alloy decreases with decreasing particle size approaching relatively small values at small sizes. When both metals in the alloy obey the Hume-Rothery rules, the difference in the surface energy is small at the macroscopic as well as in the nano-scale. However when the alloy deviated from these rules the difference in surface energy is large in the macroscopic and in the nano scales. Interestingly when solid solution formation is not possible at the macroscopic scale according to the Hume-Rothery rules, it is shown it may form at the nano-scale. To our knowledge these findings here are presented for the first time and is challenging from fundamental as well as technological point of views.

  1. Dynamics of Faceted Nanoparticles Formation in a Crystalline Matrix During Ion Implantation Processing.

    PubMed

    Li, Kun-Dar

    2016-02-01

    The faceted nanoparticle synthesized by ion implantation, such as Zn, Cu or Ag nanoparticles, is one of the promising materials for the next generation of optical devices. To understand and better control the manufacturing processes of ion implantation, a theoretical model is applied to investigate the formation and evolution of faceted nanoparticles under various experimental conditions of implantation processing. In this study, the mechanisms of the anisotropic interfacial energy and kinetics with different ion distributions are taken into consideration to demonstrate the role of the crystallographic symmetry, ion energy and temperature on the faceted nanoparticles formation in a crystalline matrix. As presented in the numerical results, the morphological shape of the nanoparticles is mainly affected by the crystallographic symmetry, while the distribution of the precipitates is principally determined by the ion energy. For the condition of high-temperature implantation, a high mobility of ions causes the characteristic length of nanostructures to increase and creates a coarsening morphology of nanoparticles. It is attributed to a longer diffusion distance during the nucleation and growth processes. This model can be widely used for the predictions of the nanostructures formation with various ion implantation processes.

  2. Photoactivable caps for reactive metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Patel, Ashish

    The synthesis and stabilization of reactive metal nanoparticles is often challenging under normal atmospheric conditions. This problem can be alleviated by capping and passivation. Our lab has focused on forming polymer coatings on the surface of reactive metal nanoparticles. We discovered a convenient and effective route for stabilization of aluminum nanoparticles (Al NPs), which uses the nascent metal core as a polymerization initiator for various organic monomers. In our previous work, we used this method to passivate the Al NPs using variety of epoxides and copolymers of epoxides and alkenes. These products have demonstrated air stability for weeks to months with little to no degradation in the active Al content. Since our previously synthesized Al NP's were not beneficial for rapid and efficient thermodynamic access to the active Al core, our goal was find polymers that could easily be photochemically activated to enhance such access. Since poly(methyl methacrylate) (PMMA) has photodegrading properties, we used PMMA as a capping agent to passivate Al NPs. In this work, we present capping and stabilization of Al NPs with PMMA, and also with 1,2-epoxyhexane/ PMMA. In our previous work, we increased the stability of Al NP capped with 1,2-epoxy-9-decene by adding 1,13-tetradecadiene as a cross-linker. Here, we used the methyl methacrylate (MMA) monomer as cross-linker for Al NP capped with 1,2-epoxy-9-decene. We have also used the MMA as capping agent. We use powder x-ray diffractametry (PXRD), differential scanning calorimetry (DSC), and thermogravity analysis (TGA) to confirm the presence of elemental Al and ATR-FTIR to confirm the presence of polymers.

  3. Optical Properties of Controlled Nanoscale Assemblies of Metal Nanoparticles

    NASA Astrophysics Data System (ADS)

    Westcott, S. L.; Oldenburg, S. J.; Lee, T. R.; Halas, N. J.

    1998-03-01

    The optical response of a metal nanoparticle in an assembly of nanoparticles is affected by scattering from the other nanoparticles in the assembly. In general, this interaction leads to the appearance of lower energy peaks in the absorption spectrum with their location dependent on the geometry of the assembly(M. Quinten and U. Kreibig, Surface Science 172), 557 (1986).. We construct two types of assemblies using functionalized silica nanoparticles as substrates for the immobilization of metal nanoparticles. First, surprisingly monodisperse clusters of small gold nanoparticles spontaneously form and attach to the silica nanoparticles under appropriate solvent conditions. Second, controlled aggregates of metal nanoparticles are synthesized using bifunctional molecular linkers in a step-by-step procedure. The distances between the constituent metallic nanoparticles, as well as the electronic properties of the region between the nanoparticles, are controlled by the choice of bifunctional molecular linker. As a result of either assembly method, metallic nanoparticles can be brought sufficiently close to each other so that interactions may be observed.

  4. Electromagnetic Compatibility Testing of Implantable Neurostimulators Exposed to Metal Detectors

    PubMed Central

    Seidman, Seth J; Kainz, Wolfgang; Casamento, Jon; Witters, Donald

    2010-01-01

    This paper presents results of electromagnetic compatibility (EMC) testing of three implantable neurostimulators exposed to the magnetic fields emitted from several walk-through and hand-held metal detectors. The motivation behind this testing comes from numerous adverse event reports involving active implantable medical devices (AIMDs) and security systems that have been received by the Food and Drug Administration (FDA). EMC testing was performed using three neurostimulators exposed to the emissions from 12 walk-through metal detectors (WTMDs) and 32 hand-held metal detectors (HHMDs). Emission measurements were performed on all HHMDs and WTMDs and summary data is presented. Results from the EMC testing indicate possible electromagnetic interference (EMI) between one of the neurostimulators and one WTMD and indicate that EMI between the three neurostimulators and HHMDs is unlikely. The results suggest that worst case situations for EMC testing are hard to predict and testing all major medical device modes and setting parameters are necessary to understand and characterize the EMC of AIMDs. PMID:20448818

  5. Z-scan study of nonlinear absorption of gold nano-particles prepared by ion implantation in various types of silicate glasses

    NASA Astrophysics Data System (ADS)

    Husinsky, W.; Ajami, A.; Nekvindova, P.; Svecova, B.; Pesicka, J.; Janecek, M.

    2012-05-01

    Metal nano-clusters composite glasses synthesized by ion implantation have been shown as promising nonlinear photonic material. In this paper, we report on the nonlinear absorption measurements of gold nano-particles implanted in four structurally different types of silicate glasses. All targets containing gold nano-particles in a layer 500 nm under the surface of the glass have been prepared by ion implantation with subsequent annealing. The targets were characterized by UV-VIS absorption spectroscopy, transmission electron microscopy (TEM) and by the Z-scan technique. The resulting nano-particles differed in size, range of particle size and shape as well as depth distribution characteristic for glasses with different chemical compositions. With the Z-scan technique, it can be shown that the nano-particles produced in silicate glasses exhibit substantial two-photon absorption (TPA). The TPA coefficient differed depending on size, shape, and depth distribution of the metal nano-clusters and the structure and composition of the glass substrates. The highest TPA coefficient (16.25 cm/GW) was found for the glass BK7 in which the largest non-spherical nano-particles have been observed in the thinnest layer.

  6. The development of a biological interface for transition metal implants

    NASA Astrophysics Data System (ADS)

    Melton, Kim R.

    The specific goal of this research was to develop an in vitro model for a root-form endosseous dental implant that contains a periodontal ligament and that is biologically integratable into alveolar bone. This objective was based on the following two hypotheses. (1) The chemical attachment of extracellular matrix proteins to the surface of transition metals increases the number of fibroblast cells attached to the surface of the metal. (2) The chemical attachment of extracellular matrix proteins to the surface of transition metals increases the strength of the fibroblast cell attachment to the surface of the metal. The model needed to have a well-controlled surface that was reproducible. Thus, a layer of Au was deposited over a Ti base, and dithiobis(succinimidylpropionate) (DSP) a chemical containing disulfide groups was adsorbed to the Au. Next, extracellular matrix proteins which are periodontal ligament components were attached to the free end group of the chemical that was adsorbed to the Au. This surface served as an attachment substrate on which additional periodontal ligament components such as fibroblast cells could grow. From this model a new implant interface may be developed. This model was tested using the following polypeptides; collagen type I, collagen type IV, fibronectin, and poly-D-lysine. L929 cells were grown on Ti, Ti + Au, Ti + Au + polypeptide, and Ti + Au + DSP + polypeptide. After 72 hours, the live cells were stained with neutral red. The substrates were then subjected to increasing centrifugal forces. The viable stained cells were fixed onto the substrates and cells were counted. The hypotheses were proven for three polypeptides: fibronectin, collagen type I, and poly-D-lysine. The strongest attachment was found with collagen type I. Collagen type IV did not provide any advantage for attachment over uncoated transition metals.

  7. Materials analyses and electrochemical impedance of implantable metal electrodes.

    PubMed

    Howlader, Matiar M R; Ul Alam, Arif; Sharma, Rahul P; Deen, M Jamal

    2015-04-21

    Implantable electrodes with high flexibility, high mechanical fixation and low electrochemical impedance are desirable for neuromuscular activation because they provide safe, effective and stable stimulation. In this paper, we report on detailed materials and electrical analyses of three metal implantable electrodes - gold (Au), platinum (Pt) and titanium (Ti) - using X-ray photoelectron spectroscopy (XPS), scanning acoustic microscopy, drop shape analysis and electrochemical impedance spectroscopy. We investigated the cause of changes in electrochemical impedance of long-term immersed Au, Pt and Ti electrodes on liquid crystal polymers (LCPs) in phosphate buffered saline (PBS). We analyzed the surface wettability, surface and interface defects and the elemental depth profile of the electrode-adhesion layers on the LCP. The impedance of the electrodes decreased at lower frequencies, but increased at higher frequencies compared with that of the short-term immersion. The increase of impedances was influenced by the oxidation of the electrode/adhesion-layers that affected the double layer capacitance behavior of the electrode/PBS. The oxidation of the adhesion layer for all the electrodes was confirmed by XPS. Alkali ions (sodium) were adsorbed on the Au and Pt surfaces, but diffused into the Ti electrode and LCPs. The Pt electrode showed a higher sensitivity to surface and interface defects than that of Ti and Au electrodes. These findings may be useful when designing electrodes for long-term implantable devices.

  8. Metal Nanoparticle Catalysts for Carbon Nanotube Growth

    NASA Technical Reports Server (NTRS)

    Pierce, Benjamin F.

    2003-01-01

    Work this summer involved and new and unique process for producing the metal nanoparticle catalysts needed for carbon nanotube (CNT) growth. There are many applications attributed to CNT's, and their properties have deemed them to be a hot spot in research today. Many groups have demonstrated the versatility in CNT's by exploring a wide spectrum of roles that these nanotubes are able to fill. A short list of such promising applications are: nanoscaled electronic circuitry, storage media, chemical sensors, microscope enhancement, and coating reinforcement. Different methods have been used to grow these CNT's. Some examples are laser ablation, flame synthesis, or furnace synthesis. Every single approach requires the presence of a metal catalyst (Fe, Co, and Ni are among the best) that is small enough to produce a CNT. Herein lies the uniqueness of this work. Microemulsions (containing inverse micelles) were used to generate these metal particles for subsequent CNT growth. The goal of this summer work was basically to accomplish as much preliminary work as possible. I strived to pinpoint which variable (experimental process, metal product, substrate, method of application, CVD conditions, etc.) was the determining factor in the results. The resulting SEM images were sufficient for the appropriate comparisons to be made. The future work of this project consists of the optimization of the more promising experimental procedures and further exploration onto what exactly dictated the results.

  9. Development and Applications of Porous Tantalum Trabecular Metal Enhanced Titanium Dental Implants

    PubMed Central

    Bencharit, Sompop; Byrd, Warren C.; Altarawneh, Sandra; Hosseini, Bashir; Leong, Austin; Reside, Glenn; Morelli, Thiago; Offenbacher, Steven

    2013-01-01

    Statement of Problem Porous tantalum trabecular metal has recently been incorporated in titanium dental implants as a new form of implant surface enhancement. However, there is little information on the applications of this material in implant dentistry. Methods We, therefore review the current literature on the basic science and clinical uses of this material. Results Porous tantalum metal is used to improve the contact between osseous structure and dental implants; and therefore presumably facilitate osseointegration. Success of porous tantalum metal in orthopedic implants led to the incorporation of porous tantalum metal in the design of root-from endosseous titanium implants. The porous tantalum three-dimensional enhancement of titanium dental implant surface allows for combining bone ongrowth together with bone ingrowth, or osseoincorporation. While little is known about the biological aspect of the porous tantalum in the oral cavity, there seems to be several possible advantages of this implant design. This article reviews the biological aspects of porous tantalum enhanced titanium dental implants, in particular the effects of anatomical consideration and oral environment to implant designs. Conclusions We propose here possible clinical situations and applications for this type of dental implant. Advantages and disadvantages of the implants as well as needed future clinical studies are discussed. PMID:23527899

  10. Evaluation of metallic osseous implants with nuclear medicine

    SciTech Connect

    Wellman, H.N.; Schauwecker, D.S.; Capello, W.N.

    1988-04-01

    Nuclear medicine has proven to have a valuable role in the evaluation of osseous metallic implants, particularly with joint prostheses, but can assist with evaluation of other appliances as well. The nuclear arthrogram has become an invaluable adjunct to simultaneously performed radiographic contrast arthrography. This application has been best evaluated in what is one of the most common of orthopedic prosthesis problems, namely, loosening of total hip prostheses. Experience indicates that both sensitivity and specificity of loosening of the femoral component can be increased to over 90% through combined use of nuclear with radiographic contrast arthrography. Furthermore the combination of routine skeletal scintimaging with the nuclear arthrogram adds a significant dimension to precise localizing of the nuclear arthrographics agent In-111 chloride. Nuclear medicine also plays an important role in further evaluating the presence of infection associated with metallic implants with In-111 WBC preparations being superior to Ga-67 as the radiopharmaceutical tracer. Infection has been detected with a sensitivity of 73% and a specificity of 93% in our series using combined In-111 WBC and simultaneous skeletal imaging with conventional Tc-99m MDP. Acute infections are more readily identifiable than chronic in association with prostheses. 29 references.

  11. Biocompatibility of transition metal-substituted cobalt ferrite nanoparticles

    NASA Astrophysics Data System (ADS)

    Sanpo, Noppakun; Tharajak, Jirasak; Li, Yuncang; Berndt, Christopher C.; Wen, Cuie; Wang, James

    2014-07-01

    Transition metals of copper, zinc, manganese, and nickel were substituted into cobalt ferrite nanoparticles via a sol-gel route using citric acid as a chelating agent. The microstructure and elemental compositions of the nanoparticles were characterized using scanning electron microscopy combined with energy dispersive X-ray spectroscopy. The particle size of the nanoparticles was investigated using particle size analyzer, and the zeta potentials were measured using zeta potential analyzer. The phase components of the synthesized transition metal-substituted cobalt ferrite nanoparticles were studied using Raman spectroscopy. The biocompatibility of the nanoparticles was assessed using osteoblast-like cells. Results indicated that the substitution of transition metals strongly influences the physical, chemical properties, and biocompatibility of the cobalt ferrite nanoparticles.

  12. Fate and toxicity of metallic and metal-containing nanoparticles for biomedical applications.

    PubMed

    Li, Yu-Feng; Chen, Chunying

    2011-11-04

    It is important to obtain a better understanding of the uptake, trafficking, pharmacokinetics, clearance, and role of nanomaterials in biological systems, so that their possible undesirable effects can be avoided. A number of metallic or metal-containing nanomaterials, such as gold nanoparticles and nanorods, quantum dots, iron oxides nanoparticles, and endohedral metallofullerenes, have already been or will soon become very promising for biomedical applications. This review presents a summary of currently available data on the fate and toxicity of these metallic or metal-containing nanoparticles based on animal studies. Several issues regarding the nanotoxicity assessment and future directions on the study of the fate of these nanoparticles are also proposed.

  13. Marine microorganisms as potential biofactories for synthesis of metallic nanoparticles.

    PubMed

    Manivasagan, Panchanathan; Nam, Seung Yun; Oh, Junghwan

    2016-11-01

    The use of marine microorganisms as potential biofactories for green synthesis of metallic nanoparticles is a relatively new field of research with considerable prospects. This method is eco-friendly, time saving, and inexpensive and can be easily scaled up for large-scale synthesis. The increasing need to develop simple, nontoxic, clean, and environmentally safe production methods for nanoparticles and to decrease environmental impact, minimize waste, and increase energy productivity has become important in this field. Marine microorganisms are tiny organisms that live in marine ecosystems and account for >98% of biomass of the world's ocean. Marine microorganisms synthesize metallic nanoparticles either intracellularly or extracellularly. Marine microbially-produced metallic nanoparticles have received considerable attention in recent years because of their expected impact on various applications such as medicine, energy, electronic, and space industries. The present review discusses marine microorganisms as potential biofactories for the green synthesis of metallic nanoparticles and their potential applications.

  14. Shape Evolution of Metal Nanoparticles in Water Vapor Environment.

    PubMed

    Zhu, Beien; Xu, Zhen; Wang, Chunlei; Gao, Yi

    2016-04-13

    The structures of the metal nanoparticles are crucial for their catalytic activities. How to understand and even control the shape evolution of nanoparticles under reaction condition is a big challenge in heterogeneous catalysis. It has been proved that many reactive gases hold the capability of changing the structures and properties of metal nanoparticles. One interesting question is whether water vapor, such a ubiquitous environment, could induce the shape evolution of metal nanoparticles. So far this question has not received enough attention yet. In this work, we developed a model based on the density functional theory, the Wulff construction, and the Langmuir adsorption isotherm to explore the shape of metal nanoparticle at given temperature and water vapor pressure. By this model, we show clearly that water vapor could notably increase the fraction of (110) facets and decrease that of (111) facets for 3-8 nm Cu nanoparticles, which is perfectly consistent with the experimental observations. Further investigations indicate the water vapor has different effects on the different metal species (Cu, Au, Pt, and Pd). This work not only helps to understand the water vapor effect on the structures of metal nanoparticles but also proposes a simple but effective model to predict the shape of nanoparticles in certain environment.

  15. Materials design considerations involved in the fabrication of implantable bionics by metallization of ceramic substrates.

    PubMed

    Patel, Sunil; Guenther, Thomas; Dodds, Christopher W D; Kolke, Sergej; Privat, Karen L; Matteucci, Paul B; Suaning, Gregg J

    2013-01-01

    The Pt metallization of co-fired Al2O3/SiO2 substrates containing Pt feedthroughs was shown to be a suitable means to construct implantable bionics. The use of forge welding to join an electrode to such a metallized feedthrough was demonstrated and subsequently evaluated through the use of metallography and electron microscopy. Metallurgical phenomena involved in forge welding relevant to the fabrication of all types of biomedical implants are discussed within this paper. The affect of thermal profiles used in brazing or welding to build implantable devices from metal components is analysed and the case for considered selection of alloys in implant design is put forward.

  16. Metal ion implantation for large scale surface modification

    SciTech Connect

    Brown, I.G.

    1992-10-01

    Intense energetic beams of metal ions can be produced by using a metal vapor vacuum arc as the plasma discharge from which the ion beam is formed. We have developed a number of ion sources of this kind and have built a metal ion implantation facility which can produce repetitively pulsed ion beams with mean ion energy up to several hundred key, pulsed beam current of more than an ampere, and time averaged current of several tens of milliamperes delivered onto a downstream target. We've also done some preliminary work on scaling up this technology to very large size. For example, a 50-cm diameter (2000 cm[sup 2]) set of beam formation electrodes was used to produce a pulsed titanium beam with ion current over 7 amperes at a mean ion energy of 100 key. Separately, a dc embodiment has been used to produce a dc titanium ion beam with current over 600 mA, power supply limited in this work, and up to 6 amperes of dc plasma ion current was maintained for over an hour. In a related program we've developed a plasma immersion method for applying thin metallic and compound films in which the added species is atomically mixed to the substrate. By adding a gas flow to the process, well-bonded compound films can also be formed; metallic films and multilayers as well as oxides and nitrides with mixed transition zones some hundreds of angstroms thick have been synthesized. Here we outline these parallel metal-plasma-based research programs and describe the hardware that we've developed and some of the surface modification research that we've done with it.

  17. Fabrication of composite based on GeSi with Ag nanoparticles using ion implantation

    NASA Astrophysics Data System (ADS)

    Batalov, R. I.; Vorobev, V. V.; Nuzhdin, V. I.; Valeev, V. F.; Bayazitov, R. M.; Lyadov, N. M.; Osin, Yu. N.; Stepanov, A. L.

    2016-12-01

    Comparative analysis of the structural and optical properties of composite layers fabricated with the aid of implantation of single-crystalline silicon ( c-Si) using Ge+ (40 keV/1 × 1017 ions/cm2) and Ag+ (30 keV/1.5 × 1017 ions/cm2) ions and sequential irradiation using Ge+ and Ag+ ions is presented. The implantation of the Ge+ ions leads to the formation of Ge: Si fine-grain amorphous surface layer with a thickness of 60 nm and a grain size of 20-40 nm. The implantation of c-Si using Ag+ ions results in the formation of submicron porous amorphous a-Si structure with a thickness of about 50 nm containing ion-synthesized Ag nanoparticles. The penetration of the Ag+ ions in the Ge: Si layer stimulates the formation of pores with Ag nanoparticles with more uniform size distribution. The reflection spectra of the implanted Ag: Si and Ag: GeSi layers exhibit a sharp decrease in the intensity in the UV (220-420 nm) spectral interval relative to the intensity of c-Si by more than 50% owing to the amorphization and structuring of surface. The formation of Ag nanoparticles in the implanted layers gives rise to a selective band of the plasmon resonance at a wavelength of about 820 nm in the optical spectra. Technological methods for fabrication of a composite based on GeSi with Ag nanoparticles are demonstrated in practice.

  18. Lubrication and friction prediction in metal-on-metal hip implants.

    PubMed

    Wang, F C; Brockett, C; Williams, S; Udofia, I; Fisher, J; Jin, Z M

    2008-03-07

    A general methodology of mixed lubrication analysis and friction prediction for a conforming spherical bearing in hip implants was developed, with particular reference to a typical metal-on-metal hip replacement. Experimental measurement of frictional torque for a similar implant was carried out to validate the theoretical prediction. A ball-in-socket configuration was adopted to represent the articulation between the femoral head and the acetabular cup under cyclic operating conditions of representative load and motion. The mixed lubrication model presented in this study was first applied to identify the contact characteristics on the bearing surfaces, consisting of both fluid-film and boundary lubricated regions. The boundary lubricated contact was assumed to occur when the predicted fluid film thickness was less than a typical boundary protein layer absorbed on the bearing surfaces. Subsequently, the friction was predicted from the fluid-film lubricated region with viscous shearing due to both Couette and Poiseuille flows and the boundary protein layer contact region with a constant coefficient of friction. The predicted frictional torque of the typical metal-on-metal hip joint implant was compared with the experimental measurement conducted in a functional hip simulator and a reasonably good agreement was found. The mixed lubrication regime was found to be dominant for the conditions considered. Although the percentage of the boundary lubricated region was quite small, the corresponding contribution to friction was quite large and the resultant friction factor was quite high.

  19. Toxicity of cobalt-chromium nanoparticles released from a resurfacing hip implant and cobalt ions on primary human lymphocytes in vitro.

    PubMed

    Posada, Olga M; Tate, R J; Grant, M H

    2015-06-01

    Adverse tissue responses to prostheses wear particles and released ions are important contributors to hip implant failure. In implant-related adverse reactions T-lymphocytes play a prominent role in sustaining the chronic inflammatory response. To further understand the involvement of lymphocytes in metal-on-metal (MoM) implant failure, primary human lymphocytes were isolated and treated with cobalt-chromium (Co-Cr) wear debris and Co ions, individually, and in combination, for 24, 48 and 120 h. There was a significant increase in cell number where debris was present, as measured by the Neutral Red assay. Interleukin-6 (IL-6), interferon-γ (IFN-γ) and tumour necrosis factor-α (TNF-α) secretion levels significantly decreased in the presence of metal particles, as measured by ELISA. Interleukin-2 (IL-2) secretion levels were significantly decreased by both debris and Co ions. Flow cytometry analysis showed that the metal nanoparticles induced a significant increase in apoptosis after 48-h exposure. This investigation showed that prolonged exposure (120 h) to metal debris induces lymphocyte proliferation, suggesting that activation of resting lymphocytes may have occurred. Although cytokine production was affected mainly by metal debris, cobalt toxicity may also modulate IL-2 secretion, and even Co ion concentrations below the MHRA guideline levels (7 ppb) may contribute to the impairment of immune regulation in vivo in patients with MoM implants.

  20. Paper surfaces for metal nanoparticle inkjet printing

    NASA Astrophysics Data System (ADS)

    Öhlund, Thomas; Örtegren, Jonas; Forsberg, Sven; Nilsson, Hans-Erik

    2012-10-01

    The widespread usage of paper and board offer largely unexploited possibilities for printed electronics applications. Reliability and performance of printed devices on comparatively rough and inhomogenous surfaces of paper does however pose challenges. Silver nanoparticle ink has been deposited on ten various paper substrates by inkjet printing. The papers are commercially available, and selected over a range of different types and construction. A smooth nonporous polyimide film was included as a nonporous reference substrate. The substrates have been characterized in terms of porosity, absorption rate, apparent surface energy, surface roughness and material content. The electrical conductivity of the resulting printed films have been measured after drying at 60 °C and again after additional curing at 110 °C. A qualitative analysis of the conductivity differences on the different substrates based on surface characterization and SEM examination is presented. Measurable parameters of importance to the final conductivity are pointed out, some of which are crucial to achieve conductivity. When certain criteria of the surfaces are met, paper media can be used as low cost, but comparably high performance substrates for metal nanoparticle inks in printed electronics applications.

  1. Asymmetric light reflectance from metal nanoparticle arrays on dielectric surfaces

    NASA Astrophysics Data System (ADS)

    Huang, K.; Pan, W.; Zhu, J. F.; Li, J. C.; Gao, N.; Liu, C.; Ji, L.; Yu, E. T.; Kang, J. Y.

    2015-12-01

    Asymmetric light reflectance associated with localized surface plasmons excited in metal nanoparticles on a quartz substrate is observed and analyzed. This phenomenon is explained by the superposition of two waves, the wave reflected by the air/quartz interface and that reflected by the metal nanoparticles, and the resulting interference effects. Far field behavior investigation suggests that zero reflection can be achieved by optimizing the density of metal nanoparticles. Near field behavior investigation suggests that the coupling efficiency of localized surface plasmon can be additionally enhanced by separating the metal NPs from substrates using a thin film with refractive index smaller than the substrate. The latter behavior is confirmed via surface-enhanced Raman spectroscopy studies using metal nanoparticles on Si/SiO2 substrates.

  2. Asymmetric light reflectance from metal nanoparticle arrays on dielectric surfaces.

    PubMed

    Huang, K; Pan, W; Zhu, J F; Li, J C; Gao, N; Liu, C; Ji, L; Yu, E T; Kang, J Y

    2015-12-18

    Asymmetric light reflectance associated with localized surface plasmons excited in metal nanoparticles on a quartz substrate is observed and analyzed. This phenomenon is explained by the superposition of two waves, the wave reflected by the air/quartz interface and that reflected by the metal nanoparticles, and the resulting interference effects. Far field behavior investigation suggests that zero reflection can be achieved by optimizing the density of metal nanoparticles. Near field behavior investigation suggests that the coupling efficiency of localized surface plasmon can be additionally enhanced by separating the metal NPs from substrates using a thin film with refractive index smaller than the substrate. The latter behavior is confirmed via surface-enhanced Raman spectroscopy studies using metal nanoparticles on Si/SiO2 substrates.

  3. Interference between nanoparticles and metal homeostasis

    NASA Astrophysics Data System (ADS)

    Petit, A. N.; Aude Garcia, C.; Candéias, S.; Casanova, A.; Catty, P.; Charbonnier, P.; Chevallet, M.; Collin-Faure, V.; Cuillel, M.; Douki, T.; Herlin-Boime, N.; Lelong, C.; Luche, S.; Mintz, E.; Moulis, J. M.; Nivière, V.; Ollagnier de Choudens, S.; Rabilloud, T.; Ravanat, J. L.; Sauvaigo, S.; Carrière, M.; Michaud-Soret, I.

    2011-07-01

    The TiO2 nanoparticles (NPs) are now produced abundantly and widely used in a variety of consumer products. Due to the important increase in the production of TiO2-NPs, potential widespread exposure of humans and environment may occur during both the manufacturing process and final use. Therefore, the potential toxicity of TiO2-NPs on human health and environment has attracted particular attention. Unfortunately, the results of the large number of studies on the toxicity of TiO2-NPs differ significantly, mainly due to an incomplete characterization of the used nanomaterials in terms of size, shape and crystalline structure and to their unknown state of agglomeration/aggregation. The purpose of our project entitled NanoBioMet is to investigate if interferences between nanoparticles and metal homeostasis could be observed and to study the toxicity mechanisms of TiO2-NPs with well-characterized physicochemical parameters, using proteomic and molecular approaches. A perturbation of metal homeostasis will be evaluated upon TiO2-NPs exposure which could generate reactive oxygen species (ROS) production. Moreover, oxidative stress consequences such as DNA damage and lipid peroxidation will be studied. The toxicity of TiO2-NPs of different sizes and crystalline structures will be evaluated both in prokaryotic (E. coli) and eukaryotic cells (A549 human pneumocytes, macrophages, and hepatocytes). First results of the project will be presented concerning the dispersion of TiO2-NPs in bacterial medium, proteomic studies on total extracts of macrophages and genotoxicity on pneumocytes.

  4. Enhancement of Raman scattering from molecules placed near metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Barbiellini, B.

    2017-01-01

    Large Raman scattering cross sections from molecules on surfaces of metallic nanoparticles are described within a renormalization-group theory. In this approach the valence electrons of the molecules are embedded in an effective medium described by a dielectric function, which integrates out the effect of the plasmonic excitations of the metallic nanoparticles. The source of the enhanced photon inelastic scattering is produced by the resonant excitation of surface plasmons at the metallic nanoparticles. A similar theory has been successfully used to explain the resonant x-ray inelastic scattering and the behavior of nonlinear susceptibilities at the x-ray edges.

  5. Synthesis of Lithium Metal Oxide Nanoparticles by Induction Thermal Plasmas

    PubMed Central

    Tanaka, Manabu; Kageyama, Takuya; Sone, Hirotaka; Yoshida, Shuhei; Okamoto, Daisuke; Watanabe, Takayuki

    2016-01-01

    Lithium metal oxide nanoparticles were synthesized by induction thermal plasma. Four different systems—Li–Mn, Li–Cr, Li–Co, and Li–Ni—were compared to understand formation mechanism of Li–Me oxide nanoparticles in thermal plasma process. Analyses of X-ray diffractometry and electron microscopy showed that Li–Me oxide nanoparticles were successfully synthesized in Li–Mn, Li–Cr, and Li–Co systems. Spinel structured LiMn2O4 with truncated octahedral shape was formed. Layer structured LiCrO2 or LiCoO2 nanoparticles with polyhedral shapes were also synthesized in Li–Cr or Li–Co systems. By contrast, Li–Ni oxide nanoparticles were not synthesized in the Li–Ni system. Nucleation temperatures of each metal in the considered system were evaluated. The relationship between the nucleation temperature and melting and boiling points suggests that the melting points of metal oxides have a strong influence on the formation of lithium metal oxide nanoparticles. A lower melting temperature leads to a longer reaction time, resulting in a higher fraction of the lithium metal oxide nanoparticles in the prepared nanoparticles.

  6. Actinomycetes mediated biogenic synthesis of metal and metal oxide nanoparticles: Progress and challenges.

    PubMed

    Manimaran, Manickavelu; Kannabiran, Krishnan

    2017-03-07

    Actinomycetes mediated biogenic synthesis of metal nanoparticles and their antimicrobial activities are well documented. Actinomycetes facilitate both intracellular and extracellular metal nanoparticles synthesis and are efficient candidates for the production of polydispersed, stable and ultra-small size metal nanoparticles. Secondary metabolites and new chemical entities derived from actinomycetes have not been extensively studied for the synthesis of metal/ metal oxide nanoparticles. The present review focuses on biogenic synthesis of metal nanoparticles from actinomycetes and the scope for exploring actinomycetes derived compounds (enzymes, organics acids and bioactive compounds) as metal and metal oxide reducing agents for the synthesis of desired nanoparticles. This review also focuses on challenges faced in the applications nanoparticles and the methods to synthesise biogenic metal nanoparticles with desired physiochemical properties such as ultra-small size, large surface to mass ratio, high reactivity etc. Methods to evade their toxicity and unique interactions with biological systems to improve their chance as an alternative therapeutic agent in medical and pharmaceutical industry are also discussed. This article is protected by copyright. All rights reserved.

  7. DKG statement on the use of metal alloy discs for patch testing in suspected intolerance to metal implants.

    PubMed

    Thomas, Peter; Geier, Johannes; Dickel, Heinrich; Diepgen, Thomas; Hillen, Uwe; Kreft, Burkhard; Schnuch, Axel; Szliska, Christiane; Mahler, Vera

    2015-10-01

    Intolerance reactions to metal implants may be caused by metal allergy. However, prior to implantation, 'prophetic'/prophylactic patch testing should not be performed. Pre-implant patch testing should only be done to verify or exclude metal allergy in patients with a corresponding history. In case of implant-related complications - in particular following replacement arthroplasty - such as pain, effusion, skin lesions, reduced range of motion or implant loosening, orthopedic causes should be ruled out first. Workup of suspected metal implant allergy should then be done using the DKG standard series, which includes nickel, cobalt, and chromium preparations. Various studies assessing the usefulness of metal alloy discs for patch testing have shown this particular approach to be ineffective with respect to providing reliable information on metal allergy. Any positive reaction in such tests cannot be assigned to a specific metal contained within the alloy. Furthermore, there is a risk of broad and indiscriminate use of these readily available discs. Accordingly, given the lack of additional benefit compared to patch testing with standardized metal salt preparations, we do not recommend patch testing with metal alloy discs.

  8. Destructive Clustering of Metal Nanoparticles in Chalcogenide and Oxide Glassy Matrices.

    PubMed

    Shpotyuk, M V; Shpotyuk, O I; Cebulski, J; Kozyukhin, S

    2016-12-01

    The energetic χ-criterion is developed to parameterize difference in the origin of high-order optical non-linearity associated with metallic atoms (Cu, Ag, Au) embedded destructively in oxide- and chalcogenide glasses. Within this approach, it is unambiguously proved that covalent-bonded networks of soft semiconductor chalcogenides exemplified by binary As(Ge)-S(Se) glasses differ essentially from those typical for hard dielectric oxides like vitreous silica by impossibility to accommodate pure agglomerates of metallic nanoparticles. In an excellence according to known experimental data, it is suggested that destructive clustering of nanoparticles is possible in Cu-, Ag-, and Au-ion-implanted dielectric oxide glass media, possessing a strongly negative χ-criterion. Some recent speculations trying to ascribe equally this ability to soft chalcogenide glasses despite an obvious difference in the corresponding bond dissociation energies have been disclosed and criticized as inconclusive.

  9. Temperature and size-dependent Hamaker constants for metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Jiang, K.; Pinchuk, P.

    2016-08-01

    Theoretical values of the Hamaker constant have been calculated for metal nanoparticles using Lifshitz theory. The theory describes the Hamaker constant in terms of the permittivity of the interacting bodies. Metal nanoparticles exhibit an internal size effect that alters the dielectric permittivity of the particle when its size falls below the mean free path of the conducting electrons. This size dependence of the permittivity leads to size-dependence of the Hamaker constant for metal nanoparticles. Additionally, the electron damping and the plasma frequency used to model the permittivity of the particle exhibit temperature-dependence, which lead to temperature dependence of the Hamaker constant. In this work, both the size and temperature dependence for gold, silver, copper, and aluminum nanoparticles is demonstrated. The results of this study might be of interest for studying the colloidal stability of nanoparticles in solution.

  10. A review of the application of anodization for the fabrication of nanotubes on metal implant surfaces.

    PubMed

    Minagar, Sepideh; Berndt, Christopher C; Wang, James; Ivanova, Elena; Wen, Cuie

    2012-08-01

    Metal implants are the best choice for the long-term replacement of hard tissue, such as hip and knee joints, because of their excellent mechanical properties. Titanium and its alloys, due to their self-organized oxide layer, which protects the surface from corrosion and prevents ion release, are widely accepted as biocompatible metal implants. Surface modification is essential for the promotion of the osseointegration of these biomaterials. Nanotubes fabricated on the surface of metal implants by anodization are receiving ever-increasing attention for surface modification. This paper provides an overview of the employment of anodization for nanotubes fabricated on the surface of titanium, titanium alloys and titanium alloying metals such as niobium, tantalum and zirconium metal implants. This work explains anodic oxidation and the manner by which nanotubes form on the surface of the metals. It then assesses this topical research to indicate how changes in anodizing conditions influence nanotube characteristics such as tube diameters and nanotube-layer thickness.

  11. General and programmable synthesis of hybrid liposome/metal nanoparticles

    PubMed Central

    Lee, Jin-Ho; Shin, Yonghee; Lee, Wooju; Whang, Keumrai; Kim, Dongchoul; Lee, Luke P.; Choi, Jeong-Woo; Kang, Taewook

    2016-01-01

    Hybrid liposome/metal nanoparticles are promising candidate materials for biomedical applications. However, the poor selectivity and low yield of the desired hybrid during synthesis pose a challenge. We designed a programmable liposome by selective encoding of a reducing agent, which allows self-crystallization of metal nanoparticles within the liposome to produce stable liposome/metal nanoparticles alone. We synthesized seven types of liposome/monometallic and more complex liposome/bimetallic hybrids. The resulting nanoparticles are tunable in size and metal composition, and their surface plasmon resonance bands are controllable in visible and near infrared. Owing to outer lipid bilayer, our liposome/Au nanoparticle shows better colloidal stability in biologically relevant solutions as well as higher endocytosis efficiency than gold nanoparticles without the liposome. We used this hybrid in intracellular imaging of living cells via surface-enhanced Raman spectroscopy, taking advantage of its improved physicochemical properties. We believe that our method greatly increases the utility of metal nanoparticles in in vivo applications. PMID:28028544

  12. Lattice measurement and alloy compositions in metal and bimetallic nanoparticles.

    PubMed

    Tsen, S-C Y; Crozier, P A; Liu, J

    2003-12-01

    A new reliable method for determining the lattice spacings of metallic and bimetallic nanoparticles in phase contrast high resolution electron microscopy (HREM) images was developed. In this study, we discuss problems in applying HREM techniques to single metal (Pt and Au) and bimetallic (AuPd) nanoparticles of unknown shapes and random orientations. Errors arising from particle tilt and edge effects are discussed and analysis criteria are presented to reduce these errors in measuring the lattice parameters of nanoparticles. The accuracy of an individual particle lattice measurement is limited by an effective standard deviation which depends on the size of the individual nanoparticle. For example, the standard deviation for 20-30 A Pt or Au nanoparticles is about 1.5%. To increase the accuracy in determining the lattice spacings of nanoparticles, statistical methods have to be used to obtain the average lattice spacing of an ensemble of nanoparticles. We measured approximately 100 nanoparticles with sizes in the range of 20-30 A and found that the mean lattice spacing can be determined to within 0.2%. By applying Vegard's law to the AuPd bimetallic systems we successfully detected the presence of alloying. For 30 A nanoparticles, the estimated ultimate error in determining the composition of the AuPd alloy is about 3% provided that at least 100 particles are measured. Finally, the challenges in determining the presence of more than one alloy phases in bimetallic nanoparticle systems were also discussed.

  13. Atomically Precise Colloidal Metal Nanoclusters and Nanoparticles: Fundamentals and Opportunities.

    PubMed

    Jin, Rongchao; Zeng, Chenjie; Zhou, Meng; Chen, Yuxiang

    2016-09-28

    Colloidal nanoparticles are being intensely pursued in current nanoscience research. Nanochemists are often frustrated by the well-known fact that no two nanoparticles are the same, which precludes the deep understanding of many fundamental properties of colloidal nanoparticles in which the total structures (core plus surface) must be known. Therefore, controlling nanoparticles with atomic precision and solving their total structures have long been major dreams for nanochemists. Recently, these goals are partially fulfilled in the case of gold nanoparticles, at least in the ultrasmall size regime (1-3 nm in diameter, often called nanoclusters). This review summarizes the major progress in the field, including the principles that permit atomically precise synthesis, new types of atomic structures, and unique physical and chemical properties of atomically precise nanoparticles, as well as exciting opportunities for nanochemists to understand very fundamental science of colloidal nanoparticles (such as the stability, metal-ligand interfacial bonding, ligand assembly on particle surfaces, aesthetic structural patterns, periodicities, and emergence of the metallic state) and to develop a range of potential applications such as in catalysis, biomedicine, sensing, imaging, optics, and energy conversion. Although most of the research activity currently focuses on thiolate-protected gold nanoclusters, important progress has also been achieved in other ligand-protected gold, silver, and bimetal (or alloy) nanoclusters. All of these types of unique nanoparticles will bring unprecedented opportunities, not only in understanding the fundamental questions of nanoparticles but also in opening up new horizons for scientific studies of nanoparticles.

  14. High current metal ion implantation to synthesize some conducting metal-silicides

    SciTech Connect

    Liu, B. X.; Gao, K. Y.

    1999-06-10

    High current metal-ion implantation by a metal vapor vacuum arc ion source was conducted to synthesize some conducting metal-silicides. It was found that C54-TiSi{sub 2}, ZrSi{sub 2}, NiSi{sub 2}, CoSi{sub 2}, {beta}-FeSi{sub 2}, NbSi{sub 2} and TaSi{sub 2} layers on Si wafers with good electric properties could be obtained directly after implantation. In comparison, the formation of some other silicides like {alpha}-FeSi{sub 2}, NbSi{sub 2}, TaSi{sub 2}, tetragonal-WSi{sub 2} and tetragonal-MoSi{sub 2} required an additional post-annealing to improve their crystallinity and thus their electric properties. Interestingly, the NiSi{sub 2} layers of superior electric properties were obtained at a selected Ni-ion current density of 35 {mu}A/cm{sup 2}. At this current, a beam heating raised the Si wafer to a specific temperature of 380 deg. C, at which the size difference between NiSi{sub 2} and Si lattices was nil. The resistivity of the NiSi{sub 2} layers so obtained was much lower than that of the Ni-disilicide formed by solid-state reaction at >750 deg. C. The formation mechanism of the above metal-silicides and the associated electric properties will also be discussed.

  15. Biogenic synthesis of metallic nanoparticles and prospects toward green chemistry.

    PubMed

    Adil, Syed Farooq; Assal, Mohamed E; Khan, Mujeeb; Al-Warthan, Abdulrahman; Siddiqui, Mohammed Rafiq H; Liz-Marzán, Luis M

    2015-06-07

    The immense importance of nanoparticles and their applications is a strong motivation for exploring new synthetic techniques. However, due to strict regulations that manage the potential environmental impacts greener alternatives for conventional synthesis are the focus of intense research. In the scope of this perspective, a concise discussion about the use of green reducing and stabilizing agents toward the preparation of metal nanoparticles is presented. Reports on the synthesis of noble metal nanoparticles using plant extracts, ascorbic acid and sodium citrate as green reagents are summarized and discussed, pointing toward an urgent need of understanding the mechanistic aspects of the involved reactions.

  16. Synthesis and deposition of metal nanoparticles by gas condensation process

    SciTech Connect

    Maicu, Marina Glöß, Daniel; Frach, Peter; Schmittgens, Ralph; Gerlach, Gerald; Hecker, Dominic

    2014-03-15

    In this work, the synthesis of Pt and Ag nanoparticles by means of the inert gas phase condensation of sputtered atomic vapor is presented. The process parameters (power, sputtering time, and gas flow) were varied in order to study the relationship between deposition conditions and properties of the nanoparticles such as their quantity, size, and size distribution. Moreover, the gas phase condensation process can be combined with a plasma enhanced chemical vapor deposition procedure in order to deposit nanocomposite coatings consisting of metallic nanoparticles embedded in a thin film matrix material. Selected examples of application of the generated nanoparticles and nanocomposites are discussed.

  17. New optical properties of MgO after MeV metal ion implantation

    NASA Astrophysics Data System (ADS)

    Zimmerman, R. L.; Ila, D.; Williams, E. K.; Sarkisov, S. S.; Poker, D. B.; Hensley, D. K.

    1999-06-01

    The implantation of metal ions into single crystals of MgO(100) followed by thermal annealing leads to an increase in absorption of ultra violet and visible light. Metal ions of Au, Sn, Ag, Cu and Ti were implanted at a depth of a few thousand Angstroms followed by thermal annealing. MgO samples implanted with He and Si ions at greater depths were used to study the optical effects and thermal annealing of radiation damage. The influence of bombardment fluence and heat treatment on the size of the metal clusters and on the fraction of atoms in clusters were measured using absorption photospectrometry.

  18. Shape effects on nanoparticle engulfment for metal matrix nanocomposites

    NASA Astrophysics Data System (ADS)

    Ozsoy, Istemi Baris; Li, Gang; Choi, Hongseok; Zhao, Huijuan

    2015-07-01

    Obtaining a uniform dispersion of the nanoparticles and their structural integrity in metal matrix is a prominent obstacle to use the intrinsic properties of metal matrix nanocomposites (MMNCs) to the full extent. In this study, a potential way to overcome the scientific and technical barrier of nanoparticle dispersion in high performance lightweight MMNCs is presented. The goal is to identify the shape and size of Al2O3 nanoparticle for its optimal dispersion in Al matrix. Critical velocity of solidification is calculated numerically for spherical, cylindrical and disk-shaped nanoparticles using an analytical model which incorporates drag force, intermolecular force and inertia effect. The results show that it is possible to reduce the critical solidification velocity for nanoparticle capture by 6 times with proper shape modification.

  19. In Situ Synthesis of Metal Nanoparticle Embedded Hybrid Soft Nanomaterials.

    PubMed

    Divya, Kizhmuri P; Miroshnikov, Mikhail; Dutta, Debjit; Vemula, Praveen Kumar; Ajayan, Pulickel M; John, George

    2016-09-20

    The allure of integrating the tunable properties of soft nanomaterials with the unique optical and electronic properties of metal nanoparticles has led to the development of organic-inorganic hybrid nanomaterials. A promising method for the synthesis of such organic-inorganic hybrid nanomaterials is afforded by the in situ generation of metal nanoparticles within a host organic template. Due to their tunable surface morphology and porosity, soft organic materials such as gels, liquid crystals, and polymers that are derived from various synthetic or natural compounds can act as templates for the synthesis of metal nanoparticles of different shapes and sizes. This method provides stabilization to the metal nanoparticles by the organic soft material and advantageously precludes the use of external reducing or capping agents in many instances. In this Account, we exemplify the green chemistry approach for synthesizing these materials, both in the choice of gelators as soft material frameworks and in the reduction mechanisms that generate the metal nanoparticles. Established herein is the core design principle centered on conceiving multifaceted amphiphilic soft materials that possess the ability to self-assemble and reduce metal ions into nanoparticles. Furthermore, these soft materials stabilize the in situ generated metal nanoparticles and retain their self-assembly ability to generate metal nanoparticle embedded homogeneous organic-inorganic hybrid materials. We discuss a remarkable example of vegetable-based drying oils as host templates for metal ions, resulting in the synthesis of novel hybrid nanomaterials. The synthesis of metal nanoparticles via polymers and self-assembled materials fabricated via cardanol (a bioorganic monomer derived from cashew nut shell liquid) are also explored in this Account. The organic-inorganic hybrid structures were characterized by several techniques such as UV-visible spectroscopy, scanning electron microscopy (SEM), and

  20. Fabrication of Metal Nanoparticles from Fungi and Metal Salts: Scope and Application

    NASA Astrophysics Data System (ADS)

    Siddiqi, Khwaja Salahuddin; Husen, Azamal

    2016-02-01

    Fungi secrete enzymes and proteins as reducing agents which can be used for the synthesis of metal nanoparticles from metal salts. Large-scale production of nanoparticles from diverse fungal strains has great potential since they can be grown even in vitro. In recent years, various approaches have been made to maximize the yield of nanoparticles of varying shape, size, and stability. They have been characterized by thermogravimetric analysis, X-ray diffractometry, SEM/TEM, zeta potential measurements, UV-vis, and Fourier transform infrared (FTIR) spectroscopy. In this review, we focus on the biogenic synthesis of metal nanoparticles by fungi to explore the chemistry of their formation extracellularly and intracellularly. Emphasis has been given to the potential of metal nanoparticles as an antimicrobial agent to inhibit the growth of pathogenic fungi, and on other potential applications.

  1. PIXE microbeam analysis of the metallic debris release around endosseous implants

    NASA Astrophysics Data System (ADS)

    Buso, G. P.; Galassini, S.; Moschini, G.; Passi, P.; Zadro, A.; Uzunov, N. M.; Doyle, B. L.; Rossi, P.; Provencio, P.

    2005-10-01

    The mechanical friction that occurs during the surgical insertion of endosseous implants, both in dentistry and orthopaedics, may cause the detachment of metal debris which are dislodged into the peri-implant tissues and can lead to adverse clinical effects. This phenomenon more likely happens with coated or roughened implants that are the most widely employed. In the present study were studied dental implants screws made of commercially pure titanium and coated using titanium plasma-spray (TPS) technique. The implants were inserted in the tibia of rabbits, and removed "en bloc" with the surrounding bone after one month. After proper processing and mounting on plastic holders, samples from bones were analysed by EDXRF setup at of National Laboratories of Legnaro, INFN, Italy, and consequently at 3 MeV proton microbeam setup at Sandia National Laboratories. Elemental maps were drawn, showing some occasional presence of metal particles in the peri-implant bone.

  2. Optical forces on metallic nanoparticles induced by a photonic nanojet.

    PubMed

    Cui, Xudong; Erni, Daniel; Hafner, Christian

    2008-09-01

    We investigate the optical forces acting on a metallic nanoparticle when the nanoparticle is introduced within a photonic nanojet (PNJ). Optical forces at resonance and off-resonance conditions of the microcylinder or nanoparticle are investigated. Under proper polarization conditions, the whispering gallery mode can be excited in the microcylinder, even at off resonance provided that scattering from the nanoparticle is strong enough. The optical forces are enhanced at resonance either of the single microcylinder or of the nanoparticle with respect to the forces under off-resonant illuminations. We found that the optical forces acting on the nanoparticle depend strongly on the dielectric permittivity of the nanoparticle, as well as on the intensity and the beam width of the PNJ. Hence, metallic sub-wavelength nanoparticle can be efficiently trapped by PNJs. Furthermore, the PNJ's attractive force can be simply changed to a repulsive force by varying the polarization of the incident beam. The changed sign of the force is related to the particle's polarizability and the excitation of localized surface plasmons in the nanoparticle.

  3. Transition metal-substituted cobalt ferrite nanoparticles for biomedical applications.

    PubMed

    Sanpo, Noppakun; Berndt, Christopher C; Wen, Cuie; Wang, James

    2013-03-01

    Transition metals of copper, zinc, chromium and nickel were substituted into cobalt ferrite nanoparticles via a sol-gel route using citric acid as a chelating agent. The microstructure and elemental composition were characterized using scanning electron microscopy combined with energy-dispersive X-ray spectroscopy. Phase analysis of transition metal-substituted cobalt ferrite nanoparticles was performed via X-ray diffraction. Surface wettability was measured using the water contact angle technique. The surface roughness of all nanoparticles was measured using profilometry. Moreover, thermogravimetric analysis and differential scanning calorimetry were performed to determine the temperature at which the decomposition and oxidation of the chelating agents took place. Results indicated that the substitution of transition metals influences strongly the microstructure, crystal structure and antibacterial property of the cobalt ferrite nanoparticles.

  4. Optical absorption enhancement of hybrid-plasmonic-based metal-semiconductor-metal photodetector incorporating metal nanogratings and embedded metal nanoparticles.

    PubMed

    Tan, Chee Leong; Karar, Ayman; Alameh, Kamal; Lee, Yong Tak

    2013-01-28

    We propose and numerically demonstrate a high absorption hybrid-plasmonic-based metal semiconductor metal photodetector (MSM-PD) comprising metal nanogratings, a subwavelength slit and amorphous silicon or germanium embedded metal nanoparticles (NPs). Simulation results show that by optimizing the metal nanograting parameters, the subwavelength slit and the embedded metal NPs, a 1.3 order of magnitude increase in electric field is attained, leading to 28-fold absorption enhancement, in comparison with conventional MSM-PD structures. This is 3.5 times better than the absorption of surface plasmon polariton (SPP) based MSM-PD structures employing metal nanogratings and a subwavelength slit. This absorption enhancement is due to the ability of the embedded metal NPs to enhance their optical absorption and scattering properties through light-stimulated resonance aided by the conduction electrons of the NPs.

  5. Formation of Ge nanoparticles in SiOxNy by ion implantation and thermal annealing

    DOE PAGES

    Mirzaei, Sahar; Kremer, F.; Sprouster, D. J.; ...

    2015-10-20

    Germanium nanoparticles embedded within dielectric matrices hold much promise for applications in optoelectronic and electronic devices. Here we investigate the formation of Ge nanoparticles in amorphous SiO1.67N0.14 as a function of implanted atom concentration and thermal annealing temperature. Using x-ray absorption spectroscopy and other complementary techniques, we show Ge nanoparticles exhibit significant finite-size effects such that the coordination number decreases and structural disorder increases as the nanoparticle size decreases. While the composition of SiO1.67N0.14 is close to that of SiO2, we demonstrate that the addition of this small fraction of N yields a much reduced nanoparticle size relative to thosemore » formed in SiO2 under comparable implantation and annealing conditions. We attribute this difference to an increase in an atomic density and a much reduced diffusivity of Ge in the oxynitride matrix. Finally, these results demonstrate the potential for tailoring Ge nanoparticle sizes and structural properties in the SiOxNy matrices by controlling the oxynitride stoichiometry.« less

  6. Shape-controlled syntheses of metal oxide nanoparticles by the introduction of rare-earth metals.

    PubMed

    Song, Hyo-Won; Kim, Na-Young; Park, Ji-Eun; Ko, Jae-Hyeon; Hickey, Robert J; Kim, Yong-Hyun; Park, So-Jung

    2017-02-23

    Here, we report the size- and shape-controlled synthesis of metal oxide nanoparticles through the introduction of rare-earth metals. The addition of gadolinium oleate in the synthesis of iron oxide nanoparticles induced sphere-to-cube shape changes of nanoparticles and generated iron oxide nanocubes coated with gadolinium. Based on experimental investigations and density functional theory (DFT) calculations, we attribute the shape change to the facet-selective binding of undecomposed gadolinium oleates. While many previous studies on the shape-controlled syntheses of nanoparticles rely on the stabilization of specific crystal facets by anionic surfactants or their decomposition products, this study shows that the interaction between growing transition metal oxide nanoparticles and rare-earth metal complexes can be used as a robust new mechanism for shape-controlled syntheses. Indeed, we demonstrated that this approach was applicable to other transition metal oxide nanoparticles (i.e., manganese oxide and manganese ferrite) and rare earth metals (i.e., gadolinium, europium, and cerium). This study also demonstrates that the nature of metal-ligand bonding can play an important role in the shape control of nanoparticles.

  7. Toxicity of heavy metals and metal-containing nanoparticles on plants.

    PubMed

    Mustafa, Ghazala; Komatsu, Setsuko

    2016-08-01

    Plants are under the continual threat of changing climatic conditions that are associated with various types of abiotic stresses. In particular, heavy metal contamination is a major environmental concern that restricts plant growth. Plants absorb heavy metals along with essential elements from the soil and have evolved different strategies to cope with the accumulation of heavy metals. The use of proteomic techniques is an effective approach to investigate and identify the biological mechanisms and pathways affected by heavy metals and metal-containing nanoparticles. The present review focuses on recent advances and summarizes the results from proteomic studies aimed at understanding the response mechanisms of plants under heavy metal and metal-containing nanoparticle stress. Transport of heavy metal ions is regulated through the cell wall and plasma membrane and then sequestered in the vacuole. In addition, the role of different metal chelators involved in the detoxification and sequestration of heavy metals is critically reviewed, and changes in protein profiles of plants exposed to metal-containing nanoparticles are discussed in detail. Finally, strategies for gaining new insights into plant tolerance mechanisms to heavy metal and metal-containing nanoparticle stress are presented. This article is part of a Special Issue entitled: Plant Proteomics--a bridge between fundamental processes and crop production, edited by Dr. Hans-Peter Mock.

  8. The electrochemical behavior of metallic implant materials as an indicator of their biocompatibility.

    PubMed

    Zitter, H; Plenk, H

    1987-07-01

    This study introduces a simple in vitro arrangement to measure current densities of implant metals. The in vivo condition of a metallic implant lying in tissues exhibiting different redox potentials is simulated in so-called straddle tests by applying a constant potential difference of 250 mV in saline containing the stable, fast-reacting redox system K4Fe(CN)6/K3Fe(CN)6. From a variety of corrosion-resistant implant metals and alloys, gold showed the highest current densities, followed by the stainless steel, the cobalt-based alloy, and the TiAIV-alloy. The pure metals titanium, niobium, and tantalum showed the lowest values. This can be explained by the stable oxide layer on these base metals, preventing an exchange of electrons and thus any redox reaction. This rating of metallic implant materials based on in vitro measurements of current densities is in good accordance with their biocompatibility rating reported from in vivo experiences. It seems that simple and cheap electrochemical tests allow an even more precise differentiation of the suitability of metallic materials for implant purposes than most of the conventional implantation tests, considering that biocompatibility is not only determined by corrosion products, but also by exchange currents and reaction products of redox processes involving tissue compounds.

  9. Enhanced Antimicrobial Activity Of Antibiotics Mixed With Metal Nanoparticles

    NASA Astrophysics Data System (ADS)

    Kumar, Sandeep; Kumar, Neeraj; Bhanjana, Gaurav; Thakur, Rajesh; Dilbaghi, Neeraj

    2011-12-01

    Current producers of antimicrobial technology have a long lasting, environmentally safe, non-leaching, water soluble solution that will eventually replace all poisons and heavy metals. The transition metal ions inevitably exist as metal complexes in biological systems by interaction with the numerous molecules possessing groupings capable of complexation or chelation. Nanoparticles of metal oxides offer a wide variety of potential applications in medicine due to the unprecedented advances in nanobiotechnology research. the bacterial action of antibiotics like penicillin, erythryomycin, ampicillin, streptomycin, kanamycin etc. and that of a mixture of antibiotics and metal and metal oxide nanoparticles like zinc oxide, zirconium, silver and gold on microbes was examined by the agar-well-diffusion method, enumeration of colony-forming units (CFU) and turbidimetry.

  10. Release of Implanted Noble Gases from Metallic Glass Vitreloy During Pyrolysis

    NASA Technical Reports Server (NTRS)

    Meshik, A. P.; Hohenberg, C. M.; Burnett, D. S.; Woolum, D. S.

    2000-01-01

    Vitreloy, a metallic vitreous glass, was examined as a potential target material for the Genesis Mission solar wind collector. Stepped pyrolysis revealed that He and Ne implanted in Vitreloy were efficiently re-trapped during phase transitions.

  11. Manipulation of resonant metallic nanoparticle using 4Pi focusing system.

    PubMed

    Wang, Xiaoyan; Rui, Guanghao; Gong, Liping; Gu, Bing; Cui, Yiping

    2016-10-17

    Metallic nanoparticles have fascinated scientists for over a century and are now heavily utilized in biomedical sciences and engineering. Due to its noncontact and holding nature, optical trapping is suitable to be combined with various applications to manipulate metallic nanoparticles. However, stable trapping of resonant metallic nanoparticles remains challenging due to the strong axial scattering force and severe optical heating effect. In this work, we propose novel optical tweezers constructed around a 4Pi focusing system that is capable of manipulating metallic nanoparticles even under the resonant condition. By properly modulating the spatial distribution of the illumination and adjusting the focusing condition, specific numbers of spherical spots with controllable locations can be generated in the focal region, providing multiple probes to interrogate the sample properties. Besides, stable three-dimensional optical trapping can be formed since the axial scattering force is canceled by the counter-propagating light. The greatly enhanced optical force arising from the extremely high focusing efficiency of the 4Pi focusing system enables to avoid the overheating effect by reducing the input power without destroying the mechanical stability. Moreover, complex motion trajectory of the metallic nanoparticles can be realized via introducing specific phase modulation to the illumination sequentially. The technique demonstrated in this work may open up new avenues for optical manipulation and their applications in various scientific fields.

  12. Metal hybrid nanoparticles for catalytic organic and photochemical transformations.

    PubMed

    Song, Hyunjoon

    2015-03-17

    In order to understand heterogeneous catalytic reactions, model catalysts such as a single crystalline surface have been widely studied for many decades. However, catalytic systems that actually advance the reactions are three-dimensional and commonly have multiple components including active metal nanoparticles and metal oxide supports. On the other hand, as nanochemistry has rapidly been developed and been applied to various fields, many researchers have begun to discuss the impact of nanochemistry on heterogeneous catalysis. Metal hybrid nanoparticles bearing multiple components are structurally very close to the actual catalysts, and their uniform and controllable morphology is suitable for investigating the relationship between the structure and the catalytic properties in detail. In this Account, we introduce four typical structures of metal hybrid nanoparticles that can be used to conduct catalytic organic and photochemical reactions. Metal@silica (or metal oxide) yolk-shell nanoparticles, in which metal cores exist in internal voids surrounded by thin silica (or metal oxide) shells, exhibited extremely high thermal and chemical stability due to the geometrical protection of the silica layers against the metal cores. The morphology of the metal cores and the pore density of the hollow shells were precisely adjusted to optimize the reaction activity and diffusion rates of the reactants. Metal@metal oxide core-shell nanoparticles and inverted structures, where the cores supported the shells serving an active surface, exhibited high activity with no diffusion barriers for the reactants and products. These nanostructures were used as effective catalysts for various organic and gas-phase reactions, including hydrogen transfer, Suzuki coupling, and steam methane reforming. In contrast to the yolk- and core-shell structures, an asymmetric arrangement of distinct domains generated acentric dumbbells and tipped rods. A large domain of each component added multiple

  13. Physicochemical model of detonation synthesis of nanoparticles from metal carboxylates

    NASA Astrophysics Data System (ADS)

    Tolochko, B. P.; Chernyshev, A. P.; Ten, K. A.; Pruuel, E. R.; Zhogin, I. L.; Zubkov, P. I.; Lyakhov, N. Z.; Luk'yanchikov, L. A.; Sheromov, M. A.

    2008-02-01

    We have shown previously that when metal carboxylates are subjected to a shock-wave action, diamond nanoparticles and nanoparticles of metals (Ag, Bi, Co, Fe, Pb) are formed and their characteristic size is about 30-200 Å. The metal nanoparticles formed are covered by an amorphous-carbon layer up to 20 Å thick. In this work we put forward a physicochemical model of the formation of diamond and metal nanoparticles from metal carboxylates upon shock-wave action. The energy released upon detonation inside the precursor is lower than in regions not occupied by the stearates. The characteristic time of temperature equalization has been estimated to be on the order of ˜10-3 s, which is greater by a factor of ˜103 than the characteristic reaction time. Due to the adiabatic nature of the processes occurring, the typical temperature of a "particle" will be lower than the temperature of the surrounding medium. In the framework of the model suggested, it has been assumed that the growth of metal clusters should occur by the diffusion mechanism; i.e., the "building material" is supplied through diffusion. The calculation using our previous experimental data on the reaction time and average size of metal particles has shown that the diffusion properties of the medium in which the metal nanoparticles are formed are close to those of the liquid state of the substance. The temperature and pressure under detonation conditions markedly exceed the analogous parameters characteristic of experiments on the thermodestruction of metal carboxylates. The small time of existence of the reaction mixture is compensated by the high mobility and concentration of reagents.

  14. Spectral dependence of fluorescence near plasmon resonant metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Chen, Yeechi

    The optical properties of fluorophores are significantly modified when placed within the near field (0--100 nm) of plasmon resonant metal nanostructures, due to the competition between increased decay rates and "hotspots" of concentrated electric fields. The decay rates and effective electric field intensities are highly dependent on the relative position of dye and metal and the overlap between plasmon resonance and dye absorption and emission. Understanding these dependencies can greatly improve the performance of biosensing and nanophotonic devices. In this dissertation, the fluorescence intensity of organic dyes and CdSe quantum dots near single metal nanoparticles is studied as a function of the local surface plasmon resonance (LSPR) of the nanoparticle. Single metal nanoparticles have narrow, well-defined, intense local surface plasmon resonances that are tunable across the visible spectrum by changes in size and shape. First, we show that organic dyes can be self-assembled on single silver nanoprisms into known configurations by the hybridization of thiolated DNA oligomers. We correlate the fluorescence intensity of the dyes to the LSPR of the individual nanoprism to which they are attached. For each of three different organic dyes, we observe a strong correlation between the fluorescence intensity of the dye and the degree of spectral overlap with the plasmon resonance of the nanoparticle. On average, we observe the brightest fluorescence from dyes attached to metal nanoparticles that have a LSPR scattering peak 40--120 meV higher in energy than the emission peak of the fluorophore. Second, the plasmon-enhanced fluorescence from CdSe/CdS/CdZnS/ZnS core/shell quantum dots is studied near a variety of silver and gold nanoparticles. With single-particle scattering spectroscopy, the localized surface plasmon resonance spectra of single metal nanoparticles is correlated with the photoluminescence excitation (PLE) spectra of the nearby quantum dots. The PLE

  15. In vitro studies on silver implanted pure iron by metal vapor vacuum arc technique.

    PubMed

    Huang, Tao; Cheng, Yan; Zheng, Yufeng

    2016-06-01

    Pure iron has been verified as a promising biodegradable metal for absorbable cardiovascular stent usage. However, the degradation rate of pure iron is too slow. To accelerate the degradation of the surface of pure iron, silver ions were implanted into pure iron by metal vapor vacuum arc (MEVVA) source at an extracted voltage of 40keV. The implanted influence was up to 2×10(17)ions/cm(2). The composition and depth profiles, corrosion behavior and biocompatibility of Ag ion implanted pure iron were investigated. The implantation depths of Ag was around 60nm. The element Ag existed as Ag2O in the outermost layer, then gradually transited to metal atoms in zero valent state with depth increase. The implantation of Ag ions accelerated the corrosion rate of pure iron matrix, and exhibited much more uniform corrosion behavior. For cytotoxicity assessment, the implantation of Ag ions slightly decreased the viability of all kinds of cell lines used in these tests. The hemolysis rate of Ag ion implanted pure iron was lower than 2%, which was acceptable, whereas the platelet adhesion tests indicated the implantation of Ag ions might increase the risk of thrombosis.

  16. Photothermal effects of plasmonic metal nanoparticles in a fluid

    NASA Astrophysics Data System (ADS)

    Norton, Stephen J.; Vo-Dinh, Tuan

    2016-02-01

    There is a strong interest in the use of plasmonic metal nanoparticles in medical applications involving photothermal therapy. In this study, the problem of calculating the temperature elevation of a fluid arising from the absorption of light by a suspension of plasmonic nanoparticles is examined. The dependence of this temperature increase on the absorption cross section of nanoparticles of different shapes, in particular, nanospheres, nanospheroids, and nanostars, is studied. The nanoparticles behave as point sources of heat production and the time-dependent heat transfer equation is solved assuming that the nanoparticles are confined to a limited region. From this solution, the steady-state temperature of the fluid medium can be calculated and the time constant to achieve this temperature determined.

  17. Incorporation of metal nanoparticles into wood substrate and methods

    SciTech Connect

    Rector, Kirk D; Lucas, Marcel

    2015-11-04

    Metal nanoparticles were incorporated into wood. Ionic liquids were used to expand the wood cell wall structure for nanoparticle incorporation into the cell wall structure. Nanoparticles of elemental gold or silver were found to be effective surface enhanced Raman spectroscopy (SERS) imaging contrast or sensing agents. Nanoparticles of elemental iron were found to be efficient microwave absorbers and caused localized heating for disrupting the integrity of the lignocellulosic matrix. Controls suggest that the localized heating around the iron nanoparticles reduces losses of cellulose in the form of water, volatiles and CO.sub.2. The ionic liquid is needed during the incorporation process at room temperature. The use of small amounts of ionic liquid combined with the absence of an ionic liquid purification step and a lower energy and water use are expected to reduce costs in an up-scaled pretreatment process.

  18. Fluorescent carbon nanoparticles for the fluorescent detection of metal ions.

    PubMed

    Guo, Yongming; Zhang, Lianfeng; Zhang, Shushen; Yang, Yan; Chen, Xihan; Zhang, Mingchao

    2015-01-15

    Fluorescent carbon nanoparticles (F-CNPs) as a new kind of fluorescent nanoparticles, have recently attracted considerable research interest in a wide range of applications due to their low-cost and good biocompatibility. The fluorescent detection of metal ions is one of the most important applications. In this review, we first present the general detection mechanism of F-CNPs for the fluorescent detection of metal ions, including fluorescence turn-off, fluorescence turn-on, fluorescence resonance energy transfer (FRET) and ratiometric response. We then focus on the recent advances of F-CNPs in the fluorescent detection of metal ions, including Hg(2+), Cu(2+), Fe(3+), and other metal ions. Further, we discuss the research trends and future prospects of F-CNPs. We envision that more novel F-CNPs-based nanosensors with more accuracy and robustness will be widely used to assay and remove various metal ions, and there will be more practical applications in coming years.

  19. Biogenic synthesis of metal nanoparticles from actinomycetes: biomedical applications and cytotoxicity.

    PubMed

    Golinska, Patrycja; Wypij, Magdalena; Ingle, Avinash P; Gupta, Indarchand; Dahm, Hanna; Rai, Mahendra

    2014-10-01

    Biogenic synthesis of metal nanoparticles has been well proved by using bacteria, fungi, algae, actinomycetes, plants, etc. Among the different microorganisms used for the synthesis of metal nanoparticles, actinomycetes are less known. Although, there are reports, which have shown that actinomycetes are efficient candidates for the production of metal nanoparticles both intracellularly and extracellularly. The nanoparticles synthesized by the members of actinomycetes present good polydispersity and stability and possess significant biocidal activities against various pathogens. The present review focuses on biological synthesis of metal nanoparticles and their application in medicine. In addition, the toxicity of these biogenic metal nanoparticles to human beings and environment has also been discussed.

  20. Atomic layer deposition to prevent metal transfer from implants: An X-ray fluorescence study

    NASA Astrophysics Data System (ADS)

    Bilo, Fabjola; Borgese, Laura; Prost, Josef; Rauwolf, Mirjam; Turyanskaya, Anna; Wobrauschek, Peter; Kregsamer, Peter; Streli, Christina; Pazzaglia, Ugo; Depero, Laura E.

    2015-12-01

    We show that Atomic Layer Deposition is a suitable coating technique to prevent metal diffusion from medical implants. The metal distribution in animal bone tissue with inserted bare and coated Co-Cr alloys was evaluated by means of micro X-ray fluorescence mapping. In the uncoated implant, the migration of Co and Cr particles from the bare alloy in the biological tissues is observed just after one month and the number of particles significantly increases after two months. In contrast, no metal diffusion was detected in the implant coated with TiO2. Instead, a gradient distribution of the metals was found, from the alloy surface going into the tissue. No significant change was detected after two months of aging. As expected, the thicker is the TiO2 layer, the lower is the metal migration.

  1. Structure Evolution of Metal Nanoparticles in Water Environment

    NASA Astrophysics Data System (ADS)

    Gao, Yi; Zhu, Beien

    Metal nanoparticles have drawn extensive attentions in materials science due to their widespread applications in electronics, engineering and catalysis. A very fundamental question is their structure evolution and surface segregation. Many recent observations have shown that reactive gases or supports may have strong effects on the morphology change and surface segregation. However, the effect of water--the most common solvent and environment--has not received enough attention. Here, we will give two examples to show water adsorption could induce the morphology change and strong surface segregation tendencies for the metal nanoparticles. This finding not only prompts us to re-examine the potential effects of water on metal nanoparticles, but would be also very helpful as a guide for the further theoretical and experimental studies in this field.

  2. Precipitation of heterogeneous nanostructures: Metal nanoparticles and dielectric nanocrystallites

    SciTech Connect

    Masai, Hirokazu; Takahashi, Yoshihiro; Fujiwara, Takumi; Tokuda, Yomei; Yoko, Toshinobu

    2010-07-15

    Heterogeneous precipitation of nanocrystallites of metallic Bi and anatase was observed in CaO-Bi{sub 2}O{sub 3}-B{sub 2}O{sub 3}-Al{sub 2}O{sub 3}-TiO{sub 2} glass-ceramics. Addition of AlN reduced the Bi{sub 2}O{sub 3} to Bi metal nanoparticles, which were uniformly dispersed in the glass. After heat-treatment of the Bi-precipitated glass around the glass transition temperature, nanocrystalline anatase precipitated out without aggregation of the Bi metal particles. It was found that the anatase nanocrystal size was affected by the distance between a nanocrystal and a precipitated Bi nanoparticle. The glass-ceramic produced is a functional material containing a random dispersion of different types of nanoparticles with different dielectric constants.

  3. Manipulation of metallic nanoparticle with evanescent vortex Bessel beam.

    PubMed

    Rui, Guanghao; Wang, Xiaoyan; Cui, Yiping

    2015-10-05

    In this work, we propose a novel strategy to optically trap and manipulate metallic nanoparticles using evanescent vortex Bessel beam (EVBB). A versatile method is presented to generate evanescent Bessel beam with tunable optical angular momentum by focusing a radially polarized vortex beam onto a one-dimensional photonics band gap structure. The behavior of a metallic nanoparticle in the EVBB is numerically studied. We show that such particle can be stably trapped near the surface. The orbital angular momentum drives the metallic nanoparticle to orbit around the beam axis, and the direction of the orbital motion is controlled by the handedness of the helical phase front. The technique demonstrated in this work may open up new avenues for optical manipulation, and the non-contact tunable orbiting dynamics of the trapped particle may find important applications in higher resolution imaging techniques.

  4. Optical studies of ion-beam synthesized metal alloy nanoparticles

    NASA Astrophysics Data System (ADS)

    Magudapathy, P.; Srivatsava, S. K.; Gangopadhyay, P.; Amirthapandian, S.; Sairam, T. N.; Panigrahi, B. K.

    2015-06-01

    AuxAg1-x alloy nanoparticles with tunable surface plasmon resonance (SPR) have been synthesized on a silica glass substrate. A small Au foil on an Ag foil is irradiated as target substrates such that ion beam falls on both Ag foil and Au foils. Silica slides are kept at an angle ˜45° with respect to the metallic foils. While irradiating the metallic foils with 100 keV Ar+ ions, sputtered Au and Ag atoms get deposited on the silica-glass. In this configuration the foils have been irradiated by Ar+ ions to various fluences at room temperature and the sputtered species are collected on silica slides. Formation of AuxAg1-x nanoparticles has been confirmed from the optical absorption measurements. With respect to the exposure area of Au and Ag foils to the ion beam, the SPR peak position varies from 450 to 500 nm. Green photoluminescence has been observed from these alloy metal nanoparticles.

  5. Insights on Metal Based Dental Implants and their Interaction with the Surrounding Tissues.

    PubMed

    Popa, Marcela; Hussien, Mohamed D; Cirstea, Alexandra; Grigore, Raluca; Lazar, Veronica; Bezirtzoglou, Eugenia; Chifiriuc, Mariana Carmen; Sakizlian, Monica; Stavropoulou, Elisavet; Bertesteanu, Serban

    2015-01-01

    At present, the use of dental implants is a very common practice as tooth loss is a frequent problem and can occur as a result of disease or trauma. An implant is usually made of biocompatible materials that do not cause rejection reactions and allow the implant union with the respective bone. To achieve this goal, the implant surface may have different structures and coatings, generally used to increase the adherence of the implant to the bone and to decrease the risk of the periimplantar inflammatory reactions. This review gives some insights of the metal based materials used for dental implants, their limits, improvement strategies as well as the pathophysiology, diagnosis, treatment and prevention of periimplantary diseases.

  6. A Method of Producing Surface Conduction on Ceramic Accelerator Components Using Metal Ion Implantation

    SciTech Connect

    Liu, F.; Brown, I.; Phillips, H.; Biallas, George; Siggins, Timothy

    1997-05-01

    An important technique used for the suppression of surface flashover on high voltage DC ceramic insulators as well as for RF windows is that of providing some surface conduction to bleed off accumulated surface charge. We have used metal ion implantation to modify the surface of high voltage ceramic vacuum insulators to provide a niform surface resistivity of approximately 5 x 1010 W/square. A vacuum arc ion source based implanter was used to implant Pt at an energy of about 135 keV to doses of up to more than 5 x 1016 ions/cm2 into small ceramic test coupons and also into the inside surface of several ceramic accelerator columns 25 cm I. D. by 28 cm long. Here we describe the experimental set-up used to do the ion implantation and summarize the results of our exploratory work on implantation into test coupons as well as the implantations of the actual ceramic columns.

  7. Silver-copper alloy nanoparticles for metal enhanced luminescence

    NASA Astrophysics Data System (ADS)

    Chowdhury, Sanchari; Bhethanabotla, Venkat R.; Sen, Rajan

    2009-09-01

    Large metal enhanced luminescence was realized at the vicinity of easily fabricated Ag-Cu alloy nanoparticles upon tuning of their surface plasmon resonance spectra by changing only one experimental variable—the annealing temperature, for maximum spectral overlap with the emission and excitation spectra of the luminophores. We observed strong emission enhancement of luminophores (141.48±19.20 times for Alexa Fluor 488 and 23.91±12.37 times for Alexa Fluor 594) at the vicinity of these Ag-Cu nanoparticles, which is significantly larger than for pure Ag nanoparticles. We present theoretical calculations to provide insights into these experimental findings.

  8. HRTEM and XPS study of nanoparticle formation in Zn{sup +} ion implanted Si

    SciTech Connect

    Privezentsev, Vladimir V.; Tabachkova, Natalya Yu.; Lebedinskii, Yurii Yu.

    2014-02-21

    The results of investigations of nanoparticles (NPs) formation in a near surface layer of Si substrate after {sup 64}Zn{sup +} ion implantation and thermal annealing are presented. The implantation energy and dose were correspondently E=100keV and D = 2×10{sup 16} cm{sup −2}. Than the samples were subsequently isochronously subjected to furnace annealing during 1h in neutral atmosphere at 400°C and in oxygen atmosphere at 600, 700 and 800°C. The visualization of near surface layer was carried out by transmission electron microscopy with addition of electron diffraction. The energy dispersive spectroscopy was used for value of impurity concentration. The charge state of implanted zinc, silicon matrix atom and oxygen and were carried out by X-ray photoelectron spectroscopy and Auger electron spectroscopy.

  9. Removal of Metal Nanoparticles Colloidal Solutions by Water Plants

    NASA Astrophysics Data System (ADS)

    Olkhovych, Olga; Svietlova, Nataliia; Konotop, Yevheniia; Karaushu, Olena; Hrechishkina, Svitlana

    2016-11-01

    The ability of seven species of aquatic plants ( Elodea canadensis, Najas guadelupensis, Vallisneria spiralis L., Riccia fluitans L., Limnobium laevigatum, Pistia stratiotes L., and Salvinia natans L.) to absorb metal nanoparticles from colloidal solutions was studied. It was established that investigated aquatic plants have a high capacity for removal of metal nanoparticles from aqueous solution (30-100%) which indicates their high phytoremediation potential. Analysis of the water samples content for elements including the mixture of colloidal solutions of metal nanoparticles (Mn, Cu, Zn, Ag + Ag2O) before and after exposure to plants showed no significant differences when using submerged or free-floating hydrophytes so-called pleuston. However, it was found that the presence of submerged hydrophytes in aqueous medium ( E. canadensis, N. guadelupensis, V. spiralis L., and R. fluitans L.) and significant changes in the content of photosynthetic pigments, unlike free-floating hydrophytes ( L. laevigatum, P. stratiotes L., S. natans L.), had occur. Pleuston possesses higher potential for phytoremediation of contaminated water basins polluted by metal nanoparticles. In terms of removal of nanoparticles among studied free-floating hydrophytes, P. stratiotes L. and S. natans L. deserve on special attention.

  10. Laser fabrication of 2D and 3D metal nanoparticle structures and arrays.

    PubMed

    Kuznetsov, A I; Kiyan, R; Chichkov, B N

    2010-09-27

    A novel method for fabrication of 2D and 3D metal nanoparticle structures and arrays is proposed. This technique is based on laser-induced transfer of molten metal nanodroplets from thin metal films. Metal nanoparticles are produced by solidification of these nanodroplets. The size of the transferred nanoparticles can be controllably changed in the range from 180 nm to 1500 nm. Several examples of complex 2D and 3D microstructures generated form gold nanoparticles are demonstrated.

  11. Confined Growth of Metal Nanoparticles Within 3D DNA Origami Molds.

    PubMed

    Sun, Wei; Shen, Jie

    2017-01-01

    Manufacturing prescribed shaped metal nanoparticles promises emerging applications in plasmonics, energy, and disease diagnosis. The key to the shape-controllable synthesis is generating local environments encoded with prescribed geometrical information. Here, we describe a general strategy that uses 3D self-assembled DNA origami as mold to confine the casting growth of metal nanoparticle. By transferring the shape information from DNA cavities to metal nanoparticles, metal nanoparticles with prescribed shapes, dimensions, and surface binding features could be rationally designed and synthesized.

  12. Nonlinear optical susceptibilities of semiconductor quantum dot - metal nanoparticle hybrids

    NASA Astrophysics Data System (ADS)

    Terzis, A. F.; Kosionis, S. G.; Boviatsis, J.; Paspalakis, E.

    2016-03-01

    We theoretically study nonlinear optical effects of a semiconductor quantum dot and a spherical metal nanoparticle coupled via long-range Coulomb interaction. We solve the relevant density matrix equations in steady state and use proper perturbation theory to obtain closed-form analytical expressions for the nonlinear susceptibilities of the quantum dot, the metal nanoparticle, and the entire coupled system, up to fifth order. We also investigate the influence of the material of the semiconductor and the impact of the interparticle distance on the form of the spectra of the nonlinear susceptibilities.

  13. Radiation damping in metal nanoparticle pairs.

    PubMed

    Dahmen, Christian; Schmidt, Benjamin; von Plessen, Gero

    2007-02-01

    The radiation damping rate of plasmon resonances in pairs of spherical gold nanoparticles is calculated. The radiative line width of the plasmon resonance indicates significant far-field coupling between the nanoparticles over distances many times the particle diameter. The radiation damping of the coupled particle-plasmon mode alternates between superradiant and subradiant behavior when the particle spacing is varied. At small particle spacings where near-field coupling occurs, the radiation damping rate lies far below that of an isolated particle.

  14. The electrochemisty of surface modified <10 nm metal oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Roberts, Joseph J. P.

    Chapter One provides a general introduction of the research on metal oxide nanoparticles (MOx), highlighting their synthesis, surface modification, and functionalization. Emphasis is given to the different synthetic route for producing small (<10 nm) MOx nanoparticles with narrow size distributions. Different methods for modifying their surface with small organic molecules are discussed with focus given to silanes and phosphates. Furthermore, functionalizing surface modified nanoparticles for specific functions is addressed, with markers for analytically relevant nanoscale quantification being the primary focus. Chapter Two describes in detail the thermal degradation synthesis used for the generation of small MOx nanoparticles. It demonstrates the versatile of the synthesis by successfully synthesizing ZrO 2 and IrO2 nanoparticles. Preliminary work involving the formation of Bi2S3, Bi2O3, and RuO2 nanomaterials is also addressed. The solvothermal synthesis of indium tin oxide (ITO) is also shown for comparison to ITO produced by thermal degradation. Chapter Three details the surface modification of ITO nanoparticles and subsequent electrochemical tagging with a ferrocene moiety. ITO nanoparticles were synthesized via thermal degradation. These nanoparticles underwent a ligand exchange with a covalently binding mondentate silane terminated with a primary amine. Acyl chloride coupling between the amine and chlorocarbonylferrocene provided an electrochemical tag to quantify the level of surface modification. Electrochemisty of the quasi-diffusing nanoparticles was evaluated via cyclic voltammetry (CV), chronoamperometry (CA), and mircodisk electrode (microE) experiments. Chapter Four investigates spectroscopic tagging of ITO and ZrO2 nanoparticles as well as electrochemical tagging of ZrO 2 and IrO2 nanoparticles. An unbound azo-dye was synthesized and attempts were made to attach the dye to the surface of ITO nanoparticles. Imine couple between a spectroscopic tag

  15. No association between serum metal ions and implant fixation in large-head metal-on-metal total hip arthroplasty

    PubMed Central

    Søballe, Kjeld; Jakobsen, Stig Storgaard; Lorenzen, Nina Dyrberg; Mechlenburg, Inger; Stilling, Maiken

    2014-01-01

    Background The mechanism of failure of metal-on-metal (MoM) total hip arthroplasty (THA) has been related to a high rate of metal wear debris, which is partly generated from the head-trunnion interface. However, it is not known whether implant fixation is affected by metal wear debris. Patients and methods 49 cases of MoM THA in 41 patients (10 women) with a mean age of 52 (28–68) years were followed with stereoradiographs after surgery and at 1, 2, and 5 years to analyze implant migration by radiostereometric analysis (RSA). Patients also participated in a 5- to 7-year follow-up with measurement of serum metal ions, questionnaires (Oxford hip score (OHS) and Harris hip score (HHS)), and measurement of cup and stem positions and systemic bone mineral density. Results At 1–2 years, mean total translation (TT) was 0.04 mm (95% CI: –0.07 to 0.14; p = 0.5) for the stems; at 2–5 years, mean TT was 0.13 mm (95% CI: –0.25 to –0.01; p = 0.03), but within the precision limit of the method. For the cups, there was no statistically significant TT or total rotation (TR) at 1–2 and 2–5 years. At 2–5 years, we found 4 cups and 5 stems with TT migrations exceeding the precision limit of the method. There was an association between cup migration and total OHS < 40 (4 patients, 4 hips; p = 0.04), but there were no statistically significant associations between cup or stem migration and T-scores < –1 (n = 10), cup and stem positions, or elevated serum metal ion levels (> 7µg/L (4 patients, 6 hips)). Interpretation Most cups and stems were well-fixed at 1–5 years. However, at 2–5 years, 4 cups and 5 stems had TT migrations above the precision limits, but these patients had serum metal ion levels similar to those of patients without measurable migrations, and they were pain-free. Patients with serum metal ion levels > 7 µg/L had migrations similar to those in patients with serum metal ion levels < 7 µg/L. Metal wear debris does not appear to influence the

  16. Metal nanoparticles in the presence of lipopolysaccharides trigger the onset of metal allergy in mice

    NASA Astrophysics Data System (ADS)

    Hirai, Toshiro; Yoshioka, Yasuo; Izumi, Natsumi; Ichihashi, Ko-Ichi; Handa, Takayuki; Nishijima, Nobuo; Uemura, Eiichiro; Sagami, Ko-Ichi; Takahashi, Hideki; Yamaguchi, Manami; Nagano, Kazuya; Mukai, Yohei; Kamada, Haruhiko; Tsunoda, Shin-Ichi; Ishii, Ken J.; Higashisaka, Kazuma; Tsutsumi, Yasuo

    2016-09-01

    Many people suffer from metal allergy, and the recently demonstrated presence of naturally occurring metal nanoparticles in our environment could present a new candidate for inducing metal allergy. Here, we show that mice pretreated with silver nanoparticles (nAg) and lipopolysaccharides, but not with the silver ions that are thought to cause allergies, developed allergic inflammation in response to the silver. nAg-induced acquired immune responses depended on CD4+ T cells and elicited IL-17A-mediated inflammation, similar to that observed in human metal allergy. Nickel nanoparticles also caused sensitization in the mice, whereas gold and silica nanoparticles, which are minimally ionizable, did not. Quantitative analysis of the silver distribution suggested that small nAg (≤10 nm) transferred to the draining lymph node and released ions more readily than large nAg (>10 nm). These results suggest that metal nanoparticles served as ion carriers to enable metal sensitization. Our data demonstrate a potentially new trigger for metal allergy.

  17. Noble Metal Nanoparticle-loaded Mesoporous Oxide Microspheres for Catalysis

    NASA Astrophysics Data System (ADS)

    Jin, Zhao

    Noble metal nanoparticles/nanocrystals have attracted much attention as catalysts due to their unique characteristics, including high surface areas and well-controlled facets, which are not often possessed by their bulk counterparts. To avoid the loss of their catalytic activities brought about by their size and shape changes during catalytic reactions, noble metal nanoparticles/nanocrystals are usually dispersed and supported finely on solid oxide supports to prevent agglomeration, nanoparticle growth, and therefore the decrease in the total surface area. Moreover, metal oxide supports can also play important roles in catalytic reactions through the synergistic interactions with loaded metal nanoparticles/nanocrystals. In this thesis, I use ultrasonic aerosol spray to produce hybrid microspheres that are composed of noble metal nanoparticles/nanocrystals embedded in mesoporous metal oxide matrices. The mesoporous metal oxide structure allows for the fast diffusion of reactants and products as well as confining and supporting noble metal nanoparticles. I will first describe my studies on noble metal-loaded mesoporous oxide microspheres as catalysts. Three types of noble metals (Au, Pt, Pd) and three types of metal oxide substrates (TiO2, ZrO2, Al 2O3) were selected, because they are widely used for practical catalytic applications involved in environmental cleaning, pollution control, petrochemical, and pharmaceutical syntheses. By considering every possible combination of the noble metals and oxide substrates, nine types of catalyst samples were produced. I characterized the structures of these catalysts, including their sizes, morphologies, crystallinity, and porosities, and their catalytic performances by using a representative reduction reaction from nitrobenzene to aminobenzene. Comparison of the catalytic results reveals the effects of the different noble metals, their incorporation amounts, and oxide substrates on the catalytic abilities. For this particular

  18. Determination of the size distribution of metallic nanoparticles by optical extinction spectroscopy

    SciTech Connect

    Pena, Ovidio; Rodriguez-Fernandez, Luis; Rodriguez-Iglesias, Vladimir; Kellermann, Guinther; Crespo-Sosa, Alejandro; Cheang-Wong, Juan Carlos; Silva-Pereyra, Hector Gabriel; Arenas-Alatorre, Jesus; Oliver, Alicia

    2009-01-20

    A method is proposed to estimate the size distribution of nearly spherical metallic nanoparticles (NPs) from optical extinction spectroscopy (OES) measurements based on Mie's theory and an optimization algorithm. The described method is compared against two of the most widely used techniques for the task: transmission electron microscopy (TEM) and small-angle x-ray scattering (SAXS). The size distribution of Au and Cu NPs, obtained by ion implantation in silica and a subsequent thermal annealing in air, was determined by TEM, grazing-incidence SAXS (GISAXS) geometry, and our method, and the average radius obtained by all the three techniques was almost the same for the two studied metals. Concerning the radius dispersion (RD), OES and GISAXS give very similar results, while TEM considerably underestimates the RD of the distribution.

  19. Absorption properties of metal-semiconductor hybrid nanoparticles.

    PubMed

    Shaviv, Ehud; Schubert, Olaf; Alves-Santos, Marcelo; Goldoni, Guido; Di Felice, Rosa; Vallée, Fabrice; Del Fatti, Natalia; Banin, Uri; Sönnichsen, Carsten

    2011-06-28

    The optical response of hybrid metal-semiconductor nanoparticles exhibits different behaviors due to the proximity between the disparate materials. For some hybrid systems, such as CdS-Au matchstick-shaped hybrids, the particles essentially retain the optical properties of their original components, with minor changes. Other systems, such as CdSe-Au dumbbell-shaped nanoparticles, exhibit significant change in the optical properties due to strong coupling between the two materials. Here, we study the absorption of these hybrids by comparing experimental results with simulations using the discrete dipole approximation method (DDA) employing dielectric functions of the bare components as inputs. For CdS-Au nanoparticles, the DDA simulation provides insights on the gold tip shape and its interface with the semiconductor, information that is difficult to acquire by experimental means alone. Furthermore, the qualitative agreement between DDA simulations and experimental data for CdS-Au implies that most effects influencing the absorption of this hybrid system are well described by local dielectric functions obtained separately for bare gold and CdS nanoparticles. For dumbbell shaped CdSe-Au, we find a shortcoming of the electrodynamic model, as it does not predict the "washing out" of the optical features of the semiconductor and the metal observed experimentally. The difference between experiment and theory is ascribed to strong interaction of the metal and semiconductor excitations, which spectrally overlap in the CdSe case. The present study exemplifies the employment of theoretical approaches used to describe the optical properties of semiconductors and metal nanoparticles, to achieve better understanding of the behavior of metal-semiconductor hybrid nanoparticles.

  20. Battlefield-Acquired Immunogenicity to Metals Affects Orthopaedic Implant Outcome

    DTIC Science & Technology

    2016-12-01

    indicated for subacute removal when they are located near or within a joint, in weight bearing areas, or in proximity to neurovascular structures...and Cr) had metal-on-metal bearing surfaces. In the past these elevated metal ion concentrations demonstrated a positive correlation with...associated with metal-on-metal bearings : A local effect of metal hypersensitivity? J Bone Joint Surg Am 2006 Jun;88(6):1171-2. (5) Ren W, Wu B, Peng

  1. The role of metal nanoparticles and nanonetworks in alloy degradation.

    PubMed

    Zeng, Z; Natesan, K; Cai, Z; Darling, S B

    2008-08-01

    Oxide scale, which is essential to protect structural alloys from high-temperature degradation such as oxidation, carburization and metal dusting, is usually considered to consist simply of oxide phases. Here, we report on a nanobeam X-ray and magnetic force microscopy investigation that reveals that the oxide scale actually consists of a mixture of oxide materials and metal nanoparticles. The metal nanoparticles self-assemble into nanonetworks, forming continuous channels for carbon transport through the oxide scales. To avoid the formation of these metallic particles in the oxide scale, alloys must develop a scale without spinel phase. We have designed a novel alloy that has been tested in a high-carbon-activity environment. Our results show that the incubation time for carbon transport through the oxide scale of the new alloy is more than an order of magnitude longer compared with commercial alloys with similar chromium content.

  2. Industrial applications of ion implantation into metal surfaces

    SciTech Connect

    Williams, J.M.

    1987-07-01

    The modern materials processing technique, ion implantation, has intriguing and attractive features that stimulate the imaginations of scientists and technologists. Success of the technique for introducing dopants into semiconductors has resulted in a stable and growing infrastructure of capital equipment and skills for use of the technique in the economy. Attention has turned to possible use of ion implantation for modification of nearly all surface related properties of materials - optical, chemical and corrosive, tribological, and several others. This presentation provides an introduction to fundamental aspects of equipment, technique, and materials science of ion implantation. Practical and economic factors pertaining to the technology are discussed. Applications and potential applications are surveyed. There are already available a number of ion-implanted products, including ball-and-roller bearings and races, punches-and-dies, injection screws for plastics molding, etc., of potential interest to the machine tool industry.

  3. Use of Metallic Endosseous Implants as a Tooth Substitute.

    DTIC Science & Technology

    1979-06-01

    exposed in the oral cavity and placed in function with the opposing dentition iBACKGROUND The development of a dental implant that will serve as a...single tooth replacement. MATERIALS AND METHODS: HUMAN STUDY (SINGLE TOOTH REPLACEMENT) Volunteer patients were selected who had a full dentition ...the crown was cemented to the implant and placed in function with the opposing dentition . All crowns were cerauco crowns (porcelain fused to gold). The

  4. Low-temperature metallic alloying of copper and silver nanoparticles with gold nanoparticles through digestive ripening.

    PubMed

    Smetana, Alexander B; Klabunde, Kenneth J; Sorensen, Christopher M; Ponce, Audaldo A; Mwale, Benny

    2006-02-09

    We describe a remarkable and simple alloying procedure in which noble metal intermetallic nanoparticles are produced in gram quantities via digestive ripening. This process involves mixing of separately prepared colloids of pure Au and pure Ag or Cu particles and then heating in the presence of an alkanethiol under reflux. The result after 1 h is alloy nanoparticles. Particles synthesized according to this procedure were characterized by UV-vis spectroscopy, EDX analysis, and high-resolution electron microscopy, the results of which confirm the formation of alloy particles. The particles of 5.6+/-0.5 nm diameter for Au/Ag and 4.8+/-1.0 nm diameter for Cu/Au undergo facile self-assembly to form 3-D superlattice ordering. It appears that during this digestive ripening process, the organic ligands display an extraordinary chemistry in which atom transfer between atomically pure copper, silver, and gold metal nanoparticles yields monodisperse alloy nanoparticles.

  5. Oscillatory characteristics of metallic nanoparticles inside lipid nanotubes

    NASA Astrophysics Data System (ADS)

    Sadeghi, Fatemeh; Ansari, Reza; Darvizeh, Mansour

    2015-12-01

    This study is concerned with the oscillatory behavior of metallic nanoparticles, and in particular silver and gold nanoparticles, inside lipid nanotubes (LNTs) using the continuum approximation along with the 6-12 Lennard-Jones (LJ) potential function. The nanoparticle is modeled as a dense sphere and the LNT is assumed to be comprised of six layers including two head groups, two intermediate layers and two tail groups. To evaluate van der Waals (vdW) interactions, analytical expressions are first derived through undertaking surface and volume integrals which are then validated by a fully numerical scheme based on the differential quadrature (DQ) technique. Using the actual force distribution between the two interacting molecules, the equation of motion is directly solved utilizing the Runge-Kutta numerical integration scheme to arrive at the time history of displacement and velocity of the inner core. Also, a semi-analytical expression incorporating both geometrical parameters and initial conditions is introduced for the precise evaluation of oscillation frequency. A comprehensive study is conducted to gain an insight into the influences of nanoparticle radius, LNT length, head and tail group thicknesses and initial conditions on the oscillatory behavior of the metallic nanoparticles inside LNTs. It is found that the escape velocity and oscillation frequency of silver nanoparticles are higher than those of gold ones. It is further shown that the oscillation frequency is less affected by the tail group thickness when compared to the head group thickness.

  6. Improving proton therapy by metal-containing nanoparticles: nanoscale insights

    PubMed Central

    Schlathölter, Thomas; Eustache, Pierre; Porcel, Erika; Salado, Daniela; Stefancikova, Lenka; Tillement, Olivier; Lux, Francois; Mowat, Pierre; Biegun, Aleksandra K; van Goethem, Marc-Jan; Remita, Hynd; Lacombe, Sandrine

    2016-01-01

    The use of nanoparticles to enhance the effect of radiation-based cancer treatments is a growing field of study and recently, even nanoparticle-induced improvement of proton therapy performance has been investigated. Aiming at a clinical implementation of this approach, it is essential to characterize the mechanisms underlying the synergistic effects of nanoparticles combined with proton irradiation. In this study, we investigated the effect of platinum- and gadolinium-based nanoparticles on the nanoscale damage induced by a proton beam of therapeutically relevant energy (150 MeV) using plasmid DNA molecular probe. Two conditions of irradiation (0.44 and 3.6 keV/μm) were considered to mimic the beam properties at the entrance and at the end of the proton track. We demonstrate that the two metal-containing nanoparticles amplify, in particular, the induction of nanosize damages (>2 nm) which are most lethal for cells. More importantly, this effect is even more pronounced at the end of the proton track. This work gives a new insight into the underlying mechanisms on the nanoscale and indicates that the addition of metal-based nanoparticles is a promising strategy not only to increase the cell killing action of fast protons, but also to improve tumor targeting. PMID:27143877

  7. Resonance energy transfer: Dye to metal nanoparticles

    SciTech Connect

    Wari, M. N.; Pujar, G. H.; Inamdar, S. R.

    2015-06-24

    In the present study, surface energy transfer (SET) from Coumarin 540A (C540 A) to Gold nanoparticle (Au) is demonstrated. The observed results show pronounced effect on the photoluminescence intensity and shortening of the lifetime of Coumarin 540A upon interaction with the spherical gold nanoparticle, also there are measured effects on radiative rate of the dye. Experimental results are analyzed with fluorescence resonance energy transfer (FRET) and SET theories. The results obtained from distance-dependent quenching provide experimental evidence that the efficiency curve slope and distance of quenching is best modeled by surface energy transfer process.

  8. A preliminary biomechanical study of a novel carbon-fibre hip implant versus standard metallic hip implants.

    PubMed

    Bougherara, Habiba; Zdero, Rad; Dubov, Anton; Shah, Suraj; Khurshid, Shaheen; Schemitsch, Emil H

    2011-01-01

    Total hip arthroplasty is a widespread surgical approach for treating severe osteoarthritis of the human hip. Aseptic loosening of standard metallic hip implants due to stress shielding and bone loss has motivated the development of new materials for hip prostheses. Numerically, a three-dimensional finite element (FE) model that mimicked hip implants was used to compare a new hip stem to two commercially available implants. The hip implants simulated were a novel CF/PA12 carbon-fibre polyamide-based composite hip stem, the Exeter hip stem (Stryker, Mahwah, NJ, USA), and the Omnifit Eon (Stryker, Mahwah, NJ, USA). A virtual axial load of 3 kN was applied to the FE model. Strain and stress distributions were computed. Experimentally, the three hip stems had their distal portions rigidly mounted and had strain gauges placed along the surface at 3 medial and 3 lateral locations. Axial loads of 3 kN were applied. Measurements of axial stiffness and strain were taken and compared to FE analysis. The overall linear correlation between FE model versus experimental strains showed reasonable results for the lines-of-best-fit for the Composite (Pearson R(2)=0.69, slope=0.82), Exeter (Pearson R(2)=0.78, slope=0.59), and Omnifit (Pearson R(2)=0.66, slope=0.45), with some divergence for the most distal strain locations. From FE analysis, the von Mises stress range for the Composite stem was much lower than that in the Omnifit and Exeter implants by 200% and 45%, respectively. The preliminary experiments showed that the Composite stem stiffness (1982 N/mm) was lower than the metallic hip stem stiffnesses (Exeter, 2460 N/mm; Omnifit, 2543 N/mm). This is the first assessment of stress, strain, and stiffness of the CF/PA12 carbon-fibre hip stem compared to standard commercially-available devices.

  9. [Phytotoxicity of colloidal solutions of metal-containing nanoparticles].

    PubMed

    Konotop, Ie O; Kovalenko, M S; Ulynets', V Z; Meleshko, A O; Batsmanova, L M; Taran, N Iu

    2014-01-01

    Phytotoxicity of colloidal solutions of metal-containing nanoparticles (Ag, Cu, Fe, Zn, Mn) has been investigated using a standard Allium cepa (L.) test system. Toxicity of experimental solutions at the organism level was evaluated in terms of biomass growth of onion roots, and cytotoxicity was estimated by the mitotic index of root meristem cells. The colloidal solutions of metal nanoparticles inhibited the growth of Allium cepa (L.) roots due to their ability to penetrate into cells and interact with their components, and thus to inhibit mitosis. According to our results cytotoxicity of test solutions decreases in the following order: Cu > or = Zn > Ag > or = Fe. Solution of Mn-containing nanoparticles revealed physiological activity according to root growth reaction.

  10. Clinical usefulness of blood metal measurements to assess the failure of metal-on-metal hip implants

    PubMed Central

    Sampson, Barry; Hart, Alister

    2012-01-01

    In April 2010, a Medicines and Healthcare Products Regulatory Agency safety alert concerning all metal-on-metal (MOM) hip replacements recommended measuring chromium and cobalt concentrations when managing patients with painful prostheses. The need for this review is illustrated by the recent surge in requests for these blood tests from orthopaedic surgeons following this alert. The aim is to provide guidance to laboratories in assessing these requests and advising clinicians on interpretation. First, we summarize the basic terminology regarding the types of hip replacements, with emphasis on the MOM type. Second, we describe the clinical concerns over implant-derived wear debris in the local tissues and distant sites. Analytical aspects of the measurement of the relevant metal ions and what factors affect the levels measured are discussed. The application of inductively coupled plasma mass spectrometry techniques to the measurement of these metals is considered in detail. The biological effects of metal wear products are summarized with local toxicity and systemic biological effects considered, including carcinogenicity, genotoxicity and systemic toxicity. Clinical cases are used to illustrate pertinent points. PMID:22155921

  11. Alloying of metal nanoparticles by ion-beam induced sputtering

    NASA Astrophysics Data System (ADS)

    Magudapathy, P.; Srivastava, S. K.; Gangopadhyay, P.; Amirthapandian, S.; Saravanan, K.; Das, A.; Panigrahi, B. K.

    2017-01-01

    Ion-beam sputtering technique has been utilized for controlled synthesis of metal alloy nanoparticles of compositions that can be tuned. Analysis of various experimental results reveals the formation of Ag-Cu alloy nanoparticles on a silica substrate. Surface-plasmon optical resonance positions and observed shifts of Ag Bragg angles in X-ray diffraction pattern particularly confirm formation of alloy nanoparticles on glass samples. Sputtering induced nano-alloying mechanism has been discussed and compared with thermal mixing of Ag and Cu thin films on glass substrates. Compositions and sizes of alloy nanoparticles formed during ion-beam induced sputtering are found to exceed far from the values of thermal mixing.

  12. Structure of reverse microemulsion-templated metal hexacyanoferrate nanoparticles

    PubMed Central

    2012-01-01

    The droplet phase of a reverse microemulsion formed by the surfactant cetyltrimethylammonium ferrocyanide was used as a matrix to synthesize nanoparticles of nickel hexacyanoferrate by adding just a solution of NiCl2 to the microemulsion media. Dynamic light scattering and small-angle neutron scattering measurements show that the reverse microemulsion droplets employed have a globular structure, with sizes that depend on water content. Transmission electron microscopy and electron diffraction are used to obtain information about the structure of the synthesized nanoparticles. The results show that the size and shape of the coordination compound nanoparticles correspond with the size and shape of the droplets, suggesting that the presented system constitutes an alternative method of the synthesis of metal hexacyanoferrate nanoparticles. PMID:22264404

  13. Phytochemicals and Biogenic Metallic Nanoparticles as Anticancer Agents

    PubMed Central

    Rao, Pasupuleti Visweswara; Nallappan, Devi; Madhavi, Kondeti; Rahman, Shafiqur; Jun Wei, Lim; Gan, Siew Hua

    2016-01-01

    Cancer is a leading cause of death worldwide. Several classes of drugs are available to treat different types of cancer. Currently, researchers are paying significant attention to the development of drugs at the nanoscale level to increase their target specificity and to reduce their concentrations. Nanotechnology is a promising and growing field with multiple subdisciplines, such as nanostructures, nanomaterials, and nanoparticles. These materials have gained prominence in science due to their size, shape, and potential efficacy. Nanomedicine is an important field involving the use of various types of nanoparticles to treat cancer and cancerous cells. Synthesis of nanoparticles targeting biological pathways has become tremendously prominent due to the higher efficacy and fewer side effects of nanodrugs compared to other commercial cancer drugs. In this review, different medicinal plants and their active compounds, as well as green-synthesized metallic nanoparticles from medicinal plants, are discussed in relation to their anticancer activities. PMID:27057273

  14. Nanoparticle-induced unusual melting and solidification behaviours of metals.

    PubMed

    Ma, Chao; Chen, Lianyi; Cao, Chezheng; Li, Xiaochun

    2017-01-18

    Effective control of melting and solidification behaviours of materials is significant for numerous applications. It has been a long-standing challenge to increase the melted zone (MZ) depth while shrinking the heat-affected zone (HAZ) size during local melting and solidification of materials. In this paper, nanoparticle-induced unusual melting and solidification behaviours of metals are reported that effectively solve this long-time dilemma. By introduction of Al2O3 nanoparticles, the MZ depth of Ni is increased by 68%, while the corresponding HAZ size is decreased by 67% in laser melting at a pulse energy of 0.18 mJ. The addition of SiC nanoparticles shows similar results. The discovery of the unusual melting and solidification of materials that contain nanoparticles will not only have impacts on existing melting and solidification manufacturing processes, such as laser welding and additive manufacturing, but also on other applications such as pharmaceutical processing and energy storage.

  15. Nanoparticle-induced unusual melting and solidification behaviours of metals

    NASA Astrophysics Data System (ADS)

    Ma, Chao; Chen, Lianyi; Cao, Chezheng; Li, Xiaochun

    2017-01-01

    Effective control of melting and solidification behaviours of materials is significant for numerous applications. It has been a long-standing challenge to increase the melted zone (MZ) depth while shrinking the heat-affected zone (HAZ) size during local melting and solidification of materials. In this paper, nanoparticle-induced unusual melting and solidification behaviours of metals are reported that effectively solve this long-time dilemma. By introduction of Al2O3 nanoparticles, the MZ depth of Ni is increased by 68%, while the corresponding HAZ size is decreased by 67% in laser melting at a pulse energy of 0.18 mJ. The addition of SiC nanoparticles shows similar results. The discovery of the unusual melting and solidification of materials that contain nanoparticles will not only have impacts on existing melting and solidification manufacturing processes, such as laser welding and additive manufacturing, but also on other applications such as pharmaceutical processing and energy storage.

  16. Tunable plasmon polaritons in arrays of interacting metallic nanoparticles

    NASA Astrophysics Data System (ADS)

    Weick, Guillaume; Mariani, Eros

    2015-01-01

    We consider a simple cubic array of metallic nanoparticles supporting extended collective plasmons that arise from the near-field dipolar interaction between localized surface plasmons in each nanoparticle. We develop a fully analytical quantum theory of the strong-coupling regime between these collective plasmons and photons resulting in plasmon polaritons in the nanoparticle array. Remarkably, we show that the polaritonic band gap and the dielectric function of the metamaterial can be significantly modulated by the polarization of light. We unveil how such an anisotropic behavior in the plasmonic metamaterial is crucially mediated by the dipolar interactions between the nanoparticles despite the symmetry of the underlying lattice. Our results thus pave the way towards the realization of tunable quantum plasmonic metamaterials presenting interaction-driven birefringence.

  17. Noble metal nanoparticles: Optical forces, electrochemical Ostwald ripening, and photovoltage

    NASA Astrophysics Data System (ADS)

    Redmond, Peter

    This thesis describes three distinct aspects of the chemical properties of noble metal nanoparticles. The first chapter introduces the surface plasmon resonance of noble metal nanoparticles. The second chapter presents an electrodynamic model for the calculation of the attractive optical forces that arise when two dielectric particles are irradiated in a light field. These forces show resonances at dipolar plasmon wavelengths, similar to resonances in the near-field electromagnetic intensities. At MW/cm2 intensities, optical forces can be stronger than van der Waals forces. The third chapter investigates the size dependent electrochemical properties of silver nanoparticles. These thermally evaporated silver nanoparticles spontaneously evolve in size when immersed in pure water on conducting substrates. The process is understood through an electrochemical Ostwald ripening mechanism driven by the size dependence of the work function and standard electrode potential. The fourth and fifth chapters consider photo-induced surface reactivity of noble metal particles. First, in the fourth chapter, the light driven deposition of copper onto gold nanoparticle electrodes is presented. The photocurrent is a nonlinear function of laser intensity and increases sharply with cathodic voltage in the underpotential deposition region. The photoreduction is attributed to laser heating (caused by decay of the plasmon oscillation) of the Au nanoparticles, rather than "hot electron" processes. Secondly, in the fifth chapter, the photo-induced oxidation of citrate is studied on silver nanoparticle electrodes. Irradiation of the citrate coated particles is shown to cause the particles to charge negatively from the irreversible transfer of electrons from citrate to the particles. It is hypothesized that the particle plasmon oscillation decays into electron hole pair(s) that causes the photo-oxidation of the surface bound citrate. Both the gold and silver particle systems are simulated using

  18. Fabrication of metallic microstructures by micromolding nanoparticles

    DOEpatents

    Morales, Alfredo M.; Winter, Michael R.; Domeier, Linda A.; Allan, Shawn M.; Skala, Dawn M.

    2002-01-01

    A method is provided for fabricating metallic microstructures, i.e., microcomponents of micron or submicron dimensions. A molding composition is prepared containing an optional binder and nanometer size (1 to 1000 nm in diameter) metallic particles. A mold, such as a lithographically patterned mold, preferably a LIGA or a negative photoresist mold, is filled with the molding composition and compressed. The resulting microstructures are then removed from the mold and the resulting metallic microstructures so provided are then sintered.

  19. Applications of metal nanoparticles in environmental cleanup

    EPA Science Inventory

    Iron nanoparticles (INPs) are one of the fastest-developing fields. INPs have a number of key physicochemical properties, such as high surface area, reactivity, optical and magnetic properties, and oxidation and reduction capacities, that make them attractive for water purificati...

  20. Adsorbate Diffusion on Transition Metal Nanoparticles

    DTIC Science & Technology

    2015-01-01

    systematically studied adsorption and diffusion of atomic and diatomic species (H, C, N, O, CO, and NO) on nanometer-sized Pt and Cu nanoparticles with...species and two diatomic molecules (H, C, N, O, CO, and NO) as adsorbates and study the adsorption and diffusion of these adsorbates across the edges

  1. Transition metal swift heavy ion implantation on 4H-SiC

    NASA Astrophysics Data System (ADS)

    Ali, A. Ashraf; Kumar, J.; Ramakrishnan, V.; Asokan, K.

    2016-03-01

    This work reports on the realization of Quantum Ring (QR) and Quantum Dot (QD) like structures on 4H-SiC through SHI implantation and on their Raman studies. 4H-SiC is SHI implanted with Transition Metal (TM) Ni ion at different fluences. It is observed that a vibrational mode emerges as the result of Ni ion implantation. The E2 (TO) and the A1 (LO) are suppressed as the fluence increases. In this paper Raman and AFM studies have been performed at room temperature and the queer anomalies are addressed so new devices can be fabricated.

  2. Metal nanoparticles via the atom-economy green approach.

    PubMed

    Kalidindi, Suresh Babu; Sanyal, Udishnu; Jagirdar, Balaji R

    2010-05-03

    Metal nanoparticles (NPs) of Cu (air-stable), Ag, and Au have been prepared using an atom-economy green approach. Simple mechanical stirring of solid mixtures (no solvent) of a metal salt and ammonia borane at 60 degrees C resulted in the formation of metal NPs. In this reaction, ammonia borane is transformed into a BNH(x) polymer, which protects the NPs formed and halts their growth. This results in the formation of the BNH(x) polymer protected monodisperse NPs. Thus, ammonia borane used in these reactions plays a dual role (reducing agent and precursor for the stabilizing agent).

  3. Hip Implant Systems

    MedlinePlus

    ... Devices Products and Medical Procedures Implants and Prosthetics Metal-on-Metal Hip Implants Hip Implants Share Tweet Linkedin Pin ... devices available with different bearing surfaces. These are: Metal-on-Polyethylene: The ball is made of metal ...

  4. Effect of Metals, Metalloids and Metallic Nanoparticles on Microalgae Growth and Industrial Product Biosynthesis: A Review

    PubMed Central

    Miazek, Krystian; Iwanek, Waldemar; Remacle, Claire; Richel, Aurore; Goffin, Dorothee

    2015-01-01

    Microalgae are a source of numerous compounds that can be used in many branches of industry. Synthesis of such compounds in microalgal cells can be amplified under stress conditions. Exposure to various metals can be one of methods applied to induce cell stress and synthesis of target products in microalgae cultures. In this review, the potential of producing diverse biocompounds (pigments, lipids, exopolymers, peptides, phytohormones, arsenoorganics, nanoparticles) from microalgae cultures upon exposure to various metals, is evaluated. Additionally, different methods to alter microalgae response towards metals and metal stress are described. Finally, possibilities to sustain high growth rates and productivity of microalgal cultures in the presence of metals are discussed. PMID:26473834

  5. Effect of Metals, Metalloids and Metallic Nanoparticles on Microalgae Growth and Industrial Product Biosynthesis: A Review.

    PubMed

    Miazek, Krystian; Iwanek, Waldemar; Remacle, Claire; Richel, Aurore; Goffin, Dorothee

    2015-10-09

    Microalgae are a source of numerous compounds that can be used in many branches of industry. Synthesis of such compounds in microalgal cells can be amplified under stress conditions. Exposure to various metals can be one of methods applied to induce cell stress and synthesis of target products in microalgae cultures. In this review, the potential of producing diverse biocompounds (pigments, lipids, exopolymers, peptides, phytohormones, arsenoorganics, nanoparticles) from microalgae cultures upon exposure to various metals, is evaluated. Additionally, different methods to alter microalgae response towards metals and metal stress are described. Finally, possibilities to sustain high growth rates and productivity of microalgal cultures in the presence of metals are discussed.

  6. Bismuth nanoparticles integration into heavy metal electrochemical stripping sensor.

    PubMed

    Cadevall, Miquel; Ros, Josep; Merkoçi, Arben

    2015-08-01

    Between their many applications bismuth nanoparticles (BiNPs) are showing interest as pre-concentrators in heavy metals detection while being applied as working electrode modifiers used in electrochemical stripping analysis. From the different reported methods to synthesize BiNPs we are focused on the typical polyol method, largely used in these types of metallic and semi-metallic nanoparticles. This study presents the strategy for an easy control of the shape and size of BiNPs including nanocubes, nanosferes and triangular nanostructures. To improve the BiNP size and shape, different reducing agents (ethylene glycol or sodium hypophosphite) and stabilizers (polyvinyl pyrrolidone, PVP, in different amounts) have been studied. The efficiency of BiNPs for heavy metals analysis in terms of detection sensitivity while being used as modifiers of screen-printed carbon electrodes including the applicability of the developed device in real sea water samples is shown. A parallel study between the obtained nanoparticles and their performance in heavy metal sensing has been described in this communication.

  7. Bulk Metallic Glass-like Scattering Signal in Small Metallic Nanoparticles

    SciTech Connect

    Doan-Nguyen, VVT; Kimber, SAJ; Pontoni, D; Hickey, DR; Diroll, BT; Yang, XH; Miglierini, M; Murray, CB; Billinge, SJL

    2014-06-01

    The atomic structure of Ni-Pd nanoparticles has been studied using atomic pair distribution function (PDF) analysis of X-ray total scattering data and with transmission electron microscopy (TEM). Larger nanoparticles have PDFs corresponding to the bulk face-centered cubic packing. However, the smallest nanoparticles have PDFs that strongly resemble those obtained from bulk metallic glasses (BMGs). In fact, by simply scaling the distance axis by the mean metallic radius, the curves may be collapsed onto each other and onto the PDF from a metallic glass sample. In common with a wide range of BMG materials, the intermediate range order may be fit with a damped single-frequency sine wave. When viewed in high-resolution TEM, these nanoparticles exhibit atomic fringes typical of those seen in small metallic clusters with icosahedral or decahedral order. These two seemingly contradictory results are reconciled by calculating the PDFs of models of icosahedra that would be consistent with the fringes seen in TEM. These model PDFs resemble the measured ones when significant atom-position disorder is introduced, drawing together the two diverse fields of metallic nanoparticles and BMGs and supporting the view that BMGs may contain significant icosahedral or decahedral order.

  8. Metallic nanoparticle deposition techniques for enhanced organic photovoltaic cells

    NASA Astrophysics Data System (ADS)

    Cacha, Brian Joseph Gonda

    Energy generation via organic photovoltaic (OPV) cells provide many advantages over alternative processes including flexibility and price. However, more efficient OPVs are required in order to be competitive for applications. One way to enhance efficiency is through manipulation of exciton mechanisms within the OPV, for example by inserting a thin film of bathocuproine (BCP) and gold nanoparticles between the C60/Al and ZnPc/ITO interfaces, respectively. We find that BCP increases efficiencies by 330% due to gains of open circuit voltage (Voc) by 160% and short circuit current (Jsc) by 130%. However, these gains are complicated by the anomalous photovoltaic effect and an internal chemical potential. Exploration in the tuning of metallic nanoparticle deposition on ITO was done through four techniques. Drop casting Ag nanoparticle solution showed arduous control on deposited morphology. Spin-coating deposited very low densities of nanoparticles. Drop casting and spin-coating methods showed arduous control on Ag nanoparticle morphology due to clustering and low deposition density, respectively. Sputtered gold on glass was initially created to aid the adherence of Ag nanoparticles but instead showed a quick way to deposit aggregated gold nanoparticles. Electrodeposition of gold nanoparticles (AuNP) proved a quick method to tune nanoparticle morphology on ITO substrates. Control of deposition parameters affected AuNP size and distribution. AFM images of electrodeposited AuNPs showed sizes ranging from 39 to 58 nm. UV-Vis spectroscopy showed the presence of localized plasmon resonance through absorption peaks ranging from 503 to 614 nm. A linear correlation between electrodeposited AuNP size and peak absorbance was seen with a slope of 3.26 wavelength(nm)/diameter(nm).

  9. Metal nanoparticles triggered persistent negative photoconductivity in silk protein hydrogels

    NASA Astrophysics Data System (ADS)

    Gogurla, Narendar; Sinha, Arun K.; Naskar, Deboki; Kundu, Subhas C.; Ray, Samit K.

    2016-03-01

    Silk protein is a natural biopolymer with intriguing properties, which are attractive for next generation bio-integrated electronic and photonic devices. Here, we demonstrate the negative photoconductive response of Bombyx mori silk protein fibroin hydrogels, triggered by Au nanoparticles. The room temperature electrical conductivity of Au-silk hydrogels is found to be enhanced with the incorporation of Au nanoparticles over the control sample, due to the increased charge transporting networks within the hydrogel. Au-silk lateral photoconductor devices show a unique negative photoconductive response under an illumination of 325 nm, with excitation energy higher than the characteristic metal plasmon resonance band. The enhanced photoconductance yield in the hydrogels over the silk protein is attributed to the photo-oxidation of amino groups in the β-pleated sheets of the silk around the Au nanoparticles followed by the breaking of charge transport networks. The Au-silk nanocomposite does not show any photoresponse under visible illumination because of the localization of excited charges in Au nanoparticles. The negative photoconductive response of hybrid Au-silk under UV illumination may pave the way towards the utilization of silk for future bio-photonic devices using metal nanoparticle platforms.

  10. Metal nanoparticles triggered persistent negative photoconductivity in silk protein hydrogels.

    PubMed

    Gogurla, Narendar; Sinha, Arun K; Naskar, Deboki; Kundu, Subhas C; Ray, Samit K

    2016-04-14

    Silk protein is a natural biopolymer with intriguing properties, which are attractive for next generation bio-integrated electronic and photonic devices. Here, we demonstrate the negative photoconductive response of Bombyx mori silk protein fibroin hydrogels, triggered by Au nanoparticles. The room temperature electrical conductivity of Au-silk hydrogels is found to be enhanced with the incorporation of Au nanoparticles over the control sample, due to the increased charge transporting networks within the hydrogel. Au-silk lateral photoconductor devices show a unique negative photoconductive response under an illumination of 325 nm, with excitation energy higher than the characteristic metal plasmon resonance band. The enhanced photoconductance yield in the hydrogels over the silk protein is attributed to the photo-oxidation of amino groups in the β-pleated sheets of the silk around the Au nanoparticles followed by the breaking of charge transport networks. The Au-silk nanocomposite does not show any photoresponse under visible illumination because of the localization of excited charges in Au nanoparticles. The negative photoconductive response of hybrid Au-silk under UV illumination may pave the way towards the utilization of silk for future bio-photonic devices using metal nanoparticle platforms.

  11. Evidence for the formation of SiGe nanoparticles in Ge-implanted Si3N4

    NASA Astrophysics Data System (ADS)

    Mirzaei, S.; Kremer, F.; Feng, R.; Glover, C. J.; Sprouster, D. J.

    2017-03-01

    SiGe nanoparticles were formed in an amorphous Si3N4 matrix by Ge+ ion implantation and thermal annealing. The size of the nanoparticles was determined by transmission electron microscopy and their atomic structure by x-ray absorption spectroscopy. Nanoparticles were observed for excess Ge concentrations in the range from 9 to 12 at. % after annealing at temperatures in the range from 700 to 900 °C. The average nanoparticle size increased with excess Ge concentration and annealing temperature and varied from an average diameter of 1.8 ± 0.2 nm for the lowest concentration and annealing temperature to 3.2 ± 0.5 nm for the highest concentration and annealing temperature. Our study demonstrates that the structural properties of embedded SiGe nanoparticles in amorphous Si3N4 are sensitive to the implantation and post implantation conditions. Furthermore, we demonstrate that ion implantation is a novel pathway to fabricate and control the SiGe nanoparticle structure and potentially useful for future optoelectronic device applications.

  12. A light and scanning electron microscopy study of human direct laser metal forming dental implants.

    PubMed

    Mangano, Carlo; Piattelli, Adriano; Scarano, Antonio; Raspanti, Mario; Shibli, Jamil A; Mangano, Francesco G; Perrotti, Vittoria; Iezzi, Giovanna

    2014-01-01

    Direct laser metal forming (DLMF) is a procedure in which a high-power laser beam is directed on a metal powder bed and programmed to fuse particles according to a computer-aided design file, thus generating a thin metal layer. With DLMF, it is now possible to fabricate dental implants with a superficial porous surface. The aim of the present study was to evaluate the peri-implant soft tissues around human-retrieved DLMF dental implants. Collagen fibers, in the form of bundles, were oriented perpendicularly to a distance of 100 μm from the surface, where they became parallel, running in several directions. In some portions, only a few collagen fiber bundles appeared to be oriented perpendicularly or obliquely to the plane of the section. Collagen fibers appeared to form a dense chaotic three-dimensional network running in different, more or less parallel directions to the surface. Under scanning electron microscopy, an intimate contact of the fibrous matrix with the implant surface was evident, and some collagen bundles could be seen to bind directly to the metal surface. By changing the surface microtexture, it was possible to change the response of the peri-implant soft tissues.

  13. Building up strain in colloidal metal nanoparticle catalysts

    NASA Astrophysics Data System (ADS)

    Sneed, Brian T.; Young, Allison P.; Tsung, Chia-Kuang

    2015-07-01

    The focus on surface lattice strain in nanostructures as a fundamental research topic has gained momentum in recent years as scientists investigated its significant impact on the surface electronic structure and catalytic properties of nanomaterials. Researchers have begun to tell a more complete story of catalysis from a perspective which brings this concept to the forefront of the discussion. The nano-`realm' makes the effects of surface lattice strain, which acts on the same spatial scales, more pronounced due to a higher ratio of surface to bulk atoms. This is especially evident in the field of metal nanoparticle catalysis, where displacement of atoms on surfaces can significantly alter the sorption properties of molecules. In part, the concept of strain-engineering for catalysis opened up due to the achievements that were made in the synthesis of a more sophisticated nanoparticle library from an ever-expanding set of methodologies. Developing synthesis methods for metal nanoparticles with well-defined and strained architectures is a worthy goal that, if reached, will have considerable impact in the search for catalysts. In this review, we summarize the recent accomplishments in the area of surface lattice-strained metal nanoparticle synthesis, framing the discussion from the important perspective of surface lattice strain effects in catalysis.

  14. Note: An ion source for alkali metal implantation beneath graphene and hexagonal boron nitride monolayers on transition metals

    SciTech Connect

    Lima, L. H. de; Cun, H. Y.; Hemmi, A.; Kälin, T.; Greber, T.

    2013-12-15

    The construction of an alkali-metal ion source is presented. It allows the acceleration of rubidium ions to an energy that enables the penetration through monolayers of graphene and hexagonal boron nitride. Rb atoms are sublimated from an alkali-metal dispenser. The ionization is obtained by surface ionization and desorption from a hot high work function surface. The ion current is easily controlled by the temperature of ionizer. Scanning Tunneling Microscopy measurements confirm ion implantation.

  15. Restoration: Implant with Devastated Platform through Metal Post

    PubMed Central

    Juan, Del Valle Lovato

    2017-01-01

    Case Presentation. Implant prostheses are a successful treatment for replacing missing teeth. However, this treatment modality can have biological and mechanical complications causing serious problems for the dentist, as demonstrated in this clinical case. The patient presented with a fractured screw and a severely damaged implant hex connection that corresponded to the second premolar, upper left, stating that she unsuccessfully tried to remove the prosthetic screw, which was most likely to have been loose. After clinical and radiographic review, it was decided to remove small fragments of the fractured prosthetic screw inside the implant head. Removal by conventional methods was unsuccessful but was eventually achieved through use of a bur. Then it was possible to make a cast post (gold-palladium) and develop a fixed prosthesis (silver-palladium), which were attached with luting cement. A cast post (gold-palladium) was made and a fixed prosthesis was developed (silver-palladium), which were attached with luting cement, the same ones that can present mechanical complications such as fractures between the third and fourth thread of the implant, loosening of the abutment, and/or the prosthetic screw in individual crowns, most frequently in partially edentulous patients, mainly in the premolar and molar regions of the maxilla. Conclusion. Therefore the present technique used in this case is very simple, noninvasive, and useful to readers. PMID:28286678

  16. Chlorhexidine hexametaphosphate nanoparticles as a novel antimicrobial coating for dental implants.

    PubMed

    Wood, Natalie J; Jenkinson, Howard F; Davis, Sean A; Mann, Stephen; O'Sullivan, Dominic J; Barbour, Michele E

    2015-06-01

    Dental implants are an increasingly popular solution to missing teeth. Implants are prone to colonisation by pathogenic oral bacteria which can lead to inflammation, destruction of bone and ultimately implant failure. The aim of this study was to investigate the use of chlorhexidine (CHX) hexametaphosphate (HMP) nanoparticles (NPs) with a total CHX concentration equivalent to 5 mM as a coating for dental implants. The CHX HMP NPs had mean diameter 49 nm and composition was confirmed showing presence of both chlorine and phosphorus. The NPs formed micrometer-sized aggregated surface deposits on commercially pure grade II titanium substrates following immersion-coating for 30 s. When CHX HMP NP-coated titanium specimens were immersed in deionised water, sustained release of soluble CHX was observed, both in the absence and presence of a salivary pellicle, for the duration of the study (99 days) without reaching a plateau. Control specimens exposed to a solution of aqueous 25 µM CHX (equivalent to the residual aqueous CHX present with the NPs) did not exhibit CHX release. CHX HMP NP-coated surfaces exhibited antimicrobial efficacy against oral primary colonising bacterium Streptococcus gordonii within 8 h. The antimicrobial efficacy was greater in the presence of an acquired pellicle which is postulated to be due to retention of soluble CHX by the pellicle.

  17. Formation of c-BN nanoparticles by helium, lithium and boron ion implantation

    NASA Astrophysics Data System (ADS)

    Aradi, Emily; Erasmus, Rudolph M.; Derry, Trevor E.

    2012-02-01

    Ion induced phase transformation from the soft graphitic hexagonal boron nitride ( h-BN) to ultrahard cubic boron nitride ( c-BN) nanoparticles is presented in the work herein. Ion implantation was used as a technique to introduce boron lithium and helium ions, at the energy of 150 keV and fluences ranging from 1 × 10 14 to 1 × 10 16 ions/cm 2, into hot pressed, polycrystalline h-BN. Analyses using Raman Spectroscopy showed that He +, Li + and B + led to a h-BN to c-BN phase transition, evident from the longitudinal optical (LO) Raman phonon features occurring in the implanted samples' spectra. The nature of these phonon peaks and their downshifting is explained using the spatial phonon correlation model.

  18. Metal Nanoparticles Preparation In Supercritical Carbon Dioxide Solutions

    SciTech Connect

    Harry W. Rollins

    2004-04-01

    The novel optical, electronic, and/or magnetic properties of metal and semiconductor nanoparticles have resulted in extensive research on new methods for their preparation. An ideal preparation method would allow the particle size, size distribution, crystallinity, and particle shape to be easily controlled, and would be applicable to a wide variety of material systems. Numerous preparation methods have been reported, each with its inherent advantages and disadvantages; however, an ideal method has yet to emerge. The most widely applied methods for nanoparticle preparation include the sonochemical reduction of organometallic reagents,(1&2) the solvothermal method of Alivisatos,(3) reactions in microemulsions,(4-6) the polyol method (reduction by alcohols),(7-9) and the use of polymer and solgel materials as hosts.(10-13) In addition to these methods, there are a variety of methods that take advantage of the unique properties of a supercritical fluid.(14&15) Through simple variations of temperature and pressure, the properties of a supercritical fluid can be continuously tuned from gas-like to liquid-like without undergoing a phase change. Nanoparticle preparation methods that utilize supercritical fluids are briefly reviewed below using the following categories: Rapid Expansion of Supercritical Solutions (RESS), Reactive Supercritical Fluid Processing, and Supercritical Fluid Microemulsions. Because of its easily accessible critical temperature and pressure and environmentally benign nature, carbon dioxide is the most widely used supercritical solvent. Supercritical CO2 is unfortunately a poor solvent for many polar or ionic species, which has impeded its use in the preparation of metal and semiconductor nanoparticles. We have developed a reactive supercritical fluid processing method using supercritical carbon dioxide for the preparation of metal and metal sulfide particles and used it to prepare narrowly distributed nanoparticles of silver (Ag) and silver sulfide

  19. Impact of metallic and metal oxide nanoparticles on wastewater treatment and anaerobic digestion.

    PubMed

    Yang, Yu; Zhang, Chiqian; Hu, Zhiqiang

    2013-01-01

    Metallic and metal oxide nanomaterials have been increasingly used in consumer products (e.g. sunscreen, socks), the medical and electronic industries, and environmental remediation. Many of them ultimately enter wastewater treatment plants (WWTPs) or landfills. This review paper discusses the fate and potential effects of four types of nanoparticles, namely, silver nanoparticles (AgNPs), nano ZnO, nano TiO2, and nano zero valent iron (NZVI), on waste/wastewater treatment and anaerobic digestion. The stabilities and chemical properties of these nanoparticles (NPs) result in significant differences in antimicrobial activities. Analysis of published data of metallic and metal oxide NPs suggests that oxygen is often a prerequisite for the generation of reactive oxygen species (ROS) for AgNPs and NZVI, while illumination is necessary for ROS generation for nano TiO2 and nano ZnO. Furthermore, such nanoparticles are capable of being oxidized or dissolved in water and can release metal ions, leading to metal toxicity. Therefore, AgNPs and nano TiO2 are chemically stable NPs that have no adverse effects on microbes under anaerobic conditions. Although the toxicity of nanomaterials has been studied intensively under aerobic conditions, more research is needed to address their fate in anaerobic waste/wastewater treatment systems and their long-term effects on the environment.

  20. Biosynthesis of Metal Nanoparticles: Novel Efficient Heterogeneous Nanocatalysts

    PubMed Central

    Palomo, Jose M.; Filice, Marco

    2016-01-01

    This review compiles the most recent advances described in literature on the preparation of noble metal nanoparticles induced by biological entities. The use of different free or substituted carbohydrates, peptides, proteins, microorganisms or plants have been successfully applied as a new green concept in the development of innovative strategies to prepare these nanoparticles as different nanostructures with different forms and sizes. As a second part of this review, the application of their synthetic ability as new heterogonous catalysts has been described in C–C bond-forming reactions (as Suzuki, Heck, cycloaddition or multicomponent), oxidations and dynamic kinetic resolutions. PMID:28335213

  1. Nonlocal effects in metallic nanoparticles: The kinetic approach outlook

    NASA Astrophysics Data System (ADS)

    Tomchuk, Petro M.; Butenko, Danylo

    2017-02-01

    For the metallic nanoparticles, smaller than the free electron path, an impact of the particle’s surface on the nonlocal effects emerging is shown. Light-induced current inside the particle begins to depend on the spatial derivatives of the field that leads to modification of Maxwell’s equations. Consequently, the results of Mie theory as well as definitions of the dielectric function and optical conductivity should be revisited. For the sphere-shaped nanoparticle, the explicit expression for the high-frequency current with account of nonlocality is obtained. The dependence of the nonlocal contribution on the light frequency and particle’s size is discussed.

  2. Spectral variation of fluorescence lifetime near single metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Li, Jia; Krasavin, Alexey V.; Webster, Linden; Segovia, Paulina; Zayats, Anatoly V.; Richards, David

    2016-02-01

    We explore the spectral dependence of fluorescence enhancement and the associated lifetime modification of fluorescent molecules coupled to single metal nanoparticles. Fluorescence lifetime imaging microscopy and single-particle dark-field spectroscopy are combined to correlate the dependence of fluorescence lifetime reduction on the spectral overlap between the fluorescence emission and the localised surface plasmon (LSP) spectra of individual gold nanoparticles. A maximum lifetime reduction is observed when the fluorescence and LSP resonances coincide, with good agreement provided by numerical simulations. The explicit comparison between experiment and simulation, that we obtain, offers an insight into the spectral engineering of LSP mediated fluorescence and may lead to optimized application in sensing and biomedicine.

  3. Self-assembly of noble metal monolayers on transition metal carbide nanoparticle catalysts.

    PubMed

    Hunt, Sean T; Milina, Maria; Alba-Rubio, Ana C; Hendon, Christopher H; Dumesic, James A; Román-Leshkov, Yuriy

    2016-05-20

    We demonstrated the self-assembly of transition metal carbide nanoparticles coated with atomically thin noble metal monolayers by carburizing mixtures of noble metal salts and transition metal oxides encapsulated in removable silica templates. This approach allows for control of the final core-shell architecture, including particle size, monolayer coverage, and heterometallic composition. Carbon-supported Ti(0.1)W(0.9)C nanoparticles coated with Pt or bimetallic PtRu monolayers exhibited enhanced resistance to sintering and CO poisoning, achieving an order of magnitude increase in specific activity over commercial catalysts for methanol electrooxidation after 10,000 cycles. These core-shell materials provide a new direction to reduce the loading, enhance the activity, and increase the stability of noble metal catalysts.

  4. Plasmon Response and Electron Dynamics in Charged Metallic Nanoparticles.

    PubMed

    Zapata Herrera, Mario; Aizpurua, Javier; Kazansky, Andrey K; Borisov, Andrei G

    2016-03-22

    Using the time-dependent density functional theory, we perform quantum calculations of the electron dynamics in small charged metallic nanoparticles (clusters) of spherical geometry. We show that the excess charge is accumulated at the surface of the nanoparticle within a narrow layer given by the typical screening distance of the electronic system. As a consequence, for nanoparticles in vacuum, the dipolar plasmon mode displays only a small frequency shift upon charging. We obtain a blue shift for positively charged clusters and a red shift for negatively charged clusters, consistent with the change of the electron spill-out from the nanoparticle boundaries. For negatively charged clusters, the Fermi level is eventually promoted above the vacuum level leading to the decay of the excess charge via resonant electron transfer into the continuum. We show that, depending on the charge, the process of electron loss can be very fast, on the femtosecond time scale. Our results are of great relevance to correctly interpret the optical response of the nanoparticles obtained in electrochemistry, and demonstrate that the measured shift of the plasmon resonances upon charging of nanoparticles cannot be explained without account for the surface chemistry and the dielectric environment.

  5. Is Neurotoxicity of Metallic Nanoparticles the Cascades of Oxidative Stress?

    NASA Astrophysics Data System (ADS)

    Song, Bin; Zhang, YanLi; Liu, Jia; Feng, XiaoLi; Zhou, Ting; Shao, LongQuan

    2016-06-01

    With the rapid development of nanotechnology, metallic (metal or metal oxide) nanoparticles (NPs) are widely used in many fields such as cosmetics, the food and building industries, and bio-medical instruments. Widespread applications of metallic NP-based products increase the health risk associated with human exposures. Studies revealed that the brain, a critical organ that consumes substantial amounts of oxygen, is a primary target of metallic NPs once they are absorbed into the body. Oxidative stress (OS), apoptosis, and the inflammatory response are believed to be the main mechanisms underlying the neurotoxicity of metallic NPs. Other studies have disclosed that antioxidant pretreatment or co-treatment can reverse the neurotoxicity of metallic NPs by decreasing the level of reactive oxygen species, up-regulating the activities of antioxidant enzymes, decreasing the proportion of apoptotic cells, and suppressing the inflammatory response. These findings suggest that the neurotoxicity of metallic NPs might involve a cascade of events following NP-induced OS. However, additional research is needed to determine whether NP-induced OS plays a central role in the neurotoxicity of metallic NPs, to develop a comprehensive understanding of the correlations among neurotoxic mechanisms and to improve the bio-safety of metallic NP-based products.

  6. Gentamicin coating of metallic implants reduces implant-related osteomyelitis in rats.

    PubMed

    Lucke, M; Schmidmaier, G; Sadoni, S; Wildemann, B; Schiller, R; Haas, N P; Raschke, M

    2003-05-01

    Antibiotic prophylaxis is a routine procedure in orthopedic surgery. Various local antibiotic delivery techniques are used to reduce bone- and soft tissue-related infection. The objective of this study was to evaluate the efficacy of a new biodegradable, gentamicin-loaded poly(D,L-lactide) (PDLLA) coating of orthopedic devices in preventing implant-related osteomyelitis. The medullary cavities of tibiae in 30 Sprague Dawley rats were contaminated with Staphylococcus aureus (10(3) colony forming units). Simultaneously titanium Kirschner wires, uncoated (group II), coated with PDLLA (group III), or coated with PDLLA + 10% gentamicin (group IV), were implanted. Ten animals that received phosphate-buffered saline and uncoated Kirschner wires served as controls (group I). Follow-up was 6 weeks. In weekly intervals X-rays of the tibiae were performed, blood counts were taken, and body temperature and weight were determined. After sacrifice infection was evaluated by histological and microbiological analysis. All animals of groups II and III developed microbiological, histological, and radiological signs of infection, including osseous destruction and soft tissue swelling. All animals of the control group remained sterile. Cultures of implants of group IV showed significantly reduced bacterial growth compared to cultures of groups II and III, and three implants of group IV remained sterile. Further radiological and histological signs of infection were significantly reduced in the gentamicin-coated group compared to groups II and III. No significant differences in body weight, body temperature, and blood parameters between all groups were observed. Local application of antibiotic-coated orthopedic devices containing PDLLA and 10% gentamicin significantly reduced implant-related infection in this animal model.

  7. Antimicrobial properties of metal and metal-halide nanoparticles and their potential applications

    NASA Astrophysics Data System (ADS)

    Torrey, Jason Robert

    Heavy metals, including silver and copper, have been known to possess antimicrobial properties against bacterial, fungal, and viral pathogens. Metal nanoparticles (aggregations of metal atoms 1-200 nm in size) have recently become the subject of intensive study for their increased antimicrobial properties. In the current studies, metal and metal-halide nanoparticles were evaluated for their antibacterial efficacy. Silver (Ag), silver bromide (AgBr), silver iodide (AgI), and copper iodide (CuI) nanoparticles significantly reduced bacterial numbers of the Gram-negative Pseudomonas aeruginosa and the Gram-positive Staphylococcus aureus within 24 hours and were more effective against P. aeruginosa. CuI nanoparticles were found to be highly effective, reducing both organisms by >4.43 log 10 within 15 minutes at 60 ppm Cu. CuI nanoparticles formulated with different stabilizers (sodium dodecyl sulfate, SDS; polyvinyl pyrrolidone, PVP) were further tested against representative Gram-positive and Gram-negative bacteria, Mycobacteria, a fungus (Candida albicans ), and a non-enveloped virus (poliovirus). Both nanoparticles caused significant reductions in most of the Gram-negative bacteria within five minutes (>5.09-log10). The Gram-positive bacterial species and C. albicans were more sensitive to the CuI-SDS than the CuI-PVP nanoparticles. In contrast, the acid-fast Mycobacterium smegmatis was more resistant to CuI-SDS than CuI-PVP nanoparticles. Poliovirus was more resistant than the other organisms tested except for Mycobacterium fortuitum, which displayed the greatest resistance to CuI nanoparticles. As an example of a real world antimicrobial application, polymer coatings embedded with various concentrations of CuI nanoparticles were tested for antibacterial efficacy against P. aeruginosa and S. aureus. Polyester-epoxy powder coatings were found to display superior uniformity, stability and antimicrobial properties against both organisms (>4.92 log 10 after six hours at

  8. A novel electrode surface fabricated by directly attaching gold nanoparticles onto NH2+ ions implanted-indium tin oxide substrate

    NASA Astrophysics Data System (ADS)

    Liu, Chenyao; Jiao, Jiao; Chen, Qunxia; Xia, Ji; Li, Shuoqi; Hu, Jingbo; Li, Qilong

    2010-12-01

    A new type of gold nanoparticle attached to a NH2+ ion implanted-indium tin oxide surface was fabricated without using peculiar binder molecules, such as 3-(aminopropyl)-trimethoxysilane. A NH 2/indium tin oxide film was obtained by implantation at an energy of 80 keV with a fluence of 5 × 10 15 ions/cm 2. The gold nanoparticle-modified film was characterized by X-ray photoelectron spectroscopy, scanning electron microscopy and electrochemical techniques and compared with a modified bare indium tin oxide surface and 3-(aminopropyl)-trimethoxysilane linked surface, which exhibited a relatively low electron transfer resistance and high electrocatalytic activity. The results demonstrate that NH2+ ion implanted-indium tin oxide films can provide an important route to immobilize nanoparticles, which is attractive in developing new biomaterials.

  9. Theoretic investigation on plasmonics of noble metallic nanoparticles

    NASA Astrophysics Data System (ADS)

    Qian, Xiaohu

    In this thesis, we report our theoretic investigation on the surface plasmon polaritons of noble metallic nanoparticles and its applications. By means of numerical experiments, we studied the general far-field and near-field optical properties of the promising hollow metallic nanoparticles, the pattern of far-field extinction efficiency and the near-field surface-enhanced Raman scattering. We demonstrated the distribution of plasmon resonance wavelength as functions of the geometrical factor of hollow spherical gold and silver nanostructures. In addition, we utilized a novel mechanism of harnessing the mechanical strain to controllably tailor the plasmon-based optical spectra of single metallic nanospheres and the array of metallic nanoparticle of spheres and circular discs. The second goal of this thesis is to utilize a novel mechanical-strain-induced effect to enhance the light-trapping performance of plasmonic solar cells. This multi-physical scheme has the potential of considerably reducing the thickness of semiconductor layer and hence save the cost of production of the solar cells. Corresponding simulation results demonstrated this strategy is promising to decrease the fabrication budget of solar industry.

  10. Physicochemical Factors that Affect Metal and Metal Oxide Nanoparticle Passage Across Epithelial Barriers

    PubMed Central

    Elder, Alison; Vidyasagar, Sadasivan; DeLouise, Lisa

    2014-01-01

    The diversity of nanomaterials in terms of size, shape, and surface chemistry poses a challenge to those who are trying to characterize the human health and environmental risks associated with incidental and unintentional exposures. There are numerous products that are already commercially available that contain solid metal and metal oxide nanoparticles, either embedded in a matrix or in solution. Exposure assessments for these products are often incomplete or difficult due to technological challenges associated with detection and quantitation of nanoparticles in gaseous or liquid carriers. The main focus of recent research has been on hazard identification. However, risk is a product of hazard and exposure, and one significant knowledge gap is that of the target organ dose following in vivo exposures. In order to reach target organs, nanoparticles must first breech the protective barriers of the respiratory tract, gastrointestinal tract, or skin. The fate of those nanoparticles that reach physiological barriers is in large part determined by the properties of the particles and the barriers themselves. This article reviews the physiological properties of the lung, gut, and skin epithelia, the physicochemical properties of metal and metal oxide nanoparticles that are likely to affect their ability to breech epithelial barriers, and what is known about their fate following in vivo exposures. PMID:20049809

  11. Homogeneous Media Milling: Reactant-Assisted Mechanochemical Synthesis of Functionalized Nanoparticles from Malleable and Ductile Metals

    DTIC Science & Technology

    2014-01-01

    Reactant-Assisted Mechanochemical Synthesis of Functionalized Nanoparticles from Malleable and Ductile Metals 5b. GRANT NUMBER 5c. PROGRAM...Mechanochemical Synthesis of Functionalized Nanoparticles from Malleable and Ductile Metals Brandon W. McMahon†, Jesus Paulo L. Perez†, Jiang Yu†, Jerry A...confirming the dominance of bridging bidentate binding. *Corresponding Author aSenior Author Keywords: Milling, wear, nanoparticle synthesis

  12. Biological Strategies for Improved Osseointegration and Osteoinduction of Porous Metal Orthopedic Implants

    PubMed Central

    Riester, Scott M.; Bonin, Carolina A.; Kremers, Hilal Maradit; Dudakovic, Amel; Kakar, Sanjeev; Cohen, Robert C.; Westendorf, Jennifer J.

    2015-01-01

    The biological interface between an orthopedic implant and the surrounding host tissue may have a dramatic effect upon clinical outcome. Desired effects include bony ingrowth (osseointegration), stimulation of osteogenesis (osteoinduction), increased vascularization, and improved mechanical stability. Implant loosening, fibrous encapsulation, corrosion, infection, and inflammation, as well as physical mismatch may have deleterious clinical effects. This is particularly true of implants used in the reconstruction of load-bearing synovial joints such as the knee, hip, and the shoulder. The surfaces of orthopedic implants have evolved from solid-smooth to roughened-coarse and most recently, to porous in an effort to create a three-dimensional architecture for bone apposition and osseointegration. Total joint surgeries are increasingly performed in younger individuals with a longer life expectancy, and therefore, the postimplantation lifespan of devices must increase commensurately. This review discusses advancements in biomaterials science and cell-based therapies that may further improve orthopedic success rates. We focus on material and biological properties of orthopedic implants fabricated from porous metal and highlight some relevant developments in stem-cell research. We posit that the ideal primary and revision orthopedic load-bearing metal implants are highly porous and may be chemically modified to induce stem cell growth and osteogenic differentiation, while minimizing inflammation and infection. We conclude that integration of new biological, chemical, and mechanical methods is likely to yield more effective strategies to control and modify the implant–bone interface and thereby improve long-term clinical outcomes. PMID:25348836

  13. Mechanistic analysis of Zein nanoparticles/PLGA triblock in situ forming implants for glimepiride

    PubMed Central

    Ahmed, Osama Abdelhakim Aly; Zidan, Ahmed Samir; Khayat, Maan

    2016-01-01

    Objectives The study aims at applying pharmaceutical nanotechnology and D-optimal fractional factorial design to screen and optimize the high-risk variables affecting the performance of a complex drug delivery system consisting of glimepiride–Zein nanoparticles and inclusion of the optimized formula with thermoresponsive triblock copolymers in in situ gel. Methods Sixteen nanoparticle formulations were prepared by liquid–liquid phase separation method according to the D-optimal fractional factorial design encompassing five variables at two levels. The responses investigated were glimepiride entrapment capacity (EC), particle size and size distribution, zeta potential, and in vitro drug release from the prepared nanoparticles. Furthermore, the feasibility of embedding the optimized Zein-based glimepiride nanoparticles within thermoresponsive triblock copolymers poly(lactide-co-glycolide)-block-poly(ethylene glycol)-block-poly(lactide-co-glycolide) in in situ gel was evaluated for controlling glimepiride release rate. Results Through the systematic optimization phase, improvement of glimepiride EC of 33.6%, nanoparticle size of 120.9 nm with a skewness value of 0.2, zeta potential of 11.1 mV, and sustained release features of 3.3% and 17.3% drug released after 2 and 24 hours, respectively, were obtained. These desirability functions were obtained at Zein and glimepiride loadings of 50 and 75 mg, respectively, utilizing didodecyldimethylammonium bromide as a stabilizer at 0.1% and 90% ethanol as a common solvent. Moreover, incorporating this optimized formulation in triblock copolymers-based in situ gel demonstrated pseudoplastic behavior with reduction of drug release rate as the concentration of polymer increased. Conclusion This approach to control the release of glimepiride using Zein nanoparticles/triblock copolymers-based in situ gel forming intramuscular implants could be useful for improving diabetes treatment effectiveness. PMID:26893561

  14. Maxillary overdentures supported by four splinted direct metal laser sintering implants: a 3-year prospective clinical study.

    PubMed

    Mangano, Francesco; Luongo, Fabrizia; Shibli, Jamil Awad; Anil, Sukumaran; Mangano, Carlo

    2014-01-01

    Purpose. Nowadays, the advancements in direct metal laser sintering (DMLS) technology allow the fabrication of titanium dental implants. The aim of this study was to evaluate implant survival, complications, and peri-implant marginal bone loss of DMLS implants used to support bar-retained maxillary overdentures. Materials and Methods. Over a 2-year period, 120 implants were placed in the maxilla of 30 patients (18 males, 12 females) to support bar-retained maxillary overdentures (ODs). Each OD was supported by 4 implants splinted by a rigid cobalt-chrome bar. At each annual follow-up session, clinical and radiographic parameters were assessed. The outcome measures were implant failure, biological and prosthetic complications, and peri-implant marginal bone loss (distance between the implant shoulder and the first visible bone-to-implant contact, DIB). Results. The 3-year implant survival rate was 97.4% (implant-based) and 92.9% (patient-based). Three implants failed. The incidence of biological complication was 3.5% (implant-based) and 7.1% (patient-based). The incidence of prosthetic complication was 17.8% (patient-based). No detrimental effects on marginal bone level were evidenced. Conclusions. The use of 4 DMLS titanium implants to support bar-retained maxillary ODs seems to represent a safe and successful procedure. Long-term clinical studies on a larger sample of patients are needed to confirm these results.

  15. Maxillary Overdentures Supported by Four Splinted Direct Metal Laser Sintering Implants: A 3-Year Prospective Clinical Study

    PubMed Central

    Mangano, Francesco; Shibli, Jamil Awad; Anil, Sukumaran

    2014-01-01

    Purpose. Nowadays, the advancements in direct metal laser sintering (DMLS) technology allow the fabrication of titanium dental implants. The aim of this study was to evaluate implant survival, complications, and peri-implant marginal bone loss of DMLS implants used to support bar-retained maxillary overdentures. Materials and Methods. Over a 2-year period, 120 implants were placed in the maxilla of 30 patients (18 males, 12 females) to support bar-retained maxillary overdentures (ODs). Each OD was supported by 4 implants splinted by a rigid cobalt-chrome bar. At each annual follow-up session, clinical and radiographic parameters were assessed. The outcome measures were implant failure, biological and prosthetic complications, and peri-implant marginal bone loss (distance between the implant shoulder and the first visible bone-to-implant contact, DIB). Results. The 3-year implant survival rate was 97.4% (implant-based) and 92.9% (patient-based). Three implants failed. The incidence of biological complication was 3.5% (implant-based) and 7.1% (patient-based). The incidence of prosthetic complication was 17.8% (patient-based). No detrimental effects on marginal bone level were evidenced. Conclusions. The use of 4 DMLS titanium implants to support bar-retained maxillary ODs seems to represent a safe and successful procedure. Long-term clinical studies on a larger sample of patients are needed to confirm these results. PMID:25580124

  16. Harmonic nanoparticles: noncentrosymmetric metal oxides for nonlinear optics

    NASA Astrophysics Data System (ADS)

    Rogov, Andrii; Mugnier, Yannick; Bonacina, Luigi

    2015-03-01

    The combination of nonlinear optics and nanotechnology is an extremely rich scientific domain yet widely unexplored. We present here a review of recent optical investigations on noncentrosymmetric oxide nanoparticles with a large {{χ }(2)} response, often referred to as harmonic nanoparticles (HNPs). HNPs feature a series of properties which distinguish them from other photonics nanoprobes (quantum dots, up-conversion nanoparticles, noble metal particles). HNPs emission is inherently nonlinear and based on the efficient generation of harmonics as opposed to fluorescence or surface plasmon scattering. In addition, the fully coherent signal emitted by HNPs together with their polarization sensitive response and absence of resonant interaction make them appealing for several applications ranging from multi-photon (infrared) microscopy and holography, to cell tracking and sensing.

  17. Dynamic inclusion complexes of metal nanoparticles inside nanocups.

    PubMed

    Alarcón-Correa, Mariana; Lee, Tung-Chun; Fischer, Peer

    2015-06-01

    Host-guest inclusion complexes are abundant in molecular systems and of fundamental importance in living organisms. Realizing a colloidal analogue of a molecular dynamic inclusion complex is challenging because inorganic nanoparticles (NPs) with a well-defined cavity and portal are difficult to synthesize in high yield and with good structural fidelity. Herein, a generic strategy towards the fabrication of dynamic 1:1 inclusion complexes of metal nanoparticles inside oxide nanocups with high yield (>70%) and regiospecificity (>90%) by means of a reactive double Janus nanoparticle intermediate is reported. Experimental evidence confirms that the inclusion complexes are formed by a kinetically controlled mechanism involving a delicate interplay between bipolar galvanic corrosion and alloying-dealloying oxidation. Release of the NP guest from the nanocups can be efficiently triggered by an external stimulus.

  18. Design strategies of hybrid metallic nanoparticles for theragnostic applications

    NASA Astrophysics Data System (ADS)

    Gautier, J.; Allard-Vannier, E.; Hervé-Aubert, K.; Soucé, M.; Chourpa, I.

    2013-11-01

    Metallic nanoparticles (MNPs) such as iron oxide and gold nanoparticles are interesting platforms to build theragnostic nanocarriers which combine both therapeutic and diagnostic functions within a single nanostructure. Nevertheless, their surface must be functionalized to be suitable for in vivo applications. Surface functionalization also provides binding sites for targeting ligands, and for drug loading. This review focuses on the materials and surface chemistry used to build hybrid nanocarriers that are inorganic cores functionalized with organic materials. The surface state of the MNPs largely depends on their synthesis routes, and dictates the strategies used for functionalization. Two main strategies can be found in the literature: the design of core-shell nanosystems, or embedding nanoparticles in organic materials. Emerging tendencies such as the use of clusters or alternative coating materials are also described. To present both hydrophilic and lipophilic nanosystems, we chose the doxorubicin anticancer agent as an example, as the molecule presents an affinity for both types of materials.

  19. Scaling laws in superlubric sliding of metallic nanoparticles

    NASA Astrophysics Data System (ADS)

    Feldmann, Michael; Dietzel, Dirk; Moenninghoff, Tristan; Schirmeisen, Andre; Schwarz, Udo D.

    2010-03-01

    If an interface between two incommensurate surfaces is atomically clean, a state of virtually frictionless sliding is anticipated, often referred to as ``superlubricity.'' Theory predicts that the lattice mismatch at the interface causes a decrease of shear stress with increasing contact area, ultimately leading to vanishing friction. Analyzing the contact area dependence of superlubric friction should therefore confirm the concept of superlubricity. To measure the interfacial friction we have manipulated metallic nanoparticles of different size on atomically flat surfaces by contact mode atomic force microscopy techniques. An optimized experimental setup allowed us to quantify friction of nanoparticles which previously appeared to be sliding frictionless [1]. As theoretically expected, interfacial friction showed a nonlinear contact area dependence with a shear stress decreasing with contact area. This confirms the superlubric sliding of the nanoparticles under investigation. [4pt] [1] Dietzel et al., Phys. Rev. Lett. 101, 125505 (2008).

  20. Metallic ion content and damage to the DNA in oral mucosa cells patients treated dental implants.

    PubMed

    López-Jornet, Pía; Perrez, Francisco Parra; Calvo-Guirado, José Luis; Ros-Llor, Irene; LLor-Ros, Irene; Ramírez-Fernández, Piedad

    2014-07-01

    The aim of this study was to assess the potential genotoxicity of dental implants, evaluating biomarkers of DNA damage (micronuclei and/or nuclear buds), cytokinetic defects (binucleated cells) and the presence of trace metals in gingival cells of patients with implants, comparing these with a control group. A total of 60 healthy adults (30 patients with dental implants and 30 control patients without) were included in the study. Medical and dental histories were made for each including life-style factors. Genotoxicity effects were assessed by micronucleus assays in the gingival epithelial cells of each patient; 1,000 epithelial cells were analyzed, evaluating the frequency of micronucleated cells and other nuclear anomalies. The concentration of metals (Al(27), Ag(107), Co (59), Cr (52), Cu(63), Fe(56), Sn(118), Mn(55), Mo(92), Ni(60), Pb(208), Ti(47)) were assayed by means of coupled plasma-mass spectrophotometry (ICP-MS). The frequency of micronuclei in the patient group with implants was higher than in the control group but without statistically significant differences (P > 0.05). Similar results were found for binucleated cells and nuclear buds (P > 0.05). For metals assayed by ICP-MS, significant differences were found for Ti(47) (P ≤ 0.045). Univariate analysis identified a significant association between the presence of micronuclei and age. Dental implants do not induce DNA damage in gingival cells, the slight effects observed cannot be indicated as biologically relevant.

  1. Magnetic resonance imaging metallic artifact of commonly encountered surgical implants and foreign material.

    PubMed

    Sutherland-Smith, James; Tilley, Brenda

    2012-01-01

    Magnetic resonance imaging (MRI) artifacts secondary to metallic implants and foreign bodies are well described. Herein, we provide quantitative data from veterinary implants including total hip arthroplasty implants, cranial cruciate repair implants, surgical screws, a skin staple, ligation clips, an identification microchip, ameroid constrictor, and potential foreign bodies including air gun and BB projectiles and a sewing needle. The objects were scanned in a gelatin phantom with plastic grid using standardized T2-weighted turbo-spin echo (TSE), T1-weighted spin echo, and T2*-weighted gradient recalled echo (GRE) image acquisitions at 1.5 T. Maximum linear dimensions and areas of signal voiding and grid distortion were calculated using a DICOM workstation for each sequence and object. Artifact severity was similar between the T2-weighted TSE and T1-weighted images, while the T2*-weighted images were most susceptible to artifact. Metal type influenced artifact size with the largest artifacts arising from steel objects followed by surgical stainless steel, titanium, and lead. For animals with metallic surgical implants or foreign bodies, the quantification of the artifact size will help guide clinicians on the viability of MRI.

  2. Safety of magnetic resonance imaging in patients with implanted cardiac prostheses and metallic cardiovascular electronic devices.

    PubMed

    Baikoussis, Nikolaos G; Apostolakis, Efstratios; Papakonstantinou, Nikolaos A; Sarantitis, Ioannis; Dougenis, Dimitrios

    2011-06-01

    Magnetic resonance imaging (MRI) in patients with implanted cardiac prostheses and metallic cardiovascular electronic devices is sometimes a risky procedure. Thus MRI in these patients should be performed when it is the only examination able to help with the diagnosis. Moreover the diagnostic benefit must outweigh the risks. Coronary artery stents, prosthetic cardiac valves, metal sternal sutures, mediastinal vascular clips, and epicardial pacing wires are not contraindications for MRI, in contrast to pacemakers and implantable cardioverter-defibrillators. Appropriate patient selection and precautions ensure MRI safety. However it is commonly accepted that although hundreds of patients with pacemakers or implantable cardioverter-defibrillators have undergone safe MRI scanning, it is not a safe procedure. Currently, heating of the pacemaker lead is the major problem undermining MRI safety. According to the US Food and Drug Administration (FDA), there are currently neither "MRI-safe" nor "MRI-compatible" pacemakers and implantable cardioverter-defibrillators. In this article we review the international literature in regard to safety during MRI of patients with implanted cardiac prostheses and metallic cardiovascular electronic devices.

  3. Surface modification of metal and metal coated nanoparticles to induce clustering

    NASA Astrophysics Data System (ADS)

    Gowda, M. H.; Glembocki, O. J.; Geng, S.; Prokes, S. M.; Garces, N.; Caldwell, J. D.

    2010-08-01

    Surface enhanced Raman scattering (SERS) is a powerful technique for the detection of submonolayer coverage of gold or silver surfaces. The magnitude of the effect and the spectral wavelength of the peak depend on the metal nanoparticles used and its geometry. In this paper we show that the use of chemicals that bind to gold or silver can lead to the clustering of nanoparticles. We used well defined Au nanoparticles in our experiments and add cysteamine to solutions containing the nanoparticles. The plasmonic response of the nanoparticles is measured by transmission Surface Plasmon Resonance (SPR) spectroscopy. We observed significant changes to the SPR spectra that are characteristics of close coupled nanoparticles. The time evolution of these changes indicates the formation of gold nanoparticles clusters. The SERS response of these clustered nanoparticles is observed to red shift from the designed peak wavelength in the green to the red. In addition, the placement of these clusters on dielectric surfaces shifts the SPR even more into the red. The experimental results are supported by calculations of the electromagnetic fields using finite difference methods.

  4. Hardening of Metallic Materials Using Plasma Immersion Ion Implantation (PIII)

    NASA Astrophysics Data System (ADS)

    Xu, Yufan; Clark, Mike; Flanagan, Ken; Milhone, Jason; Nonn, Paul; Forest, Cary

    2016-10-01

    A new approach of Plasma Immersion Ion Implantation (PIII) has been developed with the Plasma Couette Experiment Upgrade (PCX-U). The new approach efficiently reduces the duty cycle under the same average power for PIII. The experiment uses a Nitrogen plasma at a relatively high density of 1010 1011 cm-3 with ion temperatures of < 2 eV and electron temperature of 5 10 eV. The pulser for this PIII experiment has a maximum negative bias greater than 20kV, with 60Hz frequency and a 8 μs on-time in one working cycle. The samples (Alloy Steel 9310) are analyzed by a Vicker Hardness Tester to study the hardness and X-ray Photoelectron Spectroscopy (XPS) to study implantation density and depth. Different magnetic fields are also applied on samples to reduce the energy loss and secondary emission. Higher efficiency of implantation is expected from this experiment and the results will be presented. Hilldale Undergraduate/Faculty Research Fellowship of University of Wisconsin-Madison; Professor Cary Forest's Kellett Mid-Career Faculty Award.

  5. Direct Metal Laser Sintering Titanium Dental Implants: A Review of the Current Literature

    PubMed Central

    Mangano, F.; Chambrone, L.; van Noort, R.; Miller, C.; Hatton, P.; Mangano, C.

    2014-01-01

    Statement of Problem. Direct metal laser sintering (DMLS) is a technology that allows fabrication of complex-shaped objects from powder-based materials, according to a three-dimensional (3D) computer model. With DMLS, it is possible to fabricate titanium dental implants with an inherently porous surface, a key property required of implantation devices. Objective. The aim of this review was to evaluate the evidence for the reliability of DMLS titanium dental implants and their clinical and histologic/histomorphometric outcomes, as well as their mechanical properties. Materials and Methods. Electronic database searches were performed. Inclusion criteria were clinical and radiographic studies, histologic/histomorphometric studies in humans and animals, mechanical evaluations, and in vitro cell culture studies on DMLS titanium implants. Meta-analysis could be performed only for randomized controlled trials (RCTs); to evaluate the methodological quality of observational human studies, the Newcastle-Ottawa scale (NOS) was used. Results. Twenty-seven studies were included in this review. No RCTs were found, and meta-analysis could not be performed. The outcomes of observational human studies were assessed using the NOS: these studies showed medium methodological quality. Conclusions. Several studies have demonstrated the potential for the use of DMLS titanium implants. However, further studies that demonstrate the benefits of DMLS implants over conventional implants are needed. PMID:25525434

  6. Silver nanoparticle-enriched diamond-like carbon implant modification as a mammalian cell compatible surface with antimicrobial properties

    PubMed Central

    Gorzelanny, Christian; Kmeth, Ralf; Obermeier, Andreas; Bauer, Alexander T.; Halter, Natalia; Kümpel, Katharina; Schneider, Matthias F.; Wixforth, Achim; Gollwitzer, Hans; Burgkart, Rainer; Stritzker, Bernd; Schneider, Stefan W.

    2016-01-01

    The implant-bone interface is the scene of competition between microorganisms and distinct types of tissue cells. In the past, various strategies have been followed to support bony integration and to prevent bacterial implant-associated infections. In the present study we investigated the biological properties of diamond-like carbon (DLC) surfaces containing silver nanoparticles. DLC is a promising material for the modification of medical implants providing high mechanical and chemical stability and a high degree of biocompatibility. DLC surface modifications with varying silver concentrations were generated on medical-grade titanium discs, using plasma immersion ion implantation-induced densification of silver nanoparticle-containing polyvinylpyrrolidone polymer solutions. Immersion of implants in aqueous liquids resulted in a rapid silver release reducing the growth of surface-bound and planktonic Staphylococcus aureus and Staphylococcus epidermidis. Due to the fast and transient release of silver ions from the modified implants, the surfaces became biocompatible, ensuring growth of mammalian cells. Human endothelial cells retained their cellular differentiation as indicated by the intracellular formation of Weibel-Palade bodies and a high responsiveness towards histamine. Our findings indicate that the integration of silver nanoparticles into DLC prevents bacterial colonization due to a fast initial release of silver ions, facilitating the growth of silver susceptible mammalian cells subsequently. PMID:26955791

  7. Silver nanoparticle-enriched diamond-like carbon implant modification as a mammalian cell compatible surface with antimicrobial properties

    NASA Astrophysics Data System (ADS)

    Gorzelanny, Christian; Kmeth, Ralf; Obermeier, Andreas; Bauer, Alexander T.; Halter, Natalia; Kümpel, Katharina; Schneider, Matthias F.; Wixforth, Achim; Gollwitzer, Hans; Burgkart, Rainer; Stritzker, Bernd; Schneider, Stefan W.

    2016-03-01

    The implant-bone interface is the scene of competition between microorganisms and distinct types of tissue cells. In the past, various strategies have been followed to support bony integration and to prevent bacterial implant-associated infections. In the present study we investigated the biological properties of diamond-like carbon (DLC) surfaces containing silver nanoparticles. DLC is a promising material for the modification of medical implants providing high mechanical and chemical stability and a high degree of biocompatibility. DLC surface modifications with varying silver concentrations were generated on medical-grade titanium discs, using plasma immersion ion implantation-induced densification of silver nanoparticle-containing polyvinylpyrrolidone polymer solutions. Immersion of implants in aqueous liquids resulted in a rapid silver release reducing the growth of surface-bound and planktonic Staphylococcus aureus and Staphylococcus epidermidis. Due to the fast and transient release of silver ions from the modified implants, the surfaces became biocompatible, ensuring growth of mammalian cells. Human endothelial cells retained their cellular differentiation as indicated by the intracellular formation of Weibel-Palade bodies and a high responsiveness towards histamine. Our findings indicate that the integration of silver nanoparticles into DLC prevents bacterial colonization due to a fast initial release of silver ions, facilitating the growth of silver susceptible mammalian cells subsequently.

  8. Investigation of metal hydride nanoparticles templated in metal organic frameworks.

    SciTech Connect

    Jacobs, Benjamin W.; Herberg, Julie L.; Highley, Aaron M.; Grossman, Jeffrey; Wagner, Lucas; Bhakta, Raghu; Peaslee, D.; Allendorf, Mark D.; Liu, X.; Behrens, Richard, Jr.; Majzoub, Eric H.

    2010-11-01

    Hydrogen is proposed as an ideal carrier for storage, transport, and conversion of energy. However, its storage is a key problem in the development of hydrogen economy. Metal hydrides hold promise in effectively storing hydrogen. For this reason, metal hydrides have been the focus of intensive research. The chemical bonds in light metal hydrides are predominantly covalent, polar covalent or ionic. These bonds are often strong, resulting in high thermodynamic stability and low equilibrium hydrogen pressures. In addition, the directionality of the covalent/ionic bonds in these systems leads to large activation barriers for atomic motion, resulting in slow hydrogen sorption kinetics and limited reversibility. One method for enhancing reaction kinetics is to reduce the size of the metal hydrides to nano scale. This method exploits the short diffusion distances and constrained environment that exist in nanoscale hydride materials. In order to reduce the particle size of metal hydrides, mechanical ball milling is widely used. However, microscopic mechanisms responsible for the changes in kinetics resulting from ball milling are still being investigated. The objective of this work is to use metal organic frameworks (MOFs) as templates for the synthesis of nano-scale NaAlH4 particles, to measure the H2 desorption kinetics and thermodynamics, and to determine quantitative differences from corresponding bulk properties. Metal-organic frameworks (MOFs) offer an attractive alternative to traditional scaffolds because their ordered crystalline lattice provides a highly controlled and understandable environment. The present work demonstrates that MOFs are stable hosts for metal hydrides and their reactive precursors and that they can be used as templates to form metal hydride nanoclusters on the scale of their pores (1-2 nm). We find that using the MOF HKUST-1 as template, NaAlH4 nanoclusters as small as 8 formula units can be synthesized inside the pores. A detailed picture of

  9. Silver metal nanoparticles study for biomedical and green house applications

    NASA Astrophysics Data System (ADS)

    Rauwel, E.; Simón-Gracia, L.; Guha, M.; Rauwel, P.; Kuunal, S.; Wragg, D.

    2017-02-01

    Metallic nanoparticles (MNP) with diameters ranging from 2 to 100nm have received extensive attention during the past decades due to their many potential applications. This paper presents a structural and cytotoxicity study of silver metal nanoparticles targeted towards biomedical applications. Spherical Ag MNPs of diameter from 20 to 50 nm have been synthesized. The encapsulation of Ag MNPs inside pH-sensitive polymersomes has been also studied for the development of biomedical applications. A cytotoxicity study of the Ag MNPs against primary prostatic cancer cell line (PPC-1) has demonstrated a high mortality rate for concentrations ranging from 100 to 200mg/L. The paper will discuss the potential for therapeutic treatments of these Ag MNPs.

  10. Lattice plasmons in dielectric nanoparticle arrays arranged on metal film

    NASA Astrophysics Data System (ADS)

    Zhang, Lianxue; Ge, Chaoyang; Zhang, Kun; Tian, Cheng; Fang, Xin; Zhai, Wenhao; Tao, Li; Li, Yanping; Ran, Guangzhao

    2016-12-01

    We propose a hybrid plasmonic photonic crystal consisting of a square array of dielectric nanoparticles arranged on a metal film with a gap inbetween. Simulations show that this plasmonic crystal supports lattice plasmon modes just like the metal nanoparticle array, exhibiting an extremely narrow and deep reflection dip. When interparticle spacing increases from 800 to 1000 nm, the full width at half the maximum of lattice plasmons decreases from 21 to 4 nm, and the lowest reflectance is close to zero. The resonant wavelength of this plasmonic crystal is highly sensitive to the local environment. It yields a sensitivity of 700 nm RIU-1 and a figure of merit of 33, which can be used in sensing of the refractive index.

  11. Tunable Optical Properties of Metal Nanoparticle Sol-Gel Composites

    NASA Technical Reports Server (NTRS)

    Smith, David D.; Snow, Lanee A.; Sibille, Laurent; Ignont, Erica

    2001-01-01

    We demonstrate that the linear and non-linear optical properties of sol-gels containing metal nanoparticles are highly tunable with porosity. Moreover, we extend the technique of immersion spectroscopy to inhomogeneous hosts, such as aerogels, and determine rigorous bounds for the average fractional composition of each component, i.e., the porosity of the aerogel, or equivalently, for these materials, the catalytic dispersion. Sol-gels containing noble metal nanoparticles were fabricated and a significant blue-shift in the surface plasmon resonance (SPR) was observed upon formation of an aerogel, as a result of the decrease in the dielectric constant of the matrix upon supercritical extraction of the solvent. However, as a result of chemical interface damping and aggregation this blue-shift does not strictly obey standard effective medium theories. Mitigation of these complications is achieved by avoiding the use of alcohol and by annealing the samples in a reducing atmosphere.

  12. Optimization of a transferred arc reactor for metal nanoparticle synthesis.

    PubMed

    Stein, Matthias; Kruis, Frank Einar

    The demand for metal nanoparticles is increasing strongly. Transferred arc synthesis is a promising process in this respect, as it shows high production rates, good quality particles and the ability of up-scaling. The influence of several process parameters on the performance of the process in terms of production rate and particle size is investigated. These parameters are the electrode design and adjustment, the gas flow rate and power input. A novel feeding mechanism allows process operation over an extended time period. It is shown that the process is capable of producing pure metal nanoparticles with variable primary particle sizes and comparatively high production rates. Optimal process conditions for a single transferred arc electrode pair are found, which allow further scale-up by numbering up.

  13. Optimization of a transferred arc reactor for metal nanoparticle synthesis

    NASA Astrophysics Data System (ADS)

    Stein, Matthias; Kruis, Frank Einar

    2016-09-01

    The demand for metal nanoparticles is increasing strongly. Transferred arc synthesis is a promising process in this respect, as it shows high production rates, good quality particles and the ability of up-scaling. The influence of several process parameters on the performance of the process in terms of production rate and particle size is investigated. These parameters are the electrode design and adjustment, the gas flow rate and power input. A novel feeding mechanism allows process operation over an extended time period. It is shown that the process is capable of producing pure metal nanoparticles with variable primary particle sizes and comparatively high production rates. Optimal process conditions for a single transferred arc electrode pair are found, which allow further scale-up by numbering up.

  14. Biocidal properties of metal oxide nanoparticles and their halogen adducts

    NASA Astrophysics Data System (ADS)

    Haggstrom, Johanna A.; Klabunde, Kenneth J.; Marchin, George L.

    2010-03-01

    Nanosized metal oxide halogen adducts possess high surface reactivities due to their unique surface morphologies. These adducts have been used as reactive materials against vegetative cells, such as Escherichia coli as well as bacterial endospores, including Bacillus subtilis and Bacillus anthracis (Δ Sterne strain). Here we report high biocidal activities against gram-positive bacteria, gram-negative bacteria, and endospores. The procedure consists of a membrane method. Transmission electron micrographs are used to compare nanoparticle-treated and untreated cells and spores. It is proposed that the abrasive character of the particles, the oxidative power of the halogens/interhalogens, and the electrostatic attraction between the metal oxides and the biological material are responsible for high biocidal activities. While some activity was demonstrated, bacterial endospores were more resistant to nanoparticle treatment than the vegetative bacteria.

  15. Central nervous system toxicity of metallic nanoparticles

    PubMed Central

    Feng, Xiaoli; Chen, Aijie; Zhang, Yanli; Wang, Jianfeng; Shao, Longquan; Wei, Limin

    2015-01-01

    Nanomaterials (NMs) are increasingly used for the therapy, diagnosis, and monitoring of disease- or drug-induced mechanisms in the human biological system. In view of their small size, after certain modifications, NMs have the capacity to bypass or cross the blood–brain barrier. Nanotechnology is particularly advantageous in the field of neurology. Examples may include the utilization of nanoparticle (NP)-based drug carriers to readily cross the blood–brain barrier to treat central nervous system (CNS) diseases, nanoscaffolds for axonal regeneration, nanoelectromechanical systems in neurological operations, and NPs in molecular imaging and CNS imaging. However, NPs can also be potentially hazardous to the CNS in terms of nano-neurotoxicity via several possible mechanisms, such as oxidative stress, autophagy, and lysosome dysfunction, and the activation of certain signaling pathways. In this review, we discuss the dual effect of NMs on the CNS and the mechanisms involved. The limitations of the current research are also discussed. PMID:26170667

  16. Unveiling the chemistry behind the green synthesis of metal nanoparticles.

    PubMed

    Santos, Sónia A O; Pinto, Ricardo J B; Rocha, Sílvia M; Marques, Paula A A P; Pascoal Neto, Carlos; Silvestre, Armando J D; Freire, Carmen S R

    2014-09-01

    Nanobiotechnology has emerged as a fundamental domain in modern science, and metallic nanoparticles (NPs) are one of the largest classes of NPs studied because of their wide spectrum of possible applications in several fields. The use of plant extracts as reducing and stabilizing agents in their synthesis is an interesting and reliable alternative to conventional methodologies. However, the role of the different components of such extracts in the reduction/stabilization of metal ions has not yet been understood clearly. Here we studied the behavior of the main components of a Eucalyptus globulus Labill. bark aqueous extract during metal-ion reduction followed by advanced chromatographic techniques, which allowed us to establish their specific role in the process. The obtained results showed that phenolic compounds, particularly galloyl derivatives, are mainly responsible for the metal-ion reduction, whereas sugars are essentially involved in the stabilization of the NPs.

  17. Serum protein adsorption and excretion pathways of metal nanoparticles

    PubMed Central

    Vinluan, Rodrigo D; Zheng, Jie

    2015-01-01

    While the synthesis of metal nanoparticles (NPs) with fascinating optical and electronic properties have progressed dramatically and their potential biomedical applications were also well demonstrated in the past decade, translation of metal NPs into the clinical practice still remains a challenge due to their severe accumulation in the body. Herein, we give a brief review on size-dependent material properties of metal NPs and their potential biomedical applications, followed by a summary of how structural parameters such as size, shape and charge influence their interactions with serum protein adsorption, cellular uptake and excretion pathways. Finally, the future challenges in minimizing serum protein adsorption and expediting clinical translation of metal NPs were also discussed. PMID:26377047

  18. Metal nanoparticle fluids with magnetically induced electrical switching properties

    NASA Astrophysics Data System (ADS)

    Kim, Younghoon; Cho, Jinhan

    2013-05-01

    We report the successful preparation of solvent-free metal nanoparticle (NP) fluids with multiple-functionalities, such as rheological properties, magnetism, ionic conductivity, and electrical properties, allowing for facile synthesis and mass production. The gold nanoparticles (AuNPs) used in this study were synthesized using tetraoctylammonium bromide (TOABr) in toluene and then directly phase-transferred to solvent-free low-molecular-weight (Mw) imidazolium-type ionic liquid media containing thiol groups (i.e., IL-SH). Magnetic metal fluids (i.e., MIL-SH-AuNPs) were prepared by the addition of FeCl3 powder to metal fluids (i.e., IL-SH-AuNPs). These fluids showed relatively high ionic and electrical conductivities compared with those of conventional metal NP fluids based on organic ILs with high Mw. Furthermore, it was demonstrated that these fluids could be used as electric switches operated using an external magnetic field in organic media.We report the successful preparation of solvent-free metal nanoparticle (NP) fluids with multiple-functionalities, such as rheological properties, magnetism, ionic conductivity, and electrical properties, allowing for facile synthesis and mass production. The gold nanoparticles (AuNPs) used in this study were synthesized using tetraoctylammonium bromide (TOABr) in toluene and then directly phase-transferred to solvent-free low-molecular-weight (Mw) imidazolium-type ionic liquid media containing thiol groups (i.e., IL-SH). Magnetic metal fluids (i.e., MIL-SH-AuNPs) were prepared by the addition of FeCl3 powder to metal fluids (i.e., IL-SH-AuNPs). These fluids showed relatively high ionic and electrical conductivities compared with those of conventional metal NP fluids based on organic ILs with high Mw. Furthermore, it was demonstrated that these fluids could be used as electric switches operated using an external magnetic field in organic media. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr00653k

  19. Metal nanoparticles with sharp corners: Universal properties of plasmon resonances

    NASA Astrophysics Data System (ADS)

    Sturman, B.; Podivilov, E.; Gorkunov, M.

    2013-03-01

    We predict the simultaneous occurrence of two fundamental phenomena for metal nanoparticles possessing sharp corners with variable curvature: First, the main dipolar plasmonic mode experiences a strong red shift with increasing corner curvature; for large values of the curvature, the resonant frequency is controlled by the apex angle of the corner. Second, the split-off plasmonic mode experiences a strong localization at the corners. Altogether, this paves the way for the tailoring of metal nanostructures providing a wavelength-selective excitation of localized plasmons and a strong near-field enhancement of linear and nonlinear optical phenomena.

  20. Rapid laser sintering of metal nano-particles inks

    NASA Astrophysics Data System (ADS)

    Ermak, Oleg; Zenou, Michael; Bernstein Toker, Gil; Ankri, Jonathan; Shacham-Diamand, Yosi; Kotler, Zvi

    2016-09-01

    Fast sintering is of importance in additive metallization processes and especially on sensitive substrates. This work explores the mechanisms which set limits to the laser sintering rate of metal nano-particle inks. A comparison of sintering behavior of three different ink compositions with laser exposure times from micro-seconds to seconds reveals the dominant factor to be the organic content (OC) in the ink. With a low OC silver ink, of 2% only, sintering time falls below 100 μs with resistivity <×4 bulk silver. Still shorter exposure times result in line delamination and deformation with a similar outcome when the OC is increased.

  1. Highly Efficient Transition Metal Nanoparticle Catalysts in Aqueous Solutions.

    PubMed

    Wang, Changlong; Ciganda, Roberto; Salmon, Lionel; Gregurec, Danijela; Irigoyen, Joseba; Moya, Sergio; Ruiz, Jaime; Astruc, Didier

    2016-02-24

    A ligand design is proposed for transition metal nanoparticle (TMNP) catalysts in aqueous solution. Thus, a tris(triazolyl)-polyethylene glycol (tris-trz-PEG) amphiphilic ligand, 2, is used for the synthesis of very small TMNPs with Fe, Co, Ni, Cu, Ru, Pd, Ag, Pt, and Au. These TMNP-2 catalysts were evaluated and compared for the model 4-nitrophenol reduction, and proved to be extremely efficient. High catalytic efficiencies involving the use of only a few ppm metal of PdNPs, RuNPs, and CuNPs were also exemplified in Suzuki-Miyaura, transfer hydrogenation, and click reactions, respectively.

  2. Hydride formation in core-shell alloyed metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Zhdanov, Vladimir P.

    2016-07-01

    The model and analysis presented are focused on hydride formation in nanoparticles with a Pd shell and a core formed by another metal. The arrangement of metal atoms is assumed to be coherent (no dislocations). The lattice strain distribution, elastic energy, and chemical potential of hydrogen atoms are scrutinized. The slope of the chemical potential (as a function of hydrogen uptake) is demonstrated to decrease with increasing the core volume, and accordingly the critical temperature for hydride formation and the corresponding hysteresis loops are predicted to decrease as well.

  3. Light-scattering Characteristics of Metal Nanoparticles on a Single Bacterial Cell.

    PubMed

    Kinoshita, Takamasa; Kiso, Keita; LE, Dung Q; Shiigi, Hiroshi; Nagaoka, Tsutomu

    2016-01-01

    Metal nanoparticles express unique light-scattering characteristics based on the localized surface plasmon resonance, which depends on the metal species, particle size, and aggregation state of the nanoparticles. Therefore, we focused on the light-scattering characteristics of metal nanoparticles, such as silver, gold, and copper oxide, adsorbed on a bacterium. Monodisperse silver nanoparticles expressed the strongest scattered light among them, and showed various colors of scattered light. Although a monodisperse gold nanoparticle produced monochromatic light (green color), the color of the scattered light strongly depended on the aggregation state of the nanoparticles on a bacterium. On the other hand, copper oxide nanoparticles expressed monochromatic light (blue color), regardless of their aggregation states on a bacterium. We examined details concerning the light-scattering characteristics of metal nanoparticles, and discussed the possibility of their applications to bacterial cell imaging.

  4. Dislocation mediated alignment during metal nanoparticle coalescence

    SciTech Connect

    Lange, A. P.; Samanta, A.; Majidi, H.; Mahajan, S.; Ging, J.; Olson, T. Y.; van Benthem, K.; Elhadj, S.

    2016-09-13

    Dislocation mediated alignment processes during gold nanoparticle coalescence were studied at low and high temperatures using molecular dynamics simulations and transmission electron microscopy. Particles underwent rigid body rotations immediately following attachment in both low temperature (500 K) simulated coalescence events and low temperature (~315 K) transmission electron microscopy beam heating experiments. In many low temperature simulations, some degree of misorientation between particles remained after rigid body rotations, which was accommodated by grain boundary dislocation nodes. These dislocations were either sessile and remained at the interface for the duration of the simulation or dissociated and cross-slipped through the adjacent particles, leading to improved co-alignment. Minimal rigid body rotations were observed during or immediately following attachment in high temperature (1100 K) simulations, which is attributed to enhanced diffusion at the particles' interface. However, rotation was eventually induced by {111} slip on planes parallel to the neck groove. These deformation modes led to the formation of single and multi-fold twins whose structures depended on the initial orientation of the particles. The driving force for {111} slip is attributed to high surface stresses near the intersection of low energy {111} facets in the neck region. The details of this twinning process were examined in detail using simulated trajectories, and the results reveal possible mechanisms for the nucleation and propagation of Shockley partials on consecutive planes. Deformation twinning was also observed in-situ using transmission electron microscopy, which resulted in the co-alignment of a set of the particles' {111} planes across their grain boundary and an increase in their dihedral angle. As a result, this constitutes the first detailed experimental observation of deformation twinning during nanoparticle coalescence, validating simulation results

  5. Dislocation mediated alignment during metal nanoparticle coalescence

    DOE PAGES

    Lange, A. P.; Samanta, A.; Majidi, H.; ...

    2016-09-13

    Dislocation mediated alignment processes during gold nanoparticle coalescence were studied at low and high temperatures using molecular dynamics simulations and transmission electron microscopy. Particles underwent rigid body rotations immediately following attachment in both low temperature (500 K) simulated coalescence events and low temperature (~315 K) transmission electron microscopy beam heating experiments. In many low temperature simulations, some degree of misorientation between particles remained after rigid body rotations, which was accommodated by grain boundary dislocation nodes. These dislocations were either sessile and remained at the interface for the duration of the simulation or dissociated and cross-slipped through the adjacent particles, leadingmore » to improved co-alignment. Minimal rigid body rotations were observed during or immediately following attachment in high temperature (1100 K) simulations, which is attributed to enhanced diffusion at the particles' interface. However, rotation was eventually induced by {111} slip on planes parallel to the neck groove. These deformation modes led to the formation of single and multi-fold twins whose structures depended on the initial orientation of the particles. The driving force for {111} slip is attributed to high surface stresses near the intersection of low energy {111} facets in the neck region. The details of this twinning process were examined in detail using simulated trajectories, and the results reveal possible mechanisms for the nucleation and propagation of Shockley partials on consecutive planes. Deformation twinning was also observed in-situ using transmission electron microscopy, which resulted in the co-alignment of a set of the particles' {111} planes across their grain boundary and an increase in their dihedral angle. As a result, this constitutes the first detailed experimental observation of deformation twinning during nanoparticle coalescence, validating simulation results

  6. Wear behaviour of cobalt-chromium-molybdenum alloys used in metal-on-metal hip implants

    NASA Astrophysics Data System (ADS)

    Varano, Rocco

    The influence of carbon (C) content, microstructure, crystallography and mechanical properties on the wear behaviour of metal-on-metal (MM) hip implants made from commercially available cobalt-chromium-molybdenum (CoCrMo) alloys designated as American Society of Testing and Materials (ASTM) grade F1537, F75 and as-cast were studied in this work. The as-received bars of wrought CoCrMo alloys (ASTM F1537 of either about 0.05% or 0.26% C) were each subjected to various heat treatments to develop different microstructures. Pin and plate specimens were fabricated from each bar and were tested against each other using a linear reciprocating pin-on-plate apparatus in 25% by volume bovine serum solution. The applied normal load was 9.81 N and the reciprocating plate had a sinusoidal velocity with an average speed of 26 mm/s. The wear was measured gravimetrically and it was found to be most strongly affected by alloy C content, irrespective of grain size or carbide morphology. More precisely, the wear behaviour was directly correlated to the dissolved C content of the alloys. Increased C in solid-solution coincided with lower volumetric wear since C helps to stabilize the face-centred cubic (FCC) crystal structure thus limiting the amount of strain induced transformation (SIT) to the hexagonal close-packed crystal structure (HCP). Based on the observed surface twinning in and around the contact zone and the potentially detrimental effect of the HCP phase, it was postulated that the MM wear behaviour of CoCrMo alloys in the present study was controlled by a deformation mechanism, rather than corrosion or tribochemical reactions.

  7. Functional Application of Noble Metal Nanoparticles In Situ Synthesized on Ramie Fibers

    NASA Astrophysics Data System (ADS)

    Tang, Bin; Yao, Ya; Li, Jingliang; Qin, Si; Zhu, Haijin; Kaur, Jasjeet; Chen, Wu; Sun, Lu; Wang, Xungai

    2015-09-01

    Different functions were imparted to ramie fibers through treatment with noble metal nanoparticles including silver and gold nanoparticles. The in situ synthesis of silver and gold nanoparticles was achieved by heating in the presence of ramie fibers in the corresponding solutions of precursors. The unique optical property of synthesized noble metal nanoparticles, i.e., localized surface plasmon resonance, endowed ramie fibers with bright colors. Color strength (K/S) of fibers increased with heating temperature. Silver nanoparticles were obtained in alkaline solution, while acidic condition was conducive to gold nanoparticles. The optical properties of treated ramie fibers were investigated using UV-vis absorption spectroscopy. Scanning electron microscopy (SEM) was employed to observe the morphologies of silver and gold nanoparticles in situ synthesized on fibers. The ramie fibers treated with noble metal nanoparticles showed remarkable catalytic activity for reduction of 4-nitrophenol (4-NP) by sodium borohydride. Moreover, the silver nanoparticle treatment showed significant antibacterial property on ramie fibers.

  8. Metal nanoparticles amplify photodynamic effect on skin cells in vitro

    NASA Astrophysics Data System (ADS)

    Bauer, Brigitte; Chen, Si; Käll, Mikael; Gunnarsson, Linda; Ericson, Marica B.

    2011-03-01

    We report on an investigation aimed to increase the efficiency of photodynamic therapy (PDT) through the influence of localized surface plasmon resonances (LSPR's) in metal nanoparticles. PDT is based on photosensitizers that generate singlet oxygen at the tumour site upon exposure to visible light. Although PDT is a well-established treatment for skin cancer, a major drawback is the low quantum yield for singlet-oxygen production. This motivates the development of novel methods that enhance singlet oxygen generation during treatment. In this context, we study the photodynamic effect on cultured human skin cells in the presence or absence of gold nanoparticles with well established LSPR and field-enhancement properties. The cultured skin cells were exposed to protoporphyrin IX and gold nanoparticles and subsequently illuminated with red light. We investigated the differences in cell viability by tuning different parameters, such as incubation time and light dose. In order to find optimal parameters for specific targeting of tumour cells, we compared normal human epidermal keratinocytes with a human squamous skin cancer cell line. The study indicates significantly enhanced cell death in the presence of nanoparticles and important differences in treatment efficiency between normal and tumour cells. These results are thus promising and clearly motivate further development of nanoparticle enhanced clinical PDT treatment.

  9. Radio-frequency capacitance spectroscopy of metallic nanoparticles.

    PubMed

    Frake, James C; Kano, Shinya; Ciccarelli, Chiara; Griffiths, Jonathan; Sakamoto, Masanori; Teranishi, Toshiharu; Majima, Yutaka; Smith, Charles G; Buitelaar, Mark R

    2015-06-04

    Recent years have seen great progress in our understanding of the electronic properties of nanomaterials in which at least one dimension measures less than 100 nm. However, contacting true nanometer scale materials such as individual molecules or nanoparticles remains a challenge as even state-of-the-art nanofabrication techniques such as electron-beam lithography have a resolution of a few nm at best. Here we present a fabrication and measurement technique that allows high sensitivity and high bandwidth readout of discrete quantum states of metallic nanoparticles which does not require nm resolution or precision. This is achieved by coupling the nanoparticles to resonant electrical circuits and measurement of the phase of a reflected radio-frequency signal. This requires only a single tunnel contact to the nanoparticles thus simplifying device fabrication and improving yield and reliability. The technique is demonstrated by measurements on 2.7 nm thiol coated gold nanoparticles which are shown to be in excellent quantitative agreement with theory.

  10. Characterization of interfaces of metal/amorphized (by implantation) Si/c-Si structures

    NASA Astrophysics Data System (ADS)

    Golan, A.; Fastow, R.; Eizenberg, M.

    1990-02-01

    The electrical properties of metal/implanted (amorphous) Si contacts were studied, emphasizing the effects of the doping level, of the metal type, and of the heat treatments applied prior to the metal deposition. The implantation was carried out using 60-keV Ar+ ions at a dose of 1016 cm-2, and resulted in the formation of a thin (1000-Å-thick) amorphous layer on top of the crystalline substrate. The doping level of the implanted Si affected the current-voltage (I-V) characteristics of the contacts mainly in the reverse bias (low doping-low currents), while the forward bias characteristics were quite independent of this parameter. The device characteristics were very sensitive to the metal type, Al, Ti-W, or Pt. Thermal treatments applied prior to the metal deposition affected the characteristics by lowering the device resistance in correspondence with the thinning of the amorphous layer as a result of epitaxial regrowth. The I-V characteristics, as well as their dependence on the different process parameters, are explained using a model of charge injection into a thin layer of trap rich amorphous Si bounded by a metal/a-Si interface on one side and by an a-Si/c-Si heterojunction on the other side.

  11. Comparison of Self-Expanding Polyethylene Terephthalate and Metallic Stents Implanted in Porcine Iliac Arteries

    SciTech Connect

    Wilczek, Krzysztof; Scheerder, Ivan de; Wang Kai; Verbeken, Eric; Piessens, Jan

    1996-05-15

    Purpose: Comparison of the biocompatibility of self-expanding polyethylene terephthalate (PET) stents with self-expanding metallic stents (Wallstents). Methods: Diameter- and length-matched PET stents and Wallstents were symmetrically implanted in the paired iliac arteries of 13 crossbred domestic swine. Stent deployment was studied angiographically and with intravascular ultrasound immediately after stent implantation. The angiographic stented lumen diameter was measured using quantitative vessel analysis before, immediately after stenting, and at 6-week follow-up. Cross-section histopathology and area morphometry were performed. Results: Immediately poststenting, intravascular ultrasound revealed proximal dislocation of 5 of the 13 PET stents, whereas all metal stents were firmly embedded at the implantation site. At 6-week follow-up, three of the remaining PET stents were totally or subtotally occluded by organized thrombus, whereas all metal stents were patent. Compared with immediately poststenting, the angiographic lumen diameter within the five remaining PET stents was reduced by 30%, and that of the metallic stents was virtually unaltered (p < 0.02). This observation was confirmed by postmortem morphometry, wherein the PET-stented vessel segments a diameter stenosis of 40% was measured vs only 9% in the metallic stents (p < 0.0001). Conclusion: PET-stent deployment is difficult to control due to the lack of radiopacity of this stent. PET stents seem to be more thrombogenic and lead to significantly more neointimal proliferation than metallic stents.

  12. Topological design and additive manufacturing of porous metals for bone scaffolds and orthopaedic implants: A review.

    PubMed

    Wang, Xiaojian; Xu, Shanqing; Zhou, Shiwei; Xu, Wei; Leary, Martin; Choong, Peter; Qian, M; Brandt, Milan; Xie, Yi Min

    2016-03-01

    One of the critical issues in orthopaedic regenerative medicine is the design of bone scaffolds and implants that replicate the biomechanical properties of the host bones. Porous metals have found themselves to be suitable candidates for repairing or replacing the damaged bones since their stiffness and porosity can be adjusted on demands. Another advantage of porous metals lies in their open space for the in-growth of bone tissue, hence accelerating the osseointegration process. The fabrication of porous metals has been extensively explored over decades, however only limited controls over the internal architecture can be achieved by the conventional processes. Recent advances in additive manufacturing have provided unprecedented opportunities for producing complex structures to meet the increasing demands for implants with customized mechanical performance. At the same time, topology optimization techniques have been developed to enable the internal architecture of porous metals to be designed to achieve specified mechanical properties at will. Thus implants designed via the topology optimization approach and produced by additive manufacturing are of great interest. This paper reviews the state-of-the-art of topological design and manufacturing processes of various types of porous metals, in particular for titanium alloys, biodegradable metals and shape memory alloys. This review also identifies the limitations of current techniques and addresses the directions for future investigations.

  13. Green nanochemistry: metal oxide nanoparticles and porous thin films from bare metal powders.

    PubMed

    Redel, Engelbert; Petrov, Srebri; Dag, Omer; Moir, Jonathon; Huai, Chen; Mirtchev, Peter; Ozin, Geoffrey A

    2012-01-09

    A universal, simple, robust, widely applicable and cost-effective aqueous process is described for a controlled oxidative dissolution process of micrometer-sized metal powders to form high-purity aqueous dispersions of colloidally stable 3-8 nm metal oxide nanoparticles. Their utilization for making single and multilayer optically transparent high-surface-area nanoporous films is demonstrated. This facile synthesis is anticipated to find numerous applications in materials science, engineering, and nanomedicine.

  14. Optical studies of ion-beam synthesized metal alloy nanoparticles

    SciTech Connect

    Magudapathy, P. Srivatsava, S. K.; Gangopadhyay, P.; Amirthapandian, S.; Sairam, T. N.; Panigrahi, B. K.

    2015-06-24

    Au{sub x}Ag{sub 1-x} alloy nanoparticles with tunable surface plasmon resonance (SPR) have been synthesized on a silica glass substrate. A small Au foil on an Ag foil is irradiated as target substrates such that ion beam falls on both Ag foil and Au foils. Silica slides are kept at an angle ∼45° with respect to the metallic foils. While irradiating the metallic foils with 100 keV Ar{sup +} ions, sputtered Au and Ag atoms get deposited on the silica-glass. In this configuration the foils have been irradiated by Ar{sup +} ions to various fluences at room temperature and the sputtered species are collected on silica slides. Formation of Au{sub x}Ag{sub 1-x} nanoparticles has been confirmed from the optical absorption measurements. With respect to the exposure area of Au and Ag foils to the ion beam, the SPR peak position varies from 450 to 500 nm. Green photoluminescence has been observed from these alloy metal nanoparticles.

  15. Thermoelectric Performance Enhancement by Surrounding Crystalline Semiconductors with Metallic Nanoparticles

    NASA Technical Reports Server (NTRS)

    Kim, Hyun-Jung; King, Glen C.; Park, Yeonjoon; Lee, Kunik; Choi, Sang H.

    2011-01-01

    Direct conversion of thermal energy to electricity by thermoelectric (TE) devices may play a key role in future energy production and utilization. However, relatively poor performance of current TE materials has slowed development of new energy conversion applications. Recent reports have shown that the dimensionless Figure of Merit, ZT, for TE devices can be increased beyond the state-of-the-art level by nanoscale structuring of materials to reduce their thermal conductivity. New morphologically designed TE materials have been fabricated at the NASA Langley Research Center, and their characterization is underway. These newly designed materials are based on semiconductor crystal grains whose surfaces are surrounded by metallic nanoparticles. The nanoscale particles are used to tailor the thermal and electrical conduction properties for TE applications by altering the phonon and electron transport pathways. A sample of bismuth telluride decorated with metallic nanoparticles showed less thermal conductivity and twice the electrical conductivity at room temperature as compared to pure Bi2Te3. Apparently, electrons cross easily between semiconductor crystal grains via the intervening metallic nanoparticle bridges, but phonons are scattered at the interfacing gaps. Hence, if the interfacing gap is larger than the mean free path of the phonon, thermal energy transmission from one grain to others is reduced. Here we describe the design and analysis of these new materials that offer substantial improvements in thermoelectric performance.

  16. Synthesis of nickel nanoparticles supported on metal oxides using electroless plating: controlling the dispersion and size of nickel nanoparticles.

    PubMed

    Wu, Zhijie; Ge, Shaohui; Zhang, Minghui; Li, Wei; Tao, Keyi

    2009-02-15

    Nickel nanoparticles supported on metal oxides were prepared by a modified electroless nickel-plating method. The process and mechanism of electroless plating were studied by changing the active metal (Ag) loading, acidity, and surface area of metal oxides and were characterized by UV-vis spectroscopy, transmission electron microscopy, scanning electron microscopy, and H(2) chemisorption. The results showed that the dispersion of nickel nanoparticles was dependent on the interface reaction between the metal oxide and the plating solution or the active metal and the plating solution. The Ag loading and acidity of the metal oxide mainly affected the interface reaction to change the dispersion of nickel nanoparticles. The use of ultrasonic waves and microwaves and the change of solvents from water to ethylene glycol in the electroless plating could affect the dispersion and size of nickel nanoparticles.

  17. Near-infrared fluorescence imaging platform for quantifying in vivo nanoparticle diffusion from drug loaded implants

    PubMed Central

    Markovic, Stacey; Belz, Jodi; Kumar, Rajiv; Cormack, Robert A; Sridhar, Srinivas; Niedre, Mark

    2016-01-01

    Drug loaded implants are a new, versatile technology platform to deliver a localized payload of drugs for various disease models. One example is the implantable nanoplatform for chemo-radiation therapy where inert brachytherapy spacers are replaced by spacers doped with nanoparticles (NPs) loaded with chemotherapeutics and placed directly at the disease site for long-term localized drug delivery. However, it is difficult to directly validate and optimize the diffusion of these doped NPs in in vivo systems. To better study this drug release and diffusion, we developed a custom macroscopic fluorescence imaging system to visualize and quantify fluorescent NP diffusion from spacers in vivo. To validate the platform, we studied the release of free fluorophores, and 30 nm and 200 nm NPs conjugated with the same fluorophores as a model drug, in agar gel phantoms in vitro and in mice in vivo. Our data verified that the diffusion volume was NP size-dependent in all cases. Our near-infrared imaging system provides a method by which NP diffusion from implantable nanoplatform for chemo-radiation therapy spacers can be systematically optimized (eg, particle size or charge) thereby improving treatment efficacy of the platform. PMID:27069363

  18. Contact mechanics and elastohydrodynamic lubrication in a novel metal-on-metal hip implant with an aspherical bearing surface.

    PubMed

    Meng, Qingen; Gao, Leiming; Liu, Feng; Yang, Peiran; Fisher, John; Jin, Zhongmin

    2010-03-22

    Diameter and diametral clearance of the bearing surfaces of metal-on-metal hip implants and structural supports have been recognised as key factors to reduce the dry contact and hydrodynamic pressures and improve lubrication performance. On the other hand, application of aspherical bearing surfaces can also significantly affect the contact mechanics and lubrication performance by changing the radius of the curvature of a bearing surface and consequently improving the conformity between the head and the cup. In this study, a novel metal-on-metal hip implant employing a specific aspherical bearing surface, Alpharabola, as the acetabular surface was investigated for both contact mechanics and elastohydrodynamic lubrication under steady-state conditions. When compared with conventional spherical bearing surfaces, a more uniform pressure distribution and a thicker lubricant film thickness within the loaded conjunction were predicted for this novel Alpharabola hip implant. The effects of the geometric parameters of this novel acetabular surface on the pressure distribution and lubricant thickness were investigated. A significant increase in the predicted lubricant film thickness and a significant decrease in the dry contact and hydrodynamic pressures were found with appropriate combinations of these geometric parameters, compared with the spherical bearing surface.

  19. Efficient antitumor effect of co-drug-loaded nanoparticles with gelatin hydrogel by local implantation

    PubMed Central

    Zhang, Hao; Tian, Yong; Zhu, Zhenshu; Xu, Huae; Li, Xiaolin; Zheng, Donghui; Sun, Weihao

    2016-01-01

    Tetrandrine (Tet) could enhance the antitumor effect of Paclitaxel (Ptx) by increasing intracellular Reactive Oxygen Species (ROS) levels, which leads to the possibility of co-delivery of both drugs for synergistic antitumor effect. In the current study, we reported an efficient, local therapeutic strategy employing effective Tet and Ptx delivery with a nanoparticle-loaded gelatin system. Tet- and Ptx co-loaded mPEG-PCL nanoparticles (P/T-NPs) were encapsulated into the physically cross-linked gelatin hydrogel and then implanted on the tumor site for continuous drug release. The drug-loaded gelatin hydrogel underwent a phase change when the temperature slowly increased. In vitro study showed that Tet/Ptx-loaded PEG-b-PCL nanoparticles encapsulated within a gelatin hydrogel (P/T-NPs-Gelatin) inhibited the growth and invasive ability of BGC-823 cells more effectively than the combination of free drugs or P/T-NPs. In vivo study validated the therapeutic potential of P/T-NPs-Gelatin. P/T-NPs-Gelatin significantly inhibited the activation of p-Akt and the downstream anti-apoptotic Bcl-2 protein and also inducing the activation of pro-apoptotic Bax protein. Moreover, the molecular-modulating effect of P/T-NPs-Gelatin on related proteins varied slightly under the influence of NAC, which was supported by the observations of the tumor volumes and weights. Based on these findings, local implantation of P/T-NPs-Gelatin may be a promising therapeutic strategy for the treatment of gastric cancer. PMID:27226240

  20. Templated Dry Printing of Conductive Metal Nanoparticles

    NASA Astrophysics Data System (ADS)

    Rolfe, David Alexander

    Printed electronics can lower the cost and increase the ubiquity of electrical components such as batteries, sensors, and telemetry systems. Unfortunately, the advance of printed electronics has been held back by the limited minimum resolution, aspect ratio, and feature fidelity of present printing techniques such as gravure, screen printing and inkjet printing. Templated dry printing offers a solution to these problems by patterning nanoparticle inks into templates before drying. This dissertation shows advancements in two varieties of templated dry nanoprinting. The first, advective micromolding in vapor-permeable templates (AMPT) is a microfluidic approach that uses evaporation-driven mold filling to create submicron features with a 1:1 aspect ratio. We will discuss submicron surface acoustic wave (SAW) resonators made through this process, and the refinement process in the template manufacturing process necessary to make these devices. We also present modeling techniques that can be applied to future AMPT templates. We conclude with a modified templated dry printing that improves throughput and isolated feature patterning by transferring dry-templated features with laser ablation. This method utilizes surface energy-defined templates to pattern features via doctor blade coating. Patterned and dried features can be transferred to a polymer substrate with an Nd:YAG MOPA fiber laser, and printed features can be smaller than the laser beam width.

  1. Peripheral white blood cells profile of biodegradable metal implant in mice animal model

    SciTech Connect

    Paramitha, Devi; Noviana, Deni Estuningsih, Sri; Ulum, Mokhamad Fakhrul; Nasution, Ahmad Kafrawi; Hermawan, Hendra

    2015-09-30

    Biocompatibility or safety of the medical device is considered important. It can be determined by blood profile examination. The aim of this study was to assess the biocompatibility of biodegradable metal implant through peripheral white blood cells (WBCs) profile approach. Forty eight male ddy mice were divided into four groups according to the materials implanted: iron wire (Fe), magnesium rod (Mg), stainless steel surgical wire (SS316L) and control with sham (K). Implants were inserted and attached onto the right femoral bone on latero-medial region. In this study, peripheral white blood cells and leukocyte differentiation were the parameters examined. The result showed that the WBCs value of all groups were decreased at the first day after implantation, increased at the 10th day and continued increasing at the 30th day of observation, except Mg group which has decreased. Neutrophil, as an inflammatory cells, was increased at the early weeks and decreased at the day-30 after surgery in all groups. Despite, these values during the observation were still within the normal range. As a conclus ion, biodegradable metal implants lead to an inflammatory reaction, with no adverse effect on WBC value found.

  2. Peculiarities and application perspectives of metal-ion implants in glasses

    SciTech Connect

    Mazzoldi, P.; Gonella, F.; Arnold, G.W.; Battaglin, G.; Bertoncello, R.

    1993-12-31

    Ion implantation in insulators causes modifications in the refractive-index as a result of radiation damage, phase separation, or compound formation. As a consequence, light waveguides may be formed with interesting applications in the field of optoelectronics. Recently implantation of metals ions (e.g. silver, copper, gold, lead,...) showed the possibility of small radii colloidal particles formation, in a thin surface layer of the glass substrate. These particles exhibit an electron plasmon resonance which depends on the optical constants of the implanted metal and on the refractive-index of the glass host. The non-linear optical properties of such colloids, in particular the enhancement of optical Kerr susceptibility, suggest that the, ion implantation technique may play an important role for the production of all-optical switching devices. In this paper an analysis of the state-of-the-art of the research in this field will be presented in the framework of ion implantation in glass physics and chemistry.

  3. Peripheral white blood cells profile of biodegradable metal implant in mice animal model

    NASA Astrophysics Data System (ADS)

    Paramitha, Devi; Noviana, Deni; Estuningsih, Sri; Ulum, Mokhamad Fakhrul; Nasution, Ahmad Kafrawi; Hermawan, Hendra

    2015-09-01

    Biocompatibility or safety of the medical device is considered important. It can be determined by blood profile examination. The aim of this study was to assess the biocompatibility of biodegradable metal implant through peripheral white blood cells (WBCs) profile approach. Forty eight male ddy mice were divided into four groups according to the materials implanted: iron wire (Fe), magnesium rod (Mg), stainless steel surgical wire (SS316L) and control with sham (K). Implants were inserted and attached onto the right femoral bone on latero-medial region. In this study, peripheral white blood cells and leukocyte differentiation were the parameters examined. The result showed that the WBCs value of all groups were decreased at the first day after implantation, increased at the 10th day and continued increasing at the 30th day of observation, except Mg group which has decreased. Neutrophil, as an inflammatory cells, was increased at the early weeks and decreased at the day-30 after surgery in all groups. Despite, these values during the observation were still within the normal range. As a conclus ion, biodegradable metal implants lead to an inflammatory reaction, with no adverse effect on WBC value found.

  4. Plasma mediated collagen-I-coating of metal implant materials to improve biocompatibility.

    PubMed

    Hauser, Joerg; Koeller, Manfred; Bensch, Sebastian; Halfmann, Helmut; Awakowicz, Peter; Steinau, Hans-Ulrich; Esenwein, Stefan

    2010-07-01

    This study describes the collagen-I coating of titanium and steel implants via cold low-pressure gas plasma treatment. To analyze the coatings in terms of biocompatibility osteoblast-like osteosarcoma cells and human leukocytes were cultivated on the metal surfaces. Two different implant materials were assessed (Ti6Al4V, X2CrNiMo18) and four different surface properties were evaluated: (a) plasma pretreated and collagen-I coated implant materials; (b) collagen-I dip-coated without plasma pretreatment; (c) plasma treated but not collagen-I coated; (d) standard implant materials served as control. The different coating characteristics were analyzed by scanning electron microscopy (SEM). For adhesion and viability tests calcein-AM staining of the cells and Alamar blue assays were performed. The quantitative analysis was conducted by computer assisted microfluorophotography and spectrometer measurements. SEM analysis revealed that stable collagen-I coatings could not be achieved on the dip-coated steel and titanium alloys. Only due to pretreatment with low-pressure gas plasma a robust deposition of collagen I on the surface could be achieved. The cell viability and cell attachment rate on the plasma pretreated, collagen coated surfaces was significantly (p < 0.017) increased compared to the non coated surfaces. Gas plasma treatment is a feasible method for the deposition of proteins on metal implant materials resulting in an improved biocompatibility in vitro. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res, 2010.

  5. Hybrid gas-metal co-implantation with a modified vacuum arc ion source

    SciTech Connect

    Oks, E.M.; Yushkov, G.Y.; Evans, P.J.; Oztarhan, A.; Brown, I.G.; Dickinson, M.R.; Liu, F.; MacGill, R.A.; Monteiro, O.R.; Wang, Z.

    1996-08-01

    Energetic beams of mixed metal and gaseous ion species can be generated with a vacuum arc ion source by adding gas to the arc discharge region. This could be an important tool for ion implantation research by providing a method for forming buried layers of mixed composition such as e.g. metal oxides and nitrides. In work to date, we have formed a number of mixed metal-gas ion beams including Ti+N, Pt+N, Al+O, and Zr+O. The particle current fractions of the metal-gas ion components in the beam ranged from 100% metallic to about 80% gaseous, depending on operational parameters. We have used this new variant of the vacuum arc ion source to carry out some exploratory studies of the effect of Al+O and Zr+O co-implantation on tribology of stainless steel. Here we describe the ion source modifications, species and charge state of the hybrid beams produced, and results of preliminary studies of surface modification of stainless steel by co-implantation of mixed Al/O or Zr/O ion beams. 5 figs, 21 refs.

  6. Gettering of transition metals by cavities in silicon formed by helium ion implantation

    SciTech Connect

    Petersen, G.A.; Myers, S.M.; Follstaedt, D.M.

    1996-09-01

    We have recently completed studies which quantitatively characterize the ability of nanometer-size cavities formed by He ion implantation to getter detrimental metal impurities in Si. Cavity microstructures formed in Si by ion implantation of He and subsequent annealing have been found to capture metal impurities by two mechanisms: (1) chemisorption on internal walls at low concentrations and (2) silicide precipitation at concentrations exceeding the solid solubility. Experiments utilizing ion-beam analysis, cross-sectional transmission electron microscopy, and secondary ion mass spectrometry were performed to quantitatively characterize the gettering effects and to determine the free energies associated with the chemisorbed metal atoms as a function of temperature. Mathematical models utilizing these results have been developed to predict gettering behavior.

  7. Resonances of nanoparticles with poor plasmonic metal tips

    PubMed Central

    Ringe, Emilie; DeSantis, Christopher J.; Collins, Sean M.; Duchamp, Martial; Dunin-Borkowski, Rafal E.; Skrabalak, Sara E.; Midgley, Paul A.

    2015-01-01

    The catalytic and optical properties of metal nanoparticles can be combined to create platforms for light-driven chemical energy storage and enhanced in-situ reaction monitoring. However, the heavily damped plasmon resonances of many catalytically active metals (e.g. Pt, Pd) prevent this dual functionality in pure nanostructures. The addition of catalytic metals at the surface of efficient plasmonic particles thus presents a unique opportunity if the resonances can be conserved after coating. Here, nanometer resolution electron-based techniques (electron energy loss, cathodoluminescence, and energy dispersive X-ray spectroscopy) are used to show that Au particles incorporating a catalytically active but heavily damped metal, Pd, sustain multiple size-dependent localized surface plasmon resonances (LSPRs) that are narrow and strongly localized at the Pd-rich tips. The resonances also couple with a dielectric substrate and other nanoparticles, establishing that the full range of plasmonic behavior is observed in these multifunctional nanostructures despite the presence of Pd. PMID:26617270

  8. First order Raman scattering analysis of transition metal ions implanted GaN

    NASA Astrophysics Data System (ADS)

    Majid, Abdul; Rana, Usman Ali; Shakoor, Abdul; Ahmad, Naeem; Hassan, Najam al; Khan, Salah Ud-Din

    2016-03-01

    Transition Metal (TM) ions V, Cr, Mn and Co were implanted into GaN/sapphire films at fluences 5×1014, 5×1015 and 5×1016 cm-2. First order Raman Scattering (RS) measurements were carried out to study the effects of ion implantation on the microstructure of the materials, which revealed the appearance of disorder and new phonon modes in the lattice. The variations in characteristic modes 1GaN i.e. E2(high) and A1(LO), observed for different implanted samples is discussed in detail. The intensity of nitrogen vacancy related vibrational modes appearing at 363 and 665 cm-1 was observed for samples having different fluences. A gallium vacancy related mode observed at 277/281 cm-1 for TM ions implanted at 5×1014 cm-2 disappeared for all samples implanted with rest of fluences. The fluence dependent production of implantation induced disorder and substitution of TM ions on cationic sites is discussed, which is expected to provide necessary information for the potential use of these materials as diluted magnetic semiconductors in future spintronic devices.

  9. Metallic nanoparticles reduce the migration of human fibroblasts in vitro

    NASA Astrophysics Data System (ADS)

    Vieira, Larissa Fernanda de Araújo; Lins, Marvin Paulo; Viana, Iana Mayane Mendes Nicácio; dos Santos, Jeniffer Estevão; Smaniotto, Salete; Reis, Maria Danielma dos Santos

    2017-03-01

    Nanoparticles have extremely wide applications in the medical and biological fields. They are being used in biosensors, local drug delivery, diagnostics, and medical therapy. However, the potential effects of nanoparticles on target cell and tissue function, apart from cytotoxicity, are not completely understood. Thus, the aim of this study was to investigate the in vitro effects of silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) on human fibroblasts with respect to their interaction with the extracellular matrix and in cell migration. Immunofluorescence analysis revealed that treatment with AgNPs or AuNPs decreased collagen and laminin production at all the concentrations tested (0.1, 1, and 10 μg/mL). Furthermore, cytofluorometric analysis showed that treatment with AgNPs reduced the percentage of cells expressing the collagen receptor very late antigen 2, α2β1 integrin (VLA-2) and the laminin receptor very late antigen 6, α6β1 integrin (VLA-6). In contrast, AuNP treatment increased and decreased the percentages of VLA-2-positive and VLA-6-positive cells, respectively, as compared to the findings for the controls. Analysis of cytoskeletal reorganization showed that treatment with both types of nanoparticles increased the formation of stress fibres and number of cell protrusions and impaired cell polarity. Fibroblasts exposed to different concentrations of AuNPs and AgNPs showed reduced migration through transwell chambers in the functional chemotaxis assay. These results demonstrated that metal nanoparticles may influence fibroblast function by negatively modulating the deposition of extracellular matrix molecules (ECM) and altering the expression of ECM receptors, cytoskeletal reorganization, and cell migration.

  10. Ferroplasmons: Intense Localized Surface Plasmons in Metal-Ferromagnetic Nanoparticles

    SciTech Connect

    Sachan, Ritesh; Malasi, Abhinav; Ge, Jingxuan; Yadavali, Sagar P; Gangopadhyay, Anup; Krishna, Dr. Hare; Garcia, Hernando; Duscher, Gerd J M; Kalyanaraman, Ramki

    2014-01-01

    Interaction of photons with matter at length scales far below their wavelengths has given rise to many novel phenomena, including localized surface plasmon resonance (LSPR). However, LSPR with narrow bandwidth (BW) is observed only in a select few noble metals, and ferromagnets are not among them. Here, we report the discovery of LSPR in ferromagnetic Co and CoFe alloy (8% Fe) in contact with Ag in the form of bimetallic nanoparticles prepared by pulsed laser dewetting. These plasmons in metal-erromagnetic nanostructures, or ferroplasmons (FP) for short, are in the visible spectrum with comparable intensity and BW to those of the LSPRs from the Ag regions. This finding was enabled by electron energy-loss mapping across individual nanoparticles in a monochromated scanning transmission electron microscope. The appearance of the FP is likely due to plasmonic interaction between the contacting Ag and Co nanoparticles. Since there is no previous evidence for materials that simultaneously show ferromagnetism and such intense LSPRs, this discovery may lead to the design of improved plasmonic materials and applications. It also demonstrates that materials with interesting plasmonic properties can be synthesized using bimetallic nanostructures in contact with each other.

  11. Effects of interband transitions on Faraday rotation in metallic nanoparticles.

    PubMed

    Wysin, G M; Chikan, Viktor; Young, Nathan; Dani, Raj Kumar

    2013-08-14

    The Faraday rotation in metallic nanoparticles is considered based on a quantum model for the dielectric function ϵ(ω) in the presence of a DC magnetic field B. We focus on effects in ϵ(ω) due to interband transitions (IBTs), which are important in the blue and ultraviolet for noble metals used in plasmonics. The dielectric function is found using the perturbation of the electron density matrix due to the optical field of the incident electromagnetic radiation. The calculation is applied to transitions between two bands (d and p, for example) separated by a gap, as one finds in gold at the L-point of the Fermi surface. The result of the DC magnetic field is a shift in the effective optical frequency causing IBTs by ±μBB/ħ, where opposite signs are associated with left/right circular polarizations. The Faraday rotation for a dilute solution of 17 nm diameter gold nanoparticles is measured and compared with both the IBT theory and a simpler Drude model for the bound electron response. Effects of the plasmon resonance mode on Faraday rotation in nanoparticles are also discussed.

  12. Nanoparticles reduce nickel allergy by capturing metal ions

    NASA Astrophysics Data System (ADS)

    Vemula, Praveen Kumar; Anderson, R. Rox; Karp, Jeffrey M.

    2011-05-01

    Approximately 10% of the population in the USA suffer from nickel allergy, and many are unable to wear jewellery or handle coins and other objects that contain nickel. Many agents have been developed to reduce the penetration of nickel through skin, but few formulations are safe and effective. Here, we show that applying a thin layer of glycerine emollient containing nanoparticles of either calcium carbonate or calcium phosphate on an isolated piece of pig skin (in vitro) and on the skin of mice (in vivo) prevents the penetration of nickel ions into the skin. The nanoparticles capture nickel ions by cation exchange, and remain on the surface of the skin, allowing them to be removed by simple washing with water. Approximately 11-fold fewer nanoparticles by mass are required to achieve the same efficacy as the chelating agent ethylenediamine tetraacetic acid. Using nanoparticles with diameters smaller than 500 nm in topical creams may be an effective way to limit the exposure to metal ions that can cause skin irritation.

  13. Viral nanoparticles, noble metal decorated viruses and their nanoconjugates.

    PubMed

    Capek, Ignác

    2015-08-01

    Virus-based nanotechnology has generated interest in a number of applications due to the specificity of virus interaction with inorganic and organic nanoparticles. A well-defined structure of virus due to its multifunctional proteinaceous shell (capsid) surrounding genomic material is a promising approach to obtain nanostructured materials. Viruses hold great promise in assembling and interconnecting novel nanosized components, allowing to develop organized nanoparticle assemblies. Due to their size, monodispersity, and variety of chemical groups available for modification, they make a good scaffold for molecular assembly into nanoscale devices. Virus based nanocomposites are useful as an engineering material for the construction of smart nanoobjects because of their ability to associate into desired structures including a number of morphologies. Viruses exhibit the characteristics of an ideal template for the formation of nanoconjugates with noble metal nanoparticles. These bioinspired systems form monodispersed units that are highly amenable through genetic and chemical modifications. As nanoscale assemblies, viruses have sophisticated yet highly ordered structural features, which, in many cases, have been carefully characterized by modern structural biological methods. Plant viruses are increasingly being used for nanobiotechnology purposes because of their relative structural and chemical stability, ease of production, multifunctionality and lack of toxicity and pathogenicity in animals or humans. The multifunctional viruses interact with nanoparticles and other functional additives to the generation of bioconjugates with different properties – possible antiviral and antibacterial activities.

  14. Nanoparticle-induced unusual melting and solidification behaviours of metals

    PubMed Central

    Ma, Chao; Chen, Lianyi; Cao, Chezheng; Li, Xiaochun

    2017-01-01

    Effective control of melting and solidification behaviours of materials is significant for numerous applications. It has been a long-standing challenge to increase the melted zone (MZ) depth while shrinking the heat-affected zone (HAZ) size during local melting and solidification of materials. In this paper, nanoparticle-induced unusual melting and solidification behaviours of metals are reported that effectively solve this long-time dilemma. By introduction of Al2O3 nanoparticles, the MZ depth of Ni is increased by 68%, while the corresponding HAZ size is decreased by 67% in laser melting at a pulse energy of 0.18 mJ. The addition of SiC nanoparticles shows similar results. The discovery of the unusual melting and solidification of materials that contain nanoparticles will not only have impacts on existing melting and solidification manufacturing processes, such as laser welding and additive manufacturing, but also on other applications such as pharmaceutical processing and energy storage. PMID:28098147

  15. Enhancement of the optical transmission by mixing the metallic and dielectric nanoparticles atop the silicon substrate.

    PubMed

    Yeh, Yung-Ming; Wang, Yu-Sheng; Li, Jia-Han

    2011-03-14

    We propose a structure with the metallic and dielectric nanoparticles on the surface of the silicon material and study its optical transmission properties. The structure with the radiuses of the silver and silica nanoparticles as 50 nm and 100 nm, respectively, with the gap as 8 nm between silver and silica nanoparticles is found to have the largest optical transmission into the silicon material in our simulations. The largest field intensities are on the bottom of the silver nanoparticles and these can result strong field scattering into the silicon material. From the plotting of the average power densities around the gaps and the air regions between the silver and silica nanoparticles, the light power can go thorough these regions and flow downward to the silicon material. It is also found that the light energy rotates around the bottom of the silver nanoparticles due to the strong localized surface plasmons. The rectangular arrangement of the nanoparticle structures with mixing metallic and dielectric nanoparticles are studied, and the cases for the structures with only the metallic nanoparticles or only the dielectric nanoparticles are also simulated and compared. The rectangular or hexagonal structures with mixing metallic and dielectric nanoparticles on the surface of the silicon substrate can have better optical transmission than the cases of the rectangular arrangement with only metallic or dielectric nanoparticles.

  16. Osseointegration properties of titanium dental implants modified with a nanostructured coating based on ordered porous silica and bioactive glass nanoparticles

    NASA Astrophysics Data System (ADS)

    Covarrubias, Cristian; Mattmann, Matías; Von Marttens, Alfredo; Caviedes, Pablo; Arriagada, Cristián; Valenzuela, Francisco; Rodríguez, Juan Pablo; Corral, Camila

    2016-02-01

    The fabrication of a nanoporous silica coating loaded with bioactive glass nanoparticles (nBG/NSC) on titanium dental implant surface and its in vitro and in vivo evaluation is presented. The coating was produced by a combined sol-gel and evaporation induced self-assembly process. In vitro bioactivity was assessed in simulated body fluid (SBF) and investigating the osteogenic differentiation of human bone marrow mesenchymal stem cells (hBMSCs). A rat tibial model was employed to analyze the bone response to nBG/NSC-modified titanium implant surface in vivo. The nBG/NSC coating was confirmed at nano level to be constituted by a highly ordered nanoporous silica structure. The coating nanotopography in conjunction with the bioactivity of the BG particles accelerate the in vitro apatite formation and promote the osteogenic differentiation of hBMSCs in absence of osteogenic supplements. These properties accelerate the formation of bone tissue in the periphery of the implant after 3 weeks of implantation. Backscattered scanning electron microscopy images revealed the presence of gaps and soft tissue in the unmodified implant after 6 weeks, whereas the nBG/NSC-modified implant showed mature bone in intimate contact with the implant surface. The nBG/NSC coating appears promising for accelerating the osseointegration of dental implants.

  17. Fabrication of Metal and Metal Oxide Nanoparticles by Algae and their Toxic Effects.

    PubMed

    Siddiqi, Khwaja Salahuddin; Husen, Azamal

    2016-12-01

    Of all the aquatic organisms, algae are a good source of biomolecules. Since algae contain pigments, proteins, carbohydrates, fats, nucleic acids and secondary metabolites such as alkaloids, some aromatic compounds, macrolides, peptides and terpenes, they act as reducing agents to produce nanoparticles from metal salts without producing any toxic by-product. Once the algal biomolecules are identified, the nanoparticles of desired shape or size may be fabricated. The metal and metal oxide nanoparticles thus synthesized have been investigated for their antimicrobial activity against several gram-positive and gram-negative bacterial strains and fungi. Their dimension is controlled by temperature, incubation time, pH and concentration of the solution. In this review, we have attempted to update the procedure of nanoparticle synthesis from algae, their characterization by UV-vis, Fourier transform infrared spectroscopy, transmission electron microscopy, scanning electron microscopy, x-ray diffraction, energy-dispersive x-ray spectroscopy, dynamic light scattering and application in cutting-edge areas.

  18. Fabrication of Metal and Metal Oxide Nanoparticles by Algae and their Toxic Effects

    NASA Astrophysics Data System (ADS)

    Siddiqi, Khwaja Salahuddin; Husen, Azamal

    2016-08-01

    Of all the aquatic organisms, algae are a good source of biomolecules. Since algae contain pigments, proteins, carbohydrates, fats, nucleic acids and secondary metabolites such as alkaloids, some aromatic compounds, macrolides, peptides and terpenes, they act as reducing agents to produce nanoparticles from metal salts without producing any toxic by-product. Once the algal biomolecules are identified, the nanoparticles of desired shape or size may be fabricated. The metal and metal oxide nanoparticles thus synthesized have been investigated for their antimicrobial activity against several gram-positive and gram-negative bacterial strains and fungi. Their dimension is controlled by temperature, incubation time, pH and concentration of the solution. In this review, we have attempted to update the procedure of nanoparticle synthesis from algae, their characterization by UV-vis, Fourier transform infrared spectroscopy, transmission electron microscopy, scanning electron microscopy, x-ray diffraction, energy-dispersive x-ray spectroscopy, dynamic light scattering and application in cutting-edge areas.

  19. Surface Functionalization of Metal Nanoparticles by Conjugated Metal-Ligand Interfacial Bonds: Impacts on Intraparticle Charge Transfer.

    PubMed

    Hu, Peiguang; Chen, Limei; Kang, Xiongwu; Chen, Shaowei

    2016-10-03

    Noble metal nanoparticles represent a unique class of functional nanomaterials with physical and chemical properties that deviate markedly from those of their atomic and bulk forms. In order to stabilize the nanoparticles and further manipulate the materials properties, surface functionalization with organic molecules has been utilized as a powerful tool. Among those, mercapto derivatives have been used extensively as the ligands of choice for nanoparticle surface functionalization by taking advantage of the strong affinity of thiol moieties to transition metal surfaces forming (polar) metal-thiolate linkages. Yet, the nanoparticle material properties are generally discussed within the context of the two structural components, the metal cores and the organic capping layers, whereas the impacts of the metal-sulfur interfacial bonds are largely ignored because of the lack of interesting chemistry. In recent years, it has been found that metal nanoparticles may also be functionalized by stable metal-carbon (or even -nitrogen) covalent bonds. Because of the formation of dπ-pπ interactions between the transition-metal nanoparticles and terminal carbon moieties, the interfacial resistance at the metal-ligand interface is markedly reduced, leading to the emergence of unprecedented optical and electronic properties. In this Account, we summarize recent progress in the studies of metal nanoparticles functionalized by conjugated metal-ligand interfacial bonds that include metal-carbene (M═C) and metal-acetylide (M-C≡)/metal-vinylidene (M═C═C) bonds. Such interfacial bonds are readily formed by ligand self-assembly onto nanoparticle metal cores. The resulting nanoparticles exhibit apparent intraparticle charge delocalization between the particle-bound functional moieties, leading to the emergence of optical and electronic properties that are analogous to those of their dimeric counterparts, as manifested in spectroscopic and electrochemical measurements. This is

  20. Accurate thermoplasmonic simulation of metallic nanoparticles

    NASA Astrophysics Data System (ADS)

    Yu, Da-Miao; Liu, Yan-Nan; Tian, Fa-Lin; Pan, Xiao-Min; Sheng, Xin-Qing

    2017-01-01

    Thermoplasmonics leads to enhanced heat generation due to the localized surface plasmon resonances. The measurement of heat generation is fundamentally a complicated task, which necessitates the development of theoretical simulation techniques. In this paper, an efficient and accurate numerical scheme is proposed for applications with complex metallic nanostructures. Light absorption and temperature increase are, respectively, obtained by solving the volume integral equation (VIE) and the steady-state heat diffusion equation through the method of moments (MoM). Previously, methods based on surface integral equations (SIEs) were utilized to obtain light absorption. However, computing light absorption from the equivalent current is as expensive as O(NsNv), where Ns and Nv, respectively, denote the number of surface and volumetric unknowns. Our approach reduces the cost to O(Nv) by using VIE. The accuracy, efficiency and capability of the proposed scheme are validated by multiple simulations. The simulations show that our proposed method is more efficient than the approach based on SIEs under comparable accuracy, especially for the case where many incidents are of interest. The simulations also indicate that the temperature profile can be tuned by several factors, such as the geometry configuration of array, beam direction, and light wavelength.

  1. Plasmonic transparent conducting metal oxide nanoparticles and nanoparticle films for optical sensing applications

    SciTech Connect

    Ohodnicki, Paul R; Wang, Congjun; Andio, Mark

    2013-07-31

    The ability to monitor gas species selectively, sensitively, and reliably in extreme temperatures and harsh conditions is critically important for more efficient energy production using conventional fossil energy based production technologies, enabling advanced technologies for fossil based power plants of the future, and improving efficiency in domestic manufacturing industries. Optical waveguide based sensing platforms have become increasingly important but a need exists for materials that exhibit useful changes in optical properties in response to changing gas atmospheres at high temperatures. In this manuscript, the onset of a near-IR absorption associated with an increase in free carrier density in doped metal oxide nanoparticles to form so-called conducting metal oxides is discussed in the context of results obtained for undoped and Al-doped ZnO nanoparticle based films. Detailed film characterization results are presented along with measured changes in optical absorption resulting from various high temperature treatments in a range of gas atmospheres. Optical property changes are also discussed in the context of a simple model for optical absorption in conducting metal oxide nanoparticles and thin films. The combination of experimental results and theoretical modeling presented here suggests that such materials have potential for high temperature optical gas sensing applications. Simulated sensing experiments were performed at 500 °C and a useful, rapid, and reproducible near-IR optical sensing response to H{sub 2} confirms that this class of materials shows great promise for optical gas sensing.

  2. Spectral variation of fluorescence lifetime near single metal nanoparticles

    PubMed Central

    Li, Jia; Krasavin, Alexey V.; Webster, Linden; Segovia, Paulina; Zayats, Anatoly V.; Richards, David

    2016-01-01

    We explore the spectral dependence of fluorescence enhancement and the associated lifetime modification of fluorescent molecules coupled to single metal nanoparticles. Fluorescence lifetime imaging microscopy and single-particle dark-field spectroscopy are combined to correlate the dependence of fluorescence lifetime reduction on the spectral overlap between the fluorescence emission and the localised surface plasmon (LSP) spectra of individual gold nanoparticles. A maximum lifetime reduction is observed when the fluorescence and LSP resonances coincide, with good agreement provided by numerical simulations. The explicit comparison between experiment and simulation, that we obtain, offers an insight into the spectral engineering of LSP mediated fluorescence and may lead to optimized application in sensing and biomedicine. PMID:26876780

  3. Surface-mediated light transmission in metal nanoparticle chains

    NASA Astrophysics Data System (ADS)

    Compaijen, P. Jasper; Malyshev, Victor A.; Knoester, Jasper

    2013-05-01

    We study theoretically the efficiency of the transmission of optical signals through a linear chain consisting of identical and equidistantly spaced silver metal nanoparticles. Two situations are compared: the transmission efficiency through an isolated chain and through a chain in close proximity of a reflecting substrate. The Ohmic and radiative losses in each nanoparticle strongly affect the transmission efficiency of an isolated chain and suppress it to large extent. It is shown that the presence of a reflecting interface may enhance the guiding properties of the array. The reason for this is the energy exchange between the surface plasmon polaritons (SPPs) of the array and the substrate. We focus on the dependence of the transmission efficiency on the frequency and polarization of the incoming light, as well as on the influence of the array-interface spacing. Sometimes the effect of these parameters turns out to be counterintuitive, reflecting a complicated interplay of several transmission channels.

  4. Laser induced inverse Landau damping in metallic nanoparticles

    NASA Astrophysics Data System (ADS)

    Garcia, Martin E.; Castro, Alberto; Alonso, J. A.; Rubio, Angel

    2002-03-01

    We perform real space time-dependent density functional calculations to study the response of small metallic nanoparticles to femtosecond laser pulses. In particular, we analyze the role of screening effects for different laser pulse intensities and frequencies. Calculations are performed on sodium clusters using both the Jellium model and pseudopitentials Based on our results we predict that, if a pulse of sufficiently high intensity ( > 10^14 W/cm^2) excites a single-particle state of the nanoparticle, the response of the system involves both the single-particle- and the surface-plasmon states. We argue that this creation of plasmons from the decay of single-particle excitations, which can be viewed as the inverse of the well known Landau-damping effect, is related to the time-evolution of the screening of charge fluctuations.

  5. Few-cycle plasmon oscillations controlling photoemission from metal nanoparticles

    SciTech Connect

    Földi, Péter; Márton, István; Német, Nikolett; Dombi, Péter; Ayadi, Viktor

    2015-01-05

    Few-cycle optical excitation of nanosystems holds promise of fundamental discoveries and applications in ultrafast nanoscience, the development of nanostructured photocathodes, and many more. For these, surface plasmon generation on unprecedented timescales needs to be controlled. For this, few-cycle plasmon oscillations on a metal nanoparticle can be generated by keeping considerable electric field enhancement factors. As an initial application of such a high spatiotemporal localization of an ultrashort laser pulse, we numerically demonstrate the control of photoelectrons on a true sub-fs timescale in nanometric spatial domains. We show that it is only off-resonant nanoparticles that can provide few-cycle plasmons and electron control on this timescale.

  6. Battlefield Acquired Immunogenicity to Metals Affects Orthopedic Implant Outcome

    DTIC Science & Technology

    2013-10-01

    include minor bruising/ hematoma (12.3%), diaphoresis with hypotension (2.6%), syncope (ə%), and cellulitis or phlebitis (ə%). Standard aseptic...PROBLEMS, AND DEVIATIONS Possible adverse events Possible adverse events following phlebotomy include: • Minor bruising/ hematoma (12.3...Lucht U. Metal sensitivity in patients treated for tibial fractures with plates of stainless steel. Acta Orthopedica Scandinavia 1977;48:245-9. Page 11

  7. Radiographically undetectable periprosthetic osteolysis with ASR implants: the implication of blood metal ions.

    PubMed

    Randelli, Filippo; Banci, Lorenzo; Favilla, Sara; Maglione, Daniela; Aliprandi, Alberto

    2013-09-01

    Patients with ASR implants (resurfacing and large-diameter (XL) metal-on-metal (MoM) total hip arthroplasty), even if asymptomatic and with a stable prosthesis, may present extremely high blood metal ion levels. We report on a consecutive series of fourteen ASR revisions, focusing on osteolysis and their radiographic correspondence and their correlation with blood metal ion levels. At revision, seven hips revealed severe periacetabular osteolysis which was radiographically undetectable in six and asymptomatic in five. Seven hips with no acetabular osteolysis had significantly lower serum Cr and Co ion concentrations (respectively 25.2, 41.1 μg/l) compared to the seven hips with severe acetabular bone loss (respectively 70.1, 147.0 μg/l). Elevated blood metal ion levels should be considered as a warning of undetectable and ongoing periprosthetic osteolysis in asymptomatic patients with ASR prosthesis.

  8. Optical scattering from isolated metal nanoparticles and arrays.

    SciTech Connect

    Wurtz, G. A.; Im, J. S.; Gray, S. K.; Wiederrecht, G. P.; Chemistry

    2003-12-25

    Near-field scanning optical microscopy (NSOM) is used to explore the optical scattering from isolated metal nanoparticles (MNPs) and arrays of MNPs. The optical excitation source is an evanescent wave created through total internal reflection of a continuous wave laser beam at the sample-air interface. For optical excitation of isolated Ag and Au MNPs, experimental results show that the scattered light propagates into the far field at an angle of 19{sup o} from the substrate. Finite-difference time-domain (FDTD) calculations are used to study simpler but related metallic nanowire systems under evanescent wave excitation. The FDTD results are found to be similar to the experimental results, indicating the generality of the scattering phenomenon. NSOM characterization of plasmonic arrays that consist of closely spaced Ag MNPs are subsequently reported. Confined optical signals within the array are observed along with a reduction in the far-field scattered signal. Simultaneous collection of the atomic force microscopy signal and near-field signals also shows that the spatial distribution of the near-field is strongly modified in the arrays compared to isolated MNPs. FDTD studies on arrays of nanowires also show large differences from the isolated metal nanoparticle calculations, including a decrease in the forward scattered angle (with chain length) and diminished overall forward scattering.

  9. Effect of metal nanoparticles decoration on electron field emission property of graphene sheets.

    PubMed

    Baby, Tessy Theres; Ramaprabhu, Sundara

    2011-10-05

    The electron field emission from metal nanoparticle decorated hydrogen exfoliated graphene (metal/HEG) occurs at low turn on and threshold fields due to its low work function and high field enhancement factor.

  10. The two faces of metal ions: From implants rejection to tissue repair/regeneration.

    PubMed

    Vasconcelos, Daniel M; Santos, Susana G; Lamghari, Meriem; Barbosa, Mário A

    2016-04-01

    The paradigm of metallic ions as exclusive toxic agents is changing. During the last 60 years, knowledge about toxicological and immunological reactions to metal particles and ions has advanced considerably. Hip prostheses, namely metal-on-metal bearings, have prompted studies about excessive and prolonged exposure to prosthetic debris. In that context, the interactions of metal particles and ions with cells and tissues are mostly harmful, inducing immune responses that lead to osteolysis and implant failure. However, in the last decade, new strategies to promote immunomodulation and healing have emerged based on the unique properties of metallic ions. The atom-size and charge enable ions to interact with key macromolecules (e.g. proteins, nucleic acids) that affect cellular function. Moreover, these agents are inexpensive, stable and can be integrated in biomaterials, which may open new avenues for a novel generation of medical devices. Herein, orthopedic devices are discussed as models for adverse responses to metal ions, and debated together with the potential to use metal ions-based therapies, thus bridging the gap between unmet clinical needs and cutting-edge research. In summary, this review addresses the two "faces" of metallic ions, from pathological responses to innovative research strategies that use metal ions for regenerative medicine.

  11. Present status and future outlook of selective metallization for electronics industry by laser irradiation to metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Watanabe, Akira

    2015-03-01

    Recently an alternative to conventional methods based on vacuum processes such as evaporation or sputtering is desired to reduce the energy consumption and the environmental impact. Printed electronics has been developed as a one of the candidates, which is based on wet processes using soluble functional materials such as organic semiconductors, inorganic nanomaterials, organic-inorganic hybrids, and so on. Although inkjet printing has been studied widely as a core technology of printed electronics, the limitation of resolution is around 20 micrometer. The combination of the inkjet printing with other selective metallization process is necessary because the resolution of several micrometers is required in some optical and electrical devices. The laser processing has emerged as an attractive technique in microelectronics because of the fascinating features such as high resolution, high degree of flexibility to control the resolution and size of the micro-patterns, high speed, and a little environmental pollution. In this paper, the present status and future outlook of selective metallization for interconnection and the formation of transparent conductive film based on the laser processing using metal nanoparticles were reported. The laser beam irradiation to metal nanoparticles causes the fast and efficient sintering by plasmon resonance of metal nanoparticle, where the absorbed energy is confined in a nanoparticle and the nanoparticle acts as a nano-heater. The laser irradiation to metal nanoparticles was applied to the laser direct writing of metal wiring and micropatterns using silver and copper nanoparticles.

  12. Osseointegration and biocompatibility of different metal implants - a comparative experimental investigation in sheep

    PubMed Central

    2012-01-01

    Background In the present study, 4 different metallic implant materials, either partly coated or polished, were tested for their osseointegration and biocompatibility in a pelvic implantation model in sheep. Methods Materials to be evaluated were: Cobalt-Chrome (CC), Cobalt-Chrome/Titanium coating (CCTC), Cobalt-Chrome/Zirconium/Titanium coating (CCZTC), Pure Titanium Standard (PTST), Steel, TAN Standard (TANST) and TAN new finish (TANNEW). Surgery was performed on 7 sheep, with 18 implants per sheep, for a total of 63 implants. After 8 weeks, the specimens were harvested and evaluated macroscopically, radiologically, biomechanically (removal torque), histomorphometrically and histologically. Results Cobalt-Chrome screws showed significantly (p = 0.031) lower removal torque values than pure titanium screws and also a tendency towards lower values compared to the other materials, except for steel. Steel screws showed no significant differences, in comparison to cobalt-chrome and TANST, however also a trend towards lower torque values than the remaining materials. The results of the fluorescence sections agreed with those of the biomechanical test. Histomorphometrically, there were no significant differences of bone area between the groups. The BIC (bone-to-implant-contact), used for the assessment of the osseointegration, was significantly lower for cobalt-chrome, compared to steel (p = 0.001). Steel again showed a lower ratio (p = 0.0001) compared to the other materials. Conclusion This study demonstrated that cobalt-chrome and steel show less osseointegration than the other metals and metal-alloys. However, osseointegration of cobalt-chrome was improved by zirconium and/or titanium based coatings (CCTC, TANST, TAN, TANNEW) being similar as pure titanium in their osseointegrative behavior. PMID:22400715

  13. Formation of Ge nanoparticles in SiO{sub x}N{sub y} by ion implantation and thermal annealing

    SciTech Connect

    Mirzaei, S. Kremer, F.; Feng, R.; Ridgway, M. C.; Sprouster, D. J.; Araujo, L. L.; Glover, C. J.

    2015-10-21

    Germanium nanoparticles embedded within dielectric matrices hold much promise for applications in optoelectronic and electronic devices. Here we investigate the formation of Ge nanoparticles in amorphous SiO{sub 1.67}N{sub 0.14} as a function of implanted atom concentration and thermal annealing temperature. Using x-ray absorption spectroscopy and other complementary techniques, we show Ge nanoparticles exhibit significant finite-size effects such that the coordination number decreases and structural disorder increases as the nanoparticle size decreases. While the composition of SiO{sub 1.67}N{sub 0.14} is close to that of SiO{sub 2}, we demonstrate that the addition of this small fraction of N yields a much reduced nanoparticle size relative to those formed in SiO{sub 2} under comparable implantation and annealing conditions. We attribute this difference to an increase in an atomic density and a much reduced diffusivity of Ge in the oxynitride matrix. These results demonstrate the potential for tailoring Ge nanoparticle sizes and structural properties in the SiO{sub x}N{sub y} matrices by controlling the oxynitride stoichiometry.

  14. Preventing bacterial growth on implanted device with an interfacial metallic film and penetrating X-rays.

    PubMed

    An, Jincui; Sun, An; Qiao, Yong; Zhang, Peipei; Su, Ming

    2015-02-01

    Device-related infections have been a big problem for a long time. This paper describes a new method to inhibit bacterial growth on implanted device with tissue-penetrating X-ray radiation, where a thin metallic film deposited on the device is used as a radio-sensitizing film for bacterial inhibition. At a given dose of X-ray, the bacterial viability decreases as the thickness of metal film (bismuth) increases. The bacterial viability decreases with X-ray dose increases. At X-ray dose of 2.5 Gy, 98% of bacteria on 10 nm thick bismuth film are killed; while it is only 25% of bacteria are killed on the bare petri dish. The same dose of X-ray kills 8% fibroblast cells that are within a short distance from bismuth film (4 mm). These results suggest that penetrating X-rays can kill bacteria on bismuth thin film deposited on surface of implant device efficiently.

  15. Quality assurance: recommended guidelines for safe heating by capacitive-type heating technique to treat patients with metallic implants.

    PubMed

    Kato, Hirokazu; Kondo, Motoharu; Imada, Hajime; Kuroda, Masahiro; Kamimura, Yoshitsugu; Saito, Kazuyuki; Kuroda, Kagayaki; Ito, Koichi; Takahashi, Hideaki; Matsuki, Hidetoshi

    2013-05-01

    This article is a redissemination of the previous Japanese Quality Assurance Guide guidelines. Specific absorption rate and temperature distribution were investigated with respect to various aspects including metallic implant size and shape, insertion site, insertion direction, blood flow and heating power, and simulated results were compared with adverse reactions of patients treated by radio frequency capacitive-type heating. Recommended guidelines for safe heating methods for patients with metallic implants are presented based on our findings.

  16. Metal phytoremediation: General strategies, genetically modified plants and applications in metal nanoparticle contamination.

    PubMed

    Gomes, Maria Angélica da Conceição; Hauser-Davis, Rachel Ann; de Souza, Adriane Nunes; Vitória, Angela Pierre

    2016-12-01

    The accumulation of metals in different environmental compartments poses a risk to both the environment and biota health. In particular, the continuous increase of these elements in soil ecosystems is a major worldwide concern. Phytoremediation has been gaining more attention in this regard. This approach takes advantage of the unique and selective uptake capabilities of plant root systems, and applies these natural processes alongside the translocation, bioaccumulation, and contaminant degradation abilities of the entire plant and, although it is a relatively recent technology, beginning in the 90's, it is already considered a green alternative solution to the problem of metal pollution, with great potential. This review focuses on phytoremediation of metals from soil, sludge, wastewater and water, the different strategies applied, the biological and physico-chemical processes involved and the advantages and limitations of each strategy. Special note is given to the use of transgenic species and phytoremediation of metallic nanoparticles.

  17. Antibacterial properties of metal and metalloid ions in chronic periodontitis and peri-implantitis therapy.

    PubMed

    Goudouri, Ourania-Menti; Kontonasaki, Eleana; Lohbauer, Ulrich; Boccaccini, Aldo R

    2014-08-01

    Periodontal diseases like periodontitis and peri-implantitis have been linked with Gram-negative anaerobes. The incorporation of various chemotherapeutic agents, including metal ions, into several materials and devices has been extensively studied against periodontal bacteria, and materials doped with metal ions have been proposed for the treatment of periodontal and peri-implant diseases. The aim of this review is to discuss the effectiveness of materials doped with metal and metalloid ions already used in the treatment of periodontal diseases, as well as the potential use of alternative materials that are currently available for other applications but have been proved to be cytotoxic to the specific periodontal pathogens. The sources of this review included English articles using Google Scholar™, ScienceDirect, Scopus and PubMed. Search terms included the combinations of the descriptors "disease", "ionic species" and "bacterium". Articles that discuss the biocidal properties of materials doped with metal and metalloid ions against the specific periodontal bacteria were included. The articles were independently extracted by two authors using predefined data fields. The evaluation of resources was based on the quality of the content and the relevance to the topic, which was evaluated by the ionic species and the bacteria used in the study, while the final application was not considered as relevant. The present review summarizes the extensive previous and current research efforts concerning the use of metal ions in periodontal diseases therapy, while it points out the challenges and opportunities lying ahead.

  18. Topological collective plasmons in bipartite chains of metallic nanoparticles

    NASA Astrophysics Data System (ADS)

    Downing, Charles A.; Weick, Guillaume

    2017-03-01

    We study a bipartite linear chain constituted by spherical metallic nanoparticles, where each nanoparticle supports a localized surface plasmon. The near-field dipolar interaction between the localized surface plasmons gives rise to collective plasmons, which are extended over the whole nanoparticle array. We derive analytically the spectrum and the eigenstates of the collective plasmonic excitations. At the edge of the Brillouin zone, the spectrum is of a pseudorelativistic nature similar to that present in the electronic band structure of polyacetylene. We find the effective Dirac Hamiltonian for the collective plasmons and show that the corresponding spinor eigenstates represent one-dimensional Dirac-like massive bosonic excitations. Therefore, the plasmonic lattice exhibits similar effects to those found for electrons in one-dimensional Dirac materials, such as the ability for transmission with highly suppressed backscattering due to Klein tunneling. We also show that the system is governed by a nontrivial Zak phase, which predicts the manifestation of edge states in the chain. When two dimerized chains with different topological phases are connected, we find the appearance of the bosonic version of a Jackiw-Rebbi midgap state. We further investigate the radiative and nonradiative lifetimes of the collective plasmonic excitations and comment on the challenges for experimental realization of the topological effects found theoretically.

  19. Selective Catalysis in Nanoparticle Metal-Organic Framework Composites

    NASA Astrophysics Data System (ADS)

    Stephenson, Casey Justin

    The design of highly selective catalysts are becoming increasingly important, especially as chemical and pharmaceutical industries seek to improve atom economy and minimize energy intensive separations that are often required to separate side products from the desired product. Enzymes are among the most selective of all catalysts, generally operating through molecular recognition whereby an active site analogous to a lock and the substrate is analogous to a key. The assembly of a porous, crystalline material around a catalytically active metal particle could serve as an artificial enzyme. In this vein, we first synthesized the polyvinylpyrrolidone (PVP) coated nanoparticles of interest and then encapsulated them within zeolitic imidazolate framework 8 or ZIF-8. 2.8 nm Pt-PVP nanoparticles, which were encapsulated within ZIF-8 to form Pt ZIF-8 composite. Pt ZIF-8 was inactive for the hydrogenation of cyclic olefins such as cis-cyclooctene and cis-cyclohexene while the composite proved to be a highly selective catalyst for the hydrogenation of terminal olefins, hydrogenating trans-1,3-hexadiene to 3-hexene in 95% selectivity after 24 hours under 1 bar H2. We extended our encapsulation method to sub-2 nm Au nanoparticles to form Au ZIF-8. Au ZIF-8 served as a highly chemoselective catalyst for the hydrogenation of crotonaldehyde an alpha,beta-unsaturated aldehyde, to crotyl alcohol an alpha,beta-unsaturated alcohol, in 90-95% selectivity. In order to investigate nanoparticle size effects on selectivity, 6-10 nm Au nanoparticles were encapsulated within ZIF-8 to form Au6 ZIF-8. Control catalysts with nanoparticles supported on the surface of ZIF-8 were synthesized as well, Au/ZIF-8 and Au6/ZIF-8. Au6 ZIF-8 hydrogenated crotonaldehyde in 85% selectivity towards the unsaturated alcohol. Catalysts with nanoparticles supported on the exterior of ZIF-8 were far less selective towards the unsaturated alcohol. Post-catalysis transmission electron microscopy analysis of Au ZIF

  20. Bone Loss at Implant with Titanium Abutments Coated by Soda Lime Glass Containing Silver Nanoparticles: A Histological Study in the Dog

    PubMed Central

    Martinez, Arturo; Guitián, Francisco; López-Píriz, Roberto; Bartolomé, José F.; Cabal, Belén; Esteban-Tejeda, Leticia; Torrecillas, Ramón; Moya, José S.

    2014-01-01

    The aim of the present study was to evaluate bone loss at implants connected to abutments coated with a soda-lime glass containing silver nanoparticles, subjected to experimental peri-implantitis. Also the aging and erosion of the coating in mouth was studied. Five beagle dogs were used in the experiments. Three implants were placed in each mandible quadrant: in 2 of them, Glass/n-Ag coated abutments were connected to implant platform, 1 was covered with a Ti-mechanized abutment. Experimental peri-implantitis was induced in all implants after the submarginal placement of cotton ligatures, and three months after animals were euthanatized. Thickness and morphology of coating was studied in abutment cross-sections by SEM. Histology and histo-morphometric studies were carried on in undecalfied ground slides. After the induced peri-implantitis: 1.The abutment coating shown losing of thickness and cracking. 2. The histometry showed a significant less bone loss in the implants with glass/n-Ag coated abutments. A more symmetric cone of bone resorption was observed in the coated group. There were no significant differences in the peri-implantitis histological characteristics between both groups of implants. Within the limits of this in-vivo study, it could be affirmed that abutments coated with biocide soda-lime-glass-silver nanoparticles can reduce bone loss in experimental peri-implantitis. This achievement makes this coating a suggestive material to control peri-implantitis development and progression. PMID:24466292

  1. Doping of Metal-Organic Frameworks with Functional Guest Molecules and Nanoparticles

    NASA Astrophysics Data System (ADS)

    Schröder, Felicitas; Fischer, Roland A.

    Nanoparticle synthesis within metal-organic frameworks (MOFs) is performed by the adsorption of suitable precursor molecules for the metal component and subsequent decomposition to the composite materials nanoparticles@MOF. This chapter will review different approaches of loading MOFs with more complex organic molecules and metal-organic precursor molecules. The related reactions inside MOFs are discussed with a focus on stabilizing reactive intermediates in the corresponding cavities. The syntheses of metal and metal oxide nanoparticles inside MOFs are reviewed, and different synthetic routes compared. Emphasis is placed on the micro structural characterization of the materials nanoparticles@MOF with a particular focus on the location of embedded nanoparticles using TEM methods. Some first examples of applications of the doped MOFs in heterogeneous catalysis and hydrogen storage are described.

  2. Plasmonics: Heat transfer between metal nanoparticles and supporting nanolayers

    NASA Astrophysics Data System (ADS)

    Zhdanov, Vladimir P.; Zorić, Igor; Kasemo, Bengt

    2012-09-01

    Due to plasmon-related local field enhancement, metal nanoparticles can be used in conventional surface photochemistry and also in numerous applications, e.g., for optimization of the performance of thin film solar cells and photo-electrochemical cells employed for solar-to-fuel energy conversion. In the experimental model studies related to such cells, metal nanoparticles are located on or embedded into a 40-100 nm thick active photoabsorbing material (e.g., Si or Fe2O3), supported underneath by a ∼1 mm thick glass layer. We present general equations describing heat transport in the layered systems of this type. The equations contain the coefficients of heat transfer between different nanophases. Using the Debye model, we derive an analytical expression for these coefficients. Our calculations show that for the energy flux corresponding to solar light the overheating is practically negligible. In more conventional surface photochemistry, the effect may be more appreciable with increasing the energy flux and support thickness.

  3. Multiple percolation tunneling staircase in metal-semiconductor nanoparticle composites

    SciTech Connect

    Mukherjee, Rupam; Huang, Zhi-Feng; Nadgorny, Boris

    2014-10-27

    Multiple percolation transitions are observed in a binary system of RuO{sub 2}-CaCu{sub 3}Ti{sub 4}O{sub 12} metal-semiconductor nanoparticle composites near percolation thresholds. Apart from a classical percolation transition, associated with the appearance of a continuous conductance path through RuO{sub 2} metal oxide nanoparticles, at least two additional tunneling percolation transitions are detected in this composite system. Such behavior is consistent with the recently emerged picture of a quantum conductivity staircase, which predicts several percolation tunneling thresholds in a system with a hierarchy of local tunneling conductance, due to various degrees of proximity of adjacent conducting particles distributed in an insulating matrix. Here, we investigate a different type of percolation tunneling staircase, associated with a more complex conductive and insulating particle microstructure of two types of non-spherical constituents. As tunneling is strongly temperature dependent, we use variable temperature measurements to emphasize the hierarchical nature of consecutive tunneling transitions. The critical exponents corresponding to specific tunneling percolation thresholds are found to be nonuniversal and temperature dependent.

  4. Using the "final-on-four" concept to deliver an immediate metal-resin implant-fixed complete dental prosthesis.

    PubMed

    Yilmaz, Burak; Ozcelik, Tuncer Burak; McGlumphy, Edwin

    2015-08-01

    In traditional dental implant therapy, the time between implant placement and delivery of the definitive prosthesis can be long and uncomfortable for a patient wearing a conventional removable denture on an atrophied ridge. New clinical protocols, often with tilted implants, are being used to immediately restore mandibular implants with interim restorations, thus shortening the patient's return to function. However, these conversion type interim restorations do not decrease the time to definitive prosthetic rehabilitation. The Ohio State University (OSU) developed an immediate load surgical and prosthetic protocol to compensate for the disadvantages of previous techniques. With this protocol, a custom, definitive, screw-retained metal-resin fixed prosthesis can be delivered 2 to 4 days postoperatively and has been described using 5 implants. This clinical report presents the OSU immediate loading protocol, combined with a tilted implant technique, for the fabrication of a mandibular metal-resin implant fixed complete dental prosthesis (MRIFCDP) in 3 days postoperatively and with only 4 implants. Replacing the mandibular dentition with an immediate load-fixed metal-resin prosthesis by means of the "final-on-four" technique resulted in a custom, definitive, and functional restorative solution immediately after surgery.

  5. Greener syntheses of metallic nanoparticles and zinc oxide nanopowders

    NASA Astrophysics Data System (ADS)

    Samson, Jacopo

    In recent years, nanotechnology and nanomaterials synthesis have attracted a great deal of attention in the scientific community. Nanomaterials display size and morphology-related optical properties that differ from their bulk counterparts and therefore can be used for many applications in different fields such as biomedicine, electronics, antibacterial agents, and energy. Attempts to fabricate different morphologies of metallic and metal oxide nanoparticles (NPs) have successfully yielded attractive nanostructures such as particles, rods, helices, combs, tetra-pods, and flowers, all displaying properties mainly related to their enhanced surface area and/or aspect ratios. Most of the above mentioned nanomaterials productions have employed harsh synthetic routes such as high temperatures, low pressures, and the use of costly equipments. Here we show how a greener approach to nanomaterials synthesis is feasible with both minimization of aqueous precursors, energy and employment of a multi-block heater for temperature control. We present in this thesis several methods for the preparation of NPs of several materials that focus on minimizing the environmental impact of the synthesis itself. First, we describe the use of the toroidal form of plasmid DNA as a rigid narrowly dispersed bio-polymeric nanocavity, which mold the formation of disc-shaped nanoparticles of several types of metals. This approach exploits several properties of plasmid DNA: (a) DNA affinity for metal cations, (b) toroidal plasmid DNA structures which are favored by metal ionic binding, and (c) the ability to vary plasmid size. Herein, we present a complementary synthetic method based on a kinetic approach wherein the plasmid DNA acts as a template to initiate and control the formation of Au and other metallic NPs by incubation at elevated temperatures. Also reported herein is a simple, scalable hydrothermal method to make ZnO NPs that exploits temperature to precisely control the range of pH values

  6. Synthesis of ternary metal nitride nanoparticles using mesoporous carbon nitride as reactive template.

    PubMed

    Fischer, Anna; Müller, Jens Oliver; Antonietti, Markus; Thomas, Arne

    2008-12-23

    Mesoporous graphitic carbon nitride was used as both a nanoreactor and a reactant for the synthesis of ternary metal nitride nanoparticles. By infiltration of a mixture of two metal precursors into mesoporous carbon nitride, the pores act first as a nanoconfinement, generating amorphous mixed oxide nanoparticles. During heating and decomposition, the carbon nitride second acts as reactant or, more precisely, as a nitrogen source, which converts the preformed mixed oxide nanoparticles into the corresponding nitride (reactive templating). Using this approach, ternary metal nitride particles with diameters smaller 10 nm composed of aluminum gallium nitride (Al-Ga-N) and titanium vanadium nitride (Ti-V-N) were synthesized. Due to the confinement effect of the carbon nitride matrix, the composition of the resulting metal nitride can be easily adjusted by changing the concentration of the preceding precursor solution. Thus, ternary metal nitride nanoparticles with continuously adjustable metal composition can be produced.

  7. Metallic Nickel Nanoparticles May Exhibit Higher Carcinogenic Potential than Fine Particles in JB6 Cells

    PubMed Central

    Bowman, Linda; Zou, Baobo; Mao, Guochuan; Xu, Jin; Castranova, Vincent; Zhao, Jinshun; Ding, Min

    2014-01-01

    While numerous studies have described the pathogenic and carcinogenic effects of nickel compounds, little has been done on the biological effects of metallic nickel. Moreover, the carcinogenetic potential of metallic nickel nanoparticles is unknown. Activator protein-1 (AP-1) and nuclear factor-κB (NF-κB) have been shown to play pivotal roles in tumor initiation, promotion, and progression. Mutation of the p53 tumor suppressor gene is considered to be one of the steps leading to the neoplastic state. The present study examines effects of metallic nickel fine and nanoparticles on tumor promoter or suppressor gene expressions as well as on cell transformation in JB6 cells. Our results demonstrate that metallic nickel nanoparticles caused higher activation of AP-1 and NF-κB, and a greater decrease of p53 transcription activity than fine particles. Western blot indicates that metallic nickel nanoparticles induced a higher level of protein expressions for R-Ras, c-myc, C-Jun, p65, and p50 in a time-dependent manner. In addition, both metallic nickel nano- and fine particles increased anchorage-independent colony formation in JB6 P+ cells in the soft agar assay. These results imply that metallic nickel fine and nanoparticles are both carcinogenetic in vitro in JB6 cells. Moreover, metallic nickel nanoparticles may exhibit higher carcinogenic potential, which suggests that precautionary measures should be taken in the use of nickel nanoparticles or its compounds in nanomedicine. PMID:24691273

  8. Dose perturbation in the presence of metallic implants: treatment planning system versus Monte Carlo simulations

    NASA Astrophysics Data System (ADS)

    Wieslander, Elinore; Knöös, Tommy

    2003-10-01

    An increasing number of patients receiving radiation therapy have metallic implants such as hip prostheses. Therefore, beams are normally set up to avoid irradiation through the implant; however, this cannot always be accomplished. In such situations, knowledge of the accuracy of the used treatment planning system (TPS) is required. Two algorithms, the pencil beam (PB) and the collapsed cone (CC), are implemented in the studied TPS. Comparisons are made with Monte Carlo simulations for 6 and 18 MV. The studied materials are steel, CoCrMo, Orthinox® (a stainless steel alloy and registered trademark of Stryker Corporation), TiAlV and Ti. Monte Carlo simulated depth dose curves and dose profiles are compared to CC and PB calculated data. The CC algorithm shows overall a better agreement with Monte Carlo than the PB algorithm. Thus, it is recommended to use the CC algorithm to get the most accurate dose calculation both for the planning target volume and for tissues adjacent to the implants when beams are set up to pass through implants.

  9. Synthesis of low-melting-point metallic nanoparticles with an ultrasonic nanoemulsion method.

    PubMed

    Han, Z H; Yang, B; Qi, Y; Cumings, J

    2011-05-01

    A one-step, economical nanoemulsion method has been introduced to synthesize low-melting-point metallic nanoparticles. This nanoemulsion technique exploits the extremely high shear rates generated by the ultrasonic agitation and the relatively large viscosity of the continuous phase - polyalphaolefin (PAO), to rupture the molten metal down to diameter below 100 nm. Field's metal nanoparticles and Indium nanoparticles of respective average diameters of 15 nm and 30 nm have been obtained. The nanoparticles size and shape are determined by transmission electron microscopy (TEM). Their phase transition behavior is examined using a differential scanning calorimeter (DSC). It is found that these nanoparticles dispersed in PAO can undergo reversible, melting-freezing phase transition, and exhibit a relatively large hysteresis. The experimental results suggest that the nanoemulsion method is a viable route for mass production of low-melting nanoparticles.

  10. Nickel and platinum group metal nanoparticle production by Desulfovibrio alaskensis G20.

    PubMed

    Capeness, M J; Edmundson, M C; Horsfall, L E

    2015-12-25

    Desulfovibrio alaskensis G20 is an anaerobic sulfate reducing bacteria. While Desulfovibrio species have previously been shown to reduce palladium and platinum to the zero-state, forming nanoparticles in the process; there have been no reports that D. alaskensis is able to form these nanoparticles. Metal nanoparticles have properties that make them ideal for use in many industrial and medical applications, such as their size and shape giving them higher catalytic activity than the bulk form of the same metal. Nanoparticles of the platinum group metals in particular are highly sought after for their catalytic ability and herein we report the formation of both palladium and platinum nanoparticles by D. alaskensis and the biotransformation of solvated nickel ions to nanoparticle form.

  11. Investigation of laser heating effect of metallic nanoparticles on cancer treatment

    NASA Astrophysics Data System (ADS)

    Shan, G. S.; Liu, X. M.; Chen, H. J.; Yu, J. S.; Chen, X. D.; Yao, Y.; Qi, L. M.; Chen, Z. J.

    2016-07-01

    Metallic nanoparticles can be applied for hyperthermia therapy of cancer treatment to enhance the efficacy because of their high absorption rate. The absorption of laser energy by metallic nanoparticles is strongly dependent on the concentration, shape, material of nanoparticles and the wavelength of the laser. However, there is no systematic investigation on the heating effect involving different material, concentration and laser wavelength. In this paper, gold nanoparticles (AuNPs), sliver nanoparticles (AgNPs) and sliver nanowires (AgNWs) with different concentrations are heated by 450nm and 532nm wavelength laser to investigate the heating effect. The result shows that the temperature distribution of heated metallic nanoparticles is non-uniform.

  12. Use of a trabecular metal implant in ankle arthrodesis after failed total ankle replacement

    PubMed Central

    2010-01-01

    Background and purpose Arthrodesis after failed total ankle replacement is complicated and delayed union, nonunion, and shortening of the leg often occur—especially with large bone defects. We investigated the use of a trabecular metal implant and a retrograde intramedullary nail to obtain fusion. Patients and methods 13 patients with a migrated or loose total ankle implant underwent arthrodesis with the use of a retrograde intramedullary nail through a trabecular metal Tibial Cone. The mean follow-up time was 1.4 (0.6–3.4) years. Results At the last examination, 7 patients were pain-free, while 5 had some residual pain but were satisfied with the procedure. 1 patient was dissatisfied and experienced pain and swelling when walking. The implant-bone interfaces showed no radiographic zones or gaps in any patient, indicating union. Interpretation The method is a new way of simplifying and overcoming some of the problems of performing arthrodesis after failed total ankle replacement. PMID:21067435

  13. Metal-Based Nanoparticles and the Immune System: Activation, Inflammation, and Potential Applications

    PubMed Central

    Luo, Yueh-Hsia; Chang, Louis W.; Lin, Pinpin

    2015-01-01

    Nanomaterials, including metal-based nanoparticles, are used for various biological and medical applications. However, metals affect immune functions in many animal species including humans. Different physical and chemical properties induce different cellular responses, such as cellular uptake and intracellular biodistribution, leading to the different immune responses. The goals of this review are to summarize and discuss the innate and adaptive immune responses triggered by metal-based nanoparticles in a variety of immune system models. PMID:26125021

  14. Study and Optimization of Metal Nanoparticles for the Enhanced Efficiency Thin Film Solar Cells

    NASA Astrophysics Data System (ADS)

    Shilpa, G. D.; Subramanyam, T. K.; Sreelakshmi, K.; Uttarakumari

    2016-09-01

    Thin film silicon solar cells have the potential to considerably decrease the cost of photovoltaic. To increase the conversion efficiency of thin film solar cells, nano-sized structures, such as nanoparticle deposition at the front end, were proposed. In the present study, spherical metal nanoparticles such as gold (Au) and silver (Ag) were deployed at the front of the silicon solar cell. The effect of metal nanoparticles on the absorption enhancement factor of the thin film solar cells was investigated using Lumerical Finite Difference Time Domain (FDTD) solutions. Also the influence of geometrical parameters of spherical nanoparticles on absorption enhancement factor was examined. The maximum absorption enhancement factor was achieved by optimizing the geometrical parameters of nanoparticles. The structure with Ag nanoparticles at the front end of the silicon solar cell exhibits higher absorption enhancement factor than the structure with Au nanoparticles.

  15. Role of metal nanoparticles on porosification of silicon by metal induced etching (MIE)

    NASA Astrophysics Data System (ADS)

    Saxena, Shailendra K.; Yogi, Priyanka; Yadav, Pooja; Mishra, Suryakant; Pandey, Haardik; Rai, Hari Mohan; Kumar, Vivek; Sagdeo, Pankaj R.; Kumar, Rajesh

    2016-06-01

    Porosification of silicon (Si) by metal induced etching (MIE) process has been studied here to understand the etching mechanism. The etching mechanism has been discussed on the basis of electron transfer from Si to metal ion (Ag+) and metal to H2O2. Role of silver nanoparticles (AgNPs) in the etching process has been investigated by studying the effect of AgNPs coverage on surface porosity. A quantitative analysis of SEM images, done using Image J, shows a direct correlation between AgNPs coverage and surface porosity after the porosification. Density of Si nanowires (NWs) also varies as a function of AgNPs fractional coverage which reasserts the fact that AgNPs governs the porosification process during MIE. The Raman and PL spectrum show the presence of Si NSs in the samples.

  16. Regulating the spatial distribution of metal nanoparticles within metal-organic frameworks to enhance catalytic efficiency

    PubMed Central

    Yang, Qiu; Liu, Wenxian; Wang, Bingqing; Zhang, Weina; Zeng, Xiaoqiao; Zhang, Cong; Qin, Yongji; Sun, Xiaoming; Wu, Tianpin; Liu, Junfeng; Huo, Fengwei; Lu, Jun

    2017-01-01

    Composites incorporating metal nanoparticles (MNPs) within metal-organic frameworks (MOFs) have broad applications in many fields. However, the controlled spatial distribution of the MNPs within MOFs remains a challenge for addressing key issues in catalysis, for example, the efficiency of catalysts due to the limitation of molecular diffusion within MOF channels. Here we report a facile strategy that enables MNPs to be encapsulated into MOFs with controllable spatial localization by using metal oxide both as support to load MNPs and as a sacrificial template to grow MOFs. This strategy is versatile to a variety of MNPs and MOF crystals. By localizing the encapsulated MNPs closer to the surface of MOFs, the resultant MNPs@MOF composites not only exhibit effective selectivity derived from MOF cavities, but also enhanced catalytic activity due to the spatial regulation of MNPs as close as possible to the MOF surface. PMID:28195131

  17. Regulating the spatial distribution of metal nanoparticles within metal-organic frameworks to enhance catalytic efficiency

    NASA Astrophysics Data System (ADS)

    Yang, Qiu; Liu, Wenxian; Wang, Bingqing; Zhang, Weina; Zeng, Xiaoqiao; Zhang, Cong; Qin, Yongji; Sun, Xiaoming; Wu, Tianpin; Liu, Junfeng; Huo, Fengwei; Lu, Jun

    2017-02-01

    Composites incorporating metal nanoparticles (MNPs) within metal-organic frameworks (MOFs) have broad applications in many fields. However, the controlled spatial distribution of the MNPs within MOFs remains a challenge for addressing key issues in catalysis, for example, the efficiency of catalysts due to the limitation of molecular diffusion within MOF channels. Here we report a facile strategy that enables MNPs to be encapsulated into MOFs with controllable spatial localization by using metal oxide both as support to load MNPs and as a sacrificial template to grow MOFs. This strategy is versatile to a variety of MNPs and MOF crystals. By localizing the encapsulated MNPs closer to the surface of MOFs, the resultant MNPs@MOF composites not only exhibit effective selectivity derived from MOF cavities, but also enhanced catalytic activity due to the spatial regulation of MNPs as close as possible to the MOF surface.

  18. Enhancement of the second-harmonic generation in a quantum dot-metallic nanoparticle hybrid system

    NASA Astrophysics Data System (ADS)

    Singh, Mahi R.

    2013-03-01

    We have investigated the second-harmonic generation (SHG) and dipole-dipole interaction in a quantum dot and metallic nanoparticle hybrid system. A strong probe field is applied to create two-photon absorption in the quantum dot and metallic nanoparticle. SHG photons and SHG surface plasmon polaritons are emitted by the quantum dot and metallic nanoparticle, respectively. Induced dipoles are created in the quantum dot and the metallic nanoparticle due to two-photon absorption and hence both systems interact with each other via the dipole-dipole interaction. It is found that SHG signals produced by the quantum dot and nanoparticle are enhanced by the dipole-dipole interaction and also that the SHG signal can be switched on and off by applying a control field. The theoretical findings of this paper are supported by recent experimental studies. The present hybrid system can be used to fabricate nano-sensors and all-optical nano-switching devices.

  19. Corrosion protection of metal implants by hard biocompatible ceramic coatings deposited by radio-frequency sputtering.

    PubMed

    Sella, C; Martin, J C; Lecoeur, J; Bellier, J P; Harmand, M F; Naji, A; Davidas, J P; Le Chanu, A

    1990-01-01

    Most metals used for orthopaedic and stomatology implants and prostheses belong to the families of titanium or nickel-based and cobalt-based superalloys designed for advanced technology industries (e.g. space, aeronautic and nuclear industries). Ideal materials should be as insoluble and biologically compatible as possible. In the present paper the corrosion behaviour of Ni-Cr and Co-Cr alloys in biological media is evaluated through potentiodynamic polarization tests. It is shown that these metals exhibit some minor release of the component elements and degradation products, which may induce cytotoxic and allergic effects. The corrosion resistance of these alloys can be strongly enhanced by hard ceramic coatings deposited by radio-frequency sputtering. The biocompatibility of coated and uncoated metals is compared from differentiated human cell cultures.

  20. Implantable polymer/metal thin film structures for the localized treatment of cancer by Joule heating

    NASA Astrophysics Data System (ADS)

    Kan-Dapaah, Kwabena; Rahbar, Nima; Theriault, Christian; Soboyejo, Wole

    2015-04-01

    This paper presents an implantable polymer/metal alloy thin film structure for localized post-operative treatment of breast cancer. A combination of experiments and models is used to study the temperature changes due to Joule heating by patterned metallic thin films embedded in poly-dimethylsiloxane. The heat conduction within the device and the surrounding normal/cancerous breast tissue is modeled with three-dimensional finite element method (FEM). The FEM simulations are used to explore the potential effects of device geometry and Joule heating on the temperature distribution and lesion (thermal dose). The FEM model is validated using a gel model that mimics biological media. The predictions are also compared to prior results from in vitro studies and relevant in vivo studies in the literature. The implications of the results are discussed for the potential application of polymer/metal thin film structures in hyperthermic treatment of cancer.

  1. Biofilms Versus Activated Sludge: Considerations in Metal and Metal Oxide Nanoparticle Removal from Wastewater.

    PubMed

    Walden, Connie; Zhang, Wen

    2016-08-16

    The increasing application of metal and metal oxide nanoparticles [Me(O)NPs] in consumer products has led to a growth in concentration of these nanoparticles in wastewater as emerging contaminants. This may pose a threat to ecological communities (e.g., biological nutrient removal units) within treatment plants and those subject to wastewater effluents. Here, the toxicity, fate, and process implications of Me(O)NPs within wastewater treatment, specifically during activated sludge processing and biofilm systems are reviewed and compared. Research showed activated sludge achieves high removal rate of Me(O)NPs by the formation of aggregates through adsorption. However, recent literature reveals evidence that inhibition is likely for nutrient removal capabilities such as nitrification. Biofilm systems were much less studied, but show potential to resist Me(O)NP inhibition and achieve removal through possible retention by sorption. Implicating factors during bacteria-Me(O)NP interactions such as aggregation, surface functionalization, and the presence of organics are summarized. At current modeled levels, neither activated sludge nor biofilm systems can achieve complete removal of Me(O)NPs, thus allowing for long-term environmental exposure of diverse biological communities to Me(O)NPs in streams receiving wastewater effluents. Future research directions are identified throughout in order to minimize the impact of these nanoparticles released.

  2. Colloidal Metal Nanoparticles Prepared by Laser Ablation and their Applications.

    PubMed

    Zhang, Jianming; Claverie, Jerome; Chaker, Mohamed; Ma, Dongling

    2017-02-05

    This review article highlights the recent advances of the synthesis and application of metal nanoparticles (NPs) fabricated via pulsed laser ablation in liquid (PLAL) phase and also introduces relevant NP formation mechanisms. Although wet-chemical approaches have been well established to synthesize colloidal metal NPs with various components and structures, some inherent drawbacks, such as reaction residuals and/or contaminations, largely limit some of their applications. The PLAL method has recently been developed as an alternative approach and received increasing attention for colloidal NP preparation, without involving complicated chemical reactions. In certain cases, by using PLAL, ligand-free and surface-clean NPs can be obtained and well dispersed in liquid, leading to the formation of a "surface-clean" NP dispersion. This unique feature renders PLAL-synthesised metal NPs attractive candidates for many interesting applications in catalysis, biology, sensing, and clean energy generation and storage. We conclude this review by proposing several interesting research directions and future challenges, from PLAL fabrication to applications. We hope this review can serve as a good reference and help with the further development of PLAL-NPs and their diverse applications.

  3. Shape-controlled growth of metal nanoparticles: an atomistic view.

    PubMed

    Konuk, Mine; Durukanoğlu, Sondan

    2016-01-21

    Recent developments in shape-controlled synthesis of metallic nano-particles present a promising path for precisely tuning chemical activity, selectivity, and stability of nano-materials. While previous studies have highlighted the macroscopic description of synthesis processes, there is less understanding as to whether individual atomic-scale processes possess any significant role in controlling the growth of nano-products. The presented molecular static and dynamic simulations are the first simulations to understand the underlying atomistic mechanisms of the experimentally determined growth modes of metal nano-clusters. Our simulations on Ag nano-cubes confirm that metal nano-seeds enclosed by {100} facets can be directed to grow into octopods, concave, truncated cubes, and cuboctahedra when the relative surface diffusion and deposition rates are finely tuned. Here we further showed that atomic level processes play a significant role in controllably fine tuning the two competing rates: surface diffusion and deposition. We also found that regardless of temperature and the initial shape of the nano-seeds, the exchange of the deposited atom with an edge atom of the seed is by far the governing diffusion mechanism between the neighboring facets, and thus is the leading atomistic process determining the conditions for fine tuning of macroscopic processes.

  4. Toxicology of wear particles of cobalt-chromium alloy metal-on-metal hip implants Part II: Importance of physicochemical properties and dose in animal and in vitro studies as a basis for risk assessment.

    PubMed

    Madl, Amy K; Kovochich, Michael; Liong, Monty; Finley, Brent L; Paustenbach, Dennis J; Oberdörster, Günter

    2015-07-01

    The objective of the Part II analysis was to evaluate animal and in vitro toxicology studies of CoCr particles with respect to their physicochemistry and dose relevance to metal-on-metal (MoM) implant patients as derived from Part I. In the various toxicology studies, physicochemical characteristics were infrequently considered and administered doses were orders of magnitude higher than what occurs in patients. Co was consistently shown to rapidly release from CoCr particles for distribution and elimination from the body. CoCr micron sized particles appear more biopersistent in vivo resulting in inflammatory responses that are not seen with similar mass concentrations of nanoparticles. We conclude, that in an attempt to obtain data for a complete risk assessment, future studies need to focus on physicochemical characteristics of nano and micron sized particles and on doses and dose metrics relevant to those generated in patients or in properly conducted hip simulator studies.

  5. Engineered metal nanoparticles in the sub-nanomolar levels kill cancer cells

    PubMed Central

    Vodyanoy, Vitaly; Daniels, Yasmine; Pustovyy, Oleg; MacCrehan, William A; Muramoto, Shin; Stan, Gheorghe

    2016-01-01

    Background Small metal nanoparticles obtained from animal blood were observed to be toxic to cultured cancer cells, whereas noncancerous cells were much less affected. In this work, engineered zinc and copper metal nanoparticles were produced from bulk metal rods by an underwater high-voltage discharge method. The metal nanoparticles were characterized by atomic force microscopy and X-ray photoelectron spectroscopy. The metal nanoparticles, with estimated diameters of 1 nm–2 nm, were determined to be more than 85% nonoxidized. A cell viability assay and high-resolution light microscopy showed that exposure of RG2, cultured rat brain glioma cancer cells, to the zinc and copper nanoparticles resulted in cell morphological changes, including decreased cell adherence, shrinking/rounding, nuclear condensation, and budding from cell bodies. The metal-induced cell injuries were similar to the effects of staurosporine, an active apoptotic reagent. The viability experiments conducted for zinc and copper yielded values of dissociation constants of 0.22±0.08 nmol/L (standard error [SE]) and 0.12±0.02 nmol/L (SE), respectively. The noncancerous astrocytes were not affected at the same conditions. Because metal nanoparticles were lethal to the cancer cells at sub-nanomolar concentrations, they are potentially important as nanomedicine. Purpose Lethal concentrations of synthetic metal nanoparticles reported in the literature are a few orders of magnitude higher than the natural, blood-isolated metal nanoparticles; therefore, in this work, engineered metal nanoparticles were examined to mimic the properties of endogenous metal nanoparticles. Materials and methods RG2, rat brain glioma cells CTX TNA2 brain rat astrocytes, obtained from the American Type Culture Collection, high-voltage discharge, atomic force microscope, X-ray photoelectron spectroscopy, high-resolution light microscopy, zeta potential measurements, and 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium

  6. Ultrahigh-current-density metal-ion implantation and diamondlike-hydrocarbon films for tribological applications; Final report

    SciTech Connect

    Wilbur, P.J.

    1993-09-01

    The metal-ion-implantation system used to implant metals into substrates are described. The metal vapor required for operation is supplied by drawing sufficient electron current from the plasma discharge to an anode-potential crucible so a solid, pure metal placed in the crucible will be heated to the point of vaporization. The ion-producing, plasma discharge is initiated within a graphite-ion-source body, which operates at high temperature, by using an argon flow that is turned off once the metal vapor is present. Extraction of ion beams several cm in diameter at current densities ranging to several hundred {mu}A/cm{sup 2} on a target 50 cm downstream of the ion source have been demonstrated using Mg, Ag, Cr, Cu, Si, Ti, V, B and Zr. These metals were implanted into over 100 substrates (discs, pins, flats, wires). A model describing thermal stresses induced in materials (e.g. ceramic plates) during high-current-density implantation is presented. Tribological and microstructural characteristics of iron and 304-stainless-steel samples implanted with Ti or B are examined. Diamondlike-hydrocarbon coatings were applied to steel surfaces and found to exhibit good tribological performance.

  7. Surface engineering of a Zr-based bulk metallic glass with low energy Ar- or Ca-ion implantation.

    PubMed

    Huang, Lu; Zhu, Chao; Muntele, Claudiu I; Zhang, Tao; Liaw, Peter K; He, Wei

    2015-02-01

    In the present study, low energy ion implantation was employed to engineer the surface of a Zr-based bulk metallic glass (BMG), aiming at improving the biocompatibility and imparting bioactivity to the surface. Ca- or Ar-ions were implanted at 10 or 50 keV at a fluence of 8 × 10(15)ions/cm(2) to (Zr0.55Al0.10Ni0.05Cu0.30)99Y1 (at.%) BMG. The effects of ion implantation on material properties and subsequent cellular responses were investigated. Both Ar- and Ca-ion implantations were suggested to induce atom displacements on the surfaces according to the Monte-Carlo simulation. The change of atomic environment of Zr in the surface regions as implied by the alteration in X-ray absorption measurements at Zr K-edge. X-ray photoelectron spectroscopy revealed that the ion implantation process has modified the surface chemical compositions and indicated the presence of Ca after Ca-ion implantation. The surface nanohardness has been enhanced by implantation of either ion species, with Ca-ion implantation showing more prominent effect. The BMG surfaces were altered to be more hydrophobic after ion implantation, which can be attributed to the reduced amount of hydroxyl groups on the implanted surfaces. Higher numbers of adherent cells were found on Ar- and Ca-ion implanted samples, while more pronounced cell adhesion was observed on Ca-ion implanted substrates. The low energy ion implantation resulted in concurrent modifications in atomic structure, nanohardness, surface chemistry, hydrophobicity, and cell behavior on the surface of the Zr-based BMG, which were proposed to be mutually correlated with each other.

  8. Synthesis of Metal Nanoparticles and Metal Fluoride Nanoparticles from Metal Amidinate Precursors in 1‐Butyl‐3‐Methylimidazolium Ionic Liquids and Propylene Carbonate

    PubMed Central

    Schütte, Kai; Barthel, Juri; Endres, Manuel; Siebels, Marvin; Smarsly, Bernd M.; Yue, Junpei

    2016-01-01

    Abstract Decomposition of transition‐metal amidinates [M{MeC(NiPr)2}n] [M(AMD)n; M=MnII, FeII, CoII, NiII, n=2; CuI, n=1) induced by microwave heating in the ionic liquids (ILs) 1‐butyl‐3‐methylimidazolium tetrafluoroborate ([BMIm][BF4]), 1‐butyl‐3‐methylimidazolium hexafluorophosphate ([BMIm][PF6]), 1‐butyl‐3‐methylimidazolium trifluoromethanesulfonate (triflate) ([BMIm][TfO]), and 1‐butyl‐3‐methylimidazolium tosylate ([BMIm][Tos]) or in propylene carbonate (PC) gives transition‐metal nanoparticles (M‐NPs) in non‐fluorous media (e.g. [BMIm][Tos] and PC) or metal fluoride nanoparticles (MF2‐NPs) for M=Mn, Fe, and Co in [BMIm][BF4]. FeF2‐NPs can be prepared upon Fe(AMD)2 decomposition in [BMIm][BF4], [BMIm][PF6], and [BMIm][TfO]. The nanoparticles are stable in the absence of capping ligands (surfactants) for more than 6 weeks. The crystalline phases of the metal or metal fluoride synthesized in [BMIm][BF4] were identified by powder X‐ray diffraction (PXRD) to exclusively Ni‐ and Cu‐NPs or to solely MF2‐NPs for M=Mn, Fe, and Co. The size and size dispersion of the nanoparticles were determined by transmission electron microscopy (TEM) to an average diameter of 2(±2) to 14(±4) nm for the M‐NPs, except for the Cu‐NPs in PC, which were 51(±8) nm. The MF2‐NPs from [BMIm][BF4] were 15(±4) to 65(±18) nm. The average diameter from TEM is in fair agreement with the size evaluated from PXRD with the Scherrer equation. The characterization was complemented by energy‐dispersive X‐ray spectroscopy (EDX). Electrochemical investigations of the CoF2‐NPs as cathode materials for lithium‐ion batteries were simply evaluated by galvanostatic charge/discharge profiles, and the results indicated that the reversible capacity of the CoF2‐NPs was much lower than the theoretical value, which may have originated from the complex conversion reaction mechanism and residue on the surface of the nanoparticles. PMID:28168159

  9. Directed liquid phase assembly of highly ordered metallic nanoparticle arrays

    DOE PAGES

    Wu, Yueying; Dong, Nanyi; Fu, Shaofang; ...

    2014-04-01

    Directed assembly of nanomaterials is a promising route for the synthesis of advanced materials and devices. We demonstrate the directed-assembly of highly ordered two-dimensional arrays of hierarchical nanostructures with tunable size, spacing and composition. The directed assembly is achieved on lithographically patterned metal films that are subsequently pulse-laser melted; during the brief liquid lifetime, the pattened nanostructures assemble into highly ordered primary and secondary nanoparticles, with sizes below that which was originally patterned. Complementary fluid-dynamics simulations emulate the resultant patterns and show how the competition of capillary forces and liquid metal–solid substrate interaction potential drives the directed assembly. Lastly, asmore » an example of the enhanced functionality, a full-wave electromagnetic analysis has been performed to identify the nature of the supported plasmonic resonances.« less

  10. Directed liquid phase assembly of highly ordered metallic nanoparticle arrays

    SciTech Connect

    Wu, Yueying; Dong, Nanyi; Fu, Shaofang; Fowlkes, Jason D.; Kondic, Lou; Vincenti, Maria A.; de Ceglia, Domenico; Rack, Philip D.

    2014-04-01

    Directed assembly of nanomaterials is a promising route for the synthesis of advanced materials and devices. We demonstrate the directed-assembly of highly ordered two-dimensional arrays of hierarchical nanostructures with tunable size, spacing and composition. The directed assembly is achieved on lithographically patterned metal films that are subsequently pulse-laser melted; during the brief liquid lifetime, the pattened nanostructures assemble into highly ordered primary and secondary nanoparticles, with sizes below that which was originally patterned. Complementary fluid-dynamics simulations emulate the resultant patterns and show how the competition of capillary forces and liquid metal–solid substrate interaction potential drives the directed assembly. Lastly, as an example of the enhanced functionality, a full-wave electromagnetic analysis has been performed to identify the nature of the supported plasmonic resonances.

  11. Engineering Metallic Nanoparticles for Enhancing and Probing Catalytic Reactions.

    PubMed

    Collins, Gillian; Holmes, Justin D

    2016-07-01

    Recent developments in tailoring the structural and chemical properties of colloidal metal nanoparticles (NPs) have led to significant enhancements in catalyst performance. Controllable colloidal synthesis has also allowed tailor-made NPs to serve as mechanistic probes for catalytic processes. The innovative use of colloidal NPs to gain fundamental insights into catalytic function will be highlighted across a variety of catalytic and electrocatalytic applications. The engineering of future heterogenous catalysts is also moving beyond size, shape and composition considerations. Advancements in understanding structure-property relationships have enabled incorporation of complex features such as tuning surface strain to influence the behavior of catalytic NPs. Exploiting plasmonic properties and altering colloidal surface chemistry through functionalization are also emerging as important areas for rational design of catalytic NPs. This news article will highlight the key developments and challenges to the future design of catalytic NPs.

  12. Dirac plasmons in bipartite lattices of metallic nanoparticles

    NASA Astrophysics Data System (ADS)

    Jebb Sturges, Thomas; Woollacott, Claire; Weick, Guillaume; Mariani, Eros

    2015-03-01

    We study theoretically ‘graphene-like’ plasmonic metamaterials constituted by two-dimensional arrays of metallic nanoparticles, including perfect honeycomb structures with and without inversion symmetry, as well as generic bipartite lattices. The dipolar interactions between localized surface plasmons (LSPs) in different nanoparticles gives rise to collective plasmons (CPs) that extend over the whole lattice. We study the band structure of CPs and unveil its tunability with the orientation of the dipole moments associated with the LSPs. Depending on the dipole orientation, we identify a phase diagram of gapless or gapped phases in the CP dispersion. We show that the gapless phases in the phase diagram are characterized by CPs behaving as massless chiral Dirac particles, in analogy with electrons in graphene. When the inversion symmetry of the honeycomb structure is broken, CPs are described as gapped chiral Dirac modes with an energy-dependent Berry phase. We further relax the geometric symmetry of the honeycomb structure by analysing generic bipartite hexagonal lattices. In this case we study the evolution of the phase diagram and unveil the emergence of a sequence of topological phase transitions when one hexagonal sublattice is progressively shifted with respect to the other.

  13. Inhomogeneous depletion of oxygen ions in metal oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Vykhodets, Vladimir B.; Jarvis, Emily A. A.; Kurennykh, Tatiana E.; Beketov, Igor V.; Obukhov, Sviatoslav I.; Samatov, Oleg M.; Medvedev, Anatoly I.; Davletshin, Andrey E.; Whyte, Travis H.

    2016-02-01

    Zirconia and yttria stabilized zirconia (YSZ) have multiple uses, including catalysis, fuel cells, dental applications, and thermal coatings. We employ nuclear reaction analysis to determine elemental composition of YSZ nanoparticles synthesized by laser evaporation including 18O studies to distinguish between oxide and adsorbed oxygen content as a function of surface area. We see dramatic deviation from stoichiometry that can be traced to loss of oxygen from the oxide near the surface of these nanopowders. Density functional calculations are coupled with these experimental studies to explore the electronic structure of nonstoichiometric surfaces achieved through depletion of oxygen. Our results show oxygen-depleted surfaces present under oxygen potentials where stoichiometric, oxygen-terminated surfaces would be favored thermodynamically for crystalline systems. Oxygen depletion at nanopowder surfaces can create effective two-dimensional surface metallic states while maintaining stoichiometry in the underlying nanoparticle core. This insight into nanopowder surfaces applies to dissimilar oxides of aluminum and zirconium indicating synthesis conditions may be more influential than the inherent oxide properties and displaying need for distinct models for nanopowders of these important engineering materials where surface chemistry dominates performance.

  14. Dirac-like plasmons in honeycomb lattices of metallic nanoparticles.

    PubMed

    Weick, Guillaume; Woollacott, Claire; Barnes, William L; Hess, Ortwin; Mariani, Eros

    2013-03-08

    We consider a two-dimensional honeycomb lattice of metallic nanoparticles, each supporting a localized surface plasmon, and study the quantum properties of the collective plasmons resulting from the near-field dipolar interaction between the nanoparticles. We analytically investigate the dispersion, the effective Hamiltonian, and the eigenstates of the collective plasmons for an arbitrary orientation of the individual dipole moments. When the polarization points close to the normal to the plane, the spectrum presents Dirac cones, similar to those present in the electronic band structure of graphene. We derive the effective Dirac Hamiltonian for the collective plasmons and show that the corresponding spinor eigenstates represent Dirac-like massless bosonic excitations that present similar effects to electrons in graphene, such as a nontrivial Berry phase and the absence of backscattering off smooth inhomogeneities. We further discuss how one can manipulate the Dirac points in the Brillouin zone and open a gap in the collective plasmon dispersion by modifying the polarization of the localized surface plasmons, paving the way for a fully tunable plasmonic analogue of graphene.

  15. Synthesis and optical properties of anisotropic metal nanoparticles.

    PubMed

    Hao, Encai; Schatz, George C; Hupp, Joseph T

    2004-07-01

    In this paper we overview our recent studies of anisotropic noble metal (e.g. gold and silver) nanoparticles, in which a combination of theory and experiment has been used to elucidate the extinction spectra of the particles, as well as information related to their surface enhanced Raman spectroscopy. We used wet-chemical methods to generate several structurally well-defined nanostructures other than solid spheres, including silver nanodisks and triangular nanoprisms, and gold nanoshells and multipods. When solid spheres are transformed into one of these shapes, the surface plasmon resonances in these particles are strongly affected, typically red-shifting and even splitting into distinctive dipole and quadrupole plasmon modes. In parallel, we have developed computational electrodynamics methods based on the discrete dipole approximation (DDA) method to determine the origins of these intriguing optical features. This has resulted in considerable insight concerning the variation of plasmon wavelength with nanoparticle size, shape and dielectric environment, as well as the use of these particles for optical sensing applications.

  16. Magnetic metal nanoparticles coated polyacrylonitrile textiles as microwave absorber

    NASA Astrophysics Data System (ADS)

    Akman, O.; Kavas, H.; Baykal, A.; Toprak, M. S.; Çoruh, Ali; Aktaş, B.

    2013-02-01

    Polyacrylonitrile (PAN) textiles with 2 mm thickness are coated with magnetic nanoparticles in coating baths with Ni, Co and their alloys via an electroless metal deposition method. The crystal structure, morphology and magnetic nature of composites are investigated by X-ray Powder diffraction, Scanning Electron Microscopy, and dc magnetization measurement techniques. The frequency dependent microwave absorption measurements have been carried out in the frequency range of 12.4-18 GHz (X and P bands). Diamagnetic and ferromagnetic properties are also investigated. Finally, the microwave absorption of composites is found strongly dependent on the coating time. One absorption peak is observed between 14.3 and 15.8 GHz with an efficient absorption bandwidth of 3.3-4.1 GHz (under -20 dB reflection loss limit). The Reflection loss (RL) can be achieved between -30 and -50 dB. It was found that the RL is decreasing and absorption bandwidth is decreasing with increasing coating time. While absorption peak moves to lower frequencies in Ni coated PAN textile, it goes higher frequencies in Co coated ones. The Ni-Co alloy coated composites have fluctuating curve of absorption frequency with respect to coating time. These results encourage further development of magnetic nanoparticle coated textile absorbers for broadband applications.

  17. Magnetic moment of a single metal nanoparticle determined from the Faraday effect

    NASA Astrophysics Data System (ADS)

    Szczytko, Jacek; Vaupotič, Nataša; Madrak, Karolina; Sznajder, Paweł; Górecka, Ewa

    2013-03-01

    Optical properties of a composite material made of ferromagnetic metal nanoparticles embedded in a dielectric host are studied. We constructed an effective dielectric tensor of the composite material taking into account the orientational distribution of nanoparticle magnetic moments in external magnetic field. A nonlinear dependence of the optical rotation on magnetic field resulting from the reorientation of nanoparticles is demonstrated. The theoretical findings were applied to the magneto-optical experimental data of cobalt ferromagnetic nanoparticles embedded in a dielectric liquid host. The dependence of the Faraday rotation on Co-based ferromagnetic nanoparticles was measured as a function of the external magnetic field, varying the size of nanoparticles and the wavelength of light. The proposed approach enables quantitative determination of the magnetic moment and the plasma frequency of a single nanoparticle, and from this the size of the nonmagnetic shell of magnetic nanoparticles.

  18. Nonspherical noble metal nanoparticles: colloid-chemical synthesis and morphology control.

    PubMed

    Sau, Tapan K; Rogach, Andrey L

    2010-04-22

    Metal nanoparticles have been the subject of widespread research over the past two decades. In recent years, noble metals have been the focus of numerous studies involving synthesis, characterization, and applications. Synthesis of an impressive range of noble metal nanoparticles with varied morphologies has been reported. Researchers have made a great progress in learning how to engineer materials on a nanometer length scale that has led to the understanding of the fundamental size- and shape-dependent properties of matter and to devising of new applications. In this article, we review the recent progress in the colloid-chemical synthesis of nonspherical nanoparticles of a few important noble metals (mainly Ag, Au, Pd, and Pt), highlighting the factors that influence the particle morphology and discussing the mechanisms behind the nonspherical shape evolution. The article attempts to present a thorough discussion of the basic principles as well as state-of-the-art morphology control in noble metal nanoparticles.

  19. Synthesis of Metal Nanoparticle-decorated Carbon Nanotubes under Ambient Conditions

    NASA Technical Reports Server (NTRS)

    Lin, Yi; Watson, Kent A.; Ghose, Sayata; Smith, Joseph G.; Connell, John W.

    2008-01-01

    This viewgraph presentation reviews the production of Metal Nanoparticle-decorated carbon Nanotubes. Multi-walled carbon nanotubes (MWCNTs) were efficiently decorated with metal nanoparticles (e.g. Ag, Pt, etc.) using the corresponding metal acetate in a simple mixing process without the need of chemical reagents or further processing. The conversion of acetate compounds to the corresponding metal reached over 90%, forming nanoparticles with average diameters less than 10 nm under certain conditions. The process was readily scalable allowing for the convenient preparation of multi-gram quantities of metal nanoparticle-decorated MWCNTs in a matter of a few minutes. These materials are under evaluation for a variety of electrical and catalytic applications. The preparation and characterization of these materials will be presented. The microscopic views of the processed MWCNTs are shown

  20. Solution synthesis of mixed-metal chalcogenide nanoparticles and spray deposition of precursor films

    DOEpatents

    Schulz, Douglas L.; Curtis, Calvin J.; Ginley, David S.

    2000-01-01

    A colloidal suspension comprising metal chalcogenide nanoparticles and a volatile capping agent. The colloidal suspension is made by reacting a metal salt with a chalcogenide salt in an organic solvent to precipitate a metal chalcogenide, recovering the metal chalcogenide, and admixing the metal chalcogenide with a volatile capping agent. The colloidal suspension is spray deposited onto a substrate to produce a semiconductor precursor film which is substantially free of impurities.

  1. Are all metal-on-metal hip revision operations contributing to the National Joint Registry implant survival curves?

    PubMed Central

    Sabah, S. A.; Henckel, J.; Koutsouris, S.; Rajani, R.; Hothi, H.; Skinner, J. A.; Hart, A. J.

    2016-01-01

    Aims The National Joint Registry for England, Wales and Northern Ireland (NJR) has extended its scope to report on hospital, surgeon and implant performance. Data linkage of the NJR to the London Implant Retrieval Centre (LIRC) has previously evaluated data quality for hip primary procedures, but did not assess revision records. Methods We analysed metal-on-metal hip revision procedures performed between 2003 and 2013. A total of 69 929 revision procedures from the NJR and 929 revised pairs of components from the LIRC were included. Results We were able to link 716 (77.1%) revision procedures on the NJR to the LIRC. This meant that 213 (22.9%) revision procedures at the LIRC could not be identified on the NJR. We found that 349 (37.6%) explants at the LIRC completed the full linkage process to both NJR primary and revision databases. Data completion was excellent (> 99.9%) for revision procedures reported to the NJR. Discussion This study has shown that only approximately one third of retrieved components at the LIRC, contributed to survival curves on the NJR. We recommend prospective registry-retrieval linkage as a tool to feedback missing and erroneous data to the NJR and improve data quality. Take home message: Prospective Registry – retrieval linkage is a simple tool to evaluate and improve data quality on the NJR. Cite this article: Bone Joint J 2016;98-B:33–9. PMID:26733513

  2. [Influence of implants on human body during MRI examinations: fundamental experiment using metal balls].

    PubMed

    Muranaka, Hiroyuki; Nakamura, Osamu; Usui, Shuji; Ueda, Yoshitake; Morikawa, Kaoru

    2005-07-20

    It is increasingly the case that patients who have implants feel pain during high-field MRI examinations. A probable reason for the pain is the generation by irradiation of RF pulses and changing of the magnetic field gradient. As a fundamental study on the effect of implants on the human body under MRI procedures, temperature measurements were obtained from metal balls incorporated into gel-filled phantoms by using two kinds of measuring instruments, a copper-constantan thermocouple and a fluorescence fiber thermometer. At first we pursued a correlation between a copper-constantan thermocouple (absolute measurement) and fluoroptic thermometer and confirmed the precision and stability of the fluoroptic thermometer under MRI procedures. When a stainless steel ball with or without a loop antenna was used, only in the former case did the temperature rise during RF pulse irradiation. There was no significant difference between the magnetic field gradient ON and OFF. Furthermore, differences in metal (steel, aluminum, brass, stainless steel, copper) and size (5, 10, 20 mmPhi) were affected according to the increase of temperature. In conclusion, both RF pulse irradiation and a loop antenna are necessary for heat generation on the surface of metals.

  3. Mechanisms of formation of nonlinear optical light guide structures in metal cluster composites produced by ion beam implantation

    SciTech Connect

    Sarkisov, S.S.; Williams, E.K.; Curley, M.; Smith, C.C.; Ila, D.; Venkateswarlu, P.; Poker, D.B.; Hensley, D.K.

    1997-11-01

    Ion implantation has been shown to produce a high density of metal colloids in glasses and crystalline materials. The high-precipitate volume fraction and small size of metal nanoclusters formed leads to values for the third-order susceptibility much greater than those for metal doped solids. This has stimulated interest in use of ion implantation to make nonlinear optical materials. On the other side, LiNbO{sub 3} has proved to be a good material for optical waveguides produced by MeV ion implantation. Light confinement in these waveguides is produced by refractive index step difference between the implanted region and the bulk material. Implantation of LiNbO{sub 3} with MeV metal ions can therefore result into nonlinear optical waveguide structures with great potential in a variety of device applications. The authors describe linear and nonlinear optical properties of a waveguide structure in LiNbO{sub 3}-based composite material produced by silver ion implantation in connection with mechanisms of its formation.

  4. In vivo imaging of melanoma-implanted magnetic nanoparticles using contrast-enhanced magneto-motive optical Doppler tomography

    NASA Astrophysics Data System (ADS)

    Wijesinghe, Ruchire Eranga; Park, Kibeom; Kim, Dong-Hyeon; Jeon, Mansik; Kim, Jeehyun

    2016-06-01

    We conducted an initial feasibility study using real-time magneto-motive optical Doppler tomography (MM-ODT) with enhanced contrast to investigate the detection of superparamagnetic iron oxide (SPIO) magnetic nanoparticles implanted into in vivo melanoma tissue. The MM-ODT signals were detected owing to the phase shift of the implanted magnetic nanoparticles, which occurred due to the action of an applied magnetic field. An amplifier circuit-based solenoid was utilized for generating high-intensity oscillating magnetic fields. The MM-ODT system was confirmed as an effective in vivo imaging method for detecting melanoma tissue, with the performance comparable to those of conventional optical coherence tomography and optical Doppler tomography methods. Moreover, the optimal values of the SPIO nanoparticles concentration and solenoid voltage for obtaining the uppermost Doppler velocity were derived as well. To improve the signal processing speed for real-time imaging, we adopted multithread programming techniques and optimized the signal path. The results suggest that this imaging modality can be used as a powerful tool to identify the intracellular and extracellular SPIO nanoparticles in melanoma tissues in vivo.

  5. Photoresponse from noble metal nanoparticles-multi walled carbon nanotube composites

    SciTech Connect

    Scarselli, M.; Camilli, L.; Castrucci, P.; De Crescenzi, M.; Matthes, L.; Pulci, O.; Gatto, E.; Venanzi, M.

    2012-12-10

    In this Letter, we investigated the photo-response of multi wall carbon nanotube-based composites obtained from in situ thermal evaporation of noble metals (Au, Ag, and Cu) on the nanotube films. The metal deposition process produced discrete nanoparticles on the nanotube outer walls. The nanoparticle-carbon nanotube films were characterized by photo-electrochemical measurements in a standard three electrode cell. The photocurrent from the decorated carbon nanotubes remarkably increased with respect to that of bare multiwall tubes. With the aid of first-principle calculations, these results are discussed in terms of metal nanoparticle-nanotube interactions and electronic charge transfer at the interface.

  6. Metal nanoparticles in liquid phase catalysis; from recent advances to future goals.

    PubMed

    Zahmakıran, Mehmet; Ozkar, Saim

    2011-09-01

    Metal nanoparticles have attracted much attention over the last decade owing to their unique properties, different to their bulk counterparts, which pave the way for their application in different fields from materials science and engineering to biomedical applications. Of particular interest, the use of metal nanoparticles in catalysis has brought superior efficiency in terms of activity, selectivity and lifetime to heterogeneous catalysis. This article reviews the recent developments in the synthesis routes and the catalytic performance of metal nanoparticles depending on the solvent used for various organic and inorganic transformations. Additionally, we also discuss the prevalent complications and their possible solutions plus future prospects in the field of nanocatalysis.

  7. Tissue Reaction and Biocompatibility of Implanted Mineral Trioxide Aggregate with Silver Nanoparticles in a Rat Model

    PubMed Central

    Zand, Vahid; Lotfi, Mehrdad; Aghbali, Amirala; Mesgariabbasi, Mehran; Janani, Maryam; Mokhtari, Hadi; Tehranchi, Pardis; Pakdel, Seyyed Mahdi Vahid

    2016-01-01

    Introduction: Biocompatibility and antimicrobial activity of endodontic materials are of utmost importance. Considering the extensive applications of mineral trioxide aggregate (MTA) in dentistry and antimicrobial properties of silver nanoparticles, this study aimed to evaluate the subcutaneous inflammatory reaction of rat connective tissues to white MTA with and without nanosilver (NS) particles. Methods and Materials: Polyethylene tubes (1.1×8 mm) containing experimental materials (MTA and MTA+NS and empty control tubes) were implanted in subcutaneous tissues of seventy-five male rats. Animals were divided into five groups (n=15) according to the time of evaluation: group 1; after 7 days, group 2; after 15 days, group 3; after 30 days, group 4; after 60 days and group 5; after 90 days. The inflammatory reaction was graded and data was analyzed using the Kruskal-Wallis and Mann-Whitney U tests. Statistical significance was defined at 0.05. Results: Comparison of cumulative inflammatory reaction at all intervals revealed that the mean grade of inflammatory reaction to MTA, MTA+NS and control samples were 3, 2 and 2, respectively. According to the Mann-Whitney analysis there were no significant differences between MTA+NS and MTA (P=0.42). Conclusion: Incorporation of 1% nanosilver to MTA does not affect the inflammatory reaction of subcutaneous tissue in rat models. PMID:26843871

  8. Corrosion resistance of Ti modified by chitosan-gold nanoparticles for orthopedic implantation.

    PubMed

    Farghali, R A; Fekry, A M; Ahmed, Rasha A; Elhakim, H K A

    2015-08-01

    Highly uniform bionanocomposite film composed of chitosan (CS) and gold nanoparticles (AuNPs) was synthesized successfully by electrodeposition method. The influence of AuNPs/CS bionanocomposite film on corrosion resistance of Ti was investigated. Surface morphology and compositional properties of the bionanocomposite were analyzed by scanning electron microscope (SEM), energy dispersive X-ray analysis (EDX), and X-ray photoelectron spectroscopy (XPS). Moreover, cyclic voltammetry (CV), open-circuit potential measurements (OCP), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (Rp) were used to examine the corrosion behavior in Hanks' solution. In comparison with Ti, Nyquist and Bode plots displayed higher impedance values and phase angles for AuNPs/CS biocomposite denoting a more protective passive film on Ti with inhibition efficiency (IE%) of 98%. An electric equivalent circuit with three time constants was modeled for the bionanocomposite. In addition, the antibacterial effect revealed the high efficiencies of the bionanocomposite film for inhibiting bacterial growth. The combination of the high biocompatibility of chitosan and strong adsorption ability of AuNPs make AuNPs/CS bionanocomposite promising candidate for modifying biomaterial surfaces for medical implantation applications.

  9. Bare metal or drug-eluting stent implantation in last remaining vessel PCI? A serious dilemma.

    PubMed

    Zhang, Lei; Zhu, Jianhua; Kiemeneij, Ferdinand

    2009-04-01

    This case report describes the treatment of an old male diabetic patient with last remaining vessel coronary artery disease and poor left ventricular function. In presence of an old occlusion of the left main coronary artery, a subtotal stenosis of a dominant right coronary artery required angioplasty. After ample consideration it was decided to implant a bare metal stent (BMS) instead of a drug-eluting stent (DES). The major reason was the fear for early discontinuation of clopidogrel in case a drug-eluting stent was placed. The procedure and follow-up are described followed by an overview of current literature concerning similar pathology.

  10. Surface modification of traditional and bioresorbable metallic implant materials for improved biocompatibility

    NASA Astrophysics Data System (ADS)

    Walker, Emily K.

    Due to their strength, elasticity, and durability, a variety of metal alloys are commonly used in medical implants. Traditionally, corrosion-resistant metals have been preferred. These permanent materials can cause negative systemic and local tissue effects in the long-term. Permanent stenting can lead to late-stent thrombosis and in-stent restenosis. Metallic pins and screws for fracture fixation can corrode and fail, cause loss of bone mass, and contribute to inflammation and pain at the implant site, requiring reintervention. Corrodible metallic implants have the potential to prevent many of these complications by providing transient support to the affected tissue, dissolving at a rate congruent with the healing of the tissue. Alloys of iron and manganese (FeMn) exhibit similar fatigue strength, toughness, and elasticity compared with 316L stainless steel, making them very attractive candidates for bioresorbable stents and temporary fracture fixation devices. Much attention in recent years has been given to creating alloys with ideal mechanical properties for various applications. Little work has been done on determining the blood compatibility of these materials or on examining how their surfaces can be improved to improve cell adhesion, however. We examined thethrombogenic response of blood exposed to various resorbable ferrous stent materials through contact with porcine blood. The resorbable materials induced comparable or lower levels of several coagulation factors compared with 316L stainless steel. Little platelet adhesion was observed on any of the tested materials. Endothelialization is an important process after the implantation of a vascular stent, as it prevents damage to the vessel wall that can accelerate neointimal hyperplasia. Micromotion can lead to the formation of fibrous tissue surrounding an orthopedic implant, loosening, and ultimately failure of the implant. Nanoscale features were created on the surfaces of noble metal coatings, silicon

  11. Effects of helium implantation on the tensile properties and microstructure of Ni₇₃P₂₇ metallic glass nanostructures

    SciTech Connect

    Liontas, Rachel; Gu, X. Wendy; Fu, Engang; Wang, Yongqiang; Li, Nan; Mara, Nathan; Greer, Julia R.

    2014-09-10

    We report fabrication and nanomechanical tension experiments on as-fabricated and helium-implanted ~130 nm diameter Ni₇₃P₂₇ metallic glass nano-cylinders. The nano-cylinders were fabricated by a templated electroplating process and implanted with He⁺ at energies of 50, 100, 150, and 200 keV to create a uniform helium concentration of ~3 at. % throughout the nano-cylinders. Transmission electron microscopy (TEM) imaging and through-focus analysis reveal that the specimens contained ~2 nm helium bubbles distributed uniformly throughout the nano-cylinder volume. In-situ tensile experiments indicate that helium-implanted specimens exhibit enhanced ductility as evidenced by a 2-fold increase in plastic strain over as-fabricated specimens, with no sacrifice in yield and ultimate tensile strengths. This improvement in mechanical properties suggests that metallic glasses may actually exhibit a favorable response to high levels of helium implantation.

  12. Effects of helium implantation on the tensile properties and microstructure of Ni₇₃P₂₇ metallic glass nanostructures

    DOE PAGES

    Liontas, Rachel; Gu, X. Wendy; Fu, Engang; ...

    2014-09-10

    We report fabrication and nanomechanical tension experiments on as-fabricated and helium-implanted ~130 nm diameter Ni₇₃P₂₇ metallic glass nano-cylinders. The nano-cylinders were fabricated by a templated electroplating process and implanted with He⁺ at energies of 50, 100, 150, and 200 keV to create a uniform helium concentration of ~3 at. % throughout the nano-cylinders. Transmission electron microscopy (TEM) imaging and through-focus analysis reveal that the specimens contained ~2 nm helium bubbles distributed uniformly throughout the nano-cylinder volume. In-situ tensile experiments indicate that helium-implanted specimens exhibit enhanced ductility as evidenced by a 2-fold increase in plastic strain over as-fabricated specimens, with nomore » sacrifice in yield and ultimate tensile strengths. This improvement in mechanical properties suggests that metallic glasses may actually exhibit a favorable response to high levels of helium implantation.« less

  13. High-performance heterogeneous catalysis with surface-exposed stable metal nanoparticles.

    PubMed

    Huang, Ning; Xu, Yanhong; Jiang, Donglin

    2014-11-27

    Protection of metal nanoparticles from agglomeration is critical for their functions and applications. The conventional method for enhancing their stability is to cover them with passivation layers to prevent direct contact. However, the presence of a protective shell blocks exposure of the metal species to reactants, thereby significantly impeding the nanoparticles' utility as catalysts. Here, we report that metal nanoparticles can be prepared and used in a surface-exposed state that renders them inherently catalytically active. This strategy is realised by spatial confinement and electronic stabilisation with a dual-module mesoporous and microporous three-dimensional π-network in which surface-exposed nanoparticles are crystallised upon in situ reduction. The uncovered palladium nanoparticles serve as heterogeneous catalysts that are exceptionally active in water, catalyse unreactive aryl chlorides for straightforward carbon-carbon bond formation and are stable for repeated use in various types of cross couplings. Therefore, our results open new perspectives in developing practical heterogeneous catalysts.

  14. Direct Imaging of Single Plasmonic Metal Nanoparticles in Capillary with Laser Light-Sheet Scattering Imaging.

    PubMed

    Cao, Xuan; Feng, Jingjing; Pan, Qi; Xiong, Bin; He, Yan; Yeung, Edward S

    2017-03-07

    Understanding the heterogeneous distribution of the physical and chemical properties of plasmonic metal nanoparticles is fundamentally important to their basic and applied research. Traditionally, they are obtained either indirectly via bulk spectroscopic measurements plus electron microscopic characterizations or through single molecule/particle imaging of nanoparticles immobilized on planar substrates. In this study, by using light-sheet scattering microscopy with a supercontinuum white laser, highly sensitive imaging of individual metal nanoparticles (MNPs) flowing inside a capillary, driven by either pressure or electric field, was achieved for the first time. We demonstrate that single plasmonic nanoparticles with different size or chemical modification could be differentiated through their electrophoretic mobility in a few minutes. This technique could potentially be applied to high throughput characterization and evaluation of single metal nanoparticles as well as their dynamic interactions with various local environments.

  15. Extraordinary Light-Induced Local Angular Momentum near Metallic Nanoparticles.

    PubMed

    Alabastri, Alessandro; Yang, Xiao; Manjavacas, Alejandro; Everitt, Henry O; Nordlander, Peter

    2016-04-26

    The intense local field induced near metallic nanostructures provides strong enhancements for surface-enhanced spectroscopies, a major focus of plasmonics research over the past decade. Here we consider that plasmonic nanoparticles can also induce remarkably large electromagnetic field gradients near their surfaces. Sizeable field gradients can excite dipole-forbidden transitions in nearby atoms or molecules and provide unique spectroscopic fingerprinting for chemical and bimolecular sensing. Specifically, we investigate how the local field gradients near metallic nanostructures depend on geometry, polarization, and wavelength. We introduce the concept of the local angular momentum (LAM) vector as a useful figure of merit for the design of nanostructures that provide large field gradients. This quantity, based on integrated fields rather than field gradients, is particularly well-suited for optimization using numerical grid-based full wave electromagnetic simulations. The LAM vector has a more compact structure than the gradient matrix and can be straightforwardly associated with the angular momentum of the electromagnetic field incident on the plasmonic structures.

  16. Condensation Dynamics on Mimicked Metal Matrix Hydrophobic Nanoparticle-Composites

    NASA Astrophysics Data System (ADS)

    Damle, Viraj; Sun, Xiaoda; Rykaczewski, Konrad

    2014-11-01

    Use of hydrophobic surfaces promotes condensation in the dropwise mode, which is significantly more efficient than the common filmwise mode. However, limited longevity of hydrophobic surface modifiers has prevented their wide spread use in industry. Recently, metal matrix composites (MMCs) having microscale hydrophobic heterogeneities dispersed in hydrophilic metal matrix have been proposed as durable and self-healing alternative to hydrophobic surface coatings interacting with deposited water droplets. While dispersion of hydrophobic microparticles in MMC is likely to lead to surface flooding during condensation, the effect of dispersion of hydrophobic nanoparticles (HNPs) with size comparable to water nuclei critical radii and spacing is not obvious. To this end, we fabricated highly ordered arrays of Teflon nanospheres on silicon substrates that mimic the top surface of the MMCs with dispersed HNPs. We used light and electron microscopy to observe breath figures resulting from condensation on these surfaces at varied degrees of subcooling. Here, we discuss the relation between the droplet size distribution, Teflon nanosphere diameter and spacing, and condensation mode. KR acknowledges startup funding from ASU.

  17. Optical properties and circular dichroism of chiral metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Fan, Zhiyuan; Govorov, Alexander; OU Team

    2013-03-01

    In nature, biological systems are built up by homochiral building blocks, such as a sugar and protein. Circular dichroism (CD) is an effective tool of resolving molecular conformations. It utilizes circularly polarized light to detect differential absorption of chiral materials. In medicine, it will help us to develop new drugs and therapies, if we understand the connection between the physical or chemical properties of drug molecules and their conformations. With the rapid development of nanotechnologies, chiral nanomaterials attract lots of attention nowadays. CD signals of chiral molecules can be enhanced or shifted to the visible band in the presence of plasmonic nanocrystals. Here we present a plasmonic CD mechanism from a single chiral metal nanocrystal. The mechanism is essentially different from the dipolar plasmon-plasmon interaction in a chiral NP assembly, which mimics the CD mechanism of chiral molecules. Chiral metal nanocrystals are expected to have promising applications in biosensing. Recently a few experimental papers reported successful realizations of chiral nanocrystals in a macroscopic ensemble in solution. Particularly the paper described silver nanoparticles grown on chiral template molecules and demonstrating characteristic CD signals at a plasmonic wavelength. The plasmonic CD signals in Ref. can come from a dipolar plasmon-molecule interaction or from a chiral shape of nanocrystals. This work was supported by the NSF (project: CBET- 0933782) and by the Volkswagen Foundation.

  18. Metallic nanoparticles in a standing wave: Optical force and heating

    NASA Astrophysics Data System (ADS)

    Šiler, Martin; Chvátal, Lukáš; Zemánek, Pavel

    2013-09-01

    We have investigated the absorbed power in a single gold or silver metallic nanoparticle together with the optical force acting upon it if the particle is illuminated by two counter-propagating plane waves forming a standing wave. We have used the Generalized Lorenz-Mie theory (GLMT) and considered the incident wavelengths 250nm≤λvac≤1250nm and particles size parameter 0.1≤d/λvac≤4. Similarly as in the case of dielectric particle we have found that the optical force is equal to zero for all particle positions in the standing wave for certain wavelengths and particle sizes. However, in the case of a metallic object this phenomenon occurs for considerably smaller particles and the conditions change considerably with the illuminating wavelength especially near the localized surface plasmon resonances. Similarly, we have found that the absorbed heat does not change with the position of the particle in the standing wave for certain wavelengths and particle sizes. These sizes generally differ from those giving zero optical force and, therefore, the particle can be trapped at the intensity maximum or minimum and in both cases its heating is maximal or minimal depending on the particle size.

  19. Magnesium nanoparticles with transition metal decoration for hydrogen storage

    NASA Astrophysics Data System (ADS)

    Pasquini, Luca; Callini, Elsa; Brighi, Matteo; Boscherini, Federico; Montone, Amelia; Jensen, Torben R.; Maurizio, Chiara; Vittori Antisari, Marco; Bonetti, Ennio

    2011-11-01

    We report on the hydrogen storage behaviour of Mg nanoparticles (NPs) (size range 100 nm-1 μm) with metal-oxide core-shell morphology synthesized by inert gas condensation and decorated by transition metal (TM) (Pd or Ti) clusters via in situ vacuum deposition. The structure and morphology of the as-prepared and hydrogenated NPs is studied by electron microscopy, X-ray diffraction including in situ experiments and X-ray absorption spectroscopy, in order to investigate the relationships with the hydrogen storage kinetics measured by the volumetric Sieverts method. With both Pd and Ti, the decoration deeply improves the hydrogen sorption properties: previously inert NPs exhibit complete hydrogenation with fast transformation kinetics, good stability and reversible gravimetric capacity that can attain 6 wt%. In the case of Pd-decoration, the occurrence of Mg-Pd alloying is observed at high temperatures and in dependence of the hydrogen pressure conditions. These structural transformations modify both the kinetics and thermodynamics of hydride formation, while Ti-decoration has an effect only on the kinetics. The experimental results are discussed in relation with key issues such as the amount of decoration, the heat of mixing between TM and Mg and the binding energy between TM and hydrogen.

  20. Carbon nanomaterials combined with metal nanoparticles for theranostic applications

    PubMed Central

    Modugno, Gloria; Ménard-Moyon, Cécilia; Prato, Maurizio; Bianco, Alberto

    2015-01-01

    Among targeted delivery systems, platforms with nanosize dimensions, such as carbon nanomaterials (CNMs) and metal nanoparticles (NPs), have shown great potential in biomedical applications. They have received considerable interest in recent years, especially with respect to their potential utilization in the field of cancer diagnosis and therapy. The many functions of nanomaterials provide opportunities to use them as multimodal agents for theranostics, a combination of therapy and diagnosis. Carbon nanotubes and graphene are some of the most widely used CNMs because of their unique structural and physicochemical properties. Their high specific surface area allows for efficient drug loading and the possibility of functionalization with various bioactive molecules. In addition, CNMs are ideal platforms for the attachment of NPs. In the biomedical field, NPs have also shown tremendous potential for use in drug delivery, non-invasive tumour imaging and early detection due to their optical and magnetic properties. NP/CNM hybrids not only combine the unique properties of the NPs and CNMs but they also exhibit new properties arising from interactions between the two entities. In this review, the preparation of CNMs conjugated to different types of metal NPs and their applications in diagnosis, imaging, therapy and theranostics are presented. PMID:25323135

  1. Core-satellites assembly of silver nanoparticles on a single gold nanoparticle via metal ion-mediated complex.

    PubMed

    Choi, Inhee; Song, Hyeon Don; Lee, Suseung; Yang, Young In; Kang, Taewook; Yi, Jongheop

    2012-07-25

    We report core-satellites (Au-Ag) coupled plasmonic nanoassemblies based on bottom-up, high-density assembly of molecular-scale silver nanoparticles on a single gold nanoparticle surface, and demonstrate direct observation and quantification of enhanced plasmon coupling (i.e., intensity amplification and apparent spectra shift) in a single particle level. We also explore metal ion sensing capability based on our coupled plasmonic core-satellites, which enabled at least 1000 times better detection limit as compared to that of a single plasmonic nanoparticle. Our results demonstrate and suggest substantial promise for the development of coupled plasmonic nanostructures for ultrasensitive detection of various biological and chemical analytes.

  2. Excitation enhancement of CdSe quantum dots by single metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Chen, Yeechi; Munechika, Keiko; Jen-La Plante, Ilan; Munro, Andrea M.; Skrabalak, Sara E.; Xia, Younan; Ginger, David S.

    2008-08-01

    We study plasmon-enhanced fluorescence from CdSe /CdS/CdZnS/ZnS core/shell quantum dots near a variety of Ag and Au nanoparticles. The photoluminescence excitation (PLE) spectrum of quantum dots closely follows the localized surface plasmon resonance (LSPR) scattering spectrum of the nanoparticles. We measure excitation enhancement factors of ˜3 to 10 for different shapes of single metal nanoparticles.

  3. Adherent diamond like carbon coatings on metals via plasma source ion implantation

    SciTech Connect

    Walter, K.C.; Nastasi, M.; Munson, C.P.

    1996-12-01

    Various techniques are currently used to produce diamond-like carbon (DLC) coatings on various materials. Many of these techniques use metallic interlayers, such as Ti or Si, to improve the adhesion of a DLC coating to a ferrous substrate. An alternative processing route would be to use plasma source ion implantation (PSII) to create a carbon composition gradient in the surface of the ferrous material to serve as the interface for a DLC coating. The need for interlayer deposition is eliminated by using a such a graded interfaces PSII approach has been used to form adherent DLC coatings on magnesium, aluminum, silicon, titanium, chromium, brass, nickel, and tungsten. A PSII process tailored to create a graded interface allows deposition of adherent DLC coatings even on metals that exhibit a positive heat of formation with carbon, such as magnesium, iron, brass and nickel.

  4. Nonaqueous synthesis of metal oxide nanoparticles: Short review and doped titanium dioxide as case study for the preparation of transition metal-doped oxide nanoparticles

    SciTech Connect

    Djerdj, Igor Arcon, Denis; Jaglicic, Zvonko; Niederberger, Markus

    2008-07-15

    The liquid-phase synthesis of metal oxide nanoparticles in organic solvents under exclusion of water is nowadays a well-established alternative to aqueous sol-gel chemistry. In this article, we highlight some of the advantages of these routes based on selected examples. The first part reviews some recent developments in the synthesis of ternary metal oxide nanoparticles by surfactant-free nonaqueous sol-gel routes, followed by the discussion of the morphology-controlled synthesis of lanthanum hydroxide nanoparticles, and the presentation of structural peculiarities of manganese oxide nanoparticles with an ordered Mn vacancy superstructure. These examples show that nonaqueous systems, on the one hand, allow the preparation of compositionally complex oxides, and, on the other hand, make use of the organic components (initially present or formed in situ) in the reaction mixture to tailor the morphology. Furthermore, obviously even the crystal structure can differ from the corresponding bulk material like in the case of MnO nanoparticles. In the second part of the paper we present original results regarding the synthesis of dilute magnetic semiconductor TiO{sub 2} nanoparticles doped with cobalt and iron. The structural characterization as well as the magnetic properties with special attention to the doping efficiency is discussed. - Graphical abstract: In the first part of this article, nonaqueous sol-gel routes to ternary metal oxide nanoparticles are briefly reviewed, followed by the discussion of the morphology-controlled synthesis of lanthanum hydroxide nanoparticles, and the appearance of an unprecedented superstructure in MnO nanoparticles. In the second part, doping experiments of TiO{sub 2} with Fe and Co are presented, along with their characterization including magnetic measurements.

  5. Fabrication of highly transparent Al-ion-implanted ZnO thin films by metal vapor vacuum arc method

    NASA Astrophysics Data System (ADS)

    Lee, Han; Sivashanmugan, Kundan; Kao, Chi-Yuan; Liao, Jiunn-Der

    2017-03-01

    In this study, we utilized the metal vapor vacuum arc technique to implant vaporized aluminum (Al) ions in zinc oxide (ZnO) thin films. By adjusting the ion implantation dose and operational parameters, the conductivity and optical properties of the ZnO thin film can be controlled. The electrical sheet resistance of Al-ion-implanted ZnO decreased from 3.02 × 107 to 3.03 × 104 Ω/sq, while the transparency of the film was mostly preserved (91.5% at a wavelength of 550 nm). The ZnO thin-film Young’s modulus significantly increased with increasing Al ion dose.

  6. A Bioanalytical Chemistry Experiment for Undergraduate Students: Biosensors Based on Metal Nanoparticles

    ERIC Educational Resources Information Center

    Niagi, John; Warner, John; Andreesco, Silvana

    2007-01-01

    The study describes the development of new biosensors based on metal nanoparticles because of its high surface area and large binding ability. The adopted procedure is extremely simple and versatile and can be used in various applications of electrochemistry.

  7. Simultaneously photodeposited rhodium metal and oxide nanoparticles promoting photocatalytic hydrogen production.

    PubMed

    Shimura, Katsuya; Kawai, Hiromasa; Yoshida, Tomoko; Yoshida, Hisao

    2011-08-21

    Photodeposition of a Rh cocatalyst under atmospheric conditions could simultaneously provide both Rh metal and oxide nanoparticles on a K(2)Ti(6)O(13) photocatalyst, both of which cooperatively promoted the photocatalytic hydrogen production from water and methane.

  8. Metal nanoparticles (other than gold or silver) prepared using plant extracts for medical applications

    NASA Astrophysics Data System (ADS)

    Pasca, Roxana-Diana; Santa, Szabolcs; Racz, Levente Zsolt; Racz, Csaba Pal

    2016-12-01

    There are many modalities to prepare metal nanoparticles, but the reducing of the metal ions with plant extracts is one of the most promising because it is considerate less toxic for the environment, suitable for the use of those nanoparticles in vivo and not very expensive. Various metal ions have been already studied such as: cobalt, copper, iron, platinum, palladium, zinc, indium, manganese and mercury and the number of plant extracts used is continuously increasing. The prepared systems were characterized afterwards with a great number of methods of investigation: both spectroscopic (especially UV-Vis spectroscopy) and microscopic (in principal, electron microscopy-TEM) methods. The applications of the metal nanoparticles obtained are diverse and not completely known, but the medical applications of such nanoparticles occupy a central place, due to their nontoxic components, but some diverse industrial applications do not have to be forgotten.

  9. Effect of Percolation on the Cubic Susceptibility of Metal Nanoparticle Composites

    NASA Technical Reports Server (NTRS)

    Smith, David D.; Bender, Matthew W.; Boyd, Robert W.

    1998-01-01

    Generalized two-dimensional and three-dimensional Maxwell Garnett and Bruggeman geometries reveal that a sign reversal in the cubic susceptibility occurs for metal nanoparticle composites near the percolation threshold.

  10. Green synthesis of metal nanoparticles: biodegradable polymers and enzymes in stabilization and surface functionalization

    EPA Science Inventory

    Current breakthroughs in green nanotechnology are capable to transform many of the existing processes and products that enhance environmental quality, reduce pollution, and conserve natural and non-renewable resources. Noteworthy, successful use of metal nanoparticles and 10 nano...

  11. Electrocatalytic reduction of carbon dioxide on post-transition metal and metal oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    White, James L.

    The electroreduction of carbon dioxide to liquid products is an important component in the utilization of CO2 and in the high-density storage of intermittent renewable energy in the form of chemical bonds. Materials based on indium and tin, which yield predominantly formic acid, have been investigated in order to gain a greater understanding of the electrochemically active species and the mechanism of CO2 reduction on these heavy post-transition metals, since prior studies on the bulk metals did not provide thermodynamically sensible reaction pathways. Nanoparticles of the oxides and hydroxides of tin and indium have been prepared and characterized by transmission electron microscopy, X-ray diffractometry, X-ray photoelectron spectroscopy, and various electrochemical methods in order to obtain structural information and analyze the role of various surface species on the CO2 reduction pathway. On both indium and tin, metastable surface-bound hydroxides bound CO2 and formed metal carbonates, which can then be reduced electrochemically. The relevant oxidation state of tin was suggested to be SnII rather than SnIV, necessitating a pre reduction to generate the CO2-binding species. Metallic indium nanoparticles partially oxidized in air and became highly efficient CO2 reduction electrocatalysts. Unit Faradaic efficiencies for formate, much higher than on bulk indium, were achieved with only 300 mV of overpotential on these particles, which possessed an oxyhydroxide shell surrounding a conductive metallic core. Alloys and mixed-metal oxide and hydroxide particles of tin and indium have also been studied for their carbon dioxide electrocatalytic capabilities, especially in comparison to the pure metal species. Additionally, a solar-driven indium-based CO2 electrolyzer was developed to investigate the overall efficiency for intermittent energy storage. The three flow cells were powered by a commercial photovoltaic array and had a maximum conversion efficiency of incident

  12. Metal nanoparticle deposited inorganic nanostructure hybrids, uses thereof and processes for their preparation

    DOEpatents

    Tenne, Reshef; Tsverin, Yulia; Burghaus, Uwe; Komarneni, Mallikharjuna Rao

    2016-01-26

    This invention relates to a hybrid component comprising at least one nanoparticle of inorganic layered compound (in the form of fullerene-like structure or nanotube), and at least one metal nanoparticle, uses thereof as a catalyst, (e.g. photocatalysis) and processes for its preparation.

  13. Biomimetic Synthesis of Gelatin Polypeptide-Assisted Noble-Metal Nanoparticles and Their Interaction Study

    NASA Astrophysics Data System (ADS)

    Liu, Ying; Liu, Xiaoheng; Wang, Xin

    2011-12-01

    Herein, the generation of gold, silver, and silver-gold (Ag-Au) bimetallic nanoparticles was carried out in collagen (gelatin) solution. It first showed that the major ingredient in gelatin polypeptide, glutamic acid, acted as reducing agent to biomimetically synthesize noble metal nanoparticles at 80°C. The size of nanoparticles can be controlled not only by the mass ratio of gelatin to gold ion but also by pH of gelatin solution. Interaction between noble-metal nanoparticles and polypeptide has been investigated by TEM, UV-visible, fluorescence spectroscopy, and HNMR. This study testified that the degradation of gelatin protein could not alter the morphology of nanoparticles, but it made nanoparticles aggregated clusters array (opposing three-dimensional α-helix folding structure) into isolated nanoparticles stabilized by gelatin residues. This is a promising merit of gelatin to apply in the synthesis of nanoparticles. Therefore, gelatin protein is an excellent template for biomimetic synthesis of noble metal/bimetallic nanoparticle growth to form nanometer-sized device.

  14. Alkylamine capped metal nanoparticle "inks" for printable SERS substrates, electronics and broadband photodetectors.

    PubMed

    Polavarapu, Lakshminarayana; Manga, Kiran Kumar; Yu, Kuai; Ang, Priscilla Kailian; Cao, Hanh Duyen; Balapanuru, Janardhan; Loh, Kian Ping; Xu, Qing-Hua

    2011-05-01

    We report a facile and general method for the preparation of alkylamine capped metal (Au and Ag) nanoparticle "ink" with high solubility. Using these metal nanoparticle "inks", we have demonstrated their applications for large scale fabrication of highly efficient surface enhanced Raman scattering (SERS) substrates by a facile solution processing method. These SERS substrates can detect analytes down to a few nM. The flexible plastic SERS substrates have also been demonstrated. The annealing temperature dependent conductivity of the nanoparticle films indicated a transition temperature above which high conductivity was achieved. The transition temperature could be tailored to the plastic compatible temperatures by using proper alkylamine as the capping agent. The ultrafast electron relaxation studies of the nanoparticle films demonstrated that faster electron relaxation was observed at higher annealing temperatures due to stronger electronic coupling between the nanoparticles. The applications of these highly concentrated alkylamine capped metal nanoparticle inks for the printable electronics were demonstrated by printing the oleylamine capped gold nanoparticles ink as source and drain for the graphene field effect transistor. Furthermore, the broadband photoresponse properties of the Au and Ag nanoparticle films have been demonstrated by using visible and near-infrared lasers. These investigations demonstrate that these nanoparticle "inks" are promising for applications in printable SERS substrates, electronics, and broadband photoresponse devices.

  15. Brief ultrasonication improves detection of biofilm-formative bacteria around a metal implant.

    PubMed

    Kobayashi, Naomi; Bauer, Thomas W; Tuohy, Marion J; Fujishiro, Takaaki; Procop, Gary W

    2007-04-01

    Biofilms are complex microenvironments produced by microorganisms on surfaces. Ultrasonication disrupts biofilms and may make the microorganism or its DNA available for detection. We determined whether ultrasonication could affect our ability to detect bacteria adherent to a metal substrate. A biofilm-formative Staphylococcus aureus strain was used for an in vitro implant infection model (biofilm-formative condition). We used quantitative culture and real time-polymerase chain reaction to determine the influence of different durations of ultrasound on bacterial adherence and viability. Sonication for 1 minute increased the yield of bacteria. Sonication longer than 5 minutes led to fewer bacterial colonies by conventional culture but not by polymerase chain reaction. This suggests short periods of sonication help release bacteria from the metal substrate by disrupting the biofilm, but longer periods of sonication lyse bacteria prohibiting their detection in microbiologic cultures. A relatively short duration of sonication may be desirable for maximizing detection of biofilm-formative bacteria around implants by culture or polymerase chain reaction.

  16. Assessment of the genetic risks of a metallic alloy used in medical implants

    PubMed Central

    Gomes, Cristiano C.; Moreira, Leonardo M.; Santos, Vanessa J.S.V.; Ramos, Alfeu S.; Lyon, Juliana P.; Soares, Cristina P.; Santos, Fabio V.

    2011-01-01

    The use of artificial implants provides a palliative or permanent solution for individuals who have lost some bodily function through disease, an accident or natural wear. This functional loss can be compensated for by the use of medical devices produced from special biomaterials. Titanium alloy (Ti-6Al-4V) is a well-established primary metallic biomaterial for orthopedic implants, but the toxicity of the chemical components of this alloy has become an issue of concern. In this work, we used the MTT assay and micronucleus assay to examine the cytotoxicity and genotoxicity, respectively, of an extract obtained from this alloy. The MTT assay indicated that the mitochondrial activity and cell viability of CHO-K1 cells were unaffected by exposure to the extract. However, the micronucleus assay revealed DNA damage and an increase in micronucleus frequency at all of the concentrations tested. These results show that ions released from Ti-6Al-4V alloy can cause DNA and nuclear damage and reinforce the importance of assessing the safety of metallic medical devices constructed from biomaterials. PMID:21637553

  17. Similar Success Rates with Bivalirudin and Unfractionated Heparin in Bare-Metal Stent Implantation

    SciTech Connect

    Hallak, Omar; Shams, S. Ali; Broce, Mike; Lavigne, P. Scott; Lucas, B. Daniel; Elhabyan, Abdul-Karim; Reyes, Bernardo J.

    2007-09-15

    Background. Unfractionated heparin (UFH) is the traditional agent utilized during percutaneous peripheral interventions (PPIs) despite its well-known limitations. Bivalirudin, a thrombin-specific anticoagulant, overcomes many of the limitations of UFH and has consistently demonstrated comparable efficacy with significantly fewer bleeding complications. The purpose of this study was to compare procedural success in patients undergoing bare-metal stent implantation for atherosclerotic blockage of the renal, iliac, and femoral arteries and receiving either bivalirudin (0.75 mg/kg bolus/1.75 mg/kg/hr infusion) or UFH (50-70 U/kg/hr bolus) as the primary anticoagulant. Methods. This study was an open-label, nonrandomized retrospective registry with the primary endpoint of procedural success. Secondary endpoints included incidence of: death, myocardial infarction (MI), urgent revascularization, amputation, and major and minor bleeding. Results. One hundred and five consecutive patients were enrolled (bivalirudin = 53; heparin = 52). Baseline demographics were comparable between groups. Patients were pretreated with clopidogrel (approx. 71%) and aspirin (approx. 79%). Procedural success was achieved in 97% and 96% of patients in the bivalirudin- and heparin-treated groups, respectively. Event rates were low and similar between groups. Conclusion. Bivalirudin maintained an equal rate of procedural success in this cohort without sacrificing patient safety. Results of this study add to the growing body of evidence supporting the safety and efficacy of bivalirudin as a possible substitute for UFH in anticoagulation during peripheral vascular bare-metal stent implantation.

  18. Direct-Contact Low-Frequency Ultrasound Clearance of Biofilm From Metallic Implant Materials.

    PubMed

    Granick, Mark S; Paribathan, Chaitra; Shanmugam, Mayilvahanan; Ramasubbu, Narayanan

    2017-01-01

    Introduction: Biofilms are recognized as a significant deterrent to wound healing and to the management of exposed or infected surgical implants. Biofilms can be disrupted by a variety of enzymatic and mechanical interventions. This experiment was designed to determine whether direct-contact low-frequency ultrasound has the ability to clear biofilms and what then happens to the released bacteria. Methods:Staphylococcus epidermidis biofilm was grown on the surfaces of metallic discs composed of titanium and stainless steel, comparable with the alloys used in surgical implants. The discs were treated with a control of irrigation and no ultrasound, followed by the ultrasound for a 10 second of exposure at a mid-level power setting. The irrigation materials used was either normal saline or hypochlorous acid. The effluent was cultured to determine colony-forming units, and the discs were stained with crystal violet to determine whether there was a residual biofilm. Results: The biofilm was cleared completely from all discs when treated with direct-contact low-frequency ultrasound. However, the released bacteria were viable and could be cultured from the effluent when saline was used as the irrigation medium. When hypochlorous acid was used as the irrigation medium, there was complete killing of all planktonic bacteria. Conclusion: Direct-contact low-frequency ultrasound is effective when used to clear biofilms from metallic implant materials. By using hypochlorous acid as the irrigant during treatment, all of the bacteria released from the biofilm were killed as well. The implications for clinical application are important and need to be independently studied.

  19. The Effects of Metallic Implants on Electroporation Therapies: Feasibility of Irreversible Electroporation for Brachytherapy Salvage

    SciTech Connect

    Neal, Robert E.; Smith, Ryan L.; Kavnoudias, Helen; Rosenfeldt, Franklin Ou, Ruchong; Mclean, Catriona A.; Davalos, Rafael V.; Thomson, Kenneth R.

    2013-12-15

    Purpose: Electroporation-based therapies deliver brief electric pulses into a targeted volume to destabilize cellular membranes. Nonthermal irreversible electroporation (IRE) provides focal ablation with effects dependent on the electric field distribution, which changes in heterogeneous environments. It should be determined if highly conductive metallic implants in targeted regions, such as radiotherapy brachytherapy seeds in prostate tissue, will alter treatment outcomes. Theoretical and experimental models determine the impact of prostate brachytherapy seeds on IRE treatments. Materials and Methods: This study delivered IRE pulses in nonanimal, as well as in ex vivo and in vivo tissue, with and in the absence of expired radiotherapy seeds. Electrical current was measured and lesion dimensions were examined macroscopically and with magnetic resonance imaging. Finite-element treatment simulations predicted the effects of brachytherapy seeds in the targeted region on electrical current, electric field, and temperature distributions. Results: There was no significant difference in electrical behavior in tissue containing a grid of expired radiotherapy seeds relative to those without seeds for nonanimal, ex vivo, and in vivo experiments (all p > 0.1). Numerical simulations predict no significant alteration of electric field or thermal effects (all p > 0.1). Histology showed cellular necrosis in the region near the electrodes and seeds within the ablation region; however, there were no seeds beyond the ablation margins. Conclusion: This study suggests that electroporation therapies can be implemented in regions containing small metallic implants without significant changes to electrical and thermal effects relative to use in tissue without the implants. This supports the ability to use IRE as a salvage therapy option for brachytherapy.

  20. Direct-Contact Low-Frequency Ultrasound Clearance of Biofilm From Metallic Implant Materials

    PubMed Central

    Paribathan, Chaitra; Shanmugam, Mayilvahanan; Ramasubbu, Narayanan

    2017-01-01

    Introduction: Biofilms are recognized as a significant deterrent to wound healing and to the management of exposed or infected surgical implants. Biofilms can be disrupted by a variety of enzymatic and mechanical interventions. This experiment was designed to determine whether direct-contact low-frequency ultrasound has the ability to clear biofilms and what then happens to the released bacteria. Methods: Staphylococcus epidermidis biofilm was grown on the surfaces of metallic discs composed of titanium and stainless steel, comparable with the alloys used in surgical implants. The discs were treated with a control of irrigation and no ultrasound, followed by the ultrasound for a 10 second of exposure at a mid-level power setting. The irrigation materials used was either normal saline or hypochlorous acid. The effluent was cultured to determine colony-forming units, and the discs were stained with crystal violet to determine whether there was a residual biofilm. Results: The biofilm was cleared completely from all discs when treated with direct-contact low-frequency ultrasound. However, the released bacteria were viable and could be cultured from the effluent when saline was used as the irrigation medium. When hypochlorous acid was used as the irrigation medium, there was complete killing of all planktonic bacteria. Conclusion: Direct-contact low-frequency ultrasound is effective when used to clear biofilms from metallic implant materials. By using hypochlorous acid as the irrigant during treatment, all of the bacteria released from the biofilm were killed as well. The implications for clinical application are important and need to be independently studied.

  1. Biotests and Biosensors for Ecotoxicology of Metal Oxide Nanoparticles: A Minireview.

    PubMed

    Kahru, Anne; Dubourguier, Henri-Charles; Blinova, Irina; Ivask, Angela; Kasemets, Kaja

    2008-08-28

    Nanotechnologies have become a significant priority worldwide. Several manufactured nanoparticles - particles with one dimension less than 100 nm - are increasingly used in consumer products. At nanosize range, the properties of materials differ substantially from bulk materials of the same composition, mostly due to the increased specific surface area and reactivity, which may lead to increased bioavailability and toxicity. Thus, for the assessment of sustainability of nanotechnologies, hazards of manufactured nanoparticles have to be studied. Despite all the above mentioned, the data on the potential environmental effects of nanoparticles are rare. This mini-review is summarizing the emerging information on different aspects of ecotoxicological hazard of metal oxide nanoparticles, focusing on TiO₂, ZnO and CuO. Various biotests that have been successfully used for evaluation of ecotoxic properties of pollutants to invertebrates, algae and bacteria and now increasingly applied for evaluation of hazard of nanoparticles at different levels of the aquatic food-web are discussed. Knowing the benefits and potential drawbacks of these systems, a suite of tests for evaluation of environmental hazard of nanoparticles is proposed. Special attention is paid to the influence of particle solubility and to recombinant metal-sensing bacteria as powerful tools for quantification of metal bioavailability. Using recombinant metal-specific bacterial biosensors and multitrophic ecotoxicity assays in tandem will create new scientific knowledge on the respective role of ionic species and of particles in toxicity of metal oxide nanoparticles.

  2. Biotests and Biosensors for Ecotoxicology of Metal Oxide Nanoparticles: A Minireview

    PubMed Central

    Kahru, Anne; Dubourguier, Henri-Charles; Blinova, Irina; Ivask, Angela; Kasemets, Kaja

    2008-01-01

    Nanotechnologies have become a significant priority worldwide. Several manufactured nanoparticles - particles with one dimension less than 100 nm - are increasingly used in consumer products. At nanosize range, the properties of materials differ substantially from bulk materials of the same composition, mostly due to the increased specific surface area and reactivity, which may lead to increased bioavailability and toxicity. Thus, for the assessment of sustainability of nanotechnologies, hazards of manufactured nanoparticles have to be studied. Despite all the above mentioned, the data on the potential environmental effects of nanoparticles are rare. This mini-review is summarizing the emerging information on different aspects of ecotoxicological hazard of metal oxide nanoparticles, focusing on TiO2, ZnO and CuO. Various biotests that have been successfully used for evaluation of ecotoxic properties of pollutants to invertebrates, algae and bacteria and now increasingly applied for evaluation of hazard of nanoparticles at different levels of the aquatic food-web are discussed. Knowing the benefits and potential drawbacks of these systems, a suite of tests for evaluation of environmental hazard of nanoparticles is proposed. Special attention is paid to the influence of particle solubility and to recombinant metal-sensing bacteria as powerful tools for quantification of metal bioavailability. Using recombinant metal-specific bacterial biosensors and multitrophic ecotoxicity assays in tandem will create new scientific knowledge on the respective role of ionic species and of particles in toxicity of metal oxide nanoparticles. PMID:27873807

  3. Distributed Analysis of Hip Implants Using Six National and Regional Registries: Comparing Metal-on-Metal with Metal-on-Highly Cross-Linked Polyethylene Bearings in Cementless Total Hip Arthroplasty in Young Patients

    PubMed Central

    Furnes, Ove; Paxton, Elizabeth; Cafri, Guy; Graves, Stephen; Bordini, Barbara; Comfort, Thomas; Rivas, Moises Coll; Banerjee, Samprit; Sedrakyan, Art

    2014-01-01

    Background: The regulation of medical devices has attracted controversy recently because of problems related to metal-on-metal hip implants. There is growing evidence that metal-on-metal implants fail early and cause local and systemic complications. However, the failure associated with metal-on-metal head size is not consistently documented and needs to be communicated to patients and surgeons. The purpose of this study is to compare implant survival of metal on metal with that of metal on highly cross-linked polyethylene. Methods: Using a distributed health data network, primary total hip arthroplasties were identified from six national and regional total joint arthroplasty registries (2001 to 2010). Inclusion criteria were patient age of forty-five to sixty-four years, cementless total hip arthroplasties, primary osteoarthritis diagnosis, and exclusion of the well-known outlier implant ASR (articular surface replacement). The primary outcome was revision for any reason. A meta-analysis of survival probabilities was performed with use of a fixed-effects model. Metal-on-metal implants with a large head size of >36 mm were compared with metal-on-highly cross-linked polyethylene implants. Results: Metal-on-metal implants with a large head size of >36 mm were used in 5172 hips and metal-on-highly cross-linked polyethylene implants were used in 14,372 hips. Metal-on-metal total hip replacements with a large head size of >36 mm had an increased risk of revision compared with metal-on-highly cross-linked polyethylene total hip replacements with more than two years of follow-up, with no difference during the first two years after implantation. The results of the hazard ratios (and 95% confidence intervals) from the multivariable model at various durations of follow-up were 0.95 (0.74 to 1.23) at zero to two years (p = 0.698), 1.42 (1.16 to 1.75) at more than two years to four years (p = 0.001), 1.78 (1.45 to 2.19) at more than four years to six years (p < 0.001), and 2

  4. Synthesis and NMR characterization of ligand-capped metal and metal-oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Sharma, Ramesh

    Ligand-capped metal and metal-oxide nanoparticles (NPs) have some interesting and useful physical properties that are not present in their respective bulk materials. These properties are of research interest in many applications such as catalysis, drug delivery, biological imaging, and plasmonics. In such applications, it is critical to understand the surface structure of NPs and the roles played by the surface bound ligands. To characterize surface environment, ligand dynamics, and exchange kinetics, ligand-capped metal and metal-oxide NPs are synthesized and studied by multinuclear NMR. Phosphines and phosphonic acids are used to passivate metal (gold and silver) and metal-oxide (tin dioxide) NPs in different sizes (1-5 nm) by following published procedures or original synthesis methods. In both solution and solid state NMR, the 31P chemical shift of surface-bound ligands are distinctly different from those observed for free ligands. Additionally, NMR line widths in surface-bound ligands are highly broadened compared to those of free ligands. The lines are broadened due to both homogeneous and inhomogeneous broadening mechanisms, determined through hole burning NMR and spin-spin relaxation measurements. In small particles (< 2 nm), the main source of line broadening is inhomogeneous and originates due to structural heterogeneity and underlying chemical shift distributions. In large particles (> 2 nm), both inhomogeneous and homogeneous line broadening mechanisms are present. When the particles' sizes increase from small to large, the homogeneous broadening mechanism becomes dominant due to strong nuclear-electron interaction and reintroduction of residual dipolar coupling as shown by a combination of 1H, 13C and 31P NMR. Results from a series of ligand exchange experiments in silver and gold NPs further indicate the presence of Au(I) and Ag(I) on the particle surfaces.

  5. Hydrothermal synthesis of platinum-group-metal nanoparticles by using HEPES as a reductant and stabilizer.

    PubMed

    So, Man-Ho; Ho, Chi-Ming; Chen, Rong; Che, Chi-Ming

    2010-06-01

    Platinum-group-metal (Ru, Os, Rh, Ir, Pd and Pt) nanoparticles are synthesized in an aqueous buffer solution of 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) (200 mM, pH 7.4) under hydrothermal conditions (180 degrees C). Monodispersed (monodispersity: 11-15%) metal nanoparticles were obtained with an average particle size of less than 5 nm (Ru: 1.8+/-0.2, Os: 1.6+/-0.2, Rh: 4.5+/-0.5, Ir: 2.0+/-0.3, Pd: 3.8+/-0.4, Pt: 1.9+/-0.2 nm). The size, monodispersity, and stability of the as-obtained metal nanoparticles were affected by the HEPES concentration, pH of the HEPES buffer solution, and reaction temperature. HEPES with two tertiary amines (piperazine groups) and terminal hydroxyl groups can act as a reductant and stabilizer. The HEPES molecules can bind to the surface of metal nanoparticles to prevent metal nanoparticles from aggregation. These platinum-group-metal nanoparticles could be deposited onto the surface of graphite, which catalyzed the aerobic oxidation of alcohols to aldehydes.

  6. In vivo evaluation of an antibacterial coating containing halogenated furanone compound-loaded poly(l-lactic acid) nanoparticles on microarc-oxidized titanium implants

    PubMed Central

    Cheng, Yicheng; Gao, Bo; Liu, Xianghui; Zhao, Xianghui; Sun, Weige; Ren, Huifang; Wu, Jiang

    2016-01-01

    To prevent peri-implant infection, a new antibacterial coating containing a halogenated furanone compound, (Z-)-4-bromo-5-(bromomethylene)-2(5H)-furanone-loaded poly(l-lactic acid) nanoparticles, has been fabricated. The current study was designed to evaluate the preventive effect of the antibacterial coating under a simulated environment of peri-implant infection in vivo. Microarc-oxidized titanium implants treated with minocycline hydrochloride ointment were used as positive control group, and microarc-oxidized titanium implants without any treatment were used as blank control group. Three kinds of implants were implanted in dogs’ mandibles, and the peri-implant infection was simulated by silk ligation and feeding high sugar diet. After 2-month implantation, the results showed that no significant differences were detected between the experimental and positive control groups (P>0.05), but the data of clinical measurements of the blank control group were significantly higher than those of the other two groups (P<0.05), and the bone–implant contact rate and ultimate interfacial strength were significantly lower than those of the other two groups (P<0.05). Scanning electron microscope observation and histological examination showed that more new bone was formed on the surface of the experimental and positive control groups. It can be concluded that the antibacterial coating fabricated on implants has remarkable preventive effect on peri-implant infection at the early stage. PMID:27099494

  7. In vivo evaluation of an antibacterial coating containing halogenated furanone compound-loaded poly(l-lactic acid) nanoparticles on microarc-oxidized titanium implants.

    PubMed

    Cheng, Yicheng; Gao, Bo; Liu, Xianghui; Zhao, Xianghui; Sun, Weige; Ren, Huifang; Wu, Jiang

    2016-01-01

    To prevent peri-implant infection, a new antibacterial coating containing a halogenated furanone compound, (Z-)-4-bromo-5-(bromomethylene)-2(5H)-furanone-loaded poly(l-lactic acid) nanoparticles, has been fabricated. The current study was designed to evaluate the preventive effect of the antibacterial coating under a simulated environment of peri-implant infection in vivo. Microarc-oxidized titanium implants treated with minocycline hydrochloride ointment were used as positive control group, and microarc-oxidized titanium implants without any treatment were used as blank control group. Three kinds of implants were implanted in dogs' mandibles, and the peri-implant infection was simulated by silk ligation and feeding high sugar diet. After 2-month implantation, the results showed that no significant differences were detected between the experimental and positive control groups (P>0.05), but the data of clinical measurements of the blank control group were significantly higher than those of the other two groups (P<0.05), and the bone-implant contact rate and ultimate interfacial strength were significantly lower than those of the other two groups (P<0.05). Scanning electron microscope observation and histological examination showed that more new bone was formed on the surface of the experimental and positive control groups. It can be concluded that the antibacterial coating fabricated on implants has remarkable preventive effect on peri-implant infection at the early stage.

  8. Strong segregation gettering of transition metals by implantation-formed cavities and boron-silicide precipitates in silicon

    SciTech Connect

    Myers, S.M.; Petersen, G.A.; Follstaedt, D.M.; Headley, T.J.

    1996-06-01

    We have mechanistically and quantitatively characterized the binding of transition-metal impurities in Si to cavities formed by He implantation and to B-Si precipitates resulting from B implantation. Both sinks are inferred to act by the segregation of metal atoms to pre-existing low-energy sites, namely surface chemisorption sites in the case of cavities and bulk solution sites in the case of the B-Si phase. These gettering processes exhibit large binding energies, and they are predicted to remain active for arbitrarily small initial impurity concentrations as a result of the segregation mechanisms. Both appear promising for gettering in Si devices.

  9. Comparison of Whole-Blood Metal Ion Levels Among Four Types of Large-Head, Metal-on-Metal Total Hip Arthroplasty Implants: A Concise Follow-up, at Five Years, of a Previous Report.

    PubMed

    Hutt, Jonathan; Lavigne, Martin; Lungu, Eugen; Belzile, Etienne; Morin, François; Vendittoli, Pascal-André

    2016-02-17

    Few studies of total hip arthroplasty (THA) implants with a large-diameter femoral head and metal-on-metal design have directly compared the progression of metal ion levels over time and the relationship to complications. As we previously reported, 144 patients received one of four types of large-diameter-head, metal-on-metal THA designs (Durom, Birmingham, ASR XL, or Magnum implants). Cobalt, chromium, and titanium ion levels were measured over five years. We compared ion levels and clinical results over time. The Durom group showed the highest levels of cobalt (p ≤ 0.002) and titanium ions (p ≤ 0.03). Both the Durom and Birmingham groups demonstrated significant ongoing cobalt increases up to five years. Eight patients (seven with a Durom implant and one with a Birmingham implant) developed adverse local tissue reaction. Six Durom implants and one Birmingham implant required revision, with one pseudotumor under surveillance at the time of the most recent follow-up. We found that ion generation and related complications varied among designs. More concerning was that, for some designs, ion levels continued to increase. Coupling a cobalt-chromium adapter sleeve to an unmodified titanium femoral trunnion along with a large metal-on-metal bearing may explain the poor performances of two of the designs in the current study.

  10. Bio-related noble metal nanoparticle structure property relationships

    NASA Astrophysics Data System (ADS)

    Leonard, Donovan Nicholas

    Structure property relationships of noble metal nanoparticles (NPs) can be drastically different than bulk properties of the same metals. This research study used state-of-the-art analytical electron microscopy and scanned probe microscopy to determine material properties on the nanoscale of bio-related Au and Pd NPs. Recently, it has been demonstrated the self-assembly of Au NPs on functionalized silica surfaces creates a conductive surface. Determination of the aggregate morphology responsible for electron conduction was studied by atomic force microscopy (AFM) and scanning electron microscopy (SEM). In addition, changes in the electrical properties of the substrates after low temperature (<350°C) annealing was also studied. It was found that coalescence and densification of the Au NP aggregates disrupted the interconnected network which subsequently created a loss of conductivity. Investigation of bio-related Au/SiO2 core-shell NPs determined why published experimental results showed the sol-gel silica shell improved, by almost an order of magnitude, the detection efficiency of a DNA detection assay. Novel 360° rotation scanning TEM (STEM) imaging allowed study of individual NP surface morphology and internal structure. Electron energy loss spectroscopy (EELS) spectrum imaging determined optoelectronic properties and chemical composition of the silica shell used to encapsulate Au NPs. Results indicated the sol-gel deposited SiO2 had a band gap energy of ˜8.9eV, bulk plasmon-peak energy of ˜25.5eV and chemical composition of stoichiometric SiO2. Lastly, an attempt to elicit structure property relationships of novel RNA mediated Pd hexagon NPs was performed. Selected area electron diffraction (SAD), low voltage scanning transmission electron microscopy (LV-STEM), electron energy loss spectroscopy (EELS) and energy dispersive spectroscopy (EDS) were chosen for characterization of atomic ordering, chemical composition and optoelectronic properties of the novel

  11. Preparation of transition metal nanoparticles and surfaces modified with (CO) polymers synthesized by RAFT

    DOEpatents

    McCormick, III, Charles L.; Lowe, Andrew B.; Sumerlin, Brent S.

    2006-10-25

    A new, facile, general one-phase method of generating thiol-functionalized transition metal nanoparticles and surface modified by (co)polymers synthesized by the RAFT method is described. The method includes the steps of forming a (co)polymer in aqueous solution using the RAFT methodology, forming a collidal transition metal precursor solution from an appropriate transition metal; adding the metal precursor solution or surface to the (co)polymer solution, adding a reducing agent into the solution to reduce the metal colloid in situ to produce the stabilized nanoparticles or surface, and isolating the stabilized nanoparticles or surface in a manner such that aggregation is minimized. The functionalized surfaces generated using these methods can further undergo planar surface modifications, such as fuctionalization with a variety of different chemical groups, expanding their utility and application.

  12. Preparation of transition metal nanoparticles and surfaces modified with (co)polymers synthesized by RAFT

    DOEpatents

    McCormick, III, Charles L.; Lowe, Andrew B [Hattiesburg, MS; Sumerlin, Brent S [Pittsburgh, PA

    2011-12-27

    A new, facile, general one-phase method of generating thiol-functionalized transition metal nanoparticles and surfaces modified by (co)polymers synthesized by the RAFT method is described. The method includes the steps of forming a (co)polymer in aqueous solution using the RAFT methodology, forming a colloidal transition metal precursor solution from an appropriate transition metal; adding the metal precursor solution or surface to the (co)polymer solution, adding a reducing agent into the solution to reduce the metal colloid in situ to produce the stabilized nanoparticles or surface, and isolating the stabilized nanoparticles or surface in a manner such that aggregation is minimized. The functionalized surfaces generated using these methods can further undergo planar surface modifications, such as functionalization with a variety of different chemical groups, expanding their utility and application.

  13. Preparation of transition metal nanoparticles and surfaces modified with (CO)polymers synthesized by RAFT

    DOEpatents

    McCormick, III., Charles L.; Lowe, Andrew B.; Sumerlin, Brent S.

    2006-11-21

    A new, facile, general one-phase method of generating thio-functionalized transition metal nanoparticles and surfaces modified by (co)polymers synthesized by the RAFT method is described. The method includes the stops of forming a (co)polymer in aqueous solution using the RAFT methodology, forming a colloidal transition metal precursor solution from an appropriate transition metal; adding the metal precursor solution or surface to the (co)polymer solution, adding a reducing agent into the solution to reduce the metal colloid in situ to produce the stabilized nanoparticles or surface, and isolating the stabilized nanoparticles or surface in a manner such that aggregation is minimized. The functionalized surfaces generated using these methods can further undergo planar surface modifications, such as functionalization with a variety of different chemical groups, expanding their utility and application.

  14. Mesomorphic glass nanocomposites made of metal alkanoates and nanoparticles as emerging nonlinear-optical materials

    NASA Astrophysics Data System (ADS)

    Garbovskiy, Y.; Klimusheva, G.; Mirnaya, T.

    2016-09-01

    Mesomorphic metal alkanoates is very promising yet overlooked class of nonlinear-optical materials. Metal alkanoates can exhibit a broad variety of condensed states of matter including solid crystals, plastic crystals, lyotropic and thermotropic ionic liquid crystals, liquids, mesomorphic glasses, and Langmuir-Blodgett films. Glass-forming properties of metal alkanoates combined with their use as nano-reactors and anisotropic host open up simple and efficient way to design various photonic nanomaterials. Despite very interesting physics, the experimental data on optical and nonlinearoptical properties of such materials are scarce. The goal of the present paper is to fill the gap by discussing recent advances in the field of photonic materials made of metal alkanoates, organic dyes, and nanoparticles. Optical and nonlinear-optical properties of the following materials are reviewed: (i) mesomorphic glass doped with organic dyes; (ii) smectic glass composed of cobalt alkanoates; (iii) semiconductor nanoparticles embedded in a glassy host; (iv) metal nanoparticles - glass (the cobalt octanoate) nanocomposites.

  15. Structure and Optical Properties of Noble Metal Nanoparticles

    DTIC Science & Technology

    2012-08-29

    bare and passivated (thiolate-, phosphine-, or carboxylate-stabilized) gold and silver nanoparticles. The location of the ligands is responsible for...lowering. Nanoparticles, Nanowires, Gold, Silver , Thiolate, Phosphine, Carboxylate, Density Functional Theory, Time-Dependent Density Functional Theory...conditions under which gold and silver nanoparticles display broad/molecular or sharp surface plasmon resonance (SPR) optical absorption behavior. The

  16. Hollow nanoparticles of metal oxides and sulfides: fast preparation via laser ablation in liquid.

    PubMed

    Niu, K Y; Yang, J; Kulinich, S A; Sun, J; Du, X W

    2010-11-16

    In this work, diverse hollow nanoparticles of metal oxides and sulfides were prepared by simply laser ablating metal targets in properly chosen liquids. The Kirkendall voiding and the selective heating with an infrared laser were shown to work as two independent mechanisms for the formation of such hollow nanoparticles in only one- or two-step synthesis approaches. One of the prepared materials, ZnS hollow nanoparticles, showed high performance in gas sensing. The simple, fast, inexpensive technique that is proposed demonstrates very promising perspectives.

  17. Metal debris concentrations in soft tissues adjacent to loosened femoral stems is higher in uncemented than cemented implants

    PubMed Central

    2014-01-01

    Background There are still many questions related to aseptic femoral stem loosening. Systemic and local immune responses to the implanted “foreign body” is one of the reasons for loosening. The purpose of the study was to measure metal ion concentration (Ti, Co, Cr, Mo, Ni, Al) around loosened femoral stems and compare their levels around uncemented and cemented implants. Methods This paper reports 50 hips operated for isolated stem loosening, in 50 patients at the mean age of 57 years (from 21 to 87). There were 25 cemented (Co,Cr29,Mo,Ni) and 25 uncemented (Ti, Al) stems. The mean follow-up from primary hip replacement to revision was 10.1 years (from 0.5 to 17). During the procedure, scar tissue around the stem was taken for analysis of metal ions. Results The concentrations of titanium and aluminium in soft tissues around uncemented loosened stems were higher than cemented ones (p < 0.001, p < 0.001 respectively). However, no statistically significant differences were observed between both types of stems in terms of ions of the metal of which cemented implants had been made of (Co, Cr, Mo, Ni). Conclusions In soft tissue around a loosened stem, the concentrations of metal ions from implants are much higher in case of uncemented stems than of cemented ones. Metal ions from vitalium femoral heads were found around uncemented stems in similar values to cemented streams. PMID:25098913

  18. Accelerated Recovery of Endothelium Function after Stent Implantation with the Use of a Novel Systemic Nanoparticle Curcumin

    PubMed Central

    Lu, Qi; Ye, Fang; Yang, Xiangjun; Gu, Qingqing; Wang, Peng; Zhu, Jianhua; Shen, Li; Gong, Feirong

    2015-01-01

    Curcumin was reported to exhibit a wide range of pharmacological effects including antioxidant, anti-inflammatory, and antiproliferative activities and significantly prevent smooth muscle cells migration. In the present study, a novel kind of curcumin loaded nanoparticles (Cur-NP) has been prepared and characterized with the aim of inhibiting inflammation formation and accelerating the healing process of the stented arteries. Cur-NP was administrated intravenously after stent implantation twice a week and detailed tissue responses were evaluated. The results demonstrated that intravenous administration of Cur-NP after stent implantation accelerated endothelial cells restoration and endothelium function recovery and may potentially be an effective therapeutic alternative to reduce adverse events for currently available drug eluting stents. PMID:26167481

  19. N-Acetyl-Cysteine as Effective and Safe Chelating Agent in Metal-on-Metal Hip-Implanted Patients: Two Cases

    PubMed Central

    Lonati, Davide; Ragghianti, Benedetta; Ronchi, Anna; Vecchio, Sarah; Locatelli, Carlo Alessandro

    2016-01-01

    Systemic toxicity associated with cobalt (Co) and chromium (Cr) containing metal hip alloy may result in neuropathy, cardiomyopathy, and hypothyroidism. However clinical management concerning chelating therapy is still debated in literature. Here are described two metal-on-metal hip-implanted patients in which N-acetyl-cysteine decreased elevated blood metal levels. A 67-year-old male who underwent Co/Cr hip implant in September 2009 referred to our Poison Control Centre for persisting elevated Co/Cr blood levels (from March 2012 to November 2014). After receiving oral high-dose N-acetyl-cysteine, Co/Cr blood concentrations dropped by 86% and 87% of the prechelation levels, respectively, and persisted at these latter concentrations during the following 6 months of follow-up. An 81-year-old female who underwent Co/Cr hip implant in January 2007 referred to our Centre for detection of high Co and Cr blood levels in June 2012. No hip revision was indicated. After a therapy with oral high-dose N-acetyl-cysteine Co/Cr blood concentrations decreased of 45% and 24% of the prechelation levels. Chelating agents reported in hip-implanted patients (EDTA, DMPS, and BAL) are described in few cases. N-acetyl-cysteine may provide chelating sites for metals and in our cases reduced Co and Cr blood levels and resulted well tolerable. PMID:27148463

  20. Controlling plasmon coupling in biomolecule-linked metal nanoparticle assemblies

    NASA Astrophysics Data System (ADS)

    Sebba, David S.

    with DNA control of interparticle separation. Plasmon coupling is investigated also in binary metal systems. A new method for forming stable oligonucleotide-silver conjugates is presented, and controlled plasmon coupling is observed in reconfigurable core-satellite assemblies composed of 20 nm silver satellites linked to a 50 nm gold core by DNA tethers. Reconfiguration of the DNA linkers from a compact to an extended state results in decreased plasmon coupling and a blue-shift of the gold core plasmon resonance, similar to the response observed in analogous structures formed with gold satellites. Simulations of structures composed of gold and silver cores and satellites are performed to determine how the optical properties of binary metal assemblies may differ from those composed of a single metal. It appears that gold plasmons are systematically red shifted by silver particles, whereas plasmons supported by silver particles appear differentially sensitive to gold particles according to whether the silver particle is in a core position or a satellite shell. Next, the plasmonic properties of immobilized binary nanoparticle assemblies that incorporate a single strongly scattering component that acts as a template for assembly of weakly scattering plasmonic particles are investigated. Assemblies are composed of a streptavidin-coated gold "core" nanoparticle and BSA-biotin-coated gold or silver "satellite" particles. Through correlation of measured and simulated spectra, the dependence of assembly optical properties upon satellite coverage and satellite orientation about the core is addressed. It appears that plasmon coupling in gold core-gold satellite structures depends upon satellite orientation about the core and can manifest as either peak shifting or peak splitting, while the gold plasmon response to silver satellite assembly appears to be independent of satellite orientation. Finally, binary coupling is studied in one-dimensional particle pairs and three

  1. Facile synthesis of Curcuma longa tuber powder engineered metal nanoparticles for bioimaging applications

    NASA Astrophysics Data System (ADS)

    Sankar, Renu; Rahman, Pattanathu K. S. M.; Varunkumar, Krishnamoorthy; Anusha, Chidambaram; Kalaiarasi, Arunachalam; Shivashangari, Kanchi Subramanian; Ravikumar, Vilwanathan

    2017-02-01

    Nanomaterials based fluorescent agents are rapidly becoming significant and promising transformative tools for improving medical diagnostics for extensive in vivo imaging modalities. Compared with conventional fluorescent agents, nano-fluorescence has capabilities to improve the in vivo detection and enriched targeting efficiencies. In our laboratory we synthesized fluorescent metal nanoparticles of silver, copper and iron using Curcuma longa tuber powder by simple reduction. The physicochemical properties of the synthesized metal nanoparticles were attained using UV-visible spectrophotometry, scanning electron microscopy with EDAX spectroscopy, dynamic light scattering, Fourier-transform infrared spectroscopy and X-ray diffraction. The Curcuma longa tuber powder has one of the bioactive compound Curcumin might act as a capping agent during the synthesis of nanoparticles. The synthesized metal nanoparticles fluorescence property was confirmed by spectrofluorometry. When compared with copper and iron nanoparticles the silver nanoparticles showed high fluorescence intensity under spectrofluorometry. Moreover, in vitro cell images of the silver nanoparticles in A549 cell lines also correlated with the results of spectrofluorometry. These silver nanoparticles show inspiring cell-imaging applications. They enter into cells without any further modifications, and the fluorescence property can be utilized for fluorescence-based cell imaging applications.

  2. Carbon Materials Embedded with Metal Nanoparticles as Anode in Lithium-Ion Batteries

    NASA Technical Reports Server (NTRS)

    Hung, Ching-cheh

    2002-01-01

    Carbon materials containing metal nanoparticles that can form an alloy with lithium were tested for their capacity and cycle life to store and release lithium electrochemically. Metal nanoparticles may provide the additional lithium storage capacity as well as additional channels to conduct lithium in carbon. The cycle life of this carbon-metal composite can be long because the solid-electrolyte interface (SEI) on the carbon surface may protect both lithium and the metal particles in the carbon interior. In addition, the voids in the carbon interior may accommodate the nanoparticle's volume change, and such volume change may not cause much internal stress due to small sizes of the nanoparticles. This concept of improving carbon's performance to store and release lithium was demonstrated using experimental cells of C(Pd)/0.5M Lil-50/50 (vol.%) EC and DMC/Li, where C(Pd) was graphitized carbon fibers containing palladium nanoparticles, EC was ethylene carbonate, and DMC was dimethyl carbonate. However, such improvement was not observed if the Pd nanoparticles are replaced by aluminum, possibly because the aluminum nanoparticles were oxidized in air during storage, resulting in an inert oxide of aluminum. Further studies are needed to use this concept for practical applications.

  3. Charge transfer between sensing and targeted metal nanoparticles in indirect nanoplasmonic sensors

    NASA Astrophysics Data System (ADS)

    Zhdanov, Vladimir P.; Langhammer, Christoph

    2017-03-01

    In indirect nanoplasmonic sensors, the plasmonic metal nanoparticles are adjacent to the material of interest, and the material-related changes of their optical properties are used to probe that material. If the latter itself represents another metal in the form of nanoparticles, its deposition is accompanied by charge transfer to or from the plasmonic nanoparticles in order to equalize the Fermi levels. We estimate the value of the transferred charge and show on the two examples, nanoparticle sintering and hydride formation, that the charge transfer has negligible influence on the probed processes, because the effect of charge transfer is less important than that of nanoparticle surface energy. This further corroborates the non-invasive nature of nanoplasmonic sensors.

  4. A review on radiation-induced nucleation and growth of colloidal metallic nanoparticles

    PubMed Central

    2013-01-01

    This review presents an introduction to the synthesis of metallic nanoparticles by radiation-induced method, especially gamma irradiation. This method offers some benefits over the conventional methods because it provides fully reduced and highly pure nanoparticles free from by-products or chemical reducing agents, and is capable of controlling the particle size and structure. The nucleation and growth mechanism of metallic nanoparticles are also discussed. The competition between nucleation and growth process in the formation of nanoparticles can determine the size of nanoparticles which is influenced by certain parameters such as the choice of solvents and stabilizer, the precursor to stabilizer ratio, pH during synthesis, and absorbed dose. PMID:24225302

  5. Structural characterization of rotavirus-directed synthesis and assembly of metallic nanoparticle arrays.

    PubMed

    Plascencia-Villa, Germán; Medina, Ariosto; Palomares, Laura A; Ramírez, Octavio T; Ascencio, Jorge A

    2013-08-01

    Self-assembled structures derived of viral proteins display sophisticated structures that are difficult to obtain with even advanced synthesis methods and the use of protein nanotubes for synthesis and organization of inorganic nanoarrays into well-defined architectures are here reported. Nanoparticle arrays derived of rotavirus VP6 nanotubes were synthesized by in situ functionalization with silver and gold nanoparticles. The size and morphology of metal nanoparticles were characterized by transmission electron microscopy (TEM) and high resolution TEM (HR-TEM). Processing of micrographs to obtain fast Fourier transforms (FFT) patterns of nanoparticles shown that the preferred morphologies are fcc-like and multiple twinned ones. Micrographs were used to assign structure and orientation, and the elemental composition analysis was performed with energy dispersive spectroscopy (EDS). Structural characterization of functionalized rotavirus VP6 demonstrated its utility for directed construction of hybrid anisotropic nanomaterials formed by arrays of metallic nanoparticles.

  6. Mesoporous SnO2-coated metal nanoparticles with enhanced catalytic efficiency.

    PubMed

    Zhou, Na; Polavarapu, Lakshminarayana; Wang, Qing; Xu, Qing-Hua

    2015-03-04

    Aggregation of plasmonic nanoparticles under harsh conditions has been one of the major obstacles to their potential applications. Here we present the preparation of uniform mesoporous SnO2 shell coated Au nanospheres, Au nanorods and Au/Ag core-shell nanorods and their applications in molecular sensing and catalysis. In these nanostructures, the mesoporous SnO2 shell stabilizes the metal nanoparticle and allows the metal core to be exposed to the surrounding environment for various applications at the same time. These nanostructures display high refractive index sensitivity, which makes them promising materials for LSPR based molecular sensing. Applications of these materials as catalysts for reduction of 4-nitrophenol by NaBH4 have also been demonstrated. Both uncoated and SnO2-coated anisotropic Au and Au/Ag nanorods were found to display significantly better catalytic efficiency compared to the corresponding spherical Au nanoparticles. Catalytic activities of different metal nanoparticles were significantly enhanced by 4-6 times upon coating with the mesoporous SnO2 shell. The enhanced catalytic activity of metal nanoparticles upon SnO2 coating was attributed to charge-redistribution between noble metal and SnO2 that disperses the electrons to a large area and prolonged electron lifetime in SnO2-coated metal nanoparticles. The charge transfer mechanism of enhanced catalytic efficiency for SnO2-coated metal nanoparticles has been further demonstrated by photochemical reduction of silver ions on the outer surface of these NPs. These metal/semiconductor core-shell nanomaterials are potentially useful for various applications such as molecular sensing and catalysis.

  7. The Ability of Dental Specialists to Distinguish Lateral Incisor Metal-Free From Porcelain-Fused-to-Metal Implant Supported Crowns.

    PubMed

    De Melo, Eduardo V; Kauling, Ana Elisa C; Freitas, Sérgio Fernando T; Cardoso, Antônio C; Ferreira, Cimara Fortes

    2014-12-01

    The objective of this study was to evaluate the ability of dental specialists to distinguish lateral incisor metal-free from porcelain-fused-to-metal implant supported crowns in the anterior region. Five single-tooth implants in the maxillary lateral incisor region were restored with two types of implant-supported crowns (porcelain-fused-to-metal and metal-free). Photographs were presented to 20 evaluators. The evaluators had to answer whether the crown was: metal-free, porcelain-fused-to-metal or they could not tell the difference. The results showed that groups 1 (all participants), 3 (Restorative & Prosthodontic specialists), 4 (graduated 10 years) and 5 (graduated > 10 years) failed to respond correctly (P > 0.05) to which type of crown was presented to them. Group 2 (Periodontology & Implantology specialists) showed an accuracy rate of 35.6% (P = 0.009), in relation to metal-free crowns, 5.6 which is below the random index. The authors concluded that the evaluators from the 5 groups studied were unable to significantly distinguish which type of crown was used in the 10 presented situations.

  8. Metallic nanoparticles functionalizing carbon nanotube networks for gas sensing applications

    NASA Astrophysics Data System (ADS)

    Abdelhalim, Ahmed; Abdellah, Alaa; Scarpa, Giuseppe; Lugli, Paolo

    2014-02-01

    We report the fabrication of carbon nanotube (CNT) based gas sensors functionalized with different metallic nanoparticles (NPs) (Au, Pd, Ag) with exceptionally high responses towards four test gases (NH3, CO2, CO and ethanol). The CNT networks were fabricated through a low cost spray deposition process while the NPs were deposited by a thermal evaporation process. CNT based gas sensors functionalized with Au with a nominal thickness of 1.0 nm showed superior response towards NH3, CO and ethanol. The sensors’ normalized responses reached 92%, 22% and 32% with concentrations of 100 ppm, 50 ppm and 100 ppm for NH3, CO and ethanol respectively. CNT based gas sensors functionalized with Pd with a nominal thickness of 1.5 nm showed the best performance with CO2. The normalized response reached 3%, 6%, 12% and 17% with concentrations of 500 ppm, 1000 ppm, 2500 ppm and 5000 ppm of CO2 respectively. We also investigated the morphological and optical changes that occur to the NPs upon thermal treatment. Functionalization of CNT films deposited on glass with Au and Ag showed surface plasmon resonance effects that are dependent on the nominal thickness of the functionalization layer.

  9. Nanostructured target fabrication with metal and semiconductor nanoparticles

    NASA Astrophysics Data System (ADS)

    Barberio, M.; Antici, P.

    2015-10-01

    The development of ultra-intense high-energy (≫1 J) short (<1 ps) laser pulses in the last decade has enabled the acceleration of high-energy short-pulse proton beams. A key parameter for enhancing the acceleration regime is the laser-to-target absorption, which heavily depends on the target structure and material. In this work, we present the realization of a nanostructured target with a sub-laser wavelength nano-layer in the front surface as a possible candidate for improving the absorption. The nanostructured film was realized by a simpler and cheaper method than using conventional lithographic techniques: A colloidal solution of metallic or semiconductor nanoparticles (NPs) was produced by laser ablation and, after a heating and sonication process, was spray-dried on the front surface of an aluminum target. The obtained nanostructured film with a thickness of 1 μm appears, at morphological and chemical analysis, uniformly nanostructured and distributed on the target surface without the presence of oxides or external contaminants. Finally, the size of the NPs can be tuned from tens to hundreds of nanometers simply by varying the growth parameters (i.e., irradiation time, fluence, and laser beam energy).

  10. Metal-passivated PbS nanoparticles: fabrication and characterization.

    PubMed

    Tchaplyguine, M; Mikkelä, M-H; Mårsell, E; Polley, C; Mikkelsen, A; Zhang, W; Yartsev, A; Hetherington, C J D; Wallenberg, L R; Björneholm, O

    2017-03-08

    Organic-shell-free PbS nanoparticles have been produced in the size range relevant for quantum-dot solar cells (QDSCs) by a vapor aggregation method involving magnetron reactive sputtering. This method creates a beam of free 5-10 nm particles in a vacuum. The dimensions of the particles were estimated after their deposition on a substrate by imaging them using ex situ SEM and HRTEM electron microscopy. The particle structure and chemical composition could be deduced "on the fly", prior to deposition, using X-ray photoelectron spectroscopy (XPS) with tunable synchrotron radiation. Our XPS results suggest that under certain conditions it is possible to fabricate particles with a semiconductor core and 1 to 2 monolayer shells of metallic lead. For this case the absolute energy of the highest occupied molecular orbital (HOMO) in PbS has been determined to be (5.0 ± 0.5) eV below the vacuum level. For such particles deposited on a substrate HRTEM has confirmed the XPS-based conclusions on the crystalline PbS structure of the semiconductor core. Absorption spectroscopy on the deposited film has given a value of ∼1 eV for the lowest exciton. Together with the valence XPS results this has allowed us to reconstruct the energy level scheme of the particles. The results obtained are discussed in the context of the properties of PbS QDSCs.

  11. Electrochemical Characterization of Ultrathin Cross-Linked Metal Nanoparticle Films.

    PubMed

    Han, Chu; Percival, Stephen J; Zhang, Bo

    2016-09-06

    Here we report the preparation, characterization, and electrochemical study of conductive, ultrathin films of cross-linked metal nanoparticles (NPs). Nanoporous films ranging from 40 to 200 nm in thickness composed of gold and platinum NPs of ∼5 nm were fabricated via a powerful layer-by-layer spin coating process. This process allows preparation of uniform NP films as large as 2 × 2 cm(2) with precise control over thickness, structure, and electrochemical and electrocatalytic properties. Gold, platinum, and bimetallic NP films were fabricated and characterized using cyclic voltammetry, scanning electron microscopy, and conductance measurements. Their electrocatalytic activity toward the oxygen reduction reaction (ORR) was investigated. Our results show that the electrochemical activity of such NP films is initially hindered by the presence of dense thiolate cross-linking ligands. Both electrochemical cycling and oxygen plasma cleaning are effective means in restoring their electrochemical activity. Gold NP films have higher electric conductivity than platinum possibly due to more uniform film structure and closer particle-particle distance. The electrochemical and electrocatalytic performance of platinum NP films can be greatly enhanced by the incorporation of gold NPs. This work focuses on electrochemical characterization of cross-linked NP films and demonstrates several unique properties. These include quick and easy preparation, ultrathin and uniform film thickness, tunable structure and composition, and transferability to many other substrates.

  12. Quantum dynamical simulations of local field enhancement in metal nanoparticles.

    PubMed

    Negre, Christian F A; Perassi, Eduardo M; Coronado, Eduardo A; Sánchez, Cristián G

    2013-03-27

    Field enhancements (Γ) around small Ag nanoparticles (NPs) are calculated using a quantum dynamical simulation formalism and the results are compared with electrodynamic simulations using the discrete dipole approximation (DDA) in order to address the important issue of the intrinsic atomistic structure of NPs. Quite remarkably, in both quantum and classical approaches the highest values of Γ are located in the same regions around single NPs. However, by introducing a complete atomistic description of the metallic NPs in optical simulations, a different pattern of the Γ distribution is obtained. Knowing the correct pattern of the Γ distribution around NPs is crucial for understanding the spectroscopic features of molecules inside hot spots. The enhancement produced by surface plasmon coupling is studied by using both approaches in NP dimers for different inter-particle distances. The results show that the trend of the variation of Γ versus inter-particle distance is different for classical and quantum simulations. This difference is explained in terms of a charge transfer mechanism that cannot be obtained with classical electrodynamics. Finally, time dependent distribution of the enhancement factor is simulated by introducing a time dependent field perturbation into the Hamiltonian, allowing an assessment of the localized surface plasmon resonance quantum dynamics.

  13. Comparative Metal Oxide Nanoparticle Toxicity Using Embryonic Zebrafish

    PubMed Central

    Wehmas, Leah C.; Anders, Catherine; Chess, Jordan; Punnoose, Alex; Pereira, Cliff B.; Greenwood, Juliet A.; Tanguay, Robert L.

    2015-01-01

    Engineered metal oxide nanoparticles (MO NPs) are finding increasing utility in the medical field as anticancer agents. Before validation of in vivo anticancer efficacy can occur, a better understanding of whole-animal toxicity is required. We compared the toxicity of seven widely used semiconductor MO NPs made from zinc oxide (ZnO), titanium dioxide, cerium dioxide and tin dioxide prepared in pure water and in synthetic seawater using a five-day embryonic zebrafish assay. We hypothesized that the toxicity of these engineered MO NPs would depend on physicochemical properties. Significant agglomeration of MO NPs in aqueous solutions is common making it challenging to associate NP characteristics such as size and charge with toxicity. However, data from our agglomerated MO NPs suggests that the elemental composition and dissolution potential are major drivers of toxicity. Only ZnO caused significant adverse effects of all MO particles tested, and only when prepared in pure water (point estimate median lethal concentration = 3.5–9.1 mg/L). This toxicity was life stage dependent. The 24 h toxicity increased greatly (~22.7 fold) when zebrafish exposures started at the larval life stage compared to the 24 hour toxicity following embryonic exposure. Investigation into whether dissolution could account for ZnO toxicity revealed high levels of zinc ion (40–89% of total sample) were generated. Exposure to zinc ion equivalents revealed dissolved Zn2+ may be a major contributor to ZnO toxicity. PMID:26029632

  14. J-aggregates on metal nanoparticles characterized through ultrafast spectroscopy and near-field optics.

    PubMed

    Wiederrecht, Gary P; Wurtz, Gregory A; Im, Jin Seo; Hranisavljevic, Jasmina

    2004-01-01

    Illumination of metal nanoparticles at the plasmon resonance produces enhanced evanescent fields on the nanoparticles' surfaces. The unusual strength of the field makes it a target for exploring photoinduced phenomena at the nanoscale, if efficient functionalization or coating of the nanoparticle surface with appropriate chromophores is possible. One direction is to use cyanine dyes that form monolayers of J-aggregates on the surface of noble metal nanoparticle colloids. The unique, collective electronic properties of J-aggregates produce excitons with enormous extinction coefficients that are of interest for their efficient energy transfer, electron transfer, and nonlinear optical properties. In that vein, we report our results on time-resolved spectroscopy and near-field scanning optical microscopy (NSOM) of J-aggregate exciton dynamics on Ag and Au nanoparticle colloids. Ultrafast transient absorption studies show that J-aggregate exciton lifetimes on Ag nanoparticles are much longer than on Au nanoparticles, with a 300 ps lifetime that is two orders of magnitude longer than the electronic processes in the nanoparticles themselves. Complementary NSOM studies of the colloids show that fluorescence from the J-aggregates on the Ag nanoparticles is induced by the scanning probe. These results may be significant for improving the nanophotonic performance of hybrid materials for nanoscale applications.

  15. Bioactivity of noble metal nanoparticles decorated with biopolymers and their application in drug delivery.

    PubMed

    Rai, Mahendra; Ingle, Avinash P; Gupta, Indarchand; Brandelli, Adriano

    2015-12-30

    The unique properties of nanomaterials can be applied to solve different problems including new ways of drug delivery. Noble metal nanoparticles are most promising because they have been used for medicinal purposes since ancient time. It is evident from the past studies that the metallic nanoparticles are much more effective against various microorganisms when compared to their conventional counterparts. However, decoration of such nanoparticles with biomaterials add more advantages to their antimicrobial activity. Decoration of metal nanoparticles with biopolymers is a quite new area of research. Studies performed hitherto shown that nanoparticles of noble metals like silver, gold and platinum demonstrated better antibacterial, antifungal and antiviral activities when conjugated with biopolymers. The development of such technology has potential to develop materials that are more effective in the field of health science. Considering the importance and uniqueness of this concept, the present review aims to discuss the use of biopolymer-decorated metal nanoparticles for combating various diseases caused by microbial pathogens. Moreover, the nanotoxicity aspect has also been discussed.

  16. Comparisons of immersion and electrochemical properties of highly biocompatible Ti-15Zr-4Nb-4Ta alloy and other implantable metals for orthopedic implants

    NASA Astrophysics Data System (ADS)

    Okazaki, Yoshimitsu; Nagata, Hiroyuki

    2012-12-01

    Metal release from implantable metals and the properties of oxide films formed on alloy surfaces were analyzed, focusing on the highly biocompatible Ti-15Zr-4Nb-4Ta alloy. The thickness and electrical resistance (Rp) of the oxide film on such an alloy were compared with those of other implantable metals. The quantity of metal released during a 1-week immersion test was considerably smaller for the Ti-15Zr-4Nb-4Ta than the Ti-6Al-4V alloy. The potential (E10) indicating a current density of 10 μA cm-2 estimated from the anodic polarization curve was significantly higher for the Ti-15Zr-4Nb-4Ta than the Ti-6Al-4V alloy and other metals. Moreover, the oxide film (4-7 nm thickness) formed on the Ti-15Zr-4Nb-4Ta surface is electrochemically robust. The oxide film mainly consisted of TiO2 with small amounts of ZrO2, Nb2O5 and Ta2O5 that made the film electrochemically stable. The Rp of Ti-15Zr-4Nb-4Ta was higher than that of Ti-6Al-4V, i.e. 0.9 Ω cm2 in 0.9% NaCl and 1.3 Ω cm2 in Eagle's medium. This Rp was approximately five-fold higher than that of stainless steel, which has a history of more than 40 years of clinical use in the human body. Ti-15Zr-4Nb-4Ta is a potential implant material for long-term clinical use. Moreover, E10 and Rp were found to be useful parameters for assessing biological safety.

  17. Comparisons of immersion and electrochemical properties of highly biocompatible Ti–15Zr–4Nb–4Ta alloy and other implantable metals for orthopedic implants

    PubMed Central

    Okazaki, Yoshimitsu; Nagata, Hiroyuki

    2012-01-01

    Metal release from implantable metals and the properties of oxide films formed on alloy surfaces were analyzed, focusing on the highly biocompatible Ti–15Zr–4Nb–4Ta alloy. The thickness and electrical resistance (Rp) of the oxide film on such an alloy were compared with those of other implantable metals. The quantity of metal released during a 1-week immersion test was considerably smaller for the Ti–15Zr–4Nb–4Ta than the Ti–6Al–4V alloy. The potential (E10) indicating a current density of 10 μA cm−2 estimated from the anodic polarization curve was significantly higher for the Ti–15Zr–4Nb–4Ta than the Ti–6Al–4V alloy and other metals. Moreover, the oxide film (4–7 nm thickness) formed on the Ti–15Zr–4Nb–4Ta surface is electrochemically robust. The oxide film mainly consisted of TiO2 with small amounts of ZrO2, Nb2O5 and Ta2O5 that made the film electrochemically stable. The Rp of Ti–15Zr–4Nb–4Ta was higher than that of Ti–6Al–4V, i.e. 0.9 Ω cm2 in 0.9% NaCl and 1.3 Ω cm2 in Eagle's medium. This Rp was approximately five-fold higher than that of stainless steel, which has a history of more than 40 years of clinical use in the human body. Ti–15Zr–4Nb–4Ta is a potential implant material for long-term clinical use. Moreover, E10 and Rp were found to be useful parameters for assessing biological safety. PMID:27877543

  18. Design of radio frequency pulse waveforms for mitigating signal inhomogeneity in magnetic resonance imaging due to metallic implants

    NASA Astrophysics Data System (ADS)

    Woo, Taeseong; Kim, Dongmin; Someya, Takao; Sekino, Masaki

    2015-05-01

    Metallic implants can result in considerable inhomogeneity in the signal intensity of magnetic resonance imaging (MRI), because the implant generates a shielding effect to the applied radio-frequency (RF) magnetic fields. In this study, we propose an acquisition method to mitigate the signal inhomogeneities using an adaptive RF pulse waveform. The effectiveness of the method was investigated using both numerical simulations and experiments. The RF pulse waveform was calculated based on inverse analyses of the Bloch equation incorporating the measured RF field distribution within the object. A simulation was carried out using a simplified numerical model of RF field inhomogeneity assumed at the center of model. An RF pulse waveform was designed to recover the attenuated signal region in the given model, and we show a significant improvement in the signal homogeneity compared with that obtained using a conventional pulse. We implemented the proposed method on a 7T-MRI system to show the efficacy experimentally. Test samples were fabricated from agarose gel with inserted copper or aluminum implants of different thicknesses. The RF pulse for selective excitation was calculated after mapping the RF field distribution of each imaging object. The acquired images exhibit an improvement in the homogeneity at the region of metallic implants. These results indicate that the proposed method is effective for MRI measurements of objects containing metallic implants.

  19. Laser and electron-beam powder-bed additive manufacturing of metallic implants: A review on processes, materials and designs.

    PubMed

    Sing, Swee Leong; An, Jia; Yeong, Wai Yee; Wiria, Florencia Edith

    2016-03-01

    Additive manufacturing (AM), also commonly known as 3D printing, allows the direct fabrication of functional parts with complex shapes from digital models. In this review, the current progress of two AM processes suitable for metallic orthopaedic implant applications, namely selective laser melting (SLM) and electron beam melting (EBM) are presented. Several critical design factors such as the need for data acquisition for patient-specific design, design dependent porosity for osteo-inductive implants, surface topology of the implants and design for reduction of stress-shielding in implants are discussed. Additive manufactured biomaterials such as 316L stainless steel, titanium-6aluminium-4vanadium (Ti6Al4V) and cobalt-chromium (CoCr) are highlighted. Limitations and future potential of such technologies are also explored.

  20. Influence of the clearance on in-vitro tribology of large diameter metal-on-metal articulations pertaining to resurfacing hip implants.

    PubMed

    Rieker, Claude B; Schön, Rolf; Konrad, Reto; Liebentritt, Gernot; Gnepf, Patric; Shen, Ming; Roberts, Paul; Grigoris, Peter

    2005-04-01

    Large-diameter metal-on-metal articulations may provide an opportunity for wear reduction in total hip implants because earlier studies have shown that the formation of a fluid film that completely separates the bearing surfaces is theoretically possible. In such a lubrication mode and under ideal conditions, there is theoretically no amount of wear. Studies have suggested that the two primary parameters controlling the lubrication mode are the diameter and the clearance of the articulation. The goal of the present study was to experimentally investigate the influence of these two parameters on the wear behavior of large-diameter metal-on-metal articulations pertaining to resurfacing hip implants. The results of this in vitro investigation showed that longer running-in periods and higher amounts of running-in wear were associated with larger clearances.

  1. Surface damage of metallic implants due to mechanical loading and chemical reactions

    NASA Astrophysics Data System (ADS)

    Ryu, Jaejoong

    The present study investigates interfacial damage mechanism of modular implants due to synergetic action of mechanical contact loading and corrosion. Modular implants are manufactured such that surfaces have a characteristic degree of roughness determined by tool tip size and motion of tool path or feeding speed. The central hypothesis for this work is that during contact loading of metallic implants, mechanisms of damage and dissolution are determined by contact loads, plastic deformation, residual stresses and environmental conditions at the nanoscale surface asperities; while during subsequent rest periods, mechanism of metallic dissolution is determined by the environmental conditions and residual stress field induced due to long range elastic interactions of the plastically deformed asperities. First part of the thesis is focused on investigating the mechanisms underlying surface roughness evolution due to stress-assisted dissolution during the rest period. The latter part is focused on investigating material removal mechanisms during single asperity contact of implant surfaces. Experimental study was performed to elucidate the roughness evolution mechanism by combined effect of multi-asperity contact and environmental corrosion. Cobalt-chromium-molybdenum specimen was subjected to either contact loading alone or alternating contact loading and exposure to reactive environment. Roughness of the specimen surface was monitored by optical profilometry and Fast Fourier Transform (FFT) calculation was used to characterize the evolving behavior of roughness modes. Finite element analysis (FEA) was employed to identify influences of surface morphological configurations and contact pressures on the residual stress development. Analytical model of multi-asperity contact has been developed for prediction of residual stress field for different roughness configurations during varying magnitude of contact loads based on elastic inclusion theory. Experimental results

  2. Supersaturating silicon with transition metals by ion implantation and pulsed laser melting

    SciTech Connect

    Recht, Daniel; Aziz, Michael J.; Smith, Matthew J.; Gradečak, Silvija; Charnvanichborikarn, Supakit; Williams, James S.; Sullivan, Joseph T.; Winkler, Mark T.; Buonassisi, Tonio; Mathews, Jay; Warrender, Jeffrey M.

    2013-09-28

    We investigate the possibility of creating an intermediate band semiconductor by supersaturating Si with a range of transition metals (Au, Co, Cr, Cu, Fe, Pd, Pt, W, and Zn) using ion implantation followed by pulsed laser melting (PLM). Structural characterization shows evidence of either surface segregation or cellular breakdown in all transition metals investigated, preventing the formation of high supersaturations. However, concentration-depth profiling reveals that regions of Si supersaturated with Au and Zn are formed below the regions of cellular breakdown. Fits to the concentration-depth profile are used to estimate the diffusive speeds, v{sub D,} of Au and Zn, and put lower bounds on v{sub D} of the other metals ranging from 10{sup 2} to 10{sup 4} m/s. Knowledge of v{sub D} is used to tailor the irradiation conditions and synthesize single-crystal Si supersaturated with 10{sup 19} Au/cm{sup 3} without cellular breakdown. Values of v{sub D} are compared to those for other elements in Si. Two independent thermophysical properties, the solute diffusivity at the melting temperature, D{sub s}(T{sub m}), and the equilibrium partition coefficient, k{sub e}, are shown to simultaneously affect v{sub D}. We demonstrate a correlation between v{sub D} and the ratio D{sub s}(T{sub m})/k{sub e}{sup 0.67}, which is exhibited for Group III, IV, and V solutes but not for the transition metals investigated. Nevertheless, comparison with experimental results suggests that D{sub s}(T{sub m})/k{sub e}{sup 0.67} might serve as a metric for evaluating the potential to supersaturate Si with transition metals by PLM.

  3. Supersaturating silicon with transition metals by ion implantation and pulsed laser melting

    NASA Astrophysics Data System (ADS)

    Recht, Daniel; Smith, Matthew J.; Charnvanichborikarn, Supakit; Sullivan, Joseph T.; Winkler, Mark T.; Mathews, Jay; Warrender, Jeffrey M.; Buonassisi, Tonio; Williams, James S.; Gradečak, Silvija; Aziz, Michael J.

    2013-09-01

    We investigate the possibility of creating an intermediate band semiconductor by supersaturating Si with a range of transition metals (Au, Co, Cr, Cu, Fe, Pd, Pt, W, and Zn) using ion implantation followed by pulsed laser melting (PLM). Structural characterization shows evidence of either surface segregation or cellular breakdown in all transition metals investigated, preventing the formation of high supersaturations. However, concentration-depth profiling reveals that regions of Si supersaturated with Au and Zn are formed below the regions of cellular breakdown. Fits to the concentration-depth profile are used to estimate the diffusive speeds, vD, of Au and Zn, and put lower bounds on vD of the other metals ranging from 102 to 104 m/s. Knowledge of vD is used to tailor the irradiation conditions and synthesize single-crystal Si supersaturated with 1019 Au/cm3 without cellular breakdown. Values of vD are compared to those for other elements in Si. Two independent thermophysical properties, the solute diffusivity at the melting temperature, Ds(Tm), and the equilibrium partition coefficient, ke, are shown to simultaneously affect vD. We demonstrate a correlation between vD and the ratio Ds(Tm)/ke0.67, which is exhibited for Group III, IV, and V solutes but not for the transition metals investigated. Nevertheless, comparison with experimental results suggests that Ds(Tm)/ke0.67 might serve as a metric for evaluating the potential to supersaturate Si with transition metals by PLM.

  4. SINGLE-PARTICLE ICPMS FOR CHARACTERIZING METAL-BASED NANOPARTICLES IN THE ENVIRONMENT - ADVANCES AND CHALLENGES

    EPA Science Inventory

    As engineered metal-based nanomaterials become widely used in consumer and industrial products, the amount of these materials introduced into the environment by a variety of paths will increase. The concentration of metal associated with these engineered nanoparticles will be s...

  5. A SAXS study of the impregnation of pH-responsive polymeric microgels with metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Anastasiadis, S. H.; Pavlopoulou, E.; Vamvakaki, M.; Christodoulakis, K. E.; Portale, G.; Bras, W.

    2010-03-01

    We follow the synthesis of metal nanoparticles within poly(2- (diethylamino)ethyl methacrylate), PDEA, microgels by SAXS. Colloidal Pt nanocrystals are formed within the microgels by the incorporation of the appropriate metal precursor, i.e., H2PtCl6, followed by metal reduction. We report the structural study of these systems by SAXS during the three steps of the metal nanoparticle synthesis: the original dispersions in water, the metal-loaded polymer matrices and the metal-nanoparticle-containing microgels after reduction. The scattering profiles of the pure microgel dispersions exhibit two contributions; a Porod-like wavevector q contribution arising from the water/microgel interface and a power law fractal contribution due to the microgel network. Both the Porod and the power-law scattering are still evident after metal incorporation, while the shoulder appearing at higher q's can be attributed to the formation of domains of higher scattering intensity due to the aggregation of the ion- neutralized hydrophobic polymer within the microgels. After metal reduction, Pt nanoparticles are formed with sizes of around 1.5 nm in diameter. Sponsored by NATO's Scientific Affairs Division, by the Greek GSRT and by the EU.

  6. Floating AC-DEP (dielectrophoretic) manipulations of fluorescent nanoparticle at metal nanostructure for plasmonic applications

    NASA Astrophysics Data System (ADS)

    Kim, J.; Shin, H. J.; Hwang, K. S.; Park, J. H.

    2014-11-01

    We propose the fluorescent nanoparticle manipulations at nano-metal structures with floating AC-DEP force for plasmonic applications. The electrode gap was optimized to induce enough DEP force around the nano-structure for manipulation of the nanoparticles. 10um wide gap of electrode was acquired to apply the floating AC-DEP force at various designed metal nano-structure such as nanowire, y-branch and vortex. The all shape of nano-metal structures are formed at the gap of microelectrode and not connected with microelectrode. The gold nano-structures in the gap of microelectrode were fabricated with e-beam lithography and lift-off process. Before the formation of metal nanostructure, micro electrodes for applying the electric field around the metal nano-structures were fabricated with photolithography and lift-off process. Cadmium selenide (CdSe/ZnS) QDs (0.8 nM, emission wavelength of 605 nm) with a 25 nm zinc sulfide capping layer and 100nm polystyrene nano bead (1 nM, emission wavelength of 610nm) were used as fluorescent nanoparticles. We applied the 8 Vpp, 3 MHz sine wave for the positive DEP force, and it resulted in 108 V/m electric field and 1011 V/m electric field gradient around gold nanowire with floating AC. The fluorescent nanoparticle's attachment at the nanowire is confirmed by the fluorescent optical analysis. The fluorescent nanoparticles are located successfully at designed metal nano-structures for plasmonic applications.

  7. Microstructural disintegration in dense hydroxyapatite and hydroxyapatite-coated metal implants

    NASA Astrophysics Data System (ADS)

    Seo, Dong Seok; Lee, Jong Kook

    2007-08-01

    Hydroxyapatite (HA) has been widely used as a coating for orthopedic metal implants. An important concern regarding HA coating is its degradation of the biological milieu. In this study, the microstructure of a retrieved HA-coated acetabular cup implanted for four years after total hip arthroplasty (THA) was investigated by field emission scanning electron microscopy. In order to understand the underlying mechanism, of degradation and exfoliation of the HA coating, degradation of phase-pure and dense HA ceramics was also observed by in vitro and in vivo testing. The surface morphology and fracture surfaces of HA ceramics revealed that the dissolution starting at the surface extended inwards resulting in particle loosening and microstructural-level degradation. The dissolution features of HA ceramics were similar to the case of HA coating. It was found that extensive dissolution of the coating occurred and most of the coating disappeared. The majority of the remaining graints were fractured by the intergranular mode, suggesting that grain boundaries should be predominantly dissolved. These observations may explain the mechanism through which the biological stability of the HA coated layer becomes unexpectedly poor.

  8. Management of Biliary Neoplastic Obstruction with Two Different Metallic Stents Implanted in One Session

    SciTech Connect

    Gandini, Roberto; Fabiano, S. Pipitone, Vincenzo; Spinelli, Alessio; Reale, Carlo Andrea; Colangelo, Vittorio; Pampana, Enrico; Romagnoli, Andrea; Simonetti, Giovanni

    2005-01-15

    The efficacy of the 'one-step' technique using two different metallic stents (Wallstent and Ultraflex) and associated rate of complications was studied in 87 patients with jaundice secondary to malignant biliary obstruction, with bilirubin level less than 15 mg/dl and Bismuth type 1 or 2 strictures. The study group, composed of 40 men and 47 women with a mean age of 59.4 years (range 37-81 years), was treated with a 'one-step' percutaneous transhepatic implantation of self-expanding stents. The cause of the obstruction was pancreatic carcinoma in 38 patients (44%), lymph node metastasis in 20 patients (23%), gallbladder carcinoma in 13 patients (15%), cholangiocarcinoma in 12 patients (14%) and ampullary carcinoma in four patients (5%). A significant reduction in jaundice was obtained in all but one patient, with a drop of total serum bilirubin level from a mean of 13.7 mg/dl to 4.3 mg/dl within the first 4 days. The mean postprocedural hospitalization period was 5.4 days in the Wallstent group and 6.4 days in the Ultraflex group. Mean survival rate was 7.8 months (Wallstent group) and 7.1 months (Ultraflex group). The use of both stents did not reveal any significant difference in parameters tested. The implantation of these self-expandable stents in one session, in selected patients, is clinically effective, devoid of important complications and cost-effective due to the reduction in hospitalization.

  9. Tissue reaction to implants of different metals: a study using guide wires in cannulated screws.

    PubMed

    Devine, D M; Leitner, M; Perren, S M; Boure, L P; Pearce, S G

    2009-10-20

    Cannulated screws, along with guide wires, are typically used for surgical fracture treatment in cancellous bone. Breakage or bending deformation of the guide wire is a clinical concern. Mechanically superior guide wires made of Co-Cr alloys such as MP35N and L605 may reduce the occurrence of mechanical failures when used in combination with conventional (316L stainless steel) cannulated screws. However the possibility of galvanic or crevice corrosion and adverse tissue reaction, exists when using dissimilar materials, particularly in the event that a guide wire breaks, and remains in situ. Therefore, we designed an experiment to determine the tissue reaction to such an in vivo environment. Implant devices were designed to replicate a clinical situation where dissimilar metals can form a galvanic couple. Histological and SEM analyses were used to evaluate tissue response and corrosion of the implants. In this experiment, no adverse in vivo effects were detected from the use of dissimilar materials in a model of a broken guide wire in a cannulated screw.

  10. An exploration of plastic deformation dependence of cell viability and adhesion in metallic implant materials.

    PubMed

    Uzer, B; Toker, S M; Cingoz, A; Bagci-Onder, T; Gerstein, G; Maier, H J; Canadinc, D

    2016-07-01

    The relationship between cell viability and adhesion behavior, and micro-deformation mechanisms was investigated on austenitic 316L stainless steel samples, which were subjected to different amounts of plastic strains (5%, 15%, 25%, 35% and 60%) to promote a variety in the slip and twin activities in the microstructure. Confocal laser scanning microscopy (CLSM) and field emission scanning electron microscopy (FESEM) revealed that cells most favored the samples with the largest plastic deformation, such that they spread more and formed significant filopodial extensions. Specifically, brain tumor cells seeded on the 35% deformed samples exhibited the best adhesion performance, where a significant slip activity was prevalent, accompanied by considerable slip-twin interactions. Furthermore, maximum viability was exhibited by the cells seeded on the 60% deformed samples, which were particularly designed in a specific geometry that could endure greater strain values. Overall, the current findings open a new venue for the production of metallic implants with enhanced biocompatibility, such that the adhesion and viability of the cells surrounding an implant can be optimized by tailoring the surface relief of the material, which is dictated by the micro-deformation mechanism activities facilitated by plastic deformation imposed by machining.

  11. A Genetically Modified Tobacco Mosaic Virus that can Produce Gold Nanoparticles from a Metal Salt Precursor

    PubMed Central

    Love, Andrew J.; Makarov, Valentine V.; Sinitsyna, Olga V.; Shaw, Jane; Yaminsky, Igor V.; Kalinina, Natalia O.; Taliansky, Michael E.

    2015-01-01

    We genetically modified tobacco mosaic virus (TMV) to surface display a characterized peptide with potent metal ion binding and reducing capacity (MBP TMV), and demonstrate that unlike wild type TMV, this construct can lead to the formation of discrete 10–40 nm gold nanoparticles when mixed with 3 mM potassium tetrachloroaurate. Using a variety of analytical physicochemical approaches it was found that these nanoparticles were crystalline in nature and stable. Given that the MBP TMV can produce metal nanomaterials in the absence of chemical reductants, it may have utility in the green production of metal nanomaterials. PMID:26617624

  12. Enhanced absorption with quantum dots, metal nanoparticles, and 2D materials

    NASA Astrophysics Data System (ADS)

    Simsek, Ergun; Mukherjee, Bablu; Guchhait, Asim; Chan, Yin Thai

    2016-03-01

    We fabricate and characterize mono- and few- layers of MoS2 and WSe2 on glass and SiO2/Si substrates. PbS quantum dots and/or Au nanoparticles are deposited on the fabricated thin metal dichalcogenide films by controlled drop casting and electron beam evaporation techniques. The reflection spectra of the fabricated structures are measured with a spatially resolved reflectometry setup. Both experimental and numerical results show that surface functionalization with metal nanoparticles can enhance atomically thin transition metal dichalcogenides' absorption and scattering capabilities, however semiconducting quantum dots do not create such effect.

  13. Metal gettering by boron-silicide precipitates in boron-implanted silicon

    SciTech Connect

    Myers, S.M.; Petersen, G.A.; Headley, T.J.; Michael, J.R.; Aselage, T.A.; Seager, C.H.

    1996-09-01

    We show that Fe, Co, Cu, and Au impurities in Si are strongly gettered to boron-silicide precipitates formed by supersaturation B implantation and annealing. Effective binding free energies relative to interstitial solution range form somewhat above 1 to more than 2 eV. The B-Si precipitates formed at temperatures {le}1100{degrees}C lack long range structural order but closely resemble and icosahedral B{sub 3}Si phase in composition, local bonding, and chemical potential. Evidence indicates that the metal atoms go into solution in the B-Si phase, and this is interpreted in terms of the novel bonding and structural characteristics of B-rich icosahedral compounds.

  14. Heat and mass transfer enhancement of nanofluids flow in the presence of metallic/metallic-oxides spherical nanoparticles

    NASA Astrophysics Data System (ADS)

    Qureshi, M. Zubair Akbar; Ali, Kashif; Iqbal, M. Farooq; Ashraf, Muhammad; Ahmad, Shazad

    2017-01-01

    The numerical study of heat and mass transfer for an incompressible magnetohydrodynamics (MHD) nanofluid flow containing spherical shaped nanoparticles through a channel with moving porous walls is presented. Further, another endeavour is to study the effect of two types of fluids, namely the metallic nanofluid (Au + water) and metallic-oxides nanofluid (TiO2 + water) are studied. The phenomena of spherical metallic and metallic-oxides nanoparticles have been also mathematically modelled by using the Hamilton-Crosser model. The influence of the governing parameters on the flow, heat and mass transfer aspects of the problem is discussed. The outcome of the investigation may be beneficial to the application of biotechnology and industrial purposes. Numerical solutions for the velocity, heat and mass transfer rate at the boundary are obtained and analysed.

  15. Tissue Restoration After Implantation of Polyglycolide, Polydioxanone, Polylevolactide, and Metallic Pins in Cortical Bone: An Experimental Study in Rabbits

    PubMed Central

    Salminen, Sari T.; Tynninen, Olli; Böstman, Ole M.; Laitinen, Outi

    2010-01-01

    We performed qualitative and histoquantitative investigations of tissue restoration after implanting polyglycolide (PGA), polydioxanone (PDS), polylevolactide (PLLA), and stainless steel pins in the intramedullary canal of rabbit femurs. The effect of bioabsorbable devices on healing of a cortical bone defect was also assessed. The cortical bone defect was created in the right femur of 80 rabbits. Bioabsorbable and metallic pins in 60 and two metallic pins alone were implanted in 20 intramedullary canals; 80 left femurs served as intact controls. Follow-up times were 3, 6, 12, 24, and 52 weeks. At all time points, collagenous connective tissue, including bone trabeculae, surrounded the implant at the tissue–implant interface, replacing hematopoiesis and fat of the intramedullary canal. The groups did not differ in the area and trabecular bone area fraction of the resulting callus. Residual fragments of PGA and PDS were observed at 24 weeks, and complete degradation occurred within 52 weeks. PGA, PDS, PLLA, and metallic implants induced a bony and fibrous walling-off response in the intramedullary cavity. No inflammation was observed. Complete tissue restoration did not occur within the follow-up, even after complete degradation of PGA and PDS, which had shorter degradation times than PLLA. The cortical bone healing effect was not different between bioabsorbable pins and metallic wires. Thus, these polymers had no specific osteostimulatory or osteoinhibitory properties compared to stainless steel. Within the follow-up period, there were no significant differences in biocompatibility between the implants and no adverse inflammatory foreign-body reactions. PMID:20495791

  16. Metal oxide nanoparticle transport in porous media - an analysis about (un)certainties in environmental research

    NASA Astrophysics Data System (ADS)

    Heidmann, I.

    2013-04-01

    Research about the fate and behavior of engineered nanoparticles in the environment is despite its wide applications still in the early stages. The fast-growing area of nanoparticle research and the high level of uncertainty create a big challenge for describing clearly the recent state of the current scientific knowledge. Therefore, in this study the certain knowledge, the known uncertainties and the identified knowledge gaps concerning mobility of engineered metal oxide nanoparticles in porous media are analyzed. The mobility of nanoparticles is mainly investigated in model laboratory studies under well-defined conditions, which are often not realistic for natural systems. In these model systems, nanoparticles often retain in the pore system due to aggregation and sedimentation. However, under environmental conditions, the presence of natural organic matter may cause stabilization or disaggregation of nanoparticles and favors therefore higher mobility of nanoparticles. Additionally, potential higher mobility of particles using preferential flow paths is not considered. Knowledge of the long-term behavior of nanoparticles concerning disaggregation, dissolution or remobilization in soils under environmental conditions is scarce. Scientific uncertainty itself is rarely mentioned in the research papers. Seldom known methodically uncertainties in nanoparticle characterization are referred to. The uncertainty about the transferability of the results to environmental conditions is discussed more often. Due to the sparse studies concerning natural material or natural pore systems, certain conclusions concerning the mobility of nanoparticles in the soil environment are not possible to drawn.

  17. Assessing nanoparticle size effects on metal hydride thermodynamics using the Wulff construction.

    PubMed

    Kim, Ki Chul; Dai, Bing; Karl Johnson, J; Sholl, David S

    2009-05-20

    The reaction thermodynamics of metal hydrides are crucial to the use of these materials for reversible hydrogen storage. In addition to altering the kinetics of metal hydride reactions, the use of nanoparticles can also change the overall reaction thermodynamics. We use density functional theory to predict the equilibrium crystal shapes of seven metals and their hydrides via the Wulff construction. These calculations allow the impact of nanoparticle size on the thermodynamics of hydrogen release from these metal hydrides to be predicted. Specifically, we study the temperature required for the hydride to generate a H(2) pressure of 1 bar as a function of the radius of the nanoparticle. In most, but not all, cases the hydrogen release temperature increases slightly as the particle size is reduced.

  18. Super adsorption capability from amorphousization of metal oxide nanoparticles for dye removal

    PubMed Central

    Li, L. H.; Xiao, J.; Liu, P.; Yang, G. W.

    2015-01-01

    Transitional metal oxide nanoparticles as advanced environment and energy materials require very well absorption performance to apply in practice. Although most metal oxides are based on crystalline, high activities can also be achieved with amorphous phases. Here, we reported the adsorption behavior and mechanism of methyl blue (MB) on the amorphous transitional metal oxide (Fe, Co and Ni oxides) nanoparticles, and we demonstrated that the amorphousization of transitional metal oxide (Fe, Co and Ni oxides) nanoparticles driven by a novel process involving laser irradiation in liquid can create a super adsorption capability for MB, and the maximum adsorption capacity of the fabricated NiO amorphous nanostructure reaches up to 10584.6 mgg−1, the largest value reported to date for all MB adsorbents. The proof-of-principle investigation of NiO amorphous nanophase demonstrated the broad applicability of this methodology for obtaining new super dyes adsorbents. PMID:25761448

  19. Laser heating of metallic nanoparticles for photothermal ablation applications

    NASA Astrophysics Data System (ADS)

    Liu, Xiaoming; Shan, Guangshuai; Yu, Junsheng; Yang, Wei; Ren, Zhaodi; Wang, Xiaohui; Xie, Xi; Chen, Hui-jiuan; Chen, Xiaodong

    2017-02-01

    In order to search for a suitable frequency and material with higher photothermal efficacy for hyperthermia application in cancer treatment, a comparative study on laser heating of Au/Ag nanoparticles and Ag nanowires has been conducted. It is found that gold nanoparticles are more photothermal efficient in comparison with silver nanoparticles and silver nanowires at 450nm and 532 nm. Gold nanoparticles are more heated by 532 nm laser than 450 nm laser. In contrast, silver nanoparticles show slightly less temperature rise at 532 nm than 450 nm laser. For silver nanowires, no significant photothermal effect has been observed. Size-dependent effect study indicates that the absorption efficiency of single gold nanoparticles of larger diameter is higher than that of smaller diameter, in the diameter range of 0-50nm. A mathematical model for describing the heating profile in the heating sample has been built. The mathematical model can be utilized to predict the optimal treatment size of tumor.

  20. Extraction of chlorpyrifos and malathion from water by metal nanoparticles.

    PubMed

    Nair, A Sreekumaran; Pradeep, T

    2007-06-01

    The nanoparticles of gold and silver in solution state and supported over activated alumina are effective systems for the quantitative removal of chlorpyrifos and malathion, two common pesticides found in surface waters of developing nations, from water. In the solution phase, these pesticides adsorb onto the nanoparticles' surfaces and upon interaction for a long time, the nanoparticles with adsorbed pesticides precipitate. In contrast, complete removal of these pesticides occurs when contaminated water is passed over nanoparticles supported on alumina. A prototype of an on-line filter was made using a column of activated alumina powder loaded with silver nanoparticles and the device was used for pesticide removal for extended periods. We believe that the method has great technological potential in drinking water purification, especially using silver nanoparticles.

  1. Peculiarities of metal oxide nanoparticles obtained in acoustoplasma discharge

    NASA Astrophysics Data System (ADS)

    Bulychev, N. A.; Kazaryan, M. A.; Nikiforov, V. N.; Shevchenko, S. N.; Yakunin, V. G.; Timoshenko, V. Yu.; Bychenko, A. B.; Sredin, V. G.

    2016-05-01

    Nanoparticles of tungsten, copper, iron, and zinc oxides were synthesized in acoustoplasma discharge. Their size distribution was studied by electron microscopy and laser correlation spectroscopy. Ultrasound was found to narrow significantly the size distribution width of zinc oxide nanoparticles. Water suspensions of zinc oxide nanoparticles showed photoluminescence in red and near infrared spectral ranges, which makes them a promising material for luminescent diagnostics of biological systems.

  2. An electrodynamics-Langevin dynamics (ED-LD) approach to simulate metal nanoparticle interactions and motion.

    PubMed

    Sule, N; Rice, S A; Gray, S K; Scherer, N F

    2015-11-16

    Understanding the formation of electrodynamically interacting assemblies of metal nanoparticles requires accurate computational methods for determining the forces and propagating trajectories. However, since computation of electromagnetic forces occurs on attosecond to femtosecond timescales, simulating the motion of colloidal nanoparticles on milliseconds to seconds timescales is a challenging multi-scale computational problem. Here, we present a computational technique for performing accurate simulations of laser-illuminated metal nanoparticles. In the simulation, we self-consistently combine the finite-difference time-domain method for electrodynamics (ED) with Langevin dynamics (LD) for the particle motions. We demonstrate the ED-LD method by calculating the 3D trajectories of a single 100-nm-diameter Ag nanoparticle and optical trapping and optical binding of two and three 150-nm-diameter Ag nanoparticles in simulated optical tweezers. We show that surface charge on the colloidal metal nanoparticles plays an important role in their optically driven self-organization. In fact, these simulations provide a more complete understanding of the assembly of different structures of two and three Ag nanoparticles that have been observed experimentally, demonstrating that the ED-LD method will be a very useful tool for understanding the self-organization of optical matter.

  3. Potential application of metal nanoparticles for dosimetric systems: Concepts and perspectives

    NASA Astrophysics Data System (ADS)

    Guidelli, Eder José; Baffa, Oswaldo

    2014-11-01

    Metallic nanoparticles increase the delivered dose and consequently enhance tissue radio sensitization during radiation therapy of cancer. The Dose Enhancement Factor (DEF) corresponds to the ratio between the dose deposited on a tissue containing nanoparticles, and the dose deposited on a tissue without nanoparticles. In this sense, we have used electron spin resonance spectroscopy (ESR) to investigate how silver and gold nanoparticles affect the dose deposition in alanine dosimeters, which act as a surrogate of soft tissue. Besides optimizing radiation absorption by the dosimeter, the optical properties of these metal nanoparticles could also improve light emission from materials employed as radiation detectors. Therefore, we have also examined how the plasmonic properties of noble metal nanoparticles could enhance radiation detection using optically stimulated luminescence (OSL) dosimetry. This work will show results on how the use of gold and silver nanoparticles are beneficial for the ESR and OSL dosimetric techniques, and will describe the difficulties we have been facing, the challenges to overcome, and the perspectives.

  4. Potential application of metal nanoparticles for dosimetric systems: Concepts and perspectives

    SciTech Connect

    Guidelli, Eder José Baffa, Oswaldo

    2014-11-07

    Metallic nanoparticles increase the delivered dose and consequently enhance tissue radio sensitization during radiation therapy of cancer. The Dose Enhancement Factor (DEF) corresponds to the ratio between the dose deposited on a tissue containing nanoparticles, and the dose deposited on a tissue without nanoparticles. In this sense, we have used electron spin resonance spectroscopy (ESR) to investigate how silver and gold nanoparticles affect the dose deposition in alanine dosimeters, which act as a surrogate of soft tissue. Besides optimizing radiation absorption by the dosimeter, the optical properties of these metal nanoparticles could also improve light emission from materials employed as radiation detectors. Therefore, we have also examined how the plasmonic properties of noble metal nanoparticles could enhance radiation detection using optically stimulated luminescence (OSL) dosimetry. This work will show results on how the use of gold and silver nanoparticles are beneficial for the ESR and OSL dosimetric techniques, and will describe the difficulties we have been facing, the challenges to overcome, and the perspectives.

  5. Catalytic and photocatalytic transformations on metal nanoparticles with targeted geometric and plasmonic properties.

    PubMed

    Linic, Suljo; Christopher, Phillip; Xin, Hongliang; Marimuthu, Andiappan

    2013-08-20

    Heterogeneous catalysis by metals was among the first enabling technologies that extensively relied on nanoscience. The early intersections of catalysis and nanoscience focused on the synthesis of catalytic materials with high surface to volume ratio. These synthesis strategies mainly involved the impregnation of metal salts on high surface area supports. This would usually yield quasi-spherical nanoparticles capped by low-energy surface facets, typically with closely packed metal atoms. These high density areas often function as the catalytically active surface sites. Unfortunately, strategies to control the functioning surface facet (i.e., the geometry of active sites that performs catalytic turnover) are rare and represent a significant challenge in our ability to fine-tune and optimize the reactive surfaces. Through recent developments in colloidal chemistry, chemists have been able to synthesize metallic nanoparticles of both targeted size and desired shape. This has opened new possibilities for the design of heterogeneous catalytic materials, since metal nanoparticles of different shapes are terminated with different surface facets. By controlling the surface facet exposed to reactants, we can start affecting the chemical transformations taking place on the metal particles and changing the outcome of catalytic processes. Controlling the size and shape of metal nanoparticles also allows us to control the optical properties of these materials. For example, noble metals nanoparticles (Au, Ag, Cu) interact with UV-vis light through an excitation of localized surface plasmon resonance (LSPR), which is highly sensitive to the size and shape of the nanostructures. This excitation is accompanied by the creation of short-lived energetic electrons on the surface of the nanostructure. We showed recently that these energetic electrons could drive photocatalytic transformations on these nanostructures. The photocatalytic, electron-driven processes on metal nanoparticles

  6. Laser-ablation-induced synthesis of SiO2-capped noble metal nanoparticles in a single step.

    PubMed

    Jiménez, Ernesto; Abderrafi, Kamal; Abargues, Rafael; Valdés, José L; Martínez-Pastor, Juan P

    2010-05-18

    Here we describe a simple, powerful technique based on the laser ablation of a target immersed in a water solution of a metal salt. With this method, nanoparticles of different metals and alloys can be processed very quickly. Both the target and the salt solution can be chosen to produce metal nanoparticles of different sizes, surface-oxidized nanoparticles (silica-silver, for example), or even more complex structures to be defined by the researcher on one or more steps because the technique combines the advantages of both physical and chemical methods. We have applied this technique to the fabrication of inert silica-metal (silver, gold, and silver-gold) nanoparticles with a strong surface plasmon resonance all together in a single step. The advantage of the simultaneous production of silica during laser ablation is the stabilization of the metal nanoparticle colloid but also the possibility to reduce the toxicity of these nanoparticles.

  7. A simple urea-based route to ternary metal oxynitride nanoparticles

    SciTech Connect

    Gomathi, A.; Reshma, S.; Rao, C.N.R.

    2009-01-15

    Ternary metal oxynitrides are generally prepared by heating the corresponding metal oxides with ammonia for long durations at high temperatures. In order to find a simple route that avoids use of gaseous ammonia, we have employed urea as the nitriding agent. In this method, ternary metal oxynitrides are obtained by heating the corresponding metal carbonates and transition metal oxides with excess urea. By this route, ternary metal oxynitrides of the formulae MTaO{sub 2}N (M=Ca, Sr or Ba), MNbO{sub 2}N (M=Sr or Ba), LaTiO{sub 2}N and SrMoO{sub 3-x}N{sub x} have been prepared successfully. The oxynitrides so obtained were generally in the form of nanoparticles, and were characterized by various physical techniques. - Graphical abstract: Nanoparticles of ternary metal oxynitrides can be synthesized by means of urea route. Given is the TEM image of the nanoparticles of CaTaO{sub 2}N so obtained and the insets show the SAED pattern and HREM image of the nanoparticles.

  8. Dialkyldiselenophosphinato-metal complexes - a new class of single source precursors for deposition of metal selenide thin films and nanoparticles

    NASA Astrophysics Data System (ADS)

    Malik, Sajid N.; Akhtar, Masood; Revaprasadu, Neerish; Qadeer Malik, Abdul; Azad Malik, Mohammad

    2014-08-01

    We report here a new synthetic approach for convenient and high yield synthesis of dialkyldiselenophosphinato-metal complexes. A number of diphenyldiselenophosphinato-metal as well as diisopropyldiselenophosphinato-metal complexes have been synthesized and used as precursors for deposition of semiconductor thin films and nanoparticles. Cubic Cu2-xSe and tetragonal CuInSe2 thin films have been deposited by AACVD at 400, 450 and 500 °C whereas cubic PbSe and tetragonal CZTSe thin films have been deposited through doctor blade method followed by annealing. SEM investigations revealed significant differences in morphology of the films deposited at different temperatures. Preparation of Cu2-xSe and In2Se3 nanoparticles using diisopropyldiselenophosphinato-metal precursors has been carried out by colloidal method in HDA/TOP system. Cu2-xSe nanoparticles (grown at 250 °C) and In2Se3 nanoparticles (grown at 270 °C) have a mean diameter of 5.0 ± 1.2 nm and 13 ± 2.5 nm, respectively.

  9. Carbon Materials Metal/Metal Oxide Nanoparticle Composite and Battery Anode Composed of the Same

    NASA Technical Reports Server (NTRS)

    Hung, Ching-Cheh (Inventor)

    2006-01-01

    A method of forming a composite material for use as an anode for a lithium-ion battery is disclosed. The steps include selecting a carbon material as a constituent part of the composite, chemically treating the selected carbon material to receive nanoparticles, incorporating nanoparticles into the chemically treated carbon material and removing surface nanoparticles from an outside surface of the carbon material with incorporated nanoparticles. A material making up the nanoparticles alloys with lithium.

  10. Facile approach for large-scale production of metal and metal oxide nanoparticles and preparation of antibacterial cotton pads.

    PubMed

    Shankar, Shiv; Rhim, Jong-Whan

    2017-05-01

    Metallic nanoparticles such as zinc oxide (ZnONPs), copper oxide (CuONPs), and silver (AgNPs) were synthesized in gram scale using green methods. The antibacterial cotton fibers/nanoparticles (cotton fibers/NPs) composite pads were prepared, and nanoparticle binding/release tests were performed. All the NPs were crystalline and showed characteristic XRD diffraction peaks and showed the characteristic FTIR bands of the respective nanoparticles. All the NPs showed strong antimicrobial activity against Gram-positive and Gram-negative pathogenic bacteria. The NPs were attached to the cotton pad by adsorption at different extent depending on the types of nanoparticles. The adsorption and release of nanoparticles on and from cotton pads were also dependent on the types of nanoparticles. The NPs-adsorbed cotton pads showed potent antibacterial activity against pathogenic bacteria such as Escherichia coli, Listeria monocytogenes, Staphylococcus aureus, and Staphylococcus epidermis. The developed NPs-adsorbed cotton pads have potential to be used as wound dressings and antibacterial food packaging applications.

  11. Ultrafast dynamics via coherent exciton-plasmon coupling in quantum dot-metallic nanoparticle systems

    NASA Astrophysics Data System (ADS)

    Sadeghi, S. M.

    2015-08-01

    When a quantum dot is in the vicinity of a metallic nanoparticle and is driven by a laser field, quantum coherence can renormalize the plasmon field of the metallic nanoparticle, forming a coherent-plasmonic field (CP field). We demonstrate that for a given form of variation of this laser field with time, the CP field around the metallic nanoparticle can offer different forms of ultrafast field dynamics, depending on the location. In other words, we show the coherent exciton-plasmon coupling in such a system allows it to act as coherent nanoantenna capable of generation position-dependent coherent-plasmonic dynamics, designating each location around the metallic nanoparticle with characteristic time-position coordinates. These investigations are carried out by demonstrating that the coherent dynamics responsible for these effects can persist in the presence of the ultrafast polarization dephasing of the quantum dots. This highlights the prospect of generation and preservation of quantum coherence effects in hybrid quantum dot-metallic nanoparticle systems at elevated temperatures. Therefore, even when the decoherence times of the quantum dots are of the order of several hundreds of femtoseconds, as observed at room temperature, such coherent dynamics can remain quite distinct and observable.

  12. Robust Synthesis of Ciprofloxacin-Capped Metallic Nanoparticles and Their Urease Inhibitory Assay.

    PubMed

    Nisar, Muhammad; Khan, Shujaat Ali; Qayum, Mughal; Khan, Ajmal; Farooq, Umar; Jaafar, Hawa Z E; Zia-Ul-Haq, Muhammad; Ali, Rashid

    2016-03-25

    The fluoroquinolone antibacterial drug ciprofloxacin (cip) has been used to cap metallic (silver and gold) nanoparticles by a robust one pot synthetic method under optimized conditions, using NaBH₄ as a mild reducing agent. Metallic nanoparticles (MNPs) showed constancy against variations in pH, table salt (NaCl) solution, and heat. Capping with metal ions (Ag/Au-cip) has significant implications for the solubility, pharmacokinetics and bioavailability of fluoroquinolone molecules. The metallic nanoparticles were characterized by several techniques such as ultraviolet visible spectroscopy (UV), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) methods. The nanoparticles synthesized using silver and gold were subjected to energy dispersive X-ray tests in order to show their metallic composition. The NH moiety of the piperazine group capped the Ag/Au surfaces, as revealed by spectroscopic studies. The synthesized nanoparticles were also assessed for urease inhibition potential. Fascinatingly, both Ag-cip and Au-cip NPs exhibited significant urease enzyme inhibitory potential, with IC50 = 1.181 ± 0.02 µg/mL and 52.55 ± 2.3 µg/mL, compared to ciprofloxacin (IC50 = 82.95 ± 1.62 µg/mL). MNPs also exhibited significant antibacterial activity against selected bacterial strains.

  13. Continuous Polyol Synthesis of Metal and Metal Oxide Nanoparticles Using a Segmented Flow Tubular Reactor (SFTR).

    PubMed

    Testino, Andrea; Pilger, Frank; Lucchini, Mattia Alberto; Quinsaat, Jose Enrico Q; Stähli, Christoph; Bowen, Paul

    2015-06-08

    Over the last years a new type of tubular plug flow reactor, the segmented flow tubular reactor (SFTR), has proven its versatility and robustness through the water-based synthesis of precipitates as varied as CaCO3, BaTiO3, Mn(1-x)NixC2O4·2H2O, YBa oxalates, copper oxalate, ZnS, ZnO, iron oxides, and TiO2 produced with a high powder quality (phase composition, particle size, and shape) and high reproducibility. The SFTR has been developed to overcome the classical problems of powder production scale-up from batch processes, which are mainly linked with mass and heat transfer. Recently, the SFTR concept has been further developed and applied for the synthesis of metals, metal oxides, and salts in form of nano- or micro-particles in organic solvents. This has been done by increasing the working temperature and modifying the particle carrying solvent. In this paper we summarize the experimental results for four materials prepared according to the polyol synthesis route combined with the SFTR. CeO2, Ni, Ag, and Ca3(PO4)2 nanoparticles (NPs) can be obtained with a production rate of about 1-10 g per h. The production was carried out for several hours with constant product quality. These findings further corroborate the reliability and versatility of the SFTR for high throughput powder production.

  14. Potential for metal contamination by direct sonication of nanoparticle suspensions

    EPA Science Inventory

    There is a growing need to examine the potential toxicity of engineered nanoparticles (ENPs) to establish regulations protective of environmental health and safety. During a series of experiments to evaluate the toxicity of titanium dioxide (TiO2) nanoparticles on terrestrial pla...

  15. A method of producing very high resistivity surface conduction on ceramic accelerator components using metal ion implantation

    SciTech Connect

    F. Liu; I. Brown; L. Phillips; G. Biallas; T. Siggins

    1997-05-01

    An important technique used for the suppression of surface flashover on high voltage DC ceramic insulators as well as for RF windows is that of providing some surface conduction to bleed off accumulated surface charge. The authors have used metal ion implantation to modify the surface of high voltage ceramic vacuum insulators to provide a uniform surface resistivity of approximately 5 x 10{sup 10} Q{sup 2}. A vacuum arc ion source based implanter was used to implant Pt at an energy of about 135 MeV to doses of up to more than 5 x 10{sup 16} ions cm{sup 2} into small ceramic test coupons and also into the inside surface of several ceramic accelerator columns 25 cm I. D. by 28 cm long. Here they describe the experimental set-up used to do the ion implantation and summarize the results of their exploratory work on implantation into test coupons as well as the implantations of the actual ceramic columns.

  16. Moving metal artifact reduction in cone-beam CT scans with implanted cylindrical gold markers

    SciTech Connect

    Toftegaard, Jakob Fledelius, Walther; Worm, Esben S.; Poulsen, Per R.; Seghers, Dieter; Huber, Michael; Brehm, Marcus; Elstrøm, Ulrik V.

    2014-12-15

    Purpose: Implanted gold markers for image-guided radiotherapy lead to streaking artifacts in cone-beam CT (CBCT) scans. Several methods for metal artifact reduction (MAR) have been published, but they all fail in scans with large motion. Here the authors propose and investigate a method for automatic moving metal artifact reduction (MMAR) in CBCT scans with cylindrical gold markers. Methods: The MMAR CBCT reconstruction method has six steps. (1) Automatic segmentation of the cylindrical markers in the CBCT projections. (2) Removal of each marker in the projections by replacing the pixels within a masked area with interpolated values. (3) Reconstruction of a marker-free CBCT volume from the manipulated CBCT projections. (4) Reconstruction of a standard CBCT volume with metal artifacts from the original CBCT projections. (5) Estimation of the three-dimensional (3D) trajectory during CBCT acquisition for each marker based on the segmentation in Step 1, and identification of the smallest ellipsoidal volume that encompasses 95% of the visited 3D positions. (6) Generation of the final MMAR CBCT reconstruction from the marker-free CBCT volume of Step 3 by replacing the voxels in the 95% ellipsoid with the corresponding voxels of the standard CBCT volume of Step 4. The MMAR reconstruction was performed retrospectively using a half-fan CBCT scan for 29 consecutive stereotactic body radiation therapy patients with 2–3 gold markers implanted in the liver. The metal artifacts of the MMAR reconstructions were scored and compared with a standard MAR reconstruction by counting the streaks and by calculating the standard deviation of the Hounsfield units in a region around each marker. Results: The markers were found with the same autosegmentation settings in 27 CBCT scans, while two scans needed slightly changed settings to find all markers automatically in Step 1 of the MMAR method. MMAR resulted in 15 scans with no streaking artifacts, 11 scans with 1–4 streaks, and 3 scans

  17. Metal alloy and monoelemental nanoclusters in silica formed by sequential ion implantation and annealing in selected atmosphere

    NASA Astrophysics Data System (ADS)

    Ren, F.; Jiang, C. Z.; Chen, H. B.; Shi, Y.; liu, C.; Wang, J. B.

    2004-11-01

    The preparation of metal alloy and monoelemental nanoclusters in silica by Ag, Cu ion sequential implantation and annealing in selected oxidizing or reducing atmosphere is studied. The formation of metastable Ag-Cu alloy is verified in the as-implanted samples by optical absorption spectra, selected area electron diffraction and energy dispersive spectrometer spectrum. The alloy is discomposed at elevated annealing temperature in both oxidizing and reducing atmospheres. The different effects of annealing behaviors on the Ag-Cu alloy nanoclusters are investigated.

  18. Optical second harmonic generation of single metallic nanoparticles embedded in a homogeneous medium.

    PubMed

    Butet, Jérémy; Duboisset, Julien; Bachelier, Guillaume; Russier-Antoine, Isabelle; Benichou, Emmanuel; Jonin, Christian; Brevet, Pierre-François

    2010-05-12

    We report the optical second harmonic generation from individual 150 nm diameter gold nanoparticles dispersed in gelatin. The quadratic hyperpolarizability of the particles is determined and the input polarization dependence of the second harmonic intensity obtained. These results are found in excellent agreement with ensemble measurements and finite element simulations. These results open up new perspectives for the investigation of the nonlinear optical properties of noble metal nanoparticles.

  19. Optical steering of thermally generated microbubbles in a liquid for targeted metallic nanoparticle delivery

    NASA Astrophysics Data System (ADS)

    Krishnappa, Arjun; Abeywickrema, Ujitha; Banerjee, Partha

    2016-09-01

    A novel mathematical model is developed to investigate the behavior of thermally generated microbubbles in the presence of optical radiation to understand the mechanism of their steering. Forces acting on a bubble are studied in detail using a general force model. It has been proposed that these microbubbles with agglomerated metallic nanoparticles can be used for targeted drug delivery. The model can be extended to include the steering of bubbles with agglomerated silver or gold nanoparticles on their surface.

  20. Metal ions to control the morphology of semiconductor nanoparticles: copper selenide nanocubes.

    PubMed

    Li, Wenhua; Zamani, Reza; Ibáñez, Maria; Cadavid, Doris; Shavel, Alexey; Morante, Joan Ramon; Arbiol, Jordi; Cabot, Andreu

    2013-03-27

    Morphology is a key parameter in the design of novel nanocrystals and nanomaterials with controlled functional properties. Here, we demonstrate the potential of foreign metal ions to tune the morphology of colloidal semiconductor nanoparticles. We illustrate the underlying mechanism by preparing copper selenide nanocubes in the presence of Al ions. We further characterize the plasmonic properties of the obtained nanocrystals and demonstrate their potential as a platform to produce cubic nanoparticles with different composition by cation exchange.

  1. Removal of Heavy Metals from Aqueous Systems with Thiol Functionalized Superparamagnetic Nanoparticles

    SciTech Connect

    Yantasee, Wassana; Warner, Cynthia L.; Sangvanich, Thanapon; Addleman, Raymond S.; Carter, Timothy G.; Wiacek, Robert J.; Fryxell, Glen E.; Timchalk, Chuck; Warner, Marvin G.

    2007-06-09

    We have shown that superparamagnetic iron oxide (Fe3O4) nanoparticles with a surface functionalization of dimercaptosuccinic acid is an effective, magnetic, sorbent material for toxic metals such as Hg, Ag, Pb, Cd and other soft cations. The chemical affinity, stability, capacity and kinetics of the functionalized nanoparticles has been explored and compared to conventional resin based sorbents and nanoporous silica materials with similar surface chemistries.

  2. Plasmonic and Catalytic Properties of Shape-Controlled Metal Nanoparticles and their Assemblies

    NASA Astrophysics Data System (ADS)

    Klinkova, Anna

    This work explores the effect of the shape of metal nanoscale building blocks on the structural, optical, and plasmonic properties of their assemblies, as well as on the catalytic performance and hydrogen interactions of individual nanoparticles with specific shapes. In Chapter 3, I describe the linear self-assembly of bifunctional metal nanoparticles in the presence of monofunctional nanoscale chain stoppers. Chain stoppers with controlled reactivity were synthesized allowing control over the morphology of the self-assembled structures. Analysis of the degree of polymerization of linear nanostructures provided information about self-assembly kinetics, side reactions, and the distribution of species in the reaction. This work facilitated testing of theoretical models developed for molecular polymerization and fabrication of linear nanoparticle assemblies with controllable properties. In Chapter 4, I developed linear solution-based self-assembly of cubic metal nanoparticles, examined the morphology of the nanocube chains and their optical characteristics. In comparison with chains of nanospheres with similar dimensions, compositions, and surface chemistry, predominant face-to-face assembly of nanocubes leads to a larger volume of plasmonic hot spots, uniform electromagnetic field enhancement in the gaps between nanocubes, and a new coupling mode for nanocube chains, associated with Fabry-Perot structure. In Chapter 5, I investigated plasmon-mediated enhancement of the catalysis by palladium-based nanoparticles with different shapes and composition, bearing surface plasmon resonance in visible range. The photocatalytic activity of palladium-based nanoparticles depended more on their shape than internal structure. These findings pave the way for the design of palladium nanocatalysts with enhanced performance acting under visible light illumination. In Chapter 6, I developed a facile scaled-up synthesis of monodisperse palladium nanoparticles with various shapes

  3. Structure and optical properties of noble metal and oxide nanoparticles dispersed in various polysaccharide biopolymers

    NASA Astrophysics Data System (ADS)

    Djoković, V.; Božanic, D. K.; Vodnik, V. V.; Krsmanović, R. M.; Trandafilovic, L. V.; Dimitrijević-Branković, S.

    2011-10-01

    We present the results on the structure and the optical properties of noble metal (Ag, Au) and oxide (ZnO) nanoparticles synthesized by various methods in different polysaccharide matrices such as chitosan, glycogen, alginate and starch. The structure of the obtained nanoparticles was studied in detail with microscopic techniques (TEM, SEM), while the XPS spectroscopy was used to investigate the effects at the nanoparticle-biomolecule interfaces. The antimicrobial activity of the nanocomposite films with Ag nanoparticles was tested against the Staphylococcus aureus, Escherichia coli and Candida albicans pathogens. In addition, we will present the results on the structure and optical properties of the tryptophan amino acid functionalized silver nanoparticles dispersed in water soluble polymer matrices.

  4. High-Performance, Superparamagnetic, Nanoparticle-Based Heavy Metal Sorbents for Removal of Contaminants from Natural Waters

    SciTech Connect

    Warner, Cynthia L.; Addleman, Shane; Cinson, Anthony D.; Droubay, Timothy C.; Engelhard, Mark H.; Nash, Michael A.; Yantasee, Wassana; Warner, Marvin G.

    2010-06-01

    We describe the synthesis and characterization of superparamagnetic iron oxide nanoparticle based heavy metal sorbents with various surface chemistries that demonstrate an excellent affinity for the separation of heavy metals in contaminated water systems (i.e. spiked Columbia river water). The magnetic nanoparticle sorbents are prepared from an easy to synthesize iron oxide precursor, followed by a simple, one-step ligand exchange technique to introduce the organic surface functionality of interest chosen to target either specific or broader classes of heavy metals. Functionalized superparamagnetic nanoparticles are excellent sorbent materials for the extraction of heavy metal contaminants from environmental and clinical samples since they are easily removed from the media once bound to the contaminant by simply applying a magnetic field. These engineered magnetic nanoparticle sorbents have an inherently high active surface area (often > 100 m2/g), allowing for increased binding capacity. To demonstrate the potential sorbent performance of each of the surface modified magnetic nanoparticles, river water was spiked with Hg, Pb, Cd, Ag, Co, Cu, and Tl and exposed to low concentrations of the functionalized nanoparticles. The samples were analyzed to determine the metal content before and after exposure to the magnetic nanoparticle sorbents. In almost all cases reported here the nanoparticles were found to be superior to commercially available sorbents binding a wide range of different heavy metals with extremely high affinity. Detailed characterization of the functionalized magnetic nanoparticle sorbents including FT-IR, BET surface analysis, TGA, XPS and VSM as well as the heavy metal removal experiments are presented.

  5. Assessment of magnetic field interactions and radiofrequency-radiation-induced heating of metallic spinal implants in 7 T field.

    PubMed

    Tsukimura, Itsuko; Murakami, Hideki; Sasaki, Makoto; Endo, Hirooki; Yamabe, Daisuke; Oikawa, Ryosuke; Doita, Minoru

    2016-10-21

    The safety of metallic spinal implants in magnetic resonance imaging (MRI) performed using ultrahigh fields has not been established. Hence, we examined whether the displacement forces caused by a static magnetic field and the heating induced by radiofrequency radiation are substantial for spinal implants in a 7 T field. We investigated spinal rods of various lengths and materials, a screw, and a cross-linking bridge in accordance with the American Society for Testing and Materials guidelines. The displacement forces of the metallic implants in static 7 T and 3 T static magnetic fields were measured and compared. The temperature changes of the implants during 15-min-long fast spin-echo and balanced gradient-echo image acquisition sequences were measured in the 7 T field. The deflection angles of the metallic spinal materials in the 7 T field were 5.0-21.0° [median: 6.7°], significantly larger than those in the 3 T field (1.0-6.3° [2.2°]). Among the metallic rods, the cobalt-chrome rods had significantly larger deflection angles (17.8-21.0° [19.8°]) than the pure titanium and titanium alloy rods (5.0-7.7° [6.2°]). The temperature changes of the implants, including the cross-linked rods, were 0.7-1.0°C [0.8°C] and 0.6-1.0°C [0.7°C] during the fast spin-echo and balanced gradient-echo sequences, respectively; these changes were slightly larger than those of the controls (0.4-1.1°C [0.5°C] and 0.3-0.9°C [0.6°C], respectively). All of the metallic spinal implants exhibited small displacement forces and minimal heating, indicating that MRI examinations using 7 T fields may be performed safely on patients with these implants. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

  6. Where does the toxicity of metal oxide nanoparticles come from: The nanoparticles, the ions, or a combination of both?

    PubMed

    Wang, Dali; Lin, Zhifen; Wang, Ting; Yao, Zhifeng; Qin, Mengnan; Zheng, Shourong; Lu, Wei

    2016-05-05

    The toxicity of metal oxide nanoparticles (NPs) has aroused great concern over the past few years. However, there still remains the question whether the toxicity of the metal oxide NPs originates from the released ions or the NPs themselves. In this study, the metal ion release of CuO, Fe2O3, ZnO, Co3O4, Cr2O3, and NiO NPs in aqueous media was investigated, and their contributions to the metal oxide NPs' inhibition on the bioluminescence of Photobacterium phosphoreum were studied. It was found that the ions release of the metal oxide NPs in aqueous media was complex, depending on both the dissolution and adsorption processes of the metal oxide NPs. The relationships between the metal oxide NPs' antibacterial effects and their released metal ions could be divided into three categories: (1) the ZnO NPs' antibacterial effect was due solely to the released Zn(2+); (2) the CuO NPs' antibacterial effect originated from both the released Cu(2+),and the CuO particles; and (3) the antibacterial effects of Fe2O3, Co3O4, Cr2O3, and NiO NPs were caused by the NPs themselves. Our findings suggest that the ions release and their contributions to the NPs' toxicity should be considered in the toxicity evaluations of the metal oxide NPs.

  7. Size Effects in the Catalytic Activity of Unsupported Metallic Nanoparticles

    NASA Astrophysics Data System (ADS)

    Weber, Alfred P.; Seipenbusch, Martin; Kasper, Gerhard

    2003-08-01

    The influence of the size of nanoparticles on their catalytic activity was investigated for two systems on unsupported, i.e. gasborne nanoparticles. For the oxidation of hydrogen on Pt nanoparticle agglomerates, transport processes had to be taken into account to extract the real nanoparticle size effects. The results indicate an optimum particle size for the catalytic activity below 5nm which points clearly toward a real volume effect. In the case of the methanation reaction on gasborne Ni nanoparticles, no transport limitations were observed and the product concentration was directly proportional to the activity of the primary particles. We found an activity maximum for particles of about 19nm in diameter. This size is too large to be attributed to a real nanoparticle size effect induced by the electronic band structure. Therefore, we concluded that the particle size influences the adsorption behavior of the carbon monoxide molecules. In fact, it is known that intermediate adsorption enthalpies may favor dissociation processes, which is an essential step for the reaction, as manifested in the so called volcano-shaped curve. Then, in addition to the material dependence of the adsorption, we would also encounter a direct size dependence in the case of methanation on gasborne Ni nanoparticles.

  8. Charge transport and absorption study of metal nanoparticle plasmonics for organic photovoltaics

    NASA Astrophysics Data System (ADS)

    Xue, Mei; Zhu, Jinfeng; Shen, Huajun; Kim, Seongku; Ho, Jack J.; Qasem, Hussam Aldeen S.; Otaibi, Zaid S. Al; Wang, Kang L.; Device Research Laboratory, Ucla Team; Kacst/California Institute Of Excellence On Green Nanotechnology Team

    2011-03-01

    A hybrid plasmonic nanostructure of an optically sensitive heterojunction organic film incorporating metal nanoparticles is fabricated. From the Charge Extraction in Linearly Increasing Voltage (CELIV) measurements, the mobility of this hybrid plasmonic nanostructure has been experimentally extracted to be at least one order of the magnitude higher than that of the organic film without metal nanoparticles. The measured absorption spectrum also shows the increasing of the intensity by around 28% as well as the broadening of the spectrum. The theoretical calculation confirms this broadband optical absorption enhancement results from localized surface plasmon resonance. The optimization of the density of the metal nanoparticles has been done to achieve the best performance for the photovoltaic devices. This work is supported in part by KACST/California Institute of Excellence on Green Nanotechnology.

  9. Nonlinear optical absorption and stimulated Mie scattering in metallic nanoparticle suspensions

    NASA Astrophysics Data System (ADS)

    He, Guang S.; Law, Wing-Cheung; Baev, Alexander; Liu, Sha; Swihart, Mark T.; Prasad, Paras N.

    2013-01-01

    The nonlinear optical properties of four metallic (Au-, Au/Ag-, Ag-, and Pt-) nanoparticle suspensions in toluene have been studied in both femtosecond and nanosecond regimes. Nonlinear transmission measurements in the femtosecond laser regime revealed two-photon absorption (2PA) induced nonlinear attenuation, while in the nanosecond laser regime a stronger nonlinear attenuation is due to both 2PA and 2PA-induced excited-state absorption. In the nanosecond regime, at input pump laser intensities above a certain threshold value, a new type of stimulated (Mie) scattering has been observed. Being essentially different from all other well known molecular (Raman, Brillouin) stimulated scattering effects, the newly observed stimulated Mie scattering from the metallic nanoparticles exhibits the features of no frequency shift and low pump threshold requirement. A physical model of induced Bragg grating initiated by the backward Mie scattering from metallic nanoparticles is proposed to explain the gain mechanism of the observed stimulated scattering effect.

  10. Spectral properties of a strongly coupled quantum-dot-metal-nanoparticle system

    NASA Astrophysics Data System (ADS)

    Hakami, Jabir; Wang, Ligang; Zubairy, M. Suhail

    2014-05-01

    We investigate the coherent control of the quantum optical properties of a quantum dot coupled to a metallic nanoparticle using a photon Green's function method, which is based on the exact quantization of the electromagnetic fields in a dissipative medium. The properties of the spontaneous emission spectra of such a system are studied in detail with and without involving the coherent field. The Rabi splitting effect in the spectrum emitted by the quantum dot under particular conditions is predicted for different sizes of the metal nanoparticles. We show that the spontaneous emission spectra of the transition coupled to surface plasmons may be further modified by adjusting the external coherent control on the adjacent transitions. Furthermore, the pronounced oscillatory behavior for the quantum-dot dynamics is demonstrated with the presence of the metal nanoparticle by the non-Markovian treatment. Our results may have potential applications in plasmonic-based quantum manipulation.

  11. Quantum bio-nanosensors based on quantum dot-metallic nanoparticle systems

    NASA Astrophysics Data System (ADS)

    Sadeghi, S. M.

    2013-03-01

    When metallic nanoparticles are put in the vicinity of semiconductor quantum dots and driven by a coherent light source, their intrinsic plasmonic fields can be replaced with a new type of fields (coherent-plasmonic fields). These fields are generated via coherent coupling of excitons in quantum dots and localized surface plasmon resonances (LSPRs). We show the coherent-plasmonic field of a metallic nanoparticle can lead to a significantly larger field enhancement than that caused by its LSPR. Utilizing this, we investigate how such a coherent field enhancement can improve the sensitivities plasmonic nanosensors for detection single biological molecules. The results demonstrate application of quantum coherence in quantum dot-metallic nanoparticle systems for chemical and biological sensing applications.

  12. Plasmonic electromagnetically induced transparency in metallic nanoparticle-quantum dot hybrid systems

    NASA Astrophysics Data System (ADS)

    Hatef, Ali; Sadeghi, Seyed M.; Singh, Mahi R.

    2012-02-01

    We study the variation of the energy absorption rate in a hybrid semiconductor quantum dot-metallic nanoparticle system doped in a photonic crystal. The quantum dot is taken as a three-level V-configuration system and is driven by two applied fields (probe and control). We consider that one of the excitonic resonance frequencies is near to the plasmonic resonance frequency of the metallic nanoparticle, and is driven by the probe field. The other excitonic resonance frequency is far from both the plasmonic resonance frequency and the photonic bandgap edge, and is driven by the control field. In the absence of the photonic crystal we found that the system supports three excitonic-induced transparencies in the energy absorption spectrum of the metallic nanoparticle. We show that the photonic crystal allows us to manipulate the frequencies of such excitonic-induced transparencies and the amplitude of the energy absorption rate.

  13. Core shell hybrids based on noble metal nanoparticles and conjugated polymers: synthesis and characterization

    NASA Astrophysics Data System (ADS)

    Fratoddi, Ilaria; Venditti, Iole; Battocchio, Chiara; Polzonetti, Giovanni; Cametti, Cesare; Russo, Maria Vittoria

    2011-12-01

    Noble metal nanoparticles of different sizes and shapes combined with conjugated functional polymers give rise to advanced core shell hybrids with interesting physical characteristics and potential applications in sensors or cancer therapy. In this paper, a versatile and facile synthesis of core shell systems based on noble metal nanoparticles (AuNPs, AgNPs, PtNPs), coated by copolymers belonging to the class of substituted polyacetylenes has been developed. The polymeric shells containing functionalities such as phenyl, ammonium, or thiol pending groups have been chosen in order to tune hydrophilic and hydrophobic properties and solubility of the target core shell hybrids. The Au, Ag, or Pt nanoparticles coated by poly(dimethylpropargylamonium chloride), or poly(phenylacetylene-co-allylmercaptan). The chemical structure of polymeric shell, size and size distribution and optical properties of hybrids have been assessed. The mean diameter of the metal core has been measured (about 10-30 nm) with polymeric shell of about 2 nm.

  14. A review of chemical and physical characterisation of atmospheric metallic nanoparticles

    NASA Astrophysics Data System (ADS)

    Sanderson, Paul; Delgado-Saborit, Juana Maria; Harrison, Roy M.

    2014-09-01

    Knowledge of the human health impacts associated with airborne nanoparticle exposure has led to considerable research activity aimed at better characterising these particles and understanding which particle properties are most important in the context of effects on health. Knowledge of the sources, chemical composition, physical structure and ambient concentrations of nanoparticles has improved significantly as a result. Given the known toxicity of many metals and the contribution of nanoparticles to their oxidative potential, the metallic content of the nanoparticulate burden is likely to be an important factor to consider when attempting to assess the impact of nanoparticle exposure on health. This review therefore seeks to draw together the existing knowledge of metallic nanoparticles in the atmosphere and discuss future research priorities in the field. The article opens by outlining the reasons behind the current research interest in the field, and moves on to discuss sources of nanoparticles to the atmosphere. The next section reviews ambient concentrations, covering spatial and temporal variation, mass and number size distributions, air sampling and measurement techniques. Further sections discuss the chemical and physical composition of particles. The review concludes by summing up the current state of research in the area and considering where future research should be focused.

  15. Structural determination of metal nanoparticles from their vibrational (phonon) density of states

    NASA Astrophysics Data System (ADS)

    Garzon, Ignacio; Sauceda, Huziel

    2015-03-01

    The vibrational (phonon) density of states of metal nanoparticles with size between 2-6 nm can be measured using nuclear resonant inelastic x-ray or plasmon resonance Raman scattering. In this work, we present atomistic calculations, based on a semiempirical tight-binding many-body Gupta potential, of the vibrational density of states (VDOS) for FCC, decahedral, and icosahedral (ICO) gold and silver nanoparticles with sizes ~ 4 nm (~ 2000 atoms). The calculated VDOS are compared with experimental data, recently published for gold and silver nanoparticles of similar size, obtained through plasmon resonance Raman scattering. The best agreement between the calculated and measured VDOS's is obtained for the ICO morphology for both metal nanoparticles. These results indicate that most of the nanoparticles in the experimental samples should have icosahedral structures. The present study also shows that, as in the case of molecular systems and small clusters, vibrational spectroscopy of metal nanoparticles with few nanometers in size, together with theoretical calculations, are powerful tools for their structure determination. with your abstract body. Work supported by CONACYT-Mexico under Project 177981.

  16. Comparative study on the uptake and bioimpact of metal nanoparticles released into environment

    NASA Astrophysics Data System (ADS)

    Andries, Maria; Pricop, Daniela; Grigoras, Marian; Lupu, Nicoleta; Sacarescu, Liviu; Creanga, Dorina; Iacomi, Felicia

    2015-12-01

    Metallic particles of very small size are ubiquitously released in the air, water and soil from various natural and artificial sources - the last ones with enhanced extent since nanotechnology development accelerated exponentially. In this study we focused on the impact of metal nanoparticles in vegetal species of agroindustrial interest namely the maize (Zea mais L.). Laboratory simulation of environmental pollution was carried out by using engineered nanoparticles of two types: iron oxides with magnetic properties and gold nanoparticles supplied in the form of dilutes stable suspensions in the culture medium of maize seedlings. Magnetic nanoparticle (MNPs) preparation was performed by applying chemical route from iron ferric and ferrous precursor salts in alkali reaction medium at relatively high temperature (over 80 °C). Gold nanoparticles (GNPs) synthesis was accomplished from auric hydrochloride acid in alkali reaction medium in similar temperature conditions. In both types of metallic nanoparticles citrate ions were used as coating shell with role of suspension stabilization. Plantlet response was assessed at the level of assimilatory pigment contents in green tissue of seedlings in early ontogenetic stages.

  17. Revealing the nanoparticles aspect ratio in the glass-metal nanocomposites irradiated with femtosecond laser

    PubMed Central

    Chervinskii, S.; Drevinskas, R.; Karpov, D. V.; Beresna, M.; Lipovskii, A. A.; Svirko, Yu. P.; Kazansky, P. G.

    2015-01-01

    We studied a femtosecond laser shaping of silver nanoparticles embedded in soda-lime glass. Comparing experimental absorption spectra with the modeling based on Maxwell Garnett approximation modified for spheroidal inclusions, we obtained the mean aspect ratio of the re-shaped silver nanoparticles as a function of the laser fluence. We demonstrated that under our experimental conditions the spherical shape of silver nanoparticles changed to a prolate spheroid with the aspect ratio as high as 3.5 at the laser fluence of 0.6 J/cm2. The developed approach can be employed to control the anisotropy of the glass-metal composites. PMID:26348691

  18. Transition-metal-doped ZnO nanoparticles: synthesis, characterization and photocatalytic activity under UV light.

    PubMed

    Saleh, Rosari; Djaja, Nadia Febiana

    2014-09-15

    ZnO nanoparticles doped with transition metals (Mn and Co) were prepared by a co-precipitation method. The synthesized nanoparticles were characterized using X-ray diffraction, scanning electron microscopy, energy dispersive X-rays, Fourier transform infrared spectroscopy, electron spin resonance spectroscopy and diffuse reflectance spectroscopy. The photocatalytic activities of the transition-metal-doped ZnO nanoparticles were evaluated in the degradation of methyl orange under UV irradiation. ZnO nanoparticles doped with 12 at.% of Mn and Co ions exhibited the maximum photodegradation efficiency. The experiment also demonstrated that the photodegradation efficiency of Mn-doped ZnO nanoparticles was higher than that of Co-doped ZnO nanoparticles. These results indicate that charge trapping states due to the doping were the decisive factor rather than the average particle size and energy gap. Moreover the effect of pH values on the degradation efficiency was discussed in the photocatalytic experiments using 12 at.% Mn- and Co-doped ZnO nanoparticles.

  19. Transition-metal-doped ZnO nanoparticles: Synthesis, characterization and photocatalytic activity under UV light

    NASA Astrophysics Data System (ADS)

    Saleh, Rosari; Djaja, Nadia Febiana

    2014-09-01

    ZnO nanoparticles doped with transition metals (Mn and Co) were prepared by a co-precipitation method. The synthesized nanoparticles were characterized using X-ray diffraction, scanning electron microscopy, energy dispersive X-rays, Fourier transform infrared spectroscopy, electron spin resonance spectroscopy and diffuse reflectance spectroscopy. The photocatalytic activities of the transition-metal-doped ZnO nanoparticles were evaluated in the degradation of methyl orange under UV irradiation. ZnO nanoparticles doped with 12 at.% of Mn and Co ions exhibited the maximum photodegradation efficiency. The experiment also demonstrated that the photodegradation efficiency of Mn-doped ZnO nanoparticles was higher than that of Co-doped ZnO nanoparticles. These results indicate that charge trapping states due to the doping were the decisive factor rather than the average particle size and energy gap. Moreover the effect of pH values on the degradation efficiency was discussed in the photocatalytic experiments using 12 at.% Mn- and Co-doped ZnO nanoparticles.

  20. Tantalum trabecular metal implants in anterior cervical corpectomy and fusion: 2-year prospective analysis.

    PubMed

    King, V; Swart, A; Winder, M J

    2016-10-01

    Anterior cervical decompression for two or more cervical spondylotic levels can be performed using either multiple anterior cervical discectomies and fusion or anterior cervical corpectomy and fusion (ACCF). A variety of options for ACCF implants exist but to our knowledge, there is no clinical data for the use of tantalum trabecular metal implants (TTMI) for ACCF. A retrospective review was performed of prospectively collected data for ten patients undergoing ACCF with TTMI between 2011 and 2012. Radiological outcome was assessed by measuring the change in cervical (C) lordosis (fusion Cobb and C2-C7 Cobb), graft subsidence (anterior/posterior, determined by the subsidence of anterior/posterior body height of fused segments; cranial/caudal, determined by the cranial/caudal plate-to-disc distances) and rate of fusion using lateral cervical X-rays of patients at 0, 6, 12 and 24months post-operatively. The Neck Disability Index (NDI) assessed clinical outcome pre-operatively and at 6, 12 and 24months post-operatively. Cervical lordosis (Cobb angle of fused segment) was 5.2° (± 4.2°) at 0months and 6.0° (± 5.7°) at 24months post-operatively. Graft subsidence was observed to occur at 6months post-operatively and continued throughout follow-up. Anterior, posterior and caudal subsidence occurred more in the first 12months post-operatively than in the following 12months (p<0.05). Average pre-operative NDI was 45%. Average NDIs were 18%, 13% and 10% at 6, 12 and 24months post-operatively, respectively. ACCF patients treated with TTMI demonstrated stable cervical lordosis over 2years of follow-up and 100% fusion rates after 2years. Measures of subsidence appeared to decrease with time. Patients experienced improved clinical outcomes over the 2-year period.