Functionalization of textiles with silver and zinc oxide nanoparticles

NASA Astrophysics Data System (ADS)

Pulit-Prociak, Jolanta; Chwastowski, Jarosław; Kucharski, Arkadiusz; Banach, Marcin

2016-11-01

The paper presents a method for functionalization of textile materials using fabric dyes modified with silver or zinc oxide nanoparticles. Embedding of these nanoparticles into the structure of other materials makes that the final product is characterized by antimicrobial properties. Indigo and commercially available dye were involved in studies. It is worth to note that silver nanoparticles were obtained in-situ in the reaction of preparing indigo dye and in the process of preparing commercial dye baths. Such a method allows reducing technological steps. The modified dyes were used for dyeing of cotton fibers. The antimicrobial properties of final textile materials were studied. Saccharomyces cerevisiae strain was used in microbiological test. The results confirmed biocidal activity of prepared materials.

PtRu nanoparticles embedded in nitrogen doped carbon with highly stable CO tolerance and durability

NASA Astrophysics Data System (ADS)

Ling, Ying; Yang, Zehui; Yang, Jun; Zhang, Yunfeng; Zhang, Quan; Yu, Xinxin; Cai, Weiwei

2018-02-01

As is well known, the lower durability and sluggish methanol oxidation reaction (MOR) of PtRu alloy electrocatalyst blocks the commercialization of direct methanol fuel cells (DMFCs). Here, we design a new PtRu electrocatalyst, with highly stable CO tolerance and durability, in which the PtRu nanoparticles are embedded in nitrogen doped carbon layers derived from carbonization of poly(vinyl pyrrolidone). The newly fabricated electrocatalyst exhibits no loss in electrochemical surface area (ECSA) and MOR activity after potential cycling from 0.6-1.0 V versus reversible hydrogen electrode, while commercial CB/PtRu retains only 50% of its initial ECSA. Meanwhile, due to the same protective layers, the Ru dissolution is decelerated, resulting in stable CO tolerance. Methanol oxidation reaction (MOR) testing indicates that the activity of newly fabricated electrocatalyst is two times higher than that of commercial CB/PtRu, and the fuel cell performance of the embedded PtRu electrocatalyst was comparable to that of commercial CB/PtRu. The embedded PtRu electrocatalyst is applicable in real DMFC operation. This study offers important and useful information for the design and fabrication of durable and CO tolerant electrocatalysts.

Improved out-coupling efficiency of organic light emitting diodes fabricated on a TiO2 planarization layer with embedded Si oxide nanostructures

NASA Astrophysics Data System (ADS)

Sung, Young Hoon; Jung, Pil-Hoon; Han, Kyung-Hoon; Kim, Yang Doo; Kim, Jang-Joo; Lee, Heon

2017-10-01

In order to increase the out-coupling efficiency of organic light emitting diodes, conical Si oxide nanostructures were formed on a glass substrate using nanoimprint lithography with hydrogen silsesquioxane. Then, the substrate was planarized with TiO2 nanoparticles. Since TiO2 nanoparticles have a higher refractive index than Si oxide, the surface of substrate is physically flat, but optically undulated in a manner that enables optical scattering and suppression of total internal reflection. Subsequently, OLEDs formed on a substrate with nanostructured Si oxide and a TiO2 planarization layer exhibit a 25% increase in out-coupling efficiency by suppressing total internal reflection.

Au-HKUST-1 Composite Nanocapsules: Synthesis with a Coordination Replication Strategy and Catalysis on CO Oxidation.

PubMed

Liu, Yongxin; Zhang, Jiali; Song, Lingxiao; Xu, Wenyuan; Guo, Zanru; Yang, Xiaomin; Wu, Xiaoxin; Chen, Xi

2016-09-07

A novel coordination replication of Cu2O redox-template strategy is reported to efficiently fabricate Au-HKUST-1 composite nanocapsule, with a HKUST-1 sandwich shell and an embedded Au nanoparticles layer. The novel synthesis procedure involves forming Au nanoparticles on the surface of Cu2O, transforming partial Cu2O into HKUST-1 shell via coordination replication, and removing the residual Cu2O by acid. The as-prepared Au-HKUST-1 composite nanocapsules displayed high catalytic activity on CO oxidation.

Tailoring plasmonic properties of metal nanoparticle-embedded dielectric thin films: the sandwich method of preparation

NASA Astrophysics Data System (ADS)

Laha, Ranjit; Malar, P.; Osipowicz, Thomas; Kasiviswanathan, S.

2017-09-01

Tailoring of plasmonic properties of metal nanoparticle-embedded dielectric thin films are very crucial for many thin film-based applications. We, herein, investigate the various ways of tuning the plasmonic positions of gold nanoparticles (AuNPs)-embedded indium oxide thin films (Au:IO) through a sequence-specific sandwich method. The sandwich method is a four-step process involving deposition of In2O3 film by magnetron sputtering in first and fourth steps, thermal evaporation of Au on to In2O3 film in second and annealing of Au/In2O3 film in the third step. The Au:IO films were characterized by x-ray diffraction, spectrophotometry and transmission electron microscopy. The size and shape of the embedded nanoparticles were found from Rutherford back-scattering spectrometry. Based on dynamic Maxwell Garnett theory, the observed plasmon resonance position was ascribed to the oblate shape of AuNPs formed in sandwich method. Finally, through experimental data, it was shown that the plasmon resonance position of Au:IO thin films can be tuned by 125 nm. The method shown here can be used to tune the plasmon resonance position over the entire range of visible region for the thin films made from other combinations of metal-dielectric pair.

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.

Co nanoparticles inserted into a porous carbon amorphous matrix: the role of cooling field and temperature on the exchange bias effect.

PubMed

Fernández-García, María Paz; Gorria, Pedro; Sevilla, Marta; Fuertes, Antonio B; Boada, Roberto; Chaboy, Jesús; Aquilanti, Giuliana; Blanco, Jesús A

2011-01-21

We report unusual cooling field dependence of the exchange bias in oxide-coated cobalt nanoparticles embedded within the nanopores of a carbon matrix. The size-distribution of the nanoparticles and the exchange bias coupling observed up to about 200 K between the Co-oxide shell (∼3-4 nm) and the ferromagnetic Co-cores (∼4-6 nm) are the key to understand the magnetic properties of this system. The estimated values of the effective anisotropy constant and saturation magnetization obtained from the fit of the zero-field cooling and field cooling magnetization vs. temperature curves agree quite well with those of the bulk fcc-Co.

Facile and efficient room temperature solid state reaction enabled synthesis of antimony nanoparticles embedded within reduced graphene oxide for enhanced sodium-ion storage

NASA Astrophysics Data System (ADS)

Zhang, Xiukui; Wu, Ping; Jiang, Li; Zhang, Xiaofang; Shi, Hongxia; Zhu, Xiaoshu; Wei, Shaohua; Zhou, Yiming

2018-06-01

Herein, a very simple and cost-effective solid state reaction method is employed to obtain, for the first time, the antimony nanoparticles embedded within reduced graphene oxide matrices (designated as Sb/rGO). By directly grinding antimony chloride and sodium hydroxide together at room temperature in the presence of graphene oxide (GO), Sb4O5Cl2 precursor was quickly obtained, which is evenly incorporated in the graphene oxide matrices. After subsequent chemical reduction by NaBH4, the Sb/rGO composite was successfully synthesized. The as-prepared Sb/rGO composite consists of uniform Sb nanoparticles of sub-20 nm, all of which have been wrapped in and protected by the rGO matrices. The Sb nanoparticles serve as a sufficient sodium ion reservoir while the rGO matrices provide highly efficient pathways for transport of sodium ions and electrons. Moreover, the volume expansion of Sb during sodiation can be buffered in the rGO matrices. As a result, the Sb/rGO composite exhibits excellent electrochemical performance in sodium-ion batteries (SIBs), including an enhanced cycling stability with a highly reversible charge capacity of 455 mA h g-1 after 45 cycles at 100 mA g-1, and a coulombic efficiency exceeding 98% during cycling. The findings in the present work pave the way to not only synthesize the designated promising electrode materials for high performance SIBs, but also thoroughly understand the solid-state reaction.

Magneto-reactance based detection of MnO nanoparticle-embedded Lewis lung carcinoma cells

NASA Astrophysics Data System (ADS)

Devkota, J.; Howell, M.; Mukherjee, P.; Srikanth, H.; Mohapatra, S.; Phan, M. H.

2015-05-01

We demonstrate the capacity of detecting magnetically weak manganese oxide (MnO) nanoparticles and the Lewis lung carcinoma (LLC) cancer cells that have taken up these nanoparticles using a novel biosensor based on the magneto-reactance (MX) effect of a soft ferromagnetic amorphous ribbon with a microhole-patterned surface. While the magnetic moment of the MnO nanoparticles is relatively small, and a magneto-impedance based sensor fails to detect them in solution (0.05 mg/ml manganese oxide lipid micellar nanoparticles) and inside cells at low concentrations (8.25 × 104 cells/ml), the detection of these nanoparticles and the LLC cells containing them is achieved with the MX-based sensor, which, respectively, reaches the detection sensitivity of ˜3.6% and 2.8% as compared to the blank cells. Since the MnO nanoparticles are a promising contrast agent for magnetic resonance imaging (MRI) of lung cells, the MX-based biosensing technique can be developed as a pre-detection method for MRI of lung cancer cells.

Ferrate(VI)-induced arsenite and arsenate removal by in situ structural incorporation into magnetic iron(III) oxide nanoparticles.

PubMed

Prucek, Robert; Tuček, Jiří; Kolařík, Jan; Filip, Jan; Marušák, Zdeněk; Sharma, Virender K; Zbořil, Radek

2013-04-02

We report the first example of arsenite and arsenate removal from water by incorporation of arsenic into the structure of nanocrystalline iron(III) oxide. Specifically, we show the capability to trap arsenic into the crystal structure of γ-Fe2O3 nanoparticles that are in situ formed during treatment of arsenic-bearing water with ferrate(VI). In water, decomposition of potassium ferrate(VI) yields nanoparticles having core-shell nanoarchitecture with a γ-Fe2O3 core and a γ-FeOOH shell. High-resolution X-ray photoelectron spectroscopy and in-field (57)Fe Mössbauer spectroscopy give unambiguous evidence that a significant portion of arsenic is embedded in the tetrahedral sites of the γ-Fe2O3 spinel structure. Microscopic observations also demonstrate the principal effect of As doping on crystal growth as reflected by considerably reduced average particle size and narrower size distribution of the "in-situ" sample with the embedded arsenic compared to the "ex-situ" sample with arsenic exclusively sorbed on the iron oxide nanoparticle surface. Generally, presented results highlight ferrate(VI) as one of the most promising candidates for advanced technologies of arsenic treatment mainly due to its environmentally friendly character, in situ applicability for treatment of both arsenites and arsenates, and contrary to all known competitive technologies, firmly bound part of arsenic preventing its leaching back to the environment. Moreover, As-containing γ-Fe2O3 nanoparticles are strongly magnetic allowing their separation from the environment by application of an external magnet.

Effect of content silver and heat treatment temperature on morphological, optical, and electrical properties of ITO films by sol-gel technique

NASA Astrophysics Data System (ADS)

Mirzaee, Majid; Dolati, Abolghasem

2014-09-01

Silver-doped indium tin oxide thin films were synthesized using sol-gel dip-coating technique. The influence of different silver-dopant contents and annealing temperature on the electrical, optical, structural, and morphological properties of the films were characterized by means of four-point probe, UV-Vis spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and X-ray photoelectron spectroscope (XPS). XRD analysis confirmed the formation of cubic bixbyte structure of In2O3 with silver nanoparticles annealed at 350 °C. XPS analysis showed that divalent tin transformed to tetravalent tin through oxidization, and silver nanoparticles embedded into ITO matrix covered with silver oxide shell, resulting in high quality nanocomposite thin films. The embedment of polyvinylpyrrolidone inhibited the growth of silver nanoparticles and ITO annealed at 350 °C. Delafossite structure of tin-doped AgInO2 was found at higher annealing temperatures. XRD analysis and FESEM micrographs showed that the optimum temperature to prevent the formation of AgInO2 is 350 °C. The embedment of silver particles (5-10 nm) from reduction of silver ion in ITO thin films improved the electrical conductivity and optical transmittance of ITO nanolayers. The lowest stable sheet resistance of 1,952 Ω/Sq for a 321 nm thick and an average optical transmittance of 91.8 % in the visible region with a band gap of 3.43 eV were achieved for silver-doping content of 0.04 M.

Au Nanoparticle Sub-Monolayers Sandwiched between Sol-Gel Oxide Thin Films

PubMed Central

Della Gaspera, Enrico; Menin, Enrico; Sada, Cinzia

2018-01-01

Sub-monolayers of monodisperse Au colloids with different surface coverage have been embedded in between two different metal oxide thin films, combining sol-gel depositions and proper substrates functionalization processes. The synthetized films were TiO2, ZnO, and NiO. X-ray diffraction shows the crystallinity of all the oxides and verifies the nominal surface coverage of Au colloids. The surface plasmon resonance (SPR) of the metal nanoparticles is affected by both bottom and top oxides: in fact, the SPR peak of Au that is sandwiched between two different oxides is centered between the SPR frequencies of Au sub-monolayers covered with only one oxide, suggesting that Au colloids effectively lay in between the two oxide layers. The desired organization of Au nanoparticles and the morphological structure of the prepared multi-layered structures has been confirmed by Rutherford backscattering spectrometry (RBS), Secondary Ion Mass Spectrometry (SIMS), and Scanning Electron Microscopy (SEM) analyses that show a high quality sandwich structure. The multi-layered structures have been also tested as optical gas sensors. PMID:29538338

Improved reaction kinetics and selectivity by the TiO2-embedded carbon nanofiber support for electro-oxidation of ethanol on PtRu nanoparticles

NASA Astrophysics Data System (ADS)

Nakagawa, Nobuyoshi; Ito, Yudai; Tsujiguchi, Takuya; Ishitobi, Hirokazu

2014-02-01

The electro-oxidation of ethanol by the catalyst of PtRu nanoparticles supported on a TiO2-embedded carbon nanofiber (PtRu/TECNF), which has recently been proposed by the authors as a highly active catalyst for methanol oxidation, is investigated by cyclic voltammetry using a glassy carbon electrode and by operating a direct ethanol fuel cell (DEFC) with the catalyst. The mass activity obtained from the cyclic voltammogram for the ethanol oxidation is compared to that for the methanol oxidation reported in our recent paper. The mass activity for the ethanol oxidation is comparable or slightly higher than that for the methanol oxidation, and the relationship between the TECNF composition, i.e., the Ti/C mass ratio, and the activity are also similar to that for the methanol oxidation. A DEFC fabricated with the PtRu/TECNF shows a higher power output compared to that with the commercial PtRu/C catalyst. An analysis of the reaction products by a simple two-step reaction model reveals that the PtRu/TECNF increases the rate constant for the reaction steps from ethanol to acetaldehyde and subsequently to CO2, but decreases that from acetaldehyde to acetic acid. This means that the PtRu/TECNF improves not only the kinetics, but also the selectivity to acetaldehyde.

Characterization of hybrid cobalt-porous silicon systems: protective effect of the Matrix in the metal oxidation

PubMed Central

2012-01-01

In the present work, the characterization of cobalt-porous silicon (Co-PSi) hybrid systems is performed by a combination of magnetic, spectroscopic, and structural techniques. The Co-PSi structures are composed by a columnar matrix of PSi with Co nanoparticles embedded inside, as determined by Transmission Electron Microscopy (TEM). The oxidation state, crystalline structure, and magnetic behavior are determined by X-Ray Absorption Spectroscopy (XAS) and Alternating Gradient Field Magnetometry (AGFM). Additionally, the Co concentration profile inside the matrix has been studied by Rutherford Backscattering Spectroscopy (RBS). It is concluded that the PSi matrix can be tailored to provide the Co nanoparticles with extra protection against oxidation. PMID:22938050

Nanometric study of nickel oxide prepared by sol gel process

NASA Astrophysics Data System (ADS)

Dessai, R. Raut; Desa, J. A. E.; Sen, D.; Babu, P. D.

2018-04-01

Nickel oxide nanopowder was synthesized by sol gel method using nickel nitrate as the starting material. Nickel oxide nanoparticles with a grain size of 15-90 nm have been studied by; small angle neutron scattering; scanning electron microscopy; and vibrating sample magnetometry. A combination of Ferro and paramagnetic behaviour of the particles after calcination at 800 °C is observed while for powder calcined at 400 °C, soft magnetic character with saturation is seen. The system of nanoparticles ofNiO embedded in a silica matrix is also studied for the structural change. Weak magnetic ordering is observed in this case with the likely-hood of particles being evenly distributed in the silica.

Oxide nanomembrane hybrids with enhanced mechano- and thermo-sensitivity for semitransparent epidermal electronics.

PubMed

Park, Minjoon; Do, Kyungsik; Kim, Jaemin; Son, Donghee; Koo, Ja Hoon; Park, Jinkyung; Song, Jun-Kyul; Kim, Ji Hoon; Lee, Minbaek; Hyeon, Taeghwan; Kim, Dae-Hyeong

2015-05-01

Oxide nanomembrane hybrids with enhanced mechano- and thermo-sensitivity for semitransparent epidermal electronics are developed. The use of nanomaterials (single wall nanotubes and silver nanoparticles) embedded in the oxide nanomembranes significantly enhances mechanical and thermal sensitivities. These mechanical and thermal sensors are utilized in wheelchair control and hypothermia detection, which are useful for patients with strokes. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Composite anion-exchangers modified with nanoparticles of hydrated oxides of multivalent metals

NASA Astrophysics Data System (ADS)

Maltseva, T. V.; Kolomiets, E. O.; Dzyazko, Yu. S.; Scherbakov, S.

2018-02-01

Organic-inorganic composite ion-exchangers based on anion exchange resins have been obtained. Particles of one-component and two-component modifier were embedded using the approach, which allows us to realize purposeful control of a size of the embedded particles. The approach is based on Ostwald-Freundlich equation, which was adapted to deposition in ion exchange matrix. The equation was obtained experimentally. Hydrated oxides of zirconium and iron were applied to modification, concentration of the reagents were varied. The embedded particles accelerate sorption, the rate of which is fitted by the model equation of chemical reactions of pseudo-second order. When sorption of arsenate ions from very diluted solution (50 µg dm-3) occurs, the composites show higher distribution coefficients comparing with the pristine resin.

Controlling the Degradation of Bioresorbable Polymers

NASA Astrophysics Data System (ADS)

Moritz, Istvan; Crowley, Brian; Brundage, Elizabeth; Rende, Deniz; Ozisik, Rahmi

Bioresorbable polymers play a vital role in the development of implantable materials that are used in surgical procedures, controlled drug delivery systems; and tissue engineering scaffolds. The half-life of common bioresorbable polymers ranges from 3 to over 12 months and slow bioresorption rates of these polymers restrict their use to a limited set of applications. The use of embedded enzymes was previously proposed to control the degradation rate of bioresorbable polymers, and was shown to decrease average degradation time to about 0.5 months. In this study, electromagnetic actuation of iron oxide magnetic nanoparticles embedded in an encapsulant polymer, poly(ethyleneoxide), PEO, was employed to initiate enzyme assisted degradation of bioresorbable polymer poly(caprolactone), PCL. Results indicate that the internal temperature of iron oxide magnetic nanoparticle doped PEO samples can be increased via an alternating magnetic field, and temperature increase depends strongly on nanoparticle concentration and magnetic field parameters. The temperature achieved is sufficient to relax the PEO matrix and to enable the diffusion of enzymes from PEO to a surrounding PCL matrix. Current studies are directed at measuring the degradation rate of PCL due to the diffused enzyme. This material is based upon work supported by the National Science Foundation under Grant No. CMMI-1538730.

Vertically oriented TiO(x)N(y) nanopillar arrays with embedded Ag nanoparticles for visible-light photocatalysis.

PubMed

Jiang, Weitao; Ullah, Najeeb; Divitini, Giorgio; Ducati, Caterina; Kumar, R Vasant; Ding, Yucheng; Barber, Zoe H

2012-03-27

We present a straightforward method to produce highly crystalline, vertically oriented TiO(x)N(y) nanopillars (up to 1 μm in length) with a band gap in the visible-light region. This process starts with reactive dc sputtering to produce a TiN porous film, followed by a simple oxidation process at elevated temperatures in oxygen or air. By controlling the oxidation conditions, the band gap of the prepared TiO(x)N(y) can be tuned to different wavelength within the range of visible light. Furthermore, in order to inhibit carrier recombination to enhance the photocatalytic activity, Ag nanoparticles have been embedded into the nanogaps between the TiO(x)N(y) pillars by photoinduced reduction of Ag(+) (aq) irradiated with visible light. Transmission electron microscopy reveals that the Ag nanoparticles with a diameter of about 10 nm are uniformly dispersed along the pillars. The prepared TiO(x)N(y) nanopillar matrix and Ag:TiO(x)N(y) network show strong photocatalytic activity under visible-light irradiation, evaluated via degradation of Rhodamine B. © 2012 American Chemical Society

Photoluminescence from Au nanoparticles embedded in Au:oxide composite films

NASA Astrophysics Data System (ADS)

Liao, Hongbo; Wen, Weijia; Wong, George K.

2006-12-01

Au:oxide composite multilayer films with Au nanoparticles sandwiched by oxide layers (such as SiO2, ZnO, and TiO2) were prepared in a magnetron sputtering system. Their photoluminescence (PL) spectra were investigated by employing a micro-Raman system in which an Argon laser with a wavelength of 514 nm was used as the pumping light. Distinct PL peaks located at a wavelength range between 590 and 680 nm were observed in most of our samples, with Au particle size varying from several to hundreds of nanometers. It was found that the surface plasmon resonance (SPR) in these composites exerted a strong influence on the position of the PL peaks but had little effect on the PL intensity.

Co@Co3O4 nanoparticle embedded nitrogen-doped carbon architectures as efficient bicatalysts for oxygen reduction and evolution reactions

NASA Astrophysics Data System (ADS)

Qi, Chunling; Zhang, Li; Xu, Guancheng; Sun, Zhipeng; Zhao, Aihua; Jia, Dianzeng

2018-01-01

The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) play crucial roles in efficient energy conversion and storage solutions. Here, Co@Co3O4 nanoparticle embedded nitrogen-doped carbon architectures (denoted as Co@Co3O4/NCs) are prepared via a simple two-step and in situ approach by carbonization and subsequent oxidation of Co-MOF containing high contents of carbon and nitrogen. When evaluated as electrocatalyst towards both ORR and OER in a KOH electrolyte solution, the as-fabricated Co@Co3O4/NC-2 exhibits similar ORR catalytic activity to the commercial Pt/C catalyst, but superior stability and good methanol tolerance. Furthermore, the as-fabricated catalysts also show promising catalytic activity for OER. The effective catalytic activities originate from the synergistic effects between well wrapped Co@Co3O4 nanoparticles and nitrogen doped carbon structures.

Ferric oxide quantum dots in stable phosphate glass system and their magneto-optical study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garaje, Sunil N.; Apte, Sanjay K.; Kumar, Ganpathy

2013-02-15

Graphical abstract: We report synthesis of ferric oxide embedded low melting phosphate glass nanocomposite and also the effect of ferric oxide nanoparticles (NCs) content on the optical and magneto-optical properties of the glasses. Faraday rotation of the glass nanocomposites was measured and showed variation in Verdet constant with concentration of ferric oxide. Interestingly, the host glass itself showed fairly good Verdet constant (11.5°/T cm) and there is a threefold enhancement in the Verdet constant of ferric oxide quantum dot-glass nanocomposite. Highlights: ► We synthesize ferric oxide embedded low melting stable phosphate glass nanocomposite. ► Glasses doped with 0.25 and 2%more » ferric oxide show particle size in the range of 4–12 nm. ► The host phosphate glass itself shows fairly good Verdet constant (11.5°/T cm). ► Glasses doped with 0.25% ferric oxide show high Verdet constant (30.525°/T cm). ► The as synthesis glasses may have potential application in magneto optical devices. -- Abstract: Herein, we report the synthesis of ferric oxide embedded low melting phosphate glass nanocomposite and also the effect of ferric oxide nanoparticles content on the optical and magneto-optical properties of the glasses. The optical study clearly showed red shift in optical cut off with increasing ferric oxide concentration. The band gap of the host glass was observed to be 3.48 eV and it shifted to 3.14 eV after doping with ferric oxide. The glasses doped with 0.25 and 2% ferric oxide showed particle size of 4–6 nm and 8–12 nm, respectively. Faraday rotation of the glass nanocomposites was measured and showed variation in the Verdet constant as per increasing concentration of ferric oxide. Interestingly, the host glass itself showed fairly good Verdet constant (11.5°/T cm) and threefold enhancement was observed in the Verdet constant of ferric oxide quantum dot-glass nanocomposite.« less

Polymer film-nanoparticle composites as new multimodality, non-migrating breast biopsy markers.

PubMed

Kaplan, Jonah A; Grinstaff, Mark W; Bloch, B Nicolas

2016-03-01

To develop a breast biopsy marker that resists fast and slow migration and has permanent visibility under commonly used imaging modalities. A polymer-nanoparticle composite film was prepared by embedding superparamagnetic iron oxide nanoparticles and a superelastic Nitinol wire within a flexible polyethylene matrix. MRI, mammography, and ultrasound were used to visualize the marker in agar, ex vivo chicken breast, bovine liver, brisket, and biopsy training phantoms. Fast migration caused by the "accordion effect" was quantified after simulated stereotactic, vacuum-assisted core biopsy/marker placement, and centrifugation was used to simulate accelerated long-term (i.e., slow) migration in ex vivo bovine tissue phantoms. Clear marker visualization under MRI, mammography, and ultrasound was observed. After deployment, the marker partially unfolds to give a geometrically constrained structure preventing fast and slow migration. The marker can be deployed through an 11G introducer without fast migration occurring, and shows substantially less slow migration than conventional markers. The polymer-nanoparticle composite biopsy marker is clearly visible on all clinical imaging modalities and does not show substantial migration, which ensures multimodal assessment of the correct spatial information of the biopsy site, allowing for more accurate diagnosis and treatment planning and improved breast cancer patient care. Polymer-nanoparticle composite biopsy markers are visualized using ultrasound, MRI, and mammography. Embedded iron oxide nanoparticles provide tuneable contrast for MRI visualization. Permanent ultrasound visibility is achieved with a non-biodegradable polymer having a distinct ultrasound signal. Flexible polymer-based biopsy markers undergo shape change upon deployment to minimize migration. Non-migrating multimodal markers will help improve accuracy of pre/post-treatment planning studies.

Iron oxide nanoparticles for magnetically-guided and magnetically-responsive drug delivery.

PubMed

Estelrich, Joan; Escribano, Elvira; Queralt, Josep; Busquets, Maria Antònia

2015-04-10

In this review, we discuss the recent advances in and problems with the use of magnetically-guided and magnetically-responsive nanoparticles in drug delivery and magnetofection. In magnetically-guided nanoparticles, a constant external magnetic field is used to transport magnetic nanoparticles loaded with drugs to a specific site within the body or to increase the transfection capacity. Magnetofection is the delivery of nucleic acids under the influence of a magnetic field acting on nucleic acid vectors that are associated with magnetic nanoparticles. In magnetically-responsive nanoparticles, magnetic nanoparticles are encapsulated or embedded in a larger colloidal structure that carries a drug. In this last case, an alternating magnetic field can modify the structure of the colloid, thereby providing spatial and temporal control over drug release.

Iron Oxide Nanoparticles for Magnetically-Guided and Magnetically-Responsive Drug Delivery

PubMed Central

Estelrich, Joan; Escribano, Elvira; Queralt, Josep; Busquets, Maria Antònia

2015-01-01

In this review, we discuss the recent advances in and problems with the use of magnetically-guided and magnetically-responsive nanoparticles in drug delivery and magnetofection. In magnetically-guided nanoparticles, a constant external magnetic field is used to transport magnetic nanoparticles loaded with drugs to a specific site within the body or to increase the transfection capacity. Magnetofection is the delivery of nucleic acids under the influence of a magnetic field acting on nucleic acid vectors that are associated with magnetic nanoparticles. In magnetically-responsive nanoparticles, magnetic nanoparticles are encapsulated or embedded in a larger colloidal structure that carries a drug. In this last case, an alternating magnetic field can modify the structure of the colloid, thereby providing spatial and temporal control over drug release. PMID:25867479

Structural determination of Bi-doped magnetite multifunctional nanoparticles for contrast imaging.

PubMed

Laguna-Marco, M A; Piquer, C; Roca, A G; Boada, R; Andrés-Vergés, M; Veintemillas-Verdaguer, S; Serna, C J; Iadecola, A; Chaboy, J

2014-09-14

To determine with precision how Bi atoms are distributed in Bi-doped iron oxide nanoparticles their structural characterization has been carried out by X-ray absorption spectroscopy (XAS) recorded at the K edge of Fe and at the L3 edge of Bi. The inorganic nanoparticles are nominally hybrid structures integrating an iron oxide core and a bismuth oxide shell. Fe K-edge XAS indicates the formation of a structurally ordered, non-stoichiometric magnetite (Fe3-δO4) phase for all the nanoparticles. The XAS spectra show that, in the samples synthesized by precipitation in aqueous media and laser pyrolysis, the Bi atoms neither enter into the iron oxide spinel lattice nor form any other mixed Bi-Fe oxides. No modification of the local structure around the Fe atoms induced by the Bi atoms is observed at the Fe K edge. In addition, contrary to expectations, our results indicate that the Bi atoms do not form a well-defined Bi oxide structure. The XAS study at the Bi L3 edge indicates that the environment around Bi atoms is highly disordered and only a first oxygen coordination shell is observed. Indefinite [BiO6-x(OH)x] units (isolated or aggregated forming tiny amorphous clusters) bonded through hydroxyl bridges to the nanoparticle, rather than a well defined Bi2O3 shell, surround the nanoparticle. On the other hand, the XAS study indicates that, in the samples synthesized by thermal decomposition, the Bi atoms are embedded in a longer range ordered structure showing the first and second neighbors.

Highly sensitive colorimetric detection of glucose in a serum based on DNA-embeded Au@Ag core-shell nanoparticles

NASA Astrophysics Data System (ADS)

Kang, Fei; Hou, Xiangshu; Xu, Kun

2015-10-01

Glucose is a key energy substance in diverse biology and closely related to the life activities of the organism. To develop a simple and sensitive method for glucose detection is extremely urgent but still remains a key challenge. Herein, we report a colorimetric glucose sensor in a homogeneous system based on DNA-embedded core-shell Au@Ag nanoparticles. In this assay, a glucose substrate was first catalytically oxidized by glucose oxidase to produce H2O2 which would further oxidize and gradually etch the outer silver shell of Au@Ag nanoparticles. Afterwards, the solution color changed from yellow to red and the surface plasmon resonance (SPR) band of Au@Ag nanoparticles declined and red-shifted from 430 to 516 nm. Compared with previous silver-based glucose colorimetric detection strategies, the distinctive SPR band change is superior to the color variation, which is critical to the high sensitivity of this assay. Benefiting from the outstanding optical property, robust stability and well-dispersion of the core-shell Au@AgNPs hybrid, this colorimetric assay obtained a detection limit of glucose as low as 10 nM, which is at least a 10-fold improvement over other AgNPs-based procedures. Moreover, this optical biosensor was successfully employed to the determination of glucose in fetal bovine serum.

Local Charge Injection and Extraction on Surface-Modified Al2O3 Nanoparticles in LDPE.

PubMed

Borgani, Riccardo; Pallon, Love K H; Hedenqvist, Mikael S; Gedde, Ulf W; Haviland, David B

2016-09-14

We use a recently developed scanning probe technique to image with high spatial resolution the injection and extraction of charge around individual surface-modified aluminum oxide nanoparticles embedded in a low-density polyethylene (LDPE) matrix. We find that the experimental results are consistent with a simple band structure model where localized electronic states are available in the band gap (trap states) in the vicinity of the nanoparticles. This work offers experimental support to a previously proposed mechanism for enhanced insulating properties of nanocomposite LDPE and provides a powerful experimental tool to further investigate such properties.

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.

Electrical properties of films of zinc oxide nanoparticles and its hybrid with reduced graphene oxide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Madhuri, K. Priya; Bramhaiah, K.; John, Neena S., E-mail: jsneena@cnsms.res.in

Free-standing films of ZnO nanoparticles (NPs) and reduced graphene oxide (rGO)-ZnO NPs hybrid are prepared at a liquid/liquid interface. The films are characterized by UV-visible spectroscopy, X-ray diffraction, scanning electron microscopy and atomic force microscopy. ZnO film consists of spherical aggregated NPs while the hybrid film contains folded sheets of rGO with embedded ZnO NPs. Electrical properties of the films and its photoresponse in presence of UV radiation are investigated using current sensing atomic force microscopy (CSAFM) at nanoscale and bulk measurements using two probe methods. Enhancement in photocurrent is observed in both cases and the current imaging reveals anmore » inhomogeneous contribution by different ZnO grains in the film.« less

Cluster synthesis of monodisperse rutile-TiO2 nanoparticles and dielectric TiO2-vinylidene fluoride oligomer nanocomposites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Balasubramanian, B; Kraemer, KL; Valloppilly, SR

2011-09-13

The embedding of oxide nanoparticles in polymer matrices produces a greatly enhanced dielectric response by combining the high dielectric strength and low loss of suitable host polymers with the high electric polarizability of nanoparticles. The fabrication of oxide-polymer nanocomposites with well-controlled distributions of nanoparticles is, however, challenging due to the thermodynamic and kinetic barriers between the polymer matrix and nanoparticle fillers. In the present study, monodisperse TiO2 nanoparticles having an average particle size of 14.4 nm and predominant rutile phase were produced using a cluster-deposition technique without high-temperature thermal annealing and subsequently coated with uniform vinylidene fluoride oligomer (VDFO) moleculesmore » using a thermal evaporation source, prior to deposition as TiO2-VDFO nanocomposite films on suitable substrates. The molecular coatings on TiO2 nanoparticles serve two purposes, namely to prevent the TiO2 nanoparticles from contacting each other and to couple the nanoparticle polarization to the matrix. Parallel-plate capacitors made of TiO2-VDFO nanocomposite film as the dielectric exhibit minimum dielectric dispersion and low dielectric loss. Dielectric measurements also show an enhanced effective dielectric constant in TiO2-VDFO nanocomposites as compared to that of pure VDFO. This study demonstrates for the first time a unique electroactive particle coating in the form of a ferroelectric VDFO that has high-temperature stability as compared to conventionally used polymers for fabricating dielectric oxide-polymer nanocomposites.« less

Rapid, in Situ Synthesis of High Capacity Battery Anodes through High Temperature Radiation-Based Thermal Shock.

PubMed

Chen, Yanan; Li, Yiju; Wang, Yanbin; Fu, Kun; Danner, Valencia A; Dai, Jiaqi; Lacey, Steven D; Yao, Yonggang; Hu, Liangbing

2016-09-14

High capacity battery electrodes require nanosized components to avoid pulverization associated with volume changes during the charge-discharge process. Additionally, these nanosized electrodes need an electronically conductive matrix to facilitate electron transport. Here, for the first time, we report a rapid thermal shock process using high-temperature radiative heating to fabricate a conductive reduced graphene oxide (RGO) composite with silicon nanoparticles. Silicon (Si) particles on the order of a few micrometers are initially embedded in the RGO host and in situ transformed into 10-15 nm nanoparticles in less than a minute through radiative heating. The as-prepared composites of ultrafine Si nanoparticles embedded in a RGO matrix show great performance as a Li-ion battery (LIB) anode. The in situ nanoparticle synthesis method can also be adopted for other high capacity battery anode materials including tin (Sn) and aluminum (Al). This method for synthesizing high capacity anodes in a RGO matrix can be envisioned for roll-to-roll nanomanufacturing due to the ease and scalability of this high-temperature radiative heating process.

Mild in situ growth of platinum nanoparticles on multiwalled carbon nanotube-poly (vinyl alcohol) hydrogel electrode for glucose electrochemical oxidation

NASA Astrophysics Data System (ADS)

Liu, Shumin; Zheng, Yudong; Qiao, Kun; Su, Lei; Sanghera, Amendeep; Song, Wenhui; Yue, Lina; Sun, Yi

2015-12-01

This investigation describes an effective strategy to fabricate an electrochemically active hybrid hydrogel made from platinum nanoparticles that are highly dense, uniformly dispersed, and tightly embedded throughout the conducting hydrogel network for the electrochemical oxidation of glucose. A suspension of multiwalled carbon nanotubes and polyvinyl alcohol aqueous was coated on glassy carbon electrode by electrophoretic deposition and then physically crosslinked to form a three-dimensional porous conductive hydrogel network by a process of freezing and thawing. The network offered 3D interconnected mass-transport channels (around 200 nm) and confined nanotemplates for in situ growth of uniform platinum nanoparticles via the moderate reduction agent, ascorbic acid. The resulting hybrid hydrogel electrode membrane demonstrates an effective method for loading platinum nanoparticles on multiwalled carbon nanotubes by the electrostatic adsorption between multiwalled carbon nanotubes and platinum ions within porous hydrogel network. The average diameter of platinum nanoparticles is 37 ± 14 nm, which is less than the particle size by only using the moderate reduction agent. The hybrid hydrogel electrode membrane-coated glassy carbon electrode showed excellent electrocatalytic activity and good long-term stability toward glucose electrochemical oxidation. The glucose oxidation current exhibited a linear relationship with the concentration of glucose in the presence of chloride ions, promising for potential applications of implantable biofuel cells, biosensors, and electronic devices.

Highly Stretchable and Conductive Silver Nanoparticle Embedded Graphene Flake Electrode Prepared by In situ Dual Reduction Reaction.

PubMed

Yoon, Yeoheung; Samanta, Khokan; Lee, Hanleem; Lee, Keunsik; Tiwari, Anand P; Lee, JiHun; Yang, Junghee; Lee, Hyoyoung

2015-09-18

The emergence of stretchable devices that combine with conductive properties offers new exciting opportunities for wearable applications. Here, a novel, convenient and inexpensive solution process was demonstrated to prepare in situ silver (Ag) or platinum (Pt) nanoparticles (NPs)-embedded rGO hybrid materials using formic acid duality in the presence of AgNO3 or H2PtCl6 at low temperature. The reduction duality of the formic acid can convert graphene oxide (GO) to rGO and simultaneously deposit the positively charged metal ion to metal NP on rGO while the formic acid itself is converted to a CO2 evolving gas that is eco-friendly. The AgNP-embedded rGO hybrid electrode on an elastomeric substrate exhibited superior stretchable properties including a maximum conductivity of 3012 S cm(-1) (at 0 % strain) and 322.8 S cm(-1) (at 35 % strain). Its fabrication process using a printing method is scalable. Surprisingly, the electrode can survive even in continuous stretching cycles.

Photothermal heating as a methodology for post processing of polymeric nanofibers

NASA Astrophysics Data System (ADS)

Gorga, Russell; Clarke, Laura; Bochinski, Jason; Viswanath, Vidya; Maity, Somsubhra; Dong, Ju; Firestone, Gabriel

2015-03-01

Metal nanoparticles embedded within polymeric systems can be made to act as localized heat sources thereby aiding in-situ polymer processing. This is made possible by the surface plasmon resonance (SPR) mediated photothermal effect of metal (in this case gold) nanoparticles, wherein incident light absorbed by the nanoparticle generates a non-equilibrium electron distribution which subsequently transfers this energy into the surrounding medium, resulting in a temperature increase in the immediate region around the particle. Here we demonstrate this effect in polymer nanocomposite systems, specifically electrospun polyethylene oxide nanofibrous mats, which have been annealed at temperatures above the glass transition. A non-contact temperature measurement technique utilizing embedded fluorophores (perylene) has been used to monitor the average temperature within samples. The effect of annealing methods (conventional and photothermal) and annealing conditions (temperature and time) on the fiber morphology, overall crystallinity, and mechanical properties is discussed. This methodology is further utilized in core-sheath nanofibers to crosslink the core material, which is a pre-cured epoxy thermoset. NSF Grant CMMI-1069108.

Nickel nanoparticles-embedded N-doped carbon nanotubes as a biocompatible electrocatalyst in a water splitting-biosynthetic hybrid system for CO2 conversion.

PubMed

Li, Zhongjian; Li, Gang; Chen, Xinlu; Xia, Zheng; Yao, Jiani; Yang, Bin; Lei, Lecheng; Hou, Yang

2018-05-29

CO2 reduction has drawn increasing attention due to the concern of global warming. Water splitting-biosynthetic hybrid systems are novel and efficient approaches for CO2 conversion. Intimate coupling of electrocatalysts and biosynthesis requires the catalysts possess both high catalytic performance and excellent biocompatibility, which is a bottleneck of developing such catalysts. Here, a novel Ni nanoparticles-embedded N-doped carbon nanotubes (Ni@N-C) complex was synthesized as a hydrogen evolution reaction electrocatalyst and was coupled with a hydrogen-oxidizing autotroph, Cupriavidus necator H16, to convert CO2 to poly-β-hydroxybutyrate. In the Ni@N-C, the Ni nanoparticles were encapsulated in N-C nanotubes, which prevented bacteria from direct contact with Ni and inhibited Ni2+ leaching. As a result, Ni@N-C exhibited excellent biocompatibility and stability. This work demonstrates electrocatalysts and biosynthesis can be intimately coupled via rational catalyst design. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fabrication of three-dimensionally interconnected nanoparticle superlattices and their lithium-ion storage properties

PubMed Central

Jiao, Yucong; Han, Dandan; Ding, Yi; Zhang, Xianfeng; Guo, Guannan; Hu, Jianhua; Yang, Dong; Dong, Angang

2015-01-01

Three-dimensional superlattices consisting of nanoparticles represent a new class of condensed materials with collective properties arising from coupling interactions between close-packed nanoparticles. Despite recent advances in self-assembly of nanoparticle superlattices, the constituent materials have been limited to those that are attainable as monodisperse nanoparticles. In addition, self-assembled nanoparticle superlattices are generally weakly coupled due to the surface-coating ligands. Here we report the fabrication of three-dimensionally interconnected nanoparticle superlattices with face-centered cubic symmetry without the presynthesis of the constituent nanoparticles. We show that mesoporous carbon frameworks derived from self-assembled supercrystals can be used as a robust matrix for the growth of nanoparticle superlattices with diverse compositions. The resulting interconnected nanoparticle superlattices embedded in a carbon matrix are particularly suitable for energy storage applications. We demonstrate this by incorporating tin oxide nanoparticle superlattices as anode materials for lithium-ion batteries, and the resulting electrochemical performance is attributable to their unique architectures. PMID:25739732

Multiple functionalities of Ni nanoparticles embedded in carboxymethyl guar gum polymer: catalytic activity and superparamagnetism

NASA Astrophysics Data System (ADS)

Sardar, Debasmita; Sengupta, Manideepa; Bordoloi, Ankur; Ahmed, Md. A.; Neogi, S. K.; Bandyopadhyay, Sudipta; Jain, Ruchi; Gopinath, Chinnakonda S.; Bala, Tanushree

2017-05-01

Composites comprising of metallic nanoparticles in polymer matrices have allured significant importance due to multifunctionalities. Here a simple protocol has been described to embed Ni nanoparticles in carboxymethyl guar gum (CMGG) polymer. The composite formation helps in the stabilization of Ni nanoparticles which are otherwise prone towards aerial oxidation. Further the nanoparticles retain their superparamagnetic nature and catalytic capacity. Ni-Polymer composite catalyses the reduction of 4-Nitrophenol to 4-Aminophenol very efficiently in presence of NaBH4, attaining a complete conversion under some experimental conditions. Ni-Polymer composite is well characterized using UV-vis spectroscopy, FTIR, XPS, powder XRD, TGA, SEM and TEM. A detailed magnetic measurement using superconducting quantum interference device-vibrating sample magnetometer (SQUID-VSM) reveals superparamagnetic behaviour of the composite.

PLA coated paper containing active inorganic nanoparticles: Material characterization and fate of nanoparticles in the paper recycling process.

PubMed

Zhang, Hai; Bussini, Daniele; Hortal, Mercedes; Elegir, Graziano; Mendes, Joana; Jordá Beneyto, Maria

2016-06-01

For paper and paperboard packaging, recyclability plays an important role in conserving the resources and reducing the environmental impacts. Therefore, when it comes to the nano-enabled paper packaging material, the recyclability issue should be properly addressed. This study represents our first report on the fate of nanomaterials in paper recycling process. The packaging material of concern is a PLA (Polylactic Acid) coated paper incorporating zinc oxide nanoparticles in the coating layer. The material was characterised and assessed in a lab-scale paper recycling line. The recyclability test was based on a method adapted from ATICELCA MC501-13, which enabled to recover over 99% of the solids material. The mass balance result indicates that 86-91% zinc oxide nanoparticles ended up in the rejected material stream, mostly embedded within the polymer coating; whereas 7-16% nanoparticles ended up in the accepted material stream. Besides, the tensile strength of the recycled handsheets suggests that the nano-enabled coating had no negative impacts on the recovered fibre quality. Copyright © 2016 Elsevier Ltd. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Janeoo, Shashi; Sharma, Mamta, E-mail: mamta.phy85@gmail.com; Goswamy, J.

Polyaniline-indium oxide (In{sub 2}O{sub 3}/PANI) nanocomposite have been prepared by in-situ polymerization of aniline and as-synthesized In{sub 2}O{sub 3} nanoparticles. X-ray diffraction (XRD), Transmission electron microscopy (TEM), Fourier transformation infrared (FTIR) and UV/Vis spectroscopy techniques are used to investigate the structural and optical properties of In{sub 2}O{sub 3}/PANI nanocomposite. TEM analysis shows In{sub 2}O{sub 3} nanoparticles are embedded in PANI nanofibers. FTIR spectra show the good interactions between PANI nanofibers and In{sub 2}O{sub 3} nanoparticles. The band gap and electronic transitions in In{sub 2}O{sub 3}/PANI nanocomposite is determined by using UV/Vis spectra.

Gold nanoparticles-decorated fluoroalkylsilane nano-assemblies for electrocatalytic applications

NASA Astrophysics Data System (ADS)

Ballarin, Barbara; Barreca, Davide; Cassani, Maria Cristina; Carraro, Giorgio; Maccato, Chiara; Mignani, Adriana; Lazzari, Dario; Bertola, Maurizio

2016-01-01

Metal/organosilane/oxide sandwich structures were prepared via a two-step self-assembly method. First, indium tin oxide (ITO) substrates were functionalized with the following fluoroalkylsilanes (FAS): RFC(O)N(H)(CH2)3Si(OMe)3 (1, RF = C5F11), containing an embedded amide between the perfluoroalkyl chain and the syloxanic moiety, and RF(CH2)2Si(OEt)3 (2, RF = C6F13). Subsequently, Au nanoparticles (AuNPs) introduction in the obtained systems was carried out by controlled immersion into a solution of citrate-stabilized AuNPs. The physico-chemical properties of the target materials were thoroughly investigated by using various complementary techniques. Finally, the application of such systems as catalysts for methanol electro-oxidation under alkaline conditions was investigated, revealing the synergistical role played by FAS and AuNPs in promoting a remarkable electrocatalytic activity.

Embedding ultrafine ZnSnO3 nanoparticles into reduced graphene oxide composites as high-performance electrodes for lithium ion batteries

NASA Astrophysics Data System (ADS)

Ma, Yuhang; Jiang, Ranran; Li, Dan; Dong, Yutao; Liu, Yushan; Zhang, Jianmin

2018-05-01

Ultrafine ZnSnO3 nanoparticles, with an average diameter of 45 nm, homogeneously grown on reduced graphene oxide (rGO) have been successfully fabricated via methods of low temperature coprecipitation, colloid electrostatic self-assembly, and hydrothermal treatment. The uniformly distributed ZnSnO3 nanocrystals could inhibit the restacking of rGO sheets. In turn, the existence of rGO could hinder the growth and aggregation of ZnSnO3 nanoparticles in the synthesis process, increase the conductivity of the composite, and buffer the volume expansion of the ZnSnO3 nanocrystals upon lithium ion insertion and extraction. The obtained ZnSnO3/rGO exhibited superior cycling stability with a discharge/charge capacity of 718/696 mA h g-1 after 100 cycles at a current density of 0.1 A g-1.

Plasma based formation and deposition of metal and metal oxide nanoparticles using a gas aggregation source

NASA Astrophysics Data System (ADS)

Polonskyi, Oleksandr; Ahadi, Amir Mohammad; Peter, Tilo; Fujioka, Kenji; Abraham, Jan Willem; Vasiliauskaite, Egle; Hinz, Alexander; Strunskus, Thomas; Wolf, Sebastian; Bonitz, Michael; Kersten, Holger; Faupel, Franz

2018-05-01

Metal clusters and nanoparticles (NPs) have been studied intensively due to their unique chemical, physical, electrical, and optical properties, resulting from their dimensions, which provided host of applications in nanoscience and nanotechnology. Formation of new materials by embedding NPs into various matrices (i.e. formation of nanocomposites) further expands the horizon of possible application of such nanomaterials. In the last few decades, the focus was put on the formation of metallic and metal oxide NPs via a so-called gas aggregation nanoparticle source employing magnetron sputtering (i.e. Haberland concept). In this paper, an overview is given of the recent progress in formation and deposition of NPs by the gas aggregation method. Examples range from noble metals (Ag, Au) through reactive metals (Al, Ti) to Si and the respective oxides. Emphasis is placed on the mechanism of nanoparticle growth and the resulting properties. Moreover, kinetic Monte Carlo simulations were developed to explain the growth mechanism and dynamics of nanoparticle formation depending on the experimental conditions. In addition, the role of trace amounts of reactive gases and of pulsed operation of the plasma on the nucleation process is addressed. Finally, the treatment of the NPs in the plasma environment resulting in nanoparticle charging, morphological and chemical modifications is discussed. Contribution to the Topical Issue "Fundamentals of Complex Plasmas", edited by Jürgen Meichsner, Michael Bonitz, Holger Fehske, Alexander Piel.

The effect of nanocrystalline silicon host on magnetic properties of encapsulated iron oxide nanoparticles.

PubMed

Granitzer, P; Rumpf, K; Gonzalez-Rodriguez, R; Coffer, J L; Reissner, M

2015-12-21

The purpose of this work is a detailed comparison of the fundamental magnetic properties of nanocomposite systems consisting of Fe3O4 nanoparticle-loaded porous silicon as well as silicon nanotubes. Such composite structures are of potential merit in the area of magnetically guided drug delivery. For magnetic systems to be utilized in biomedical applications, there are certain magnetic properties that must be fulfilled. Therefore magnetic properties of embedded Fe3O4-nanoparticles in these nanostructured silicon host matrices, porous silicon and silicon nanotubes, are investigated. Temperature-dependent magnetic investigations have been carried out for four types of iron oxide particle sizes (4, 5, 8 and 10 nm). The silicon host, in interplay with the iron oxide nanoparticle size, plays a sensitive role. It is shown that Fe3O4 loaded porous silicon and SiNTs differ significantly in their magnetic behavior, especially the transition between superparamagnetic behavior and blocked state, due to host morphology-dependent magnetic interactions. Importantly, it is found that all investigated samples meet the magnetic precondition of possible biomedical applications of exhibiting a negligible magnetic remanence at room temperature.

One-step synthesis and characterization of polyaniline nanofiber/silver nanoparticle composite networks as antibacterial agents.

PubMed

Poyraz, Selcuk; Cerkez, Idris; Huang, Tung Shi; Liu, Zhen; Kang, Litao; Luo, Jujie; Zhang, Xinyu

2014-11-26

Through a facile and effective seeding polymerization reaction via a one-step redox/complexation process, which took place in aqueous medium at ambient temperature, silver nanoparticles (Ag NPs) embedded polyaniline nanofiber (PANI NF) networks were synthesized as antibacterial agents. During the reaction, not only NF morphology formation of the resulting conducting polymers (CPs) but also amplification of the aqueous silver nitrate (AgNO3) solutions' oxidative potentials were managed by vanadium pentoxide (V2O5) sol-gel nanofibers, which acted as well-known nanofibrous seeding agents and the auxiliary oxidative agent at the same time. The PANI/Ag nanocomposites were proven to exhibit excellent antibacterial property against both Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus. Antibacterial property performance and average life span of the nanocomposite network were optimized through the homogeneous distribution/embedment of Ag NPs within one-dimensional (1-D) PANI NF matrix. The antibacterial efficacy tests and nanocomposite material characterization results further indicated that the sole components of PANI/Ag have a synergistic effect to each other in terms of antibacterial property. Thus, this well-known catalytic seeding approach via a one-step oxidative polymerization reaction can be considered as a general methodology and a substantial fabrication tool to synthesize Ag NP decorated nanofibrillar PANI networks as advanced antibacterial agents.

Searching for high-k RE2O3 nanoparticles embedded in SiO2 glass matrix

NASA Astrophysics Data System (ADS)

Mukherjee, S.; Lin, Y. H.; Kao, T. H.; Chou, C. C.; Yang, H. D.

2012-03-01

Significant experimental effort has been explored to search and characterize high-k materials with magnetodielectric effect (MDE) of series of rare earth (RE) oxide (RE2O3) nanoparticles (NPs) embedded in SiO2 glass matrix by a sol-gel route. Properly annealed sol-gel glass (in which RE = Sm, Gd, and Er) shows colossal response of dielectric constant along with diffuse phase transition and MDE around room temperature. The radial distribution functions, reconstructed from extended x-ray absorption fine structure, show the shortening of RE3 + -O depending on the RE2O3 NP size, which is consistent with oxygen vacancy induced dielectric anomaly. The magnetoresistive MDE is very much conditioned by magnetic property of RE2O3 NP grain, the degree of deformation of the lattice and constituent host.

Silver oxide nanoparticles embedded silk fibroin spuns: Microwave mediated preparation, characterization and their synergistic wound healing and anti-bacterial activity.

PubMed

Babu, Punuri Jayasekhar; Doble, Mukesh; Raichur, Ashok M

2018-03-01

The synergistic wound healing and antibacterial activity of silver oxide nanoparticles embedded silk fibroin (Ag 2 O-SF) spuns is reported here. UV-Vis spectro photometric analysis of these spuns showed the surface plasmon resonance (SPR) confirming the formation of the silver oxide nanoparticles (Ag 2 O NPs) on the surface of the silk fibroin (SF). Scanning electron microscope (SEM) and Differential scanning calorimetry (DSC) also confirmed the presence of Ag 2 O NPs on surface of SF. X-ray diffraction (XRD) analysis revealed the crystalline nature of both SF and Ag 2 O-SF. Fourier transform infrared spectroscopy (FT-IR) results showed the different forms of silk (I and II) and their corresponding protein (amide I, II, III) confirmations. Biodegradation study revealed insignificant changes in the morphology of Ag 2 O-SF spuns even after 14 days of immersion in phosphate buffered saline (PBS). Ag 2 O-SF spuns showed excellent antibacterial activity against both pathogen (S. aureus and M. tuberculosis) and non-pathogen (E. coli) bacteria. More importantly, In vitro wound healing (scratch assay) assay revealed fast migration of the T3T fibroblast cells through the scratch area treated with extract of Ag 2 O-SF spuns and the area was completely covered within 24 h. Cytotoxicity assay confirmed the biocompatible nature of the Ag 2 O-SF spuns, thus suggesting an ideal material for wound healing and anti-bacterial applications. Copyright © 2017 Elsevier Inc. All rights reserved.

A simple way to prepare reduced graphene oxide nanosheets/Fe2O3-Pd/N-doped carbon nanosheets and their application in catalysis.

PubMed

Yao, Tongjie; Zhang, Junshuai; Zuo, Quan; Wang, Hao; Wu, Jie; Zhang, Xiao; Cui, Tieyu

2016-04-15

The catalysts with Pd and γ-Fe2O3 nanoparticles embedded between reduced graphene oxide nanosheets (rGS) and N-doped carbon nanosheets (NCS) were prepared through a two-step method. Firstly, graphene oxide nanosheets (GS)/prussian blue (PB)-Pd/polypyrrole (PPy) composites were synthesized by using pyrrole monomer as reductant, K3Fe(CN)6 and PdCl2 as oxidants in the presence of GS via a redox reaction. Subsequently, the as-obtained GS/PB-Pd/PPy composites were calcinated in N2 atmosphere. During the heat-treatment, carbonization of PPy to NCS, conversion of nonmagnetic PB to magnetic γ-Fe2O3 nanoparticles, and reduction of GS to rGS were finished, simultaneously. rGS/Fe2O3-Pd/NCS composites exhibited good catalytic activity toward reduction of 4-nitrophenol. The rate constant k and turnover frequency were calculated and compared with recent reports. Owing to γ-Fe2O3 nanoparticles, the rGS/Fe2O3-Pd/NCS composites could be quickly separated by magnet and reused without obvious decrease in activity. Copyright © 2016 Elsevier Inc. All rights reserved.

Intracellular Trafficking of Silicon Particles and Logic-Embedded Vectors

PubMed Central

Ferrati, Silvia; Mack, Aaron; Chiappini, Ciro; Liu, Xuewu; Bean, Andrew J.; Ferrari, Mauro; Serda, Rita E.

2010-01-01

Mesoporous silicon particles show great promise for use in drug delivery and imaging applications as carriers for second-stage nanoparticles and higher order particles or therapeutics. Modulation of particle geometry, surface chemistry, and porosity allows silicon particles to be optimized for specific applications such as vascular targeting and avoidance of biological barriers commonly found between the site of drug injection and the final destination. In this study, the intracellular trafficking of unloaded carrier silicon particles and carrier particles loaded with secondary iron oxide nanoparticles was investigated. Following cellular uptake, membrane-encapsulated silicon particles migrated to the perinuclear region of the cell by a microtubule-driven mechanism. Surface charge, shape (spherical and hemispherical) and size (1.6 and 3.2 μm) of the particle did not alter the rate of migration. Maturation of the phagosome was associated with an increase in acidity and acquisition of markers of late endosomes and lysosomes. Cellular uptake of iron oxide nanoparticle-loaded silicon particles resulted in sorting of the particles and trafficking to unique destinations. The silicon carriers remained localized in phagosomes, while the second stage iron oxide nanoparticles were sorted into multi-vesicular bodies that dissociated from the phagosome into novel membrane-bound compartments. Release of iron from the cells may represent exocytosis of iron oxide nanoparticle-loaded vesicles. These results reinforce the concept of multi-functional nanocarriers, in which different particles are able to perform specific tasks, in order to deliver single- or multi-component payloads to specific sub-cellular compartments. PMID:20820744

Hierarchical Biosilicates by the 3-D Replication of Block Copolymer Templates in Supercritical Fluids

DTIC Science & Technology

2009-12-30

Iron Oxide Nanoparticles through Supercritical CO2 Infusion of TEOS into Ferritin Doped Block Copolymers…………………………………………………...4 4.2 Simple...which is doped with ferritin (yellow spheres). The blue PPO domains are removed during calcination as is the apoferritin shell, leaving magnetic...iron oxide particles (black) embedded in the mesoporous silica film. 5 2 TEM images of ferritin -containing samples at the specified ferritin

Structural, photoconductivity, and dielectric studies of polythiophene-tin oxide nanocomposites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Murugavel, S., E-mail: starin85@gmail.com; Malathi, M., E-mail: mmalathi@vit.ac.in

2016-09-15

Highlights: • Synthesis of polythiophene-tin oxide nanocomposites confirmed by FTIR and EDAX. • SEM shows SnO{sub 2} nanoparticles embedded within polythiophene matrix. • Stability and isoelectric point suggest nanoparticle–matrix interaction. • High dielectric constant due to high Maxwell–Wagner interfacial polarization. - Abstract: Polythiophene-tinoxide (PT-SnO{sub 2}) nanocomposites were prepared by in situ chemical oxidative polymerization, in the presence of various concentrations of SnO{sub 2} nanoparticles. Samples were characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, thermogravimetric analysis, X-ray photoelectron spectroscopy and Zeta potential measurements. Morphologies and elemental compositions were investigated by transmission electron microscopy, field-emission scanning electron microscopy and energy-dispersive X-ray spectroscopy.more » The photoconductivity of the nanocomposites was studied by field-dependent dark and photo conductivity measurements. Their dielectric properties were investigated using dielectric spectroscopy, in the frequency range of 1kHz–1 MHz. The results indicated that the SnO{sub 2} nanoparticles in the PT-SnO{sub 2} nanocomposite were responsible for its enhanced dielectric performance.« less

Magnetically triggered release of molecular cargo from iron oxide nanoparticle loaded microcapsules

NASA Astrophysics Data System (ADS)

Carregal-Romero, Susana; Guardia, Pablo; Yu, Xiang; Hartmann, Raimo; Pellegrino, Teresa; Parak, Wolfgang J.

2014-12-01

Photothermal release of cargo molecules has been extensively studied for bioapplications. For instance, microcapsules decorated with plasmonic nanoparticles have been widely used in in vitro assays. However, some concerns about their suitability for some in vivo applications cannot be easily overcome, in particular the limited penetration depth of light (even infrared). Magnetic nanoparticles are alternative heat-mediators for local heating, which can be triggered by applying an alternating magnetic field (AMF). AMFs are much less absorbed by tissue than light and thus can penetrate deeper overcoming the above mentioned limitations. Here we present iron oxide nanocube-modified microcapsules as a platform for magnetically triggered molecular release. Layer-by-layer assembled polyelectrolyte microcapsules with 4.6 μm diameter, which had 18 nm diameter iron oxide nanocubes integrated in their walls, were synthesized. The microcapsules were further loaded with an organic fluorescent polymer (Cascade Blue-labelled dextran), which was used as a model of molecular cargo. Through an AMF the magnetic nanoparticles were able to heat their surroundings and destroy the microcapsule walls, leading to a final release of the embedded cargo to the surrounding solution. The cargo release was monitored in solution by measuring the increase in both absorbance and fluorescence signal after the exposure to an AMF. Our results demonstrate that magnetothermal release of the encapsulated material is possible using magnetic nanoparticles with a high heating performance.Photothermal release of cargo molecules has been extensively studied for bioapplications. For instance, microcapsules decorated with plasmonic nanoparticles have been widely used in in vitro assays. However, some concerns about their suitability for some in vivo applications cannot be easily overcome, in particular the limited penetration depth of light (even infrared). Magnetic nanoparticles are alternative heat-mediators for local heating, which can be triggered by applying an alternating magnetic field (AMF). AMFs are much less absorbed by tissue than light and thus can penetrate deeper overcoming the above mentioned limitations. Here we present iron oxide nanocube-modified microcapsules as a platform for magnetically triggered molecular release. Layer-by-layer assembled polyelectrolyte microcapsules with 4.6 μm diameter, which had 18 nm diameter iron oxide nanocubes integrated in their walls, were synthesized. The microcapsules were further loaded with an organic fluorescent polymer (Cascade Blue-labelled dextran), which was used as a model of molecular cargo. Through an AMF the magnetic nanoparticles were able to heat their surroundings and destroy the microcapsule walls, leading to a final release of the embedded cargo to the surrounding solution. The cargo release was monitored in solution by measuring the increase in both absorbance and fluorescence signal after the exposure to an AMF. Our results demonstrate that magnetothermal release of the encapsulated material is possible using magnetic nanoparticles with a high heating performance. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr04055d

Lipid nanoparticle interactions and assemblies

NASA Astrophysics Data System (ADS)

Preiss, Matthew Ryan

Novel liposome-nanoparticle assemblies (LNAs) provide a biologically inspired route for designing multifunctional bionanotheranostics. LNAs combine the benefits of lipids and liposomes to encapsulate, transport, and protect hydrophilic and hydrophobic therapeutics with functional nanoparticles. Functional nanoparticles endow LNAs with additional capabilities, including the ability to target diseases, triggered drug release, controlled therapeutic output, and diagnostic capabilities to produce a drug delivery system that can effectively and efficiently deliver therapeutics while reducing side effects. Not only could LNAs make existing drugs better, they could also provide an avenue to allow once promising non-approved drugs (rejected due to harmful side effects, inadequate pharmacokinetics, and poor efficacy) to be safely used through targeted and controlled delivery directly to the diseased site. LNAs have the potential to be stimuli responsive, delivering drugs on command by external (ultrasound, RF heating, etc.) or internal (pH, blood sugar, heart rate, etc.) stimuli. Individually, lipids and nanoparticles have been clinically approved for therapy, such as Doxil (a liposomal doxorubicin for cancer treatment), and diagnosis, such as Feridex (an iron oxide nanoparticle an MRI contrast enhancement agent for liver tumors). In order to engineer these multifunctional LNAs for theranostic applications, the interactions between nanoparticles and lipids must be better understood. This research sought to explore the formation, design, structures, characteristics, and functions of LNAs. To achieve this goal, different types of LNAs were formed, specifically magnetoliposomes, bilayer decorated LNAs (DLNAs), and lipid-coated magnetic nanoparticles (LMNPs). A fluorescent probe was embedded in the lipid bilayer of magnetoliposomes allowing the local temperature and membrane fluidity to be observed. When subjected to an electromagnetic field that heated the encapsulated iron oxide nanoparticles encapsulated in the lipid bilayer, the local temperature and membrane fluidity could be observed. DLNAs were encapsulated with different sized nanoparticles and concentrations in order to observe the effect of the bilayer nanoparticles on the lipid bilayer's phase behavior and leakage. Two different sized nanoparticles were used, a 2 nm gold nanoparticle (GNP) much smaller than the thickness of the bilayer and a 4 nm GNP near the thickness of the lipid bilayer. The 2 nm GNPs were shown to affect the lipid bilayer differently than the 4 nm GNP. Specifically, the two nanoparticles altered the phase behavior and leakage differently in a temperature dependent fashion, demonstrating that embedded nanoparticle size can be used induce or inhibit bilayer leakage. A dual solvent exchange method was used to control the lipid surface composition of an iron oxide nanoparticle with a cationic lipid and a polyethylene glycol (PEG) lipid to produce lipid coated magnetic nanoparticles (LMNPs). PEG is well known for its ability to enhance the pharmacokinetics of nanostructures by preventing uptake by the immune system. By controlling the lipid surface composition, the surface charge and PEG conformation can be controlled which allowed the LMNPs to be used as an MRI contrast agent and a delivery system for siRNA that could be triggered with temperature.

Localized, plasmon-mediated heating from embedded nanoparticles in nanocomposites

NASA Astrophysics Data System (ADS)

Maity, Somsubhra; Downen, Lori; Bochinski, Jason; Clarke, Laura

2010-03-01

Metallic nanoparticles exhibit a surface plasmon resonance which, when excited with visible light, results in a dramatic increase in the nanoparticle temperature. Previously such localized heating has been primarily employed in biomedical research and other experiments involving aqueous environments. In this work, we investigated use of the nanoparticles in solid phase to re-shape, bond, melt, and otherwise process nanofibrous mats of ˜200 nm diameter nanofibers doped with ˜80 nm spherical gold nanoparticles. Under low light intensities (100 mW/cm^2 @ 532 nm) and dilute nanoparticle loading (˜0.15% volume fraction), irradiation of a few minutes melted nanofibrous mats of poly (ethylene oxide) (Tm = 65 degree C). Control samples without gold nanoparticles displayed no melting. Because the heat is generated from within the material and only at the nanoparticle locations, this technique enables true nanoprocessing -- the non-contact, controlled application of heat at specific nano-sized locations within a material to effect desired local changes. Funded by CMMI-0829379.

Expanded graphite embedded with aluminum nanoparticles as superior thermal conductivity anodes for high-performance lithium-ion batteries

PubMed Central

Zhao, Tingkai; She, Shengfei; Ji, Xianglin; Guo, Xinai; Jin, Wenbo; Zhu, Ruoxing; Dang, Alei; Li, Hao; Li, Tiehu; Wei, Bingqing

2016-01-01

The development of high capacity and long-life lithium-ion batteries is a long-term pursuing and under a close scrutiny. Most of the researches have been focused on exploring electrode materials and structures with high store capability of lithium ions and at the same time with a good electrical conductivity. Thermal conductivity of an electrode material will also have significant impacts on boosting battery capacity and prolonging battery lifetime, which is, however, underestimated. Here, we present the development of an expanded graphite embedded with Al metal nanoparticles (EG-MNPs-Al) synthesized by an oxidation-expansion process. The synthesized EG-MNPs-Al material exhibited a typical hierarchical structure with embedded Al metal nanoparticles into the interspaces of expanded graphite. The parallel thermal conductivity was up to 11.6 W·m−1·K−1 with a bulk density of 453 kg·m−3 at room temperature, a 150% improvement compared to expanded graphite (4.6 W·m−1·K−1) owing to the existence of Al metal nanoparticles. The first reversible capacity of EG-MNPs-Al as anode material for lithium ion battery was 480 mAh·g−1 at a current density of 100 mA·g−1, and retained 84% capacity after 300 cycles. The improved cycling stability and system security of lithium ion batteries is attributed to the excellent thermal conductivity of the EG-MNPs-Al anodes. PMID:27671848

Expanded graphite embedded with aluminum nanoparticles as superior thermal conductivity anodes for high-performance lithium-ion batteries.

PubMed

Zhao, Tingkai; She, Shengfei; Ji, Xianglin; Guo, Xinai; Jin, Wenbo; Zhu, Ruoxing; Dang, Alei; Li, Hao; Li, Tiehu; Wei, Bingqing

2016-09-27

The development of high capacity and long-life lithium-ion batteries is a long-term pursuing and under a close scrutiny. Most of the researches have been focused on exploring electrode materials and structures with high store capability of lithium ions and at the same time with a good electrical conductivity. Thermal conductivity of an electrode material will also have significant impacts on boosting battery capacity and prolonging battery lifetime, which is, however, underestimated. Here, we present the development of an expanded graphite embedded with Al metal nanoparticles (EG-MNPs-Al) synthesized by an oxidation-expansion process. The synthesized EG-MNPs-Al material exhibited a typical hierarchical structure with embedded Al metal nanoparticles into the interspaces of expanded graphite. The parallel thermal conductivity was up to 11.6 W·m -1 ·K -1 with a bulk density of 453 kg·m -3 at room temperature, a 150% improvement compared to expanded graphite (4.6 W·m -1 ·K -1 ) owing to the existence of Al metal nanoparticles. The first reversible capacity of EG-MNPs-Al as anode material for lithium ion battery was 480 mAh·g -1 at a current density of 100 mA·g -1 , and retained 84% capacity after 300 cycles. The improved cycling stability and system security of lithium ion batteries is attributed to the excellent thermal conductivity of the EG-MNPs-Al anodes.

One - Step synthesis of nitrogen doped reduced graphene oxide with NiCo nanoparticles for ethanol oxidation in alkaline media.

PubMed

Kakaei, Karim; Marzang, Kamaran

2016-01-15

Development of anode catalysts and catalyst supporting carbonaceous material containing non-precious metal have attracted tremendous attention in the field of direct ethanol fuel cells (DEFCs). Herein, we report the synthesis and electrochemical properties of nitrogen-doped reduced graphene oxide (NRGO) supported Co, Ni and NiCo nanocomposites. The metal NRGO nanocomposites, in which metal nanoparticles are embedded in the highly porous nitrogen-doped graphene matrix, have been synthesized by simply and one-pot method at a mild temperature using GO, urea choline chloride and urea as reducing and doping agent. The fabricated NiCo/NRGO exhibit remarkable electrocatalytic activity (with Tafel slope of 159.1mVdec(-1)) and high stability for the ethanol oxidation reaction (EOR). The superior performance of the alloy based NRGO is attributed to high surface area, well uniform distribution of high-density nitrogen, metal active sites and synergistic effect. Copyright © 2015 Elsevier Inc. All rights reserved.

Highly Stretchable and Conductive Silver Nanoparticle Embedded Graphene Flake Electrode Prepared by In situ Dual Reduction Reaction

PubMed Central

Yoon, Yeoheung; Samanta, Khokan; Lee, Hanleem; Lee, Keunsik; Tiwari, Anand P.; Lee, JiHun; Yang, Junghee; Lee, Hyoyoung

2015-01-01

The emergence of stretchable devices that combine with conductive properties offers new exciting opportunities for wearable applications. Here, a novel, convenient and inexpensive solution process was demonstrated to prepare in situ silver (Ag) or platinum (Pt) nanoparticles (NPs)-embedded rGO hybrid materials using formic acid duality in the presence of AgNO3 or H2PtCl6 at low temperature. The reduction duality of the formic acid can convert graphene oxide (GO) to rGO and simultaneously deposit the positively charged metal ion to metal NP on rGO while the formic acid itself is converted to a CO2 evolving gas that is eco-friendly. The AgNP-embedded rGO hybrid electrode on an elastomeric substrate exhibited superior stretchable properties including a maximum conductivity of 3012 S cm-1 (at 0 % strain) and 322.8 S cm-1 (at 35 % strain). Its fabrication process using a printing method is scalable. Surprisingly, the electrode can survive even in continuous stretching cycles. PMID:26383845

Highly Stretchable and Conductive Silver Nanoparticle Embedded Graphene Flake Electrode Prepared by In situ Dual Reduction Reaction

NASA Astrophysics Data System (ADS)

Yoon, Yeoheung; Samanta, Khokan; Lee, Hanleem; Lee, Keunsik; Tiwari, Anand P.; Lee, Jihun; Yang, Junghee; Lee, Hyoyoung

2015-09-01

The emergence of stretchable devices that combine with conductive properties offers new exciting opportunities for wearable applications. Here, a novel, convenient and inexpensive solution process was demonstrated to prepare in situ silver (Ag) or platinum (Pt) nanoparticles (NPs)-embedded rGO hybrid materials using formic acid duality in the presence of AgNO3 or H2PtCl6 at low temperature. The reduction duality of the formic acid can convert graphene oxide (GO) to rGO and simultaneously deposit the positively charged metal ion to metal NP on rGO while the formic acid itself is converted to a CO2 evolving gas that is eco-friendly. The AgNP-embedded rGO hybrid electrode on an elastomeric substrate exhibited superior stretchable properties including a maximum conductivity of 3012 S cm-1 (at 0 % strain) and 322.8 S cm-1 (at 35 % strain). Its fabrication process using a printing method is scalable. Surprisingly, the electrode can survive even in continuous stretching cycles.

Plasmonic silicon solar cells: impact of material quality and geometry.

PubMed

Pahud, Celine; Isabella, Olindo; Naqavi, Ali; Haug, Franz-Josef; Zeman, Miro; Herzig, Hans Peter; Ballif, Christophe

2013-09-09

We study n-i-p amorphous silicon solar cells with light-scattering nanoparticles in the back reflector. In one configuration, the particles are fully embedded in the zinc oxide buffer layer; In a second configuration, the particles are placed between the buffer layer and the flat back electrode. We use stencil lithography to produce the same periodic arrangement of the particles and we use the same solar cell structure on top, thus establishing a fair comparison between a novel plasmonic concept and its more traditional counterpart. Both approaches show strong resonances around 700 nm in the external quantum efficiency the position and intensity of which vary strongly with the nanoparticle shape. Moreover, disagreement between simulations and our experimental results suggests that the dielectric data of bulk silver do not correctly represent the reality. A better fit is obtained by introducing a porous interfacial layer between the silver and zinc oxide. Without the interfacial layer, e.g. by improved processing of the nanoparticles, our simulations show that the nanoparticles concept could outperform traditional back reflectors.

Factors Influencing the Stability of Au-Incorporated Metal-Oxide Supported Thin Films for Optical Gas Sensing

DOE PAGES

Baltrus, John P.; Holcomb, Gordon R.; Tylczak, Joseph H.; ...

2017-02-24

There is interest in using Au-nanoparticle incorporated oxide films as functional sensor layers for high-temperature applications in optical-based sensors for measurements in both highly-oxidizing and highly-reducing atmospheres at temperatures approaching 900°C-1000°C because of a relatively high melting temperature combined with the inert nature of Au nanoparticles. This study includes a systematic series of experiments and theoretical calculations targeted at further understanding stability of Au-nanoparticle incorporated TiO 2 films as archetype sensing materials. A combination of thermodynamic modeling and long-term exposure tests were utilized to unambiguously determine that gas stream composition-dependent reactive evaporation of Au (to form predominately Au(g) or AuH(g),more » depending upon the environment) at the surface of the nanoparticles is the dominant mechanism for mass loss of Au. Primary factors dictating the rate of reactive evaporation, and hence the associated film stability, were determined to be the gas stream temperature and the concentration of H 2, with the former playing a more significant role over the ranges of temperatures (700°C - 800°C) and H 2 concentrations (1% to 29% H 2 by volume) explored. The mitigation of Au-mass loss through reactive evaporation was also successfully demonstrated by depositing a SiO 2 overlayer on the Au-nanoparticle embedded films to prevent direct Au-nanoparticle/vapor-phase contact.« less

Factors Influencing the Stability of Au-Incorporated Metal-Oxide Supported Thin Films for Optical Gas Sensing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baltrus, John P.; Holcomb, Gordon R.; Tylczak, Joseph H.

There is interest in using Au-nanoparticle incorporated oxide films as functional sensor layers for high-temperature applications in optical-based sensors for measurements in both highly-oxidizing and highly-reducing atmospheres at temperatures approaching 900°C-1000°C because of a relatively high melting temperature combined with the inert nature of Au nanoparticles. This study includes a systematic series of experiments and theoretical calculations targeted at further understanding stability of Au-nanoparticle incorporated TiO 2 films as archetype sensing materials. A combination of thermodynamic modeling and long-term exposure tests were utilized to unambiguously determine that gas stream composition-dependent reactive evaporation of Au (to form predominately Au(g) or AuH(g),more » depending upon the environment) at the surface of the nanoparticles is the dominant mechanism for mass loss of Au. Primary factors dictating the rate of reactive evaporation, and hence the associated film stability, were determined to be the gas stream temperature and the concentration of H 2, with the former playing a more significant role over the ranges of temperatures (700°C - 800°C) and H 2 concentrations (1% to 29% H 2 by volume) explored. The mitigation of Au-mass loss through reactive evaporation was also successfully demonstrated by depositing a SiO 2 overlayer on the Au-nanoparticle embedded films to prevent direct Au-nanoparticle/vapor-phase contact.« less

Metal Nanoparticles Embedded in Cellulose Nanocrystal Based Films: Material Properties and Post-use Analysis.

PubMed

Lizundia, Erlantz; Goikuria, Uribarri; Vilas, José Luis; Cristofaro, Francesco; Bruni, Giovanna; Fortunati, Elena; Armentano, Ilaria; Visai, Livia; Torre, Luigi

2018-04-25

The dispersion of nanoparticles having different size-, shape-, and composition-dependent properties is an exciting approach to design and synthesize multifunctional materials and devices. This work shows a detailed investigation of the preparation and properties of free-standing nanocomposite films based on cellulose nanocrystals (CNC) loaded with three different types of metal nanoparticles. CNC-based nanocomposites having zinc oxide (ZnO), titanium dioxide (TiO 2 ), and silver oxide (Ag 2 O) have been obtained through evaporation-induced self-assembly (EISA) in acqueous solution. Morphological and optical characteristics, chemical properties, wettability, and antimicrobial assays of the produced films were conducted. Furthermore, disintegrability in composting condition of CNC based nanocomposites was here investigated for the first time. The morphological observations revealed the formation of a chiral nematic structure with uniformly distributed nanoparticles. The bionanocomposite films based on the metal nanoparticles had effective antimicrobial activity, killing both Escherichia coli RB ( E. coli RB) and Staphylococcus aureus 8325-4 ( S. aureus 8325-4). The simplicity method of film preparation, the large quantity of cellulose in the world, and the free-standing nature of the nanocomposite films offer highly advantageous characteristics that can for the new development of multifunctional materials.

Synthesis and applications of MANs/poly(MMA-co-BA) nanocomposite latex by miniemulsion polymerization

PubMed Central

Chen, Huayao; Zhou, Xinhua; Gunasekaran, Sundaram

2017-01-01

We have synthesized core-shell structured 3-methacryloxypropyltrimethoxysilane (MPS) functionalized antimony-doped tin oxide nanoparticles (MANs)–poly(methyl methacrylate-co-butyl acrylate) (PMMA-co-BA, PMB) nanocomposite latex particles via miniemulsion polymerization method. Polymerizable anionic surfactant DNS-86 (allyloxy polyoxyethylene(10) nonyl ammonium sulfate) was first introduced to synthesize core-shell nanocomposite. The morphologies of synthesized MANs and MANs/PMB latex nanocomposite particles were studied with transmission electron microscopy, which revealed particles, on average 70 nm in size, with a core-shell structure. Owing to the uniformity and hydrophobicity of MANs, the MANs-embedded PMB latex nanocomposite can be tailored more precisely than other nanoparticles-embedded nanocomposites. Films incorporating 10 wt% of MANs in the MAN/PMB latex nanocomposite exhibit good transmittance in the visible region, and excellent opacity in the near infrared region. The MANs/PMB nanocomposite film also appears suitable for heat insulation applications. PMID:29291076

Electrocatalytic N-Doped Graphitic Nanofiber - Metal/Metal Oxide Nanoparticle Composites.

PubMed

Tang, Hongjie; Chen, Wei; Wang, Jiangyan; Dugger, Thomas; Cruz, Luz; Kisailus, David

2018-03-01

Carbon-based nanocomposites have shown promising results in replacing commercial Pt/C as high-performance, low cost, nonprecious metal-based oxygen reduction reaction (ORR) catalysts. Developing unique nanostructures of active components (e.g., metal oxides) and carbon materials is essential for their application in next generation electrode materials for fuel cells and metal-air batteries. Herein, a general approach for the production of 1D porous nitrogen-doped graphitic carbon fibers embedded with active ORR components, (M/MO x , i.e., metal or metal oxide nanoparticles) using a facile two-step electrospinning and annealing process is reported. Metal nanoparticles/nanoclusters nucleate within the polymer nanofibers and subsequently catalyze graphitization of the surrounding polymer matrix and following oxidation, create an interconnected graphite-metal oxide framework with large pore channels, considerable active sites, and high specific surface area. The metal/metal oxide@N-doped graphitic carbon fibers, especially Co 3 O 4 , exhibit comparable ORR catalytic activity but superior stability and methanol tolerance versus Pt in alkaline solutions, which can be ascribed to the synergistic chemical coupling effects between Co 3 O 4 and robust 1D porous structures composed of interconnected N-doped graphitic nanocarbon rings. This finding provides a novel insight into the design of functional electrocatalysts using electrospun carbon nanomaterials for their application in energy storage and conversion fields. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Tracing nanoparticles and photosensitizing molecules at transmission electron microscopy by diaminobenzidine photo-oxidation.

PubMed

Malatesta, M; Pellicciari, C; Cisterna, B; Costanzo, M; Galimberti, V; Biggiogera, M; Zancanaro, C

2014-04-01

During the last three decades, diaminobenzidine photo-oxidation has been applied in a variety of studies to correlate light and electron microscopy. Actually, when a fluorophore is excited by light, it can induce the oxidation of diaminobenzidine into an electron-dense osmiophilic product, which precipitates in close proximity to the fluorophore, thereby allowing its ultrastructural detection. This method has very recently been developed for two innovative applications: tracking the fate of fluorescently labeled nanoparticles in single cells, and detecting the subcellular location of photo-active molecules suitable for photodynamic therapy. These studies established that the cytochemical procedures exploiting diaminobenzidine photo-oxidation represent a reliable tool for detecting, inside the cells, with high sensitivity fluorescing molecules. These procedures are trustworthy even if the fluorescing molecules are present in very low amounts, either inside membrane-bounded organelles, or at the surface of the plasma membrane, or free in the cytosol. In particular, diaminobenzidine photo-oxidation allowed elucidating the mechanisms responsible for nanoparticles internalization in neuronal cells and for their escape from lysosomal degradation. As for the photo-active molecules, their subcellular distribution at the ultrastructural level provided direct evidence for the lethal multiorganelle photo-damage occurring after cell photo-sensitization. In addition, DAB photo-oxidized samples are suitable for the ultrastructural detection of organelle-specific molecules by post-embedding gold immunolabeling. Copyright © 2013 Elsevier Ltd. All rights reserved.

Effect of spatial confinement on magnetic hyperthermia via dipolar interactions in Fe3O4 nanoparticles for biomedical applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sadat, M E; Patel, Ronak; Sookoor, Jason

2014-09-01

In this work, the effect of nanoparticle confinement on the magnetic relaxation of iron oxide (Fe3O4) nanoparticles (NP) was investigated by measuring the hyperthermia heating behavior in high frequency alternating magnetic field. Three different Fe3O4 nanoparticle systems having distinct nanoparticle configurations were studied in terms of magnetic hyperthermia heating rate and DC magnetization. All magnetic nanoparticle (MNP) systems were constructed using equivalent ~10nm diameter NP that were structured differently in terms of configuration, physical confinement, and interparticle spacing. The spatial confinement was achieved by embedding the Fe3O4 nanoparticles in the matrices of the polystyrene spheres of 100 nm, while themore » unconfined was the free Fe3O4 nanoparticles well-dispersed in the liquid via PAA surface coating. Assuming the identical core MNPs in each system, the heating behavior was analyzed in terms of particle freedom (or confinement), interparticle spacing, and magnetic coupling (or dipole-dipole interaction). DC magnetization data were correlated to the heating behavior with different material properties. Analysis of DC magnetization measurements showed deviation from classical Langevin behavior near saturation due to dipole interaction modification of the MNPs resulting in a high magnetic anisotropy. It was found that the Specific Absorption Rate (SAR) of the unconfined nanoparticle systems were significantly higher than those of confined (the MNPs embedded in the polystyrene matrix). This increase of SAR was found to be attributable to high Néel relaxation rate and hysteresis loss of the unconfined MNPs. It was also found that the dipole-dipole interactions can significantly reduce the global magnetic response of the MNPs and thereby decrease the SAR of the nanoparticle systems.« less

NMR-based metabonomic analysis of MnO-embedded iron oxide nanoparticles as potential dual-modal contrast agents

NASA Astrophysics Data System (ADS)

Li, Jinquan; Zhou, Zijian; Feng, Jianghua; Cai, Shuhui; Gao, Jinhao; Chen, Zhong

2014-05-01

MnO-embedded iron oxide nanoparticles (MnIO-NPs) can be treated as potential dual-modal contrast agents. However, their overall bio-effects and potential toxicity remain unknown. In this study, the metabolic effects of MnIO-NPs (dosed at 1 and 5 mg Fe/kg) on Sprague-Dawley rats were investigated using metabonomic analysis, histopathological examination, and conventional biochemical analysis. The histological changes included a focal inflammation in the liver at high-dose and a slightly enlarged area of splenic white pulp after 48 h post-dose. Blood biochemical analysis showed that albumin, globulins, aspartate aminotransferase, lactate dehydrogenase, blood urea nitrogen, and glucose changed distinctly compared to the control. The metabonomic analysis of body fluids (serum and urine) and tissues (liver, kidney, and spleen) indicated that MnIO-NPs induced metabolic perturbation in rats including energy, nucleotides, amino acids and phospholipid metabolisms. Besides, the variations of supportive nutrients: valine, leucine, isoleucine, nicotinamide adenine dinucleotide (phosphate), and nicotinamide, and the conjugation substrates: glycine, taurine, glutamine, glutathione, and methyl donors (formate, sarcosine, dimethylglycine, choline, and betaine) were involved in detoxification reaction of MnIO-NPs. The obtained information would provide identifiable ground for the candidate selection and optimization.

Toward deep blue nano hope diamonds: heavily boron-doped diamond nanoparticles.

PubMed

Heyer, Steffen; Janssen, Wiebke; Turner, Stuart; Lu, Ying-Gang; Yeap, Weng Siang; Verbeeck, Jo; Haenen, Ken; Krueger, Anke

2014-06-24

The production of boron-doped diamond nanoparticles enables the application of this material for a broad range of fields, such as electrochemistry, thermal management, and fundamental superconductivity research. Here we present the production of highly boron-doped diamond nanoparticles using boron-doped CVD diamond films as a starting material. In a multistep milling process followed by purification and surface oxidation we obtained diamond nanoparticles of 10-60 nm with a boron content of approximately 2.3 × 10(21) cm(-3). Aberration-corrected HRTEM reveals the presence of defects within individual diamond grains, as well as a very thin nondiamond carbon layer at the particle surface. The boron K-edge electron energy-loss near-edge fine structure demonstrates that the B atoms are tetrahedrally embedded into the diamond lattice. The boron-doped diamond nanoparticles have been used to nucleate growth of a boron-doped diamond film by CVD that does not contain an insulating seeding layer.

Plasmonic properties of Ag nanoparticles embedded in GeO2-SiO2 matrix by atom beam sputtering.

PubMed

Mohapatra, Satyabrata

2016-02-07

Nanocomposite thin films containing Ag nanoparticles embedded in the GeO2-SiO2 matrix were synthesized by the atom beam co-sputtering technique. The structural, optical and plasmonic properties and the chemical composition of the nanocomposite thin films were studied by transmission electron microscopy (TEM) with energy dispersive X-ray spectroscopy (EDX), UV-visible absorption spectroscopy and X-ray photoelectron spectroscopy (XPS). UV-visible absorption studies on Ag-SiO2 nanocomposites revealed the presence of a strong localized surface plasmon resonance (LSPR) peak characteristic of Ag nanoparticles at 413 nm, which showed a blue shift of 26 nm (413 to 387 nm) along with a significant broadening and drastic decrease in intensity with the incorporation of 16 at% of Ge into the SiO2 matrix. TEM studies on Ag-GeO2-SiO2 nanocomposite thin films confirmed the presence of Ag nanoparticles with an average size of 3.8 nm in addition to their aggregates with an average size of 16.2 nm. Thermal annealing in air resulted in strong enhancement in the intensity of the LSPR peak, which showed a regular red shift of 51 nm (from 387 to 438 nm) with the increase in annealing temperature up to 500 °C. XPS studies showed that annealing in air resulted in oxidation of excess Ge atoms in the nanocomposite into GeO2. Our work demonstrates the possibility of controllably tuning the LSPR of Ag nanoparticles embedded in the GeO2-SiO2 matrix by single-step thermal annealing, which is interesting for optical applications.

Negative capacitance in (FeCoZr)-(PZT) nanocomposite films

NASA Astrophysics Data System (ADS)

Kołtunowicz, T. N.; Fedotova, J. A.; Zhukowski, P.; Saad, A.; Fedotov, A.; Kasiuk, J. V.; Larkin, A. V.

2013-03-01

In this work, attention was focused on the inductive contribution to the real part of admittance G(T, f) in (Fe0.45Co0.45Zr0.10)x(PZT)(1-x) nanocomposite films deposited in a mixed argon-oxygen atmosphere. The observed G(x, f, T) dependences for the films on the dielectric side of the insulator-metal transition demonstrated the negative capacitance (NC) effect that was maximal for the nanocomposites with 0.40 < x < 0.60, where the metallic FeCoZr nanoparticles were totally oxidized. The NC effect was explained by a specially developed model for the ac hopping conductance of the electrons between the fully oxidized nanoparticles embedded in the PZT matrix. In accordance with the model, under the determined conditions the observed structure of nanocomposites led to an increase in the hopping electron mean lifetime on nanoparticles and hence to the possibility of positive angles of the phase shifts θ and a proper NC (inductive-like contribution) effect.

Comprehensive investigation of core-shell dimer nanoparticles size, distance and thicknesses on performance of a hybrid organic-inorganic halide perovskite solar cell

NASA Astrophysics Data System (ADS)

Heidarzadeh, Hamid

2018-03-01

Significant performance enhancement in an ultrathin perovskite (CH3NH3PbI3) solar cell is done using plasmonic embedded core–shell dimer nanoparticles. Three-dimensional finite difference time-domain (FDTD) method is used. A perovskite absorber with a volume of 400 × 400 × 200 nm3 is considered. At first, a cell with one embedded nanoparticle is simulated. Absorptance of CH3NH3PbI3 absorber and gold nanoparticle are obtained. An optimization is done. Then a cell with embedded dimer nanoparticles is evaluated. The results show higher photocurrent enhancement for that in compared to a cell with one embedded nanoparticle. To further photocurrent enhancement, gold-SiO2 core–shell nanoparticles are used. Photocurrents of 23.37 mA cm‑2, 23.3 mA cm‑2, 22.5 mA cm‑2 and 21.47 mA cm‑2 are obtained for a cell with two embedded core–shell nanoparticles with core radius of 60 nm and shell thickness of 2 nm, 5 nm, 10 nm and 20 nm, respectively. It is important to mention that the photocurrent is 17.9 mA cm‑2 for reference cell and 19.8 mA cm‑2 for a cell with one embedded nanoparticle. Higher photocurrent is due to the near-field plasmonic effect.

Formation and Stability of Pb-Sn Embedded Multiphase Alloy Nanoparticles via Mechanical Alloying

NASA Astrophysics Data System (ADS)

Khan, Patan Yousaf; Devi, M. Manolata; Biswas, Krishanu

2015-08-01

The present paper describes the preparation, characterization, and stability of Pb-Sn multiphase alloy nanoparticles embedded in Al matrix via mechanical alloying (MA). MA is a solid-state processing route, which can produce nanocrystalline phases by severely deforming the materials at high strain rate. Therefore, in order to understand the effect of the increasing interface as well as defects on the phase transformation behavior of Pb-Sn nanoparticles, Pb-Sn multiphase nanoparticles have been embedded in Al by MA. The nanoparticles have extensively been characterized using X-ray diffraction and transmission electron microscope. The characterization reveals the formation of biphasic as well as single-phase solid solution nanoparticles embedded in the matrix. The detailed microstructural and differential scanning calorimetry studies indicate that the formation of biphasic nanoparticles is due to size effect, mechanical attrition, and ballistic diffusion of Pb and Sn nanoparticles embedded in Al grains. Thermal characterization data reveal that the heating event consists of the melting peaks due to the multiphase nanoparticles and the peak positions shift to lower temperature with the increase in milling time. The role of interface structure is believed to play a prominent role in determining the phase stability of the nanoparticle. The results are discussed in the light of the existing literature.

High catalytic activity of oriented 2.0.0 copper(I) oxide grown on graphene film

PubMed Central

Primo, Ana; Esteve-Adell, Ivan; Blandez, Juan F.; Dhakshinamoorthy, Amarajothi; Álvaro, Mercedes; Candu, Natalia; Coman, Simona M.; Parvulescu, Vasile I.; García, Hermenegildo

2015-01-01

Metal oxide nanoparticles supported on graphene exhibit high catalytic activity for oxidation, reduction and coupling reactions. Here we show that pyrolysis at 900 °C under inert atmosphere of copper(II) nitrate embedded in chitosan films affords 1.1.1 facet-oriented copper nanoplatelets supported on few-layered graphene. Oriented (1.1.1) copper nanoplatelets on graphene undergo spontaneous oxidation to render oriented (2.0.0) copper(I) oxide nanoplatelets on few-layered graphene. These films containing oriented copper(I) oxide exhibit as catalyst turnover numbers that can be three orders of magnitude higher for the Ullmann-type coupling, dehydrogenative coupling of dimethylphenylsilane with n-butanol and C–N cross-coupling than those of analogous unoriented graphene-supported copper(I) oxide nanoplatelets. PMID:26509224

Magneto-photo-acoustic imaging

PubMed Central

Qu, Min; Mallidi, Srivalleesha; Mehrmohammadi, Mohammad; Truby, Ryan; Homan, Kimberly; Joshi, Pratixa; Chen, Yun-Sheng; Sokolov, Konstantin; Emelianov, Stanislav

2011-01-01

Magneto-photo-acoustic imaging, a technique based on the synergy of magneto-motive ultrasound, photoacoustic and ultrasound imaging, is introduced. Hybrid nanoconstructs, liposomes encapsulating gold nanorods and iron oxide nanoparticles, were used as a dual-contrast agent for magneto-photo-acoustic imaging. Tissue-mimicking phantom and macrophage cells embedded in ex vivo porcine tissue were used to demonstrate that magneto-photo-acoustic imaging is capable of visualizing the location of cells or tissues labeled with dual-contrast nanoparticles with sufficient contrast, excellent contrast resolution and high spatial resolution in the context of the anatomical structure of the surrounding tissues. Therefore, magneto-photo-acoustic imaging is capable of identifying the nanoparticle-labeled pathological regions from the normal tissue, providing a promising platform to noninvasively diagnose and characterize pathologies. PMID:21339883

Europium-engineered iron oxide nanocubes with high T1 and T2 contrast abilities for MRI in living subjects

NASA Astrophysics Data System (ADS)

Yang, Lijiao; Zhou, Zijian; Liu, Hanyu; Wu, Changqiang; Zhang, Hui; Huang, Guoming; Ai, Hua; Gao, Jinhao

2015-04-01

Magnetic resonance imaging (MRI) contrast agents with both positive (T1) and negative (T2) contrast abilities are needed in clinical diagnosis for fault-free accurate detection of lesions. We report a facile synthesis of europium-engineered iron oxide (EuIO) nanocubes as T1 and T2 contrast agents for MRI in living subjects. The Eu(iii) oxide-embedded iron oxide nanoparticles significantly increase the T1 relaxivity with an enhanced positive contrast effect. EuIO nanocubes with 14 nm in diameter showed a high r1 value of 36.8 mM-1 s-1 with respect to total metal ions (Fe + Eu), which is about 3 times higher than that of Fe3O4 nanoparticles with similar size. Moreover, both r1 and r2 values of EuIO nanocubes can be tuned by varying their sizes and Eu doping ratios. After citrate coating, EuIO nanocubes can provide enhanced T1 and T2 contrast effects in small animals, particularly in the cardiac and liver regions. This work may provide an insightful strategy to design MRI contrast agents with both positive and negative contrast abilities for biomedical applications.Magnetic resonance imaging (MRI) contrast agents with both positive (T1) and negative (T2) contrast abilities are needed in clinical diagnosis for fault-free accurate detection of lesions. We report a facile synthesis of europium-engineered iron oxide (EuIO) nanocubes as T1 and T2 contrast agents for MRI in living subjects. The Eu(iii) oxide-embedded iron oxide nanoparticles significantly increase the T1 relaxivity with an enhanced positive contrast effect. EuIO nanocubes with 14 nm in diameter showed a high r1 value of 36.8 mM-1 s-1 with respect to total metal ions (Fe + Eu), which is about 3 times higher than that of Fe3O4 nanoparticles with similar size. Moreover, both r1 and r2 values of EuIO nanocubes can be tuned by varying their sizes and Eu doping ratios. After citrate coating, EuIO nanocubes can provide enhanced T1 and T2 contrast effects in small animals, particularly in the cardiac and liver regions. This work may provide an insightful strategy to design MRI contrast agents with both positive and negative contrast abilities for biomedical applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr00774g

Development of electrospun nanofiber composites for pointof-use water treatment

NASA Astrophysics Data System (ADS)

Peter, Katherine T.

A range of chemical pollutants now contaminate drinking water sources and present a public health concern, including organic compounds, such as pharmaceuticals and pesticides, and both metalloids and heavy metals, such as arsenic and lead. Metalloids and heavy metals have been detected in private drinking water wells, which do not fall under federal drinking water regulations, as well as in urban tap water, due to the introduction of contamination to the drinking water distribution system. Further, many so-called "emerging organic contaminants," which are present in drinking water sources at detectable levels but have unknown long-term health implications, do not fall under federal drinking water regulations. To protect the health of consumers, drinking water treatment at the point-of-use (POU) (i.e., the tap) is essential. Next-generation POU treatment technologies must require minimal energy inputs, be simple enough to permit broad application among different users, and be easily adaptable for removal of a wide range of pollutants. Nanomaterials, such as carbon nanotubes and iron oxide nanoparticles, are ideal candidates for next-generation drinking water treatment, as they exhibit unique, high reactivity and necessitate small treatment units. However, concerns regarding water pressure requirements and nanomaterial release into the treated supply limit their application in traditional reactor designs. To bridge the gap between potential and practical application of nanomaterials, this study utilizes electrospinning to fabricate composite nanofiber filters that effectively deploy nanomaterials in drinking water treatment. In electrospinning, a high voltage draws a polymer precursor solution (which can contain nanomaterial additives, in the case of nanocomposites) from a needle to deposit a non-woven nanofiber filter on a collector surface. Using electrospinning, we develop an optimized, macroporous carbon nanotube-carbon nanofiber composite that utilizes the sorption capacity of embedded carbon nanotubes, and achieves a key balance between material strength and reactivity towards organic pollutants. Additionally, via single-pot syntheses, we develop two optimized polymer-iron oxide composites for removal of heavy metal contamination by inclusion of iron oxide nanoparticles and either cationic or anionic surfactants in the electrospinning precursor solution. In hybrid materials that contain a well-retained quaternary ammonium surfactant (tetrabutylammonium bromide) and iron oxide nanoparticles, ion exchange sites and iron oxide sites are selective for chromate and arsenate removal, respectively. We demonstrated that a sulfonate surfactant, sodium dodecyl sulfate, acted as a removable porogen and an agent for surface segregation of iron oxide nanoparticles, thus enhancing composite performance for removal of lead, copper, and cadmium. Notably, nanoparticles embedded in composites exhibited comparable activity to freely dispersed nanoparticles. Collectively, the composites developed in this work represent a substantial advance towards the overlap of effective nanomaterial immobilization and utilization of nanomaterial reactivity. Outcomes of this work advance current knowledge of nanocomposite fabrication, and contribute to the responsible and effective deployment of nanomaterials in POU drinking water treatment.

Photocatalytic Applications of Electrospun TiO2 Nanofibres Embedded with Bimodal Sized and Prismatic Gold Nanoparticles.

PubMed

Gopika, G; Asha, A M; Sivakumar, N; Balakrishnan, A; Nair, S V; Subramanian, K R V

2015-09-01

In this paper, we have synthesized electrospun TiO2 nanofibers embedded with bimodal sized and prismatic gold nanoparticles. The surface plasmons generated in the gold nanoparticles were used to enhance the performance of photocatalysis. The photocatalytic conversion efficiencies of these bimodal sized/prismatic gold nanoparticles when embedded in electrospun TiO2 fibres showed an enhancement of upto 60% over bare fiber systems and also show higher efficiencies than electrospun fibrous systems embedded with unimodal sized gold nanoparticles. Anisotropic bimodal gold nanoparticles show the highest degree of photocatalytic activity. This may be attributed to greater density/concentration of nanoparticles with higher effective surface area and formation of a junction between the smaller and larger nanoparticles. Such a bimodally distributed range of nanoparticles could also lead to greater trapping of charge carriers at the TiO2 conduction band edge and promoting catalytic reactions on account of these trapped charges. This enhanced photocatalytic activity is explained by invoking different operating mechanisms such as improved surface area, greater trapping, coarse plasmon resonance and band effects. Thus, a useful applicability of the gold nanoparticles is shown in the area of photocatalysis.

Controllable Self-Assembly of Micro-Nanostructured Si-Embedded Graphite/Graphene Composite Anode for High-Performance Li-Ion Batteries.

PubMed

Lin, Ning; Xu, Tianjun; Li, Tieqiang; Han, Ying; Qian, Yitai

2017-11-15

Si-containing graphite-based composites are considered as promising high-capacity anodes for lithium-ion batteries (LIBs). Here, a controllable and scalable self-assembly strategy is developed to produce micro-nanostructured graphite/Si/reduced graphene oxides composite (SGG). The self-assembly procedure is realized by the hydrogen bond interaction between acylamino-modified graphite and graphene oxides (GO); Si nanoparticles are in situ embedded between graphite and GO sheets uniformly. This architecture is able to overcome the incompatibility between Si nanoparticles and microsized graphite. Accordingly, the as-prepared SGG anode (Si 8 wt %) delivers a reversible Li-storage capacity of 572 mAh g -1 at 0.2 C, 502.2 mAh g -1 after 600 cycles at 0.8 C with a retention of 92%, and a capacity retention of 64% even at 10 C. The impressive electrochemical properties are ascribed to the stable architecture and three-dimensional conductive network constructed by graphite and graphene sheets, which can accommodate the huge volume change of Si, keep the conductive contact and structural integrity, and suppress side reactions with electrolyte. Additionally, the full-cell (LiFePO 4 cathode/SGG anode) delivers a specific capacity of 550 mAh g -1 with a working potential beyond 3.0 V.

Core-Shell ZIF-8@ZIF-67-Derived CoP Nanoparticle-Embedded N-Doped Carbon Nanotube Hollow Polyhedron for Efficient Overall Water Splitting.

PubMed

Pan, Yuan; Sun, Kaian; Liu, Shoujie; Cao, Xing; Wu, Konglin; Cheong, Weng-Chon; Chen, Zheng; Wang, Yu; Li, Yang; Liu, Yunqi; Wang, Dingsheng; Peng, Qing; Chen, Chen; Li, Yadong

2018-02-21

The construction of highly active and stable non-noble-metal electrocatalysts for hydrogen and oxygen evolution reactions is a major challenge for overall water splitting. Herein, we report a novel hybrid nanostructure with CoP nanoparticles (NPs) embedded in a N-doped carbon nanotube hollow polyhedron (NCNHP) through a pyrolysis-oxidation-phosphidation strategy derived from core-shell ZIF-8@ZIF-67. Benefiting from the synergistic effects between highly active CoP NPs and NCNHP, the CoP/NCNHP hybrid exhibited outstanding bifunctional electrocatalytic performances. When the CoP/NCNHP was employed as both the anode and cathode for overall water splitting, a potential as low as 1.64 V was needed to achieve the current density of 10 mA·cm -2 , and it still exhibited superior activity after continuously working for 36 h with nearly negligible decay in potential. Density functional theory calculations indicated that the electron transfer from NCNHP to CoP could increase the electronic states of the Co d-orbital around the Fermi level, which could increase the binding strength with H and therefore improve the electrocatalytic performance. The strong stability is attributed to high oxidation resistance of the CoP surface protected by the NCNHP.

Novel DiR and SPIO nanoparticles embedded PEG-PLGA nanobubbles as a multimodalimaging contrast agent.

PubMed

Luo, Binhua; Zhang, Huajie; Liu, Xuhan; Rao, Rong; Wu, Yun; Liu, Wei

2015-01-01

Fluorescence dye DiR and superparamagnetic iron oxide nanoparticles (SPIONs) embedded in PEG-PLGA nanobubbles (DiR-SPIO-NBs) were produced using double emulsion method on a membrane of Shirasu porous glass (SPG). The nanobubbles encapsulated with DiR and SPIONs had a liquid core (perfluoropentane) and a PEG-PLGA shell. DiR-SPIO-NBs showed biocompatibility based on MTT cytotoxicity and hemolysis studies. The PFP encapsulated in the nanobubbles experienced phase transition under ultrasonic irradation. Nanobubbles dispersed well in saline over 3 months, and the relaxivity was 127.9 mM(-1)s(-1), suggesting that it could be used as a contrast agent in MRI. The MR and fluorescence images in vivo demonstrated that the signal intensity in the spleen and liver was significantly enhanced with the treatment of nanobubbles. In addition, results of ultrasound images suggested that the nanobubbles had persistent contrast ability. In conclusion, nanobubbles could be utilized as an US/MRI/fluorescence contrast agent.

Starch nanoparticle as a vitamin E-TPGS carrier loaded in silk fibroin-poly(vinyl alcohol)-Aloe vera nanofibrous dressing.

PubMed

Kheradvar, Shadi Alsadat; Nourmohammadi, Jhamak; Tabesh, Hadi; Bagheri, Behnam

2018-06-01

Core-sheath nanofibrous mat as a new vitamin E (VE) delivery system based on silk fibroin (SF)/poly(vinyl alcohol) (PVA)/aloe vera (AV) was successfully prepared by the electrospinning method. Initially, VE-loaded starch nanoparticles were produced and then incorporated into the best beadless SF-PVA-AV nanofibers. The successful loading of VE in starch nanoparticles was proved by Fourier-transform infrared spectroscopy. The scanning electron microscopy and transmission electron microscopy indicated that spherical nanoparticles were successfully embedded within the nanofibers. In vitro release studies demonstrated that the release of VE was controlled by Fickian diffusion and was faster in samples containing more nanoparticles. Fibroblast attachment, proliferation, and collagen secretion were enhanced after adding AV and VE to the SF-PVA nanomatrix. Moreover, the incorporation of VE into the nanocomposite dressing enhanced antioxidant activity, which can have a positive effect on wound healing process by protecting the cells from toxic oxidation products. Copyright © 2018 Elsevier B.V. All rights reserved.

Enhanced antibacterial nanocomposite mats by coaxial electrospinning of polycaprolactone fibers loaded with Zn-based nanoparticles.

PubMed

Prado-Prone, Gina; Silva-Bermudez, Phaedra; Almaguer-Flores, Argelia; García-Macedo, Jorge A; García, Victor I; Rodil, Sandra E; Ibarra, Clemente; Velasquillo, Cristina

2018-04-16

ZnO and Zn acetate nanoparticles were embedded in polycaprolactone coaxial-fibers and uniaxial-fibers matrices to develop potential antibacterial nanocomposite wound dressings (mats). Morphology, composition, wettability, crystallinity and fiber structure of mats were characterized. Antibacterial properties of mats were tested against E. coli and S. aureus by turbidity and MTT assays. The effect of UVA illumination (prior to bacteria inoculation) on mats' antibacterial activity was also studied. Results showed that a coaxial-fibers design maintained nanoparticles distributed in the outer-shell of fibers and, in general, enhanced the antibacterial effect of the mats, in comparison to conventional uniaxial-fibers mats. Results indicated that mats simultaneously inhibited planktonic and biofilm bacterial growth by, probably, two main antibacterial mechanisms; 1) release of Zn 2+ ions (mainly from Zn acetate nanoparticles) and 2) photocatalytic oxidative processes exerted by ZnO nanoparticles. Antibacterial properties of mats were significantly improved by coaxial-fibers design and exposure to UVA-light prior to bacteria inoculation. Copyright © 2018 Elsevier Inc. All rights reserved.

Drug release from nanoparticles embedded in four different nanofibrillar cellulose aerogels.

PubMed

Valo, Hanna; Arola, Suvi; Laaksonen, Päivi; Torkkeli, Mika; Peltonen, Leena; Linder, Markus B; Serimaa, Ritva; Kuga, Shigenori; Hirvonen, Jouni; Laaksonen, Timo

2013-09-27

Highly porous nanocellulose aerogels prepared by freeze-drying from various nanofibrillar cellulose (NFC) hydrogels are introduced as nanoparticle reservoirs for oral drug delivery systems. Here we show that beclomethasone dipropionate (BDP) nanoparticles coated with amphiphilic hydrophobin proteins can be well integrated into the NFC aerogels. NFCs from four different origins are introduced and compared to microcrystalline cellulose (MCC). The nanocellulose aerogel scaffolds made from red pepper (RC) and MCC release the drug immediately, while bacterial cellulose (BC), quince seed (QC) and TEMPO-oxidized birch cellulose-based (TC) aerogels show sustained drug release. Since the release of the drug is controlled by the structure and interactions between the nanoparticles and the cellulose matrix, modulation of the matrix formers enable a control of the drug release rate. These nanocomposite structures can be very useful in many pharmaceutical nanoparticle applications and open up new possibilities as carriers for controlled drug delivery. Copyright © 2013 Elsevier B.V. All rights reserved.

Triple-wavelength passively Q-switched ytterbium-doped fibre laser using zinc oxide nanoparticles film as a saturable absorber

NASA Astrophysics Data System (ADS)

Mohsin Al-Hayali, Sarah Kadhim; Hadi Al-Janabi, Abdul

2018-07-01

We report on the generation of a triple-wavelength passively Q-switched ytterbium-doped fibre laser using a saturable absorber (SA) based on zinc oxide nanoparticles (ZnO NPs) film. The SA was fabricated by embedding ZnO NPs powder into a polyvinyl alcohol as a host polymer. By properly adjusting the pump power and the polarization state, single-, dual- and triple-wavelength Q-switching are stably generated without additional components (such as optical filter, or fibre grating). For the triple wavelength operation, the fibre laser generates a maximum pulse repetition of 87.9 kHz with the shortest pulse duration of 2.7 μs. To the best of authors' knowledge, it's the first demonstration of triple-wavelength passively Q-switching fibre laser using ZnO NPs as a SA. Our results suggest that ZnO is a promising SA for multi-wavelength laser operation.

Energetic electron processes fluorescence effects for structured nanoparticles X-ray analysis and nuclear medicine applications

NASA Astrophysics Data System (ADS)

Taborda, A.; Desbrée, A.; Carvalho, A.; Chaves, P. C.; Reis, M. A.

2016-08-01

Superparamagnetic iron oxide (SPIO) nanoparticles are widely used as contrast agents for nuclear magnetic resonance imaging (MRI), and can be modified for improved imaging or to become tissue-specific or even protein-specific. The knowledge of their detailed elemental composition characterisation and potential use in nuclear medicine applications, is, therefore, an important issue. X-ray fluorescence techniques such as particle induced X-ray emission (PIXE) or X-ray fluorescence spectrometry (XRF), can be used for elemental characterisation even in problematic situations where very little sample volume is available. Still, the fluorescence coefficient of Fe is such that, during the decay of the inner-shell ionised atomic structure, keV Auger electrons are produced in excess to X-rays. Since cross-sections for ionisation induced by keV electrons, for low atomic number atoms, are of the order of 103 barn, care should be taken to account for possible fluorescence effects caused by Auger electrons, which may lead to the wrong quantification of elements having atomic number lower than the atomic number of Fe. Furthermore, the same electron processes will occur in iron oxide nanoparticles containing 57Co, which may be used for nuclear medicine therapy purposes. In the present work, simple approximation algorithms are proposed for the quantitative description of radiative and non-radiative processes associated with Auger electrons cascades. The effects on analytical processes and nuclear medicine applications are quantified for the case of iron oxide nanoparticles, by calculating both electron fluorescence emissions and energy deposition on cell tissues where the nanoparticles may be embedded.

High-yield aqueous synthesis of multi-branched iron oxide core-gold shell nanoparticles: SERS substrate for immobilization and magnetic separation of bacteria

NASA Astrophysics Data System (ADS)

Tamer, Ugur; Onay, Aykut; Ciftci, Hakan; Bozkurt, Akif Göktuğ; Cetin, Demet; Suludere, Zekiye; Hakkı Boyacı, İsmail; Daniel, Philippe; Lagarde, Fabienne; Yaacoub, Nader; Greneche, Jean-Marc

2014-10-01

The high product yield of multi-branched core-shell Fe3- x O4@Au magnetic nanoparticles was synthesized used as magnetic separation platform and surface-enhanced Raman scattering (SERS) substrates. The multi-branched magnetic nanoparticles were prepared by a seed-mediated growth approach using magnetic gold nanospheres as the seeds and subsequent reduction of metal salt with ascorbic acid in the presence of a stabilizing agent chitosan biopolymer and silver ions. The anisotropic growth of nanoparticles was observed in the presence of chitosan polymer matrix resulting in multi-branched nanoparticles with a diameter over 100 nm, and silver ions also play a crucial role on the growth of multi-branched nanoparticles. We propose the mechanism of the formation of multi-branched nanoparticles while the properties of nanoparticles embedded in chitosan matrix are discussed. The surface morphology of nanoparticles was characterized with transmission electron microscopy, scanning electron microscopy, ultraviolet visible spectroscopy (UV-Vis), X-ray diffraction, and fourier transform infrared spectroscopy and 57Fe Mössbauer spectrometry. Additionally, the magnetic properties of the nanoparticles were also examined. We also demonstrated that the synthesized Fe3- x O4@Au multi-branched nanoparticle is capable of targeted separation of pathogens from matrix and sensing as SERS substrates.

Ni nanoparticles decorated onto graphene oxide with SiO2 as interlayer for high performance on histidine-rich protein separation

NASA Astrophysics Data System (ADS)

Yang, Xiaodan; Zhang, Min; Zheng, Jing; Li, Weizhen; Gan, Wenjun; Xu, Jingli; Hayat, Tasawar; Alharbi, Njud S.; Yang, Fan

2018-05-01

Sandwich-like structure of graphene oxide (GO) @SiO2@C-Ni nanosheets were prepared by combining an extended stöber method with subsequent carbonization treatment, in which polydopamine was used as reducing agent and carbon source. Firstly, the GO nanosheets were covered with SiO2 interlayer and finally coated with a outer shell of nickel ion doped polydopamine (PDA-Ni2+) with an extended stöber method. Followed by a carbonization to produce the GO@SiO2@C-Ni sheets with metallic nickel nanoparticles embedded in PDA-derived thin graphic carbon layer. Notably, silica interlayer played a vital role in the formation of such GO@SiO2@C-Ni sheets. Without the protection of SiO2, the hydrophobic graphene@C-Ni composites were obtained instead. While with silica layer as the spacer, the obtained hydrophilic GO@SiO2@C-Ni composites were not only well dispersed in the solution, but also can be adjusted in terms of the size and density of Ni nanoparticles (NPs) on surface by changing the calcination temperature or the molar ratio between dopamine and nickel salt. Furthermore, nickel nanoparticles decorated on GO@SiO2 sheets were employed to enrich His-rich proteins (BHb and BSA) via specific metal affinity force between polyhistidine groups and nickel nanoparticles.

Synthesis of embedded titanium dioxide nanoparticles by oxygen ion implantation in titanium films

NASA Astrophysics Data System (ADS)

Rukade, Deepti. A.; Desai, C. A.; Kulkarni, Nilesh; Tribedi, L. C.; Bhattacharyya, Varsha

2013-02-01

Thin films of titanium of 100nm thickness are deposited on fused silica substrates. These films are implanted by oxygen ions with implantation energy of 60keV obtained from ECR based highly charged ion accelerator. The implanted films are later annealed in a tube furnace to establish nanophase formation. The post implanted annealed films are characterized by UV-Visible Spectroscopy and Glancing Angle X-ray Diffraction technique (GAXRD). The phase formed and particle size is determined by GAXRD. Nanoparticle formation is confirmed by the UV-VIS spectroscopic analysis that shows quantum size effects in the form of a blue shift in the band-gap energy of titanium-oxide.

Size dependent nonlinear optical properties of spin coated zinc oxide-polystyrene nanocomposite films

NASA Astrophysics Data System (ADS)

Jeeju, Pullarkat P.; Jayalekshmi, S.; Chandrasekharan, K.; Sudheesh, P.

2012-11-01

Using simple wet chemical method at room temperature, zinc oxide (ZnO) nanoparticles embedded in polystyrene (PS) matrix were synthesized. The size of the ZnO nanoparticles could be varied by varying the precursor concentration, reaction time and stirring speed. Transparent films of ZnO/PS nanocomposites of thickness around 1 μm were coated on ultrasonically cleaned glass substrates by spin coating. The optical absorptive nonlinearity in ZnO/PS nanocomposite films was investigated using open aperture Z-scan technique with nanosecond laser pulses at 532 nm. The results indicate optical limiting type nonlinearity in the films due to two-photon absorption in ZnO. These films also show a self-defocusing type negative nonlinear refraction in closed aperture Z-scan experiment. The observed nonlinear absorption is strongly dependent on particle size and the normalized transmittance could be reduced to as low as 0.43 by the suitable choice of the ZnO nanoparticle size. These composite films can hence be used as efficient optical limiters for sensor protection. The much-pronounced nonlinear response of these composite films, compared to pure ZnO, combined with the improved stability of ZnO nanoparticles in the PS matrix offer prospects of application of these composite films in the fabrication of stable non-linear optical devices.

Ultra-high sensitive substrates for surface enhanced Raman scattering, made of 3 nm gold nanoparticles embedded on SiO2 nanospheres

NASA Astrophysics Data System (ADS)

Phatangare, A. B.; Dhole, S. D.; Dahiwale, S. S.; Bhoraskar, V. N.

2018-05-01

The surface properties of substrates made of 3 nm gold nanoparticles embedded on SiO2 nanospheres enabled fingerprint detection of thiabendazole (TBZ), crystal violet (CV) and 4-Aminothiophenol (4-ATP) at an ultralow concentration of ∼10-18 M by surface enhanced Raman spectroscopy (SERS). Gold nanoparticles of an average size of ∼3 nm were synthesized and simultaneously embedded on SiO2 nanospheres by the electron irradiation method. The substrates made from the 3 nm gold nanoparticles embedded on SiO2 nanospheres were successfully used for recording fingerprint SERS spectra of TBZ, CV and 4-ATP over a wide range of concentrations from 10-6 M to 10-18 M using 785 nm laser. The unique features of these substrates are roughness near the surface due to the inherent structural defects of 3 nm gold nanoparticles, nanogaps of ≤ 1 nm between the embedded nanoparticles and their high number. These produced an abundance of nanocavities which act as active centers of hot-spots and provided a high electric field at the reporter molecules and thus an enhancement factor required to record the SERS spectra at ultra low concentration of 10-18 M. The SERS spectra recorded by the substrates of 4 nm and 6 nm gold nanoparticles are discussed.

Surface plasmon-enhanced light-emitting diodes using silver nanoparticles embedded in p-GaN.

PubMed

Cho, Chu-Young; Kwon, Min-Ki; Lee, Sang-Jun; Han, Sang-Heon; Kang, Jang-Won; Kang, Se-Eun; Lee, Dong-Yul; Park, Seong-Ju

2010-05-21

We demonstrate the surface plasmon-enhanced blue light-emitting diodes (LEDs) using Ag nanoparticles embedded in p-GaN. A large increase in optical output power of 38% is achieved at an injection current of 20 mA due to an improved internal quantum efficiency of the LEDs. The enhancement of optical output power is dependent on the density of the Ag nanoparticles. This improvement can be attributed to an increase in the spontaneous emission rate through resonance coupling between the excitons in multiple quantum wells and localized surface plasmons in Ag nanoparticles embedded in p-GaN.

Disintegration of nano-embedded microparticles after deposition on mucus: A mechanistic study.

PubMed

Ruge, Christian A; Bohr, Adam; Beck-Broichsitter, Moritz; Nicolas, Valérie; Tsapis, Nicolas; Fattal, Elias

2016-03-01

The conversion of colloidal drug carriers/polymeric nanoparticles into dry microparticulate powders (e.g., by spray-drying) is a prominent approach to overcome the aerodynamic limitations of these formulations for delivery via inhalation. However, to what extent such nano-embedded microparticles disintegrate into individual/intact nanoparticles after contacting relevant physiological media has so far not been addressed. Polymeric nanoparticles were spray-dried into nano-embedded microparticles (NEMs) using different amounts of trehalose as embedding matrix excipient. Formulations were characterized and then evaluated for their disintegration behavior after aerosolization onto model mucus. Although a rapid and complete aqueous redispersion was observed for specific excipient/nanoparticle weight ratios (i.e., greater than 1/1), the same formulations revealed no disintegration after deposition onto a static mucus layer. Double-labeled NEMs powders (i.e., dual color staining of polymeric nanoparticles and trehalose) demonstrated rapid matrix dissolution, while the nanoparticle aggregates persisted. When deposited onto agitated mucus, however, sufficient disintegration of NEMs into individual polymeric nanoparticles was observed. These findings indicate that mechanical forces are necessary to overcome the attraction between individual nanoparticles found within the NEMs. Thus, it remains questionable whether the lung mechanics (e.g., breathing, mucociliary clearance) acting on these formulations will contribute to the overall disintegration process. Copyright © 2015 Elsevier B.V. All rights reserved.

Surface plasmon resonance enhanced light absorption and wavelength tuneable in gold-coated iron oxide spherical nanoparticle

NASA Astrophysics Data System (ADS)

Dasri, Thananchai; Chingsungnoen, Artit

2018-06-01

Surface plasmon in nano-sized particles, such as gold, silver, copper and their composites, has recently attracted a great deal of attention due to its possible uses in many applications, especially in life sciences. It is desirable for application devices with a tenability of surface plasmon wavelength and optical properties enhancement. This article presents enhanced optical light absorption and tunable wavelength in gold-coated magnetite (Fe3O4@Au core-shell) nanoparticles embedded in water using the theoretical method of discrete dipole approximation (DDA). The absorption spectra in the wavelengths from 350 to 900 nm were found to be the spectra obtained from Fe3O4@Au core-shell nanoparticles, and when compared with pure Fe3O4 nanoparticles, the surface plasmon resonance can be enhanced and tuned over the entire visible spectrum (viz. 350-800 nm) of the electromagnetic spectrum by varying the Au shell thickness (2-5 nm). Similarly, the Faraday rotation spectra can also be obtained.

Native amorphous nanoheterogeneity in gallium germanosilicates as a tool for driving Ga2O3 nanocrystal formation in glass for optical devices.

PubMed

Sigaev, Vladimir N; Golubev, Nikita V; Ignat'eva, Elena S; Champagnon, Bernard; Vouagner, Dominique; Nardou, Eric; Lorenzi, Roberto; Paleari, Alberto

2013-01-07

Nanoparticles in amorphous oxides are a powerful tool for embedding a wide range of functions in optical glasses, which are still the best solutions in several applications in the ever growing field of photonics. However, the control of the nanoparticle size inside the host material is often a challenging task, even more challenging when detrimental effects on light transmittance have to be avoided. Here we show how the process of phase separation and subsequent nanocrystallization of a Ga-oxide phase can be controlled in germanosilicates - prototypal systems in optical telecommunications - starting from a Ga-modified glass composition designed to favour uniform liquid-liquid phase separation in the melt. Small angle neutron scattering data demonstrate that nanosized structuring occurs in the amorphous as-quenched glass and gives rise to initially smaller nanoparticles, by heating, as in a secondary phase separation. By further heating, the nanophase evolves with an increase of nanoparticle gyration radius, from a few nm to a saturation value of about 10 nm, through an initial growing process followed by an Ostwald ripening mechanism. Nanoparticles finally crystallize, as indicated by transmission electron microscopy and X-ray diffraction, as γ-Ga(2)O(3)- a metastable gallium oxide polymorph. Infrared reflectance and photoluminescence, together with the optical absorption of Ni ions used as a probe, give an indication of the underlying interrelated processes of the structural change in the glass and in the segregated phase. As a result, our data give for the first time a rationale for designing Ga-modified germanosilicates at the nanoscale, with the perspective of a detailed nanostructuring control.

Bio-inspired formation of functional calcite/metal oxide nanoparticle composites.

PubMed

Kim, Yi-Yeoun; Schenk, Anna S; Walsh, Dominic; Kulak, Alexander N; Cespedes, Oscar; Meldrum, Fiona C

2014-01-21

Biominerals are invariably composite materials, where occlusion of organic macromolecules within single crystals can significantly modify their properties. In this article, we take inspiration from this biogenic strategy to generate composite crystals in which magnetite (Fe3O4) and zincite (ZnO) nanoparticles are embedded within a calcite single crystal host, thereby endowing it with new magnetic or optical properties. While growth of crystals in the presence of small molecules, macromolecules and particles can lead to their occlusion within the crystal host, this approach requires particles with specific surface chemistries. Overcoming this limitation, we here precipitate crystals within a nanoparticle-functionalised xyloglucan gel, where gels can also be incorporated within single crystals, according to their rigidity. This method is independent of the nanoparticle surface chemistry and as the gel maintains its overall structure when occluded within the crystal, the nanoparticles are maintained throughout the crystal, preventing, for example, their movement and accumulation at the crystal surface during crystal growth. This methodology is expected to be quite general, and could be used to endow a wide range of crystals with new functionalities.

Environment effect on the acoustic vibration of metal nanoparticles

NASA Astrophysics Data System (ADS)

Voisin, C.; Christofilos, D.; Del Fatti, N.; Vallée, F.

2002-05-01

The impact of the environment on the frequency and damping of the breathing acoustic mode of noble metal nanoparticle is discussed using the model of isotropic homogeneous elastic spheres embedded in an elastic medium. The results are compared to the experimental investigations performed in glass embedded silver nanoparticles and gold colloids using a time-resolved pump-probe technique.

Carrier transport in flexible organic bistable devices of ZnO nanoparticles embedded in an insulating poly(methyl methacrylate) polymer layer.

PubMed

Son, Dong-Ick; Park, Dong-Hee; Choi, Won Kook; Cho, Sung-Hwan; Kim, Won-Tae; Kim, Tae Whan

2009-05-13

The bistable effects of ZnO nanoparticles embedded in an insulating poly(methyl methacrylate) (PMMA) polymer single layer by using flexible polyethylene terephthalate (PET) substrates were investigated. Transmission electron microscopy (TEM) images revealed that ZnO nanoparticles were formed inside the PMMA polymer layer. Current-voltage (I-V) measurement on the Al/ZnO nanoparticles embedded in an insulating PMMA polymer layer/ITO/PET structures at 300 K showed a nonvolatile electrical bistability behavior with a flat-band voltage shift due to the existence of the ZnO nanoparticles, indicative of trapping, storing, and emission of charges in the electronic states of the ZnO nanoparticles. The carrier transport mechanism of the bistable behavior for the fabricated organic bistable device (OBD) structures is described on the basis of the I-V results by analyzing the effect of space charge.

Beyond Traditional Hyperthermia: In Vivo Cancer Treatment with Magnetic-Responsive Mesoporous Silica Nanocarriers.

PubMed

Guisasola, Eduardo; Asín, Laura; Beola, Lilianne; de la Fuente, Jesús M; Baeza, Alejandro; Vallet-Regí, María

2018-04-18

In this study, we present an innovation in the tumor treatment in vivo mediated by magnetic mesoporous silica nanoparticles. This device was built with iron oxide magnetic nanoparticles embedded in a mesoporous silica matrix and coated with an engineered thermoresponsive polymer. The magnetic nanoparticles act as internal heating sources under an alternating magnetic field (AMF) that increase the temperature of the surroundings, provoking the polymer transition and consequently the release of a drug trapped inside the silica pores. By a synergic effect between the intracellular hyperthermia and chemotherapy triggered by AMF application, significant tumor growth inhibition was achieved in 48 h after treatment. Furthermore, the small magnetic loading used in the experiments indicates that the treatment is carried out without a global temperature rise of the tissue, which avoids the problem of the necessity to employ large amounts of magnetic cores, as is common in current magnetic hyperthermia.

A Unique 3D Nitrogen-Doped Carbon Composite as High-Performance Oxygen Reduction Catalyst

PubMed Central

Karunagaran, Ramesh; Tung, Tran Thanh; Tran, Diana; Coghlan, Campbell; Doonan, Christian

2017-01-01

The synthesis and properties of an oxygen reduction catalyst based on a unique 3-dimensional (3D) nitrogen doped (N-doped) carbon composite are described. The composite material is synthesised via a two-step hydrothermal and pyrolysis method using bio-source low-cost materials of galactose and melamine. Firstly, the use of iron salts and galactose to hydrothermally produceiron oxide (Fe2O3) magnetic nanoparticle clusters embedded carbon spheres. Secondly, magnetic nanoparticles diffused out of the carbon sphere when pyrolysed in the presence of melamine as nitrogen precursor. Interestingly, many of these nanoparticles, as catalyst-grown carbon nanotubes (CNTs), resulted in the formation of N-doped CNTs and N-doped carbon spheres under the decomposition of carbon and a nitrogen environment. The composite material consists of integrated N-doped carbon microspheres and CNTs show high ORR activity through a predominantly four-electron pathway. PMID:28792432

Scanning capacitance microscopy of ErAs nanoparticles embedded in GaAs pn junctions

NASA Astrophysics Data System (ADS)

Park, K. W.; Nair, H. P.; Crook, A. M.; Bank, S. R.; Yu, E. T.

2011-09-01

Scanning capacitance microscopy is used to characterize the electronic properties of ErAs nanoparticles embedded in GaAs pn junctions grown by molecular beam epitaxy. Voltage-dependent capacitance images reveal localized variations in subsurface electronic structure near buried ErAs nanoparticles at lateral length scales of 20-30 nm. Numerical modeling indicates that these variations arise from inhomogeneities in charge modulation due to Fermi level pinning behavior associated with the embedded ErAs nanoparticles. Statistical analysis of image data yields an average particle radius of 6-8 nm—well below the direct resolution limit in scanning capacitance microscopy but discernible via analysis of patterns in nanoscale capacitance images.

Cobalt-embedded carbon nanofiber derived from a coordination polymer as a highly efficient heterogeneous catalyst for activating oxone in water.

PubMed

Lin, Kun-Yi Andrew; Tong, Wai-Chi; Du, Yunchen

2018-03-01

Carbon fiber (CF) supported cobalt nanoparticles (NPs) are promising catalysts for activating Oxone because carbon is non-metal and earth-abundant, and CF-based catalysts exhibit a high aspect ratio, which affords more accessible and dense catalytic sites. Nevertheless, most of CF-supported catalysts are fabricated by post-synthetic methods, which involve complicated preparations. More importantly, metallic NPs are attached to the outer surface of CF rather than embedded within CF. However, there is still a great demand for developing Co-bearing carbon fibers for Oxone activation via simple and effective methods. Thus, this study proposes to develop a cobalt NP-embedded carbon nanofiber (CCNF) by a simple hydrothermal reaction of Co and nitrilotriacetic acid (NA), followed by one-step carbonization. Owing to the coordinative structure of CoNA, the derivative CCNF exhibits a fibrous carbon matrix embedded with evenly distributed and densely packed Co 3 O 4 and magnetic Co 0 nanoparticles. The fibrous structure, magnetism and embedded Co NPs enable CCNF to be a promising catalyst for Oxone activation. As degradation of Rhodamine B (RhB) is selected as a model reaction, CCNF not only rapidly activates Oxone to fully degrade RhB but also shows a much higher catalytic activity than the most common Oxone activator, Co 3 O 4 . CCNF also exhibits the lowest activation energy than any reported catalysts for Oxone activation to degrade RhB. In addition, CCNF could be re-used to activate Oxone for RhB degradation. These results indicate that CCNF is a conveniently prepared and highly effective fibrous Co/C hybrid material for activating Oxone to oxidize contaminants in water. Copyright © 2017. Published by Elsevier Ltd.

Metal-organic frameworks as selectivity regulators for hydrogenation reactions

NASA Astrophysics Data System (ADS)

Zhao, Meiting; Yuan, Kuo; Wang, Yun; Li, Guodong; Guo, Jun; Gu, Lin; Hu, Wenping; Zhao, Huijun; Tang, Zhiyong

2016-11-01

Owing to the limited availability of natural sources, the widespread demand of the flavouring, perfume and pharmaceutical industries for unsaturated alcohols is met by producing them from α,β-unsaturated aldehydes, through the selective hydrogenation of the carbon-oxygen group (in preference to the carbon-carbon group). However, developing effective catalysts for this transformation is challenging, because hydrogenation of the carbon-carbon group is thermodynamically favoured. This difficulty is particularly relevant for one major category of heterogeneous catalyst: metal nanoparticles supported on metal oxides. These systems are generally incapable of significantly enhancing the selectivity towards thermodynamically unfavoured reactions, because only the edges of nanoparticles that are in direct contact with the metal-oxide support possess selective catalytic properties; most of the exposed nanoparticle surfaces do not. This has inspired the use of metal-organic frameworks (MOFs) to encapsulate metal nanoparticles within their layers or inside their channels, to influence the activity of the entire nanoparticle surface while maintaining efficient reactant and product transport owing to the porous nature of the material. Here we show that MOFs can also serve as effective selectivity regulators for the hydrogenation of α,β-unsaturated aldehydes. Sandwiching platinum nanoparticles between an inner core and an outer shell composed of an MOF with metal nodes of Fe3+, Cr3+ or both (known as MIL-101; refs 19, 20, 21) results in stable catalysts that convert a range of α,β-unsaturated aldehydes with high efficiency and with significantly enhanced selectivity towards unsaturated alcohols. Calculations reveal that preferential interaction of MOF metal sites with the carbon-oxygen rather than the carbon-carbon group renders hydrogenation of the former by the embedded platinum nanoparticles a thermodynamically favoured reaction. We anticipate that our basic design strategy will allow the development of other selective heterogeneous catalysts for important yet challenging transformations.

Metal-organic frameworks as selectivity regulators for hydrogenation reactions.

PubMed

Zhao, Meiting; Yuan, Kuo; Wang, Yun; Li, Guodong; Guo, Jun; Gu, Lin; Hu, Wenping; Zhao, Huijun; Tang, Zhiyong

2016-11-03

Owing to the limited availability of natural sources, the widespread demand of the flavouring, perfume and pharmaceutical industries for unsaturated alcohols is met by producing them from α,β-unsaturated aldehydes, through the selective hydrogenation of the carbon-oxygen group (in preference to the carbon-carbon group). However, developing effective catalysts for this transformation is challenging, because hydrogenation of the carbon-carbon group is thermodynamically favoured. This difficulty is particularly relevant for one major category of heterogeneous catalyst: metal nanoparticles supported on metal oxides. These systems are generally incapable of significantly enhancing the selectivity towards thermodynamically unfavoured reactions, because only the edges of nanoparticles that are in direct contact with the metal-oxide support possess selective catalytic properties; most of the exposed nanoparticle surfaces do not. This has inspired the use of metal-organic frameworks (MOFs) to encapsulate metal nanoparticles within their layers or inside their channels, to influence the activity of the entire nanoparticle surface while maintaining efficient reactant and product transport owing to the porous nature of the material. Here we show that MOFs can also serve as effective selectivity regulators for the hydrogenation of α,β-unsaturated aldehydes. Sandwiching platinum nanoparticles between an inner core and an outer shell composed of an MOF with metal nodes of Fe 3+ , Cr 3+ or both (known as MIL-101; refs 19, 20, 21) results in stable catalysts that convert a range of α,β-unsaturated aldehydes with high efficiency and with significantly enhanced selectivity towards unsaturated alcohols. Calculations reveal that preferential interaction of MOF metal sites with the carbon-oxygen rather than the carbon-carbon group renders hydrogenation of the former by the embedded platinum nanoparticles a thermodynamically favoured reaction. We anticipate that our basic design strategy will allow the development of other selective heterogeneous catalysts for important yet challenging transformations.

Active systems based on silver-montmorillonite nanoparticles embedded into bio-based polymer matrices for packaging applications.

PubMed

Incoronato, A L; Buonocore, G G; Conte, A; Lavorgna, M; Nobile, M A Del

2010-12-01

Silver-montmorillonite (Ag-MMT) antimicrobial nanoparticles were obtained by allowing silver ions from nitrate solutions to replace the Na(+) of natural montmorillonite and to be reduced by thermal treatment. The Ag-MMT nanoparticles were embedded in agar, zein, and poly(ε-caprolactone) polymer matrices. These nanocomposites were tested in vitro with a three-strain cocktail of Pseudomonas spp. to assess antimicrobial effectiveness. The results indicate that Ag-MMT nanoparticles embedded into agar may have antimicrobial activity against selected spoilage microorganisms. No antimicrobial effects were recorded with active zein and poly(ε-caprolactone). The water content of the polymeric matrix was the key parameter associated with antimicrobial effectiveness of this active system intended for food packaging applications.

Synthesis of silica coated zinc oxide–poly(ethylene-co-acrylic acid) matrix and its UV shielding evaluation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ramasamy, Mohankandhasamy; Kim, Yu Jun; Gao, Haiyan

Graphical abstract: - Highlights: • Well layer thickness controlled silica shell was made on ZnO nanoparticles. • PEAA, an interfacial agent is used to make nanocomposite–polymer matrix by twin-screw extruder. • Si-ZnO/PEAA matrix is highly stable and UV protective as compared to ZnO/PEAA matrix. • Nanoparticle embedded polymer matrix is suggested to make UV shielding fabrics with Nylon4. - Abstract: Silica coated zinc oxide nanoparticles (Si-ZnO NPs) (7 nm thick) were synthesized successfully and melt blended with poly(ethylene-co-acrylic acid) (PEAA resin) to improving ultraviolet (UV) shielding of zinc oxide nanoparticles (ZnO NPs). The photostability of both the ZnO NPs andmore » Si-ZnO NPs were analyzed by the difference in photoluminescence (PL) and by methylene blue (MB) degradation. Photo-degradation studies confirmed that Si-ZnO NPs are highly photostable compared to ZnO NPs. The melt blended matrices were characterized by field emission scanning electron microscopy interfaced with energy dispersive X-ray spectroscopy (FE-SEM-EDX). The UV shielding property was analyzed from the transmittance spectra of UV–visible (UV–vis) spectroscopy. The results confirmed fine dispersion of thick Si-ZnO NPs in the entire resin matrix. Moreover, the Si-ZnO/PEAA showed about 97% UV shielding properties than the ZnO/PEAA.« less

Mussel-inspired approach to constructing robust cobalt-embedded N-doped carbon nanosheet toward enhanced sulphate radical-based oxidation

NASA Astrophysics Data System (ADS)

Zeng, Tao; Zhang, Haiyan; He, Zhiqiao; Chen, Jianmeng; Song, Shuang

2016-09-01

Heterogeneous sulphate radical based advanced oxidation processes (SR-AOPs) have lately been raised as a promising candidate for water treatment. Despite the progress made, either the stability or the performance of the current catalysts is still far from satisfactory for practical applications. Herein, using polydopamine-cobalt ion complex that inspired by mussel proteins as medium, we facilely fabricate a robust SR-AOPs catalyst with cobalt nanoparticles (NPs) embedded in nitrogen-doped reduced graphene oxide matrix (NRGO@Co). The NRGO scaffold with high porosity and surface area not only stabilizes the NPs but also greatly facilitates the accessibility and adsorption of substrates to the active sites. With the synergistic effect arising from the NRGO and Co NPs, the NRGO@Co hybrid catalyst exhibits enhanced catalytic activity for activation of peroxymonosulfate (PMS) to degrade organic pollutants in water. Furthermore, taking advantage of the favorable magnetic properties, the catalyst can be easily recycled and reused for at least 4 runs with negligible loss of activity. Coupled with systematic investigation in terms of influential factors, mineralization, and radicals identification, make the catalyst hold significant potential for application in remediation of organic pollutants in water.

Irradiation effect of low-energy ion on polyurethane nanocoating containing metal oxide nanoparticles

NASA Astrophysics Data System (ADS)

Verma, Jaya; Nigam, Subhasha; Sinha, Surbhi; Sikarwar, B. S.; Bhattacharya, Arpita

2017-12-01

Irradiation effect of low-energy ion beam has been investigated on nanocoating developed with silica, titania and silica-titania core-shell nanoparticles embedded in an organic binder for nanopaint application. In this work, we have taken polyurethane as a model organic binder. Silica nanoparticles have been prepared through sol-gel synthesis with a particle size of 85 nm. Titania and core-shell nanoparticles have been prepared through both sol-gel and peptization process. Particle sizes obtained were 107 nm for titania and 240 nm for core-shell nanoparticles prepared through sol-gel process and 75 nm for TiO2 and 144 nm for core-shell nanoparticles prepared through peptization process. The coating formulations were developed with the above nanoparticles individually and nanoparticle concentration was varied from 1 to 6 wt% and the best performance in terms of hydrophobicity was obtained with 4 wt % of the nanoparticles in polyurethane coating formulation. All the coating formulations prepared were applied on a glass substrate and dried at 100°C. The dry film thickness obtained was around 100 µm in each case. These films dried on glass substrate were irradiated by nitrogen and argon ion beam with energy of 26 keV at fluences of 1014 to 1016 ions/cm2. The anti-algal property of the irradiated samples was improved and hydrophobicity was reduced.

Enhanced emission of nile red fluorescent nanoparticles embedded in hybrid sol-gel glasses.

PubMed

Ferrer, Maria L; del Monte, Francisco

2005-01-13

Highly fluorescent Nile Red (NR) nanoparticles embedded in a hybrid sol-gel glass are reported. The crystallite growth within the confined system created by the porous hybrid matrix results in NR nanoparticles of averaged dimensions below 36 nm. The preparation process allows for the control of both the conformation adopted by single NR molecules prior to aggregation (e.g., near planar) and the configuration of the aggregates (e.g., oblique with phi < 54.7 degrees) prior to their assembly in the supramolecular architecture which ultimately forms the nanoparticles. The full preservation of the fluorescent configuration of the aggregates in the nanoparticles is confirmed through the application of the exciton theory, and it is responsible for the significant increase of the fluorescence emission intensity (e.g., up to 525- and 70-fold as compared to that obtained for single NR molecules embedded in pure and hybrid silica glasses, respectively).

Cobalt Nanoparticle-Embedded Porous Carbon Nanofibers with Inherent N- and F-Doping as Binder-Free Bifunctional Catalysts for Oxygen Reduction and Evolution Reactions.

PubMed

Singhal, Richa; Kalra, Vibha

2017-01-18

Efficient, low-cost, non-precious metal-based, and stable bifunctional electrocatalysts are key to various energy storage and conversion devices such as regenerative fuel cells and metal-air batteries. In this work, we report cobalt nanoparticle-embedded porous carbon nanofibers with inherent N- and F-doping as binder-free bifunctional electrocatalysts with excellent activity for both the oxygen reduction and oxygen evolution reaction (ORR/OER) in an alkaline medium. Single-step electrospinning of a solution of the polymer mixture (carbon precursor) and the cobalt precursor followed by controlled pyrolysis with an intermediate reduction step in H 2 (to reduce cobalt oxides to cobalt) was utilized to synthesize an integrated freestanding catalyst. The fabricated catalyst with effective structural and electronic interaction between the cobalt metal nanoparticles and the N- and F-doped carbon defect sites showed enhanced catalytic properties compared to the benchmark catalysts for ORR and OER (Pt, Ir, and Ru). The ORR potential at the current density of -3 mA cm -2 was 0.81 V RHE and the OER potential at a current density of 10 mA cm -2 was 1.595 V RHE , resulting in a ΔE of only 0.785 V. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Multifunctional microvalves control by optical illumination on nanoheaters and its application in centrifugal microfluidic devices.

PubMed

Park, Jong-Myeon; Cho, Yoon-Kyoung; Lee, Beom-Seok; Lee, Jeong-Gun; Ko, Christopher

2007-05-01

Valving is critical in microfluidic systems. Among many innovative microvalves used in lab-on-a-chip applications, phase change based microvalves using paraffin wax are particularly attractive for disposable biochip applications because they are simple to implement, cost-effective and biocompatible. However, previously reported paraffin-based valves require embedded microheaters and therefore multi-step operation of many microvalves was a difficult problem. Besides, the operation time was relatively long, 2-10 s. In this paper, we report a unique phase change based microvalve for rapid and versatile operation of multiple microvalves using a single laser diode. The valve is made of nanocomposite materials in which 10 nm-sized iron oxide nanoparticles are dispersed in paraffin wax and used as nanoheaters when excited by laser irradiation. Laser light of relatively weak intensity was able to melt the paraffin wax with the embedded iron oxide nanoparticles, whereas even a very intense laser beam does not melt wax alone. The microvalves are leak-free up to 403.0 +/- 7.6 kPa and the response times to operate both normally closed and normally opened microvalves are less than 0.5 s. Furthermore, a sequential operation of multiple microvalves on a centrifugal microfluidic device using a single laser diode was demonstrated. It showed that the optical control of multiple microvalves is fast, robust, simple to operate, and requires minimal chip space and thus is well suited for fully integrated lab-on-a-chip applications.

From Mixed-Metal MOFs to Carbon-Coated Core-Shell Metal Alloy@Metal Oxide Solid Solutions: Transformation of Co/Ni-MOF-74 to CoxNi1-x@CoyNi1-yO@C for the Oxygen Evolution Reaction.

PubMed

Sun, Dengrong; Ye, Lin; Sun, Fangxiang; García, Hermenegildo; Li, Zhaohui

2017-05-01

Calcination of the mixed-metal species Co/Ni-MOF-74 leads to the formation of carbon-coated Co x Ni 1-x @Co y Ni 1-y O with a metal core diameter of ∼3.2 nm and a metal oxide shell thickness of ∼2.4 nm embedded uniformly in the ligand-derived carbon matrix. The close proximity of Co and Ni in the mixed-metal Co/Ni-MOF-74 promotes the metal alloying and the formation of a solid solution of metal oxide during the calcination process. The presence of the tightly coated carbon shell prohibits particle agglomeration and stabilizes the Co x Ni 1-x @Co y Ni 1-y O nanoparticles in small size. The Co x Ni 1-x @Co y Ni 1-y O@C derived from Co/Ni-MOF-74 nanocomposites show superior performance for the oxygen evolution reaction (OER). The use of mixed-metal MOFs as precursors represents a powerful strategy for the fabrication of metal alloy@metal oxide solid solution nanoparticles in small size. This method also holds great promise in the development of multifunctional carbon-coated complex core-shell metal/metal oxides owing to the diversified MOF structures and their flexible chemistry.

The influence of mannitol on morphology and disintegration of spray-dried nano-embedded microparticles.

PubMed

Torge, Afra; Grützmacher, Philipp; Mücklich, Frank; Schneider, Marc

2017-06-15

Nano-embedded microparticles represent a promising approach to deliver nanoparticles to the lungs. Microparticles with an appropriate aerodynamic diameter enable an application by dry powder inhaler and the transport of nanoparticles into the airways. By disintegration after deposition, nanoparticles can be released to exhibit their advantages such as a sustained drug release and delivery of the drug across the mucus barrier. The use of an appropriate matrix excipient to embed the nanoparticles is essential for the necessary disintegration and release of nanoparticles. In this context we investigated the influence of mannitol on the morphology, aerodynamic properties and disintegration behavior of nano-embedded microparticles. PLGA nanoparticles and mannitol were spray dried each as sole component and in combination in three different ratios. An influence of the mannitol content on the morphology was observed. Pure mannitol microparticles were solid and spherical, while the addition of nanoparticles resulted in raisin-shaped hollow particles. The different morphologies can be explained by diffusion processes of the compounds described by the Péclet-number. All powders showed suitable aerodynamic properties. By dispersion of the powders in simulated lung fluid, initial nanoparticle sizes could be recovered for samples containing mannitol. The fraction of redispersed nanoparticles was increased with increasing mannitol content. To evaluate the disintegration under conditions with higher comparability to the in vivo situation, spray-dried powders were exposed to >90% relative humidity. The disintegration behavior was monitored by analyzing roughness values by white light interferometry and supporting SEM imaging. The exposure to high relative humidity was shown to be sufficient for disintegration of the microparticles containing mannitol, releasing morphologically unchanged nanoparticles. With increasing mannitol content, the disintegration occurred faster and to a higher degree. Under these conditions, microparticles only composed of nanoparticles did not disintegrate. By enabling the release of nanoparticles from nano-embedded microparticles, mannitol was shown to be an ideal excipient to convert nanoparticles by spray drying into an inhalable dry power formulation. Copyright © 2017 Elsevier B.V. All rights reserved.

Intracellular trafficking of silicon particles and logic-embedded vectors

NASA Astrophysics Data System (ADS)

Ferrati, Silvia; Mack, Aaron; Chiappini, Ciro; Liu, Xuewu; Bean, Andrew J.; Ferrari, Mauro; Serda, Rita E.

2010-08-01

Mesoporous silicon particles show great promise for use in drug delivery and imaging applications as carriers for second-stage nanoparticles and higher order particles or therapeutics. Modulation of particle geometry, surface chemistry, and porosity allows silicon particles to be optimized for specific applications such as vascular targeting and avoidance of biological barriers commonly found between the site of drug injection and the final destination. In this study, the intracellular trafficking of unloaded carrier silicon particles and carrier particles loaded with secondary iron oxide nanoparticles was investigated. Following cellular uptake, membrane-encapsulated silicon particles migrated to the perinuclear region of the cell by a microtubule-driven mechanism. Surface charge, shape (spherical and hemispherical) and size (1.6 and 3.2 μm) of the particle did not alter the rate of migration. Maturation of the phagosome was associated with an increase in acidity and acquisition of markers of late endosomes and lysosomes. Cellular uptake of iron oxide nanoparticle-loaded silicon particles resulted in sorting of the particles and trafficking to unique destinations. The silicon carriers remained localized in phagosomes, while the second stage iron oxide nanoparticles were sorted into multi-vesicular bodies that dissociated from the phagosome into novel membrane-bound compartments. Release of iron from the cells may represent exocytosis of iron oxide nanoparticle-loaded vesicles. These results reinforce the concept of multi-functional nanocarriers, in which different particles are able to perform specific tasks, in order to deliver single- or multi-component payloads to specific sub-cellular compartments.Mesoporous silicon particles show great promise for use in drug delivery and imaging applications as carriers for second-stage nanoparticles and higher order particles or therapeutics. Modulation of particle geometry, surface chemistry, and porosity allows silicon particles to be optimized for specific applications such as vascular targeting and avoidance of biological barriers commonly found between the site of drug injection and the final destination. In this study, the intracellular trafficking of unloaded carrier silicon particles and carrier particles loaded with secondary iron oxide nanoparticles was investigated. Following cellular uptake, membrane-encapsulated silicon particles migrated to the perinuclear region of the cell by a microtubule-driven mechanism. Surface charge, shape (spherical and hemispherical) and size (1.6 and 3.2 μm) of the particle did not alter the rate of migration. Maturation of the phagosome was associated with an increase in acidity and acquisition of markers of late endosomes and lysosomes. Cellular uptake of iron oxide nanoparticle-loaded silicon particles resulted in sorting of the particles and trafficking to unique destinations. The silicon carriers remained localized in phagosomes, while the second stage iron oxide nanoparticles were sorted into multi-vesicular bodies that dissociated from the phagosome into novel membrane-bound compartments. Release of iron from the cells may represent exocytosis of iron oxide nanoparticle-loaded vesicles. These results reinforce the concept of multi-functional nanocarriers, in which different particles are able to perform specific tasks, in order to deliver single- or multi-component payloads to specific sub-cellular compartments. Electronic supplementary information (ESI) available: Confocal microscopy image showing internalized negative particles, and movie of the intracellular migration of silicon particles. See DOI: 10.1039/c0nr00227e

One-step synthesis of magnetic chitosan for controlled release of 5-hydroxytryptophan

NASA Astrophysics Data System (ADS)

Santos Menegucci, Jucély dos; Santos, Mac-Kedson Medeiros Salviano; Dias, Diego Juscelino Santos; Chaker, Juliano Alexandre; Sousa, Marcelo Henrique

2015-04-01

In this work, nanoparticles of chitosan embedded with 25% (w/w) of iron oxide magnetic nanoparticles (magnetite/maghemite) with narrow size-distribution and with a loading efficiency of about 80% for 5-hydroxytryptophan (5-HTP), which is a chemical precursor in the biosynthesis of important neurotransmitters as serotonin, were synthesized with an initial mass ratio of 5-HTP/magnetic chitosan=1.2, using homogeneous precipitation by urea decomposition, in an efficient one-step procedure. Characterization of morphology, structure and surface were performed by XRD, TEM, FTIR, TGA, magnetization and zeta potential measurements, while drug loading and drug releasing were investigated using UV-vis spectroscopy. Kinetic drug release experiments under different pH conditions revealed a pH-sensitivecontrolled-release system, ruled by polymer swelling and/or particle dissolution.

Magnetic Nanoparticles Embedded in a Silicon Matrix

PubMed Central

Granitzer, Petra; Rumpf, Klemens

2011-01-01

This paper represents a short overview of nanocomposites consisting of magnetic nanoparticles incorporated into the pores of a porous silicon matrix by two different methods. On the one hand, nickel is electrochemically deposited whereas the nanoparticles are precipitated on the pore walls. The size of these particles is between 2 and 6 nm. These particles cover the pore walls and form a tube-like arrangement. On the other hand, rather well monodispersed iron oxide nanoparticles, of 5 and 8 nm respectively, are infiltrated into the pores. From their size the particles would be superparamagnetic if isolated but due to magnetic interactions between them, ordering of magnetic moments occurs below a blocking temperature and thus the composite system displays a ferromagnetic behavior. This transition temperature of the nanocomposite can be varied by changing the filling factor of the particles within the pores. Thus samples with magnetic properties which are variable in a broad range can be achieved, which renders this composite system interesting not only for basic research but also for applications, especially because of the silicon base material which makes it possible for today’s process technology. PMID:28879957

Microwave synthesis of ZnO@mSiO₂ for detailed antifungal mode of action study: understanding the insights into oxidative stress.

PubMed

Mitra, Shouvik; Patra, Prasun; Pradhan, Saheli; Debnath, Nitai; Dey, Kushal Kumar; Sarkar, Sampad; Chattopadhyay, Dhrubajyoti; Goswami, Arunava

2015-04-15

A simple chemical method has been devised for deliberate incorporation of zinc oxide nanoparticles (ZNPs) within mesoporous nanosilica (mSiO2) matrix to yield zinc oxide nanoparticles embedded in mesoporous nanosilica (ZnO@mSiO2). ZnO@mSiO2 inhibited the growth of four strains of fungi in a dose dependant manner. A series of biochemical assays revealed generation of oxidative stress from ZnO@mSiO2 for such biocidal response. We proposed transient superoxide and its subsequent conversion to H2O2 played a pivotal role behind such biocidal response as revealed from our systematic evaluation. This resulted morphological alteration of fungi through increase in number of facets, in correlation we found up-regulation in oxidative stress related genes. Bioavailability within the fungal sample was confirmed from microscopic, spectroscopic, biophysical techniques. Protein carbonylation of fungal species was the chemical outcome of such above mentioned stress and quantified by high performance liquid chromatography (HPLC) via subsequent hydrazone derivatization. Several in vitro and in vivo evaluations revealed the biocompatibility of ZnO@mSiO2. Altogether this report claims a new biocidal agent with a detailed mode of action focusing on the origin and quantification of oxidative stress through biophysical and biochemical techniques for the first time for real time applications. Copyright © 2014 Elsevier Inc. All rights reserved.

Electrochemical determination of dopamine and ascorbic acid at a novel gold nanoparticles distributed poly(4-aminothiophenol) modified electrode.

PubMed

Gopalan, Anantha Iyengar; Lee, Kwang-Pill; Manesh, Kalayil Manian; Santhosh, Padmanabhan; Kim, Jun Heon; Kang, Jae Soo

2007-03-15

A modified electrode is fabricated by embedding gold nanoparticles into a layer of electroactive polymer, poly(4-aminothiophenol) (PAT) on the surface of glassy carbon (GC) electrode. Cyclic voltammetry (CV) is performed to deposit PAT and concomitantly deposit Au nanoparticles. Field emission transmission electron microscopic image of the modified electrode, PAT-Au(nano)-ME, indicates the presence of uniformly distributed Au nanoparticles having the sizes of 8-10nm. Electrochemical behavior of the PAT-Au(nano)-ME towards detection of ascorbic acid (AA) and dopamine (DA) is studied using CV. Electrocatalytic determination of DA in the presence of fixed concentration of AA and vice versa, are studied using differential pulse voltammetry (DPV). PAT-Au(nano)-ME exhibits two well defined anodic peaks at the potential of 75 and 400mV for the oxidation of AA and DA, respectively with a potential difference of 325mV. Further, the simultaneous determination of AA and DA is studied by varying the concentration of AA and DA. PAT-Au(nano)-ME exhibits selectivity and sensitivity for the simultaneous determination of AA and DA without fouling by the oxidation products of AA or DA. PAT and Au nanoparticles provide synergic influence on the accurate electrochemical determination of AA or DA from a mixture having any one of the component (AA or DA) in excess. The practical analytical utilities of the PAT-Au(nano)-ME are demonstrated by the determination of DA and AA in dopamine hydrochloride injection and human blood serum samples.

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.

Sustained Nitric Oxide-Releasing Nanoparticles Interfere with Methicillin-Resistant Staphylococcus aureus Adhesion and Biofilm Formation in a Rat Central Venous Catheter Model

PubMed Central

Mihu, Mircea Radu; Cabral, Vitor; Pattabhi, Rodney; Tar, Moses T.; Davies, Kelvin P.; Friedman, Adam J.

2016-01-01

ABSTRACT Staphylococcus aureus is frequently isolated in the setting of infections of indwelling medical devices, which are mediated by the microbe's ability to form biofilms on a variety of surfaces. Biofilm-embedded bacteria are more resistant to antimicrobial agents than their planktonic counterparts and often cause chronic infections and sepsis, particularly in patients with prolonged hospitalizations. In this study, we demonstrate that sustained nitric oxide-releasing nanoparticles (NO-np) interfere with S. aureus adhesion and prevent biofilm formation on a rat central venous catheter (CVC) model of infection. Confocal and scanning electron microscopy showed that NO-np-treated staphylococcal biofilms displayed considerably reduced thicknesses and bacterial numbers compared to those of control biofilms in vitro and in vivo, respectively. Although both phenotypes, planktonic and biofilm-associated staphylococci, of multiple clinical strains were susceptible to NO-np, bacteria within biofilms were more resistant to killing than their planktonic counterparts. Furthermore, chitosan, a biopolymer found in the exoskeleton of crustaceans and structurally integrated into the nanoparticles, seems to add considerable antimicrobial activity to the technology. Our findings suggest promising development and translational potential of NO-np for use as a prophylactic or therapeutic against bacterial biofilms on CVCs and other medical devices. PMID:27821454

Sustained Nitric Oxide-Releasing Nanoparticles Interfere with Methicillin-Resistant Staphylococcus aureus Adhesion and Biofilm Formation in a Rat Central Venous Catheter Model.

PubMed

Mihu, Mircea Radu; Cabral, Vitor; Pattabhi, Rodney; Tar, Moses T; Davies, Kelvin P; Friedman, Adam J; Martinez, Luis R; Nosanchuk, Joshua D

2017-01-01

Staphylococcus aureus is frequently isolated in the setting of infections of indwelling medical devices, which are mediated by the microbe's ability to form biofilms on a variety of surfaces. Biofilm-embedded bacteria are more resistant to antimicrobial agents than their planktonic counterparts and often cause chronic infections and sepsis, particularly in patients with prolonged hospitalizations. In this study, we demonstrate that sustained nitric oxide-releasing nanoparticles (NO-np) interfere with S. aureus adhesion and prevent biofilm formation on a rat central venous catheter (CVC) model of infection. Confocal and scanning electron microscopy showed that NO-np-treated staphylococcal biofilms displayed considerably reduced thicknesses and bacterial numbers compared to those of control biofilms in vitro and in vivo, respectively. Although both phenotypes, planktonic and biofilm-associated staphylococci, of multiple clinical strains were susceptible to NO-np, bacteria within biofilms were more resistant to killing than their planktonic counterparts. Furthermore, chitosan, a biopolymer found in the exoskeleton of crustaceans and structurally integrated into the nanoparticles, seems to add considerable antimicrobial activity to the technology. Our findings suggest promising development and translational potential of NO-np for use as a prophylactic or therapeutic against bacterial biofilms on CVCs and other medical devices. Copyright © 2016 American Society for Microbiology.

A novel C-shaped, gold nanoparticle coated, embedded polymer waveguide for localized surface plasmon resonance based detection.

PubMed

Prabhakar, Amit; Mukherji, Soumyo

2010-12-21

In this study, a novel embedded optical waveguide based sensor which utilizes localized surface plasmon resonance of gold nanoparticles coated on a C-shaped polymer waveguide is being reported. The sensor, as designed, can be used as an analysis chip for detection of minor variations in the refractive index of its microenvironment, which makes it suitable for wide scale use as an affinity biosensor. The C-shaped waveguide coupled with microfluidic channel was fabricated by single step patterning of SU8 on an oxidized silicon wafer. The absorbance due to the localized surface plasmon resonance (LSPR) of SU8 waveguide bound gold nano particle (GNP) was found to be linear with refractive index changes between 1.33 and 1.37. A GNP coated C-bent waveguide of 200 μ width with a bend radius of 1 mm gave rise to a sensitivity of ~5 ΔA/RIU at 530 nm as compared to the ~2.5 ΔA/RIU (refractive index units) of the same dimension bare C-bend SU8 waveguide. The resolution of the sensor probe was ~2 × 10(-4) RIU.

Tuning the luminescence of ZnO:Eu nanoparticles for applications in biology and medicine

NASA Astrophysics Data System (ADS)

Kaszewski, Jarosław; Kiełbik, Paula; Wolska, Ewelina; Witkowski, Bartłomiej; Wachnicki, Łukasz; Gajewski, Zdzisław; Godlewski, Marek; Godlewski, Michał M.

2018-06-01

Zinc oxide nanoparticles were synthesized with microwave hydrothermal technique and tested as luminescent contrast for biological imaging. Luminescence was activated by Eu3+ ions embedded in the nanoparticle matrix in the increasing concentrations of 1, 5 and 10 %mol. It was found that europium did not create a separate crystalline phase up to the concentration as high as 5 %mol. However, Eu3+ ions did not substitute Zn2+ in the host lattice, but allocated in the low symmetry environment. It was proposed that europium was locating in the inter-grain space or on the surface of nanoparticles. The luminescence intensity in ZnO:Eu, as well as the size of particles, increased with the Eu ion concentration. Moreover, in 10 %mol Eu sample, the separate phase of Eu-hydroxide was identified with crystals of micrometre length. Interestingly, in vivo study revealed, that contrary to the in silico experiments, following gastric gavage, the brightest nanoparticle-related luminescence signal was observed at 1 %mol. concentration of Eu. Since the alimentary uptake of nanoparticles was related to their size, we concluded that the increase in luminescence at 5 and 10 %mol. Eu concentrations was associated with the largest ZnO:Eu and Eu-hydroxide particles that did not cross the gastrointestinal barrier.

Giant enhancement and anomalous thermal hysteresis of saturation moment in magnetic nanoparticles embedded in multiwalled carbon nanotubes.

PubMed

Zhao, Guo-meng; Wang, Jun; Ren, Yang; Beeli, Pieder

2013-06-12

We report high-energy synchrotron X-ray diffraction spectrum and high-temperature magnetic data for multiwalled carbon nanotubes (MWCNTs) embedded with Fe and Fe3O4 nanoparticles. We unambiguously show that the saturation moments of the embedded Fe and Fe3O4 nanoparticles are enhanced by a factor of about 3.0 compared with what would be expected if they would be unembedded. More intriguingly the enhanced moments were completely lost when the sample was heated up to 1120 K, and the lost moments were completely recovered through two more thermal cycles below 1020 K. These novel results cannot be explained by the magnetism of the Fe and Fe3O4 impurity phases, the magnetic proximity effect between magnetic nanoparticles and carbon, and the ballistic transport of MWCNTs.

Metallorganic routes to nanoscale iron and titanium oxide particles encapsulated in mesoporous alumina: formation, physical properties, and chemical reactivity.

PubMed

Schneider, J J; Czap, N; Hagen, J; Engstler, J; Ensling, J; Gütlich, P; Reinoehl, U; Bertagnolli, H; Luis, F; de Jongh, L J; Wark, M; Grubert, G; Hornyak, G L; Zanoni, R

2000-12-01

Iron and titanium oxide nanoparticles have been synthesized in parallel mesopores of alumina by a novel organometallic "chimie douce" approach that uses bis(toluene)iron(0) (1) and bis(toluene)titanium(0) (2) as precursors. These complexes are molecular sources of iron and titanium in a zerovalent atomic state. In the case of 1, core shell iron/iron oxide particles with a strong magnetic coupling between both components, as revealed by magnetic measurements, are formed. Mössbauer data reveal superparamagnetic particle behavior with a distinct particle size distribution that confirms the magnetic measurements. The dependence of the Mössbauer spectra on temperature and particle size is explained by the influence of superparamagnetic relaxation effects. The coexistence of a paramagnetic doublet and a magnetically split component in the spectra is further explained by a distribution in particle size. From Mössbauer parameters the oxide phase can be identified as low-crystallinity ferrihydrite oxide. In agreement with quantum size effects observed in UV-visible studies, TEM measurements determine the size of the particles in the range 5-8 nm. The particles are mainly arranged alongside the pore walls of the alumina template. TiO2 nanoparticles are formed by depositing 2 in mesoporous alumina template. This produces metallic Ti, which is subsequently oxidized to TiO2 (anatase) within the alumina pores. UV-visible studies show a strong quantum confinement effect for these particles. From UV-visible investigations the particle size is determined to be around 2 nm. XPS analysis of the iron- and titania- embedded nanoparticles reveal the presence of Fe2O3 and TiO2 according to experimental binding energies and the experimental line shapes. Ti4+ and Fe3+ are the only oxidation states of the particles which can be determined by this technique. Hydrogen reduction of the iron/iron-oxide nanoparticles at 500 degrees C under flowing H2/N2 produces a catalyst, which is active towards formation of carbon nanotubes by a CVD process. Depending on the reaction conditions, the formation of smaller carbon nanotubes inside the interior of larger carbon nanotubes within the alumina pores can be achieved. This behavior can be understood by means of selectively turning on and off the iron catalyst by adjusting the flow rate of the gaseous carbon precursor in the CVD process.

Antitumor activity of intratracheal inhalation of temozolomide (TMZ) loaded into gold nanoparticles and/or liposomes against urethane-induced lung cancer in BALB/c mice.

PubMed

Hamzawy, Mohamed A; Abo-Youssef, Amira M; Salem, Heba F; Mohammed, Sameh A

2017-11-01

The current study aimed to develop gold nanoparticles (GNPs) and liposome-embedded gold nanoparticles (LGNPs) as drug carriers for temozolomide (TMZ) and investigate the possible therapeutic effects of intratracheal inhalation of nanoformulation of TMZ-loaded gold nanoparticles (TGNPs) and liposome-embedded TGNPs (LTGNPs) against urethane-induced lung cancer in BALB/c mice. Physicochemical characters and zeta potential studies for gold nanoparticles (GNPs) and liposome-embedded gold nanoparticles (LGNPs) were performed. The current study was conducted by inducing lung cancer chemically via repeated exposure to urethane in BALB/C mice. GNPs and LGNPs were exhibited in uniform spherical shape with adequate dispersion stability. GNPs and LGNPs showed no significant changes in comparison to control group with high safety profile, while TGNPs and LTGNPs succeed to improve all biochemical data and histological patterns. GNPs and LGNPs are promising drug carriers and succeeded in the delivery of small and efficient dose of temozolomide in treatment lung cancer. Antitumor activity was pronounced in animal-treated LTGNPs, these effects may be due to synergistic effects resulted from combination of temozolomide and gold nanoparticles and liposomes that may improve the drug distribution and penetration.

An Efficient and Reusable Embedded Ru Catalyst for the Hydrogenolysis of Levulinic Acid to γ-Valerolactone.

PubMed

Wei, Zuojun; Lou, Jiongtao; Su, Chuanmin; Guo, Dechao; Liu, Yingxin; Deng, Shuguang

2017-04-22

To achieve a higher activity and reusability of a Ru-based catalyst, Ru nanoparticles were embedded in N-doped mesoporous carbon through a hard-template method. The catalyst showed excellent catalytic performance (314 h -1 turnover frequency) and recyclability (reusable five times with 3 % activity loss) for the hydrogenolysis of levulinic acid to γ-valerolactone. Compared with the mesoporous carbon without N-doping and conventional activated carbon, the introduction of N-dopant effectively improved the dispersion of Ru nanoparticles, decreased the average size of Ru nanoparticles to as small as 1.32 nm, and improved the adsorption of levulinic acid, which contributed to the increase in the activity of the catalyst. Additionally, the embedding method increased the interaction between Ru nanoparticles and carbon support in contrast with the conventional impregnation method, thus preventing the Ru nanoparticles from migration, aggregation, and leaching from the carbon surface and therefore increasing the reusability of the catalyst. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Magnetic nanocomposites based on phosphorus-containing polymers—structural characterization and thermal analysis

NASA Astrophysics Data System (ADS)

Alosmanov, R. M.; Szuwarzyński, M.; Schnelle-Kreis, J.; Matuschek, G.; Magerramov, A. M.; Azizov, A. A.; Zimmermann, R.; Zapotoczny, S.

2018-04-01

Fabrication of magnetic nanocomposites containing iron oxide nanoparticles formed in situ within a phosphorus-containing polymer matrix as well as its structural characterization and its thermal degradation is reported here. Comparative structural studies of the parent polymer and nanocomposites were performed using FTIR spectroscopy, x-ray diffraction, and atomic force microscopy. The results confirmed the presence of dispersed iron oxide magnetic nanoparticles in the polymer matrix. The formed composite combines the properties of porous polymer carriers and magnetic particles enabling easy separation and reapplication of such polymeric carriers used in, for example, catalysis or environmental remediation. Studies on thermal degradation of the composites revealed that the process proceeds in three stages while a significant influence of the embedded magnetic particles on that process was observed in the first two stages. Magnetic force microscopy studies revealed that nanocomposites and its calcinated form have strong magnetic properties. The obtained results provide a comprehensive characterization of magnetic nanocomposites and the products of their calcination that are important for their possible applications as sorbents (regeneration conditions, processing temperature, disposal, etc).

Assessing bio-available silver released from silver nanoparticles embedded in silica layers using the green algae Chlamydomonas reinhardtii as bio-sensors.

PubMed

Pugliara, Alessandro; Makasheva, Kremena; Despax, Bernard; Bayle, Maxime; Carles, Robert; Benzo, Patrizio; BenAssayag, Gérard; Pécassou, Béatrice; Sancho, Maria Carmen; Navarro, Enrique; Echegoyen, Yolanda; Bonafos, Caroline

2016-09-15

Silver nanoparticles (AgNPs) because of their strong antibacterial activity are widely used in health-care sector and industrial applications. Their huge surface-volume ratio enhances the silver release compared to the bulk material, leading to an increased toxicity for microorganisms sensitive to this element. This work presents an assessment of the toxic effect on algal photosynthesis due to small (size <20nm) AgNPs embedded in silica layers. Two physical approaches were originally used to elaborate the nanocomposite structures: (i) low energy ion beam synthesis and (ii) combined silver sputtering and plasma polymerization. These techniques allow elaboration of a single layer of AgNPs embedded in silica films at defined nanometer distances (from 0 to 7nm) beneath the free surface. The structural and optical properties of the nanostructures were studied by transmission electron microscopy and optical reflectance. The silver release from the nanostructures after 20h of immersion in buffered water was measured by inductively coupled plasma mass spectrometry and ranges between 0.02 and 0.49μM. The short-term toxicity of Ag to photosynthesis of Chlamydomonas reinhardtii was assessed by fluorometry. The obtained results show that embedding AgNPs reduces the interactions with the buffered water free media, protecting the AgNPs from fast oxidation. The release of bio-available silver (impacting on the algal photosynthesis) is controlled by the depth at which AgNPs are located for a given host matrix. This provides a procedure to tailor the toxicity of nanocomposites containing AgNPs. Copyright © 2016 Elsevier B.V. All rights reserved.

Anionic Cerium Oxide Nanoparticles Protect Plant Photosynthesis from Abiotic Stress by Scavenging Reactive Oxygen Species.

PubMed

Wu, Honghong; Tito, Nicholas; Giraldo, Juan P

2017-11-28

Plant abiotic stress leads to accumulation of reactive oxygen species (ROS) and a consequent decrease in photosynthetic performance. We demonstrate that a plant nanobionics approach of localizing negatively charged, sub-11 nm, spherical cerium oxide nanoparticles (nanoceria) inside chloroplasts in vivo augments ROS scavenging and photosynthesis of Arabidopsis thaliana plants under excess light (2000 μmol m -2 s -1 , 1.5 h), heat (35 °C, 2.5 h), and dark chilling (4 °C, 5 days). Poly(acrylic acid) nanoceria (PNC) with a hydrodynamic diameter (10.3 nm)-lower than the maximum plant cell wall porosity-and negative ζ-potential (-16.9 mV) exhibit significantly higher colocalization (46%) with chloroplasts in leaf mesophyll cells than aminated nanoceria (ANC) (27%) of similar size (12.6 nm) but positive charge (9.7 mV). Nanoceria are transported into chloroplasts via nonendocytic pathways, influenced by the electrochemical gradient of the plasma membrane potential. PNC with a low Ce 3+ /Ce 4+ ratio (35.0%) reduce leaf ROS levels by 52%, including hydrogen peroxide, superoxide anion, and hydroxyl radicals. For the latter ROS, there is no known plant enzyme scavenger. Plants embedded with these PNC that were exposed to abiotic stress exhibit an increase up to 19% in quantum yield of photosystem II, 67% in carbon assimilation rates, and 61% in Rubisco carboxylation rates relative to plants without nanoparticles. In contrast, PNC with high Ce 3+ /Ce 4+ ratio (60.8%) increase overall leaf ROS levels and do not protect photosynthesis from oxidative damage during abiotic stress. This study demonstrates that anionic, spherical, sub-11 nm PNC with low Ce 3+ /Ce 4+ ratio can act as a tool to study the impact of oxidative stress on plant photosynthesis and to protect plants from abiotic stress.

Magnetic studies of nickel hydride nanoparticles embedded in chitosan matrix

NASA Astrophysics Data System (ADS)

Araújo-Barbosa, S.; Morales, M. A.

2017-11-01

In this work we present a method to produce NiH (β-NiH phase) nanoparticles from Ni-Cu solid solution. The reduction of Ni2+ and Cu2+ occurred at high temperatures and in presence of glutaraldehyde, citric acid and chitosan biopolymer. The samples are mainly composed of Ni and NiH phases with particles sizes ranging from 9 to 27 nm. DC magnetization studies reveal the presence of hydrogen-poor nickel hydride phase (α-NiH phase) which enhances the saturation magnetization at temperatures below 50 K. Stability of samples stored in air after 8 months was verified, and thermal treatment at 350 oC in presence of air transformed the samples to Ni and Cu oxides. Furthermore, we present a discussion regarding the mechanism of Ni2+ and Cu2+ chemical reduction.

Optoacoustic response from graphene-based solutions embedded in optical phantoms by using 905-nm high-power diode-laser assemblies

NASA Astrophysics Data System (ADS)

Leggio, Luca; Gallego, Daniel C.; Gawali, Sandeep Babu; Dadrasnia, Ehsan; Sánchez, Miguel; Rodríguez, Sergio; González, Marta; Carpintero, Guillermo; Osiński, Marek; Lamela, Horacio

2016-03-01

During the last two decades, optoacoustic imaging has been developed as a novel biomedical imaging technique based on the generation of ultrasound waves by means of laser light. In this work, we investigate the optoacoustic response from graphene-based solutions by using a compact and cost-effective system based on an assembly of several 905-nm pulsed high-power diode lasers coupled to a bundle of 200-μm diameter- core optical fibers. The coupled light is conveyed into a lens system and focused on an absorber consisting of graphene-based nanomaterials (graphene oxide, reduced graphene oxide, and reduced graphene-oxide/gold-nanoparticle hybrid, respectively) diluted in ethanol and hosted in slightly scattering optical phantoms. The high absorption of these graphene-based solutions suggests their potential future use in optoacoustic applications as contrast agents.

Oocyte exposure to ZnO nanoparticles inhibits early embryonic development through the γ-H2AX and NF-κB signaling pathways.

PubMed

Liu, Jing; Zhao, Yong; Ge, Wei; Zhang, Pengfei; Liu, Xinqi; Zhang, Weidong; Hao, Yanan; Yu, Shuai; Li, Lan; Chu, Meiqiang; Min, Lingjiang; Zhang, Hongfu; Shen, Wei

2017-06-27

The impacts of zinc oxide nanoparticles on embryonic development following oocyte stage exposure are unknown and the underlying mechanisms are sparsely understood. In the current investigation, intact nanoparticles were detected in ovarian tissue in vivo and cultured cells in vitro under zinc oxide nanoparticles treatment. Zinc oxide nanoparticles exposure during the oocyte stage inhibited embryonic development. Notably, in vitro culture data closely matched in vivo embryonic data, in that the impairments caused by Zinc oxide nanoparticles treatment passed through cell generations; and both gamma-H2AX and NF-kappaB pathways were involved in zinc oxide nanoparticles caused embryo-toxicity. Copper oxide and silicon dioxide nanoparticles have been used to confirm that particles are important for the toxicity of zinc oxide nanoparticles. The toxic effects of zinc oxide nanoparticles emanate from both intact nanoparticles and Zn2+. Our investigation along with others suggests that zinc oxide nanoparticles are toxic to the female reproductive system [ovaries (oocytes)] and subsequently embryo-toxic and that precaution should be taken regarding human exposure to their everyday use.

Oocyte exposure to ZnO nanoparticles inhibits early embryonic development through the γ-H2AX and NF-κB signaling pathways

PubMed Central

Liu, Jing; Zhao, Yong; Ge, Wei; Zhang, Pengfei; Liu, Xinqi; Zhang, Weidong; Hao, Yanan; Yu, Shuai; Li, Lan; Chu, Meiqiang; Min, Lingjiang; Zhang, Hongfu; Shen, Wei

2017-01-01

The impacts of zinc oxide nanoparticles on embryonic development following oocyte stage exposure are unknown and the underlying mechanisms are sparsely understood. In the current investigation, intact nanoparticles were detected in ovarian tissue in vivo and cultured cells in vitro under zinc oxide nanoparticles treatment. Zinc oxide nanoparticles exposure during the oocyte stage inhibited embryonic development. Notably, in vitro culture data closely matched in vivo embryonic data, in that the impairments caused by Zinc oxide nanoparticles treatment passed through cell generations; and both gamma-H2AX and NF-kappaB pathways were involved in zinc oxide nanoparticles caused embryo-toxicity. Copper oxide and silicon dioxide nanoparticles have been used to confirm that particles are important for the toxicity of zinc oxide nanoparticles. The toxic effects of zinc oxide nanoparticles emanate from both intact nanoparticles and Zn2+. Our investigation along with others suggests that zinc oxide nanoparticles are toxic to the female reproductive system [ovaries (oocytes)] and subsequently embryo-toxic and that precaution should be taken regarding human exposure to their everyday use. PMID:28487501

The strain and thermal induced tunable charging phenomenon in low power flexible memory arrays with a gold nanoparticle monolayer

NASA Astrophysics Data System (ADS)

Zhou, Ye; Han, Su-Ting; Xu, Zong-Xiang; Roy, V. A. L.

2013-02-01

The strain and temperature dependent memory effect of organic memory transistors on plastic substrates has been investigated under ambient conditions. The gold (Au) nanoparticle monolayer was prepared and embedded in an atomic layer deposited aluminum oxide (Al2O3) as the charge trapping layer. The devices exhibited low operation voltage, reliable memory characteristics and long data retention time. Experimental analysis of the programming and erasing behavior at various bending states showed the relationship between strain and charging capacity. Thermal-induced effects on these memory devices have also been analyzed. The mobility shows ~200% rise and the memory window increases from 1.48 V to 1.8 V when the temperature rises from 20 °C to 80 °C due to thermally activated transport. The retention capability of the devices decreases with the increased working temperature. Our findings provide a better understanding of flexible organic memory transistors under various operating temperatures and validate their applications in various areas such as temperature sensors, temperature memory or advanced electronic circuits. Furthermore, the low temperature processing procedures of the key elements (Au nanoparticle monolayer and Al2O3 dielectric layer) could be potentially integrated with large area flexible electronics.The strain and temperature dependent memory effect of organic memory transistors on plastic substrates has been investigated under ambient conditions. The gold (Au) nanoparticle monolayer was prepared and embedded in an atomic layer deposited aluminum oxide (Al2O3) as the charge trapping layer. The devices exhibited low operation voltage, reliable memory characteristics and long data retention time. Experimental analysis of the programming and erasing behavior at various bending states showed the relationship between strain and charging capacity. Thermal-induced effects on these memory devices have also been analyzed. The mobility shows ~200% rise and the memory window increases from 1.48 V to 1.8 V when the temperature rises from 20 °C to 80 °C due to thermally activated transport. The retention capability of the devices decreases with the increased working temperature. Our findings provide a better understanding of flexible organic memory transistors under various operating temperatures and validate their applications in various areas such as temperature sensors, temperature memory or advanced electronic circuits. Furthermore, the low temperature processing procedures of the key elements (Au nanoparticle monolayer and Al2O3 dielectric layer) could be potentially integrated with large area flexible electronics. Electronic supplementary information (ESI) available: UV-vis spectrum of Au nanoparticle aqueous solution, transfer characteristics of the transistors without inserting an Au nanoparticle monolayer, AFM image of the pentacene layer, transfer characteristics at different program voltages and memory windows with respect to the P/E voltage. See DOI: 10.1039/c2nr32579a

Rheological behavior of clay-nanoparticle hybrid-added bentonite suspensions: specific role of hybrid additives on the gelation of clay-based fluids.

PubMed

Jung, Youngsoo; Son, You-Hwan; Lee, Jung-Kun; Phuoc, Tran X; Soong, Yee; Chyu, Minking K

2011-09-01

Two different types of clay nanoparticle hybrid, iron oxide nanoparticle clay hybrid (ICH) and Al(2)O(3)-SiO(2) nanoparticle clay hybrid (ASCH), were synthesized and their effects on the rheological properties of aqueous bentonite fluids in steady state and dynamic state were explored. When ICH particles were added, bentonite particles in the fluid cross-link to form relatively well-oriented porous structure. This is attributed to the development of positively charged edge surfaces in ICH that leads to strengthening of the gel structure of the bentonite susensions. The role of ASCH particles on the interparticle association of the bentonite fluids is different from that of ICH and sensitive to pH. As pH of ASCH-added bentonite suspensions increased, the viscosity, yield stress, storage modulus, and flow stress decreased. In contrast, at low pH, the clay suspensions containing ASCH additives were coagulated and their rheological properties become close to those of ICH added bentonite fluids. A correlation between the net surface charge of the hybrid additives and the rheological properties of the fluids indicates that the embedded nanoparticles within the interlayer space control the variable charge of the edge surfaces of the platelets and determine the particles association behavior of the clay fluids.

Tailoring the nickel nanoparticles anchored on the surface of Fe3O4@SiO2 spheres for nanocatalysis.

PubMed

Ding, Lei; Zhang, Min; Zhang, Yanwei; Yang, Jinbo; Zheng, Jing; Hayat, Tasawar; Alharbi, Njud S; Xu, Jingli

2017-08-25

Herein, we report an efficient and universal strategy for synthesizing a unique triple-shell structured Fe 3 O 4 @SiO 2 @C-Ni hybrid composite. Firstly, the Fe 3 O 4 cores were synthesized by hydrothermal reaction, and sequentially coated with SiO 2 and a thin layer of nickel-ion-doped resin-formaldehyde (RF-Ni 2+ ) using an extended Stöber method. This was followed by carbonization to produce the Fe 3 O 4 @SiO 2 @C-Ni nanocomposites with metallic nickel nanoparticles embedded in an RF-derived thin graphic carbon layer. Interestingly, the thin SiO 2 spacer layer between RF-Ni 2+ and Fe 3 O 4 plays a critical role on adjusting the size and density of the nickel nanoparticles on the surface of Fe 3 O 4 @SiO 2 nanospheres. The detailed tailoring mechanism is explicitly discussed, and it is shown that the iron oxide core can react with the nickel nanoparticles without the SiO 2 spacer layer, and the size and density of the nickel nanoparticles can be effectively controlled when the SiO 2 layer exits. The multifunctional composites exhibit a significantly enhanced catalytic performance in the reduction of 4-nitrophenol (4-NP).

Silver nanoparticle-embedded polymersome nanocarriers for the treatment of antibiotic-resistant infections

NASA Astrophysics Data System (ADS)

Geilich, Benjamin M.; van de Ven, Anne L.; Singleton, Gloria L.; Sepúlveda, Liuda J.; Sridhar, Srinivas; Webster, Thomas J.

2015-02-01

The rapidly diminishing number of effective antibiotics that can be used to treat infectious diseases and associated complications in a physician's arsenal is having a drastic impact on human health today. This study explored the development and optimization of a polymersome nanocarrier formed from a biodegradable diblock copolymer to overcome bacterial antibiotic resistance. Here, polymersomes were synthesized containing silver nanoparticles embedded in the hydrophobic compartment, and ampicillin in the hydrophilic compartment. Results showed for the first time that these silver nanoparticle-embedded polymersomes (AgPs) inhibited the growth of Escherichia coli transformed with a gene for ampicillin resistance (bla) in a dose-dependent fashion. Free ampicillin, AgPs without ampicillin, and ampicillin polymersomes without silver nanoparticles had no effect on bacterial growth. The relationship between the silver nanoparticles and ampicillin was determined to be synergistic and produced complete growth inhibition at a silver-to-ampicillin ratio of 1 : 0.64. In this manner, this study introduces a novel nanomaterial that can effectively treat problematic, antibiotic-resistant infections in an improved capacity which should be further examined for a wide range of medical applications.

Enhanced Photocatalytic Activity of Diamond Thin Films Using Embedded Ag Nanoparticles.

PubMed

Li, Shuo; Bandy, Jason A; Hamers, Robert J

2018-02-14

Silver nanoparticles embedded into the diamond thin films enhance the optical absorption and the photocatalytic activity toward the solvated electron-initiated reduction of N 2 to NH 3 in water. Here, we demonstrate the formation of diamond films with embedded Ag nanoparticles <100 nm in diameter. Cross-sectional scanning electron microscopy (SEM), energy-dependent SEM, and energy-dispersive X-ray analysis demonstrate the formation of encapsulated nanoparticles. Optical absorption measurements in the visible and ultraviolet region show that the resulting films exhibit plasmonic resonances in the visible and near-ultraviolet region. Measurements of photocatalytic activity using supraband gap (λ < 225 nm) and sub-band gap (λ > 225 nm) excitation show significantly enhanced ability to convert N 2 to NH 3 . Incorporation of Ag nanoparticles induces a nearly 5-fold increase in activity using a sub-band gap excitation with λ > 225 nm. Our results suggest that internal photoemission, in which electrons are excited from Ag into diamond's conduction band, is an important process that extends the wavelength region beyond diamond's band gap. Other factors, including Ag-induced optical scattering and formation of graphitic impurities are also discussed.

CoFe2O4-TiO2 and CoFe2O4-ZnO thin film nanostructures elaborated from colloidal chemistry and atomic layer deposition.

PubMed

Clavel, Guylhaine; Marichy, Catherine; Willinger, Marc-Georg; Ravaine, Serge; Zitoun, David; Pinna, Nicola

2010-12-07

CoFe(2)O(4)-TiO(2) and CoFe(2)O(4)-ZnO nanoparticles/film composites were prepared from directed assembly of colloidal CoFe(2)O(4) in a Langmuir-Blodgett monolayer and atomic layer deposition (ALD) of an oxide (TiO(2) or ZnO). The combination of these two methods permits the use of well-defined nanoparticles from colloidal chemistry, their assembly on a large scale, and the control over the interface between a ferrimagnetic material (CoFe(2)O(4)) and a semiconductor (TiO(2) or ZnO). Using this approach, architectures can be assembled with a precise control from the Angstrom scale (ALD) to the micrometer scale (Langmuir-Blodgett film). The resulting heterostructures present well-calibrated thicknesses. Electron microscopy and magnetic measurement studies give evidence that the size of the nanoparticles and their intrinsic magnetic properties are not altered by the various steps involved in the synthesis process. Therefore, the approach is suitable to obtain a layered composite with a quasi-monodisperse layer of ferrimagnetic nanoparticles embedded in an ultrathin film of semiconducting material.

Magnetic properties of Ni nanoparticles embedded in silica matrix (KIT-6) synthesized via novel chemical route

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dalavi, Shankar B.; Panda, Rabi N., E-mail: rnp@goa.bits-pilani.ac.in; Raja, M. Manivel

2015-06-24

Thermally stable Ni nanoparticles have been embedded in mesoporous silica matrix (KIT-6) via novel chemical reduction method by using superhydride as reducing agent. X-ray diffraction (XRD) study confirms that pure and embedded Ni nanoparticles crystallize in face centered cubic (fcc) structure. Crystallite sizes of pure Ni, 4 wt% and 8 wt% Ni in silica were estimated to be 6.0 nm, 10.4 nm and 10.5 nm, respectively. Morphology and dispersion of Ni in silica matrix were studied by scanning electron microscopy (SEM). Magnetic study shows enhancement of magnetic moments of Ni nanoparticles embedded in silica matrix compared with that of pure Ni. The resultmore » has been interpreted on the basis of size reduction and magnetic exchange effects. Saturation magnetization values for pure Ni, 4 wt% and 8 wt% Ni in silica were found to be 15.77 emu/g, 5.08 emu/g and 2.00 emu/g whereas coercivity values were 33.72 Oe, 92.47 Oe and 64.70 Oe, respectively. We anticipate that the observed magnetic properties may find application as soft magnetic materials.« less

Preparation and characterization of nanocomposite polyvinyl chloride films with NO-generating activity

NASA Astrophysics Data System (ADS)

Kozakevych, Roman B.; Korobeinyk, Alina V.; Bolbukh, Yulia M.; Tertykh, Valentin A.; Mikhalovska, Lyuba I.; Zienkiewicz-Strzałka, Malgorzlata; Deryło-Marczewska, Anna

2018-03-01

The silica and copper oxide nanoparticles were embedded into the polyvinyl chloride film and obtained filled composites were tested as a catalyst in the reaction of the NO release from appropriate biomolecules. Obtained materials were characterized using scanning electron, atomic-force microscopies and thermomechanical analysis. It has been shown that the introduced particles are distributed uniformly in the polymeric matrix of hybrid composite and such film produces a significant amount of NO when reacts with S-nitrosothiols. At the same time, the unfilled polyvinyl chloride film had no statistically significant catalytic activity.

Size-Dependent Surface Energy Density of Spherical Face-Centered-Cubic Metallic Nanoparticles.

PubMed

Wei, Yaochi; Chen, Shaohua

2015-12-01

The surface energy density of nano-sized elements exhibits a significantly size-dependent behavior. Spherical nanoparticle, as an important element in nano-devices and nano-composites, has attracted many interesting studies on size effect, most of which are molecular dynamics (MD) simulations. However, the existing MD calculations yield two opposite size-dependent trends of surface energy density of nanoparticles. In order to clarify such a real underlying problem, atomistic calculations are carried out in the present paper for various spherical face-centered-cubic (fcc) metallic nanoparticles. Both the embedded atom method (EAM) potential and the modified embedded atom method (MEAM) one are adopted. It is found that the size-dependent trend of surface energy density of nanoparticles is not governed by the chosen potential function or variation trend of surface energy, but by the defined radius of spherical nanoparticles in MD models. The finding in the present paper should be helpful for further theoretical studies on surface/interface effect of nanoparticles and nanoparticle-reinforced composites.

Modeling Nanoparticle Wrapping or Translocation in Bilayer Membranes

PubMed Central

Curtis, Emily M.; Bahrami, Amir H.; Weikl, Thomas R.; Hall, Carol K.

2015-01-01

The spontaneous wrapping of nanoparticles by membranes is of increasing interest as nanoparticles become more prevalent in consumer products and hence more likely to enter the human body. We introduce a simulations-based tool that can be used to visualize the molecular level interaction between nanoparticles and bilayer membranes. By combining LIME, an intermediate resolution, implicit solvent model for phospholipids, with discontinuous molecular dynamics (DMD), we are able to simulate the wrapping or embedding of nanoparticles by 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) bilayer membranes. Simulations of hydrophilic nanoparticles with diameters from 10Å to 250Å show that hydrophilic nanoparticles with diameters greater than 20Å become wrapped while the nanoparticle with a diameter of 10Å does not . Instead this smaller particle became embedded in the bilayer surface where it could interact with the hydrophilic head groups of the lipid molecules. We also investigate the interaction between a DPPC bilayer and hydrophobic nanoparticles with diameters 10Å to 40Å. These nanoparticles do not undergo the wrapping process; instead they directly penetrate the membrane and embed themselves within the inner hydrophobic core of the bilayers. PMID:26260123

Oxide nanoparticles in an Al-alloyed oxide dispersion strengthened steel: crystallographic structure and interface with ferrite matrix

NASA Astrophysics Data System (ADS)

Zhang, Zhenbo; Pantleon, Wolfgang

2017-07-01

Oxide nanoparticles are quintessential for ensuring the extraordinary properties of oxide dispersion strengthened (ODS) steels. In this study, the crystallographic structure of oxide nanoparticles, and their interface with the ferritic steel matrix in an Al-alloyed ODS steel, i.e. PM2000, were systematically investigated by high-resolution transmission electron microscopy. The majority of oxide nanoparticles were identified to be orthorhombic YAlO3. During hot consolidation and extrusion, they develop a coherent interface and a near cuboid-on-cube orientation relationship with the ferrite matrix in the material. After annealing at 1200 °C for 1 h, however, the orientation relationship between the oxide nanoparticles and the matrix becomes arbitrary, and their interface mostly incoherent. Annealing at 1300 °C leads to considerable coarsening of oxide nanoparticles, and a new orientation relationship of pseudo-cube-on-cube between oxide nanoparticles and ferrite matrix develops. The reason for the developing interfaces and orientation relationships between oxide nanoparticles and ferrite matrix under different conditions is discussed.

Facile preparation of Ni nanowire embedded nitrogen and sulfur dual-doped carbon nanofibers and its superior catalytic activity toward urea oxidation.

PubMed

Liu, Dong; Li, Wenjia; Li, Libo; Ling, Hao; You, Tianyan

2018-06-08

A novel hairy-shaped Ni nanowire embedded nitrogen and sulfur dual-doped carbon nanofibers (Ni/N,S-CNFs) with superior electrocatalytic properties for urea oxidation reaction (UOR) was reported. The Ni/N,S-CNFs was prepared by electrospinning and carbonization process, using melamine-trithiocyanuric acid (MTCA) aggregates as both the N and S element sources. Noteworthy, MTCA also favored the formation of Ni nanowire via vapor liquid-solid mechanism, while Ni nanoparticles loaded CNFs (Ni/CNFs) was obtained without MTCA. For UOR tests, a high peak current intensity of 37.0 mA mg -1 was obtained on Ni/N,S-CNFs at 0.42 V (vs. SCE), 2-times higher of that on Ni/CNFs. Besides, the catalytic stability of Ni/N,S-CNFs was also improved. The enhanced catalytic properties of Ni/N,S-CNFs for UOR were ascribed to its unique Ni nanowires structure as well as the N, S dual-doping. Our work reveals that the property improvement of metal-based catalysts could be achieved by the heteroatom doping to fine the metal nanostructure. Copyright © 2018. Published by Elsevier Inc.

Formation of porous silicon oxide from substrate-bound silicon rich silicon oxide layers by continuous-wave laser irradiation

NASA Astrophysics Data System (ADS)

Wang, Nan; Fricke-Begemann, Th.; Peretzki, P.; Ihlemann, J.; Seibt, M.

2018-03-01

Silicon nanocrystals embedded in silicon oxide that show room temperature photoluminescence (PL) have great potential in silicon light emission applications. Nanocrystalline silicon particle formation by laser irradiation has the unique advantage of spatially controlled heating, which is compatible with modern silicon micro-fabrication technology. In this paper, we employ continuous wave laser irradiation to decompose substrate-bound silicon-rich silicon oxide films into crystalline silicon particles and silicon dioxide. The resulting microstructure is studied using transmission electron microscopy techniques with considerable emphasis on the formation and properties of laser damaged regions which typically quench room temperature PL from the nanoparticles. It is shown that such regions consist of an amorphous matrix with a composition similar to silicon dioxide which contains some nanometric silicon particles in addition to pores. A mechanism referred to as "selective silicon ablation" is proposed which consistently explains the experimental observations. Implications for the damage-free laser decomposition of silicon-rich silicon oxides and also for controlled production of porous silicon dioxide films are discussed.

Method for preparing hydrous iron oxide gels and spherules

DOEpatents

Collins, Jack L.; Lauf, Robert J.; Anderson, Kimberly K.

2003-07-29

The present invention is directed to methods for preparing hydrous iron oxide spherules, hydrous iron oxide gels such as gel slabs, films, capillary and electrophoresis gels, iron monohydrogen phosphate spherules, hydrous iron oxide spherules having suspendable particles homogeneously embedded within to form composite sorbents and catalysts, iron monohydrogen phosphate spherules having suspendable particles of at least one different sorbent homogeneously embedded within to form a composite sorbent, iron oxide spherules having suspendable particles homogeneously embedded within to form a composite of hydrous iron oxide fiber materials, iron oxide fiber materials, hydrous iron oxide fiber materials having suspendable particles homogeneously embedded within to form a composite, iron oxide fiber materials having suspendable particles homogeneously embedded within to form a composite, dielectric spherules of barium, strontium, and lead ferrites and mixtures thereof, and composite catalytic spherules of barium or strontium ferrite embedded with oxides of Mg, Zn, Pb, Ce and mixtures thereof. These variations of hydrous iron oxide spherules and gel forms prepared by the gel-sphere, internal gelation process offer more useful forms of inorganic ion exchangers, catalysts, getters, dielectrics, and ceramics.

Three-dimensional calibration targets for optical coherence tomography

NASA Astrophysics Data System (ADS)

Gabriele Sandrian, Michelle; Tomlins, Pete; Woolliams, Peter; Rasakanthan, Janarthanan; Lee, Graham C.; Yang, Anna; Považay, Boris; Alex, Aneesh; Sugden, Kate; Drexler, Wolfgang

2012-03-01

The recent expansion of clinical applications for optical coherence tomography (OCT) is driving the development of approaches for consistent image acquisition. There is a simultaneous need for time-stable, easy-to-use imaging targets for calibration and standardization of OCT devices. We present calibration targets consisting of three-dimensional structures etched into nanoparticle-embedded resin. Spherical iron oxide nanoparticles with a predominant particle diameter of 400 nm were homogeneously dispersed in a two part polyurethane resin and allowed to harden overnight. These samples were then etched using a precision micromachining femtosecond laser with a center wavelength of 1026 nm, 100kHz repetition rate and 450 fs pulse duration. A series of lines in depth were etched, varying the percentage of inscription energy and speed of the translation stage moving the target with respect to the laser. Samples were imaged with a dual wavelength spectral-domain OCT system (λ=800nm, ▵λ~180nm, and λ=1325nm, ▵λ~100nm) and point-spread function of nanoparticles within the target was measured.

Bendable solid-state supercapacitors with Au nanoparticle-embedded graphene hydrogel films

PubMed Central

Yang, Kyungwhan; Cho, Kyoungah; Yoon, Dae Sung; Kim, Sangsig

2017-01-01

In this study, we fabricate bendable solid-state supercapacitors with Au nanoparticle (NP)-embedded graphene hydrogel (GH) electrodes and investigate the influence of the Au NP embedment on the internal resistance and capacitive performance. Embedding the Au NPs into the GH electrodes results in a decrease of the internal resistance from 35 to 21 Ω, and a threefold reduction of the IR drop at a current density of 5 A/g when compared with GH electrodes without Au NPs. The Au NP-embedded GH supercapacitors (NP-GH SCs) exhibit excellent capacitive performances, with large specific capacitance (135 F/g) and high energy density (15.2 W·h/kg). Moreover, the NP-GH SCs exhibit comparable areal capacitance (168 mF/cm2) and operate under tensile/compressive bending. PMID:28074865

Biogenic copper oxide nanoparticles synthesis using Tabernaemontana divaricate leaf extract and its antibacterial activity against urinary tract pathogen

NASA Astrophysics Data System (ADS)

Sivaraj, Rajeshwari; Rahman, Pattanathu K. S. M.; Rajiv, P.; Salam, Hasna Abdul; Venckatesh, R.

2014-12-01

This investigation explains the biosynthesis and characterization of copper oxide nanoparticles from an Indian medicinal plant by an eco-friendly method. The main objective of this study is to synthesize copper oxide nanoparticles from Tabernaemontana divaricate leaves through a green chemistry approach. Highly stable, spherical copper oxide nanoparticles were synthesized by using 50% concentration of Tabernaemontana leaf extract. Formation of copper oxide nanoparticles have been characterized by UV-Vis absorption spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDX) and transmission electron microscopy (TEM) analysis. All the analyses revealed that copper oxide nanoparticles were 48 ± 4 nm in size. Functional groups and chemical composition of copper oxide were also confirmed. Antimicrobial activity of biogenic copper oxide nanoparticles were investigated and maximum zone of inhibition was found in 50 μg/ml copper oxide nanoparticles against urinary tract pathogen (Escherichia coli).

Method for preparing hydrous zirconium oxide gels and spherules

DOEpatents

Collins, Jack L.

2003-08-05

Methods for preparing hydrous zirconium oxide spherules, hydrous zirconium oxide gels such as gel slabs, films, capillary and electrophoresis gels, zirconium monohydrogen phosphate spherules, hydrous zirconium oxide spherules having suspendable particles homogeneously embedded within to form a composite sorbent, zirconium monohydrogen phosphate spherules having suspendable particles of at least one different sorbent homogeneously embedded within to form a composite sorbent having a desired crystallinity, zirconium oxide spherules having suspendable particles homogeneously embedded within to form a composite, hydrous zirconium oxide fiber materials, zirconium oxide fiber materials, hydrous zirconium oxide fiber materials having suspendable particles homogeneously embedded within to form a composite, zirconium oxide fiber materials having suspendable particles homogeneously embedded within to form a composite and spherules of barium zirconate. The hydrous zirconium oxide spherules and gel forms prepared by the gel-sphere, internal gelation process are useful as inorganic ion exchangers, catalysts, getters and ceramics.

Transition-metal-ion-mediated polymerization of dopamine: mussel-inspired approach for the facile synthesis of robust transition-metal nanoparticle-graphene hybrids.

PubMed

Yang, Liping; Kong, Junhua; Zhou, Dan; Ang, Jia Ming; Phua, Si Lei; Yee, Wu Aik; Liu, Hai; Huang, Yizhong; Lu, Xuehong

2014-06-16

Inspired by the high transition-metal-ion content in mussel glues, and the cross-linking and mechanical reinforcement effects of some transition-metal ions in mussel threads, high concentrations of nickel(II), cobalt(II), and manganese(II) ions have been purposely introduced into the reaction system for dopamine polymerization. Kinetics studies were conducted for the Ni(2+)-dopamine system to investigate the polymerization mechanism. The results show that the Ni(2+) ions could accelerate the assembly of dopamine oligomers in the polymerization process. Spectroscopic and electron microscopic studies reveal that the Ni(2+) ions are chelated with polydopamine (PDA) units, forming homogeneous Ni(2+)-PDA complexes. This facile one-pot approach is utilized to construct transition-metal-ion-PDA complex thin coatings on graphene oxide, which can be carbonized to produce robust hybrid nanosheets with well-dispersed metallic nickel/metallic cobalt/manganese(II) oxide nanoparticles embedded in PDA-derived thin graphitic carbon layers. The nickel-graphene hybrid prepared by using this approach shows good catalytic properties and recyclability for the reduction of p-nitrophenol. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ultrafine Pt Nanoparticles and Amorphous Nickel Supported on 3D Mesoporous Carbon Derived from Cu-Metal-Organic Framework for Efficient Methanol Oxidation and Nitrophenol Reduction.

PubMed

Wu, Xue-Qian; Zhao, Jun; Wu, Ya-Pan; Dong, Wen-Wen; Li, Dong-Sheng; Li, Jian-Rong; Zhang, Qichun

2018-04-18

The development of novel strategy to produce new porous carbon materials is extremely important because these materials have wide applications in energy storage/conversion, mixture separation, and catalysis. Herein, for the first time, a novel 3D carbon substrate with hierarchical pores derived from commercially available Cu-MOF (metal-organic framework) (HKUST-1) through carbonization and chemical etching has been employed as the catalysts' support. Highly dispersed Pt nanoparticles and amorphous nickel were evenly dispersed on the surface or embedded within carbon matrix. The corresponding optimal composite catalyst exhibits a high mass-specific peak current of 1195 mA mg -1 Pt and excellent poison resistance capacity ( I F / I B = 1.58) for methanol oxidation compared to commercial Pt/C (20%). Moreover, both composite catalysts manifest outstanding properties in the reduction of nitrophenol and demonstrate diverse selectivities for 2/3/4-nitrophenol, which can be attributed to different integrated forms between active species and carbon matrix. This attractive route offers broad prospects for the usage of a large number of available MOFs in fabricating functional carbon materials as well as highly active carbon-based electrocatalysts and heterogeneous organic catalysts.

A colorimetric assay for measuring iodide using Au@Ag core-shell nanoparticles coupled with Cu(2+).

PubMed

Zeng, Jingbin; Cao, Yingying; Lu, Chun-Hua; Wang, Xu-Dong; Wang, Qianru; Wen, Cong-Ying; Qu, Jian-Bo; Yuan, Cunguang; Yan, Zi-Feng; Chen, Xi

2015-09-03

Au@Ag core-shell nanoparticles (NPs) were synthesized and coupled with copper ion (Cu(2+)) for the colorimetric sensing of iodide ion (I(-)). This assay relies on the fact that the absorption spectra and the color of metallic core-shell NPs are sensitive to their chemical ingredient and dimensional core-to-shell ratio. When I(-) was added to the Au@Ag core-shell NPs-Cu(2+) system/solution, Cu(2+) can oxidize I(-) into iodine (I2), which can further oxidize silver shells to form silver iodide (AgI). The generated Au@AgI core-shell NPs led to color changes from yellow to purple, which was utilized for the colorimetric sensing of I(-). The assay only took 10 min with a lowest detectable concentration of 0.5 μM, and it exhibited excellent selectivity for I(-) over other common anions tested. Furthermore, Au@Ag core-shell NPs-Cu(2+) was embedded into agarose gels as inexpensive and portable "test strips", which were successfully used for the semi-quantitation of I(-) in dried kelps. Copyright © 2015 Elsevier B.V. All rights reserved.

Simulation of magnetic active polymers for versatile microfluidic devices

NASA Astrophysics Data System (ADS)

Gusenbauer, Markus; Özelt, Harald; Fischbacher, Johann; Reichel, Franz; Exl, Lukas; Bance, Simon; Kataeva, Nadezhda; Binder, Claudia; Brückl, Hubert; Schrefl, Thomas

2013-01-01

We propose to use a compound of magnetic nanoparticles (20-100 nm) embedded in a flexible polymer (Polydimethylsiloxane PDMS) to filter circulating tumor cells (CTCs). The analysis of CTCs is an emerging tool for cancer biology research and clinical cancer management including the detection, diagnosis and monitoring of cancer. The combination of experiments and simulations lead to a versatile microfluidic lab-on-chip device. Simulations are essential to understand the influence of the embedded nanoparticles in the elastic PDMS when applying a magnetic gradient field. It combines finite element calculations of the polymer, magnetic simulations of the embedded nanoparticles and the fluid dynamic calculations of blood plasma and blood cells. With the use of magnetic active polymers a wide range of tunable microfluidic structures can be created. The method can help to increase the yield of needed isolated CTCs.

Temperature Response of Rhodamine B-Doped Latex Particles. From Solution to Single Particles.

PubMed

Soleilhac, Antonin; Girod, Marion; Dugourd, Philippe; Burdin, Béatrice; Parvole, Julien; Dugas, Pierre-Yves; Bayard, François; Lacôte, Emmanuel; Bourgeat-Lami, Elodie; Antoine, Rodolphe

2016-04-26

Nanoparticle-based temperature imaging is an emerging field of advanced applications. Herein, the sensitivity of the fluorescence of rhodamine B-doped latex nanoparticles toward temperature is described. Submicrometer size latex particles were prepared by a surfactant-free emulsion polymerization method that allowed a simple and inexpensive way to incorporate rhodamine B into the nanoparticles. Also, rhodamine B-coated latex nanoparticles dispersed in water were prepared in order to address the effect of the dye location in the nanoparticles on their temperature dependence. A better linearity of the temperature dependence emission of the rhodamine B-embedded latex particles, as compared to that of free rhodamine B dyes or rhodamine B-coated latex particles, is observed. Temperature-dependent fluorescence measurements by fluorescent confocal microscopy on individual rhodamine B-embedded latex particles were found similar to those obtained for fluorescent latex nanoparticles in solution, indicating that these nanoparticles could be good candidates to probe thermal processes as nanothermometers.

Properties of Au/Copper oxide nanocomposite prepared by green laser irradiation of the mixture of individual suspensions

NASA Astrophysics Data System (ADS)

Aazadfar, Parvaneh; Solati, Elmira; Dorranian, Davoud

2018-04-01

The fundamental wavelength of a Q-switched pulsed Nd:YAG laser was employed to produce Au and copper oxide nanoparticles via pulsed laser ablation method in water. Different volumetric ratio of nanoparticles were mixed and irradiated by the second harmonic pulses of the Nd:YAG laser to prepare Au/Copper oxide nanocomposite. The experimental investigation was dedicated to study the properties of Au/Copper oxide nanocomposite as a function of volumetric ratio of Au nanoparticles and copper oxide nanoparticles. Nanocomposites of Au and copper oxide were found almost spherical in shape. Adhesion of spherical nanostructure in Au/Copper oxide nanocomposites was decreased with increasing the concentration of Au nanoparticles. Crystalline phase of the Au/Copper oxide nanocomposites differs with the change in the volumetric ratio of Au and copper oxide nanoparticles. The intensity of surface plasmon resonance of Au nanoparticles was decreased after irradiation. Au/Copper oxide nanocomposites suspensions have emissions in the visible range. Results reveal that green laser irradiation of nanoparticle suspensions is an appropriate method to synthesize Au based nanocomposites with controlled composition and size.

In situ TEM study of lithiation behavior of silicon nanoparticles attached to and embedded in a carbon matrix.

PubMed

Gu, Meng; Li, Ying; Li, Xiaolin; Hu, Shenyang; Zhang, Xiangwu; Xu, Wu; Thevuthasan, Suntharampillai; Baer, Donald R; Zhang, Ji-Guang; Liu, Jun; Wang, Chongmin

2012-09-25

Rational design of silicon and carbon nanocomposite with a special topological feature has been demonstrated to be a feasible way for mitigating the capacity fading associated with the large volume change of silicon anode in lithium ion batteries. Although the lithiation behavior of silicon and carbon as individual components has been well understood, lithium ion transport behavior across a network of silicon and carbon is still lacking. In this paper, we probe the lithiation behavior of silicon nanoparticles attached to and embedded in a carbon nanofiber using in situ TEM and continuum mechanical calculation. We found that aggregated silicon nanoparticles show contact flattening upon initial lithiation, which is characteristically analogous to the classic sintering of powder particles by a neck-growth mechanism. As compared with the surface-attached silicon particles, particles embedded in the carbon matrix show delayed lithiation. Depending on the strength of the carbon matrix, lithiation of the embedded silicon nanoparticles can lead to the fracture of the carbon fiber. These observations provide insights on lithium ion transport in the network-structured composite of silicon and carbon and ultimately provide fundamental guidance for mitigating the failure of batteries due to the large volume change of silicon anodes.

Carrier transport mechanisms of nonvolatile write-once-read-many-times memory devices with InP-ZnS core-shell nanoparticles embedded in a polymethyl methacrylate layer

NASA Astrophysics Data System (ADS)

Ham, Jung Hoon; Oh, Do Hyun; Cho, Sung Hwan; Jung, Jae Hun; Kim, Tae Whan; Ryu, Eui Dock; Kim, Sang Wook

2009-03-01

Current-voltage (I-V) curves at 300 K for Al/InP-ZnS nanoparticles embedded in a polymethyl methacrylate layer/Al devices showed electrical bistability for write-once-read-many-times (WORM) memory devices. From the I-V curves, the ON/OFF ratio for the device with InP-ZnS nanoparticles was significantly larger than that for the device without InP-ZnS nanoparticles, indicative of the existence of charge capture in the InP nanoparticles. The estimated retention time of the ON state for the WORM memory device was more than 10 years. The carrier transport mechanisms for the WORM memory devices are described by using several models to fit the experimental I-V data.

High-performance liquid chromatography separation of unsaturated organic compounds by a monolithic silica column embedded with silver nanoparticles.

PubMed

Zhu, Yang; Morisato, Kei; Hasegawa, George; Moitra, Nirmalya; Kiyomura, Tsutomu; Kurata, Hiroki; Kanamori, Kazuyoshi; Nakanishi, Kazuki

2015-08-01

The optimization of a porous structure to ensure good separation performances is always a significant issue in high-performance liquid chromatography column design. Recently we reported the homogeneous embedment of Ag nanoparticles in periodic mesoporous silica monolith and the application of such Ag nanoparticles embedded silica monolith for the high-performance liquid chromatography separation of polyaromatic hydrocarbons. However, the separation performance remains to be improved and the retention mechanism as compared with the Ag ion high-performance liquid chromatography technique still needs to be clarified. In this research, Ag nanoparticles were introduced into a macro/mesoporous silica monolith with optimized pore parameters for high-performance liquid chromatography separations. Baseline separation of benzene, naphthalene, anthracene, and pyrene was achieved with the theoretical plate number for analyte naphthalene as 36,000 m(-1). Its separation function was further extended to cis/trans isomers of aromatic compounds where cis/trans stilbenes were chosen as a benchmark. Good separation of cis/trans-stilbene with separation factor as 7 and theoretical plate number as 76,000 m(-1) for cis-stilbene was obtained. The trans isomer, however, is retained more strongly, which contradicts the long- established retention rule of Ag ion chromatography. Such behavior of Ag nanoparticles embedded in a silica column can be attributed to the differences in the molecular geometric configuration of cis/trans stilbenes. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Efficient One-Pot Synthesis of Colloidal Zirconium Oxide Nanoparticles for High-Refractive-Index Nanocomposites.

PubMed

Liu, Chao; Hajagos, Tibor Jacob; Chen, Dustin; Chen, Yi; Kishpaugh, David; Pei, Qibing

2016-02-01

Zirconium oxide nanoparticles are promising candidates for optical engineering, photocatalysis, and high-κ dielectrics. However, reported synthetic methods for the colloidal zirconium oxide nanoparticles use unstable alkoxide precursors and have various other drawbacks, limiting their wide application. Here, we report a facile one-pot method for the synthesis of colloidally stable zirconium oxide nanoparticles. Using a simple solution of zirconium trifluoroacetate in oleylamine, highly stable zirconium oxide nanoparticles have been synthesized with high yield, following a proposed amidization-assisted sol-gel mechanism. The nanoparticles can be readily dispersed in nonpolar solvents, forming a long-term stable transparent solution, which can be further used to fabricate high-refractive-index nanocomposites in both monolith and thin-film forms. In addition, the same method has also been extended to the synthesis of titanium oxide nanoparticles, demonstrating its general applicability to all group IVB metal oxide nanoparticles.

Positronic probe of vacancy defects on surfaces of Au nanoparticles embedded in MgO

NASA Astrophysics Data System (ADS)

Xu, Jun; Moxom, J.; Somieski, B.; White, C. W.; Mills, A. P., Jr.; Suzuki, R.; Ishibashi, S.

2001-09-01

Clusters of four atomic vacancies were found in Au nanoparticle-embedded MgO by positron lifetime spectroscopy [Phys. Rev. Lett. 83, 4586 (1999)]. These clusters were also suggested to locate at the surface of Au nanoparticles by one-detector measurements of Doppler broadening of annihilation radiation. In this work we provide evidence, using two-detector coincidence experiments of Doppler broadening (2D-DBAR), to clarify that these vacancy clusters reside on the surfaces of Au nanoparticles. This work also demonstrates a method for identifying defects at nanomaterials interfaces: a combination of both positron lifetime spectroscopy, which tells the type of the defects, and 2D-DBAR measurements, which reveals chemical environment of the defects.

Zinc oxide nanoparticles decrease the expression and activity of plasma membrane calcium ATPase, disrupt the intracellular calcium homeostasis in rat retinal ganglion cells.

PubMed

Guo, Dadong; Bi, Hongsheng; Wang, Daoguang; Wu, Qiuxin

2013-08-01

Zinc oxide nanoparticle is one of the most important materials with diverse applications. However, it has been reported that zinc oxide nanoparticles are toxic to organisms, and that oxidative stress is often hypothesized to be an important factor in cytotoxicity mediated by zinc oxide nanoparticles. Nevertheless, the mechanism of toxicity of zinc oxide nanoparticles has not been completely understood. In this study, we investigated the cytotoxic effect of zinc oxide nanoparticles and the possible molecular mechanism involved in calcium homeostasis mediated by plasma membrane calcium ATPase in rat retinal ganglion cells. Real-time cell electronic sensing assay showed that zinc oxide nanoparticles could exert cytotoxic effect on rat retinal ganglion cells in a concentration-dependent manner; flow cytometric analysis indicated that zinc oxide nanoparticles could lead to cell damage by inducing the overproduction of reactive oxygen species. Furthermore, zinc oxide nanoparticles could also apparently decrease the expression level and their activity of plasma membrane calcium ATPase, which finally disrupt the intracellular calcium homeostasis and result in cell death. Taken together, zinc oxide nanoparticles could apparently decrease the plasma membrane calcium ATPase expression, inhibit their activity, cause the elevated intracellular calcium ion level and disrupt the intracellular calcium homeostasis. Further, the disrupted calcium homeostasis will trigger mitochondrial dysfunction, generate excessive reactive oxygen species, and finally initiate cell death. Thus, the disrupted calcium homeostasis is involved in the zinc oxide nanoparticle-induced rat retinal ganglion cell death. Copyright © 2013 Elsevier Ltd. All rights reserved.

Enhanced Column Filtration for Arsenic Removal from Water: Polymer-Templated Iron Oxide Nanoparticles Immobilized on Sand via Layer-by-Layer Deposition

NASA Astrophysics Data System (ADS)

Cheng, Calvin Chia-Hung

Arsenic is ubiquitous in water sources around the world and is highly toxic. While precipitation and membrane filtration techniques are successfully implemented in developed cities, they are unsuitable for rural and low-resource settings lacking centralized facilities. This thesis presents the use of ultra-small iron oxide (Fe2O3) nanoparticles functionalized on sand granules for use as a house-hold scale adsorption filter. Water-stable alpha-Fe2O3 (hematite) nanoparticles (<10 nm) were synthesized via a collapsed-polymer approach using poly(acrylic acid) and Fe3+ ions. The nanoparticles exhibited high arsenic adsorption, with 147 +/- 2 mg As(III) per g Fe2O3 and 91 +/- 10 mg As(V) per g Fe2O3. The platform was also used to synthesize iron-based composites, including magnetite (Fe 3O4) and Fe-Cu oxide nanoparticles. For use as a column filter, Fe2O3-PAA nanoparticles were functionalized on sand granules using a layer-by-layer deposition method, with the nanoparticles embedded in the negative layer. The removal of As(III) by the Fe2O 3-PAA functionalized column was described by reversible 1st order kinetics where the forward and reverse rate constants were 0.31 hr -1 and 0.097 hr-1, respectively. Implemented as a passive water filter with 30 x 30 x 50 cm3 dimensions, the filter has an expected lifetime in the order of many years. By controlling the flow rate of the column depending on contamination levels, the filter effectively removes arsenic down to the safety limit of 0.01 mg/L. In a parallel project, the layer-by-layer deposition of Poly(diallydimethyl ammonium chloride) (PDDA) and poly(sodium 5-styrenesulfonate) (PSS) was exploited for a highly practical synthesis of discrete gradient surfaces. By independently controlling the concentration of NaCl in PDDA and PSS deposition solutions, a 2-dimensional matrix of surfaces was created in 96-well microtiter plates. Distinct non-monotonic dye adsorption patterns on the gradient surfaces was observed. Practical knowledge from this project was also used to enhance the nanoparticle surface functionalization described above. In all, a practical, no expertise-needed passive water filtration unit was described in this thesis. The unit makes use of hardware available in existing sand-based water filters, and is designed to address the unmet need of arsenic removal from drinking water in low-resource or rural settings.

The detection of HBV DNA with gold-coated iron oxide nanoparticle gene probes

NASA Astrophysics Data System (ADS)

Xi, Dong; Luo, XiaoPing; Lu, QiangHua; Yao, KaiLun; Liu, ZuLi; Ning, Qin

2008-03-01

Gold-coated iron oxide nanoparticle Hepatitis B virus (HBV) DNA probes were prepared, and their application for HBV DNA measurement was studied. Gold-coated iron oxide nanoparticles were prepared by the citrate reduction of tetra-chloroauric acid in the presence of iron oxide nanoparticles which were added as seeds. With a fluorescence-based method, the maximal surface coverage of hexaethiol 30-mer oligonucleotides and the maximal percentage of hybridization strands on gold-coated iron oxide nanoparticles were (120 ± 8) oligonucleotides per nanoparticle, and (14 ± 2%), respectively, which were comparable with those of (132 ± 10) and (22 ± 3%) in Au nanoparticle groups. Large network aggregates were formed when gold-coated iron oxide nanoparticle HBV DNA gene probe was applied to detect HBV DNA molecules as evidenced by transmission electron microscopy and the high specificity was verified by blot hybridization. Our results further suggested that detecting DNA with iron oxide nanoparticles and magnetic separator was feasible and might be an alternative effective method.

Synthesis of Lithium Metal Oxide Nanoparticles by Induction Thermal Plasmas.

PubMed

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

2016-04-06

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.

Method for preparing hydrous titanium oxide spherules and other gel forms thereof

DOEpatents

Collins, J.L.

1998-10-13

The present invention are methods for preparing hydrous titanium oxide spherules, hydrous titanium oxide gels such as gel slabs, films, capillary and electrophoresis gels, titanium monohydrogen phosphate spherules, hydrous titanium oxide spherules having suspendible particles homogeneously embedded within to form a composite sorbent, titanium monohydrogen phosphate spherules having suspendible particles of at least one different sorbent homogeneously embedded within to form a composite sorbent having a desired crystallinity, titanium oxide spherules in the form of anatase, brookite or rutile, titanium oxide spherules having suspendible particles homogeneously embedded within to form a composite, hydrous titanium oxide fiber materials, titanium oxide fiber materials, hydrous titanium oxide fiber materials having suspendible particles homogeneously embedded within to form a composite, titanium oxide fiber materials having suspendible particles homogeneously embedded within to form a composite and spherules of barium titanate. These variations of hydrous titanium oxide spherules and gel forms prepared by the gel-sphere, internal gelation process offer more useful forms of inorganic ion exchangers, catalysts, getters and ceramics. 6 figs.

Method for preparing hydrous titanium oxide spherules and other gel forms thereof

DOEpatents

Collins, Jack L.

1998-01-01

The present invention are methods for preparing hydrous titanium oxide spherules, hydrous titanium oxide gels such as gel slabs, films, capillary and electrophoresis gels, titanium monohydrogen phosphate spherules, hydrous titanium oxide spherules having suspendible particles homogeneously embedded within to form a composite sorbent, titanium monohydrogen phosphate spherules having suspendible particles of at least one different sorbent homogeneously embedded within to form a composite sorbent having a desired crystallinity, titanium oxide spherules in the form of anatase, brookite or rutile, titanium oxide spherules having suspendible particles homogeneously embedded within to form a composite, hydrous titanium oxide fiber materials, titanium oxide fiber materials, hydrous titanium oxide fiber materials having suspendible particles homogeneously embedded within to form a composite, titanium oxide fiber materials having suspendible particles homogeneously embedded within to form a composite and spherules of barium titanate. These variations of hydrous titanium oxide spherules and gel forms prepared by the gel-sphere, internal gelation process offer more useful forms of inorganic ion exchangers, catalysts, getters and ceramics.

In situ synthesis of ultra-fine, porous, tin oxide-carbon nanocomposites via a molten salt method for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Liu, Bin; Guo, Zai Ping; Du, Guodong; Nuli, Yanna; Hassan, Mohd Faiz; Jia, Dianzeng

Ultra-fine, porous, tin oxide-carbon (SnO 2/C) nanocomposites are fabricated by a molten salt method at 300 °C, and malic acid is decomposed as the carbon source. In situ synthesis is favourable for the combination of carbon and SnO 2. The structure and morphology are confirmed by X-ray diffraction analysis, specific surface-area measurements, and transmission electron microscopy (TEM). Examination of TEM images reveals that the SnO 2 nanoparticles are embedded in the carbon matrix, with sizes between 2 and 5 nm. The electrochemical measurements show that the nanocomposite delivers a high capacity with good capacity retention as an anode material for lithium-ion batteries, due to the combination of the ultra-fine porous structure and the carbon component.

Pulsed Laser Synthesized Magnetic Cobalt Oxide Nanoparticles for Biomedical Applications

NASA Astrophysics Data System (ADS)

Bhatta, Hari; Gupta, Ram; Ghosh, Kartik; Kahol, Pawan; Delong, Robert; Wanekawa, Adam

2011-03-01

Nanomaterials research has become a major attraction in the field of advanced materials research in the area of Physics, Chemistry, and Materials Science. Biocompatible and chemically stable magnetic metal oxide nanoparticles have biomedical applications that includes drug delivery, cell and DNA separation, gene cloning, magnetic resonance imaging (MRI). This research is aimed at the fabrication of magnetic cobalt oxide nanoparticles using a safe, cost effective, and easy to handle technique that is capable of producing nanoparticles free of any contamination. Cobalt oxide nanoparticles have been synthesized at room temperature using cobalt foil by pulsed laser ablation technique. These cobalt oxide nanoparticles were characterized using UV-Visible (UV-Vis) spectroscopy, transmission electron microscopy (TEM), and dynamic laser light scattering (DLLS). The magnetic cobalt oxides nanoparticles were stabilized in glucose solutions of various concentrations in deionized water. The presence of UV-Vis absorption peak at 270 nm validates the nature of cobalt oxide nanoparticles. The DLLS size distributions of nanoparticles are in the range of 110 to 300 nm, which further confirms the presence nanoparticles. This work is partially supported by National Science Foundation (DMR- 0907037).

Shape-dependent bactericidal activity of copper oxide nanoparticle mediated by DNA and membrane damage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Laha, Dipranjan; Pramanik, Arindam; Laskar, Aparna

Highlights: • Spherical and sheet shaped copper oxide nanoparticles were synthesized. • Physical characterizations of these nanoparticles were done by TEM, DLS, XRD, FTIR. • They showed shape dependent antibacterial activity on different bacterial strain. • They induced both membrane damage and ROS mediated DNA damage in bacteria. - Abstract: In this work, we synthesized spherical and sheet shaped copper oxide nanoparticles and their physical characterizations were done by the X-ray diffraction, fourier transform infrared spectroscopy, transmission electron microscopy and dynamic light scattering. The antibacterial activity of these nanoparticles was determined on both gram positive and gram negative bacterial. Sphericalmore » shaped copper oxide nanoparticles showed more antibacterial property on gram positive bacteria where as sheet shaped copper oxide nanoparticles are more active on gram negative bacteria. We also demonstrated that copper oxide nanoparticles produced reactive oxygen species in both gram negative and gram positive bacteria. Furthermore, they induced membrane damage as determined by atomic force microscopy and scanning electron microscopy. Thus production of and membrane damage are major mechanisms of the bactericidal activity of these copper oxide nanoparticles. Finally it was concluded that antibacterial activity of nanoparticles depend on physicochemical properties of copper oxide nanoparticles and bacterial strain.« less

The role of nano-particles in the field of thermal spray coating technology

NASA Astrophysics Data System (ADS)

Siegmann, Stephan; Leparoux, Marc; Rohr, Lukas

2005-06-01

Nano-particles play not only a key role in recent research fields, but also in the public discussions about health and safety in nanotechnology. Nevertheless, the worldwide activities in nano-particles research increased dramatically during the last 5 to 10 years. There are different potential routes for the future production of nano-particles at large scale. The main directions envisaged are mechanical milling, wet chemical reactions or gas phase processes. Each of the processes has its specific advantages and limitations. Mechanical milling and wet chemical reactions are typically time intensive and batch processes, whereas gas phase productions by flames or plasma can be carried out continuously. Materials of interest are mainly oxide ceramics, carbides, nitrides, and pure metals. Nano-ceramics are interesting candidates for coating technologies due to expected higher coating toughness, better thermal shock and wear resistance. Especially embedded nano-carbides and-nitrides offer homogenously distributed hard phases, which enhance coatings hardness. Thermal spraying, a nearly 100 years old and world wide established coating technology, gets new possibilities thanks to optimized, nano-sized and/or nano-structured powders. Latest coating system developments like high velocity flame spraying (HVOF), cold gas deposition or liquid suspension spraying in combination with new powder qualities may open new applications and markets. This article gives an overview on the latest activities in nano-particle research and production in special relation to thermal spray coating technology.

Incorporation of zinc oxide nanoparticles into chitosan-collagen 3D porous scaffolds: Effect on morphology, mechanical properties and cytocompatibility of 3D porous scaffolds.

PubMed

Ullah, Saleem; Zainol, Ismail; Idrus, Ruszymah Hj

2017-11-01

The zinc oxide nanoparticles (particles size <50nm) incorporated into chitosan-collagen 3D porous scaffolds and investigated the effect of zinc oxide nanoparticles incorporation on microstructure, mechanical properties, biodegradation and cytocompatibility of 3D porous scaffolds. The 0.5%, 1.0%, 2.0% and 4.0% zinc oxide nanoparticles chitosan-collagen 3D porous scaffolds were fabricated via freeze-drying technique. The zinc oxide nanoparticles incorporation effects consisting in chitosan-collagen 3D porous scaffolds were investigated by mechanical and swelling tests, and effect on the morphology of scaffolds examined microscopically. The biodegradation and cytocompatibility tests were used to investigate the effects of zinc oxide nanoparticles incorporation on the ability of scaffolds to use for tissue engineering application. The mean pore size and swelling ratio of scaffolds were decreased upon incorporation of zinc oxide nanoparticles however, the porosity, tensile modulus and biodegradation rate were increased upon incorporation of zinc oxide nanoparticles. In vitro culture of human fibroblasts and keratinocytes showed that the zinc oxide nanoparticles facilitated cell adhesion, proliferation and infiltration of chitosan-collagen 3D porous scaffolds. It was found that the zinc oxide nanoparticles incorporation enhanced porosity, tensile modulus and cytocompatibility of chitosan-collagen 3D porous scaffolds. Copyright © 2017 Elsevier B.V. All rights reserved.

Recent Advances in the Synthesis and Stabilization of Nickel and Nickel Oxide Nanoparticles: A Green Adeptness

PubMed Central

Rani, Aneela

2016-01-01

Green protocols for the synthesis of nanoparticles have been attracting a lot of attention because they are eco-friendly, rapid, and cost-effective. Nickel and nickel oxide nanoparticles have been synthesized by green routes and characterized for impact of green chemistry on the properties and biological effects of nanoparticles in the last five years. Green synthesis, properties, and applications of nickel and nickel oxide nanoparticles have been reported in the literature. This review summarizes the synthesis of nickel and nickel oxide nanoparticles using different biological systems. This review also provides comparative overview of influence of chemical synthesis and green synthesis on structural properties of nickel and nickel oxide nanoparticles and their biological behavior. It concludes that green methods for synthesis of nickel and nickel oxide nanoparticles are better than chemical synthetic methods. PMID:27413375

Optical Properties of Free and Embedded Small Nanoparticles

NASA Astrophysics Data System (ADS)

Idrobo, Juan

2008-03-01

It is well known that the absorption spectra, as well as the effective dielectric function, of nanoparticles in vacuum or surrounded by a dielectric medium can be obtained by classical Mie and Maxwell-Garnett theories. A limit as to how the particles can be for the theory to apply has not been established. Here I present theoretical results on the optical properties of small Ag, Au, and Si and Ge nanoparticles with tens of atoms in vacuum and in an embedded dielectric medium obtained from first-principles density-functional calculations. In particular, I will discuss the role that d-electron play on the optical properties of Ag and Au nanoparticles, and the cases when classical Mie and Maxwell-Garnett theories can be applied for nanoparticles of just few atoms in size and whose atoms are in bulk-like and not bulk-like positions. Comparison will be made for nanoparticles in vacuum and embedded in an alumina matrix. The quantum-mechanical results indicate that small nanoparticles in alumina can have an imprint on the effective dielectric function that is several times larger than would be predicted by Maxwell-Garnett theory for same-size particles. This work was supported by a GOALI NSF grant, DOE, the Office of Basic Energy Sciences, Division of Materials Sciences and Engineering, and Alcoa Inc. Collaborators: S. ögüt, K. Jackson, J. Jellinek, A. Halabica. R. F. Haglund, R. Magruder, S.J. Pennycook and S.T. Pantelides.

Excitons emissions and Raman scattering of ZnO nanoparticles embedded in BaF2 matrices by reactive magnetron sputtering.

PubMed

Zang, C H; Su, J F; Liu, Y C; Tang, C J; Fang, S J; Zhang, D M; Zhang, Y S

2011-11-01

ZnO nanoparticles embedded in BaF2 matrix were fabricated by rf magnetic sputtering technology. The optical properties of high quality ZnO nanoparticles, thermally post treated in a N2 atmosphere, were investigated by temperature-dependence photoluminescence measurement. Free exciton and localized exciton were observed at the low temperature. Free exciton peak was at 3.374 eV and localized exciton peak was at 3.420 eV, dominating the PL spectrum at 77 K. Free exciton transition was observed at 3.310 eV at room temperature, whereas the localized exciton transition was at 3.378 eV. The multiple-phonon Raman scattering spectrum showed that ZnO nanoparticles embedded in BaF2 matrix had a large deformation energy originated from lattice mismatch between ZnO and BaF2 matrix. Analysis of the fitting results from the temperature dependence of FWHM of ZnO exciton illustrated that the large value of gamma(ph) was good qualitative agreement with the large deformation potential.

X-ray absorption spectroscopy characterization of embedded and extracted nano-oxides

DOE PAGES

Stan, Tiberiu; Sprouster, David J.; Ofan, Avishai; ...

2016-12-29

Here, the chemistries and structures of both embedded and extracted Ysingle bondTisingle bondO nanometer-scale oxides in a nanostructured ferritic alloy (NFA) were probed by x-ray absorption spectroscopy (XAS). Y 2Ti 2O 7 is the primary embedded phase, while the slightly larger extracted oxides are primarily Y 2TiO 5. Analysis of the embedded nano-oxides is difficult partly due to the multiple Ti environments associated with different oxides and those still residing in matrix lattice sites. Thus, bulk extraction followed by selective filtration was used to isolate the larger Y 2TiO 5 oxides for XAS, while the smaller predominant embedded phase Ymore » 2Ti 2O 7 oxides passed through the filters and were analyzed using the log-ratio method.« less

Enhancement of algicidal properties of immobilized Bacillus methylotrophicus ZJU by coating with magnetic Fe₃O₄ nanoparticles and wheat bran.

PubMed

Sun, Pengfei; Hui, Cai; Wang, Sheng; Khan, Rashid Azim; Zhang, Qichun; Zhao, Yu-Hua

2016-01-15

Algicidal bacteria offer a promising option for killing cyanobacteria. In this study, a newly isolated strain of Bacillus methylotrophicus, ZJU, was used to control Microcystis aeruginosa. Analyses of relative reactive oxygen level, malondialdehyde content, superoxide dismutase activity, and fluorescence staining indicated that oxidative damage caused by the algicidal supernatant of strain ZJU mainly affected the cell membrane and consequently the membrane permeability and membrane potential of M. aeruginosa cells. Furthermore, an embedded immobilization technique was employed to improve the practical application of strain ZJU as an algicidal agent. On this basis, we proposed a novel concept of enhancing the algicidal properties of immobilized ZJU by adding Fe3O4 nanoparticles and wheat bran in the process of immobilization. Our studies showed that Fe3O4 nanoparticles conferred the immobilized bacteria with a magnetization of 30.87 emu/g, and this magnetization enabled efficient re-collection of the immobilized bacteria by magnetic means. Moreover, wheat bran endowed the immobilized bacteria with 10.34% higher algicidal activity than immobilized bacteria without wheat bran. The results indicate a novel concept of enhancing the algicidal property of bacteria against M. aeruginosa by adding Fe3O4 nanoparticles and wheat bran. Copyright © 2015 Elsevier B.V. All rights reserved.

Effets antibacteriens des nanoparticules de cuivre, oxyde de cuivre et oxyde de fer

NASA Astrophysics Data System (ADS)

Talantikit, Myriam

Population longevity tends to increase in occidental countries inducing an increment in medical implants use. Resistant bacteria may contaminate those implants causing nosocomial infections. Common treatment for bacteria is antibiotic, used mainly for their speed and efficacy. An overuse of antibiotics induced bacteria to be resistant to them. Adding to this issue, when bacteria are in a certain environment, bacteria tend to communicate between themselves and create a biofilm (protective layer). Polysaccharides forming the biofilm don't allow antibiotics to penetrate inside the biofilm. Bacteria in a biofilm are extremely hard to kill. An alternative to resolve all those issues is to use nanoparticles as antimicrobial agents. They are known to have antibacterial effect. But the. The main objective is to study the effects develop "nano-biotics" that can prevent nosocomial infections due to surgical implants. In this project, we evaluated in vitro antibacterial effects of some nanoparticles (copper, copper oxide, superparamagnetic iron oxide, and superparamagnetic iron oxide coupled with nitric oxide (NO) on bacteria. Nanoparticles and microparticles characterizations have been done to determine their size, their composition and their surface chemistry using TEM and FTIR. Different parameters play a crucial role in antibacterial toxicity of particles. First, we adapted microbiological tests to elucidate nanoparticles biotoxicity. Then, pure copper and copper oxide nanoparticles have been studied to determine the importance of nanoparticles composition in toxicity. Size is another important parameter, explaining our interest to study both copper micro and nanoparticles on bacteria (S.aureus and E.coli). Bacterial toxicity of superparamagnetic iron oxide nanoparticles, used as a magnetic vehicle to deliver NO (antibacterial molecule), has been studied. Once NO is delivered, iron oxide nanoparticles still react with bacteria. Finally, copper and copper oxide nanoparticles were in contact with S.aureus biofilm to see their effect and the difference with planktonic bacteria. Our nanoparticles characterizations of copper shows that these nanoparticles are not completely pure but a thin oxide layer at their surface forms, which can lower their toxicity. Our results on the importance of particles size, confirm what was seen in the literature. Nanoparticles seems to be more toxic than microparticles. Superparamagnetic iron oxide nanoparticles results, alone, don't show a big antibacterial effect. Preliminary tests were done on NO coupled nanoparticles, and it seems there is an antibacterial effect. However, NO results are not conclusive because of some technical difficulties during NO attachment on nanoparticles. These studies allowed us to show that copper and copper oxide nanoparticles were a good antibacterial but the dose used might be too important for biomedical applications. Superparamagnetic iron oxide nanoparticles have a low antibacterial effect but are biocompatible. They are an excellent candidate as vehicle for NO delivery to a specific site. These studies are the first effort made to the development of new antimicrobial agents based on metallic nanoparticles. Key words: nanoparticles, copper, oxide copper, biofilm, antibacterial, iron oxide, nitric oxide.

Liposomes Loaded with Hydrophobic Iron Oxide Nanoparticles: Suitable T₂ Contrast Agents for MRI.

PubMed

Martínez-González, Raquel; Estelrich, Joan; Busquets, Maria Antònia

2016-07-27

There has been a recent surge of interest in the use of superparamagnetic iron oxide nanoparticles (SPIONs) as contrast agents (CAs) for magnetic resonance imaging (MRI), due to their tunable properties and their low toxicity compared with other CAs such as gadolinium. SPIONs exert a strong influence on spin-spin T₂ relaxation times by decreasing the MR signal in the regions to which they are delivered, consequently yielding darker images or negative contrast. Given the potential of these nanoparticles to enhance detection of alterations in soft tissues, we studied the MRI response of hydrophobic or hydrophilic SPIONs loaded into liposomes (magnetoliposomes) of different lipid composition obtained by sonication. These hybrid nanostructures were characterized by measuring several parameters such as size and polydispersity, and number of SPIONs encapsulated or embedded into the lipid systems. We then studied the influence of acyl chain length as well as its unsaturation, charge, and presence of cholesterol in the lipid bilayer at high field strength (7 T) to mimic the conditions used in preclinical assays. Our results showed a high variability depending on the nature of the magnetic particles. Focusing on the hydrophobic SPIONs, the cholesterol-containing samples showed a slight reduction in r₂, while unsaturation of the lipid acyl chain and inclusion of a negatively charged lipid into the bilayer appeared to yield a marked increase in negative contrast, thus rendering these magnetoliposomes suitable candidates as CAs, especially as a liver CA.

Fundamental aspects of regenerative cerium oxide nanoparticles and their applications in nanobiotechnology

NASA Astrophysics Data System (ADS)

Patil, Swanand D.

Cerium oxide has been used extensively for various applications over the past two decades. The use of cerium oxide nanoparticles is beneficial in present applications and can open avenues for future applications. The present study utilizes the microemulsion technique to synthesize uniformly distributed cerium oxide nanoparticles. The same technique was also used to synthesize cerium oxide nanoparticles doped with trivalent elements (La and Nd). The fundamental study of cerium oxide nanoparticles identified variations in properties as a function of particle size and also due to doping with trivalent elements (La and Nd). It was found that the lattice parameter of cerium oxide nanoparticles increases with decrease in particle size. Also Raman allowed mode shift to lower energies and the peak at 464 cm-1 becomes broader and asymmetric. The size dependent changes in cerium oxide were correlated to increase in oxygen vacancy concentration in the cerium oxide lattice. The doping of cerium oxide nanoparticles with trivalent elements introduces more oxygen vacancies and expands the cerium oxide lattice further (in addition to the lattice expansion due to the size effect). The lattice expansion is greater for La-doped cerium oxide nanoparticles compared to Nd-doping due to the larger ionic radius of La compared to Nd, the lattice expansion is directly proportional to the dopant concentration. The synthesized cerium oxide nanoparticles were used to develop an electrochemical biosensor of hydrogen peroxide (H2O2). The sensor was useful to detect H2O2 concentrations as low as 1muM in water. Also the preliminary testing of the sensor on tomato stem and leaf extracts indicated that the sensor can be used in practical applications such as plant physiological studies etc. The nanomolar concentrations of cerium oxide nanoparticles were also found to be useful in decreasing ROS (reactive oxygen species) mediated cellular damages in various in vitro cell cultures. Cerium oxide nanoparticles reduced the cellular damages to the normal breast epithelial cell line (CRL 8798) induced by X-rays and to the Keratinocyte cell line induced by UV irradiation. Cerium oxide nanoparticles were also found to be neuroprotective to adult rat spinal cord and retinal neurons. We propose that cerium oxide nanoparticles act as free radical scavenger (via redox reactions on its surface) to decrease the ROS induced cellular damages. Additionally, UV-visible spectroscopic studies indicated that cerium oxide nanoparticles possess auto-regenerative property by switching its oxidation state between Ce3+ and Ce4+. The auto-regenerative antioxidant property of these nanoparticles appears to be a key component in all the biological applications discussed in the present study.

Synthesis and characterization of dextran-coated iron oxide nanoparticles

NASA Astrophysics Data System (ADS)

Predescu, Andra Mihaela; Matei, Ecaterina; Berbecaru, Andrei Constantin; Pantilimon, Cristian; Drăgan, Claudia; Vidu, Ruxandra; Predescu, Cristian; Kuncser, Victor

2018-03-01

Synthesis and characterization of iron oxide nanoparticles coated with a large molar weight dextran for environmental applications are reported. The first experiments involved the synthesis of iron oxide nanoparticles which were coated with dextran at different concentrations. The synthesis was performed by a co-precipitation technique, while the coating of iron oxide nanoparticles was carried out in solution. The obtained nanoparticles were characterized by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction spectrometry, Fourier transform infrared spectroscopy and superconducting quantum interference device magnetometry. The results demonstrated a successful coating of iron oxide nanoparticles with large molar weight dextran, of which agglomeration tendency depended on the amount of dextran in the coating solution. SEM and TEM observations have shown that the iron oxide nanoparticles are of about 7 nm in size.

Antibacterial effect of composite resins containing quaternary ammonium polyethyleneimine nanoparticles

NASA Astrophysics Data System (ADS)

Yudovin-Farber, Ira; Beyth, Nurit; Weiss, Ervin I.; Domb, Abraham J.

2010-02-01

Quaternary ammonium polyethyleneimine (QA-PEI)-based nanoparticles were synthesized by crosslinking with dibromopentane followed by N-alkylation with various alkyl halides and further N-methylation with methyl iodide. Insoluble pyridinium-type particles were prepared by suspension polymerization of 4-vinyl pyridine followed by N-alkylation with alkyl halides. Polyamine-based nanoparticles embedded in restorative composite resin at 1% w/w were tested for antibacterial activity against Streptococcus mutans using direct contact test. Activity analysis revealed that the alkyl chain length of the QA-PEI nanoparticles plays a significant role in antibacterial activity of the reagent. The most potent compound was octyl-alkylated QA-PEI embedded in restorative composite resin at 1% w/w that totally inhibited S. mutans growth in 3-month-aged samples. This data indicates that restorative composite resin with antibacterial properties can be produced by the incorporation of QA-PEI nanoparticles.

Synthesis and anti-fungal effect of silver nanoparticles–chitosan composite particles

PubMed Central

Wang, Lung-Shuo; Wang, Chih-Yu; Yang, Chih-Hui; Hsieh, Chen-Ling; Chen, Szu-Yu; Shen, Chi-Yen; Wang, Jia-Jung; Huang, Keng-Shiang

2015-01-01

Silver nanoparticles have been used in various fields, and several synthesis processes have been developed. The stability and dispersion of the synthesized nanoparticles is vital. The present article describes a novel approach for one-step synthesis of silver nanoparticles–embedded chitosan particles. The proposed approach was applied to simultaneously obtain and stabilize silver nanoparticles in a chitosan polymer matrix in-situ. The diameter of the synthesized chitosan composite particles ranged from 1.7 mm to 2.5 mm, and the embedded silver nanoparticles were measured to be 15±3.3 nm. Further, the analyses of ultraviolet-visible spectroscopy, energy dispersive spectroscopy, and X-ray diffraction were employed to characterize the prepared composites. The results show that the silver nanoparticles were distributed over the surface and interior of the chitosan spheres. The fabricated spheres had macroporous property, and could be used for many applications such as fungicidal agents in the future. PMID:25878501

Nanofibrillated Cellulose and Copper Nanoparticles Embedded in Polyvinyl Alcohol Films for Antimicrobial Applications

PubMed Central

Zhong, Tuhua; Oporto, Gloria S.; Jaczynski, Jacek; Jiang, Changle

2015-01-01

Our long-term goal is to develop a hybrid cellulose-copper nanoparticle material as a functional nanofiller to be incorporated in thermoplastic resins for efficiently improving their antimicrobial properties. In this study, copper nanoparticles were first synthesized through chemical reduction of cupric ions on TEMPO nanofibrillated cellulose (TNFC) template using borohydride as a copper reducing agent. The resulting hybrid material was embedded into a polyvinyl alcohol (PVA) matrix using a solvent casting method. The morphology of TNFC-copper nanoparticles was analyzed by transmission electron microscopy (TEM); spherical copper nanoparticles with average size of 9.2 ± 2.0 nm were determined. Thermogravimetric analysis and antimicrobial performance of the films were evaluated. Slight variations in thermal properties between the nanocomposite films and PVA resin were observed. Antimicrobial analysis demonstrated that one-week exposure of nonpathogenic Escherichia coli DH5α to the nanocomposite films results in up to 5-log microbial reduction. PMID:26137482

Novel solid-state synthesis of α-Fe and Fe3O4 nanoparticles embedded in a MgO matrix

NASA Astrophysics Data System (ADS)

Schneeweiss, O.; Zboril, R.; Pizurova, N.; Mashlan, M.; Petrovsky, E.; Tucek, J.

2006-01-01

Thermally induced reduction of amorphous Fe2O3 nanopowder (2-3 nm) with nanocrystalline Mg (~20 nm) under a hydrogen atmosphere is presented as a novel route to obtain α-Fe and Fe3O4 magnetic nanoparticles dispersed in a MgO matrix. The phase composition, structural and magnetic properties, size and morphology of the nanoparticles were monitored by x-ray diffraction, 57Fe Mössbauer spectroscopy at temperatures of 24-300 K, transmission electron microscopy and magnetic measurements. Spherical magnetite nanoparticles prepared at a reaction temperature of 300 °C revealed a well-defined structure, with a ratio of tetrahedral to octahedral Fe sites of 1/2 being common for the bulk material. A narrow particle size distribution (20-30 nm) and high saturation magnetization (95 ± 5 A m2 kg-1) predispose the magnetite nanoparticles to various applications, including magnetic separation processes. The Verwey transition of Fe3O4 nanocrystals was found to be decreased to about 80 K. The deeper reduction of amorphous ferric oxide at 600 °C allows α-Fe (40-50 nm) nanoparticles to be synthesized with a coercive force of about 30 mT. They have a saturation magnetization 2.2 times higher than that of synthesized magnetite nanoparticles, which corresponds well with the ratio usually found for the pure bulk phases. The magnetic properties of α-Fe nanocrystals combined with the high chemical and thermal stability of the MgO matrix makes the prepared nanocomposite useful for various magnetic applications.

The fabrication of nanopatterns with Au nanoparticles-embedded micelles via nanoimprint lithography.

PubMed

Lee, Jung-Pil; Kim, Eun-Uk; Koh, Haeng-Deog; Kang, Nam-Goo; Jung, Gun-Young; Lee, Jae-Suk

2009-09-09

We fabricated nanopatterns with Au nanoparticles-embedded micelles (Au-micelles) by self-assembly of block copolymers via nanoimprint lithography. The micelle structure prepared by self-assembled block copolymers was used as a template for the synthesis of Au nanoparticles (Au NPs). Au NPs were synthesized in situ inside the micelles of polystyrene-block-poly(2-vinylpyridine) (PS- b-P2VP). Au-micelles were arranged on the trenches of the polymer template, which was imprinted by nanoimprint lithography. The fabrication of line-type and dot-type nanopatterns was carried out by the combined method. In addition, multilayer nanopatterns of the Au-micelles were also proposed.

Radially and azimuthally polarized laser induced shape transformation of embedded metallic nanoparticles in glass.

PubMed

Tyrk, Mateusz A; Zolotovskaya, Svetlana A; Gillespie, W Allan; Abdolvand, Amin

2015-09-07

Radially and azimuthally polarized picosecond (~10 ps) pulsed laser irradiation at 532 nm wavelength led to the permanent reshaping of spherical silver nanoparticles (~30 - 40 nm in diameter) embedded in a thin layer of soda-lime glass. The observed peculiar shape modifications consist of a number of different orientations of nano-ellipsoids in the cross-section of each written line by laser. A Second Harmonic Generation cross-sectional scan method from silver nanoparticles in transmission geometry was adopted for characterization of the samples after laser modification. The presented approach may lead to sophisticated marking of information in metal-glass nanocomposites.

In situ Synthesis of Metal Nanoparticle Embedded Free Standing Multifunctional PDMS Films.

PubMed

Goyal, Anubha; Kumar, Ashavani; Patra, Prabir K; Mahendra, Shaily; Tabatabaei, Salomeh; Alvarez, Pedro J J; John, George; Ajayan, Pulickel M

2009-07-01

We demonstrate a simple one-step method for synthesizing noble metal nanoparticle embedded free standing polydimethylsiloxane (PDMS) composite films. The process involves preparing a homogenous mixture of metal salt (silver, gold and platinum), silicone elastomer and the curing agent (hardener) followed by curing. During the curing process, the hardener crosslinks the elastomer and simultaneously reduces the metal salt to form nanoparticles. This in situ method avoids the use of any external reducing agent/stabilizing agent and leads to a uniform distribution of nanoparticles in the PDMS matrix. The films were characterized using UV-Vis spectroscopy, transmission electron microscopy and X-ray photoemission spectroscopy. The nanoparticle-PDMS films have a higher Young's modulus than pure PDMS films and also show enhanced antibacterial properties. The metal nanoparticle-PDMS films could be used for a number of applications such as for catalysis, optical and biomedical devices and gas separation membranes. Copyright © 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Strong coupling-like phenomenon in single metallic nanoparticle embedded in molecular J-aggregates

NASA Astrophysics Data System (ADS)

Feng, Xin; Wang, Chen; Ma, Hongjing; Chen, Yuanyuan; Duan, Gaoyan; Zhang, Pengfei; Song, Gang

2018-02-01

Strong coupling-like phenomenon between plasmonic cavities and emitters provides a new way to realize the quantum-like effect controlling at microscale/nanoscale. We investigate the strong coupling-like phenomenon in the structure of single metallic nanoparticle embedded in molecular J-aggregates by the classical simulation method and show that the size of the metallic nanoparticle and the oscillator strength of molecular J-aggregates impact the strong coupling-like phenomenon. The strong coupling-like phenomenon is induced by the interactions between two dipoles formed by the metallic nanoparticle and molecular J-aggregates or the interactions between the dipole generated from molecular J-aggregates and the quadrupole generated from the metallic nanoparticle. The strong coupling-like phenomenon appears evidently with the increase in oscillator strength of molecular J-aggregates. The detuning energy linearly decreases with the increase in radius of the metallic nanoparticle. Our structure has potential applications in quantum networks, quantum key distributions and so on.

Magneto-optical Faraday rotation of semiconductor nanoparticles embedded in dielectric matrices.

PubMed

Savchuk, Andriy I; Stolyarchuk, Ihor D; Makoviy, Vitaliy V; Savchuk, Oleksandr A

2014-04-01

Faraday rotation has been studied for CdS, CdTe, and CdS:Mn semiconductor nanoparticles synthesized by colloidal chemistry methods. Additionally these materials were prepared in a form of semiconductor nanoparticles embedded in polyvinyl alcohol films. Transmission electron microscopy and atomic force microscopy analyses served as confirmation of nanocrystallinity and estimation of the average size of the nanoparticles. Spectral dependence of the Faraday rotation for the studied nanocrystals and nanocomposites is correlated with a blueshift of the absorption edge due to the confinement effect in zero-dimensional structures. Faraday rotation spectra and their temperature behavior in Mn-doped nanocrystals demonstrates peculiarities, which are associated with s, p-d exchange interaction between Mn²⁺ ions and band carriers in diluted magnetic semiconductor nanostructures.

MXP(M = Co/Ni)@carbon core-shell nanoparticles embedded in 3D cross-linked graphene aerogel derived from seaweed biomass for hydrogen evolution reaction.

PubMed

Zhao, Wentong; Lu, Xiaoqing; Selvaraj, Manickam; Wei, Wei; Jiang, Zhifeng; Ullah, Nabi; Liu, Jie; Xie, Jimin

2018-05-24

Low-cost electrocatalysts play an important role in the hydrogen evolution reaction (HER). Particularly, transition metal phosphides (TMPs) are widely applied in the development of HER electrocatalysts. To improve the poor electrochemical reaction kinetics of HER, we introduce a facile way to synthesize carbon core-shell materials containing cobalt phosphide nanoparticles embedded in different graphene aerogels (GAs) (CoP@C-NPs/GA-x (x = 5, 10 and 20)) using seaweed biomass as precursors. The synthesized CoP@C-NPs/GA-5 exhibits efficient catalytic activity with small overpotentials of 120 and 225 mV at current densities of 10 mA cm-2, along with the low Tafel slopes of 57 and 66 mV dec-1, for HER in acidic and alkaline electrolytes, respectively. Compared with carbon aerogel (CA) containing cobalt phosphide nanoparticles (CoP-NPs@CA), the stability of CoP@C-NPs/GA-5 coated with carbon-shells (∼0.8 nm) was significantly improved in acidic electrolytes. We also prepared carbon core-shell materials containing nickel phosphide nanoparticles embedded in GA (Ni2P@C-NPs/GA) to further expand this synthetic route. The graphene-Ni2P@C aerogel shows a similar morphology and better catalytic activity for HER in acidic and alkaline electrolytes. In this work, the robust three-dimensional (3D) GA matrix with abundant open pores and large surface area provides unblocked channels for electrolyte contact and electronic transfer and enables very close contact between the catalyst and electrolyte. The MxP@C core-shell structure prevents the inactivation of MxP NPs during HER processes, and the thin graphene oxide (GO) layers and 3D CA together build up a 3D conductive matrix, which not only adjusts the volume expansion of MxP NPs as well as preventing their aggregation, but also provides a 3D conductive pathway for rapid charge transfer processes. The present synthetic strategy for phosphides via in situ phosphorization with 3D GA can be extended to other novel high-performance catalysts. The simple synthesis and efficient catalytic activity of MXP@C-NPs/GA indicate good application prospects in HER.

Mechanistic study on antibacterial action of zinc oxide nanoparticles synthesized using green route.

PubMed

Happy Agarwal; Soumya Menon; Venkat Kumar, S; Rajeshkumar, S

2018-04-25

A large array of diseases caused by bacterial pathogens and origination of multidrug resistance in their gene provokes the need of developing new vectors or novel drug molecules for effective drug delivery and thus, better treatment of disease. The nanoparticle has emerged as a novel drug molecule in last decade and has been used in various industrial fields like cosmetics, healthcare, agricultural, pharmaceuticals due to their high optical, electronic, medicinal properties. Use of nanoparticles as an antibacterial agent remain in current studies with metal nanoparticles like silver, gold, copper, iron and metal oxide nanoparticles like zinc oxide, copper oxide, titanium oxide and iron oxide nanoparticles. The high anti-bacterial activity of nanoparticles is due to their large surface area to volume ratio which allows binding of a large number of ligands on nanoparticle surface and hence, its complexation with receptors present on the bacterial surface. Green synthesis of Zinc Oxide Nanoparticle (ZnO NP) and its anti-bacterial application has been particularly discussed in the review literature. The present study highlights differential nanoparticle attachment to gram + and gram - bacterial surface and different mechanism adopted by nanoparticle for bacterial control. Pharmacokinetics and applications of ZnO NP are also discussed briefly. Copyright © 2018 Elsevier B.V. All rights reserved.

MIL-100 derived nitrogen-embodied carbon shells embedded with iron nanoparticles

NASA Astrophysics Data System (ADS)

Mao, Chengyu; Kong, Aiguo; Wang, Yuan; Bu, Xianhui; Feng, Pingyun

2015-06-01

The use of metal-organic frameworks (MOFs) as templates and precursors to synthesize new carbon materials with controllable morphology and pre-selected heteroatom doping holds promise for applications as efficient non-precious metal catalysts. Here, we report a facile pyrolysis pathway to convert MIL-100 into nitrogen-doped carbon shells encapsulating Fe nanoparticles in a comparative study involving multiple selected nitrogen sources. The hierarchical porous architecture, embedded Fe nanoparticles, and nitrogen decoration endow this composite with a superior oxygen reduction activity. Furthermore, the excellent durability and high methanol tolerance even outperform the commercial Pt-C catalyst.The use of metal-organic frameworks (MOFs) as templates and precursors to synthesize new carbon materials with controllable morphology and pre-selected heteroatom doping holds promise for applications as efficient non-precious metal catalysts. Here, we report a facile pyrolysis pathway to convert MIL-100 into nitrogen-doped carbon shells encapsulating Fe nanoparticles in a comparative study involving multiple selected nitrogen sources. The hierarchical porous architecture, embedded Fe nanoparticles, and nitrogen decoration endow this composite with a superior oxygen reduction activity. Furthermore, the excellent durability and high methanol tolerance even outperform the commercial Pt-C catalyst. Electronic supplementary information (ESI) available: Material synthesis and elemental analysis, electrochemistry measurements, and additional figures. See DOI: 10.1039/c5nr02346g

Optical properties of metal nanoparticles embedded in amorphous silicon analysed using discrete dipole approximation

NASA Astrophysics Data System (ADS)

Fantoni, Alessandro; Fernandes, Miguel; Vygranenko, Yuri; Vieira, Manuela; Oliveira-Silva, Rui P.; Prazeres, D. M. F.; Ribeiro, Ana P. C.; Alegria, Elisabete C. B. A.

2018-02-01

Localized surface plasmons (LSP) can be excited in metal nanoparticles (NP) by UV, visible or NIR light and are described as coherent oscillation of conduction electrons. Taking advantage of the tunable optical properties of NPs, we propose the realization of a plasmonic structure, based on the LSP interaction of NP with an embedding matrix of amorphous silicon. This study is directed to define the characteristics of NP and substrate necessary to the development of a LSP proteomics sensor that, once provided immobilized antibodies on its surface, will screen the concentration of selected antigens through the determination of LSPR spectra and peaks of light absorption. Metals of interest for NP composition are: Aluminium and Gold. Recent advances in nanoparticle production techniques allow almost full control over shapes and size, permitting full control over their optical and plasmonic properties and, above all, over their responsive spectra. Analytical solution is only possible for simple NP geometries, therefore our analysis, is realized recurring to computer simulation using the Discrete Dipole Approximation method (DDA). In this work we use the free software DDSCAT to study the optical properties of metal nanoparticles embedded in an amorphous silicon matrix, as a function of size, shape, aspect-ratio and metal type. Experimental measurements realized with arrays of metal nanoparticles are compared with the simulations.

A highly active PtCu3 intermetallic core-shell, multilayered Pt-skin, carbon embedded electrocatalyst produced by a scale-up sol-gel synthesis.

PubMed

Bele, M; Jovanovič, P; Pavlišič, A; Jozinović, B; Zorko, M; Rečnik, A; Chernyshova, E; Hočevar, S; Hodnik, N; Gaberšček, M

2014-11-07

We present a novel, scaled-up sol-gel synthesis which enables one to produce 20 g batches of highly active and stable carbon supported PtCu3 nanoparticles as cathode materials for low temperature fuel cell application. We confirm the presence of an ordered intermetallic phase underneath a multilayered Pt-skin together with firm embedment of nanoparticles in the carbon matrix.

Studies of Positrons Trapped at Quantum-Dot Like Particles Embedded in Metal Surfaces

NASA Astrophysics Data System (ADS)

Fazleev, N. G.; Nadesalingam, M. P.; Weiss, A. H.

2009-03-01

Experimental studies of the positron annihilation induced Auger electron (PAES) spectra from the Fe-Cu alloy surfaces with quantum-dot like Cu nanoparticles embedded in Fe show that the PAES signal from Cu increase rapidly as the concentration of Cu is enhanced by vacuum annealing. These measurements indicate that almost 75% of positrons that annihilate with core electrons due so with Cu even though the surface concentration of Cu as measured by EAES is only 6%. This result suggests that positrons become localized at sites at the surface containing high concentration of Cu atoms before annihilation. These experimental results are investigated theoretically by performing calculations of the "image-potential" positron surface states and annihilation characteristics of the surface trapped positrons with relevant Fe and Cu core-level electrons for the clean Fe(100) and Cu(100) surfaces and for the Fe(100) surface with quantum-dot like Cu nanoparticles embedded in the top atomic layers of the host substrate. Estimates of the positron binding energy and positron annihilation characteristics reveal their strong sensitivity to the nanoparticle coverage. Computed core annihilation probabilities are compared with experimental ones estimated from the measured Auger peak intensities. The observed behavior of the Fe and Cu PAES signal intensities is explained by theoretical calculations as being due to trapping of positrons in the regions of Cu nanoparticles embedded in the top atomic layers of Fe.

In vitro assessment of the antimicrobial activity of silver and zinc oxide nanoparticles against fish pathogens.

PubMed

Shaalan, Mohamed Ibrahim; El-Mahdy, Magdy Mohamed; Theiner, Sarah; El-Matbouli, Mansour; Saleh, Mona

2017-07-21

Antibiotic resistance is a global issue that threatens public health. The excessive use of antibiotics contributes to this problem as the genes of antibiotic resistance can be transferred between the bacteria in humans, animals and aquatic organisms. Metallic nanoparticles could serve as future substitutes for some conventional antibiotics because of their antimicrobial activity. The aim of this study was to evaluate the antimicrobial effects of silver and zinc oxide nanoparticles against major fish pathogens and assess their safety in vitro. Silver nanoparticles were synthesized by chemical reduction and characterized with UV-Vis spectroscopy, transmission electron microscopy and zeta sizer. The concentrations of silver and zinc oxide nanoparticles were measured using inductively coupled plasma-mass spectrometry. Subsequently, silver and zinc oxide nanoparticles were tested for their antimicrobial activity against Aeromonas hydrophila, Aeromonas salmonicida subsp. salmonicida, Edwardsiella ictaluri, Edwardsiella tarda, Francisella noatunensis subsp. orientalis, Yersinia ruckeri and Aphanomyces invadans and the minimum inhibitory concentrations were determined. MTT assay was performed on eel kidney cell line (EK-1) to determine the cell viability after incubation with nanoparticles. The interaction between silver nanoparticles and A. salmonicida was investigated by transmission electron microscopy. The tested nanoparticles exhibited marked antimicrobial activity. Silver nanoparticles inhibited the growth of both A. salmonicida and A. invadans at a concentration of 17 µg/mL. Zinc oxide nanoparticles inhibited the growth of A. salmonicida, Y. ruckeri and A. invadans at concentrations of 15.75, 31.5 and 3.15 µg/mL respectively. Silver nanoparticles showed higher cell viability when compared to zinc oxide nanoparticles in the MTT assay. Transmission electron microscopy showed the attachment of silver nanoparticles to the bacterial membrane and disruption of its integrity. This is the first study on inhibitory effects of silver and zinc oxide nanoparticles towards A. salmonicida and A. invadans. Moreover, zinc oxide nanoparticles inhibited the growth of Y. ruckeri. In low concentrations, silver nanoparticles were less cytotoxic than zinc oxide nanoparticles and represent an alternative antimicrobial compound against A. hydrophila, A. salmonicida and A. invadans.

Targeted iron oxide nanoparticles for the enhancement of radiation therapy

PubMed Central

Hauser, Anastasia K.; Mitov, Mihail I.; Daley, Emily F.; McGarry, Ronald C.; Anderson, Kimberly W.; Hilt, J. Zach

2017-01-01

To increase the efficacy of radiation, iron oxide nanoparticles can be utilized for their ability to produce reactive oxygen species (ROS). Radiation therapy promotes leakage of electrons from the electron transport chain and leads to an increase in mitochondrial production of the superoxide anion which is converted to hydrogen peroxide by superoxide dismutase. Iron oxide nanoparticles can then catalyze the reaction from hydrogen peroxide to the highly reactive hydroxyl radical. Therefore, the overall aim of this project was to utilize iron oxide nanoparticles conjugated to a cell penetrating peptide, TAT, to escape lysosomal encapsulation after internalization by cancer cells and catalyze hydroxyl radical formation. It was determined that TAT functionalized iron oxide nanoparticles and uncoated iron oxide nanoparticles resulted in permeabilization of the lysosomal membranes. Additionally, mitochondrial integrity was compromised when A549 cells were treated with both TAT-functionalized nanoparticles and radiation. Pre-treatment with TAT-functionalized nanoparticles also significantly increased the ROS generation associated with radiation. A long term viability study showed that TAT-functionalized nanoparticles combined with radiation resulted in a synergistic combination treatment. This is likely due to the TAT-functionalized nanoparticles sensitizing the cells to subsequent radiation therapy, because the nanoparticles alone did not result in significant toxicities. PMID:27521615

In vitro cytotoxicity of iron oxide nanoparticles: effects of chitosan and polyvinyl alcohol as stabilizing agents

NASA Astrophysics Data System (ADS)

Tran, Phong A.; Nguyen, Hiep T.; Fox, Kate; Tran, Nhiem

2018-03-01

Iron oxide magnetic nanoparticles have significant potential in biomedical applications such as in diagnosis, imaging and therapeutic agent delivery. The choice of stabilizers and surface functionalization is important as it is known to strongly influence the cytotoxicity of the nanoparticles. The present study aimed at investigating the effects of surface charges on the cytotoxicity of iron oxide nanoparticles. We used a co-precipitation method to synthesize iron oxide nanoparticles which were then stabilized with either chitosan (CS) or polyvinyl alcohol (PVA) which have net positive charge and zero charge at physiological pH, respectively. The nanoparticles were characterized in terms of size, charges and chemical oxidation state. Cytotoxicity of the nanoparticles was assessed using mouse fibroblast cells and was correlated with surface charges of the nanoparticles and their aggregation.

Chemically synthesized TiO2 and PANI/TiO2 thin films for ethanol sensing applications

NASA Astrophysics Data System (ADS)

Gawri, Isha; Ridhi, R.; Singh, K. P.; Tripathi, S. K.

2018-02-01

Ethanol sensing properties of chemically synthesized titanium dioxide (TiO2) and polyaniline/titanium dioxide nanocomposites (PANI/TiO2) had been performed at room temperature. In-situ oxidative polymerization process had been employed with aniline as a monomer in presence of anatase titanium dioxide nanoparticles. The prepared samples were structurally and morphologically characterized by x-ray diffraction, fourier transform infrared spectra, high resolution-transmission electron microscopy and field emission-scanning electron microscopy. The crystallinity of PANI/TiO2 nanocomposite was revealed by XRD and FTIR spectra confirmed the presence of chemical bonding between the polymer chains and metal oxide nanoparticles. HR-TEM micrographs depicted that TiO2 particles were embedded in polymer matrix, which provides an advantage over pure TiO2 nanoparticles in efficient adsorption of vapours. These images also revealed that the TiO2 nanoparticles were irregular in shape with size around 17 nm. FE-SEM studies revealed that in the porous structure of PANI/TiO2 film, the intercalation of TiO2 in PANI chains provides an advantage over pure TiO2 film for uniform interaction with ethanol vapors. The sensitivity values of prepared samples were examined towards ethanol vapours at room temperature. The PANI/TiO2 nanocomposite exhibited better sensing response and faster response-recovery examined at different ethanol concentrations ranging from 5 ppm to 20 ppm in comparison to pure TiO2 nanoparticles. The increase in vapour sensing of PANI/TiO2 sensing film as compared to pure TiO2 film had been explained in detail with the help of gas sensing mechanism of TiO2 and PANI/TiO2. This provides strong evidence that gas sensing properties of TiO2 had been considerably improved and enhanced with the addition of polymer matrix.

Modulation of population density and size of silver nanoparticles embedded in bacterial cellulose via ammonia exposure: visual detection of volatile compounds in a piece of plasmonic nanopaper

NASA Astrophysics Data System (ADS)

Heli, B.; Morales-Narváez, E.; Golmohammadi, H.; Ajji, A.; Merkoçi, A.

2016-04-01

The localized surface plasmon resonance exhibited by noble metal nanoparticles can be sensitively tuned by varying their size and interparticle distances. We report that corrosive vapour (ammonia) exposure dramatically reduces the population density of silver nanoparticles (AgNPs) embedded within bacterial cellulose, leading to a larger distance between the remaining nanoparticles and a decrease in the UV-Vis absorbance associated with the AgNP plasmonic properties. We also found that the size distribution of AgNPs embedded in bacterial cellulose undergoes a reduction in the presence of volatile compounds released during food spoilage, modulating the studied nanoplasmonic properties. In fact, such a plasmonic nanopaper exhibits a change in colour from amber to light amber upon the explored corrosive vapour exposure and from amber to a grey or taupe colour upon fish or meat spoilage exposure. These phenomena are proposed as a simple visual detection of volatile compounds in a flexible, transparent, permeable and stable single-use nanoplasmonic membrane, which opens the way to innovative approaches and capabilities in gas sensing and smart packaging.The localized surface plasmon resonance exhibited by noble metal nanoparticles can be sensitively tuned by varying their size and interparticle distances. We report that corrosive vapour (ammonia) exposure dramatically reduces the population density of silver nanoparticles (AgNPs) embedded within bacterial cellulose, leading to a larger distance between the remaining nanoparticles and a decrease in the UV-Vis absorbance associated with the AgNP plasmonic properties. We also found that the size distribution of AgNPs embedded in bacterial cellulose undergoes a reduction in the presence of volatile compounds released during food spoilage, modulating the studied nanoplasmonic properties. In fact, such a plasmonic nanopaper exhibits a change in colour from amber to light amber upon the explored corrosive vapour exposure and from amber to a grey or taupe colour upon fish or meat spoilage exposure. These phenomena are proposed as a simple visual detection of volatile compounds in a flexible, transparent, permeable and stable single-use nanoplasmonic membrane, which opens the way to innovative approaches and capabilities in gas sensing and smart packaging. Electronic supplementary information (ESI) available: Details on the estimations of evaporation rates and limits of detection, ESI figures and author contributions. See DOI: 10.1039/c6nr00537c

Nanoscale semiconductor-insulator-metal core/shell heterostructures: facile synthesis and light emission

NASA Astrophysics Data System (ADS)

Li, Gong Ping; Chen, Rui; Guo, Dong Lai; Wong, Lai Mun; Wang, Shi Jie; Sun, Han Dong; Wu, Tom

2011-08-01

Controllably constructing hierarchical nanostructures with distinct components and designed architectures is an important theme of research in nanoscience, entailing novel but reliable approaches of bottom-up synthesis. Here, we report a facile method to reproducibly create semiconductor-insulator-metal core/shell nanostructures, which involves first coating uniform MgO shells onto metal oxide nanostructures in solution and then decorating them with Au nanoparticles. The semiconductor nanowire core can be almost any material and, herein, ZnO, SnO2 and In2O3 are used as examples. We also show that linear chains of short ZnO nanorods embedded in MgO nanotubes and porous MgO nanotubes can be obtained by taking advantage of the reduced thermal stability of the ZnO core. Furthermore, after MgO shell-coating and the appropriate annealing treatment, the intensity of the ZnO near-band-edge UV emission becomes much stronger, showing a 25-fold enhancement. The intensity ratio of the UV/visible emission can be increased further by decorating the surface of the ZnO/MgO nanowires with high-density plasmonic Au nanoparticles. These heterostructured semiconductor-insulator-metal nanowires with tailored morphologies and enhanced functionalities have great potential for use as nanoscale building blocks in photonic and electronic applications.Controllably constructing hierarchical nanostructures with distinct components and designed architectures is an important theme of research in nanoscience, entailing novel but reliable approaches of bottom-up synthesis. Here, we report a facile method to reproducibly create semiconductor-insulator-metal core/shell nanostructures, which involves first coating uniform MgO shells onto metal oxide nanostructures in solution and then decorating them with Au nanoparticles. The semiconductor nanowire core can be almost any material and, herein, ZnO, SnO2 and In2O3 are used as examples. We also show that linear chains of short ZnO nanorods embedded in MgO nanotubes and porous MgO nanotubes can be obtained by taking advantage of the reduced thermal stability of the ZnO core. Furthermore, after MgO shell-coating and the appropriate annealing treatment, the intensity of the ZnO near-band-edge UV emission becomes much stronger, showing a 25-fold enhancement. The intensity ratio of the UV/visible emission can be increased further by decorating the surface of the ZnO/MgO nanowires with high-density plasmonic Au nanoparticles. These heterostructured semiconductor-insulator-metal nanowires with tailored morphologies and enhanced functionalities have great potential for use as nanoscale building blocks in photonic and electronic applications. Electronic supplementary information (ESI) available: Representative SEM and TEM images of 700 °C annealed ZnO/MgO core/shell NWs, a TEM image of an individual MgO nanocrystal inside the MgO NTs and SEM images of SnO2 NP chains embedded in MgO NTs and comb-shaped MgO hollow nanostructures. See DOI: 10.1039/c1nr10352k

Limonia acidissima L. leaf mediated synthesis of zinc oxide nanoparticles: A potent tool against Mycobacterium tuberculosis.

PubMed

Taranath, Tarikere C; Patil, Bheemanagouda N

2016-06-01

The present investigation was undertaken to synthesize zinc oxide nanoparticles using Limonia acidissima L. and to test their efficacy against the growth of Mycobacterium tuberculosis. The formation of zinc oxide nanoparticles was confirmed with UV-visible spectrophotometry. Fourier transform infrared spectroscopy shows the presence of bio-molecules involved in the stabilization of zinc oxide nanoparticles. The shape and size was confirmed with atomic force microscope, X-ray diffraction, and high resolution transmission electron microscope. These nanoparticles were tested for their effect on the growth of M. tuberculosis through the microplate alamar blue assay technique. The UV-visible data reveal that an absorbance peak at 374nm confirms formation of zinc oxide nanoparticles and they are spherical in shape with sizes between 12nm and 53nm. These nanoparticles control the growth of M. tuberculosis at 12.5μg/mL. Phytosynthesis of zinc oxide nanoparticles is a green, eco-friendly technology because it is inexpensive and pollution free. In the present investigation, based on our results we conclude that the aqueous extract of leaves of L. acidissima can be used for the synthesis of zinc oxide nanoparticles. These nanoparticles control the growth of M. tuberculosis and this was confirmed with the microplate alamar blue method. The potential of biogenic zinc oxide nanoparticles may be harnessed as a novel medicine ingredient to combat tuberculosis disease. Copyright © 2016 Asian-African Society for Mycobacteriology. Published by Elsevier Ltd. All rights reserved.

Laser-Induced, Local Oxidation of Copper Nanoparticle Films During Raman Measurements

NASA Astrophysics Data System (ADS)

Hight Walker, Angela R.; Cheng, Guangjun; Calizo, Irene

2011-03-01

The optical properties of gold and silver nanoparticles and their films have been thoroughly investigated as surface enhanced Raman scattering (SERS) substrates and chemical reaction promoters. Similar to gold and silver nanoparticles, copper nanoparticles exhibit distinct plasmon absorptions in the visible region. The work on copper nanoparticles and their films is limited due to their oxidization in air. However, their high reactivity actually provides an opportunity to exploit the laser-induced thermal effect and chemical reactions of these nanoparticles. Here, we present our investigation of the local oxidation of a copper nanoparticle film induced by a visible laser source during Raman spectroscopic measurements. The copper nanoparticle film is prepared by drop-casting chemically synthesized copper colloid onto silicon oxide/silicon substrate. The local oxidation induced by visible lasers in Raman spectroscopy is monitored with the distinct scattering peaks for copper oxides. Optical microscopy and scanning electron microscopy have been used to characterize the laser-induced morphological changes in the film. The results of this oxidation process with different excitation wavelengths and different laser powers will be presented.

Nickel oxide nanoparticles film produced by dead biomass of filamentous fungus

PubMed Central

Salvadori, Marcia Regina; Nascimento, Cláudio Augusto Oller; Corrêa, Benedito

2014-01-01

The synthesis of nickel oxide nanoparticles in film form using dead biomass of the filamentous fungus Aspergillus aculeatus as reducing agent represents an environmentally friendly nanotechnological innovation. The optimal conditions and the capacity of dead biomass to uptake and produce nanoparticles were evaluated by analyzing the biosorption of nickel by the fungus. The structural characteristics of the film-forming nickel oxide nanoparticles were analyzed by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and atomic force microscopy (AFM). These techniques showed that the nickel oxide nanoparticles had a size of about 5.89 nm and were involved in a protein matrix which probably permitted their organization in film form. The production and uptake of nickel oxide nanoparticles organized in film form by dead fungal biomass bring us closer to sustainable strategies for the biosynthesis of metal oxide nanoparticles. PMID:25228324

Palladium-Zeolite nanofiber as an effective recyclable catalyst membrane for water treatment.

PubMed

Choi, Jungsu; Chan, Sophia; Yip, Garriott; Joo, Hyunjong; Yang, Heejae; Ko, Frank K

2016-09-15

Zeolite is an exciting natural material due to its unique capability of ammonium nitrogen (NH3N) adsorption in water. In this study, multifunctional hybrid composites of zeolite/palladium (Ze/Pd) on polymer nanofiber membranes were fabricated and explored for sustainable contaminant removal. SEM and XRD demonstrated that zeolite and palladium nanoparticles were uniformly distributed and deposited on the nanofibers. NH3N recovery rate was increased from 23 to 92% when palladium coated zeolite was embedded on the nanofiber. Multifunctional nanofibers of Ze/Pd membranes were able to adsorb NH3N on the zeolites placed on the surface of fibers and palladium catalysts were capable of selective oxidation of NH3N to N2 gas. The cycling of NH3N adsorption-oxidation, high flux, hydrophilicity, and flexibility of the membrane makes it a strong candidate for water treatment. Copyright © 2016 Elsevier Ltd. All rights reserved.

Preparation and evaluation of poly(2-hydroxyethyl aspartamide)-hexadecylamine-iron oxide for MR imaging of lymph nodes

PubMed Central

2014-01-01

The purpose of this study was to synthesize biocompatible poly(2-hydroxyethyl aspartamide)–C16-iron oxide (PHEA-C16-iron oxide) nanoparticles and to evaluate their efficacy as a contrast agent for magnetic resonance imaging of lymph nodes. The PHEA-C16-iron oxide nanoparticles were synthesized by coprecipitation method. The core size of the PHEA-C16-iron oxide nanoparticles was about 5 to 7 nm, and the overall size of the nanoparticles was around 20, 60, and 150 nm in aqueous solution. The size of the nanoparticles was controlled by the amount of C16. The 3.0-T MRI signal intensity of a rabbit lymph node was effectively reduced after intravenous administration of PHEA-C16-iron oxide with the size of 20 nm. The in vitro and in vivo toxicity tests revealed the high biocompatibility of PHEA-C16-iron oxide nanoparticles. Therefore, PHEA-C16-iron oxide nanoparticles with 20-nm size can be potentially useful as T2-weighted MR imaging contrast agents for the detection of lymph nodes. PMID:24438671

A comparative ecotoxicity analysis of α- and γ-phase aluminium oxide nanoparticles towards a freshwater bacterial isolate Bacillus licheniformis.

PubMed

Pakrashi, Sunandan; Kumar, Deepak; Iswarya, V; Bhuvaneshwari, M; Chandrasekaran, N; Mukherjee, Amitava

2014-12-01

Crystalline structure of nanoparticles may influence their physicochemical behaviour as well as their toxicological impact on biota. The differences in orientation of the atoms result in the variations in chemical stability. Thus, toxicological impacts of different crystalline phases of aluminium oxide nanoparticles are expected to vary. The present study brings out a comparative toxicity analysis of γ-phase and α-phase aluminium oxide nanoparticles of comparable hydrodynamic size range towards a freshwater bacterial isolate Bacillus licheniformis at low exposure concentrations (5, 1, 0.5 and 0.05 µg/mL). Upon 2-h exposure, the α-aluminium oxide particles showed lower toxicity than the γ-phase aluminium oxide. The lower level of oxidative stress generation and cell membrane damage in case of the α-phase aluminium oxide nanoparticles substantiated the toxicity results. The involvement of protein, lipopolysaccharides in nanoparticle-cell surface interaction, was noted in both the cases. To conclude, the crystallinity of aluminium oxide nanoparticles played an important role in the interaction and the toxicity response.

Engineering the defect state and reducibility of ceria based nanoparticles for improved anti-oxidation performance

NASA Astrophysics Data System (ADS)

Wang, Yan-Jie; Dong, Hao; Lyu, Guang-Ming; Zhang, Huai-Yuan; Ke, Jun; Kang, Li-Qun; Teng, Jia-Li; Sun, Ling-Dong; Si, Rui; Zhang, Jing; Liu, Yan-Jun; Zhang, Ya-Wen; Huang, Yun-Hui; Yan, Chun-Hua

2015-08-01

Due to their excellent anti-oxidation performance, CeO2 nanoparticles receive wide attention in pharmacological application. Deep understanding of the anti-oxidation mechanism of CeO2 nanoparticles is extremely important to develop potent CeO2 nanomaterials for anti-oxidation application. Here, we report a detailed study on the anti-oxidation process of CeO2 nanoparticles. The valence state and coordination structure of Ce are characterized before and after the addition of H2O2 to understand the anti-oxidation mechanism of CeO2 nanoparticles. Adsorbed peroxide species are detected during the anti-oxidation process, which are responsible for the red-shifted UV-vis absorption spectra of CeO2 nanoparticles. Furthermore, the coordination number of Ce in the first coordination shell slightly increased after the addition of H2O2. On the basis of these experimental results, the reactivity of coordination sites for peroxide species is considered to play a key role in the anti-oxidation performance of CeO2 nanoparticles. Furthermore, we present a robust method to engineer the anti-oxidation performance of CeO2 nanoparticles through the modification of the defect state and reducibility by doping with Gd3+. Improved anti-oxidation performance is also observed in cell culture, where the biocompatible CeO2-based nanoparticles can protect INS-1 cells from oxidative stress induced by H2O2, suggesting the potential application of CeO2 nanoparticles in the treatment of diabetes.Due to their excellent anti-oxidation performance, CeO2 nanoparticles receive wide attention in pharmacological application. Deep understanding of the anti-oxidation mechanism of CeO2 nanoparticles is extremely important to develop potent CeO2 nanomaterials for anti-oxidation application. Here, we report a detailed study on the anti-oxidation process of CeO2 nanoparticles. The valence state and coordination structure of Ce are characterized before and after the addition of H2O2 to understand the anti-oxidation mechanism of CeO2 nanoparticles. Adsorbed peroxide species are detected during the anti-oxidation process, which are responsible for the red-shifted UV-vis absorption spectra of CeO2 nanoparticles. Furthermore, the coordination number of Ce in the first coordination shell slightly increased after the addition of H2O2. On the basis of these experimental results, the reactivity of coordination sites for peroxide species is considered to play a key role in the anti-oxidation performance of CeO2 nanoparticles. Furthermore, we present a robust method to engineer the anti-oxidation performance of CeO2 nanoparticles through the modification of the defect state and reducibility by doping with Gd3+. Improved anti-oxidation performance is also observed in cell culture, where the biocompatible CeO2-based nanoparticles can protect INS-1 cells from oxidative stress induced by H2O2, suggesting the potential application of CeO2 nanoparticles in the treatment of diabetes. Electronic supplementary information (ESI) available: Size distribution of prepared CeO2-based NPs, HRTEM of prepared CeO2-based NPs, XPS analysis of prepared CeO2-based NPs, EELS analysis of prepared CeO2-based NPs, TG curves and FT-IR spectra of CeO2-based NPs, XANES spectra of CeO2 NPs during the reaction with H2O2, Raman spectrum of CeO2 NPs during the reaction with H2O2 for the second and third cycle, ESR analysis during the reaction, the red shift of UV-vis spectra of CeO2-based NPs after the addition of H2O2, H2-TPR test of CeO2 and CeO2:20%Gd NPs, In vitro cytotoxicity of CeO2-based NPs in INS-1 cells. See DOI: 10.1039/c5nr02588e

Comparative Proteomic Analysis of the Molecular Responses of Mouse Macrophages to Titanium Dioxide and Copper Oxide Nanoparticles Unravels Some Toxic Mechanisms for Copper Oxide Nanoparticles in Macrophages

PubMed Central

Triboulet, Sarah; Aude-Garcia, Catherine; Armand, Lucie; Collin-Faure, Véronique; Chevallet, Mireille; Diemer, Hélène; Gerdil, Adèle; Proamer, Fabienne; Strub, Jean-Marc; Habert, Aurélie; Herlin, Nathalie; Van Dorsselaer, Alain; Carrière, Marie; Rabilloud, Thierry

2015-01-01

Titanium dioxide and copper oxide nanoparticles are more and more widely used because of their catalytic properties, of their light absorbing properties (titanium dioxide) or of their biocidal properties (copper oxide), increasing the risk of adverse health effects. In this frame, the responses of mouse macrophages were studied. Both proteomic and targeted analyses were performed to investigate several parameters, such as phagocytic capacity, cytokine release, copper release, and response at sub toxic doses. Besides titanium dioxide and copper oxide nanoparticles, copper ions were used as controls. We also showed that the overall copper release in the cell does not explain per se the toxicity observed with copper oxide nanoparticles. In addition, both copper ion and copper oxide nanoparticles, but not titanium oxide, induced DNA strands breaks in macrophages. As to functional responses, the phagocytic capacity was not hampered by any of the treatments at non-toxic doses, while copper ion decreased the lipopolysaccharide-induced cytokine and nitric oxide productions. The proteomic analyses highlighted very few changes induced by titanium dioxide nanoparticles, but an induction of heme oxygenase, an increase of glutathione synthesis and a decrease of tetrahydrobiopterin in response to copper oxide nanoparticles. Subsequent targeted analyses demonstrated that the increase in glutathione biosynthesis and the induction of heme oxygenase (e.g. by lovastatin/monacolin K) are critical for macrophages to survive a copper challenge, and that the intermediates of the catecholamine pathway induce a strong cross toxicity with copper oxide nanoparticles and copper ions. PMID:25902355

Preparation and characterization of copper oxide nanoparticles decorated carbon nanoparticles using laser ablation in liquid

NASA Astrophysics Data System (ADS)

Khashan, K. S.; Jabir, M. S.; Abdulameer, F. A.

2018-05-01

Carbon nanoparticles CNPs ecorated by copper oxide nano-sized particles would be successfully equipped using technique named pulsed laser ablation in liquid. The XRD pattern proved the presence of phases assigned to carbon and different phases of copper oxide. The chemical structure of the as-prepared nanoparticles samples was decided by Energy Dispersive Spectrum (EDS) measurement. EDS analysis results show the contents of Carbon, Oxygen and Copper in the final product. These nanoparticles were spherical shaped with a size distribution 10 to 80 nm or carbon nanoparticles and 5 to 50 nm for carbon decorated copper oxide nanoparticles, according to Transmission Electron Microscopy (TEM) images and particle-size distribution histogram. It was found that after doping with copper oxide, nanoparticles become smaller and more regular in shape. Optical absorption spectra of prepared nanoparticles were measured using UV–VIS spectroscopy. The absorption spectrum of carbon nanoparticles without doping indicates absorption peak at about 228 nm. After doping with copper oxide, absorption shows appearance of new absorption peak at about (254-264) nm, which is referred to the movement of the charge between 2p and 4s band of Cu2+ ions.

Ultrasmall water-soluble metal-iron oxide nanoparticles as T1-weighted contrast agents for magnetic resonance imaging.

PubMed

Zeng, Leyong; Ren, Wenzhi; Zheng, Jianjun; Cui, Ping; Wu, Aiguo

2012-02-28

Using an improved hydrolysis method of inorganic salts assisted with water-bath incubation, ultrasmall water-soluble metal-iron oxide nanoparticles (including Fe(3)O(4), ZnFe(2)O(4) and NiFe(2)O(4) nanoparticles) were synthesized in aqueous solutions, which were used as T(1)-weighted contrast agents for magnetic resonance imaging (MRI). The morphology, structure, MRI relaxation properties and cytotoxicity of the as-prepared metal-iron oxide nanoparticles were characterized, respectively. The results showed that the average sizes of nanoparticles were about 4 nm, 4 nm and 5 nm for Fe(3)O(4), ZnFe(2)O(4) and NiFe(2)O(4) nanoparticles, respectively. Moreover, the nanoparticles have good water dispersibility and low cytotoxicity. The MRI test showed the strong T(1)-weighted, but the weak T(2)-weighted MRI performance of metal-iron oxide nanoparticles. The high T(1)-weighted MRI performance can be attributed to the ultrasmall size of metal-iron oxide nanoparticles. Therefore, the as-prepared metal-iron oxide nanoparticles with good water dispersibility and ultrasmall size can have potential applications as T(1)-weighted contrast agent materials for MRI.

Plasmonic activity on gold nanoparticles embedded in nanopores formed in a surface layer of silica glass by swift-heavy-ion irradiation.

PubMed

Nomura, Ken-ichi; Ohki, Yoshimichi; Fujimaki, Makoto; Wang, Xiaomin; Awazu, Koichi; Komatsubara, Tetsuro

2009-11-25

Silica glass was irradiated by swift heavy ions by selecting the ion species and its energy in order to induce the largest damaged regions. These regions were then selectively etched by hydrofluoric acid vapour to form nanopores on the glass surface. Subsequently, gold nanoparticles were embedded into the nanopores by vacuum evaporation, followed by thermal treatment. In the new plasmonic structure obtained with these procedures, the localized surface plasmon excitation wavelength induced around the gold nanoparticles was found to show a redshift, which agreed well with the theoretical calculation, when water was introduced into the nanopores. This indicates that the fabricated structure can be used as a sensing element to detect the adhesion of substances such as biomolecules to the nanoparticles by measuring the redshift.

Fabrication and characterization of biological tissue phantoms with embedded nanoparticles

NASA Astrophysics Data System (ADS)

Skaptsov, A. A.; Ustalkov, S. O.; Mohammed, A. H. M.; Savenko, O. A.; Novikova, A. S.; Kozlova, E. A.; Kochubey, V. I.

2017-11-01

Phantoms are imitations of biological tissue, which are used for modelling of the light propagation in biological tissues. Carrying out any biophysical experiments requires an indispensable constancy of the initial experiment conditions. The use of solid undegradable phantoms is the basis to obtain reliable reproducible experimental results. The fabrication of biological tissues phantoms containing high absorbance or fluorescence nanoparticles and corresponding to specific mechanical, optical properties is an actual task. This work describes development, fabrication and characterization of such solid tissue phantoms with embedded CdSe/ZnS quantum dots, gold and upconversion nanoparticles. Luminescence of samples with CdSe/ZnS quantum dots and upconversion nanoparticles were recorded. A sample of gold nanorods was analyzed using thermal gravimetric analysis. It can be concluded that the samples are well suited for experiments on laser thermolysis.

Electrical bistabilities and memory mechanisms of nonvolatile organic bistable devices based on exfoliated muscovite-type mica nanoparticle/poly(methylmethacrylate) nanocomposites

NASA Astrophysics Data System (ADS)

Lim, Won Gyu; Lee, Dea Uk; Na, Han Gil; Kim, Hyoun Woo; Kim, Tae Whan

2018-02-01

Organic bistable devices (OBDs) with exfoliated mica nanoparticles (NPs) embedded into an insulating poly(methylmethacrylate) (PMMA) layer were fabricated by using a spin-coating method. Current-voltage (I-V) curves for the Al/PMMA/exfoliated mica NP/PMMA/indium-tin-oxide/glass devices at 300 K showed a clockwise current hysteresis behavior due to the existence of the exfoliated muscovite-type mica NPs, which is an essential feature for bistable devices. Write-read-erase-read data showed that the OBDs had rewritable nonvolatile memories and an endurance number of ON/OFF switching for the OBDs of 102 cycles. An ON/OFF ratio of 1 × 103 was maintained for retention times larger than 1 × 104 s. The memory mechanisms of the fabricated OBDs were described by using the trapping and the tunneling processes within a PMMA active layer containing exfoliated muscovite-type mica NPs on the basis of the energy band diagram and the I-V curves.

Targeted Mesoporous Iron Oxide Nanoparticles-Encapsulated Perfluorohexane and a Hydrophobic Drug for Deep Tumor Penetration and Therapy.

PubMed

Su, Yu-Lin; Fang, Jen-Hung; Liao, Chia-Ying; Lin, Chein-Ting; Li, Yun-Ting; Hu, Shang-Hsiu

2015-01-01

A magneto-responsive energy/drug carrier that enhances deep tumor penetration with a porous nano-composite is constructed by using a tumor-targeted lactoferrin (Lf) bio-gate as a cap on mesoporous iron oxide nanoparticles (MIONs). With a large payload of a gas-generated molecule, perfluorohexane (PFH), and a hydrophobic anti-cancer drug, paclitaxel (PTX), Lf-MIONs can simultaneously perform bursting gas generation and on-demand drug release upon high-frequency magnetic field (MF) exposure. Biocompatible PFH was chosen and encapsulated in MIONs due to its favorable phase transition temperature (56 °C) and its hydrophobicity. After a short-duration MF treatment induces heat generation, the local pressure increase via the gasifying of the PFH embedded in MION can substantially rupture the three-dimensional tumor spheroids in vitro as well as enhance drug and carrier penetration. As the MF treatment duration increases, Lf-MIONs entering the tumor spheroids provide an intense heat and burst-like drug release, leading to superior drug delivery and deep tumor thermo-chemo-therapy. With their high efficiency for targeting tumors, Lf-MIONs/PTX-PFH suppressed subcutaneous tumors in 16 days after a single MF exposure. This work presents the first study of using MF-induced PFH gasification as a deep tumor-penetrating agent for drug delivery.

Targeted Mesoporous Iron Oxide Nanoparticles-Encapsulated Perfluorohexane and a Hydrophobic Drug for Deep Tumor Penetration and Therapy

PubMed Central

Su, Yu-Lin; Fang, Jen-Hung; Liao, Chia-Ying; Lin, Chein-Ting; Li, Yun-Ting; Hu, Shang-Hsiu

2015-01-01

A magneto-responsive energy/drug carrier that enhances deep tumor penetration with a porous nano-composite is constructed by using a tumor-targeted lactoferrin (Lf) bio-gate as a cap on mesoporous iron oxide nanoparticles (MIONs). With a large payload of a gas-generated molecule, perfluorohexane (PFH), and a hydrophobic anti-cancer drug, paclitaxel (PTX), Lf-MIONs can simultaneously perform bursting gas generation and on-demand drug release upon high-frequency magnetic field (MF) exposure. Biocompatible PFH was chosen and encapsulated in MIONs due to its favorable phase transition temperature (56 °C) and its hydrophobicity. After a short-duration MF treatment induces heat generation, the local pressure increase via the gasifying of the PFH embedded in MION can substantially rupture the three-dimensional tumor spheroids in vitro as well as enhance drug and carrier penetration. As the MF treatment duration increases, Lf-MIONs entering the tumor spheroids provide an intense heat and burst-like drug release, leading to superior drug delivery and deep tumor thermo-chemo-therapy. With their high efficiency for targeting tumors, Lf-MIONs/PTX-PFH suppressed subcutaneous tumors in 16 days after a single MF exposure. This work presents the first study of using MF-induced PFH gasification as a deep tumor-penetrating agent for drug delivery. PMID:26379789

Crab-shell induced synthesis of ordered macroporous carbon nanofiber arrays coupled with MnCo2O4 nanoparticles as bifunctional oxygen catalysts for rechargeable Zn-air batteries.

PubMed

Bin, Duan; Guo, Ziyang; Tamirat, Andebet Gedamu; Ma, Yuanyuan; Wang, Yonggang; Xia, Yongyao

2017-08-10

The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are traditionally carried out using noble metals (such as Pt) and metal oxides (such as RuO 2 and IrO 2 ) as catalysts, respectively. Nevertheless, several key issues such as high cost, poor stability, and detrimental environmental effects limit the catalytic activity of these noble metal- and metal oxide-based catalysts. Herein, we have designed and synthesized macroporous carbon nanofiber arrays by using a natural crab shell template. Subsequently, spinel MnCo 2 O 4 nanoparticles were embedded into the nitrogen-doped macroporous carbon nanofiber arrays (NMCNAs) by a hydrothermal method. Accompanied by the good conductivity, large surface area and doping of nitrogen, the as-prepared MnCo 2 O 4 /NMCNA exhibited remarkable catalytic performance and outstanding stability for both ORR and OER in alkaline media. The macroporous superstructures play vital role in reducing the ion transport resistance and facilitating the diffusion of gaseous products (O 2 ). Finally, rechargeable Zn-air batteries using the MnCo 2 O 4 /NMCNA catalyst displayed appreciably lower overpotentials, higher power density and better stability than commercial Pt/C, thus raising the prospect of functional low-cost, non-precious-metal bifunctional catalysts in metal-air batteries.

A facile one-pot self-assembly approach to incorporate SnOx nanoparticles in ordered mesoporous carbon with soft templating for fuel cells.

PubMed

Huang, Yingqiang; Zhai, Zhicheng; Luo, Zhigang; Liu, Yingju; Liang, Zhurong; Fang, Yueping

2014-04-04

Unique SnO(x) (x = 1,2)/ordered mesoporous carbon nanocomposites (denoted as SnO(x)/OMC) are firstly synthesized through a 'one-pot' synthesis together with the soft template self-assembly approach. The obtained SnO(x)/OMC nanocomposites with various SnO(x) contents exhibit uniform pore sizes between 3.9 and 4.2 nm, high specific surface areas between 497 and 595 m(2) g(-1), and high pore volumes between 0.39 and 0.48 cm(3) g(-1). With loading of Pt, Pt-SnO(x)/OMC with relatively low SnO(x) content exhibits superior electrocatalytic performance, long-term durability, and resistance to CO poisoning for methanol oxidation, as compared to Pt/OMC, PtRu/C and Pt-SnO(x)/C, which may be attributed not only to the synergetic effect of embedded SnO(x), but also to the highly ordered mesostructure with high specific surface areas and large pore volumes affording plenty of surface area for support of Pt nanoparticles. This work supplies an efficient way to synthesize novel ordered mesoporous carbon self-supported metallic oxide as catalyst support and its further potential application to reduce the cost of catalysts in direct methanol fuel cells.

A facile one-pot self-assembly approach to incorporate SnOx nanoparticles in ordered mesoporous carbon with soft templating for fuel cells

NASA Astrophysics Data System (ADS)

Huang, Yingqiang; Zhai, Zhicheng; Luo, Zhigang; Liu, Yingju; Liang, Zhurong; Fang, Yueping

2014-04-01

Unique SnOx (x = 1,2)/ordered mesoporous carbon nanocomposites (denoted as SnOx/OMC) are firstly synthesized through a ‘one-pot’ synthesis together with the soft template self-assembly approach. The obtained SnOx/OMC nanocomposites with various SnOx contents exhibit uniform pore sizes between 3.9 and 4.2 nm, high specific surface areas between 497 and 595 m2 g-1, and high pore volumes between 0.39 and 0.48 cm3 g-1. With loading of Pt, Pt-SnOx/OMC with relatively low SnOx content exhibits superior electrocatalytic performance, long-term durability, and resistance to CO poisoning for methanol oxidation, as compared to Pt/OMC, PtRu/C and Pt-SnOx/C, which may be attributed not only to the synergetic effect of embedded SnOx, but also to the highly ordered mesostructure with high specific surface areas and large pore volumes affording plenty of surface area for support of Pt nanoparticles. This work supplies an efficient way to synthesize novel ordered mesoporous carbon self-supported metallic oxide as catalyst support and its further potential application to reduce the cost of catalysts in direct methanol fuel cells.

Targeted iron oxide nanoparticles for the enhancement of radiation therapy.

PubMed

Hauser, Anastasia K; Mitov, Mihail I; Daley, Emily F; McGarry, Ronald C; Anderson, Kimberly W; Hilt, J Zach

2016-10-01

To increase the efficacy of radiation, iron oxide nanoparticles can be utilized for their ability to produce reactive oxygen species (ROS). Radiation therapy promotes leakage of electrons from the electron transport chain and leads to an increase in mitochondrial production of the superoxide anion which is converted to hydrogen peroxide by superoxide dismutase. Iron oxide nanoparticles can then catalyze the reaction from hydrogen peroxide to the highly reactive hydroxyl radical. Therefore, the overall aim of this project was to utilize iron oxide nanoparticles conjugated to a cell penetrating peptide, TAT, to escape lysosomal encapsulation after internalization by cancer cells and catalyze hydroxyl radical formation. It was determined that TAT functionalized iron oxide nanoparticles and uncoated iron oxide nanoparticles resulted in permeabilization of the lysosomal membranes. Additionally, mitochondrial integrity was compromised when A549 cells were treated with both TAT-functionalized nanoparticles and radiation. Pre-treatment with TAT-functionalized nanoparticles also significantly increased the ROS generation associated with radiation. A long term viability study showed that TAT-functionalized nanoparticles combined with radiation resulted in a synergistic combination treatment. This is likely due to the TAT-functionalized nanoparticles sensitizing the cells to subsequent radiation therapy, because the nanoparticles alone did not result in significant toxicities. Copyright © 2016 Elsevier Ltd. All rights reserved.

Embedment of silver into temperature- and pH-responsive microgel for the development of smart textiles with simultaneous moisture management and controlled antimicrobial activities.

PubMed

Štular, Danaja; Jerman, Ivan; Naglič, Iztok; Simončič, Barbara; Tomšič, Brigita

2017-03-01

Silver nanoparticles were embedded into a temperature- and pH-responsive microgel based on poly-(N-isopropylacrylamide) and chitosan (PNCS) before or after its application to cotton fabric to create a smart stimuli-responsive textile with simultaneous moisture management and controlled antimicrobial activities. Two different methods of silver embedment into the PNCS microgel using two different forms of silver nanoparticles were studied, i.e., in-situ synthesis of AgCl nanocrystals into PNCS microgel particles that had previously been applied to cotton fabric, as well as the direct incorporation of colloidal silver into the microgel suspension prior to its deposition on cellulose fibres. SEM and FT-IR analysis were employed to determine the morphological and chemical changes of the modified cotton fibres, while EDS and ICP MS analysis were used to confirm the presence of the silver nanoparticles. The influence of silver embedment on the swelling/deswelling activity of the PNCS microgel was studied using the temperature- and pH-responsiveness, as determined by the moisture content, water vapour transmission rate and water uptake. The antimicrobial activity against the bacteria Staphylococcus aureus and Escherichia coli was assessed. Regardless of the embedment technique, the presence of silver nanoparticles resulted in impaired moisture management activity of the studied microgel. The PNCS microgel proved to be a suitable carrier of antimicrobial agents, assuring the effective controlled release of silver triggered by changes in the temperature and pH of the surroundings, which granted the cotton fabric excellent antimicrobial activity against Gram-negative E. coli (>99%) and Gram-positive S. aureus (>85%). Copyright © 2016 Elsevier Ltd. All rights reserved.

A Study on Dielectric Properties of Cadmium Sulfide-Zinc Sulfide Core-Shell Nanocomposites for Application as Nanoelectronic Filter Component in the Microwave Domain

NASA Astrophysics Data System (ADS)

Devi, Jutika; Datta, Pranayee

2018-07-01

Complex permittivities of cadmium sulfide (CdS), zinc sulfide (ZnS), and of cadmium sulfide-zinc sulfide (CdS/ZnS) core-shell nanoparticles embedded in a polyvinyl alcohol matrix (PVA) were measured in liquid phase using a VectorNetwork Analyzer in the frequency range of 500 MHz-10 GHz. These nanocomposites are modeled as an embedded capacitor, and their electric field distribution and polarization have been studied using COMSOL Multiphysics software. By varying the thickness of the shell and the number of inclusions, the capacitance values were estimated. It was observed that CdS, ZnS and CdS/ZnS core-shell nanoparticles embedded in a polyvinyl alcohol matrix show capacitive behavior. There is a strong influence of the dielectric properties in the capacitive behavior of the embedded nanocapacitor. The capping matrix, position and filling factors of nanoinclusions all affect the capacitive behavior of the tested nanocomposites. Application of the CdS, ZnS and CdS/ZnS core-shell nanocomposite as the passive low-pass filter circuit has also been investigated. From the present study, it has been found that CdS/ZnS core-shell nanoparticles embedded in PVA matrix are potential structures for application as nanoelectronic filter components in different areas of communication.

A Study on Dielectric Properties of Cadmium Sulfide-Zinc Sulfide Core-Shell Nanocomposites for Application as Nanoelectronic Filter Component in the Microwave Domain

NASA Astrophysics Data System (ADS)

Devi, Jutika; Datta, Pranayee

2018-03-01

Complex permittivities of cadmium sulfide (CdS), zinc sulfide (ZnS), and of cadmium sulfide-zinc sulfide (CdS/ZnS) core-shell nanoparticles embedded in a polyvinyl alcohol matrix (PVA) were measured in liquid phase using a VectorNetwork Analyzer in the frequency range of 500 MHz-10 GHz. These nanocomposites are modeled as an embedded capacitor, and their electric field distribution and polarization have been studied using COMSOL Multiphysics software. By varying the thickness of the shell and the number of inclusions, the capacitance values were estimated. It was observed that CdS, ZnS and CdS/ZnS core-shell nanoparticles embedded in a polyvinyl alcohol matrix show capacitive behavior. There is a strong influence of the dielectric properties in the capacitive behavior of the embedded nanocapacitor. The capping matrix, position and filling factors of nanoinclusions all affect the capacitive behavior of the tested nanocomposites. Application of the CdS, ZnS and CdS/ZnS core-shell nanocomposite as the passive low-pass filter circuit has also been investigated. From the present study, it has been found that CdS/ZnS core-shell nanoparticles embedded in PVA matrix are potential structures for application as nanoelectronic filter components in different areas of communication.

Evaluation of antioxidant and anticancer activity of copper oxide nanoparticles synthesized using medicinally important plant extracts.

PubMed

Rehana, Dilaveez; Mahendiran, D; Kumar, R Senthil; Rahiman, A Kalilur

2017-05-01

Copper oxide (CuO) nanoparticles were synthesized by green chemistry approach using different plant extracts obtained from the leaves of Azadirachta indica, Hibiscus rosa-sinensis, Murraya koenigii, Moringa oleifera and Tamarindus indica. In order to compare their efficiency, the same copper oxide nanoparticles was also synthesized by chemical method. Phytochemical screening of the leaf extracts showed the presence of carbohydrates, flavonoids, glycosides, phenolic compounds, saponins, tannins, proteins and amino acids. FT IR spectra confirmed the possible biomolecules responsible for the formation of copper oxide nanoparticles. The surface plasmon resonance absorption band at 220-235nm in the UV-vis spectra also supports the formation of copper oxide nanoparticles. XRD patterns revealed the monoclinic phase of the synthesized copper oxide nanoparticles. The average size, shape and the crystalline nature of the nanoparticles were determined by SEM, TEM and SAED analysis. EDX analysis confirmed the presence of elements in the synthesized nanoparticles. The antioxidant activity was evaluated by three different free radical scavenging assays. The cytotoxicity of copper oxide nanoparticles was evaluated against four cancer cell lines such as human breast (MCF-7), cervical (HeLa), epithelioma (Hep-2) and lung (A549), and one normal human dermal fibroblast (NHDF) cell line. The morphological changes were evaluated using Hoechst 33258 staining assay. Copper oxide nanoparticles synthesized by green method exhibited high antioxidant and cytotoxicity than that synthesized by chemical method. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Magnetic cobaltic nanoparticle-anchored carbon nanocomposite derived from cobalt-dipicolinic acid coordination polymer: An enhanced catalyst for environmental oxidative and reductive reactions.

PubMed

Wu, Chang-Hsun; Lin, Jyun-Ting; Lin, Kun-Yi Andrew

2018-05-01

Direct carbonization of cobalt complexes represents as a convenient approach to prepare magnetic carbon/cobalt nanocomposites (MCCNs) as heterogeneous environmental catalysts. However, most of MCCNs derived from consist of sheet-like carbon matrices with very sparse cobaltic nanoparticles (NPs), making them exhibit relatively low catalytic activities, porosity and magnetism. In this study, dipicolinic acid (DPA) is selected to prepare a 3-dimensional cobalt coordination polymer (CoDPA). MCCN derived from CoDPA can consist of a porous carbon matrix embedded with highly-dense Co 0 and Co 3 O 4 NPs. This magnetic Co 0 /Co 3 O 4 NP-anchored carbon composite (MCNC) appears as a promising heterogeneous catalyst for oxidative and reductive environmental catalytic reactions. As peroxymonosulfate (PMS) activation is selected as a model catalytic oxidative reaction, MCNC exhibits a much higher catalytic activity than Co 3 O 4 , a benchmark catalyst for PMS activation. The reductive catalytic activity of MCNC is demonstrated through 4-nitrophenol (4-NP) reduction in the presence of NaBH 4 . MCNC could rapidly react with NaBH 4 to generate H 2 for hydrogenation of 4-NP to 4-aminophenol (4-AP). In comparison with other precious metallic catalysts, MCNC also shows a relatively high catalytic activity. These results indicate that MCNC is a conveniently prepared and highly effective and stable carbon-supported cobaltic heterogeneous catalyst for versatile environmental catalytic applications. Copyright © 2018 Elsevier Inc. All rights reserved.

Determination of the thickness of the embedding phase in 0D nanocomposites

NASA Astrophysics Data System (ADS)

Martínez-Martínez, D.; Sánchez-López, J. C.

2017-11-01

0D nanocomposites formed by small nanoparticles embedded in a second phase are very interesting systems which may show properties that are beyond those observed in the original constituents alone. One of the main parameters to understand the behavior of such nanocomposites is the determination of the separation between two adjacent nanoparticles, in other words, the thickness of the embedding phase. However, its experimental measurement is extremely complicated. Therefore, its evaluation is performed by an indirect approach using geometrical models. The ones typically used represent the nanoparticles by cubes or spheres. In this paper the used geometrical models are revised, and additional geometrical models based in other parallelohedra (hexagonal prism, rhombic and elongated dodecahedron and truncated octahedron) are presented. Additionally, a hybrid model that shows a transition between the spherical and tessellated models is proposed. Finally, the different approaches are tested on a set of titanium carbide/amorphous carbon (TiC/a-C) nanocomposite films to estimate the thickness of the a-C phase and explain the observed hardness properties.

Copper Oxide Nanoparticles Impact Several Toxicological Endpoints and Cause Neurodegeneration in Caenorhabditis elegans

PubMed Central

Zanon, Tyler; Kappell, Anthony D.; Petrella, Lisa N.; Andersen, Erik C.; Hristova, Krassimira R.

2016-01-01

Engineered nanoparticles are becoming increasingly incorporated into technology and consumer products. In 2014, over 300 tons of copper oxide nanoparticles were manufactured in the United States. The increased production of nanoparticles raises concerns regarding the potential introduction into the environment or human exposure. Copper oxide nanoparticles commonly release copper ions into solutions, which contribute to their toxicity. We quantified the inhibitory effects of both copper oxide nanoparticles and copper sulfate on C. elegans toxicological endpoints to elucidate their biological effects. Several toxicological endpoints were analyzed in C. elegans, including nematode reproduction, feeding behavior, and average body length. We examined three wild C. elegans isolates together with the Bristol N2 laboratory strain to explore the influence of different genotypic backgrounds on the physiological response to copper challenge. All strains exhibited greater sensitivity to copper oxide nanoparticles compared to copper sulfate, as indicated by reduction of average body length and feeding behavior. Reproduction was significantly reduced only at the highest copper dose, though still more pronounced with copper oxide nanoparticles compared to copper sulfate treatment. Furthermore, we investigated the effects of copper oxide nanoparticles and copper sulfate on neurons, cells with known vulnerability to heavy metal toxicity. Degeneration of dopaminergic neurons was observed in up to 10% of the population after copper oxide nanoparticle exposure. Additionally, mutants in the divalent-metal transporters, smf-1 or smf-2, showed increased tolerance to copper exposure, implicating both transporters in copper-induced neurodegeneration. These results highlight the complex nature of CuO nanoparticle toxicity, in which a nanoparticle-specific effect was observed in some traits (average body length, feeding behavior) and a copper ion specific effect was observed for other traits (neurodegeneration, response to stress). PMID:27911941

Titanium-doped cerium oxide nanoparticles protect cells from hydrogen peroxide-induced apoptosis

PubMed Central

Clark, Andrea; Zhu, Aiping; Petty, Howard R.

2014-01-01

To develop new nanoparticle materials possessing anti-oxidative capacity with improved physical characteristics, we have studied titanium-doped cerium oxide (CeTiO2) nanoparticles. CeTiO2 nanoparticles had a mode diameter of 15-20 nm. These nanoparticles demonstrated catalase activity, and did not promote the activation of hemolytic or cytolytic pathways in living cells. Using surface plasmon resonance enhanced microscopy, we find that these nanoparticles associate with cells. Transmission electron microscopy studies demonstrated that these nanoparticles accumulate within the vacuolar compartment of cells. Importantly, CeTiO2 nanoparticles decrease hydrogen peroxide-mediated apoptosis of cells as judged by the reduced cleavage of a caspase 3-sensitive label. CeTiO2 nanoparticles may contribute to deflecting tissue damage in a broad spectrum of oxidant-mediated diseases, such as macular degeneration and Alzheimer's disease. PMID:24791147

Analysis of SiO2 nanoparticles binding proteins in rat blood and brain homogenate.

PubMed

Shim, Kyu Hwan; Hulme, John; Maeng, Eun Ho; Kim, Meyoung-Kon; An, Seong Soo A

2014-01-01

A multitude of nanoparticles, such as titanium oxide (TiO2), zinc oxide, aluminum oxide, gold oxide, silver oxide, iron oxide, and silica oxide, are found in many chemical, cosmetic, pharmaceutical, and electronic products. Recently, SiO2 nanoparticles were shown to have an inert toxicity profile and no association with an irreversible toxicological change in animal models. Hence, exposure to SiO2 nanoparticles is on the increase. SiO2 nanoparticles are routinely used in numerous materials, from strengthening filler for concrete and other construction composites, to nontoxic platforms for biomedical application, such as drug delivery and theragnostics. On the other hand, recent in vitro experiments indicated that SiO2 nanoparticles were cytotoxic. Therefore, we investigated these nanoparticles to identify potentially toxic pathways by analyzing the adsorbed protein corona on the surface of SiO2 nanoparticles in the blood and brain of the rat. Four types of SiO2 nanoparticles were chosen for investigation, and the protein corona of each type was analyzed using liquid chromatography-tandem mass spectrometry technology. In total, 115 and 48 plasma proteins from the rat were identified as being bound to negatively charged 20 nm and 100 nm SiO2 nanoparticles, respectively, and 50 and 36 proteins were found for 20 nm and 100 nm arginine-coated SiO2 nanoparticles, respectively. Higher numbers of proteins were adsorbed onto the 20 nm sized SiO2 nanoparticles than onto the 100 nm sized nanoparticles regardless of charge. When proteins were compared between the two charges, higher numbers of proteins were found for arginine-coated positively charged SiO2 nanoparticles than for the negatively charged nanoparticles. The proteins identified as bound in the corona from SiO2 nanoparticles were further analyzed with ClueGO, a Cytoscape plugin used in protein ontology and for identifying biological interaction pathways. Proteins bound on the surface of nanoparticles may affect functional and conformational properties and distributions in complicated biological processes.

Effect of Nanoparticles on Complement System in Cell Culture Model

DTIC Science & Technology

2006-09-15

case complement activation considerably differs between nanoparticles , being the highest in case of fullerene, ferric oxide and aluminium oxide ... oxide (CdO; 1 µm), manganese oxide (MnO2; 1-2 µm), and tungsten (W; 27 µm) were assessed. Additionally the effects of nanoparticles coated with...using in vitro system. Obtained results indicate that: 1. Nanoparticles toxicity in vitro can’t be measured using methods which were designed

Study of physical properties of metal oxide nanoparticles obtained in acoustoplasma discharge

NASA Astrophysics Data System (ADS)

Bulychev, N. A.; Kazaryan, M. A.; Zakharyan, A. R.; Bodryshev, V. V.; Kirichenko, M. N.; Shevchenko, S. N.; Yakunin, V. G.; Timoshenko, V. Y.; Bychenko, A. B.

2018-04-01

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.

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.

On second harmonic generation and multiphoton-absorption induced luminescence from laser-reshaped silver nanoparticles embedded in glass.

PubMed

Zolotovskaya, S A; Tyrk, M A; Stalmashonak, A; Gillespie, W A; Abdolvand, A

2016-10-28

Spherical silver nanoparticles (NPs) of 30 nm diameter embedded in soda-lime glass were uniformly reshaped (elongated) after irradiation by a linearly polarised 250 fs pulsed laser operating within the NPs' surface plasmon resonance band. We observed second harmonic generation (SHG) and multiphoton-absorption-induced luminescence (MAIL) in the embedded laser-reshaped NPs upon picosecond (10 ps) pulsed laser excitation at 1064 nm. A complementary study of SHG and MAIL was conducted in soda-lime glass containing embedded, mechanically-reshaped silver NPs of a similar elongation ratio (aspect ratio) to the laser-reshaped NPs. This supports the notion that the observed difference in SHG and MAIL in the studied nanocomposite systems is due to the shape modification mechanism. The discrete dipole approximation method was used to assess the absorption and scattering cross-sections of the reshaped NPs with different elongation ratios.

Photovoltaic Properties and Ultrafast Plasmon Relaxation Dynamics of Diamond-Like Carbon Nanocomposite Films with Embedded Ag Nanoparticles.

PubMed

Meškinis, Šarūnas; Peckus, Domantas; Vasiliauskas, Andrius; Čiegis, Arvydas; Gudaitis, Rimantas; Tamulevičius, Tomas; Yaremchuk, Iryna; Tamulevičius, Sigitas

2017-12-01

Ultrafast relaxation dynamics of diamond-like carbon (DLC) films with embedded Ag nanoparticles (DLC:Ag) and photovoltaic properties of heterojunctions consisting of DLC:Ag and crystalline silicon (DLC:Ag/Si) were investigated by means of transient absorption (TAS) spectroscopy and photovoltaic measurements. The heterojunctions using both p type and n type silicon were studied. It was found that TAS spectra of DLC:Ag films were dependent on the used excitation wavelength. At wavelengths where Ag nanoparticles absorbed light most intensively, only DLC signal was registered. This result is in good accordance with an increase of the DLC:Ag/Si heterojunction short circuit current and open circuit voltage with the excitation wavelength in the photovoltaic measurements. The dependence of the TAS spectra of DLC:Ag films and photovoltaic properties of DLC:Ag/Si heterostructures on the excitation wavelength was explained as a result of trapping of the photoexcited hot charge carriers in DLC matrix. The negative photovoltaic effect was observed for DLC:Ag/p-Si heterostructures and positive ("conventional") for DLC:Ag/n-Si ones. It was explained by the excitation of hot plasmonic holes in the Ag nanoparticles embedded into DLC matrix. Some decrease of DLC:Ag/Si heterostructures photovoltage as well as photocurrent with DLC:Ag film thickness was observed, indicating role of the interface in the charge transfer process of photocarriers excited in Ag nanoparticles.

Photovoltaic Properties and Ultrafast Plasmon Relaxation Dynamics of Diamond-Like Carbon Nanocomposite Films with Embedded Ag Nanoparticles

NASA Astrophysics Data System (ADS)

Meškinis, Šarūnas; Peckus, Domantas; Vasiliauskas, Andrius; Čiegis, Arvydas; Gudaitis, Rimantas; Tamulevičius, Tomas; Yaremchuk, Iryna; Tamulevičius, Sigitas

2017-04-01

Ultrafast relaxation dynamics of diamond-like carbon (DLC) films with embedded Ag nanoparticles (DLC:Ag) and photovoltaic properties of heterojunctions consisting of DLC:Ag and crystalline silicon (DLC:Ag/Si) were investigated by means of transient absorption (TAS) spectroscopy and photovoltaic measurements. The heterojunctions using both p type and n type silicon were studied. It was found that TAS spectra of DLC:Ag films were dependent on the used excitation wavelength. At wavelengths where Ag nanoparticles absorbed light most intensively, only DLC signal was registered. This result is in good accordance with an increase of the DLC:Ag/Si heterojunction short circuit current and open circuit voltage with the excitation wavelength in the photovoltaic measurements. The dependence of the TAS spectra of DLC:Ag films and photovoltaic properties of DLC:Ag/Si heterostructures on the excitation wavelength was explained as a result of trapping of the photoexcited hot charge carriers in DLC matrix. The negative photovoltaic effect was observed for DLC:Ag/p-Si heterostructures and positive ("conventional") for DLC:Ag/n-Si ones. It was explained by the excitation of hot plasmonic holes in the Ag nanoparticles embedded into DLC matrix. Some decrease of DLC:Ag/Si heterostructures photovoltage as well as photocurrent with DLC:Ag film thickness was observed, indicating role of the interface in the charge transfer process of photocarriers excited in Ag nanoparticles.

Magnetic Characterization of Iron Oxide Nanoparticles for Biomedical Applications.

PubMed

Maldonado-Camargo, Lorena; Unni, Mythreyi; Rinaldi, Carlos

2017-01-01

Iron oxide nanoparticles are of interest in a wide range of biomedical applications due to their response to applied magnetic fields and their unique magnetic properties. Magnetization measurements in constant and time-varying magnetic field are often carried out to quantify key properties of iron oxide nanoparticles. This chapter describes the importance of thorough magnetic characterization of iron oxide nanoparticles intended for use in biomedical applications. A basic introduction to relevant magnetic properties of iron oxide nanoparticles is given, followed by protocols and conditions used for measurement of magnetic properties, along with examples of data obtained from each measurement, and methods of data analysis.

Nanocomposites based on self-assembly poly(hydroxypropyl methacrylate)-block-poly(N-phenylmaleimide) and Fe3O4-NPs. Thermal stability, morphological characterization and optical properties

NASA Astrophysics Data System (ADS)

Pizarro, Guadalupe del C.; Marambio, Oscar G.; Jeria-Orell, Manuel; Sánchez, Julio; Oyarzún, Diego P.

2018-02-01

The current work presents the synthesis, characterization and preparation of organic-inorganic hybrid polymer films that contain inorganic magnetic nanoparticles (NPs). The block copolymer, prepared by Atom-Transfer Radical Polymerization (ATRP), was used as a nanoreactor for iron oxide NPs. The NPs were embedded in poly(hydroxypropyl methacrylate)-block-poly(N-phenylmaleimide) matrix. The following topographical modifications of the surface of the film were specially analyzed: control of pore features and changes in surface roughness. Finally, the NPs functionality inside the polymer matrix and how it may affect the thermal and optical properties of the films were assessed.

Investigation of sacrificial layer and building block for layered nanofabrication (LNF)

NASA Astrophysics Data System (ADS)

Shih, Ting-Yu

Layered Nanoscale Fabrication (LNF) is a "bottom-up" procedure that uses multiple layers to build 3-dimensional nanoscale structures. Here, in this dissertation, several candidates for sacrificial layers were explored, The thermal stability of gold nanoparticles and simple patterns are also reported. In order to obtain information on layer thickness and film quality; the samples were characterized using atomic force microscopy (AFM) and ellipsometry. Octadecyltrichlorosilane (OTS) was first investigated for use as a sacrificial layer and we studied filth growth by targeted self-replication of silane multilayers with and without the presence of thiolated gold nanoparticles on silicon oxide substrates. The particles adhered to the substrate during layer grafting. The film grew selectively on the substrate, without covering the particles. AFM was used to investigate the growth mechanism and the process of embedding the nanoparticles. OTS multilayer films up to 9 layers were grown in a linear, bilayer-by bilayer mode, free of islands and defects. We also report on studies of monolayer and multilayer formation of Methyl-11-dimethylmonochlorosilyl-undecanoate films. Flat multilayers up to 3-layers thick were grown. AFM was used to measure the height of an observable "edge" of the multilayer film and this provides and independent determination of the MOSUD layer height of 1.5 nm: However, the particles detached from the surface when we attempted to grow multilayer. One strategy of linking the particles to form 2D arrays, thermal activation in ambient air, was investigated. The morphological properties of flaked nanoparticles and structures on silicon oxide substrates before and after heating were characterized by using AFM. For widely separated 5 nm gold nanoparticles height decreased over 50% at 600 °C. Further heating to 630 °C caused most particles to completely disappear, with small amount of particle residue left on the surface. Particles positioned near to other particles first formed a neck-like structure at 570 °C and then deformed into one wide particle with tail-shape residue at 650 °C. Clusters of Au nanoparticles rearranged and became one large collide with particles residues left on the surface at 630 °C.

Preparation and characterization of iron oxide magnetic nanoparticles functionalized by nisin.

PubMed

Gruskiene, Ruta; Krivorotova, Tatjana; Staneviciene, Ramune; Ratautas, Dalius; Serviene, Elena; Sereikaite, Jolanta

2018-05-08

Nisin is a known bacteriocin approved as a food additive for food preservation. It exhibits a wide spectrum antimicrobial activity against Gram-positive bacteria. Iron oxide magnetic nanoparticles were synthesized and characterized by X-ray diffraction method. A main part of iron oxide nanoparticles was found to be maghemite though a small quantity of magnetite could also be present. Magnetic nanoparticles were stabilized by citric, ascorbic, gallic or glucuronic acid coating. Stable iron oxide magnetic nanoparticles were functionalized by nisin using a simple and low cost adsorption method. Nisin loading was confirmed by FT-IR spectra, thermogravimetric analysis, dynamic light scattering and atomic force microscopy methods. Nisin-loaded iron oxide magnetic nanoparticles were stable at least six weeks as judged by the measurements of zeta-potential and hydrodynamic diameter. The antimicrobial activity of nisin-loaded iron oxide magnetic nanoparticles was demonstrated toward Gram-positive bacteria. Functionalized nanoparticles could therefore find the application as antimicrobials in innovative and emerging technologies based on the magnetic field. Copyright © 2018 Elsevier B.V. All rights reserved.

An image processing approach for investigation on transport of iron oxide nanoparticles (FE3O4) stabilized with poly acrylic acid in two-dimensional porous media

NASA Astrophysics Data System (ADS)

Golzar, M.; Azhdary Moghaddam, M.; Saghravani, S. F.; Dahrazma, B.

2018-04-01

Iron oxide nanoparticles were stabilized using poly acrylic acid (PAA) to yield stabilized slurry of Iron oxide nanoparticles. A two-dimensional physical model filled by glass beads was used to study the fate and transport of the iron oxide nanoparticles stabilized with PAA in porous media under saturated, steady-state flow conditions. Transport data for a nonreactive tracer, slurry of iron oxide nanoparticles stabilized with PAA were collected under similar flow conditions. The results show that low concentration slurry of iron oxide nanoparticles stabilized with PAA can be transported like a tracer without significant retardation. The image processing technique was employed to measure the tracer/nanoparticle concentration inside the 2-D model filled with glass beads. The groundwater flow model, Visual MODFLOW, was used to model the observed transport patterns through MT3DMS module. Finally, it was demonstrated that the numerical model MODFLOW can be used to predict the fate and transport characteristics of nanoparticles stabilized with PAA in groundwater aquifers.

Assessment of the cytotoxicity of aluminium oxide nanoparticles on selected mammalian cells.

PubMed

Radziun, E; Dudkiewicz Wilczyńska, J; Książek, I; Nowak, K; Anuszewska, E L; Kunicki, A; Olszyna, A; Ząbkowski, T

2011-12-01

The rapid development of nanotechnology raises both enthusiasm and anxiety among researchers, which is related to the safety use of the manufactured materials. Thus, the aim of this study was to investigate the effect of aluminium oxide nanoparticles on the viability of selected mammalian cells in vitro. The aluminium oxide nanoparticles were characterised using SEM and BET analyses. Based on Zeta (ζ) potential measurements and particle size distribution, the tested suspensions of aluminium oxide nanoparticles in water and nutrient solutions with or without FBS were classified as unstable. Cell viability, the degree of apoptosis induction and nanoparticles internalization into the cells were assessed after 24 h of cell exposure to Al2O3 nanoparticles. Our results confirm the ability of aluminium oxide nanoparticles to penetrate through the membranes of L929 and BJ cells. Despite this, there was no significant increase in apoptosis or decrease in cell viability observed, suggesting that aluminium oxide nanoparticles in the tested range of concentrations has no cytotoxic effects on the selected mammalian cells. Copyright © 2011 Elsevier Ltd. All rights reserved.

Application of nanodimensional particles and aluminum hydroxide nanostructures for cancer diagnosis and therapy

NASA Astrophysics Data System (ADS)

Korovin, M. S.; Fomenko, A. N.

2017-09-01

Nanoparticles and nanostructured materials are one of the most promising developments for cancer therapy. Gold nanoparticles, magnetic nanoparticles based on iron and its oxides and other metal oxides have been widely used in diagnosis and treatment of cancer. Much less researchers' attention has been paid to nanoparticles and nanostructures based on aluminum oxides and hydroxides as materials for cancer diagnosis and treatment. However, recent investigations have shown promising results regarding these objects. Here, we review the antitumor results obtained with different aluminum oxide/hydroxide nanoparticles and nanostructures.

Human nitric oxide biomarker as potential NO donor in conjunction with superparamagnetic iron oxide @ gold core shell nanoparticles for cancer therapeutics.

PubMed

Singh, Nimisha; Patel, Khushbu; Sahoo, Suban K; Kumar, Rajender

2018-03-01

Nitric oxide releasing superparamagnetic (Fe 3 O 4 -Au@NTHP) nanoparticles were synthesized by conjugation of human biomarker of nitric oxide, N-nitrosothioproline with iron oxide-gold (Fe 3 O 4 -Au) core shell nanoparticles. The structure and morphology of the prepared nanoparticles were confirmed by ATR-FTIR, HR-TEM, EDAX, XPS, DLS and VSM measurements. N-nitrosothioproline is a natural molecule and nontoxic to humans. Thus, the core shell nanoparticles prepared were highly biocompatible. The prepared Fe 3 O 4 -Au@NTHP nanoparticles also provided an excellent release of nitric oxide in dark and upon light irradiation for cancer treatment. The amount of NO release was controllable with the wavelength of light and time of irradiation. The developed nanoparticles provided efficient cellular uptake and good cytotoxicity in picomolar range when tested on HeLa cancerous cells. These nanoparticles on account of their controllable NO release can also be used to release small amount of NO for killing cancerous cells without any toxic effect. Furthermore, the magnetic and photochemical properties of these nanoparticles provides dual platform for magneto therapy and phototherapy for cancer treatment. Copyright © 2017 Elsevier B.V. All rights reserved.

Volume-labeled nanoparticles and methods of preparation

DOEpatents

Wang, Wei; Gu, Baohua; Retterer, Scott T; Doktycz, Mitchel J

2015-04-21

Compositions comprising nanosized objects (i.e., nanoparticles) in which at least one observable marker, such as a radioisotope or fluorophore, is incorporated within the nanosized object. The nanosized objects include, for example, metal or semi-metal oxide (e.g., silica), quantum dot, noble metal, magnetic metal oxide, organic polymer, metal salt, and core-shell nanoparticles, wherein the label is incorporated within the nanoparticle or selectively in a metal oxide shell of a core-shell nanoparticle. Methods of preparing the volume-labeled nanoparticles are also described.

Multifunctional superparamagnetic nanoparticles for enhanced drug transport in cystic fibrosis

NASA Astrophysics Data System (ADS)

Armijo, Leisha M.; Brandt, Yekaterina I.; Rivera, Antonio C.; Cook, Nathaniel C.; Plumley, John B.; Withers, Nathan J.; Kopciuch, Michael; Smolyakov, Gennady A.; Huber, Dale L.; Smyth, Hugh D.; Osinski, Marek

2012-10-01

Iron oxide colloidal nanoparticles (ferrofluids) are investigated for application in the treatment of cystic fibrosis lung infections, the leading cause of mortality in cystic fibrosis patients. We investigate the use of iron oxide nanoparticles to increase the effectiveness of administering antibiotics through aerosol inhalation using two mechanisms: directed particle movement in the presence of an inhomogeneous static external magnetic field and magnetic hyperthermia. Magnetic hyperthermia is an effective method for decreasing the viscosity of the mucus and biofilm, thereby enhancing drug, immune cell, and antibody penetration to the affected area. Iron oxide nanoparticles of various sizes and morphologies were synthesized and tested for specific losses (heating power). Nanoparticles in the superparamagnetic to ferromagnetic size range exhibited excellent heating power. Additionally, iron oxide / zinc selenide core/shell nanoparticles were prepared, in order to enable imaging of the iron oxide nanoparticles. We also report on synthesis and characterization of MnSe/ZnSeS alloyed quantum dots.

A review of the irradiation evolution of dispersed oxide nanoparticles in the b.c.c. Fe-Cr system: Current understanding and future directions

NASA Astrophysics Data System (ADS)

Wharry, Janelle P.; Swenson, Matthew J.; Yano, Kayla H.

2017-04-01

Thus far, a number of studies have investigated the irradiation evolution of oxide nanoparticles in b.c.c. Fe-Cr based oxide dispersion strengthened (ODS) alloys. But given the inconsistent experimental conditions, results have been widely variable and inconclusive. Crystal structure and chemistry changes differ from experiment to experiment, and the total nanoparticle volume fraction has been observed to both increase and decrease. Furthermore, there has not yet been a comprehensive review of the archival literature. In this paper, we summarize the existing studies on nanoparticle irradiation evolution. We note significant observations with respect to oxide nanoparticle crystallinity, composition, size, and number density. We discuss four possible contributing mechanisms for nanoparticle evolution: ballistic dissolution, Ostwald ripening, irradiation-enhanced diffusion, and homogeneous nucleation. Finally, we propose future directions to achieve a more comprehensive understanding of irradiation effects on oxide nanoparticles in ODS alloys.

Electrosprayed Cerium Oxide Nanoparticles

NASA Astrophysics Data System (ADS)

Azar, Pedram Bagherzadeh; Tavanai, Hossein; Allafchian, Ali Reza

2018-04-01

Cerium oxide nanoparticles were fabricated via the calcination of electrosprayed polyvinyl alcohol (PVA)/cerium nitrate nanoparticles. The effect of material variables of PVA/cerium nitrate electrospraying solution, i.e. viscosity, surface tension and electrical conductivity, as well as important process variables like voltage, nozzle-collector distance and feed rate on cerium oxide nanoparticle size, are investigated. Scanning electron microscopy and Fourier-transform infrared (FTIR) spectroscopy analysis have also been carried out. The results showed that electrospraying of PVA/cerium nitrate (25% w/v) was only possible with PVA concentrations in the range of 5-8% w/v. With other conditions constant, decreasing PVA concentration, decreasing feed rate, increasing nozzle-collector distance and increasing voltage decreased the size of the final cerium oxide nanoparticles. The gross average size of all cerium oxide nanoparticles obtained in this work was about 80 nm. FTIR analysis proved the formation of cerium oxide after the calcination process.

Green synthesis of colloidal copper oxide nanoparticles using Carica papaya and its application in photocatalytic dye degradation

NASA Astrophysics Data System (ADS)

Sankar, Renu; Manikandan, Perumal; Malarvizhi, Viswanathan; Fathima, Tajudeennasrin; Shivashangari, Kanchi Subramanian; Ravikumar, Vilwanathan

2014-03-01

Copper oxide (CuO) nanoparticles were synthesized by treating 5 mM cupric sulphate with Carica papaya leaves extract. The kinetics of the reaction was studied using UV-visible spectrophotometry. An intense surface Plasmon resonance between 250-300 nm in the UV-vis spectrum clearly reveals the formation of copper oxide nanoparticles. The results of scanning electron microscopy (SEM) and dynamic light scattering (DLS) exhibited that the green synthesized copper oxide nanoparticles are rod in shape and having a mean particle size of 140 nm, further negative zeta potential disclose its stability at -28.9 mV. The Fourier-transform infrared (FTIR) spectroscopy results examined the occurrence of bioactive functional groups required for the reduction of copper ions. X-ray diffraction (XRD) spectra confirmed the copper oxide nanoparticles crystalline nature. Furthermore, colloidal copper oxide nanoparticles effectively degrade the Coomassie brilliant blue R-250 dye beneath the sunlight.

Anomalous thermal hysteresis in the high-field magnetic moments of magnetic nanoparticles embedded in multi-walled carbon nanotubes

NASA Astrophysics Data System (ADS)

Zhao, Guo-Meng; Wang, Jun; Ren, Yang; Beeli, Pieder

2012-02-01

We report high-temperature (300-1120 K) magnetic properties of Fe and Fe3O4 nanoparticles embedded in multi-walled carbon nanotubes. We unambiguously show that the magnetic moments of Fe and Fe3O4 nanoparticles are seemingly enhanced by a factor of about 3 compared with what they would be expected to have for free (unembedded) magnetic nanoparticles. What is more intriguing is that the enhanced moments were completely lost when the sample was heated up to 1120 K and the lost moments at 1120 K were completely recovered through several thermal cycles below 1020 K. The anomalous thermal hysteresis of the high-field magnetic moments is unlikely to be explained by existing physical models except for the high-field paramagnetic Meissner effect due to the existence of ultrahigh temperature superconductivity in the multi-walled carbon nanotubes.

Green synthesis and characterization of zinc oxide nanoparticle using insulin plant (Costus pictus D. Don) and investigation of its antimicrobial as well as anticancer activities

NASA Astrophysics Data System (ADS)

Suresh, Joghee; Pradheesh, Ganeshan; Alexramani, Vincent; Sundrarajan, Mahalingam; Hong, Sun Ig

2018-03-01

In this work we aim to synthesize biocompatible ZnO nanoparticles from the zinc nitrate via green process using leaf extracts of the Costus pictus D. Don medicinal plant. FTIR studies confirm the presence of biomolecules and metal oxides. X-ray diffraction (XRD) structural analysis reveals the formation of pure hexagonal phase structures of ZnO nanoparticles. The surface morphologies of ZnO nanoparticles observed under a scanning electron microscope (SEM) suggest that most ZnO crystallites are hexagonal. EDX analysis confirms the presence of primarily zinc and oxygen. TEM images show that biosynthesized zinc oxide nanoparticles are hexagonal and spherical. The plausible formation mechanisms of zinc oxide nanoparticles are also predicted. The biosynthesized zinc oxide nanoparticles exhibit strong antimicrobial behavior against bacterial and fungal species when employing the agar diffusion method. Synthesized ZnO nanoparticles exhibit anticancer activity against Daltons lymphoma ascites (DLA) cells as well as antimicrobial activity against some bacterial and fungal strains.

Biosynthesis of cobalt oxide nanoparticles using endophytic fungus Aspergillus nidulans.

PubMed

Vijayanandan, Ajuy Sundar; Balakrishnan, Raj Mohan

2018-07-15

Metallic oxide nanoparticles have profound applications in electrochemical devices, supercapacitors, biosensors and batteries. Though four fungi were isolated from Nothapodytes foetida, Aspergillus nidulans was found to be suitable for synthesis of cobalt oxide nanoparticles, as it has proficient tolerance towards metal under study. The broth containing precursor solution and organism Aspergillus nidulans had changed from pink to orange indicating the formation of nanoparticles. Characterization by x-ray diffraction analysis (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and energy dispersive x-ray analysis (EDX) confirmed the formation of spinel cobalt oxide nanoparticles at an average size of 20.29 nm in spherical shape with sulfur-bearing proteins acting as a capping agent for the synthesized nanoparticles. The nanoparticles could be applied in energy storage, as a specific capacitance of 389 F/g showed competence. The study was a greener attempt to synthesize cobalt oxide nanoparticles using endophytic fungus. Copyright © 2018 Elsevier Ltd. All rights reserved.

Biosynthesis and characterization of Acalypha indica mediated copper oxide nanoparticles and evaluation of its antimicrobial and anticancer activity.

PubMed

Sivaraj, Rajeshwari; Rahman, Pattanathu K S M; Rajiv, P; Narendhran, S; Venckatesh, R

2014-08-14

Copper oxide nanoparticles were synthesized by biological method using aqueous extract of Acalypha indica leaf and characterized by UV-visible spectroscopy, XRD, FT-IR, SEM TEM and EDX analysis. The synthesised particles were highly stable, spherical and particle size was in the range of 26-30 nm. The antimicrobial activity of A.indica mediated copper oxide nanoparticles was tested against selected pathogens. Copper oxide nanoparticles showed efficient antibacterial and antifungal effect against Escherichia coli, Pseudomonas fluorescens and Candida albicans. The cytotoxicity activity of A.indica mediated copper nanoparticles was evaluated by MTT assay against MCF-7 breast cancer cell lines and confirmed that copper oxide nanoparticles have cytotoxicity activity. Copyright © 2014 Elsevier B.V. All rights reserved.

Conductivity and structure of ErAs nanoparticles embedded in GaAs pn junctions analyzed via conductive atomic force microscopy

NASA Astrophysics Data System (ADS)

Park, K. W.; Dasika, V. D.; Nair, H. P.; Crook, A. M.; Bank, S. R.; Yu, E. T.

2012-06-01

We have used conductive atomic force microscopy to investigate the influence of growth temperature on local current flow in GaAs pn junctions with embedded ErAs nanoparticles grown by molecular beam epitaxy. Three sets of samples, one with 1 ML ErAs deposited at different growth temperatures and two grown at 530 °C and 575 °C with varying ErAs depositions, were characterized. Statistical analysis of local current images suggests that the structures grown at 575 °C have about 3 times thicker ErAs nanoparticles than structures grown at 530 °C, resulting in degradation of conductivity due to reduced ErAs coverage. These findings explain previous studies of macroscopic tunnel junctions.

Nitrogen-doped mesoporous carbon-armored cobalt nanoparticles as efficient hydrogen evolving electrocatalysts.

PubMed

Tang, Duihai; Li, Kuo; Zhang, Wenting; Qiao, Zhen-An; Zhu, Junjiang; Zhao, Zhen

2018-03-15

A series of Co nanoparticles embedded, N-doped mesoporous carbons have been synthesized through chelate-assisted co-assembly strategy followed by thermal treatment. The preparation is based on an assembly process, with evaporation of an ethanol-water solution containing melamine formaldehyde resin (MF resin) as carbon source, nitrogen source, and chelating agent. Moreover, F127 and Co(NO 3 ) 2 are used as template and metallic precursor, respectively. The Co nanoparticles embedded, N-doped mesoporous carbon annealed at 800 °C (denoted as MFCo800) shows high electrocatalytic activity for hydrogen evolution reaction (HER) with high current density and low overpotential, which has the ability to operate in both acidic and alkaline electrolytes. Copyright © 2017. Published by Elsevier Inc.

Environment friendly route of iron oxide nanoparticles from Zingiber officinale (ginger) root extract

NASA Astrophysics Data System (ADS)

Xin Hui, Yau; Yi Peng, Teoh; Wei Wen, Liu; Zhong Xian, Ooi; Peck Loo, Kiew

2016-11-01

Iron oxide nanoparticles were prepared from the reaction between the Zingiber officinale (ginger) root extracts and ferric chloride solution at 50°C for 2 h in mild stirring condition. The synthesized powder forms of nanoparticles were further characterized by using UV-Vis spectroscopy and X-ray Diffraction spectrometry. UV-Vis analysis shows the absorption peak of iron oxide nanoparticles is appeared at 370 nm. The calculation of crystallite size from the XRD showed that the average particle size of iron oxide nanoparticles was 68.43 nm. Therefore, this eco-friendly technique is low cost and large scale nanoparticles synthesis to fulfill the demand of various applications.

Impact of nanoparticles and butanol on properties and spray characteristics of waste cooking oil biodiesel and pure rapeseed oil

NASA Astrophysics Data System (ADS)

Ahmad, K. H.; Hossain, A. K.

2017-11-01

Renewable biofuels can offset greenhouse gases by replacing fossil fuels destined for internal combustion engines. However, biofuels have their own setbacks and may lead to poor combustion inside the engine cylinder. In this study, nanoparticles and butanol were blended either separately or together with waste cooking oil biodiesel and neat rape seed oil to investigate the impact of these additives on the properties and spray characteristics. The investigation comprised of three stages, with each having an effect on how the next stage of the investigation was conducted. Initially, the physicochemical characteristics of 25ppm, 50ppm, 75ppm and 100ppm concentrations of aluminium oxide and copper oxide nanoparticle blends with fossil diesel, waste cooking oil biodiesel and rapeseed oil were investigated. The results from first stage investigation showed that, in general, blends containing aluminium oxide nanoparticles gave better results for almost all the concentrations when compared with copper oxide nanoparticle blends with the same nanoparticle concentrations. Overall, waste cooking oil biodiesel blended with 100ppm aluminium oxide nanoparticle showed most promising results like the flash point of 159.3°C, kinematic viscosity @40°C of 4.66 cSt, and gross calorific value of 44.43 MJ/kg. These values were 61.6% higher, 51.3% higher and 3.2% lower than that of corresponding fossil diesel values. Subsequently, in the second stage of the study, the addition of butanol was investigated to assess its ability to enhance the emulsion of biofuel-nanoparticles blends. Four blends containing 90% biodiesel & 10% butanol, and 90% rapeseed oil & 10% butanol, with and without 100ppm Al2O3 were prepared. Results showed that the kinematic viscosity of the fuel blends containing 100ppm aluminium oxide nanoparticles were decreased by 0.4% and 3.3%, for 90% biodiesel & 10% butanol and 90% rapeseed oil & 10% butanol blends respectively, when compared to without the nanoparticles. The results obtained from the second stage of investigation proved that butanol acted as a surfactant and thus addition of butanol helped to improve the properties of the biofuel-nanoparticle blends. In the third stage of the study, the spray characteristics of fossil diesel, biodiesel, biodiesel + 100ppm aluminium oxide nanoparticles, rapeseed oil, rapeseed oil + 100ppm aluminium oxide nanoparticles, 90% biodiesel & 10% butanol, 90% biodiesel & 10% butanol + 100ppm aluminium oxide nanoparticles, 90% rapeseed oil & 10% butanol and 90% rapeseed oil & 10% butanol + 100ppm aluminium oxide nanoparticles were investigated. It was found that amongst all fuels, blend containing 90% biodiesel + 10% butanol + 100ppm aluminium oxide nanoparticles gave better spray characteristics; for example, the liquid sheet angle was 7.14% lower and the spray cone angle was 7.87% higher than the corresponding fossil diesel values. The study concluded that the spray characteristics and properties of biofuels could be improved by blending with both aluminium oxide nanoparticles and butanol.

Effects of sub-acute exposure to TiO2, ZnO and Al2O3 nanoparticles on oxidative stress and histological changes in mouse liver and brain.

PubMed

Shrivastava, Rupal; Raza, Saimah; Yadav, Abhishek; Kushwaha, Pramod; Flora, Swaran J S

2014-07-01

Nanomaterials are at the leading edge of the rapidly developing field of nanotechnology. However the information regarding toxicity of these nanoparticles on humans and environment is still deficient. The present study investigated the toxic effects of three metal oxide nanoparticles, TiO2, ZnO and Al2O3 on mouse erythrocytes, brain and liver. Male mice were administered a single oral dose of 500 mg/kg of each nanoparticles for 21 consecutive days. The results suggest that exposure to these nano metallic particles produced a significant oxidative stress in erythrocyte, liver and brain as evident from enhanced levels of Reactive Oxygen Species (ROS) and altered antioxidant enzymes activities. A significant increase in dopamine and norepinephrine levels in brain cerebral cortex and increased brain oxidative stress suggest neurotoxic potential of these nanoparticles. Transmission electron microscopic (TEM) analysis indicated the presence of these nanoparticles inside the cytoplasm and nucleus. These changes were also supported by the inhibition of CuZnSOD and MnSOD, considered as important biomarkers of oxidative stress. The toxic effects produced by these nanoparticles were more pronounced in the case of zinc oxide, followed by aluminum oxide and titanium dioxide, respectively. The present results further suggest the involvement of oxidative stress as one of the main mechanisms involved in nanoparticles induced toxic manifestations.

Pulsed laser ablation synthesis of silver nanoparticles and their use in fluorescence enhancement of Tb3+-doped aluminosilicate glass

NASA Astrophysics Data System (ADS)

Verma, R. K.; Kumar, K.; Rai, S. B.

2010-10-01

Spherical silver nanoparticles have been synthesized using laser ablation in distilled water. These nanoparticles are embedded in Tb 3+-doped aluminosilicate glass through the sol-gel technique. The presence of these nanoparticles is seen to increase the emission intensity of the Tb 3+ ions by more than 100%. Energy transfer from the excited silver nanoparticles to Tb 3+ ions is the probable cause for this increase in emission intensity.

Fabrication of oxidation-resistant Ge colloidal nanoparticles by pulsed laser ablation in aqueous HCl

NASA Astrophysics Data System (ADS)

Hamanaka, Yasushi; Iwata, Masahiro; Katsuno, Junichi

2017-06-01

Spherical Ge nanoparticles with diameters of 20-80 nm were fabricated by laser ablation of a Ge single crystal in water and in aqueous HCl using sub-picosecond laser pulses (1040 nm, 700 fs, 100 kHz, and a pulse energy of 10 µJ). We found that the as-synthesized nanoparticles suffered rapid oxidization followed by dissolution when laser ablation was conducted in pure water. In contrast, oxidation of Ge nanoparticles produced in dilute HCl and stored intact was minimal, and colloidal dispersions of the Ge nanoparticles remained stable up to 7 days. It was elucidated that dangling bonds on the surfaces of the Ge nanoparticles were terminated by Cl, which inhibited oxidation, and that such hydrophilic surfaces might improve the dispersibility of nanoparticles in aqueous solvent.

Identification of a Catalytically Highly Active Surface Phase for CO Oxidation over PtRh Nanoparticles under Operando Reaction Conditions

NASA Astrophysics Data System (ADS)

Hejral, U.; Franz, D.; Volkov, S.; Francoual, S.; Strempfer, J.; Stierle, A.

2018-03-01

Pt-Rh alloy nanoparticles on oxide supports are widely employed in heterogeneous catalysis with applications ranging from automotive exhaust control to energy conversion. To improve catalyst performance, an atomic-scale correlation of the nanoparticle surface structure with its catalytic activity under industrially relevant operando conditions is essential. Here, we present x-ray diffraction data sensitive to the nanoparticle surface structure combined with in situ mass spectrometry during near ambient pressure CO oxidation. We identify the formation of ultrathin surface oxides by detecting x-ray diffraction signals from particular nanoparticle facets and correlate their evolution with the sample's enhanced catalytic activity. Our approach opens the door for an in-depth characterization of well-defined, oxide-supported nanoparticle based catalysts under operando conditions with unprecedented atomic-scale resolution.

Nanoparticles as potential clinical therapeutic agents in Alzheimer's disease: focus on selenium nanoparticles.

PubMed

Nazıroğlu, Mustafa; Muhamad, Salina; Pecze, Laszlo

2017-07-01

In etiology of Alzheimer's disease (AD), involvement of amyloid β (Aβ) plaque accumulation and oxidative stress in the brain have important roles. Several nanoparticles such as titanium dioxide, silica dioxide, silver and zinc oxide have been experimentally using for treatment of neurological disease. In the last decade, there has been a great interest on combination of antioxidant bioactive compounds such as selenium (Se) and flavonoids with the oxidant nanoparticles in AD. We evaluated the most current data available on the physiological effects of oxidant and antioxidant nanoparticles. Areas covered: Oxidative nanoparticles decreased the activities of reactive oxygen species (ROS) scavenging enzymes such as glutathione peroxidase (GSH-Px), superoxide dismutase (SOD) and catalase in the brain of rats and mice. However, Se-rich nanoparticles in small size (5-15 nm) depleted Aβ formation through decreasing ROS production. Reports on low levels of Se in blood and tissue samples and the low activities of GSH-Px, catalase and SOD enzymes in AD patients and animal models support the proposed crucial role of oxidative stress in the pathogenesis of AD. Expert commentary: In conclusion, present literature suggests that Se-rich nanoparticles appeared to be a potential therapeutic compound for the treatment of AD.

DNA-length-dependent quenching of fluorescently labeled iron oxide nanoparticles with gold, graphene oxide and MoS2 nanostructures.

PubMed

Balcioglu, Mustafa; Rana, Muhit; Robertson, Neil; Yigit, Mehmet V

2014-08-13

We controlled the fluorescence emission of a fluorescently labeled iron oxide nanoparticle using three different nanomaterials with ultraefficient quenching capabilities. The control over the fluorescence emission was investigated via spacing introduced by the surface-functionalized single-stranded DNA molecules. DNA molecules were conjugated on different templates, either on the surface of the fluorescently labeled iron oxide nanoparticles or gold and nanographene oxide. The efficiency of the quenching was determined and compared with various fluorescently labeled iron oxide nanoparticle and nanoquencher combinations using DNA molecules with three different lengths. We have found that the template for DNA conjugation plays significant role on quenching the fluorescence emission of the fluorescently labeled iron oxide nanoparticles. We have observed that the size of the DNA controls the quenching efficiency when conjugated only on the fluorescently labeled iron oxide nanoparticles by setting a spacer between the surfaces and resulting change in the hydrodynamic size. The quenching efficiency with 12mer, 23mer and 36mer oligonucleotides decreased to 56%, 54% and 53% with gold nanoparticles, 58%, 38% and 32% with nanographene oxide, 46%, 38% and 35% with MoS2, respectively. On the other hand, the presence, not the size, of the DNA molecules on the other surfaces quenched the fluorescence significantly with different degrees. To understand the effect of the mobility of the DNA molecules on the nanoparticle surface, DNA molecules were attached to the surface with two different approaches. Covalently immobilized oligonucleotides decreased the quenching efficiency of nanographene oxide and gold nanoparticles to ∼22% and ∼21%, respectively, whereas noncovalently adsorbed oligonucleotides decreased it to ∼25% and ∼55%, respectively. As a result, we have found that each nanoquencher has a powerful quenching capability against a fluorescent nanoparticle, which can be tuned with surface functionalized DNA molecules.

Toxicological Assessment of CoO and La2O3 Metal Oxide Nanoparticles in Human Small Airway Epithelial Cells

PubMed Central

Pirela, Sandra V.; Shaffer, Justine; Mihalchik, Amy L.; Chisholm, William P.; Andrew, Michael E.; Schwegler-Berry, Diane; Castranova, Vincent; Demokritou, Philip; Qian, Yong

2016-01-01

Cobalt monoxide (CoO) and lanthanum oxide (La2O3) nanoparticles are 2 metal oxide nanoparticles with different redox potentials according to their semiconductor properties. By utilizing these two nanoparticles, this study sought to determine how metal oxide nanoparticle’s mode of toxicological action is related to their physio-chemical properties in human small airway epithelial cells (SAEC). We investigated cellular toxicity, production of superoxide radicals and alterations in gene expression related to oxidative stress, and cellular death at 6 and 24 h following exposure to CoO and La2O3 (administered doses: 0, 5, 25, and 50 µg/ml) nanoparticles. CoO nanoparticles induced gene expression related to oxidative stress at 6 h. After characterizing the nanoparticles, transmission electron microscope analysis showed SAEC engulfed CoO and La2O3 nanoparticles. CoO nanoparticles were toxic after 6 and 24 h of exposure to 25.0 and 50.0 µg/ml administered doses, whereas, La2O3 nanoparticles were toxic only after 24 h using the same administered doses. Based upon the Volumetric Centrifugation Method in vivo Sedimentation, Diffusion, and Dosimetry, the dose of CoO and La2O3 nanoparticles delivered at 6 and 24 h were determined to be: CoO: 1.25, 6.25, and 12.5 µg/ml; La2O3: 5, 25, and 50 µg/ml and CoO: 4, 20, and 40 µg/ml; and La2O3: 5, 25, 50 µg/ml, respectively. CoO nanoparticles produced more superoxide radicals and caused greater stimulation of total tyrosine and threonine phosphorylation at both 6 and 24 h when compared with La2O3 nanoparticles. Taken together, these data provide evidence that different toxicological modes of action were involved in CoO and La2O3 metal oxide nanoparticle-induced cellular toxicity. PMID:26769336

Induction of oxidative stress, DNA damage, and apoptosis in a malignant human skin melanoma cell line after exposure to zinc oxide nanoparticles

PubMed Central

Alarifi, Saud; Ali, Daoud; Alkahtani, Saad; Verma, Ankit; Ahamed, Maqusood; Ahmed, Mukhtar; Alhadlaq, Hisham A

2013-01-01

The widespread use of zinc oxide (ZnO) nanoparticles worldwide exposes humans to their adverse effects, so it is important to understand their biological effects and any associated risks. This study was designed to investigate the cytotoxicity, oxidative stress, and apoptosis caused by ZnO nanoparticles in human skin melanoma (A375) cells. MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide] and lactate dehydrogenase-based cell viability assays showed a significant decrease in cell viability after exposure to ZnO nanoparticles, and phase contrast images revealed that cells treated with these nanoparticles had a lower density and a rounded morphology. ZnO nanoparticles were also found to induce oxidative stress, evidenced by generation of reactive oxygen species and depletion of the antioxidant, glutathione. Induction of apoptosis was confirmed by chromosomal condensation assay and caspase-3 activation. Further, more DNA damage was observed in cells exposed to the highest concentration of ZnO nanoparticles. These results demonstrate that ZnO nanoparticles have genotoxic potential in A375 cells, which may be mediated via oxidative stress. Our short-term exposure study showing induction of a genotoxic and apoptotic response to ZnO nanoparticles needs further investigation to determine whether there may be consequences of long-term exposure to ZnO nanoparticles. PMID:23493450

Sol–gel synthesis of SnO{sub 2}–MgO nanoparticles and their photocatalytic activity towards methylene blue degradation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bayal, Nisha; Jeevanandam, P., E-mail: jeevafcy@iitr.ernet.in

2013-10-15

Graphical abstract: - Highlights: • A simple sol–gel method for the synthesis of SnO{sub 2}–MgO nanoparticles is reported. • Band gap of SnO{sub 2} can be tuned by varying the magnesium content in SnO{sub 2}–MgO. • SnO{sub 2}–MgO shows good photocatalytic activity towards degradation of methylene blue. - Abstract: SnO{sub 2}–MgO mixed metal oxide nanoparticles were prepared by a simple sol–gel method. The nanoparticles were characterized by power X-ray diffraction, scanning electron microscopy coupled with energy dispersive X-ray analysis, transmission electron microscopy and UV–vis diffuse reflectance spectroscopy. The XRD results indicate the formation of mixed metal oxide nanoparticles and alsomore » a decrease of SnO{sub 2} crystallite size in the mixed metal oxide nanoparticles with increasing magnesium oxide content. The reflectance spectroscopy results show a blue shift of the band gap of SnO{sub 2} in the mixed metal oxide nanoparticles. The photocatalytic activity of the SnO{sub 2}–MgO nanoparticles was tested using the photodegradation of aqueous methylene blue in the presence of sunlight. The results indicate that the mixed metal oxide nanoparticles possess higher efficiency for the photodegradation of methylene blue compared to pure SnO{sub 2} nanoparticles.« less

Multifunctional gold coated iron oxide core-shell nanoparticles stabilized using thiolated sodium alginate for biomedical applications.

PubMed

Sood, Ankur; Arora, Varun; Shah, Jyoti; Kotnala, R K; Jain, Tapan K

2017-11-01

In this paper we report synthesis of aqueous based gold coated iron oxide nanoparticles to integrate the localized surface plasma resonance (SPR) properties of gold and magnetic properties of iron oxide in a single system. Iron oxide-gold core shell nanoparticles were stabilized by attachment of thiolated sodium alginate to the surface of nanoparticles. Transmission electron microscope (TEM) micrograph presents an average elementary particle size of 8.1±2.1nm. High resolution TEM (HR-TEM) and X-ray photon spectroscopy further confirms the presence of gold shell around iron oxide core. Gold coating is responsible for reducing saturation magnetization (M s ) value from ~41emu/g to ~24emu/g - in thiolated sodium alginate stabilized gold coated iron oxide core-shell nanoparticles. The drug (curcumin) loading efficiency for the prepared nanocomposites was estimated to be around 7.2wt% (72μgdrug/mg nanoparticles) with encapsulation efficiency of 72.8%. Gold-coated iron oxide core-shell nanoparticles could be of immense importance in the field of targeted drug delivery along with capability to be used as contrast agent for MRI & CT. Copyright © 2017 Elsevier B.V. All rights reserved.

Direct electrochemical oxidation of S-captopril using gold electrodes modified with graphene-AuAg nanocomposites

PubMed Central

Pogacean, Florina; Biris, Alexandru R; Coros, Maria; Lazar, Mihaela Diana; Watanabe, Fumiya; Kannarpady, Ganesh K; Al Said, Said A Farha; Biris, Alexandru S; Pruneanu, Stela

2014-01-01

In this paper, we present a novel approach for the electrochemical detection of S-captopril based on graphene AuAg nanostructures used to modify an Au electrode. Multi-layer graphene (Gr) sheets decorated with embedded bimetallic AuAg nanoparticles were successfully synthesized catalytically with methane as the carbon source. The two catalytic systems contained 1.0 wt% Ag and 1.0 wt% Au, while the second had a larger concentration of metals (1.5 wt% Ag and 1.5 wt% Au) and was used for the synthesis of the Gr-AuAg-1 and Gr-AuAg-1.5 multicomponent samples. High-resolution transmission electron microscopy analysis indicated the presence of graphene flakes that had regular shapes (square or rectangular) and dimensions in the tens to hundreds of nanometers. We found that the size of the embedded AuAg nanoparticles varied between 5 and 100 nm, with the majority being smaller than 20 nm. Advanced scanning transmission electron microscopy studies indicated a bimetallic characteristic of the metallic clusters. The resulting Gr-AuAg-1 and Gr-AuAg-1.5 samples were used to modify the surface of commonly used Au substrates and subsequently employed for the direct electrochemical oxidation of S-captopril. By comparing the differential pulse voltammograms recorded with the two modified electrodes at various concentrations of captopril, the peak current was determined to be well-defined, even at relatively low concentration (10−5 M), for the Au/Gr-AuAg-1.5 electrode. In contrast, the signals recorded with the Au/Gr-AuAg-1 electrode were poorly defined within a 5×10−6 to 5×10−3 M concentration range, and many of them overlapped with the background. Such composite materials could find significant applications in nanotechnology, sensing, or nanomedicine. PMID:24596464

Fungus mediated synthesis of biomedically important cerium oxide nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khan, Shadab Ali; Ahmad, Absar, E-mail: a.ahmad@ncl.res.in

2013-10-15

Graphical abstract: - Highlights: • First time biological synthesis of cerium oxide oxide nanoparticles using fungus Humicola sp. • Complete characterization of cerium oxide nanoparticles. • Biosynthesis of naturally protein capped, luminescent and water dispersible CeO{sub 2} nanoparticles. • Biosynthesized CeO{sub 2} nanoparticles can be used for many biomedical applications. - Abstract: Nanomaterials can be synthesized by chemical, physical and the more recently discovered biological routes. The biological routes are advantageous over the chemical and physical ones as unlike these, the biological synthesis protocols occur at ambient conditions, are cheap, non-toxic and eco-friendly. Although purely biological and bioinspired methods formore » the synthesis of nanomaterials are environmentally benign and energy conserving processes, their true potential has not been explored yet and attempts are being made to extend the formation of technologically important nanoparticles using microorganisms like fungi. Though there have been reports on the biosynthesis of oxide nanoparticles by our group in the past, no attempts have been made to employ fungi for the synthesis of nanoparticles of rare earth metals or lanthanides. Here we report for the first time, the bio-inspired synthesis of biomedically important cerium oxide (CeO{sub 2}) nanoparticles using the thermophilic fungus Humicola sp. The fungus Humicola sp. when exposed to aqueous solutions of oxide precursor cerium (III) nitrate hexahydrate (CeN{sub 3}O{sub 9}·6H{sub 2}O) results in the extracellular formation of CeO{sub 2} nanoparticles containing Ce (III) and Ce (IV) mixed oxidation states, confirmed by X-ray Photoemission Spectroscopy (XPS). The formed nanoparticles are naturally capped by proteins secreted by the fungus and thus do not agglomerate, are highly stable, water dispersible and are highly fluorescent as well. The biosynthesized nanoparticles were characterized by UV–vis spectroscopy, Photoluminescence spectroscopy (PL), Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD) and X-ray Photoemission Spectroscopy (XPS)« less

Boosting photocatalytic overall water splitting by Co doping into Mn3O4 nanoparticles as oxygen evolution cocatalysts.

PubMed

Yoshinaga, Taizo; Saruyama, Masaki; Xiong, Anke; Ham, Yeilin; Kuang, Yongbo; Niishiro, Ryo; Akiyama, Seiji; Sakamoto, Masanori; Hisatomi, Takashi; Domen, Kazunari; Teranishi, Toshiharu

2018-06-14

The effect of cobalt doping into a manganese oxide (tetragonal spinel Mn 3 O 4 ) nanoparticle cocatalyst up to Co/(Co + Mn) = 0.4 (mol/mol) on the activity of photocatalytic water oxidation was studied. Monodisperse ∼10 nm Co y Mn 1-y O (0 ≤y≤ 0.4) nanoparticles were uniformly loaded onto photocatalysts and converted to Co x Mn 3-x O 4 nanoparticles through calcination. 40 mol% cobalt-doped Mn 3 O 4 nanoparticle-loaded Rh@Cr 2 O 3 /SrTiO 3 photocatalyst exhibited 1.8 times-higher overall water splitting activity than that with pure Mn 3 O 4 nanoparticles. Investigation on the band structure and electrocatalytic water oxidation activity of Co x Mn 3-x O 4 nanoparticles revealed that the Co doping mainly contributes to the improvement of water oxidation kinetics on the surface of the cocatalyst nanoparticles.

Pulsed—Laser Deposition Of Oxide Thin Films And Laser—Induced Breakdown Spectroscopy Of Multi—Element Materials

NASA Astrophysics Data System (ADS)

Pedarnig, Johannes D.

2010-10-01

New results of the Linz group on pulsed—laser deposition (PLD) of oxide thin films and on laser—induced breakdown spectroscopy (LIBS) of multi-element materials are reported. High-Tc superconducting (HTS) films with enhanced critical current density Jc are produced by laser ablation of novel nano-composite ceramic targets. The targets contain insulating nano-particles that are embedded into the YBa2Cu3O7 matrix. Epitaxial double-layers of lithium-doped and aluminum-doped ZnO are deposited on r-cut sapphire substrates. Acoustic over-modes in the GHz range are excited by piezoelectric actuation of layers. Smooth films of rare-earth doped glass are produced by F2—laser ablation. The transport properties of HTS thin films are modified by light—ion irradiation. Thin film nano—patterning is achieved by masked ion beam irradiation. LIBS is employed to analyze trace elements in industrial iron oxide powder and reference polymer materials. Various trace elements of ppm concentration are measured in the UV/VIS and vacuum-UV spectral range. Quantitative LIBS analysis of major components in oxide materials is performed by calibration-free methods.

Shape-Controlled Synthesis of Magnetic Iron Oxide@SiO₂-Au@C Particles with Core-Shell Nanostructures.

PubMed

Li, Mo; Li, Xiangcun; Qi, Xinhong; Luo, Fan; He, Gaohong

2015-05-12

The preparation of nonspherical magnetic core-shell nanostructures with uniform sizes still remains a challenge. In this study, magnetic iron oxide@SiO2-Au@C particles with different shapes, such as pseduocube, ellipsoid, and peanut, were synthesized using hematite as templates and precursors of magnetic iron oxide. The as-obtained magnetic particles demonstrated uniform sizes, shapes, and well-designed core-shell nanostructures. Transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX) analysis showed that the Au nanoparticles (AuNPs) of ∼6 nm were uniformly distributed between the silica and carbon layers. The embedding of the metal nanocrystals into the two different layers prevented the aggregation and reduced the loss of the metal nanocrystals during recycling. Catalytic performance of the peanut-like particles kept almost unchanged without a noticeable decrease in the reduction of 4-nitrophenol (4-NP) in 8 min even after 7 cycles, indicating excellent reusability of the particles. Moreover, the catalyst could be readily recycled magnetically after each reduction by an external magnetic field.

Dispersion and surface functionalization of oxide nanoparticles for transparent photocatalytic and UV-protecting coatings and sunscreens

NASA Astrophysics Data System (ADS)

Faure, Bertrand; Salazar-Alvarez, German; Ahniyaz, Anwar; Villaluenga, Irune; Berriozabal, Gemma; De Miguel, Yolanda R.; Bergström, Lennart

2013-04-01

This review describes recent efforts on the synthesis, dispersion and surface functionalization of the three dominating oxide nanoparticles used for photocatalytic, UV-blocking and sunscreen applications: titania, zinc oxide, and ceria. The gas phase and liquid phase synthesis is described briefly and examples are given of how weakly aggregated photocatalytic or UV-absorbing oxide nanoparticles with different composition, morphology and size can be generated. The principles of deagglomeration are reviewed and the specific challenges for nanoparticles highlighted. The stabilization of oxide nanoparticles in both aqueous and non-aqueous media requires a good understanding of the magnitude of the interparticle forces and the surface chemistry of the materials. Quantitative estimates of the Hamaker constants in various media and measurements of the isoelectric points for the different oxide nanoparticles are presented together with an overview of different additives used to prepare stable dispersions. The structural and chemical requirements and the various routes to produce transparent photocatalytic and nanoparticle-based UV-protecting coatings, and UV-blocking sunscreens are described and discussed.

Dispersion and surface functionalization of oxide nanoparticles for transparent photocatalytic and UV-protecting coatings and sunscreens

PubMed Central

Faure, Bertrand; Salazar-Alvarez, German; Ahniyaz, Anwar; Villaluenga, Irune; Berriozabal, Gemma; De Miguel, Yolanda R; Bergström, Lennart

2013-01-01

This review describes recent efforts on the synthesis, dispersion and surface functionalization of the three dominating oxide nanoparticles used for photocatalytic, UV-blocking and sunscreen applications: titania, zinc oxide, and ceria. The gas phase and liquid phase synthesis is described briefly and examples are given of how weakly aggregated photocatalytic or UV-absorbing oxide nanoparticles with different composition, morphology and size can be generated. The principles of deagglomeration are reviewed and the specific challenges for nanoparticles highlighted. The stabilization of oxide nanoparticles in both aqueous and non-aqueous media requires a good understanding of the magnitude of the interparticle forces and the surface chemistry of the materials. Quantitative estimates of the Hamaker constants in various media and measurements of the isoelectric points for the different oxide nanoparticles are presented together with an overview of different additives used to prepare stable dispersions. The structural and chemical requirements and the various routes to produce transparent photocatalytic and nanoparticle-based UV-protecting coatings, and UV-blocking sunscreens are described and discussed. PMID:27877568

Enhanced photoelectrochemical response of plasmonic Au embedded BiVO4/Fe2O3 heterojunction.

PubMed

Verma, Anuradha; Srivastav, Anupam; Khan, Saif A; Rani Satsangi, Vibha; Shrivastav, Rohit; Kumar Avasthi, Devesh; Dass, Sahab

2017-06-14

The effect of embedding Au nanoparticles (NPs) in a BiVO 4 /Fe 2 O 3 heterojunction for photoelectrochemical water splitting is studied here for the first time. The present nanostructured heterojunction offers three major advantages over pristine BiVO 4 and Fe 2 O 3 : (i) the formation of a heterojunction between BiVO 4 and Fe 2 O 3 enhances the charge carrier separation and transfer, (ii) the layer of Fe 2 O 3 provides protection to BiVO 4 from photocorrosion and, (iii) the Au NPs possessing surface plasmon resonance (SPR) enhance the photoelectrochemical response by transferring energy to metal oxides by hot electron transfer (HET) and plasmon resonant energy transfer (PRET). The present study reveals that the heterojunction ITO/BiVO 4 /Fe 2 O 3 (with 32% v/v Au solution in both layers) gives the best performance and mitigates the limitations of both pristine Fe 2 O 3 and BiVO 4 . A thirteen-fold increment in applied bias photon-to-current conversion efficiency (ABPE) was observed at 1.24 V vs. RHE under the condition of 1 Sun illumination. Monochromatic incident photon-to-current conversion efficiency (IPCE) measurements indicated that an Au embedded heterojunction is more effective in harvesting visible light in comparison to a heterojunction without Au NPs.

Configuration of twins in glass-embedded silver nanoparticles of various origin

NASA Astrophysics Data System (ADS)

Hofmeister, H.; Dubiel, M.; Tan, G. L.; Schicke, K.-D.

2005-09-01

Structural characterization using high resolution electron microscopy and diffractogram analysis of silver nanoparticles embedded in glass by various routes of fabrication was aimed at revealing the characteristic features of twin faults occuring in such particles. Nearly spherical silver nanoparticles well below 10 nm size embedded in commercial soda-lime silicate float glass have been fabricated either by silver/sodium ion exchange or by Ag+ ion implantation. Twinned nanoparticles, besides single crystalline species, have frequently been observed for both fabrication routes, mainly at sizes above 5 nm, but also at smaller sizes, even around 1 nm. The variety of particle forms comprises single crystalline particles of nearly cuboctahedron shape, particles containing single twin faults, and multiply twinned particles containing parallel twin lamellae, or cyclic twinned segments arranged around axes of fivefold symmetry. Parallel twinning is distinctly favoured by ion implantation whereas cyclic twinning preferably occurs upon ion exchange processing. Regardless of single or repeated twinning, parallel or cyclic twin arrangement, one may classify simple twin faults of regular atomic configuration and compound twin faults whose irregular configuration consists of additional planar defects like associated stacking faults or secondary twin faults. Besides, a particular superstructure composed of parallel twin lamellae of only three atomic layers thickness is observed.

Fabrication and characterization of copper oxide (CuO)–gold (Au)–titania (TiO{sub 2}) and copper oxide (CuO)–gold (Au)–indium tin oxide (ITO) nanowire heterostructures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chopra, Nitin, E-mail: nchopra@eng.ua.edu; Department of Biological Sciences, The University of Alabama, Tuscaloosa, AL 35487; Shi, Wenwu

2014-10-15

Nanoscale heterostructures composed of standing copper oxide nanowires decorated with Au nanoparticles and shells of titania and indium tin oxide were fabricated. The fabrication process involved surfactant-free and wet-chemical nucleation of gold nanoparticles on copper oxide nanowires followed by a line-of-sight sputtering of titania or indium tin oxide. The heterostructures were characterized using high resolution electron microscopy, diffraction, and energy dispersive spectroscopy. The interfaces, morphologies, crystallinity, phases, and chemical compositions were analyzed. The process of direct nucleation of gold nanoparticles on copper oxide nanoparticles resulted in low energy interface with aligned lattice for both the components. Coatings of polycrystalline titaniamore » or amorphous indium tin oxide were deposited on standing copper oxide nanowire–gold nanoparticle heterostructures. Self-shadowing effect due to standing nanowire heterostructures was observed for line-of-sight sputter deposition of titania or indium tin oxide coatings. Finally, the heterostructures were studied using Raman spectroscopy and ultraviolet–visible spectroscopy, including band gap energy analysis. Tailing in the band gap energy at longer wavelengths (or lower energies) was observed for the nanowire heterostructures. - Highlights: • Heterostructures comprised of CuO nanowires coated with Au nanoparticles. • Au nanoparticles exhibited nearly flat and low energy interface with nanowire. • Heterostructures were further sputter-coated with oxide shell of TiO{sub 2} or ITO. • The process resulted in coating of polycrystalline TiO{sub 2} and amorphous ITO shell.« less

Biosynthesis of silver and zinc oxide nanoparticles using Pichia fermentans JA2 and their antimicrobial property

NASA Astrophysics Data System (ADS)

Chauhan, Ritika; Reddy, Arpita; Abraham, Jayanthi

2015-01-01

The development of eco-friendly alternative to chemical synthesis of metal nanoparticles is of great challenge among researchers. The present study aimed to investigate the biological synthesis, characterization, antimicrobial study and synergistic effect of silver and zinc oxide nanoparticles against clinical pathogens using Pichia fermentans JA2. The extracellular biosynthesis of silver and zinc oxide nanoparticles was investigated using Pichia fermentans JA2 isolated from spoiled fruit pulp bought in Vellore local market. The crystalline and stable metallic nanoparticles were characterized evolving several analytical techniques including UV-visible spectrophotometer, X-ray diffraction pattern analysis and FE-scanning electron microscope with EDX-analysis. The biosynthesized metallic nanoparticles were tested for their antimicrobial property against medically important Gram positive, Gram negative and fungal pathogenic microorganisms. Furthermore, the biosynthesized nanoparticles were also evaluated for their increased antimicrobial activities with various commercially available antibiotics against clinical pathogens. The biosynthesized silver nanoparticles inhibited most of the Gram negative clinical pathogens, whereas zinc oxide nanoparticles were able to inhibit only Pseudomonas aeruginosa. The combined effect of standard antibiotic disc and biosynthesized metallic nanoparticles enhanced the inhibitory effect against clinical pathogens. The biological synthesis of silver and zinc oxide nanoparticles is a novel and cost-effective approach over harmful chemical synthesis techniques. The metallic nanoparticles synthesized using Pichia fermentans JA2 possess potent inhibitory effect that offers valuable contribution to pharmaceutical associations.

Conducting metal oxide and metal nitride nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

DiSalvo, Jr., Francis J.; Subban, Chinmayee V.

Conducting metal oxide and nitride nanoparticles that can be used in fuel cell applications. The metal oxide nanoparticles are comprised of for example, titanium, niobium, tantalum, tungsten and combinations thereof. The metal nitride nanoparticles are comprised of, for example, titanium, niobium, tantalum, tungsten, zirconium, and combinations thereof. The nanoparticles can be sintered to provide conducting porous agglomerates of the nanoparticles which can be used as a catalyst support in fuel cell applications. Further, platinum nanoparticles, for example, can be deposited on the agglomerates to provide a material that can be used as both an anode and a cathode catalyst supportmore » in a fuel cell.« less

The interfacial orientation relationship of oxide nanoparticles in a hafnium-containing oxide dispersion-strengthened austenitic stainless steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miao, Yinbin, E-mail: miao2@illinois.edu; Mo, Kun; Cui, Bai

2015-03-15

This work reports comprehensive investigations on the orientation relationship of the oxide nanoparticles in a hafnium-containing austenitic oxide dispersion-strengthened 316 stainless steel. The phases of the oxide nanoparticles were determined by a combination of scanning transmission electron microscopy–electron dispersive X-ray spectroscopy, atom probe tomography and synchrotron X-ray diffraction to be complex Y–Ti–Hf–O compounds with similar crystal structures, including bixbyite Y{sub 2}O{sub 3}, fluorite Y{sub 2}O{sub 3}–HfO{sub 2} solid solution and pyrochlore (or fluorite) Y{sub 2}(Ti,Hf){sub 2−x}O{sub 7−x}. High resolution transmission electron microscopy was used to characterize the particle–matrix interfaces. Two different coherency relationships along with one axis-parallel relation between themore » oxide nanoparticles and the steel matrix were found. The size of the nanoparticles significantly influences the orientation relationship. The results provide insight into the relationship of these nanoparticles with the matrix, which has implications for interpreting material properties as well as responses to radiation. - Highlights: • The oxide nanoparticles in a hafnium-containing austenitic ODS were characterized. • The nanoparticles are Y–Hf–Ti–O enriched phases according to APT and STEM–EDS. • Two coherency and an axis-parallel orientation relationships were found by HR-TEM. • Particle size has a prominent effect on the orientation relationship (OR). • Formation mechanism of the oxide nanoparticles was discussed based on the ORs.« less

Can microbes mediate nano-transformation?

NASA Astrophysics Data System (ADS)

Prasad, K.; Jha, Anal K.; Prasad, Kamlesh; Kulkarni, A. R.

2010-10-01

A green low-cost and reproducible microbe ( Lactobacillus) and baker's yeast ( Saccharomyces cerevisiae) mediated biosynthesis of metallic and oxide nanoparticles are reported. Silver and copper oxide nanoparticles are synthesized using Lactobacillus sp. and Saccharomyces cerevisiae. The synthesis is performed akin to room temperature in the laboratory ambience. X-ray and transmission electron microscopy analyses are performed to ascertain the formation of metallic and oxide nanoparticles. Individual nanoparticles having the dimensions of 2-6 nm (metallic) and 10-20 nm (oxide) are found. A possible mechanism involved for the synthesis of metallic and oxide nanoparticles has also been proposed in which pH as well as the partial pressure of gaseous hydrogen (r-H2) or redox potential of the culture solution seem to play an important role in the process.

Silver nanoparticles as a key feature of a plasma polymer composite layer in mitigation of charge injection into polyethylene under dc stress

NASA Astrophysics Data System (ADS)

Milliere, L.; Maskasheva, K.; Laurent, C.; Despax, B.; Boudou, L.; Teyssedre, G.

2016-01-01

The aim of this work is to limit charge injection from a semi-conducting electrode into low density polyethylene (LDPE) under dc field by tailoring the polymer surface using a silver nanoparticles-containing layer. The layer is composed of a plane of silver nanoparticles embedded in a semi-insulating organosilicon matrix deposited on the polyethylene surface by a plasma process. Size, density and surface coverage of the nanoparticles are controlled through the plasma process. Space charge distribution in 300 μm thick LDPE samples is measured by the pulsed-electroacoustic technique following a short term (step-wise voltage increase up to 50 kV mm-1, 20 min in duration each, followed by a polarity inversion) and a longer term (up to 12 h under 40 kV mm-1) protocols for voltage application. A comparative study of space charge distribution between a reference polyethylene sample and the tailored samples is presented. It is shown that the barrier effect depends on the size distribution and the surface area covered by the nanoparticles: 15 nm (average size) silver nanoparticles with a high surface density but still not percolating form an efficient barrier layer that suppress charge injection. It is worthy to note that charge injection is detected for samples tailored with (i) percolating nanoparticles embedded in organosilicon layer; (ii) with organosilicon layer only, without nanoparticles and (iii) with smaller size silver particles (<10 nm) embedded in organosilicon layer. The amount of injected charges in the tailored samples increases gradually in the samples ranking given above. The mechanism of charge injection mitigation is discussed on the basis of complementary experiments carried out on the nanocomposite layer such as surface potential measurements. The ability of silver clusters to stabilize electrical charges close to the electrode thereby counterbalancing the applied field appears to be a key factor in explaining the charge injection mitigation effect.

Structural characterization, antibacterial and catalytic effect of iron oxide nanoparticles synthesised using the leaf extract of Cynometra ramiflora

NASA Astrophysics Data System (ADS)

Groiss, Silvia; Selvaraj, Raja; Varadavenkatesan, Thivaharan; Vinayagam, Ramesh

2017-01-01

In the present investigation, the leaf extract of Cynometra ramiflora was used to synthesize iron oxide nanoparticles. Within minutes of adding iron sulphate to the leaf extract, iron oxide nanoparticles were formed and thus, the method is very simple and fast. UV-VIS spectra showed the strong absorption band in the visible region. SEM images showed discrete spherical shaped particles and EDS spectra confirmed the iron and oxygen presence. The XRD results depicted the crystalline structure of iron oxide nanoparticles. FT-IR spectra portrayed the existence of functional groups of phytochemicals which are probably involved in the formation and stabilization of nanoparticles. The iron oxide nanoparticles exhibited effective inhibition against E. coli and S. epidermidis which may find its applications in the antibacterial drug development. Furthermore, the catalytic activity of the nanoparticles as Fenton-like catalyst was successfully investigated for the degradation of Rhodamine-B dye. This outcome could play a prominent role in the wastewater treatment.

Nanostructures based on alumina hydroxides inhibit tumor growth

NASA Astrophysics Data System (ADS)

Fomenko, A. N.; Korovin, M. S.

2017-09-01

Nanoparticles and nanostructured materials are one of the most promising developments for cancer therapy. Gold nanoparticles, magnetic nanoparticles based on iron and its oxides and other metal oxides have been widely used in diagnosis and treatment of cancer. Much less research attention has been payed to nanoparticles and nanostructures based on aluminum oxides and hydroxides as materials for cancer diagnosis and treatment. However recent investigations have shown promising results regarding these objects. Here, we review the antitumor results obtained with AlOOH nanoparticles.

Green synthesis of colloidal copper oxide nanoparticles using Carica papaya and its application in photocatalytic dye degradation.

PubMed

Sankar, Renu; Manikandan, Perumal; Malarvizhi, Viswanathan; Fathima, Tajudeennasrin; Shivashangari, Kanchi Subramanian; Ravikumar, Vilwanathan

2014-01-01

Copper oxide (CuO) nanoparticles were synthesized by treating 5 mM cupric sulphate with Carica papaya leaves extract. The kinetics of the reaction was studied using UV-visible spectrophotometry. An intense surface Plasmon resonance between 250-300 nm in the UV-vis spectrum clearly reveals the formation of copper oxide nanoparticles. The results of scanning electron microscopy (SEM) and dynamic light scattering (DLS) exhibited that the green synthesized copper oxide nanoparticles are rod in shape and having a mean particle size of 140 nm, further negative zeta potential disclose its stability at -28.9 mV. The Fourier-transform infrared (FTIR) spectroscopy results examined the occurrence of bioactive functional groups required for the reduction of copper ions. X-ray diffraction (XRD) spectra confirmed the copper oxide nanoparticles crystalline nature. Furthermore, colloidal copper oxide nanoparticles effectively degrade the Coomassie brilliant blue R-250 dye beneath the sunlight. Copyright © 2013 Elsevier B.V. All rights reserved.

Immobilization of bacterial S-layer proteins from Caulobacter crescentus on iron oxide-based nanocomposite: synthesis and spectroscopic characterization of zincite-coated Fe₂O₃ nanoparticles.

PubMed

Habibi, Neda

2014-05-05

Zinc oxide was coated on Fe2O3 nanoparticles using sol-gel spin-coating. Caulobacter crescentus have a crystalline surface layer (S-layer), which consist of one protein or glycoprotein species. The immobilization of bacterial S-layers obtained from C. crescentus on zincite-coated nanoparticles of iron oxide was investigated. The SDS PAGE results of S-layers isolated from C. crescentus showed the weight of 50 KDa. Nanoparticles of the Fe2O3 and zinc oxide were synthesized by a sol-gel technique. Fe2O3 nanoparticles with an average size of 50 nm were successfully prepared by the proper deposition of zinc oxide onto iron oxide nanoparticles surface annealed at 450 °C. The samples were characterized by field-emission scanning electron microscope (FESEM), atomic force microscopy (AFM), powder X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR). Copyright © 2014 Elsevier B.V. All rights reserved.

Solution Plasma-assisted Bimetallic Oxide Alloy Nanoparticles of Pt and Pd Embedded within Two-dimensional Ti3C2Tx Nanosheets as Highly Active Electrocatalysts for Overall Water-splitting.

PubMed

Cui, Bingbing; Hu, Bin; Liu, Jiameng; Wang, Minghua; Song, Yingpan; Tian, Kuan; Zhang, Zhihong; He, Linghao

2018-06-25

Exploiting high-efficiency and low-cost bifunctional electrocatalysts for hydrogen evolution (HER) and oxygen evolution reactions (OER) has been actively encouraged because of their potential applications in the field of clean energy. In this paper, we reported a novel electrocatalyst based on an exfoliated two-dimensional (2D) MXene (Ti3C2Tx) loaded with bimetallic oxide alloy nanoparticles (NPs) of Pt and Pd (represented by PtOaPdObNPs@Ti3C2Tx), which was synthesized via solution plasma (SP) modification. The prepared materials were then utilized as highly efficient bifunctional electrocatalysts toward HER and OER in alkaline solution. At a high plasma input power (200 W), bimetallic oxide alloy nanoparticles of Pt and Pd or nanoclusters with different metallic valence states deposited onto the Ti3C2Tx nanosheets. Due to the synergism of the noble metal NPs and the Ti3C2Tx nanosheets, the electrocatalytic results revealed that the as-prepared PtOaPdObNPs@Ti3C2Tx nanosheets under the plasma input power of 200 W for 3 min catalyst only required a low overpotential to attain 10 mA cm-2 for HER (57 mV) in 0.5 M H2SO4 solution and OER (1.63 V) in 0.1 M KOH sollution. Moreover, water electrolysis using this catalyst achieved a water splitting current density of 10 mA cm-2 at a low cell voltage of 1.53 V in 1.0 M KOH solution. These results suggested that the hybridization of the ultra-extremely low usage of PtOa/PdOb NPs (1.07 μg cm-2) and Ti3C2Tx nanosheets by SP will expand the applications of other clean energy reactions to achieve sustainable energy.

Shape control of the magnetic iron oxide nanoparticles under different chain length of reducing agents

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ngoi, Kuan Hoon; Chia, Chin-Hua, E-mail: chia@ukm.edu.my; Zakaria, Sarani

2015-09-25

We report on the effect of using reducing agents with different chain-length on the synthesis of iron oxide nanoparticles by thermal decomposition of iron (III) acetylacetonate in 1-octadecene. This modification allows us to control the shape of nanoparticles into spherical and cubic iron oxide nanoparticles. The highly monodisperse 14 nm spherical nanoparticles are obtained under 1,2-dodecanediol and average 14 nm edge-length cubic iron oxide nanoparticles are obtained under 1,2-tetradecanediol. The structural characterization such as transmission electron microscope (TEM) and X-ray diffraction (XRD) shows similar properties between two particles with different shapes. The vibrating sample magnetometer (VSM) shows no significant difference between sphericalmore » and cubic nanoparticles, which are 36 emu/g and 37 emu/g respectively and superparamagnetic in nature.« less

Size-dependent cytotoxicity of yttrium oxide nanoparticles on primary osteoblasts in vitro

NASA Astrophysics Data System (ADS)

Zhou, Guoqiang; Li, Yunfei; Ma, Yanyan; Liu, Zhu; Cao, Lili; Wang, Da; Liu, Sudan; Xu, Wenshi; Wang, Wenying

2016-05-01

Yttrium oxide nanoparticles are an excellent host material for the rare earth metals and have high luminescence efficiency providing a potential application in photodynamic therapy and biological imaging. In this study, the effects of yttrium oxide nanoparticles with four different sizes were investigated using primary osteoblasts in vitro. The results demonstrated that the cytotoxicity generated by yttrium oxide nanoparticles depended on the particle size, and smaller particles possessed higher toxicological effects. For the purpose to elucidate the relationship between reactive oxygen species generation and cell damage, cytomembrane integrity, intracellular reactive oxygen species level, mitochondrial membrane potential, cell apoptosis rate, and activity of caspase-3 in cells were then measured. Increased reactive oxygen species level was also observed in a size-dependent way. Thus, our data demonstrated that exposure to yttrium oxide nanoparticles resulted in a size-dependent cytotoxicity in cultured primary osteoblasts, and reactive oxygen species generation should be one possible damage pathway for the toxicological effects produced by yttrium oxide particles. The results may provide useful information for more rational applications of yttrium oxide nanoparticles in the future.

Preparation of PVA/Co/Ag film and evaluation of its magnetic and microstructural properties

NASA Astrophysics Data System (ADS)

Banerjee, M.; Sachdev, Preeti; Mukherjee, G. S.

2012-05-01

PVA/Co/Ag film has been prepared by sputtering Co followed by Ag in polyvinyl alcohol (PVA) matrix film by IBS technique, so as to get a 9 nm (thick) layer of Co metal nanoparticles followed by a protective 4 nm (thick) layer of Ag nanoparticles. Grazing incidence x-ray diffraction (GIXRD) pattern of the film reveals the formation of nanocrystalline Co with hcp phase. GIXRD pattern also indicates that there is no change in the crystalline structure of PVA even after sputtering of the metallic nanoparticles. The average particle size of Co nanoparticles as evaluated using Scherrer formula is found to be about 2.64 nm. UV visible absorption pattern of the film sample showed SPR peaks of Co and Ag metals in their nano size level embedded in the PVA matrix system. XPS study confirms the metallic nature of Co and Ag nanoparticles; and the depth profiling study reveals that both the metal nanoparticles have been embedded in the PVA matrix system. Surface morphology of such film has been studied using AFM; and the magnetic behaviour of the film studied by using MOKE shows soft ferromagnetic behaviour in this PVA/Co/Ag system.

Design of Fucoidan Functionalized - Iron Oxide Nanoparticles for Biomedical Applications.

PubMed

Tran, Khanh Nghia; Tran, Phuong Ha-Lien; Vo, Toi Van; Tran, Thao Truong-Dinh

2016-01-01

This research aims to develop an iron oxide nanoparticle drug delivery system utilizing a recent material discovered from ocean, fucoidan. The material has drawn much interest due to many biomedical functions that have been proven for human health. One interesting point herein is that fucoidan is not only a sulfated polysaccharide, a polymer for stabilization of iron oxide nanoparticles, but plays a role of an anticancer agent also. Various approaches were investigated to optimize the high loading efficiency and explain the mechanism of nanoparticle formations. Fucoidan was functionalized on iron oxide nanoparticles by a direct coating or via amine groups. Also, a hydrophobic part of oleic acid was conjugated to the amine groups for a more favorable loading of poorly water-soluble anticancer drugs. This study proposed a novel system and an efficient method to functionalize fucoidan on iron oxide nanoparticle systems which will lead to a facilitation of a double strength treatment of cancer.

Confinement boosts CO oxidation on an Ni atom embedded inside boron nitride nanotubes

DOE PAGES

Zhang, Yadong; Liu, Yuzhen; Meng, Zhaoshun; ...

2018-01-01

Because of the confinement effect, Ni embedded on the interior surface of BNNT exhibits a much higher catalytic activity for CO oxidation by comparing with that embedded in h-BN or on the outside surface of BNNT.

PdCo alloy nanoparticle-embedded carbon nanofiber for ultrasensitive nonenzymatic detection of hydrogen peroxide and nitrite.

PubMed

Liu, Dong; Guo, Qiaohui; Zhang, Xueping; Hou, Haoqing; You, Tianyan

2015-07-15

PdCo alloy nanoparticle-embedded carbon nanofiber (PdCo/CNF) prepared by electrospinning and thermal treatment was employed as a high-performance platform for the determination of hydrogen peroxide and nitrite. The as-obtained PdCo/CNF were characterized by transmission electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction. Electrochemical impedance spectroscopy, cyclic voltammetry and differential pulse voltammetry were employed to investigate the electrochemical behaviors of the resultant biosensor. The proposed PdCo/CNF-based biosensor showed excellent analytical performances toward hydrogen peroxide (detection limit: 0.1 μM; linear range: 0.2 μM-23.5 mM) and nitrite (detection limit: 0.2 μM; linear range: 0.4-30 μM and 30-400 μM). The superior analytical properties could be attributed to the synergic effect and firmly embedment of well-dispersed PdCo alloy nanoparticles. These attractive electrochemical properties make this robust electrode material promising for the development of effective electrochemical sensors. Copyright © 2015 Elsevier Inc. All rights reserved.

Heteroaggregation of cerium oxide nanoparticles and nanoparticles of pyrolyzed biomass

USDA-ARS?s Scientific Manuscript database

Heteroaggregation with indigenous particles is an important process controlling the mobility of engineered nanomaterials in the environment. We studied heteroaggregation of cerium oxide nanoparticles (n-CeO2), which are widely used commercially, with nanoparticles of pyrogenic carbonaceous material ...

Electrocatalytic performance of Pt nanoparticles sputter-deposited on indium tin oxide toward methanol oxidation reaction: The particle size effect

NASA Astrophysics Data System (ADS)

Ting, Chao-Cheng; Chao, Chih-Hsuan; Tsai, Cheng Yu; Cheng, I.-Kai; Pan, Fu-Ming

2017-09-01

We sputter-deposited Pt nanoparticles with an average size ranging from 2.0 nm to 8.5 nm on the indium-tin oxide (ITO) glass substrate, and studied the effect of the size of Pt nanoparticles on electrocatalytic activity of the Pt/ITO electrode toward methanol oxidation reaction (MOR) in acidic solution. X-ray photoelectron spectroscopy (XPS) reveals an interfacial oxidized Pt layer present between Pt nanoparticles and the ITO substrate, which may modify the surface electronic structure of Pt nanoparticles and thus influences the electrocatalytic properties of the Pt catalyst toward MOR. According to electrochemical analyses, smaller Pt nanoparticles exhibit slower kinetics for CO electrooxidation and MOR. However, a smaller particle size enables better CO tolerance because the bifunctional mechanism is more effective on smaller Pt nanoparticles. The electrocatalytic activity decays rapidly for Pt nanoparticles with a size smaller than 3 nm and larger than 8 nm. The rapid activity decay is attributed to Pt dissolution for smaller nanoparticles and to CO poisoning for larger ones. Pt nanoparticles of 5-6 nm in size loaded on ITO demonstrate a greatly improved electrocatalytic activity and stability compared with those deposited on different substrates in our previous studies.

Green Synthesis of Formulated Zinc Oxide Nanoparticles for Chemical Protection of Skin Care and Related Applications

NASA Astrophysics Data System (ADS)

Koppolu, Ramya

Nanomaterials have diversified applications based on the unique properties. These nanoparticles and functionalized nanocomposites have been studied in the health care filed. Nanoparticles are mostly used in sunscreens which are a part of human life. These sunscreens consist of titanium dioxide and zinc oxide nanoparticles. Due to the higher band crevices, they help the skin to protect from ultraviolet rays, for instance, ultraviolet B and ultraviolet A. A series of nanostructured zinc oxide nanoparticles were prepared by cost-effective chemical and bioinspired methods and variables were optimized. Highly stable and spherical zinc oxide nanoparticles were formulated by aloe vera ( Aloe barbadensis) plant extract and avocado (Persea americana Mill) fruit extract. The state-of-the-art instrumentation was used to characterize the morphology, elemental composition, and particle size distribution. X-ray diffraction data indicated highly crystalline and ultrafine nanoparticles were obtained from the colloidal methods. The X-ray photoelectron spectroscopy results showed the chemical state of zinc, carbon, and oxygen atoms were well-indexed and are used as fingerprint identification of the elements. Transmission electron microscopy images show the shape of particles were cubic and fiber shape contingent upon the protecting operators and heat treatment conditions. The toxicity studies of zinc oxide nanoparticles were found to cause an increase in nitric oxide, which is protecting against further oxidative stress and appears to be nontoxic.

Thermal effects on the structural properties of tungsten oxide nanoparticles

NASA Astrophysics Data System (ADS)

Yang, Tsung-Yeh; Wu, Chung-Yi; Tsai, Meng-Hung; Lin, Hong-Ming; Tsai, Wen-Li; Hwu, Yeukuang

2004-06-01

Tungsten oxide nanoparticles are prepared by evaporating and oxidizing the tungsten boat in helium and oxygen atmosphere and then quenched to the liquid nitrogen temperature. The as-prepared tungsten oxide nanoparticles are porous-free with uniform size. The morphology and particle size distribution of the as-prepared and after sinter treatments tungsten oxide nanoparticles are revealed by TEM and AFM. The long-range order of these nanoparticles can be examined by X-ray diffraction technique. The as-prepared nanoparticles exhibit a mixture structure of monoclinic and hexagonal crystals. Preliminary X-ray diffraction results indicate that the hexagonal structure is transformed to monoclinic structure after annealing to above 600°C. In order to better distinguish the structural properties of the tungsten oxide (WO3- x) nanoparticles before and after annealing, the X-ray absorption spectrum technique is utilized; thus, the detailed local atomic arrangement of oxygen and/or tungsten can be determined. According to the XAS result, the shape of the W L3-edge undergoes no considerable changes. This infers that structural transformation of tungsten oxide nanoparticle may be caused by the migration of oxygen after sintering. From the O K-edge of absorption spectrum, it suggests that a mixture phase structure is obtained when sintered below 300°C. And this result indicates that heat treatment to approximately 600°C produces a stable structure of a monoclinic crystal of WO3.

Optical absorption and TEM studies of silver nanoparticle embedded BaO-CaF{sub 2}-P{sub 2}O{sub 5} glasses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Narayanan, Manoj Kumar, E-mail: manukokkal01@gmail.com; Shashikala, H. D.

Silver nanoparticle embedded 30BaO-20CaF{sub 2}-50P{sub 2}O{sub 5}-4Ag{sub 2}O-4SnO glasses were prepared by melt-quenching and subsequent heat treatment process. Silver-doped glasses were heat treated at temperatures 500 °C, 525°C and 550 °C for a fixed duration of 10 hours to incorporate metal nanoparticles into the glass matrix. Appearance and shift in peak positions of the surface plasmon resonance (SPR) bands in the optical absorption spectra of heat treated glass samples indicated that both formation and growth of nanoparticle depended on heat treatment temperature. Glass sample heat treated at 525 °C showed a SPR peak around 3 eV, which indicated that sphericalmore » nanoparticles smaller than 20 nm were formed inside the glass matrix. Whereas sample heat treated at 550 °C showed a size dependent red shift in SPR peak due to the presence of silver nanoparticles of size larger than 20 nm. Size of the nanoparticles calculated using full-width at half-maximum (FWHM) of absorption band showed a good agreement with the particle size obtained from transmission electron microscopy (TEM) analysis.« less

Thermooptical properties of gold nanoparticles embedded in ice: characterization of heat generation and melting.

PubMed

Richardson, Hugh H; Hickman, Zackary N; Govorov, Alexander O; Thomas, Alyssa C; Zhang, Wei; Kordesch, Martin E

2006-04-01

We investigate the system of optically excited gold NPs in an ice matrix aiming to understand heat generation and melting processes at the nanoscale level. Along with the traditional fluorescence method, we introduce thermooptical spectroscopy based on phase transformation of a matrix. With this, we can not only measure optical response but also thermal response, that is, heat generation. After several recrystallization cycles, the nanoparticles are embedded into the ice film where the optical and thermal properties of the nanoparticles are probed. Spatial fluorescence mapping shows the locations of Au nanoparticles, whereas the time-resolved Raman signal of ice reveals the melting process. From the time-dependent Raman signals, we determine the critical light intensities at which the laser beam is able to melt ice around the nanoparticles. The melting intensity depends strongly on temperature and position. The position-dependence is especially strong and reflects a mesoscopic character of heat generation. We think that it comes from the fact that nanoparticles form small complexes of different geometry and each complex has a unique thermal response. Theoretical calculations and experimental data are combined to make a quantitative measure of the amount of heat generated by optically excited Au nanoparticles and agglomerates. The information obtained in this study can be used to design nanoscale heaters and actuators.

Enhanced Formation of Oxidants from Bimetallic Nickel-Iron Nanoparticles in the Presence of Oxygen

PubMed Central

Lee, Changha; Sedlak, David L.

2009-01-01

Nanoparticulate zero-valent iron (nZVI) rapidly reacts with oxygen to produce strong oxidants, capable of transforming organic contaminants in water. However, the low yield of oxidants with respect to the iron added normally limits the application of this system. Bimetallic nickel-iron nanoparticles (nNi-Fe; i.e., Ni-Fe alloy and Ni-coated Fe nanoparticles) exhibited enhanced yields of oxidants compared to nZVI. nNi-Fe (Ni-Fe alloy nanoparticles with [Ni]/[Fe] = 0.28 and Ni-coated Fe nanoparticles with [Ni]/[Fe] = 0.035) produced approximately 40% and 85% higher yields of formaldehyde from the oxidation of methanol relative to nZVI at pH 4 and 7, respectively. Ni-coated Fe nanoparticles showed a higher efficiency for oxidant production relative to Ni-Fe alloy nanoparticles based on Ni content. Addition of Ni did not enhance the oxidation of 2-propanol or benzoic acid, indicating that Ni addition did not enhance hydroxyl radical formation. The enhancement in oxidant yield was observed over a pH range of 4 – 9. The enhanced production of oxidant by nNi-Fe appears to be attributable to two factors. First, the nNi-Fe surface is less reactive toward hydrogen peroxide (H2O2) than the nZVI surface, which favors the reaction of H2O2 with dissolved Fe(II) (the Fenton reaction). Second, the nNi-Fe surface promotes oxidant production from the oxidation of ferrous ion by oxygen at neutral pH values. PMID:19068843

Visualizing the Cu/Cu2(O) Interface Transition in Nanoparticles with Environmental Scanning Transmission Electron Microscopy.

PubMed

LaGrow, Alec P; Ward, Michael R; Lloyd, David C; Gai, Pratibha L; Boyes, Edward D

2017-01-11

Understanding the oxidation and reduction mechanisms of catalytically active transition metal nanoparticles is important to improve their application in a variety of chemical processes. In nanocatalysis the nanoparticles can undergo oxidation or reduction in situ, and thus the redox species are not what are observed before and after reactions. We have used the novel environmental scanning transmission electron microscope (ESTEM) with 0.1 nm resolution in systematic studies of complex dynamic oxidation and reduction mechanisms of copper nanoparticles. The oxidation of copper has previously been reported to be dependent on its crystallography and its interaction with the substrate. By following the dynamic oxidation process in situ in real time with high-angle annular dark-field imaging in the ESTEM, we use conditions ideal to track the oxidation front as it progresses across a copper nanoparticle by following the changes in the atomic number (Z) contrast with time. The oxidation occurs via the nucleation of the oxide phase (Cu 2 O) from one area of the nanoparticle which then progresses unidirectionally across the particle, with the Cu-to-Cu 2 O interface having a relationship of Cu{111}//Cu 2 O{111}. The oxidation kinetics are related to the temperature and oxygen pressure. When the process is reversed in hydrogen, the reduction process is observed to be similar to the oxidation, with the same crystallographic relationship between the two phases. The dynamic observations provide unique insights into redox mechanisms which are important to understanding and controlling the oxidation and reduction of copper-based nanoparticles.

Electromagnetic properties of Fe-Co granular composite materials containing acicular nanoparticles

NASA Astrophysics Data System (ADS)

Kasagi, Teruhiro; Massango, Herieta; Tsutaoka, Takanori; Yamamoto, Shinichiro; Hatakeyama, Kenichi

2018-03-01

Electromagnetic properties of acicular (needle-like) Fe76Co24 nanoparticle composite materials have been studied in microwave frequency range up to 20 GHz. The Fe76Co24 particles are commercially available acicular Fe76Co24 nanoparticles with an approximate length and diameter of 100 and 25 nm, respectively. The Fe76Co24 nanocomposites were prepared by embedding the Fe76Co24 nanoparticle in an appropriate resin. Since the metallic Fe76Co24 nanoparticles have an oxidized surface, even high particle content composites at 78 vol.%, which is in the percolated state, does not show metallic conduction; a low frequency plasmonic state with the negative permittivity spectrum was not observed. Meanwhile, the negative permeability spectrum caused by the magnetic resonance in Fe76Co24 alloy was obtained in the high particle content composites. From the measurement of the complex permeability spectra under the external dc magnetic field, it was clarified that the gyromagnetic spin rotation mainly contributes to the permeability spectrum of nanocomposites due to extremely small quantity of domain walls in the acicular nanoparticles. This result suggests that the negative permeability spectrum was caused by the gyromagnetic spin resonance. By the comparison of the complex permeability spectrum between the acicular Fe76Co24 nanocomposite and the spherical Fe50Co50 microcomposite, the gyromagnetic spin resonance frequency of the acicular nanocomposite tends to locate higher than that of the spherical microcomposite owing to the demagnetizing field effect. Therefore, it can be concluded that the negative permeability frequency band of the acicular nanocomposite is higher than that of the spherical microcomposite at the same particle content.

The effect of coating on heat generation properties of Iron oxide nanoparticles

NASA Astrophysics Data System (ADS)

Yuan, Yuan

Magnetic nanoparticles have attracted more and more attention for their potential application as heating agents in cancer hyperthermia. The effectiveness of cancer hyperthermia can be increased by using particles that have a higher heat generation rate, quantified by specific absorption rate (SAR), at a smaller applied field. In order to optimize the functionality of nanoparticles as heating agents, it is essential to have a comprehensive understanding of factors that may influence SAR including coating and aggregation. In all biomedical applications, the magnetic particles are coated with surfactants and polymers to enhance biocompatibility, prevent agglomeration and add functionality. Coatings may profoundly influence particles' clustering behavior and magnetic properties. Yet its effect on the heat generation rate of the nanoparticles has been scarcely investigated. In this context, a systematic investigation was carried out in this dissertation in order to understand the impact of the surface coating of magnetic nanoparticles on their heat generation rate. The study also includes investigation of normal nerve cell viability in presence of biofunctionalized magnetic nanoparticles with and without exposure to magnetic heating. Commercially available suspensions of iron oxide nanoparticles with a diameter of approximately 10 nm and different coatings relevant to biomedical applications such as aminosilane, carboxymethyl-dextran, protein A, biotin were extensively characterized. First of all, magnetic phase reduction of magnetite nanoparticles was examined by studying the discrepancy between the volume fraction of magnetic phase calculated from magnetization curve and the magnetic core concentration obtained from Tiron chelation test. The findings indicated that coatings might interact with the surface atoms of the magnetic core and form a magnetically disordered layer reducing the total amount of the magnetic phase. Secondly, the impact of coating and aggregation on magnetic properties and heat generation rate of magnetic nanoparticles was investigated by comparing the experimental and predicted SAR. For this purpose, AC magnetic susceptibility of suspensions was measured and also calculated by Debye model. Both were used to predict SAR and then compare it to the measured SAR. Poor agreement was found when the predictions were based on the Debye model, which neglects dipolar interactions between nanoparticles within aggregations. For uncoated and amine-functionalized particles (with aggregations) experimental SAR was found to agree relatively well with predicted SAR using experimental susceptibility values, which is expected to capture magnetic losses. For biotin and protein A coated nanoparticles (both having large, asymmetric clusters), the experimental SAR of both samples was found to be higher than the SAR predicted with experimental susceptibility. This unexpected discrepancy was attributed in part to friction loss associated with the partial rotation of clusters. This hypothesis was confirmed by examining the temperature increasing rate of particles embeded in hydrogel with different stiffness. At last, the properties of magnetic nanoparticles dispersed in DI water, Neurobasal (NB), or astrocyte culture media were studied. The aminosilane coated nanoparticles that dispersed in astrocyte culture media presented highest susceptibility and SAR compared to that suspended in DI water or NB, which was attributed to its highest aggregation size and magnetization phase concentration. However, for starch coated nanoparticles, samples prepared in either media showed similar magnetic and heating properties. The cell studies started with investigation of the response of primary cortical neurons to magnetite nanoparticles with aminosilane, starch and polydimethylamine coatings. It was found that polydimethylamine functionalized nanoparticles induce cell death at all concentrations and complete removal of plasma membrane. Aminosilane and starch-coated particles affected metabolic activities only at higher concentrations while leaving the membrane intact. The iron oxide nanoparticle with aminosilane coating were then used to further study the response of neurons and astrocytes to local heat generated by magnetic nanoparticles. The culture results show that heating does not affect viability of neurons but influence the viability of astrocytes independent of final temperature.

Fabrication of Sb₂S₃ Hybrid Solar Cells Based on Embedded Photoelectrodes of Ag Nanowires-Au Nanoparticles Composite.

PubMed

Kim, Kang-Pil; Hwang, Dae-Kue; Woo, Sung-Ho; Kim, Dae-Hwan

2018-09-01

The Ag nanowire (NW) + Au nanoparticle (NP)-embedded TiO2 photoelectrodes were adopted for conventional planar TiO2-based Sb2S3 hybrid solar cells to improve the cell efficiency. Compared to conventional planar TiO2-based Sb2S3 hybrid solar cells, the Ag NW + Au NP/TiO2-based Sb2S3 hybrid solar cells exhibited an improvement of approximately 40% in the cell efficiency due to the significant increase in both Jsc and Voc. These enhanced Jsc and Voc were attributed to the increased surface area, charge-collection efficiency, and light absorption by embedding the Ag NWs + Au NPs composite. The Ag NW + Au NP/TiO2-based Sb2S3 hybrid solar cells showed the highest efficiency of 2.17%, demonstrating that the Ag NW + Au NP-embedded TiO2 photoelectrode was a suitable photoelectrode structure to improve the power conversion efficiency in the Sb2S3 hybrid solar cells.

Stability of Y-Ti-O nanoparticles during laser deposition of oxide dispersion strengthened steel powder

NASA Astrophysics Data System (ADS)

Euh, Kwangjun; Arkhurst, Barton; Kim, Il Hyun; Kim, Hyun-Gil; Kim, Jeoung Han

2017-11-01

This study investigated the feasibility of a direct energy deposition process for fabrication of oxide dispersion strengthened steel cladding. The effect of the laser working power and scan speed on the microstructural stability of oxide nanoparticles in the deposition layer was examined. Y-Ti-O type oxide nanoparticles with a mean diameter of 45 nm were successfully dispersed by the laser deposition process. The laser working power significantly affected nanoparticle size and number density. A high laser power with a low scan speed seriously induced particle coarsening and agglomeration. Compared with bulk oxide dispersion strengthened steel, the hardness of the laser deposition layer was much lower because of a relatively coarse particle and grain size. Formation mechanism of nanoparticles during laser deposition was discussed.

Cobalt nanoparticles encapsulated in nitrogen-rich carbon nanotubes as efficient catalysts for organic pollutants degradation via sulfite activation.

PubMed

Wu, Deming; Ye, Peng; Wang, Manye; Wei, Yi; Li, Xiaoxia; Xu, Aihua

2018-06-15

The activation of sulfite by heterogeneous catalysts displays a great potential in the development of new sulfate radials based technologies for wastewater treatment. Herein, cobalt nanoparticles embedded in N-doped carbon nanotubes (Co@NC) were prepared by a simple pyrolysis method. Due to the synergistic effects of the cobalt nanoparticles and N-doped carbon nanotubes, the Co@NC catalyst intrinsically shows an outstanding efficiency, excellent reusability and high stability in the catalytic oxidation of methyl orange (MO) in the presence of sulfite and dioxygen. The structure and efficiency of the catalyst was significantly affected by the content of cobalt and pyrolysis temperature. Several quenching experiments and electron paramagnetic resonance were carried out to investigate the catalytic mechanism. It is found that hydroxyl and sulfate radicals worked together to degrade MO in the system. The formation and decomposition of peroxymonosulfate may be an important route of these reactive radicals production. The effect of different anions, bicarbonate concentration, initial solution pH and dye types on the performance of the catalyst was also studied. This study can open a new approach for design and preparation of encapsulated cobalt in carbon materials as effective catalysts for pollutants degradation via sulfite activation. Copyright © 2018 Elsevier B.V. All rights reserved.

The strain and thermal induced tunable charging phenomenon in low power flexible memory arrays with a gold nanoparticle monolayer.

PubMed

Zhou, Ye; Han, Su-Ting; Xu, Zong-Xiang; Roy, V A L

2013-03-07

The strain and temperature dependent memory effect of organic memory transistors on plastic substrates has been investigated under ambient conditions. The gold (Au) nanoparticle monolayer was prepared and embedded in an atomic layer deposited aluminum oxide (Al(2)O(3)) as the charge trapping layer. The devices exhibited low operation voltage, reliable memory characteristics and long data retention time. Experimental analysis of the programming and erasing behavior at various bending states showed the relationship between strain and charging capacity. Thermal-induced effects on these memory devices have also been analyzed. The mobility shows ~200% rise and the memory window increases from 1.48 V to 1.8 V when the temperature rises from 20 °C to 80 °C due to thermally activated transport. The retention capability of the devices decreases with the increased working temperature. Our findings provide a better understanding of flexible organic memory transistors under various operating temperatures and validate their applications in various areas such as temperature sensors, temperature memory or advanced electronic circuits. Furthermore, the low temperature processing procedures of the key elements (Au nanoparticle monolayer and Al(2)O(3) dielectric layer) could be potentially integrated with large area flexible electronics.

Novel chitosan goethite bionanocomposite beads for arsenic remediation.

PubMed

He, Jing; Bardelli, Fabrizio; Gehin, Antoine; Silvester, Ewen; Charlet, Laurent

2016-09-15

We report on the synthesis and As adsorption properties of a novel chitosan - iron (oxyhydr)oxide composite material for the remediation of arsenic-contaminated water supplies. FE-SEM, Mössbauer spectroscopy, ICP-OES and synchrotron (Bulk XAS, μXRF) techniques were applied to determine the composition of the new material and investigate the As uptake efficiency and mechanism. The iron (oxyhydr)oxide phase has been identified as a nano-sized goethite, well dispersed in the chitosan matrix, leading to the name 'chitosan goethite bionanocomposite' (CGB). The CGB material is prepared in the form of beads of high density and excellent compression strength; the embedding of the goethite nanoparticles in the chitosan matrix allows for the high adsorption capacity of nanoparticles to be realized. CGB beads remove both As(III) and As(V) efficiently from water, over the pH range 5-9, negating the need for pre-oxidation of As(III). Kinetic studies and μXRF analysis of CGB bead sections show that diffusion-adsorption of As(V) into CGB beads is faster than for As(III). Using CGB beads, synthetic high-arsenic water (0.5 mg-As/L) could be purified to world drinking standard level (<0.01 mg-As/L) using only 1.4 g/L CGB. When considered in combination with the advantages of the low-cost of raw materials required, and facile (green) synthesis route, CGB is a promising material for arsenic remediation, particularly in developing countries, which suffer a diversity of socio-economical-traditional constraints for water purification and sanitation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Biosynthesis, characterization and antimicrobial activity of copper oxide nanoparticles (CONPs) produced using brown alga extract ( Bifurcaria bifurcata)

NASA Astrophysics Data System (ADS)

Abboud, Y.; Saffaj, T.; Chagraoui, A.; El Bouari, A.; Brouzi, K.; Tanane, O.; Ihssane, B.

2014-06-01

Recently, biosynthesis of nanoparticles has attracted scientists' attention because of the necessity to develop new clean, cost-effective and efficient synthesis techniques. In particular, metal oxide nanoparticles are receiving increasing attention in a large variety of applications. However, up to now, the reports on the biopreparation and characterization of nanocrystalline copper oxide are relatively few compared to some other metal oxides. In this paper, we report for the first time the use of brown alga ( Bifurcaria bifurcata) in the biosynthesis of copper oxide nanoparticles of dimensions 5-45 nm. The synthesized nanomaterial is characterized by UV-visible absorption spectroscopy and Fourier transform infrared spectrum analysis. X-ray diffraction confirms the formation and the crystalline nature of copper oxide nanomaterial. Further, these nanoparticles were found to exhibit high antibacterial activity against two different strains of bacteria Enterobacter aerogenes (Gram negative) and Staphylococcus aureus (Gram positive).

Magnetic/NIR-thermally responsive hybrid nanogels for optical temperature sensing, tumor cell imaging and triggered drug release

NASA Astrophysics Data System (ADS)

Wang, Hui; Yi, Jinhui; Mukherjee, Sumit; Banerjee, Probal; Zhou, Shuiqin

2014-10-01

The paper demonstrates a class of multifunctional core-shell hybrid nanogels with fluorescent and magnetic properties, which have been successfully developed for simultaneous optical temperature sensing, tumor cell imaging and magnetic/NIR-thermally responsive drug carriers. The as-synthesized hybrid nanogels were designed by coating bifunctional nanoparticles (BFNPs, fluorescent carbon dots embedded in the porous carbon shell and superparamagnetic iron oxide nanocrystals clustered in the core) with a thermo-responsive poly(N-isopropylacrylamide-co-acrylamide) [poly(NIPAM-AAm)]-based hydrogel as the shell. The BFNPs in hybrid nanogels not only demonstrate excellent photoluminescence (PL) and photostability due to the fluorescent carbon dots embedded in the porous carbon shell, but also has targeted drug accumulation potential and a magnetic-thermal conversion ability due to the superparamagnetic iron oxide nanocrystals clustered in the core. The thermo-responsive poly(NIPAM-AAm)-based gel shell can not only modify the physicochemical environment of the BFNPs core to manipulate the fluorescence intensity for sensing the variation of the environmental temperature, but also regulate the release rate of the loaded anticancer drug (curcumin) by varying the local temperature of environmental media. In addition, the carbon layer of BFNPs can adsorb and convert the NIR light to heat, leading to a promoted drug release under NIR irradiation and improving the therapeutic efficacy of drug-loaded hybrid nanogels. Furthermore, the superparamagnetic iron oxide nanocrystals in the core of BFNPs can trigger localized heating using an alternating magnetic field, leading to a phase change in the polymer gel to trigger the release of loaded drugs. Finally, the multifunctional hybrid nanogels can overcome cellular barriers to enter the intracellular region and light up the mouse melanoma B16F10 cells. The demonstrated hybrid nanogels would be an ideal system for the biomedical applications due to their excellent optical properties, magnetic properties, high drug loading capacity and responsive drug release behavior.The paper demonstrates a class of multifunctional core-shell hybrid nanogels with fluorescent and magnetic properties, which have been successfully developed for simultaneous optical temperature sensing, tumor cell imaging and magnetic/NIR-thermally responsive drug carriers. The as-synthesized hybrid nanogels were designed by coating bifunctional nanoparticles (BFNPs, fluorescent carbon dots embedded in the porous carbon shell and superparamagnetic iron oxide nanocrystals clustered in the core) with a thermo-responsive poly(N-isopropylacrylamide-co-acrylamide) [poly(NIPAM-AAm)]-based hydrogel as the shell. The BFNPs in hybrid nanogels not only demonstrate excellent photoluminescence (PL) and photostability due to the fluorescent carbon dots embedded in the porous carbon shell, but also has targeted drug accumulation potential and a magnetic-thermal conversion ability due to the superparamagnetic iron oxide nanocrystals clustered in the core. The thermo-responsive poly(NIPAM-AAm)-based gel shell can not only modify the physicochemical environment of the BFNPs core to manipulate the fluorescence intensity for sensing the variation of the environmental temperature, but also regulate the release rate of the loaded anticancer drug (curcumin) by varying the local temperature of environmental media. In addition, the carbon layer of BFNPs can adsorb and convert the NIR light to heat, leading to a promoted drug release under NIR irradiation and improving the therapeutic efficacy of drug-loaded hybrid nanogels. Furthermore, the superparamagnetic iron oxide nanocrystals in the core of BFNPs can trigger localized heating using an alternating magnetic field, leading to a phase change in the polymer gel to trigger the release of loaded drugs. Finally, the multifunctional hybrid nanogels can overcome cellular barriers to enter the intracellular region and light up the mouse melanoma B16F10 cells. The demonstrated hybrid nanogels would be an ideal system for the biomedical applications due to their excellent optical properties, magnetic properties, high drug loading capacity and responsive drug release behavior. Electronic supplementary information (ESI) available: Fig. S1-S12. See DOI: 10.1039/c4nr03748k

Viscosity, density, and thermal conductivity of aluminum oxide and zinc oxide nanolubricants

PubMed Central

Kedzierski, M.A.; Brignoli, R.; Quine, K.T.; Brown, J.S.

2017-01-01

This paper presents liquid kinematic viscosity, density, and thermal conductivity measurements of eleven different synthetic polyolester-based nanoparticle nanolubricants (dispersions) at atmospheric pressure over the temperature range 288 K to 318 K. Aluminum oxide (Al2O3) and zinc oxide (ZnO) nanoparticles with nominal diameters of 127 nm and 135 nm, respectively, were investigated. A good dispersion of the spherical and non-spherical nanoparticles in the lubricant was maintained with a surfactant. Viscosity, density, and thermal conductivity measurements were made for the neat lubricant along with eleven nanolubricants with differing nanoparticle and surfactant mass fractions. Existing models were used to predict kinematic viscosity (±20%), thermal conductivity (±1%), and specific volume (±6%) of the nanolubricant as a function of temperature, nanoparticle mass fraction, surfactant mass fraction, and nanoparticle diameter. The liquid viscosity, density and thermal conductivity were shown to increase with respect to increasing nanoparticle mass fraction. PMID:28736463

Synthesis and morphology of hydroxyapatite/polyethylene oxide nanocomposites with block copolymer compatibilized interfaces

NASA Astrophysics Data System (ADS)

Lee, Ji Hoon; Shofner, Meisha

2012-02-01

In order to exploit the promise of polymer nanocomposites, special consideration should be given to component interfaces during synthesis and processing. Previous results from this group have shown that nanoparticles clustered into larger structures consistent with their native shape when the polymer matrix crystallinity was high. Therefore in this research, the nanoparticles are disguised from a highly-crystalline polymer matrix by cloaking them with a matrix-compatible block copolymer. Specifically, spherical and needle-shaped hydroxyapatite nanoparticles were synthesized using a block copolymer templating method. The block copolymer used, polyethylene oxide-b-polymethacrylic acid, remained on the nanoparticle surface following synthesis with the polyethylene oxide block exposed. These nanoparticles were subsequently added to a polyethylene oxide matrix using solution processing. Characterization of the nanocomposites indicated that the copolymer coating prevented the nanoparticles from assembling into ordered clusters and that the matrix crystallinity was decreased at a nanoparticle spacing of approximately 100 nm.

Bacterial toxicity comparison between nano- and micro-scaled oxide particles.

PubMed

Jiang, Wei; Mashayekhi, Hamid; Xing, Baoshan

2009-05-01

Toxicity of nano-scaled aluminum, silicon, titanium and zinc oxides to bacteria (Bacillus subtilis, Escherichia coli and Pseudomonas fluorescens) was examined and compared to that of their respective bulk (micro-scaled) counterparts. All nanoparticles but titanium oxide showed higher toxicity (at 20 mg/L) than their bulk counterparts. Toxicity of released metal ions was differentiated from that of the oxide particles. ZnO was the most toxic among the three nanoparticles, causing 100% mortality to the three tested bacteria. Al(2)O(3) nanoparticles had a mortality rate of 57% to B. subtilis, 36% to E. coli, and 70% to P. fluorescens. SiO(2) nanoparticles killed 40% of B. subtilis, 58% of E. coli, and 70% of P. fluorescens. TEM images showed attachment of nanoparticles to the bacteria, suggesting that the toxicity was affected by bacterial attachment. Bacterial responses to nanoparticles were different from their bulk counterparts; hence nanoparticle toxicity mechanisms need to be studied thoroughly.

Laser-induced growth of nanocrystals embedded in porous materials

PubMed Central

2013-01-01

Space localization of the linear and nonlinear optical properties in a transparent medium at the submicron scale is still a challenge to yield the future generation of photonic devices. Laser irradiation techniques have always been thought to structure the matter at the nanometer scale, but combining them with doping methods made it possible to generate local growth of several types of nanocrystals in different kinds of silicate matrices. This paper summarizes the most recent works developed in our group, where the investigated nanoparticles are either made of metal (gold) or chalcogenide semiconductors (CdS, PbS), grown in precursor-impregnated porous xerogels under different laser irradiations. This review is associated to new results on silver nanocrystals in the same kind of matrices. It is shown that, depending on the employed laser, the particles can be formed near the sample surface or deep inside the silica matrix. Photothermal and/or photochemical mechanisms may be invoked to explain the nanoparticle growth, depending on the laser, precursor, and matrix. One striking result is that metal salt reduction, necessary to the production of the corresponding nanoparticles, can efficiently occur due to the thermal wrenching of electrons from the matrix itself or due to multiphoton absorption of the laser light by a reducer additive in femtosecond regime. Very localized semiconductor quantum dots could also be generated using ultrashort pulses, but while PbS nanoparticles grow faster than CdS particles due to one-photon absorption, this better efficiency is counterbalanced by a sensitivity to oxidation. In most cases where the reaction efficiency is high, particles larger than the pores have been obtained, showing that a fast diffusion of the species through the interconnected porosity can modify the matrix itself. Based on our experience in these techniques, we compare several examples of laser-induced nanocrystal growth in porous silica xerogels, which allows extracting the best experimental conditions to obtain an efficient particle production and to avoid stability or oxidation problems. PMID:23742134

The discovery of silicon oxide nanoparticles in space-weathered of Apollo 15 lunar soil grains

NASA Astrophysics Data System (ADS)

Gu, Lixin; Zhang, Bin; Hu, Sen; Noguchi, Takaaki; Hidaka, Hiroshi; Lin, Yangting

2018-03-01

Space weathering is an important process on the Moon and other airless celestial bodies. The most common space weathering effects are amorphization of the top surface of soil grains and formation of nanophase iron particles (npFe) within the partially amorphous rims. Hence, space weathering significantly affects optical properties of the surface of the Moon and other airless celestial bodies. Transmission electron microscope (TEM) analysis of Apollo 15 soil grains displays npFe (≤5 nm in size) embedded in the space-weathered rim (∼60 nm in thickness) of a pyroxene grain, consistent with previous studies. In contrast, submicron-sized fragments that adhere to the pyroxene grain show distinct space weathering features. Silicon oxide nanoparticles (npSiOx) were observed with npFe in a submicron-sized Mg-Fe silicate fragment. This is the first discovery of npSiOx as a product of space weathering. The npSiOx and the coexisting npFe are ∼10-25 nm in size, significantly larger than the typical npFe in the space weathered rim of the pyroxene grain. The coexisting npSiOx and npFe were probably formed directly in micrometeorite shock-induced melt, instead of in a solar-wind generated vapor deposit or irradiated rim. This new observation will shed light on space weathering processes on the Moon and airless celestial bodies.

Preparation and characterization of mesoporous TiO2-sphere-supported Au-nanoparticle catalysts with high activity for CO oxidation at ambient temperature

NASA Astrophysics Data System (ADS)

Wang, Lili; Huang, Shouying; Zhu, Baolin; Zhang, Shoumin; Huang, Weiping

2016-11-01

Mesoporous TiO2-sphere-supported Au-nanoparticles (Au/m-TiO2-spheres) catalysts have been synthesized by a simple method using tetrabutyl titanate as TiO2 precursor and characterized with XRD, BET, ICP, SEM, TEM, UV-Vis DRS, XPS, as well as FT-IR. The samples with the size in the range of 200-400 nm were almost perfectly spherical. The average diameter of pores was about 3.6 nm, and the mesopore size distribution was in the range of 2-6 nm with a narrow distribution. When the catalyst was calcined at 300 °C, the Au NPs with the size ca. 5 nm were highly dispersed on the surfaces of m-TiO2 spheres and partially embedded in the supports. Remarkably, the specific surface area of the Au/m-TiO2-spheres was as high as 117 m2 g-1. The CO-adsorbed catalyst showed an apparent IR adsorption peak at 1714 cm-1 that matched with bridging model CO. It means the catalysts should be of high catalytic activity for the CO oxidation due to they could adsorb and activate CO commendably. When Au-content was 0.48 wt.%, the Au/m-TiO2-spheres could convert CO completely into CO2 at ambient temperature.

Selective laser melting porous metallic implants with immobilized silver nanoparticles kill and prevent biofilm formation by methicillin-resistant Staphylococcus aureus.

PubMed

van Hengel, Ingmar A J; Riool, Martijn; Fratila-Apachitei, Lidy E; Witte-Bouma, Janneke; Farrell, Eric; Zadpoor, Amir A; Zaat, Sebastian A J; Apachitei, Iulian

2017-09-01

Implant-associated infection and limited longevity are two major challenges that orthopedic devices need to simultaneously address. Additively manufactured porous implants have recently shown tremendous promise in improving bone regeneration and osseointegration, but, as any conventional implant, are threatened by infection. In this study, we therefore used rational design and additive manufacturing in the form of selective laser melting (SLM) to fabricate porous titanium implants with interconnected pores, resulting in a 3.75 times larger surface area than corresponding solid implants. The SLM implants were biofunctionalized by embedding silver nanoparticles in an oxide surface layer grown using plasma electrolytic oxidation (PEO) in Ca/P-based electrolytes. The PEO layer of the SLM implants released silver ions for at least 28 days. X-ray diffraction analysis detected hydroxyapatite on the SLM PEO implants but not on the corresponding solid implants. In vitro and ex vivo assays showed strong antimicrobial activity of these novel SLM PEO silver-releasing implants, without any signs of cytotoxicity. The rationally designed SLM porous implants outperformed solid implants with similar dimensions undergoing the same biofunctionalization treatment. This included four times larger amount of released silver ions, two times larger zone of inhibition, and one additional order of magnitude of reduction in numbers of CFU in an ex vivo mouse infection model. Copyright © 2017 Elsevier Ltd. All rights reserved.

Calibrating the imaging and therapy performance of magneto-fluorescent gold nanoshells for breast cancer

NASA Astrophysics Data System (ADS)

Dowell, Adam; Chen, Wenxue; Biswal, Nrusingh; Ayala-Orozco, Ciceron; Giuliano, Mario; Schiff, Rachel; Halas, Naomi J.; Joshi, Amit

2012-03-01

Gold nanoshells with NIR plasmon resonance can be modified to simultaneously enhance conjugated NIR fluorescence dyes and T2 contrast of embedded iron-oxide nanoparticles, and molecularly targeted to breast and other cancers. We calibrated the theranostic performance of magneto-fluorescent nanoshells, and contrasted the performance of molecularly targeted and untargeted nanoshells for breast cancer therapy, employing MCF-7L and their HER2 overexpressing derivative MCF-7/HER2-18 breast cancer cells as in vitro model systems. Silica core gold nanoshells with plasmon resonance on ~810 nm were doped with NIR dye ICG and ~10 nm iron-oxide nanoparticles in a ~20 nm epilayer of silica. A subset of nanoshells was conjugated to antibodies targeting HER2. Cell viability with varying laser power levels in presence and absence of bare and HER2-targeted nanoshells was assessed by calcein and propidium iodide staining. For MCF-7L cells, increasing power resulted in increased cell death (F=5.63, p=0.0018), and bare nanoshells caused more cell death than HER2-targeted nanoshells or laser treatment alone (F=30.13, p<0.001). For MCF-7/HER2-18 cells, death was greater with HER2-targeted nanoshells and was independent of laser power. This study demonstrates the capability of magneto-fluorescent nanocomplexes for imaging and therapy of breast cancer cells, and the advantages of targeting receptors unique to cancer cells.

Preparation, characterization and dynamical mechanical properties of dextran-coated iron oxide nanoparticles (DIONPs).

PubMed

Can, Hatice Kaplan; Kavlak, Serap; ParviziKhosroshahi, Shahed; Güner, Ali

2018-03-01

Dextran-coated iron oxide nanoparticles (DIONPs) with appropriate surface chemistry exhibit many interesting properties that can be exploited in a variety of biomedical applications such as magnetic resonance imaging (MRI) contrast enhancement, tissue repair, hyperthermia, drug delivery and in cell separation. This paper reports the experimental detail for preparation, characterization and investigation of thermal and dynamical mechanical characteristics of the dextran-coated Fe 3 O 4 magnetic nanoparticles. In our work, DIONPs were prepared in a 1:2 ratio of Fe(II) and Fe(III) salt in the HCl solution with NaOH at given temperature. The obtained dextran-coated iron-oxide nanoparticles structure-property correlation was characterized by spectroscopic methods; attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and XRD. Coating dextran on the iron-oxide proof of important peaks can be seen from the ATR-FTIR. Dramatic crystallinity increment can be observed from the XRD pattern of the iron-oxide dextran nanoparticles. The thermal analysis was examined by differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA) and differential thermal analysis (DTA). Dynamical mechanical properties of dextran nanoparticles were analysed by dynamic mechanical analysis (DMA). Thermal stability of the iron oxide dextran nanoparticles is higher than that of the dextran.

Implications of room temperature oxidation on crystal structure and exchange bias effect in Co/CoO nanoparticles

DOE PAGES

Feygenson, Mikhail; Formo, Eric V.; Freeman, Katherine; ...

2015-11-02

In this study, we describe how the exchange bias effect in Co/CoO nanoparticles depends on the size focusing and temperature treatment of precursor Co nanoparticles before oxidation at ambient conditions. By appealing to magnetization, microscopy, neutron and synchrotron x-ray measurements we found that as-synthesized Co nanoparticles readily oxidize in air only after 20 days. The highest exchange bias field of 814 Oe is observed at T = 2K. When the same nanoparticles are centrifuged and annealed at 70 °C in vacuum prior to oxidation, the exchange bias field is increased to 2570 Oe. Annealing of Co nanoparticles in vacuum improvesmore » their crystallinity and prevents complete oxidation, so that Co-core/CoO-shell structure is preserved even after 120 days. The crystal structure of CoO shell in both samples is different from its bulk counterpart. Implications of such distorted CoO shells on exchange bias are discussed. Coating of Co nanoparticles with amorphous silica shell makes them resistant to oxidation, but ultimately modifies the crystal structure of both Co core and SiO 2 shell.« less

First Principles Study on the CO Oxidation on Mn-Embedded Divacancy Graphene

PubMed Central

Jiang, Quanguo; Zhang, Jianfeng; Ao, Zhimin; Huang, Huajie; He, Haiyan; Wu, Yuping

2018-01-01

The CO oxidation mechanism on graphene with divacancy (DG) embedded with transition metal from Sc to Zn has been studied by using first principles calculations. The results indicate that O2 molecule is preferentially adsorbed on Sc, Ti, V, Cr, Mn, and Fe-DG, which can avoid the CO poisoning problem that many catalysts facing and is beneficial to the CO oxidation progress. Further study indicates that Mn-DG shows the best catalytic properties for CO oxidation with consideration of both Langmuir-Hinshelwood (LH) and Eley-Rideal (ER) oxidation mechanisms. Along the ER mechanism, the reaction energy barrier for the first step (CO free + O2 pre-adsorbed → OOCO) is 0.96 eV. Along the LH mechanism, the energy barrier for the rate limiting step (CO adsorbed + O2 adsorbed → OOCO) is only 0.41 eV, indicating that the CO oxidation on Mn-DG will occur along LH mechanism. The Hirshfeld charge distributions of O2 and CO molecules is tuned by the embedded Mn atom, and the charge transfer from the embedded Mn atom to the adsorbed molecules plays an important role for the CO oxidation. The result shows that the Mn-embedded divacancy graphene is a noble-metal free and efficient catalyst for CO oxidation at low temperature.

Facile solid-state synthesis of oxidation-resistant metal nanoparticles at ambient conditions

NASA Astrophysics Data System (ADS)

Lee, Kyu Hyung; Jung, Hyuk Joon; Lee, Ju Hee; Kim, Kyungtae; Lee, Byeongno; Nam, Dohyun; Kim, Chung Man; Jung, Myung-Hwa; Hur, Nam Hwi

2018-05-01

A simple and scalable method for the synthesis of metal nanoparticles in the solid-state was developed, which can produce nanoparticles in the absence of solvents. Nanoparticles of coinage metals were synthesized by grinding solid hydrazine and the metal precursors in their acetates and oxides at 25 °C. The silver and gold acetates converted completely within 6 min into Ag and Au nanoparticles, respectively, while complete conversion of the copper acetate to the Cu sub-micrometer particles took about 2 h. Metal oxide precursors were also converted into metal nanoparticles by grinding alone. The resulting particles exhibit distinctive crystalline lattice fringes, indicating the formation of highly crystalline phases. The Cu sub-micrometer particles are better resistant to oxidation and exhibit higher conductivity compared to conventional Cu nanoparticles. This solid-state method was also applied for the synthesis of platinum group metals and intermetallic Cu3Au, which can be further extended to synthesize other metal nanoparticles.

Titanium-doped cerium oxide nanoparticles protect cells from hydrogen peroxide-induced apoptosis

NASA Astrophysics Data System (ADS)

Clark, Andrea; Zhu, Aiping; Petty, Howard R.

2013-12-01

To develop new nanoparticle materials possessing antioxidative capacity with improved physical characteristics, we have studied titanium-doped cerium oxide (CeTiO2) nanoparticles. CeTiO2 nanoparticles had mode diameters in the range of 15-20 nm. These nanoparticles demonstrated catalase activity, and did not promote the activation of hemolytic or cytolytic pathways in living cells. Using surface plasmon resonance-enhanced microscopy, we find that these nanoparticles associate with cells. Transmission electron microscopy studies demonstrated that these nanoparticles accumulate within the vacuolar compartment of cells. Importantly, CeTiO2 nanoparticles decrease hydrogen peroxide-mediated apoptosis of cells as judged by the reduced cleavage of a caspase 3-sensitive label. CeTiO2 nanoparticles may contribute to deflecting tissue damage in a broad spectrum of oxidant-mediated diseases, such as macular degeneration and Alzheimer's disease.

Fabrication of high flux and antifouling mixed matrix fumarate-alumoxane/PAN membranes via electrospinning for application in membrane bioreactors

NASA Astrophysics Data System (ADS)

Moradi, Golshan; Zinadini, Sirus; Rajabi, Laleh; Dadari, Soheil

2018-01-01

The nanofibrous Polyacrylonitrile (PAN) membranes embedded with fumarate-alumoxane (Fum-A) nanoparticles were prepared via electrospinning technique as high flux and antifouling membranes for membrane bioreactor (MBR) applications. The effect of Fum-A nanoparticles on membrane morphology, surface hydrophilicity, pure water flux, effluent turbidity and the antifouling property was investigated. Fum-A is a carboxylate-alumoxane nanoparticle covered by extra hydroxyl and carboxylate groups on its surface. By embedding Fum-A nanoparticles into the spinning solution, the surface hydrophilicity and pure water flux of the resulted membranes were improved. The smooth surface of fibers at the low amount of nanoparticles and the agglomeration of nanoparticles at their high concentration were shown in SEM images of the membranes surface. The energy dispersive spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR) analysis of the prepared Fum-A/PAN membrane confirmed the presence of carboxylate and hydroxyl functional groups of Fum-A nanoparticles on the surface of the Fum-A nanoparticles containing membrane. The results obtained from the filtration of activated sludge suspension revealed that by addition of a low amount of Fum-A nanoparticles, the irreversible fouling was significantly decreased due to the higher hydrophilicity. The Fum-A/PAN membranes showed superior permeate flux and antifouling properties compared to bare electrospun PAN membrane. Finally, 2 wt.% Fum-A/PAN membrane exhibited the highest FRR of 96% and the lowest irreversible fouling of 4% with excellent durability of antifouling property during twenty repeated activated sludge filtrations.

Gas Sensors Based on Tin Oxide Nanoparticles Synthesized from a Mini-Arc Plasma Source

DOE PAGES

Lu, Ganhua; Huebner, Kyle L.; Ocola, Leonidas E.; ...

2006-01-01

Minimore » aturized gas sensors or electronic noses to rapidly detect and differentiate trace amount of chemical agents are extremely attractive. In this paper, we report on the fabrication and characterization of a functional tin oxide nanoparticle gas sensor. Tin oxide nanoparticles are first synthesized using a convenient and low-cost mini-arc plasma source. The nanoparticle size distribution is measured online using a scanning electrical mobility spectrometer (SEMS). The product nanoparticles are analyzed ex-situ by high resolution transmission electron microscopy (HRTEM) for morphology and defects, energy dispersive X-ray (EDX) spectroscopy for elemental composition, electron diffraction for crystal structure, and X-ray photoelectron spectroscopy (XPS) for surface composition. Nonagglomerated rutile tin oxide ( SnO 2 ) nanoparticles as small as a few nm have been produced. Larger particles bear a core-shell structure with a metallic core and an oxide shell. The nanoparticles are then assembled onto an e-beam lithographically patterned interdigitated electrode using electrostatic force to fabricate the gas sensor. The nanoparticle sensor exhibits a fast response and a good sensitivity when exposed to 100 ppm ethanol vapor in air.« less

Synthesis of oxide-free aluminum nanoparticles for application to conductive film

NASA Astrophysics Data System (ADS)

Jong Lee, Yung; Lee, Changsoo; Lee, Hyuck Mo

2018-02-01

Aluminum nanoparticles are considered promising as alternatives to conventional ink materials, replacing silver and copper nanoparticles, due to their extremely low cost and low melting temperature. However, a serious obstacle to realizing their use as conductive ink materials is the oxidation of aluminum. In this research, we synthesized the oxide-free aluminum nanoparticles using catalytic decomposition and an oleic acid coating method, and these materials were applied to conductive ink for the first time. The injection time of oleic acid determines the size of the aluminum nanoparticles by forming a self-assembled monolayer on the nanoparticles instead of allowing the formation of an oxide phase. Fabricated nanoparticles were analyzed by transmission electron microscopy and x-ray photoelectron spectroscopy to verify their structural and chemical composition. In addition, conductive inks made of these nanoparticles exhibit electrical properties when they are sintered at over 300 °C in a reducing atmosphere. This result shows that aluminum nanoparticles can be used as an alternative conductive material in printed electronics and can solve the cost issues associated with noble metals.

Surface functionalization of dopamine coated iron oxide nanoparticles for various surface functionalities

NASA Astrophysics Data System (ADS)

Sherwood, Jennifer; Xu, Yaolin; Lovas, Kira; Qin, Ying; Bao, Yuping

2017-04-01

We present effective conjugation of four small molecules (glutathione, cysteine, lysine, and Tris(hydroxymethyl)aminomethane) onto dopamine-coated iron oxide nanoparticles. Conjugation of these molecules could improve the surface functionality of nanoparticles for more neutral surface charge at physiological pH and potentially reduce non-specific adsorption of proteins to nanoparticles surfaces. The success of conjugation was evaluated with dynamic light scattering by measuring the surface charge changes and Fourier transform infrared spectroscopy for surface chemistry analysis. The stability of dopamine-coated nanoparticles and the ability of conjugated nanoparticles to reduce the formation of protein corona were evaluated by measuring the size and charge of the nanoparticles in biological medium. This facile conjugation method opens up possibilities for attaching various surface functionalities onto iron oxide nanoparticle surfaces for biomedical applications.

Antimicrobial properties and mechanism of magnesium oxide nanoparticles on Campylobacter, E. coli O157:H7, and Salmonella

USDA-ARS?s Scientific Manuscript database

Background: Metal oxide nanoparticles have considerable potential as antimicrobial agents in food safety applications due to their structure, surface properties, and stability. In this study, the antibacterial effects and mechanisms of Magnesium Oxide Nanoparticles (MgO NPs, with an average size o...

Ultrasound irradiation based in-situ synthesis of star-like Tragacanth gum/zinc oxide nanoparticles on cotton fabric.

PubMed

Ghayempour, Soraya; Montazer, Majid

2017-01-01

Application of natural biopolymers for green and safe synthesis of zinc oxide nanoparticles on the textiles is a novel and interesting approach. The present study offers the use of natural biopolymer, Tragacanth gum, as the reducing, stabilizing and binding agent for in-situ synthesis of zinc oxide nanoparticles on the cotton fabric. Ultrasonic irradiation leads to clean and easy synthesis of zinc oxide nanoparticles in short-time at low-temperature. FESEM/EDX, XRD, FT-IR spectroscopy, DSC, photocatalytic activities and antimicrobial assay are used to characterize Tragacanth gum/zinc oxide nanoparticles coated cotton fabric. The analysis confirmed synthesis of star-like zinc oxide nanoparticles with hexagonal wurtzite structure on the cotton fabric with the average particle size of 62nm. The finished cotton fabric showed a good photocatalytic activity on degradation of methylene blue and 100% antimicrobial properties with inhibition zone of 3.3±0.1, 3.1±0.1 and 3.0±0.1mm against Staphylococcus aureus, Escherichia coli and Candida albicans. Copyright © 2016 Elsevier B.V. All rights reserved.

Adsorption of collagen to indium oxide nanoparticles and infrared emissivity study thereon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou Yuming; Shan Yun; Sun Yanqing

Adsorption of collagen to indium oxide nanoparticles was carried out in water-acetone solution at volumetric ratio of 1:1 with pH value varying from 3.2 to 9.3. As indicated by TGA, maximum collagen adsorption to indium oxide nanoparticles occurred at pH of 3.2. It was proposed that noncovalent interactions such as hydrogen bonding, hydrophilic and electrostatic interactions made main contributions to collagen adsorption. The IR emissivity values (8-14 {mu}m) of collagen-adsorbed indium oxide nanoparticles decreased significantly compared to either pure collagen or indium oxide nanoparticles possibly due to the interfacial interactions between collagen and indium oxide nanoparticles. And the lowest infraredmore » emissivity value of 0.587 was obtained at collagen adsorption of 1.94 g/100 g In{sub 2}O{sub 3}. On the chance of improved compatibility with organic adhesives, the chemical activity of adsorbed collagen was further confirmed by grafting copolymerization with methyl methacrylate by formation of polymer shell outside, as evidenced by IR spectrum and transmission electron microscopy.« less

Theoretical Design and Experimental Realization of Quasi Single Electron Enhancement in Plasmonic Catalysis.

PubMed

Wang, Jiale; Alves, Tiago V; Trindade, Fabiane J; de Aquino, Caroline B; Pieretti, Joana C; Domingues, Sergio H; Ando, Romulo A; Ornellas, Fernando R; Camargo, Pedro H C

2015-11-23

By a combination of theoretical and experimental design, we probed the effect of a quasi-single electron on the surface plasmon resonance (SPR)-mediated catalytic activities of Ag nanoparticles. Specifically, we started by theoretically investigating how the E-field distribution around the surface of a Ag nanosphere was influenced by static electric field induced by one, two, or three extra fixed electrons embedded in graphene oxide (GO) next to the Ag nanosphere. We found that the presence of the extra electron(s) changed the E-field distributions and led to higher electric field intensities. Then, we experimentally observed that a quasi-single electron trapped at the interface between GO and Ag NPs in Ag NPs supported on graphene oxide (GO-Ag NPs) led to higher catalytic activities as compared to Ag and GO-Ag NPs without electrons trapped at the interface, representing the first observation of catalytic enhancement promoted by a quasi-single electron. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Surface and interfacial engineering of iron oxide nanoplates for highly efficient magnetic resonance angiography.

PubMed

Zhou, Zijian; Wu, Changqiang; Liu, Hanyu; Zhu, Xianglong; Zhao, Zhenghuan; Wang, Lirong; Xu, Ye; Ai, Hua; Gao, Jinhao

2015-03-24

Magnetic resonance angiography using gadolinium-based molecular contrast agents suffers from short diagnostic window, relatively low resolution and risk of toxicity. Taking into account the chemical exchange between metal centers and surrounding protons, magnetic nanoparticles with suitable surface and interfacial features may serve as alternative T1 contrast agents. Herein, we report the engineering on surface structure of iron oxide nanoplates to boost T1 contrast ability through synergistic effects between exposed metal-rich Fe3O4(100) facets and embedded Gd2O3 clusters. The nanoplates show prominent T1 contrast in a wide range of magnetic fields with an ultrahigh r1 value up to 61.5 mM(-1) s(-1). Moreover, engineering on nanobio interface through zwitterionic molecules adjusts the in vivo behaviors of nanoplates for highly efficient magnetic resonance angiography with steady-state acquisition window, superhigh resolution in vascular details, and low toxicity. This study provides a powerful tool for sophisticated design of MRI contrast agents for diverse use in bioimaging applications.

Subsurface synthesis and characterization of Ag nanoparticles embedded in MgO

NASA Astrophysics Data System (ADS)

Vilayurganapathy, S.; Devaraj, A.; Colby, R.; Pandey, A.; Varga, T.; Shutthanandan, V.; Manandhar, S.; El-Khoury, P. Z.; Kayani, Asghar; Hess, W. P.; Thevuthasan, S.

2013-03-01

Metal nanoparticles exhibit a localized surface plasmon resonance (LSPR) which is very sensitive to the size and shape of the nanoparticle and the surrounding dielectric medium. The coupling between the electromagnetic radiation and the localized surface plasmon in metallic nanoparticles results in a sizable enhancement of the incident fields, making them possible candidates for plasmonic applications. In particular, partially exposed metallic nanoparticles distributed in a dielectric matrix can provide prime locations for LSPR spectroscopy and sensing. We report the synthesis and characterization of a plasmonic substrate consisting of Ag nanoparticles partially buried in MgO. Ag nanoparticles of different shapes and size distributions were synthesized below the surface of MgO by implanting 200 keV Ag+ ions followed by annealing at 1000 °C for 10 and 30 h. A detailed optical and structural characterization was carried out to understand the evolution of the Ag nanoparticle and size distribution inside the MgO matrix. Micro x-ray diffraction (Micro-XRD) was employed to investigate the structural properties and estimate the crystallite size. The nanoparticles evolved from a spherical to a faceted morphology with annealing time, assuming an octahedral shape truncated at the (001) planes, as visualized from aberration-corrected transmission electron microscopy (TEM) images. The nanoparticles embedded in MgO were shown to be pure metallic Ag using atom probe tomography (APT). The nanoparticles were partially exposed to the surface by employing plasma etch techniques to remove the overlaying MgO. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were employed to study the surface morphology and obtain a height distribution for the partially exposed nanoparticles.

Synthesis and Stabilization of Supported Metal Catalysts by Atomic Layer Deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu, Junling; Elam, Jeffrey W.; Stair, Peter C.

2013-03-12

Supported metal nanoparticles are among the most important cata-lysts for many practical reactions, including petroleum refining, automobile exhaust treatment, and Fischer–Tropsch synthesis. The catalytic performance strongly depends on the size, composition, and structure of the metal nanoparticles, as well as the underlying support. Scientists have used conventional synthesis methods including impregnation, ion exchange, and deposition–precipitation to control and tune these factors, to establish structure–performance relationships, and to develop better catalysts. Meanwhile, chemists have improved the stability of metal nanoparticles against sintering by the application of protective layers, such as polymers and oxides that encapsulate the metal particle. This often leadsmore » to decreased catalytic activity due to a lack of precise control over the thickness of the protective layer. A promising method of catalyst synthesis is atomic layer deposition (ALD). ALD is a variation on chemical vapor deposition in which metals, oxides, and other materials are deposited on surfaces by a sequence of self-limiting reactions. The self-limiting character of these reactions makes it possible to achieve uniform deposits on high-surface-area porous solids. Therefore, design and synthesis of advanced catalysts on the nanoscale becomes possible through precise control over the structure and composition of the underlying support, the catalytic active sites, and the protective layer. In this Account, we describe our advances in the synthesis and stabilization of supported metal catalysts by ALD. After a short introduction to the technique of ALD, we show several strategies for metal catalyst synthesis by ALD that take advantage of its self-limiting feature. Monometallic and bimetallic catalysts with precise control over the metal particle size, composition, and structure were achieved by combining ALD sequences, surface treatments, and deposition temperature control. Next, we describe ALD oxide overcoats applied with atomically precise thickness control that stabilize metal catalysts while preserving their catalytic function. We also discuss strategies for generation and control over the porosity of the overcoats that allow the embedded metal particles to remain accessible by reactants, and the details for ALD alumina overcoats on metal catalysts. Moreover, using methanol decomposition and oxidative dehydrogenation of ethane as probe reactions, we demonstrate that selectively blocking low coordination metal sites by oxide overcoats can provide another strategy to enhance both the durability and selectivity of metal catalysts.« less

Suppressing iron oxide nanoparticle toxicity by vascular targeted antioxidant polymer nanoparticles.

PubMed

Cochran, David B; Wattamwar, Paritosh P; Wydra, Robert; Hilt, J Zach; Anderson, Kimberly W; Eitel, Richard E; Dziubla, Thomas D

2013-12-01

The biomedical use of superparamagnetic iron oxide nanoparticles has been of continued interest in the literature and clinic. Their ability to be used as contrast agents for imaging and/or responsive agents for remote actuation makes them exciting materials for a wide range of clinical applications. Recently, however, concern has arisen regarding the potential health effects of these particles. Iron oxide toxicity has been demonstrated in in vivo and in vitro models, with oxidative stress being implicated as playing a key role in this pathology. One of the key cell types implicated in this injury is the vascular endothelial cells. Here, we report on the development of a targeted polymeric antioxidant, poly(trolox ester), nanoparticle that can suppress oxidative damage. As the polymer undergoes enzymatic hydrolysis, active trolox is locally released, providing a long term protection against pro-oxidant agents. In this work, poly(trolox) nanoparticles are targeted to platelet endothelial cell adhesion molecules (PECAM-1), which are able to bind to and internalize in endothelial cells and provide localized protection against the cytotoxicity caused by iron oxide nanoparticles. These results indicate the potential of using poly(trolox ester) as a means of mitigating iron oxide toxicity, potentially expanding the clinical use and relevance of these exciting systems. Copyright © 2013 Elsevier Ltd. All rights reserved.

High-performance iron oxide nanoparticles for magnetic particle imaging - guided hyperthermia (hMPI)

NASA Astrophysics Data System (ADS)

Bauer, Lisa M.; Situ, Shu F.; Griswold, Mark A.; Samia, Anna Cristina S.

2016-06-01

Magnetic particle imaging (MPI) is an emerging imaging modality that allows the direct and quantitative mapping of iron oxide nanoparticles. In MPI, the development of tailored iron oxide nanoparticle tracers is paramount to achieving high sensitivity and good spatial resolution. To date, most MPI tracers being developed for potential clinical applications are based on spherical undoped magnetite nanoparticles. For the first time, we report on the systematic investigation of the effects of changes in chemical composition and shape anisotropy on the MPI performance of iron oxide nanoparticle tracers. We observed a 2-fold enhancement in MPI signal through selective doping of magnetite nanoparticles with zinc. Moreover, we demonstrated focused magnetic hyperthermia heating by adapting the field gradient used in MPI. By saturating the iron oxide nanoparticles outside of a field free region (FFR) with an external static field, we can selectively heat a target region in our test sample. By comparing zinc-doped magnetite cubic nanoparticles with undoped spherical nanoparticles, we could show a 5-fold improvement in the specific absorption rate (SAR) in magnetic hyperthermia while providing good MPI signal, thereby demonstrating the potential for high-performance focused hyperthermia therapy through an MPI-guided approach (hMPI).Magnetic particle imaging (MPI) is an emerging imaging modality that allows the direct and quantitative mapping of iron oxide nanoparticles. In MPI, the development of tailored iron oxide nanoparticle tracers is paramount to achieving high sensitivity and good spatial resolution. To date, most MPI tracers being developed for potential clinical applications are based on spherical undoped magnetite nanoparticles. For the first time, we report on the systematic investigation of the effects of changes in chemical composition and shape anisotropy on the MPI performance of iron oxide nanoparticle tracers. We observed a 2-fold enhancement in MPI signal through selective doping of magnetite nanoparticles with zinc. Moreover, we demonstrated focused magnetic hyperthermia heating by adapting the field gradient used in MPI. By saturating the iron oxide nanoparticles outside of a field free region (FFR) with an external static field, we can selectively heat a target region in our test sample. By comparing zinc-doped magnetite cubic nanoparticles with undoped spherical nanoparticles, we could show a 5-fold improvement in the specific absorption rate (SAR) in magnetic hyperthermia while providing good MPI signal, thereby demonstrating the potential for high-performance focused hyperthermia therapy through an MPI-guided approach (hMPI). Electronic supplementary information (ESI) available: Detailed IONP synthetic methods, description of magnetic particle relaxometer set-up, TEM of reference IONP (Senior Scientific PrecisionMRX™ 25 nm oleic acid-coated nanoparticles), concentration dependent PSF of all IONP samples, PSF and SAR of Zn-Sph and Zn-Cube mixture sample, upper right quadrant of field-dependent hysteresis curve labelled with static field strengths, and the magnetic hyperthermia temperature profiles with and without the presence of external magnetic fields. See DOI: 10.1039/c6nr01877g

Tessellated gold nanostructures from Au144(SCH2CH2Ph)60 molecular precursors and their use in organic solar cell enhancement

NASA Astrophysics Data System (ADS)

Bauld, Reg; Hesari, Mahdi; Workentin, Mark S.; Fanchini, Giovanni

2014-06-01

We report for the first time the fabrication of nanocomposite hole-blocking layers consisting of poly-3,4-ethylene-dioxythiophene:poly-styrene-sulfonate (PEDOT:PSS) thin films incorporating networks of gold nanoparticles assembled from Au144(SCH2CH2Ph)60, a molecular gold precursor. These thin films can be prepared reproducibly on indium tin oxide by spinning on it Au144(SCH2CH2Ph)60 solutions in chlorobenzene, annealing the resulting thin film at 400 °C, and subsequently spinning PEDOT:PSS on top. The use of our nanocomposite hole-blocking layers for enhancing the photoconversion efficiency of bulk heterojunction organic solar cells is demonstrated. By varying the concentration of Au144(SCH2CH2Ph)60 in the starting solution and the annealing time, different gold nanostructures were obtained ranging from individual gold nanoparticles (AuNPs) to tessellated networks of gold nanostructures (Tess-AuNPs). Improvement in organic solar cell efficiencies up to 10% relative to a reference cell is demonstrated with Tess-AuNPs embedded in PEDOT:PSS.

Synthesis of Fe3O4 cluster microspheres/graphene aerogels composite as anode for high-performance lithium ion battery

NASA Astrophysics Data System (ADS)

Zhou, Shuai; Zhou, Yu; Jiang, Wei; Guo, Huajun; Wang, Zhixing; Li, Xinhai

2018-05-01

Iron oxides are considered as attractive electrode materials because of their capability of lithium storage, but their poor conductivity and large volume expansion lead to unsatisfactory cycling stability. We designed and synthesized a novel Fe3O4 cluster microspheres/Graphene aerogels composite (Fe3O4/GAs), where Fe3O4 nanoparticles were assembled into cluster microspheres and then embedded in 3D graphene aerogels framework. In the spheres, the sufficient free space between Fe3O4 nanoparticles could accommodate the volume change during cycling process. Graphene aerogel works as flexible and conductive matrix, which can not only significantly increase the mechanical stress, but also further improve the storage properties. The Fe3O4/GAs composite as an anode material exhibits high reversible capability and excellent cyclic capacity for lithium ion batteries (LIBs). A reversible capability of 650 mAh g-1 after 500 cycles at a current density of 1 A g-1 can be maintained. The superior storage capabilities of the composites make them potential anode materials for LIBs.

TiO2 nanorods thin-films embedded with gold nanoparticles for enhanced photocatalytic activity

NASA Astrophysics Data System (ADS)

Raval, Dhyey; Jani, Margi; Mukhopadhyay, Indrajit; Ray, Abhijit

2018-05-01

This article reports on the gold nanoparticle (Au-NP) induced absorption enhancement in the hydrothermally grown titanium dioxide nanorods (TiO2-NRs). The localized surface plasmon resonance (LSPR) and transfer of electron from Au-NPs attached to the TiO2-NR have been related to their photocatalytic response. The photocurrent enhancement observed in the studies of IPCE has been explained on the basis of electrons in the conduction band of TiO2-NR. The electrons from the Au-NP to the conduction band of TiO2-NR with respect to the wavelength of the incident spectrum shows an increase in efficiency over pristine TiO2-NRs sample. Further, to investigate the role of Au-NP, an absorption spectra with its incident wavelength shows an increase in the visible spectrum in the present study. This provides an explanation for the response to the absorption of the wide bandgap semiconductor oxide which gives an opportunity to develop a hybrid structure on the transparent substrates. The better response of Au-NPs/TiO2-NRs system can be used in photocatalytic processes.

A predictive model of iron oxide nanoparticles flocculation tuning Z-potential in aqueous environment for biological application

NASA Astrophysics Data System (ADS)

Baldassarre, Francesca; Cacciola, Matteo; Ciccarella, Giuseppe

2015-09-01

Iron oxide nanoparticles are the most used magnetic nanoparticles in biomedical and biotechnological field because of their nontoxicity respect to the other metals. The investigation of iron oxide nanoparticles behaviour in aqueous environment is important for the biological applications in terms of polydispersity, mobility, cellular uptake and response to the external magnetic field. Iron oxide nanoparticles tend to agglomerate in aqueous solutions; thus, the stabilisation and aggregation could be modified tuning the colloids physical proprieties. Surfactants or polymers are often used to avoid agglomeration and increase nanoparticles stability. We have modelled and synthesised iron oxide nanoparticles through a co-precipitation method, in order to study the influence of surfactants and coatings on the aggregation state. Thus, we compared experimental results to simulation model data. The change of Z-potential and the clusters size were determined by Dynamic Light Scattering. We developed a suitable numerical model to predict the flocculation. The effects of Volume Mean Diameter and fractal dimension were explored in the model. We obtained the trend of these parameters tuning the Z-potential. These curves matched with the experimental results and confirmed the goodness of the model. Subsequently, we exploited the model to study the influence of nanoparticles aggregation and stability by Z-potential and external magnetic field. The highest Z-potential is reached up with a small external magnetic influence, a small aggregation and then a high suspension stability. Thus, we obtained a predictive model of Iron oxide nanoparticles flocculation that will be exploited for the nanoparticles engineering and experimental setup of bioassays.

Nanoparticles in natural systems I: The effective reactive surface area of the natural oxide fraction in field samples

NASA Astrophysics Data System (ADS)

Hiemstra, Tjisse; Antelo, Juan; Rahnemaie, Rasoul; van Riemsdijk, Willem H.

2010-01-01

Information on the particle size and reactive surface area of natural samples is essential for the application of surface complexation models (SCM) to predict bioavailability, toxicity, and transport of elements in the natural environment. In addition, this information will be of great help to enlighten views on the formation, stability, and structure of nanoparticle associations of natural organic matter (NOM) and natural oxide particles. Phosphate is proposed as a natively present probe ion to derive the effective reactive surface area of natural samples. In the suggested method, natural samples are equilibrated (⩾10 days) with 0.5 M NaHCO 3 (pH = 8.5) at various solid-solution ratios. This matrix fixes the pH and ionic strength, suppresses the influence of Ca 2+ and Mg 2+ ions by precipitation these in solid carbonates, and removes NOM due to the addition of activated carbon in excess, collectively leading to the dominance of the PO 4-CO 3 interaction in the system. The data have been interpreted with the charge distribution (CD) model, calibrated for goethite, and the analysis results in an effective reactive surface area (SA) and a reversibly bound phosphate loading Γ for a series of top soils. The oxidic SA varies between about 3-30 m 2/g sample for a large series of representative agricultural top soils. Scaling of our data to the total iron and aluminum oxide content (dithionite-citrate-bicarbonate extractable), results in the specific surface area between about 200-1200 m 2/g oxide for most soils, i.e. the oxide particles are nano-sized with an equivalent diameter in the order of ˜1-10 nm if considered as non-porous spheres. For the top soils, the effective surface area and the soil organic carbon fraction are strongly correlated. The oxide particles are embedded in a matrix of organic carbon (OC), equivalent to ˜1.4 ± 0.2 mg OC/m 2 oxide for many soils of the collection, forming a NOM-mineral nanoparticle association with an average NOM volume fraction of ˜80%. The average mass density of such a NOM-mineral association is ˜1700 ± 100 kg/m 3 (i.e. high-density NOM). The amount of reversibly bound phosphate is rather close to the amount of phosphate that is extractable with oxalate. The phosphate loading varies remarkably ( Γ ≈ 1-3 μmol/m 2 oxide) in the samples. As discussed in part II of this paper series ( Hiemstra et al., 2010), the phosphate loading ( Γ) of field samples is suppressed by surface complexation of NOM, where hydrophilic, fulvic, and humic acids act as a competitor for (an)ions via site competition and electrostatic interaction.

Extracellular synthesis of zinc oxide nanoparticle using seaweeds of gulf of Mannar, India

PubMed Central

2013-01-01

Background The biosynthesis of metal nanoparticles by marine resources is thought to be clean, nontoxic, and environmentally acceptable “green procedures”. Marine ecosystems are very important for the overall health of both marine and terrestrial environments. The use of natural sources like Marine biological resources essential for nanotechnology. Seaweeds constitute one of the commercially important marine living renewable resources. Seaweeds such as green Caulerpa peltata, red Hypnea Valencia and brown Sargassum myriocystum were used for synthesis of Zinc oxide nanoparticles. Result The preliminary screening of physico-chemical parameters such as concentration of metals, concentration of seaweed extract, temperature, pH and reaction time revealed that one seaweed S. myriocystum were able to synthesize zinc oxide nanoparticles. It was confirmed through the, initial colour change of the reaction mixture and UV visible spectrophotometer. The extracellular biosynthesized clear zinc oxide nanoparticles size 36 nm through characterization technique such as DLS, AFM, SEM –EDX, TEM, XRD and FTIR. The biosynthesized ZnO nanoparticles are effective antibacterial agents against Gram-positive than the Gram-negative bacteria. Conclusion Based on the FTIR results, fucoidan water soluble pigments present in S. myriocystum leaf extract is responsible for reduction and stabilization of zinc oxide nanoparticles. by this approach are quite stable and no visible changes were observed even after 6 months. These soluble elements could have acted as both reduction and stabilizing agents preventing the aggregation of nanoparticles in solution, extracellular biological synthesis of zinc oxide nanoparticles of size 36 nm. PMID:24298944

Extracellular synthesis of zinc oxide nanoparticle using seaweeds of gulf of Mannar, India.

PubMed

Nagarajan, Sangeetha; Arumugam Kuppusamy, Kumaraguru

2013-12-03

The biosynthesis of metal nanoparticles by marine resources is thought to be clean, nontoxic, and environmentally acceptable "green procedures". Marine ecosystems are very important for the overall health of both marine and terrestrial environments. The use of natural sources like Marine biological resources essential for nanotechnology. Seaweeds constitute one of the commercially important marine living renewable resources. Seaweeds such as green Caulerpa peltata, red Hypnea Valencia and brown Sargassum myriocystum were used for synthesis of Zinc oxide nanoparticles. The preliminary screening of physico-chemical parameters such as concentration of metals, concentration of seaweed extract, temperature, pH and reaction time revealed that one seaweed S. myriocystum were able to synthesize zinc oxide nanoparticles. It was confirmed through the, initial colour change of the reaction mixture and UV visible spectrophotometer. The extracellular biosynthesized clear zinc oxide nanoparticles size 36 nm through characterization technique such as DLS, AFM, SEM -EDX, TEM, XRD and FTIR. The biosynthesized ZnO nanoparticles are effective antibacterial agents against Gram-positive than the Gram-negative bacteria. Based on the FTIR results, fucoidan water soluble pigments present in S. myriocystum leaf extract is responsible for reduction and stabilization of zinc oxide nanoparticles. by this approach are quite stable and no visible changes were observed even after 6 months. These soluble elements could have acted as both reduction and stabilizing agents preventing the aggregation of nanoparticles in solution, extracellular biological synthesis of zinc oxide nanoparticles of size 36 nm.

Atomic scale observation of oxygen delivery during silver–oxygen nanoparticle catalysed oxidation of carbon nanotubes

PubMed Central

Yue, Yonghai; Yuchi, Datong; Guan, Pengfei; Xu, Jia; Guo, Lin; Liu, Jingyue

2016-01-01

To probe the nature of metal-catalysed processes and to design better metal-based catalysts, atomic scale understanding of catalytic processes is highly desirable. Here we use aberration-corrected environmental transmission electron microscopy to investigate the atomic scale processes of silver-based nanoparticles, which catalyse the oxidation of multi-wall carbon nanotubes. A direct semi-quantitative estimate of the oxidized carbon atoms by silver-based nanoparticles is achieved. A mechanism similar to the Mars–van Krevelen process is invoked to explain the catalytic oxidation process. Theoretical calculations, together with the experimental data, suggest that the oxygen molecules dissociate on the surface of silver nanoparticles and diffuse through the silver nanoparticles to reach the silver/carbon interfaces and subsequently oxidize the carbon. The lattice distortion caused by oxygen concentration gradient within the silver nanoparticles provides the direct evidence for oxygen diffusion. Such direct observation of atomic scale dynamics provides an important general methodology for investigations of catalytic processes. PMID:27406595

Single step, phase controlled, large scale synthesis of ferrimagnetic iron oxide polymorph nanoparticles by thermal plasma route and their rheological properties

NASA Astrophysics Data System (ADS)

Raut, Suyog A.; Mutadak, Pallavi R.; Kumar, Shiv; Kanhe, Nilesh S.; Huprikar, Sameer; Pol, Harshawardhan V.; Phase, Deodatta M.; Bhoraskar, Sudha V.; Mathe, Vikas L.

2018-03-01

In this paper we report single step large scale synthesis of highly crystalline iron oxide nanoparticles viz. magnetite (Fe3O4) and maghemite (γ-Fe2O3) via gas phase condensation process, where micron sized iron metal powder was used as a precursor. Selective phases of iron oxide were obtained by variation of gas flow rate of oxygen and hence partial pressure of oxygen inside the plasma reactor. Most of the particles were found to possesses average crystallite size of about 20-30 nm. The DC magnetization curves recorded indicate almost super-paramagnetic nature of the iron oxide magnetic nanoparticles. Further, iron oxide nanoparticles were analyzed using Raman spectroscopy, X-ray photoelectron spectroscopy and Mossbauer spectroscopy. In order to explore the feasibility of these nanoparticles for magnetic damper application, rheological studies have been carried out and compared with commercially available Carbonyl Iron (CI) particles. The nanoparticles obtained by thermal plasma route show improved dispersion which is useful for rheological applications.

Study on the mechanism of antibacterial action of magnesium oxide nanoparticles against foodborne pathogens

USDA-ARS?s Scientific Manuscript database

Magnesium oxide nanoparticles (MgO nanoparticles, with average size of 20 nm) have strong antibacterial activities against several important foodborne pathogens. Resazurin (a redox sensitive dye) microplate assay was used for measuring growth inhibition of bacteria treated with MgO nanoparticles. Th...

Embedded scattering eigenstates using resonant metasurfaces

NASA Astrophysics Data System (ADS)

Krasnok, Alex; Alú, Andrea

2018-06-01

Optical embedded eigenstates (EEs) are localized modes of an open structure that are compatible to radiation, yet they have infinite lifetime and diverging quality factors. Their realization in nanostructures finite in all dimensions is inherently challenging, because they require materials with extreme electromagnetic properties. Here we explore the realization of these bound states in the continuum using ultrathin metasurfaces composed of arrays of nanoparticles. We first show that arrays of lossless nanoparticles can realize the condition for EEs, and then explore the use of Ag nanoparticles coated with gain media shells to compensate material loss and revive the EE despite realistic loss in plasmonic materials. We discuss the possible experimental realization of the proposed structures, and provide useful guidelines for practical implementation in nanophotonics systems with largely enhanced light–matter interactions. These metasurfaces may lead to highly efficient lasers, filters, frequency comb generation and sensors.

Preparation and antibacterial performance testing of Ag nanoparticles embedded biological materials

NASA Astrophysics Data System (ADS)

Li, Xiaoyun; Gao, Guanhui; Sun, Chengjun; Zhu, Yaoyao; Qu, Lingyun; Jiang, Fenghua; Ding, Haibing

2015-03-01

In this study, we developed an environmentally friendly chemistry strategy to synthesize Ag nanoparticles (Ag-NPs) embedded biological material, powdered mussel shell (PMS). With the PMS as scaffolds and surfactant, Ag nanoparticles of controllable size dispersed uniformly on it via liquid chemical reduction approach. Morphologies and characteristics of synthesized Ag-NPs/PMS hybrids were analyzed with TEM, SEM and XPS. Antibacterial properties were investigated with Gram-positive bacteria (Arthrobacter sulfureus (A. sulfureus) YACS14, Staphylococcus aureus (S. aureus)) and Gram-negative bacteria (Vibrio anguillarum (V. anguillarum) MVM425, Escherichia coli (E. coli)). The antimicrobial results illustrated that Ag-NPs/PMS composites have antibacterial effect on both sea water and fresh water bacteria with a better effect on sea water bacteria. The degree of antibacterial effect is directly related to the amount of Ag released from Ag-NPs/PMS.

The facile fabrication of tunable plasmonic gold nanostructure arrays using microwave plasma

NASA Astrophysics Data System (ADS)

Hsu, Chuen-Yuan; Huang, Jing-Wen; Gwo, Shangjr; Lin, Kuan-Jiuh

2010-01-01

Fabrication of isolated noble metal nanoparticles embedded in transparent substrates is the fasting growing demand for innovative plasmonic technologies. Here we report a simple and effective methodology for the preparation of highly stable plasmonic nanoparticles embedded in a glass surface. Size-controllable (10-70 nm) Au nanoparticles were rapidly prepared when subjected to the home-microwave plasma. Accordingly, the optical extinction maximum of the localized surface plasmon resonance (LSPR) can be systematically tuned in the range 532-586 nm. We find that the plasmonic structures are exceedingly stable toward immersion in ethanol solvents and pass successfully the adhesive tape test, which makes our system highly promising for efficient transmission-LSPR nanosensors. Besides, the attractive features of substrate-bound plasmonic nanostructures include its low cost, versatility, robustness, reusability and a promising ability to make a multi-arrayed LSPR biochip.

Degradation of lindane by a novel embedded bio-nano hybrid system in aqueous environment.

PubMed

Salam, Jaseetha Abdul; Das, Nilanjana

2015-03-01

The objective of this study was to evaluate the effect of an embedded bio-nano hybrid system using nanoscale zinc oxide (n-ZnO) and lindane-degrading yeast Candida VITJzN04 for lindane degradation. Nano-embedding of the yeast was done with chemically synthesized n-ZnO particles (50 mg/mL) and was visualized by atomic force microscope (AFM) and scanning electron microscope (SEM). Nanoparticles were embedded substantially on the surfaces of the yeast cells and translocated into the cell cytoplasm without causing any lethal effect to the cell until 50 mg/mL. Lindane (600 mg/L) degradation was studied both in the individual and hybrid system. Rapid reductive-dechlorination of lindane was attained with n-ZnO under illuminated conditions, with the generation of chlorobenzene and benzene as dechlorination products. The bio-nano hybrid was found to be more effective compared to the native yeasts for lindane degradation and resulted in complete removal within 3 days. The kinetic data analysis implied that the half-life of lindane was 9 h for bio-nano hybrid and 28 h for Candida VITJzN04. The enhanced lindane degradation by bio-nano hybrid might be due to increased porosity and permeability of the yeast cell membrane, facilitating the easy entry of lindane into cell cytoplasm and n-ZnO-mediated dechlorination. To the best of our knowledge, this report, for the first time, suggests the use of n-ZnO-mediated dechlorination of lindane and the novel bio-nano hybrid system that reduces the half-life to one third of the time taken by the yeast alone. The embedded bio-nano hybrid system may be exploited as an effective remediation tool for the treatment of lindane-contaminated wastewaters.

Stabilizing Alginate Confinement and Polymer Coating of CO-Releasing Molecules Supported on Iron Oxide Nanoparticles To Trigger the CO Release by Magnetic Heating.

PubMed

Meyer, Hajo; Winkler, Felix; Kunz, Peter; Schmidt, Annette M; Hamacher, Alexandra; Kassack, Matthias U; Janiak, Christoph

2015-12-07

Maghemite (Fe2O3) iron oxide nanoparticles (IONPs) were synthesized, modified with covalent surface-bound CO-releasing molecules of a tri(carbonyl)-chlorido-phenylalaninato-ruthenium(II) complex (CORM), and coated with a dextran polymer. The time- and temperature-dependent CO release from this CORM-3 analogue was followed by a myoglobin assay. A new measurement method for the myoglobin assay was developed, based on confining "water-soluble" polymer-coated Dextran500k@CORM@IONP particles in hollow spheres of nontoxic and easily prepared calcium alginate. Dropping a mixture of Dextran500k@CORM@IONP and sodium alginate into a CaCl2 solution leads to stable hollow spheres of Ca(2+) cross-linked alginate which contain the Dextran500k@CORM@IONP particles. This "alginate-method" (i) protects CORM-3 analogues from rapid CO-displacement reactions with a protein, (ii) enables a spatial separation of the CORM from its surrounding myoglobin assay with the alginate acting as a CO-permeable membrane, and (iii) allows the use of substances with high absorptivity (such as iron oxide nanoparticles) in the myoglobin assay without interference in the optical path of the UV cell. Embedding the CORM@IONP nanoparticles in the alginate vessel represents a compartmentation of the reactive component and allows for close contact with, yet facile separation from, the surrounding myoglobin assay. The half-life of the CO release from Dextran500k@CORM@IONP particles surrounded by alginate was determined to be 890 ± 70 min at 20 °C. An acceleration of the CO release occurs at higher temperature with a half-life of 172 ± 27 min at 37 °C and 45 ± 7 min at 50 °C. The CO release can be triggered in an alternating current magnetic field (31.7 kA m(-1), 247 kHz, 39.9 mT) through local magnetic heating of the susceptible iron oxide nanoparticles. With magnetic heating at 20 °C in the bulk solution, the half-life of CO release from Dextran500k@CORM@IONP particles decreased to 155 ± 18 min without a noticeable temperature increase in the dispersion. At 37 and 50 °C, the half-life for the CO release triggered by local magnetic heating was 65 ± 5 min and 30 ± 3 min, respectively. Thus, at a physiological temperature of 37 °C, magnetic heating accelerates the CO release of the IONP-bound CORM by a factor of ∼ 2.6. The activation energy for CO release from a CORM-3 analogue was determined to be EA = 78 kJ/mol.

Improved Ionic Diffusion through the Mesoporous Carbon Skin on Silicon Nanoparticles Embedded in Carbon for Ultrafast Lithium Storage.

PubMed

An, Geon-Hyoung; Kim, Hyeonjin; Ahn, Hyo-Jin

2018-02-21

Because of their combined effects of outstanding mechanical stability, high electrical conductivity, and high theoretical capacity, silicon (Si) nanoparticles embedded in carbon are a promising candidate as electrode material for practical utilization in Li-ion batteries (LIBs) to replace the conventional graphite. However, because of the poor ionic diffusion of electrode materials, the low-grade ultrafast cycling performance at high current densities remains a considerable challenge. In the present study, seeking to improve the ionic diffusion, we propose a novel design of mesoporous carbon skin on the Si nanoparticles embedded in carbon by hydrothermal reaction, poly(methyl methacrylate) coating process, and carbonization. The resultant electrode offers a high specific discharge capacity with excellent cycling stability (1140 mA h g -1 at 100 mA g -1 after 100 cycles), superb high-rate performance (969 mA h g -1 at 2000 mA g -1 ), and outstanding ultrafast cycling stability (532 mA h g -1 at 2000 mA g -1 after 500 cycles). The battery performances are surpassing the previously reported results for carbon and Si composite-based electrodes on LIBs. Therefore, this novel approach provides multiple benefits in terms of the effective accommodation of large volume expansions of the Si nanoparticles, a shorter Li-ion diffusion pathway, and stable electrochemical conditions from a faster ionic diffusion during cycling.

Transplantation of Porcine Hepatocytes Cultured with Polylactic Acid-O-Carboxymethylated Chitosan Nanoparticles Promotes Liver Regeneration in Acute Liver Failure Rats

PubMed Central

Chen, Zhong; Chang, Renan; Guan, Weijun; Cai, Hongyu; Tang, Fei; Zhu, Wencai; Chen, Jiahui

2011-01-01

In this study, free porcine hepatocytes suspension (Group A), porcine hepatocytes embedded in collagen gel (Group B), porcine hepatocytes cultured with PLA-O-CMC nanoparticles and embedded in collagen gel (Group C), and PLA-O-CMC nanoparticles alone (Group D) were transplanted into peritoneal cavity of ALF rats, respectively. The result showed that plasma HGF levels were elevated post-transplantation with a peak at 12 hr. The rats in Group C showed highest plasma HGF levels at 2, 6, 12, 24 and 36 hr post-transplantation and lowest HGF level at 48 hr. Plasma VEGF levels were elevated at 48 hr post-transplantation with a peak at 72 hr. The rats in Group C showed highest plasma HGF levels at 48, 72, and 96 hr post-transplantation. The liver functions in Group C were recovered most rapidly. Compared with Group B, Group C had significant high liver Kiel 67 antigen labeling index (Ki-67 LI) at day 1 post-HTx (P < .05). Ki-67 LI in groups B and C was higher than that in groups A and D at days 5 and 7 post-HTx. In conclusion, intraperitoneal transplantation of porcine hepatocytes cultured with PLA-O-CMC nanoparticles and embedded in collagen gel can promote significantly liver regeneration in ALF rats. PMID:21603218

Synthesis, characterization and antibacterial activity of hybrid chitosan-cerium oxide nanoparticles: As a bionanomaterials.

PubMed

Senthilkumar, R P; Bhuvaneshwari, V; Ranjithkumar, R; Sathiyavimal, S; Malayaman, V; Chandarshekar, B

2017-11-01

The hybrid chitosan cerium oxide nanoparticles were prepared for the first time by green chemistry approach using plant leaf extract. The intense peak observed around 292nm in the UV-vis spectrum indicate the formation of cerium oxide nanoparticles. The XRD pattern revealed that the hybrid chitosan-cerium oxide nanoparticles have a polycrystalline structure with cubic fluorite phase. The FTIR spectrum of prepared samples showed the formation of Ce-O bonds and chitosan main chains COC and CO. The FESEM image of hybrid chitosan cerium oxide nanoparticles revealed that the particles are spherical in shape with grains size varying from 23.12nm to 89.91nm. EDAX analysis confirmed the presence of Ce, O, C and N elements in the prepared sample. TEM images showed that the prepared hybrid chitosan-cerium oxide nanoparticles are predominantly uniform in size and most of the particles are spherical in shape with less agglomeration and the particles size varies from 3.61nm to 24.40nm. The prepared chitosan cerium oxide nanoparticles of 50μL concentration showed good antibacterial properties against test pathogens, which was confirmed by the FESEM analysis. The prepared small particle size facilitate that these hybrid ChiCO 2 NPs could effectively be used in biomedical applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Biological consequences from interaction of nanosized titanium(iv) oxides with defined human blood components

NASA Astrophysics Data System (ADS)

Stella, Aaron

The utility of engineered nanomaterials is growing, particularly the titanium(iv) oxide (titanium dioxide, TiO2) nanoparticles. TiO 2 is very useful for brightening paints, and coloring foods. Nano-sized TiO2 is also useful for sunscreens, cosmetics, and can be utilized as a photocatalyst. However, the nanometer size of the TiO2 nanoparticle is a characteristic that may contribute oxidative stress to red blood cells (RBCs) in humans. This study utilized screening methods to evaluate different forms of TiO2 nanoparticles which differ by primary particle size, specific surface area, crystalline phase, and surface polarity. RBCs are rich in the intracellular antioxidant glutathione (GSH). HPLC analysis revealed that some TiO2 nanoparticles caused oxidation of GSH to glutathione disulfide (GSSG). Vitamin E is a major membrane-bound antioxidant. Vitamin E levels were then determined by HPLC in the RBC membrane after exposure to TiO2 nanoparticles. The HPLC results showed that each nanoparticle oxidized RBC glutathione and membrane vitamin E at different rates. When hemoglobin was mixed with each TiO2 nanoparticle, hemoglobin was adsorbed at varying rates to the surface of the nanoparticles. Similarly, the aminothiol homocysteine was also adsorbed at different rates by the TiO2 nanoparticles. Using light microscopy, some TiO2 nanoparticles caused the formation of RBC aggregates which significantly changed the RBC morphology. The aggregation data was quantified using a hemacytometer. The TiO2 nanoparticles also caused hemolysis of RBCs. Hemolysis is considered to be a toxic endpoint for RBCs. Changes in the nucleated lymphocyte gene expression of certain oxidative stress genes were also observed using real-time polymerase chain reaction (qPCR). The data indicates that RBCs can ultimately be hemolyzed by biological oxidative damage resulting from a combination of oxidative mechanisms. Additionally, the TiO2 nanoparticles demonstrated the ability to adsorb biomolecules to their surface which could be useful for nanomedicine purposes or biosensing applications. The changes in lymphocyte gene expression at different doses indicate that these TiO2 nanoparticles are capable of disrupting nuclear activity. The use of multiple screening methods provided an effective approach to evaluate nano-bio interactions. The use of a biologically-relevant matrix combined with specific detection methods yielded results which accurately predict biological adversity.

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…

Characterization of injected aluminum oxide nanoparticle clouds in an rf discharge

NASA Astrophysics Data System (ADS)

Krüger, Harald; Killer, Carsten; Schütt, Stefan; Melzer, André

2018-02-01

An experimental setup to deagglomerate and insert nanoparticles into a radio frequency discharge has been developed to confine defined aluminum oxide nanoparticles in a dusty plasma. For the confined particle clouds we have measured the spatially resolved in situ size and density distributions. Implementing the whole plasma chamber into the sample volume of an FTIR spectrometer the infrared spectrum of the confined aluminum oxide nanoparticles has been obtained. We have investigated the dependency of the absorbance of the nanoparticles in terms of plasma power, pressure and cloud shape. The particles’ infrared phonon resonance has been identified.

Carbon nanotube-supported Au-Pd alloy with cooperative effect of metal nanoparticles and organic ketone/quinone groups as a highly efficient catalyst for aerobic oxidation of amines.

PubMed

Deng, Weiping; Chen, Jiashu; Kang, Jincan; Zhang, Qinghong; Wang, Ye

2016-05-21

Functionalised carbon nanotube (CNT)-supported Au-Pd alloy nanoparticles were highly efficient catalysts for the aerobic oxidation of amines. We achieved the highest turnover frequencies (>1000 h(-1)) for the oxidative homocoupling of benzylamine and the oxidative dehydrogenation of dibenzylamine. We discovered a cooperative effect between Au-Pd nanoparticles and ketone/quinone groups on CNTs.

Impact of metal and metal oxide nanoparticles on plant: A critical review

NASA Astrophysics Data System (ADS)

Rastogi, Anshu; Zivcak, Marek; Sytar, Oksana; Kalaji, Hazem M.; He, Xiaolan; Mbarki, Sonia; Brestic, Marian

2017-10-01

An increasing need of nanotechnology in various industries may cause a huge environment dispersion of nanoparticles in coming years. A concern about nanoparticles interaction with flora and fauna is raised due to a growing load of it in the environment. In recent years, several investigators have shown impact of nanoparticles on plant growth and its accumulation in food source. This review examines the research performed in the last decade to show how metal and metal oxide nanoparticles are influencing the plant metabolisms. We addressed here, the impact of nanoparticle on plant in relation to its size, concentration, and exposure methodology. Based on the available reports, we proposed oxidative burst as a general mechanism through which the toxic effects of nanoparticles are spread in plants. This review summarises the current understanding and the future possibilities of plant-nanoparticle research.

Magnetic Nanoparticles: Material Engineering and Emerging Applications in Lithography and Biomedicine

PubMed Central

Bao, Yuping; Wen, Tianlong; Samia, Anna Cristina S.; Khandhar, Amit; Krishnan, Kannan M.

2015-01-01

We present an interdisciplinary overview of material engineering and emerging applications of iron oxide nanoparticles. We discuss material engineering of nanoparticles in the broadest sense, emphasizing size and shape control, large-area self-assembly, composite/hybrid structures, and surface engineering. This is followed by a discussion of several non-traditional, emerging applications of iron oxide nanoparticles, including nanoparticle lithography, magnetic particle imaging, magnetic guided drug delivery, and positive contrast agents for magnetic resonance imaging. We conclude with a succinct discussion of the pharmacokinetics pathways of iron oxide nanoparticles in the human body –– an important and required practical consideration for any in vivo biomedical application, followed by a brief outlook of the field. PMID:26586919

Magnetic Nanoparticles: Material Engineering and Emerging Applications in Lithography and Biomedicine.

PubMed

Bao, Yuping; Wen, Tianlong; Samia, Anna Cristina S; Khandhar, Amit; Krishnan, Kannan M

2016-01-01

We present an interdisciplinary overview of material engineering and emerging applications of iron oxide nanoparticles. We discuss material engineering of nanoparticles in the broadest sense, emphasizing size and shape control, large-area self-assembly, composite/hybrid structures, and surface engineering. This is followed by a discussion of several non-traditional, emerging applications of iron oxide nanoparticles, including nanoparticle lithography, magnetic particle imaging, magnetic guided drug delivery, and positive contrast agents for magnetic resonance imaging. We conclude with a succinct discussion of the pharmacokinetics pathways of iron oxide nanoparticles in the human body -- an important and required practical consideration for any in vivo biomedical application, followed by a brief outlook of the field.

Iron oxide nanoparticles stabilized with dendritic polyglycerols as selective MRI contrast agents

NASA Astrophysics Data System (ADS)

Nordmeyer, Daniel; Stumpf, Patrick; Gröger, Dominic; Hofmann, Andreas; Enders, Sven; Riese, Sebastian B.; Dernedde, Jens; Taupitz, Matthias; Rauch, Ursula; Haag, Rainer; Rühl, Eckart; Graf, Christina

2014-07-01

Monodisperse small iron oxide nanoparticles functionalized with dendritic polyglycerol (dPG) or dendritic polyglycerol sulfate (dPGS) are prepared. They are highly stable in aqueous solutions as well as physiological media. In particular, oleic acid capped iron oxide particles (core diameter = 11 +/- 1 nm) were modified by a ligand exchange process in a one pot synthesis with dPG and dPGS bearing phosphonate as anchor groups. Dynamic light scattering measurements performed in water and different biological media demonstrate that the hydrodynamic diameter of the particles is only slightly increased by the ligand exchange process resulting in a final diameter of less than 30 nm and that the particles are stable in these media. It is also revealed by magnetic resonance studies that their magnetic relaxivity is reduced by the surface modification but it is still sufficient for high contrast magnetic resonance imaging (MRI). Additionally, incubation of dPGS functionalized iron oxide nanoparticles with human umbilical vein endothelial cells showed a 50% survival at 85 nM (concentration of nanoparticles). Surface plasmon resonance (SPR) studies demonstrate that the dPGS functionalized iron oxide nanoparticles inhibit L-selectin ligand binding whereas the particles containing only dPG do not show this effect. Experiments in a flow chamber with human myelogenous leukemia cells confirmed L-selectin inhibition of the dPGS functionalized iron oxide nanoparticles and with that the L-selectin mediated leukocyte adhesion. These results indicate that dPGS functionalized iron oxide nanoparticles are a promising contrast agent for inflamed tissue probed by MRI.Monodisperse small iron oxide nanoparticles functionalized with dendritic polyglycerol (dPG) or dendritic polyglycerol sulfate (dPGS) are prepared. They are highly stable in aqueous solutions as well as physiological media. In particular, oleic acid capped iron oxide particles (core diameter = 11 +/- 1 nm) were modified by a ligand exchange process in a one pot synthesis with dPG and dPGS bearing phosphonate as anchor groups. Dynamic light scattering measurements performed in water and different biological media demonstrate that the hydrodynamic diameter of the particles is only slightly increased by the ligand exchange process resulting in a final diameter of less than 30 nm and that the particles are stable in these media. It is also revealed by magnetic resonance studies that their magnetic relaxivity is reduced by the surface modification but it is still sufficient for high contrast magnetic resonance imaging (MRI). Additionally, incubation of dPGS functionalized iron oxide nanoparticles with human umbilical vein endothelial cells showed a 50% survival at 85 nM (concentration of nanoparticles). Surface plasmon resonance (SPR) studies demonstrate that the dPGS functionalized iron oxide nanoparticles inhibit L-selectin ligand binding whereas the particles containing only dPG do not show this effect. Experiments in a flow chamber with human myelogenous leukemia cells confirmed L-selectin inhibition of the dPGS functionalized iron oxide nanoparticles and with that the L-selectin mediated leukocyte adhesion. These results indicate that dPGS functionalized iron oxide nanoparticles are a promising contrast agent for inflamed tissue probed by MRI. Electronic supplementary information (ESI) available: A detailed description of the synthesis of the ligands as well as the preparation and functionalization of the iron oxide nanoparticles including their physico-chemical characterization are presented. Further, details of the cell experiments and the SPR experiments are given. Two representative movies are provided showing leukocyte rolling on the ligand coated surface of the flow chamber. See DOI: 10.1039/c3nr04793h

Optical detection of gold nanoparticles in a prostate-shaped porcine phantom.

PubMed

Grabtchak, Serge; Tonkopi, Elena; Whelan, William M

2013-07-01

Gold nanoparticles can be used as molecular contrast agents binding specifically to cancer sites and thus delineating tumor regions. Imaging gold nanoparticles deeply embedded in tissues with optical techniques possesses significant challenges due to multiple scattering of optical photons that blur the obtained images. Both diagnostic and therapeutic applications can benefit from a minimally invasive technique that can identify, localize, and quantify the payloads of gold nanoparticles deeply embedded in biological tissues. An optical radiance technique is applied to map localized inclusions of gold nanorods in 650- to 900-nm spectral range in a porcine phantom that mimics prostate geometry. Optical radiance defines a variation in the angular density of photons impinging on a selected point in the tissue from various directions. The inclusions are formed by immersing a capillary filled with gold nanorods in the phantom at increasing distances from the detecting fiber. The technique allows the isolation of the spectroscopic signatures of the inclusions from the background and identification of inclusion locations in the angular domain. Detection of ∼4×1010 gold nanoparticles or 0.04  mg Au/mL (detector-inclusion separation 10 mm, source-detector separation 15 mm) in the porcine tissue is demonstrated. The encouraging results indicate a promising potential of radiance spectroscopy in early prostate cancer diagnostics with gold nanoparticles.

Ultra-fast self-assembly and stabilization of reactive nanoparticles in reduced graphene oxide films

PubMed Central

Chen, Yanan; Egan, Garth C.; Wan, Jiayu; Zhu, Shuze; Jacob, Rohit Jiji; Zhou, Wenbo; Dai, Jiaqi; Wang, Yanbin; Danner, Valencia A.; Yao, Yonggang; Fu, Kun; Wang, Yibo; Bao, Wenzhong; Li, Teng; Zachariah, Michael R.; Hu, Liangbing

2016-01-01

Nanoparticles hosted in conductive matrices are ubiquitous in electrochemical energy storage, catalysis and energetic devices. However, agglomeration and surface oxidation remain as two major challenges towards their ultimate utility, especially for highly reactive materials. Here we report uniformly distributed nanoparticles with diameters around 10 nm can be self-assembled within a reduced graphene oxide matrix in 10 ms. Microsized particles in reduced graphene oxide are Joule heated to high temperature (∼1,700 K) and rapidly quenched to preserve the resultant nano-architecture. A possible formation mechanism is that microsized particles melt under high temperature, are separated by defects in reduced graphene oxide and self-assemble into nanoparticles on cooling. The ultra-fast manufacturing approach can be applied to a wide range of materials, including aluminium, silicon, tin and so on. One unique application of this technique is the stabilization of aluminium nanoparticles in reduced graphene oxide film, which we demonstrate to have excellent performance as a switchable energetic material. PMID:27515900

Nanostructured magnesium oxide as cure activator for polychloroprene rubber.

PubMed

Kar, Sritama; Bhowmick, Anil K

2009-05-01

The aim of this research was to synthesize magnesium oxide nanoparticles and to use them as cure activator for polychloroprene rubber (CR). The effects of counterions of magnesium salts on the homogeneous phase precipitation reaction to control size, monodispersity, crystallinity, and morphology of Mg(OH)2 nanoparticles were also investigated. Magnesium oxide nanoparticles were synthesized by optimizing the calcination temperature of Mg(OH)2 nanoparticles. Finally, the MgO nanoparticles were dispersed in polychloroprene rubber (CR) solution along with zinc oxide (ZnO) powder. The influence of MgO nanoparticles on the mechanical, dynamic mechanical and thermal properties of the resulting nanocomposites was quantified. The modulus and strength of ZnO-cured polychloroprene rubber with 4% MgO nanoparticles appeared to be superior to those with ZnO particles or ZnO with rubber grade MgO particles. These composites were further characterized by transmission electron microscopy and infrared spectroscopy in order to understand the morphology of the resulting system and the load transfer mechanism.

Microbially-mediated method for synthesis of non-oxide semiconductor nanoparticles

DOEpatents

Phelps, Tommy J.; Lauf, Robert J.; Moon, Ji Won; Rondinone, Adam J.; Love, Lonnie J.; Duty, Chad Edward; Madden, Andrew Stephen; Li, Yiliang; Ivanov, Ilia N.; Rawn, Claudia Jeanette

2014-06-24

The invention is directed to a method for producing non-oxide semiconductor nanoparticles, the method comprising: (a) subjecting a combination of reaction components to conditions conducive to microbially-mediated formation of non-oxide semiconductor nanoparticles, wherein said combination of reaction components comprises i) anaerobic microbes, ii) a culture medium suitable for sustaining said anaerobic microbes, iii) a metal component comprising at least one type of metal ion, iv) a non-metal component containing at least one non-metal selected from the group consisting of S, Se, Te, and As, and v) one or more electron donors that provide donatable electrons to said anaerobic microbes during consumption of the electron donor by said anaerobic microbes; and (b) isolating said non-oxide semiconductor nanoparticles, which contain at least one of said metal ions and at least one of said non-metals. The invention is also directed to non-oxide semiconductor nanoparticle compositions produced as above and having distinctive properties.

Soft template strategy to synthesize iron oxide-titania yolk-shell nanoparticles as high-performance anode materials for lithium-ion battery applications.

PubMed

Lim, Joohyun; Um, Ji Hyun; Ahn, Jihoon; Yu, Seung-Ho; Sung, Yung-Eun; Lee, Jin-Kyu

2015-05-18

Yolk-shell-structured nanoparticles with iron oxide core, void, and a titania shell configuration are prepared by a simple soft template method and used as the anode material for lithium ion batteries. The iron oxide-titania yolk-shell nanoparticles (IO@void@TNPs) exhibit a higher and more stable capacity than simply mixed nanoparticles of iron oxide and hollow titania because of the unique structure obtained by the perfect separation between iron oxide nanoparticles, in combination with the adequate internal void space provided by stable titania shells. Moreover, the structural effect of IO@void@TNPs clearly demonstrates that the capacity retention value after 50 cycles is approximately 4 times that for IONPs under harsh operating conditions, that is, when the temperature is increased to 80 °C. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Composite anode for lithium ion batteries

DOEpatents

de Guzman, Rhet C.; Ng, K.Y. Simon; Salley, Steven O.

2018-03-06

A composite anode for a lithium-ion battery is manufactured from silicon nanoparticles having diameters mostly under 10 nm; providing an oxide layer on the silicon nanoparticles; dispersing the silicon nanoparticles in a polar liquid; providing a graphene oxide suspension; mixing the polar liquid containing the dispersed silicone nanoparticles with the graphene oxide suspension to obtain a composite mixture; probe-sonicating the mixture for a predetermined time; filtering the composite mixture to obtain a solid composite; drying the composite; and reducing the composite to obtain graphene and silicon.

The disclosed transformation of pre-sputtered Ti films into nanoparticles via controlled thermal oxidation

NASA Astrophysics Data System (ADS)

Awad, M. A.; Raaif, M.

2018-05-01

Nanoparticles of TiO2 were successfully prepared from pre-sputtered Ti films using the controlled thermal oxidation. The effect of oxidation temperature on structural, morphological and optical properties in addition to photocatalysis activity of the sputtered films was tested and explained. Analysis of XRD and EDAX elucidated the enhancement in crystallization and oxygen content with the increase of oxidation temperature. SEM depicted the formation of very fine nanoparticles with no specific border on the films oxidized at 550 and 600 °C, whilst crystallites with larger size of approximately from 16 to 23 nm have been observed for the film oxidized at 650 °C. Both optical transmission and refractive index were increased with increasing the oxidation temperature. A red shift in the absorption edge was obtained for the films oxidized at 650 °C compared to that oxidized at 600 °C. The photocatalysis tests demonstrated the priority of 600 °C nanoparticle films to decompose methyl orange (MO) more than 650 °C treated film.

Antibacterial applications of α-Fe2O3/Co3O4 nanocomposites and study of their structural, optical, magnetic and cytotoxic characteristics

NASA Astrophysics Data System (ADS)

Bhushan, Mayank; Kumar, Yogesh; Periyasamy, Latha; Viswanath, Annamraju Kasi

2018-02-01

Owing to their multiple mechanisms of bactericidal activity, inorganic metal oxides and hybrid metal oxide nanocomposites may serve as a new class of effective disinfectants. Among metal oxide nanoparticles, iron oxide nanoparticles exhibit minimal or no cytotoxicity to human cells with very efficient bactericidal properties over a wide spectrum of bacteria. This paper presents the very first report on antibacterial properties of novel nanocomposites of iron oxide and cobalt oxide nanoparticles against pathogenic bacterial strains B. subtilis, S. aureus, E.coli and S. typhi. The enhanced bactericidal activity of the Fe/Co oxide nanocomposite was the result of synergistic effect of iron oxide and cobalt oxide nanoparticles. The nanocomposites were synthesized using co-precipitation route with increasing cobalt content in the sample and further characterized using XRD, TEM, Raman and VSM to investigate structural, optical and magnetic properties of the prepared nanocomposites, respectively. Also, the prepared nanocomposites were highly biocompatible and found non-toxic to human cell line MCF7.

Zinc Oxide Nanoparticles for Revolutionizing Agriculture: Synthesis and Applications

PubMed Central

Sabir, Sidra; Arshad, Muhammad

2014-01-01

Nanotechnology is the most innovative field of 21st century. Extensive research is going on for commercializing nanoproducts throughout the world. Due to their unique properties, nanoparticles have gained considerable importance compared to bulk counterparts. Among other metal nanoparticles, zinc oxide nanoparticles are very much important due to their utilization in gas sensors, biosensors, cosmetics, drug-delivery systems, and so forth. Zinc oxide nanoparticles (ZnO NPs) also have remarkable optical, physical, and antimicrobial properties and therefore have great potential to enhance agriculture. As far as method of formation is concerned, ZnO NPs can be synthesized by several chemical methods such as precipitation method, vapor transport method, and hydrothermal process. The biogenic synthesis of ZnO NPs by using different plant extracts is also common nowadays. This green synthesis is quite safe and ecofriendly compared to chemical synthesis. This paper elaborates the synthesis, properties, and applications of zinc oxide nanoparticles. PMID:25436235

Zinc oxide nanoparticles for revolutionizing agriculture: synthesis and applications.

PubMed

Sabir, Sidra; Arshad, Muhammad; Chaudhari, Sunbal Khalil

2014-01-01

Nanotechnology is the most innovative field of 21st century. Extensive research is going on for commercializing nanoproducts throughout the world. Due to their unique properties, nanoparticles have gained considerable importance compared to bulk counterparts. Among other metal nanoparticles, zinc oxide nanoparticles are very much important due to their utilization in gas sensors, biosensors, cosmetics, drug-delivery systems, and so forth. Zinc oxide nanoparticles (ZnO NPs) also have remarkable optical, physical, and antimicrobial properties and therefore have great potential to enhance agriculture. As far as method of formation is concerned, ZnO NPs can be synthesized by several chemical methods such as precipitation method, vapor transport method, and hydrothermal process. The biogenic synthesis of ZnO NPs by using different plant extracts is also common nowadays. This green synthesis is quite safe and ecofriendly compared to chemical synthesis. This paper elaborates the synthesis, properties, and applications of zinc oxide nanoparticles.

Formation of 2D nanoparticles with block structure in simultaneous electric explosion of conductors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kryzhevich, Dmitrij S., E-mail: kryzhev@ispms.ru, E-mail: kost@ispms.ru; Zolnikov, Konstantin P., E-mail: kryzhev@ispms.ru, E-mail: kost@ispms.ru; Abdrashitov, Andrei V.

2014-11-14

A molecular dynamics simulation of nanoparticle formation in simultaneous electric explosion of conductors is performed. Interatomic interaction is described using potentials calculated in the framework of the embedded atom method. High-rate heating results in failure of the conductors with the formation of nanoparticles. The influence of the heating rate, temperature distribution over the specimen cross-section and the distance between simultaneously exploded conductors on the structure of formed nanoparticles is studied. The calculation results show that the electric explosion of conductors allows the formation of nanoparticles with block structure.

Photosensitized H2 Production Using a Zinc Porphyrin-Substituted Protein, Platinum Nanoparticles, and Ascorbate with No Electron Relay: Participation of Good's Buffers.

PubMed

Clark, Emily R; Kurtz, Donald M

2017-04-17

Development of efficient light-driven splitting of water, 2H 2 O → 2H 2 + O 2 , often attempts to optimize photosensitization of the reductive and oxidative half-reactions individually. Numerous homogeneous and heterogeneous systems have been developed for photochemical stimulation of the reductive half reaction, 2H + + 2e - → H 2 . These systems generally consist of various combinations of a H + reduction catalyst, a photosensitizer (PS), and a "sacrificial" electron donor. Zinc(II)-porphyrins (ZnPs) have frequently been used as PSs for H 2 generation, but they are subject to various self-quenching processes in aqueous solutions. Colloidal platinum in nanoparticle form (Pt NP) is a classical H + reduction catalyst using ZnP photosensitizers, but efficient photosensitized H 2 generation requires an electron relay molecule between ZnP and Pt NP. The present report describes an aqueous system for visible (white) light-sensitized generation of H 2 using a protein-embedded Zn(II)-protoporphyrin IX as PS and Pt NP as H + reduction catalyst without an added electron relay. This system operated efficiently in piperazino- and morpholino-alkylsulfonic acid (Good's buffers), which served as sacrificial electron donors. The system also required ascorbate at relatively modest concentrations, which stabilized the Zn(II)-protoporphyrin IX against photodegradation. In the absence of an electron relay molecule, the photosensitized H 2 generation must involve formation of at least a transient complex between a protein-embedded Zn(II)-protoporphyrin IX species and Pt NP.

Synthesis and characterization of chitosan-coated magnetite nanoparticles and their application in curcumin drug delivery

NASA Astrophysics Data System (ADS)

Nui Pham, Xuan; Phuoc Nguyen, Tan; Nhung Pham, Tuyet; Thuy Nga Tran, Thi; Van Thi Tran, Thi

2016-12-01

In this work anti-cancer drug curcumin-loaded superparamagnetic iron oxide (Fe3O4) nanoparticles was modified by chitosan (CS). The magnetic iron oxide nanoparticles were synthesized by using reverse micro-emulsion (water-in-oil) method. The magnetic nanoparticles without loaded drug and drug-loaded magnetic nanoparticles were characterized by XRD, FTIR, TG-DTA, SEM, TEM, and VSM techniques. These nanoparticles have almost spherical shape and their diameter varies from 8 nm to 17 nm. Measurement of VSM at room temperature showed that iron oxide nanoparticles have superparamagnetic properties. In vitro drug loading and release behavior of curcumin drug-loaded CS-Fe3O4 nanoparticles were studied by using UV-spectrophotometer. In addition, the cytotoxicity of the modified nanoparticles has shown anticancer activity against A549 cell with IC50 value of 73.03 μg/ml. Therefore, the modified magnetic nanoparticles can be used as drug delivery carriers on target in the treatment of cancer cells.

Superior high-rate capability of Na3(VO(0.5))2(PO4)2F2 nanoparticles embedded in porous graphene through the pseudocapacitive effect.

PubMed

Xiang, Xingde; Lu, Qiongqiong; Han, Mo; Chen, Jun

2016-03-04

Na3(VO(0.5))2(PO4)2F2 nanoparticles embedded in porous graphene have been reported as a superior high-rate cathode material for sodium-ion batteries, exhibiting an excellent electrochemical performance with a high reversible capacity of 100 mA h g(-1) at 1 C, 77 mA h g(-1) at 50 C, and a capacity retention of 73% after 1000 cycles at 50 C. In particular, a significant contribution of the pseudocapacitive effect to the Na-storage capacity has been found for the first time.

MoS2 embedded TiO2 nanoparticles for concurrent role of adsorption and photocatalysis

NASA Astrophysics Data System (ADS)

Pal, Arnab; Jana, Tushar K.; Chatterjee, Kuntal

2018-04-01

In this work, MoS2 embedded TiO2 nanoparticles, synthesized through hydrothermal process, was successfully employed to remove organic pollutant dye like methylene blue(MB) through adsorption and as well as through photocatalysis under visible light irradiation. The system was characterized by structural and morphological study. The adsorption and photocatalytic study of MB were evaluated with different concentrations of dye in aqueous solution. This work brings the MoS2-TiO2 nanostructure as excellent adsorbent as well as efficient photocatalyst materials which can be used for organic dye removal towards waste-water treatment.

Plasmonic extinction in gold nanoparticle-polymer films as film thickness and nanoparticle separation decrease below resonant wavelength

NASA Astrophysics Data System (ADS)

Dunklin, Jeremy R.; Bodinger, Carter; Forcherio, Gregory T.; Keith Roper, D.

2017-01-01

Plasmonic nanoparticles embedded in polymer films enhance optoelectronic properties of photovoltaics, sensors, and interconnects. This work examined optical extinction of polymer films containing randomly dispersed gold nanoparticles (AuNP) with negligible Rayleigh scattering cross-sections at particle separations and film thicknesses less than (sub-) to greater than (super-) the localized surface plasmon resonant (LSPR) wavelength, λLSPR. Optical extinction followed opposite trends in sub- and superwavelength films on a per nanoparticle basis. In ˜70-nm-thick polyvinylpyrrolidone films containing 16 nm AuNP, measured resonant extinction per particle decreased as particle separation decreased from ˜130 to 76 nm, consistent with trends from Maxwell Garnett effective medium theory and coupled dipole approximation. In ˜1-mm-thick polydimethylsiloxane films containing 16-nm AuNP, resonant extinction per particle plateaued at particle separations ≥λLSPR, then increased as particle separation radius decreased from ˜514 to 408 nm. Contributions from isolated particles, interparticle interactions and heterogeneities in sub- and super-λLSPR films containing AuNP at sub-λLSPR separations were examined. Characterizing optoplasmonics of thin polymer films embedded with plasmonic NP supports rational development of optoelectronic, biomedical, and catalytic activity using these nanocomposites.

Fabrication and Luminescence Characterization of a Silica Nanomatrix Embedded with NaYF4:Yb:Er:Tm@NaGdF4/Fe3O4 Nanoparticles

NASA Astrophysics Data System (ADS)

Thangaraju, Dheivasigamani; Santhana, Vedi; Matsuda, Satoshi; Hayakawa, Yasuhiro

2018-05-01

Hexagonal NaYF4:Yb:Er:Tm@NaGdF4 core-shell nanocrystals were synthesized using a seed mediated hot injection method, and monodispersed Fe3O4 (4 nm) nanoparticles were prepared from iron(II) actylacetonate by a precursor thermal decomposition method. Structural and morphology verified NaYF4:Yb:Er:Tm@NaGdF4 and Fe3O4 nanoparticles were utilized for the preparation of NaYF4:Yb:Er:Tm@NaGdF4/Fe3O4@SiO2 nanocomposite using a micro-emulsion method. Existence of Fe3O4 in NaYF4:Yb:Er:Tm@NaGdF4 in SiO2 nano-spheres were confirmed with transmission electron microscopy. Luminescence measurement revealed that NaYF4:Yb:Er:Tm@NaGdF4 exhibited strong emissions at green and red regions, in addition to a weak blue emission also observed under 980 nm excitation. Up-conversion emission of the nanoparticle-embedded silica nanocomposite showed that the up-conversion emission was not affected by Fe3O4 nanoparticles.

The Effect of Size and Size Distribution on the Oxidation Kinetics and Plasmonics of Nanoscale Ag Particles

DTIC Science & Technology

2010-01-01

examine the stability to oxidation of the silver nanoparticles , SERS measurements were carried out on a single dielectric ZnO nanowire core/silver...employed a simple and effective electroless (EL) plating approach to produce silver nanoparticles (NPs) on bare silicon, on dielectric ZnO nanowires (NWs...nature of silver, the Ag surface is easily oxidized in the air. Hence, it is important to understand the silver nanoparticle oxidation processes in

FATE, TRANSFORMATION AND TOXICITY OF MANUFACTURED NANOMATERIALS IN DRINKING WATER

EPA Science Inventory

Studies were conducted using several types of commercial metal oxide nanoparticles (two types of titanium dioxide, iron(III) oxide, zinc oxide, nickel oxide, and silica in powder form or liquid suspensions), functionalized quantum dots, lab-synthesized hematite nanoparticles a...

Antibiotic loading and release studies of LSMO nanoparticles embedded in an acrylic polymer

NASA Astrophysics Data System (ADS)

Biswas, Sonali; Keshri, Sunita; Goswami, Sudipta; Isaac, Jinu; Ganguly, Swastika; Perov, Nikolai

2016-12-01

In this paper, we present the drug loading and release works of ? (LSMO) manganite nanoparticles (NPs). The LSMO NPs, grown using the sol-gel method, were embedded in an acrylic interpenetrating polymer network to make the sample applicable for biomedical purposes. The results of scanning electron microscopy showed that these NPs were well dispersed in the polymer. The grain size of these NPs lies in the range of 25-45 nm, as confirmed by transmission electron microscopy. The measurements of DC magnetization and hysteresis loops reveal that the basic magnetic behaviour of the LSMO NPs remained almost unaltered even after embedding in polymer, but with lower saturation value of magnetization. The drug loading and release studies of the grown sample were carried out using an antibiotic, ciprofloxacin. The minimum inhibitory effect of the sample loaded with this drug has exhibited high activity against different strains of bacteria, comparable to the pure ciprofloxacin.

A Hybrid Density Functional Theory/Molecular Mechanics Approach for Linear Response Properties in Heterogeneous Environments.

PubMed

Rinkevicius, Zilvinas; Li, Xin; Sandberg, Jaime A R; Mikkelsen, Kurt V; Ågren, Hans

2014-03-11

We introduce a density functional theory/molecular mechanical approach for computation of linear response properties of molecules in heterogeneous environments, such as metal surfaces or nanoparticles embedded in solvents. The heterogeneous embedding environment, consisting from metallic and nonmetallic parts, is described by combined force fields, where conventional force fields are used for the nonmetallic part and capacitance-polarization-based force fields are used for the metallic part. The presented approach enables studies of properties and spectra of systems embedded in or placed at arbitrary shaped metallic surfaces, clusters, or nanoparticles. The capability and performance of the proposed approach is illustrated by sample calculations of optical absorption spectra of thymidine absorbed on gold surfaces in an aqueous environment, where we study how different organizations of the gold surface and how the combined, nonadditive effect of the two environments is reflected in the optical absorption spectrum.

Nanohybrids of magnetic iron-oxide particles in hydrophobic organoclays for oil recovery.

PubMed

Hsu, Ru-Siou; Chang, Wen-Hsin; Lin, Jiang-Jen

2010-05-01

Nanohybrids with magnetic iron-oxide nanoparticles (FeNPs) embedded in the multilayered silicate clay were synthesized by in situ Fe(2+)/Fe(3+) coprecipitation. The natural clay, sodium montmorillonite (Na(+)-MMT), was first modified with hydrophobic poly(oxypropylene)amine salts (POP at 2000 and 4000 g/mol M(w)). The two POP-intercalated organoclays, with a silicate interlayer expansion from 1.2 to 5.2 and 9.2 nm, respectively, are suitable for embedding FeNPs. The presence of POP organics in layered structure created the space for intercalating with FeNPs of 2-4 nm in diameter, observed by transmission electronic microscope. The synthesized nanohybrids of POP4000/MMT-FeNP was composed of 17% iron oxide and 51 wt % POP within the silicate basal spacing of 5.0 nm. In contrast, the lower molecular weight of POP2000 intercalated MMT failed to encapsulate FeNPs in a significant amount, but resulting a "crowding-out effect" that caused the silicate interlayer space to shrink from 5.2 to 1.8 nm because of the replacement of the POP salt by Fe(2+)/Fe(3+) ions. The synthesis required the use of high molecular weight POP4000 and low temperatures (<4 degrees C) for a better dispersion in the reaction medium. The presence of POP in the layered silicate facilitated a homogeneous POP/MMT in water, associating with Fe(2+)/Fe(3+) ions and spatially accommodating for the subsequently generated FeNPs. The synthesized nanostructure consisting of POP and FeNP could be used as a pollutant remedy because of its ability to adsorbing crude oil and it is maneuverable under an applied magnetism.

The Stability and Oxidation Resistance of Iron- and Cobalt-Based Magnetic Nanoparticle Fluids Fabricated by Inert-Gas Condensation

DTIC Science & Technology

2005-01-01

imaging, drug delivery, and hyperthermia treatment for cancer . Ideal magnetic nanoparticle fluids have well-separated, biocompatible nanoparticles with a...Based Magnetic Nanoparticle Fluids Fabricated by Inert-Gas Condensation DISTRIBUTION: Approved for public release, distribution unlimited This paper...Oxidation Resistance of Iron- and Cobalt-Based Magnetic Nanoparticle Fluids Fabricated by Inert-Gas Condensation Nguyen H. Hail, Raymond Lemoine’, Shaina

Impact of Metal and Metal Oxide Nanoparticles on Plant: A Critical Review

PubMed Central

Rastogi, Anshu; Zivcak, Marek; Sytar, Oksana; Kalaji, Hazem M.; He, Xiaolan; Mbarki, Sonia; Brestic, Marian

2017-01-01

An increasing need of nanotechnology in various industries may cause a huge environment dispersion of nanoparticles in coming years. A concern about nanoparticles interaction with flora and fauna is raised due to a growing load of it in the environment. In recent years, several investigators have shown impact of nanoparticles on plant growth and their accumulation in food source. This review examines the research performed in the last decade to show how metal and metal oxide nanoparticles are influencing the plant metabolism. We addressed here, the impact of nanoparticle on plant in relation to its size, concentration, and exposure methodology. Based on the available reports, we proposed oxidative burst as a general mechanism through which the toxic effects of nanoparticles are spread in plants. This review summarizes the current understanding and the future possibilities of plant-nanoparticle research. PMID:29075626

Peptide conjugated magnetic nanoparticles for magnetically mediated energy delivery to lung cancer cells.

PubMed

Hauser, Anastasia K; Anderson, Kimberly W; Hilt, J Zach

2016-07-01

In the present study, we examine the effects of internalized peptide-conjugated iron oxide nanoparticles and their ability to locally convert alternating magnetic field (AMF) energy into other forms of energy (e.g., heat and rotational work). Dextran-coated iron oxide nanoparticles were functionalized with a cell penetrating peptide and after internalization by A549 and H358 cells were activated by an AMF. TAT-functionalized nanoparticles and AMF exposure increased reactive oxygen species generation compared with the nanoparticle system alone. The TAT-functionalized nanoparticles induced lysosomal membrane permeability and mitochondrial membrane depolarization, but these effects were not further enhanced by AMF treatment. Although not statistically significant, there are trends suggesting an increase in apoptosis via the Caspase 3/7 pathways when cells are exposed to TAT-functionalized nanoparticles combined with AMF. Our results indicate that internalized TAT-functionalized iron oxide nanoparticles activated by an AMF elicit cellular responses without a measurable temperature rise.

Intracellular degradation of functionalized carbon nanotube/iron oxide hybrids is modulated by iron via Nrf2 pathway

PubMed Central

Elgrabli, Dan; Dachraoui, Walid; Marmier, Hélène de; Ménard-Moyon, Cécilia; Bégin, Dominique; Bégin-Colin, Sylvie; Bianco, Alberto; Alloyeau, Damien; Gazeau, Florence

2017-01-01

The in vivo fate and biodegradability of carbon nanotubes is still a matter of debate despite tremendous applications. In this paper we describe a molecular pathway by which macrophages degrade functionalized multi-walled carbon nanotubes (CNTs) designed for biomedical applications and containing, or not, iron oxide nanoparticles in their inner cavity. Electron microscopy and Raman spectroscopy show that intracellularly-induced structural damages appear more rapidly for iron-free CNTs in comparison to iron-loaded ones, suggesting a role of iron in the degradation mechanism. By comparing the molecular responses of macrophages derived from THP1 monocytes to both types of CNTs, we highlight a molecular mechanism regulated by Nrf2/Bach1 signaling pathways to induce CNT degradation via NOX2 complex activation and O2•−, H2O2 and OH• production. CNT exposure activates an oxidative stress-dependent production of iron via Nrf2 nuclear translocation, Ferritin H and Heme oxygenase 1 translation. Conversely, Bach1 was translocated to the nucleus of cells exposed to iron-loaded CNTs to recycle embedded iron. Our results provide new information on the role of oxidative stress, iron metabolism and Nrf2-mediated host defence for regulating CNT fate in macrophages. PMID:28120861

Enhanced sun protection of nano-sized metal oxide particles over conventional metal oxide particles: an in vitro comparative study.

PubMed

Singh, P; Nanda, A

2014-06-01

A systematic and detailed study has been designed and conducted, taking into account some of the proposed benefits such as increased efficiency, transparency, unique texture, protection of active ingredient and higher consumer compliance of cosmetics containing nano-sized metal oxides. This study also presents an in vitro method to determine sun protection factor of the investigational sunscreen cream samples containing zinc oxide and titanium dioxide with a varied range of particle size. Finally, a comparative study has been conducted between metal oxide particles, conventional as well as nanoparticles. All the skin cosmetics formulated were thermally stable with a pH ranging from 7.9 to 8.2. Moreover, the fatty acid substance content and residue were found to be analogous to the standard values in each skin cosmetic. The skin cosmetics containing the titanium or zinc oxide nanoparticles were found to have improved spreadability as compared to skin cosmetics containing conventional titanium or zinc oxide particles, respectively. All skin cosmetics were found to have uniform distribution of the particles. The sunscreen creams containing zinc oxide nanoparticles and titanium dioxide nanoparticles were found to have higher in vitro sun protection factor (SPF of 3.65 for ZnO nanoparticles and 4.93 for TiO2 nanoparticles) as compared to that of sunscreen creams containing conventional zinc oxide particles (SPF = 2.90) and conventional titanium dioxide (SPF = 1.29), clearly indicating the effect of reduction in particles size, from micro to nano, on the sun protection factor. Good texture, better spreadability and enhanced in vitro SPF proved the advantageous role of nanoparticles in cosmetics. © 2014 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

Iron oxide and gold nanoparticles in cancer therapy

NASA Astrophysics Data System (ADS)

Gotman, Irena; Psakhie, Sergey G.; Lozhkomoev, Aleksandr S.; Gutmanas, Elazar Y.

2016-08-01

Continuous research activities in the field of nanomedicine in the past decade have, to a great extent, been focused on nanoparticle technologies for cancer therapy. Gold and iron oxide nanoparticles (NP) are two of the most studied inorganic nanomaterials due to their unique optical and magnetic properties. Both types of NPs are emerging as promising systems for anti-tumor drug delivery and for nanoparticle-mediated thermal therapy of cancer. In thermal therapy, localized heating inside tumors or in proximity of tumor cells can be induced, for example, with Au NPs by radiofrequency ablation heating or conversion of photon energy (photothermal therapy) and in iron oxide magnetic NPs by heat generation through relaxation in an alternating magnetic field (magnetic hyperthermia). Furthermore, the superparamagnetic properties of iron oxide nanoparticles have led to their use as potent MRI (magnetic resonance imaging) contrast agents. Surface modification/coating can produce NPs with tailored and desired properties, such as enhanced blood circulation time, stability, biocompatibility and water solubility. To target nanoparticles to specific tumor cells, NPs should be conjugated with targeting moieties on the surface which bind to receptors or other molecular structures on the cell surface. The article presents several approaches to enhancing the specificity of Au and iron oxide nanoparticles for tumor tissue by appropriate surface modification/functionalization, as well as the effect of these treatments on the saturation magnetization value of iron oxide NPs. The use of other nanoparticles and nanostructures in cancer treatment is also briefly reviewed.

Structure deformation of indium oxide from nanoparticles into nanostructured polycrystalline films by in situ thermal radiation treatment

PubMed Central

2013-01-01

A microstructure deformation of indium oxide (In2O3) nanoparticles by an in situ thermal radiation treatment in nitrous oxide plasma was investigated. The In2O3 nanoparticles were completely transformed into nanostructured In2O3 films upon 10 min of treatment time. The treated In2O3 nanoparticle sample showed improvement in crystallinity while maintaining a large surface area of nanostructure morphology. The direct transition optical absorption at higher photon energy and the electrical conductivity of the In2O3 nanoparticles were significantly enhanced by the treatment. PMID:24134646

Promising iron oxide-based magnetic nanoparticles in biomedical engineering.

PubMed

Tran, Phuong Ha-Lien; Tran, Thao Truong-Dinh; Vo, Toi Van; Lee, Beom-Jin

2012-12-01

For the past few decades biomedical engineering has imprinted its significant impact on the map of science through its wide applications on many other fields. An important example obviously proving this fact is the versatile application of magnetic nanoparticles in theranostics. Due to preferable properties such as biocompatibility, non-toxicity compared to other metal derivations, iron oxide-based magnetic nanoparticles was chosen to be addressed in this review. Aim of this review is to give the readers a whole working window of these magnetic nanoparticles in the current context of science. Thus, preparation of magnetic iron oxide nanoparticles with the so-far techniques, methods of characterizing the nanoparticles as well as their most recent biomedical applications will be stated.

Dextran and Polymer Polyethylene Glycol (PEG) Coating Reduce Both 5 and 30 nm Iron Oxide Nanoparticle Cytotoxicity in 2D and 3D Cell Culture

PubMed Central

Yu, Miao; Huang, Shaohui; Yu, Kevin Jun; Clyne, Alisa Morss

2012-01-01

Superparamagnetic iron oxide nanoparticles are widely used in biomedical applications, yet questions remain regarding the effect of nanoparticle size and coating on nanoparticle cytotoxicity. In this study, porcine aortic endothelial cells were exposed to 5 and 30 nm diameter iron oxide nanoparticles coated with either the polysaccharide, dextran, or the polymer polyethylene glycol (PEG). Nanoparticle uptake, cytotoxicity, reactive oxygen species (ROS) formation, and cell morphology changes were measured. Endothelial cells took up nanoparticles of all sizes and coatings in a dose dependent manner, and intracellular nanoparticles remained clustered in cytoplasmic vacuoles. Bare nanoparticles in both sizes induced a more than 6 fold increase in cell death at the highest concentration (0.5 mg/mL) and led to significant cell elongation, whereas cell viability and morphology remained constant with coated nanoparticles. While bare 30 nm nanoparticles induced significant ROS formation, neither 5 nm nanoparticles (bare or coated) nor 30 nm coated nanoparticles changed ROS levels. Furthermore, nanoparticles were more toxic at lower concentrations when cells were cultured within 3D gels. These results indicate that both dextran and PEG coatings reduce nanoparticle cytotoxicity, however different mechanisms may be important for different size nanoparticles. PMID:22754315

Local Schottky contacts of embedded Ag nanoparticles in Al2O3/SiNx:H stacks on Si: a design to enhance field effect passivation of Si junctions.

PubMed

Ibrahim Elmi, Omar; Cristini-Robbe, Odile; Chen, Minyu; Wei, Bin; Bernard, Rémy; Okada, Etienne; Yarekha, Dmitri A; Ouendi, Saliha; Portier, Xavier; Gourbilleau, Fabrice; Xu, Tao; Stievenard, Didier

2018-04-26

This paper describes an original design leading to the field effect passivation of Si n+-p junctions. Ordered Ag nanoparticle (Ag-NP) arrays with optimal size and coverage fabricated by means of nanosphere lithography and thermal evaporation, were embedded in ultrathin-Al2O3/SiNx:H stacks on the top of implanted Si n+-p junctions, to achieve effective surface passivation. One way to characterize surface passivation is to use photocurrent, sensitive to recombination centers. We evidenced an improvement of photocurrent by a factor of 5 with the presence of Ag nanoparticles. Finite-difference time-domain (FDTD) simulations combining with semi-quantitative calculations demonstrated that such gain was mainly due to the enhanced field effect passivation through the depleted region associated with the Ag-NPs/Si Schottky contacts. © 2018 IOP Publishing Ltd.

Gentamicin coated iron oxide nanoparticles as novel antibacterial agents

NASA Astrophysics Data System (ADS)

Bhattacharya, Proma; Neogi, Sudarsan

2017-09-01

Applications of different types of magnetic nanoparticles for biomedical purposes started a long time back. The concept of surface functionalization of the iron oxide nanoparticles with antibiotics is a novel technique which paves the path for further application of these nanoparticles by virtue of their property of superparamagnetism. In this paper, we have synthesized novel iron oxide nanoparticles surface functionalized with Gentamicin. The average size of the particles, concluded from the HR-TEM images, came to be around 14 nm and 10 nm for unmodified and modified nanoparticles, respectively. The magnetization curve M(H) obtained for these nanoparticles are typical of superparamagnetic nature and having almost zero values of coercivity and remanance. The release properties of the drug coated nanoparticles were studied; obtaining an S shaped profile, indicating the initial burst effect followed by gradual sustained release. In vitro investigations against various gram positive and gram negative strains viz Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Bacillus subtilis indicated significant antibacterial efficiency of the drug-nanoparticle conjugate. The MIC values indicated that a small amount like 0.2 mg ml-1 of drug capped particles induce about 98% bacterial death. The novelty of the work lies in the drug capping of the nanoparticles, which retains the superparamagnetic nature of the iron oxide nanoparticles and the medical properties of the drug simultaneously, which is found to extremely blood compatible.

Zinc oxide nanoparticles induce rat retinal ganglion cell damage through bcl-2, caspase-9 and caspase-12 pathways.

PubMed

Guo, Dadong; Bi, Hongsheng; Wu, Qiuxin; Wang, Daoguang; Cui, Yan

2013-06-01

Nanomaterials, including zinc oxide (ZnO) nanoparticles, are being developed for a variety of commercial products. Recent reports showed that cells exposed to ZnO nanoparticles produced severe cytotoxicity accompanied by oxidative stress and genotoxicity. To understand the possible mechanism underlying oxidative stress of ZnO nanoparticles, the present investigation focused on the direct bioactivity of ZnO nanoparticles using a rat retinal ganglion cell (RGC-5) culture. At concentrations relevant to those used in vitro exposure of RGC-5 cells to ZnO nanoparticles, it was found that ZnO nanoparticles could inhibit cell proliferation in time- and concentration-dependent manners. Meanwhile, cell cycle arrest of S and G2/M phases occurred in RGC-5 cells induced by ZnO nanoparticles. Moreover, our results also demonstrated that the overproduction of reactive oxygen species (ROS) and elevated level of caspase-12 as well as decreased levels of bcl-2 and caspase-9 occurred after treatment with different concentrations of ZnO nanoparticles when compared to those in untreated cells. In summary, our findings suggest that ZnO nanoparticles could lead to the over generations of ROS and caspase-12 as well as decreased levels of bcl-2 and caspase-9. These results indicate that bcl-2, caspase-9 and caspase-12 may play significant roles in ZnO nanoparticle-induced RGC-5 cell damage.

Subsurface thermal behaviour of tissue mimics embedded with large blood vessels during plasmonic photo-thermal therapy.

PubMed

Paul, Anup; Narasimhan, Arunn; Das, Sarit K; Sengupta, Soujit; Pradeep, Thalappil

2016-11-01

The purpose of this study was to understand the subsurface thermal behaviour of a tissue phantom embedded with large blood vessels (LBVs) when exposed to near-infrared (NIR) radiation. The effect of the addition of nanoparticles to irradiated tissue on the thermal sink behaviour of LBVs was also studied. Experiments were performed on a tissue phantom embedded with a simulated blood vessel of 2.2 mm outer diameter (OD)/1.6 mm inner diameter (ID) with a blood flow rate of 10 mL/min. Type I collagen from bovine tendon and agar gel were used as tissue. Two different nanoparticles, gold mesoflowers (AuMS) and graphene nanostructures, were synthesised and characterised. Energy equations incorporating a laser source term based on multiple scattering theories were solved using finite element-based commercial software. The rise in temperature upon NIR irradiation was seen to vary according to the position of the blood vessel and presence of nanoparticles. While the maximum rise in temperature was about 10 °C for bare tissue, it was 19 °C for tissue embedded with gold nanostructures and 38 °C for graphene-embedded tissues. The axial temperature distribution predicted by computational simulation matched the experimental observations. A different subsurface temperature distribution has been obtained for different tissue vascular network models. The position of LBVs must be known in order to achieve optimal tissue necrosis. The simulation described here helps in predicting subsurface temperature distributions within tissues during plasmonic photo-thermal therapy so that the risks of damage and complications associated with in vivo experiments and therapy may be avoided.

Synthesis and characterization of nanocomposite GO@α-Fe2O3:Efficient material for dye removal

NASA Astrophysics Data System (ADS)

Mandal, B.; Panda, J.; Tudu, B.

2018-05-01

In this work a composite of Graphene Oxide (GO) supported α-Fe2O3 nanoparticles (GF) has been synthesized via a simple co-precipitation method. Structural, and morphological study of nanocomposite (GF) are examined by powder X-ray diffraction (PXRD), field emission scanning electron microscopy (FESEM) and Transmission electron microscopy (TEM). The XRD study indicates that Graphene oxide is implanted with well crystalline α-Fe2O3 which has pure rhombohedral phase. Surface morphological study of SEM depicts sphere-like shaped α-Fe2O3 particles with formation of clusters have been embedded on Graphene oxide nano sheet. TEM image reveals that GO sheet acts as a good supporting material for anchoring nano sized α -Fe2O3 particles. Efficiency of dye removal of the prepared GF composite has been measured by the degradation of methylene blue (MB) in an aqueous solution under visible light irradiation. The degradation of the dye has been evaluated by a UV-visible spectroscopy, by decrease in the intensity of absorbance and concentration. The degradation efficiency of GF is found to be 90% towards MB.

Method for producing metal oxide nanoparticles

DOEpatents

Phillips, Jonathan [Santa Fe, NM; Mendoza, Daniel [Santa Fe, NM; Chen, Chun-Ku [Albuquerque, NM

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.

Thermoelectric power factor enhancement by ionized nanoparticle scattering

NASA Astrophysics Data System (ADS)

Bahk, Je-Hyeong; Bian, Zhixi; Zebarjadi, Mona; Santhanam, Parthiban; Ram, Rajeev; Shakouri, Ali

2011-08-01

We show theoretically that the thermoelectric power factor can be enhanced in degenerate semiconductors when embedded nanoparticles donate carriers to the matrix and replace conventional impurity dopants as scattering centers. Nanoparticle scattering rates calculated by the partial wave method indicate a mobility enhancement over materials with equivalent doping by isolated ionized impurities while the Seebeck coefficient remains nearly intact. We find that the thermoelectric power factor of In0.53Ga0.47As from 300 K to 800 K is enhanced by 15% - 30% by nanoparticles 3-4 nm in diameter.

Optical studies of CdSe/HgSe and CdSe/Ag2Se core/shell nanoparticles embedded in gelatin

NASA Astrophysics Data System (ADS)

Azhniuk, Yu M.; Dzhagan, V. M.; Raevskaya, A. E.; Stroyuk, A. L.; Kuchmiy, S. Ya; Valakh, M. Ya; Zahn, D. R. T.

2008-11-01

CdSe/HgSe and CdSe/Ag2Se core-shell nanoparticles are obtained by colloidal synthesis from aqueous solutions in the presence of gelatin. Optical absorption, luminescence, and Raman spectra of the nanoparticles obtained are measured. The variation of the optical spectra of CdSe/HgSe and CdSe/Ag2Se core-shell nanoparticles with the shell thickness is discussed. Sharp non-monotonous variation of the photoluminescence spectra at low shell coverage is observed.

In situ synthesis of metal nanoparticles in polymer matrix and their optical limiting applications.

PubMed

Porel, S; Venkatram, N; Rao, D Narayana; Radhakrishnan, T P

2007-06-01

We present an overview of the simple and environmentally benign protocol we have developed recently, for the in situ generation of metal nanoparticles inside polymer films by mild thermal annealing, leading to free-standing as well as supported thin films of nanoparticle-embedded polymer. The fabrication chemistry is discussed and spectroscopic/microscopic characterizations of silver and gold nanoparticles in poly(vinyl alcohol) film are presented. Optical limiting characteristics of the silver-polymer system are investigated in detail and preliminary results for the gold-polymer system are reported.

Ion beam synthesis of Au nanoparticles embedded nano-composite glass

NASA Astrophysics Data System (ADS)

Varma, Ranjana S.; Kothari, D. C.; Kumar, Ravi; Kumar, P.; Santra, S. S.; Thomas, R. G.

2013-02-01

Ion beam mixing using low energy (LE) ion beams (100 keV Ar+) has been used to form Au nanoparticles in the near-surface region of fused silica glasses. Effect of swift heavy ion (SHI) irradiation (with 120 MeV Ag9+), on the nanoparticles has been studied. Diffusion length of Au after the beam mixing and the irradiation has been found to be 14nm. SHI irradiation causes the increase in the size of the nanoparticles, reduction in size-distribution and increase in number density.

Quantitative 3D evolution of colloidal nanoparticle oxidation in solution

DOE PAGES

Sun, Yugang; Zuo, Xiaobing; Sankaranarayanan, Subramanian K. R. S.; ...

2017-04-21

Real-time tracking three-dimensional (3D) evolution of colloidal nanoparticles in solution is essential for understanding complex mechanisms involved in nanoparticle growth and transformation. We simultaneously use time-resolved small-angle and wide-angle x-ray scattering to monitor oxidation of highly uniform colloidal iron nanoparticles, enabling the reconstruction of intermediate 3D morphologies of the nanoparticles with a spatial resolution of ~5 Å. The in-situ probing combined with large-scale reactive molecular dynamics simulations reveals the transformational details from the solid metal nanoparticles to hollow metal oxide nanoshells via nanoscale Kirkendall process, for example, coalescence of voids upon their growth, reversing of mass diffusion direction depending onmore » crystallinity, and so forth. In conclusion, our results highlight the complex interplay between defect chemistry and defect dynamics in determining nanoparticle transformation and formation.« less

Quantitative 3D evolution of colloidal nanoparticle oxidation in solution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Yugang; Zuo, Xiaobing; Sankaranarayanan, Subramanian K. R. S.

Real-time tracking three-dimensional (3D) evolution of colloidal nanoparticles in solution is essential for understanding complex mechanisms involved in nanoparticle growth and transformation. We simultaneously use time-resolved small-angle and wide-angle x-ray scattering to monitor oxidation of highly uniform colloidal iron nanoparticles, enabling the reconstruction of intermediate 3D morphologies of the nanoparticles with a spatial resolution of ~5 Å. The in-situ probing combined with large-scale reactive molecular dynamics simulations reveals the transformational details from the solid metal nanoparticles to hollow metal oxide nanoshells via nanoscale Kirkendall process, for example, coalescence of voids upon their growth, reversing of mass diffusion direction depending onmore » crystallinity, and so forth. In conclusion, our results highlight the complex interplay between defect chemistry and defect dynamics in determining nanoparticle transformation and formation.« less

Electron-hole pairs generated in ZrO2 nanoparticle resist upon exposure to extreme ultraviolet radiation

NASA Astrophysics Data System (ADS)

Kozawa, Takahiro; Santillan, Julius Joseph; Itani, Toshiro

2018-02-01

Metal oxide nanoparticle resists have attracted much attention as the next-generation resist used for the high-volume production of semiconductor devices. However, the sensitization mechanism of the metal oxide nanoparticle resists is unknown. Understanding the sensitization mechanism is important for the efficient development of resist materials. In this study, the energy deposition in a zirconium oxide (ZrO2) nanoparticle resist was investigated. The numbers of electron-hole pairs generated in a ZrO2 core and an methacrylic acid (MAA) ligand shell upon exposure to 1 mJ cm-2 (exposure dose) extreme ultraviolet (EUV) radiations were theoretically estimated to be 0.16 at most and 0.04-0.17 cm2 mJ-1, respectively. By comparing the calculated distribution of electron-hole pairs with the line-and-space patterns of the ZrO2 nanoparticle resist fabricated by an EUV exposure tool, the number of electron-hole pairs required for the solubility change of the resist films was estimated to be 1.3-2.2 per NP. NP denotes a nanoparticle consisting of a metal oxide core with a ligand shell. In the material design of metal oxide nanoparticle resists, it is important to efficiently use the electron-hole pairs generated in the metal oxide core for the chemical change of ligand molecules.

Rational Design and Development of Reactive Multifunctional Micellar Composite Nano-particles for Destruction of Bio-agents

DTIC Science & Technology

2015-02-01

nanoparticles, , multifunction porous metal oxide -silica composites, porous silicon - Titania and PSi-silver heterojunctions ) have been successfully...nanoparticles, multifunctional porous metal oxide -silica composites, porous silicon -Titania and PSi-silver heterojunctions ) have been successfully...generated charge separation and enhance the photocatalytic oxidation . In the PSi-Ag heterojunctions , Ag can not only act as time-honored antibacterial

Semiconductor-Based Nanotechnology Applications

DTIC Science & Technology

2012-11-07

Nanotechnology Organization Conference, November 4-6, 2012 at the Hilton Arlington, VA 4. Selective toxicity of zinc oxide nanoparticles to cancer...surface structure of oxide nanoparticles , we have recently shown that both magnetic and photoluminescence properties can be tailored. ZnO nanoparticles ...as SnO2, ZnO , and CeO2, reported in 40 refereed research papers. In this ARO project, studies on ultra small particles of these oxides with

Chemical synthesis and characterization of hollow dopamine coated, pentagonal and flower shaped magnetic iron oxide nanoparticles

NASA Astrophysics Data System (ADS)

Riasat, Rabia; Kaynat, Sumbal

2018-04-01

Iron oxide nanoparticles have gained attention recently in the field of nanoscience and technology due to their unique physicochemical properties. We hereby chemically synthesized novel pentagonal flower shaped iron oxide nanoparticles by thermal decomposition of iron penta-carbonyl in a two way annealing process. Controlled oxidation by acid etching was performed for these nanoparticles. At first 13 nm core shell nanoparticles of iron oxide (Fe/Fe3O4) were synthesized at 120°C annealing temperature that act as template material. The core shell nanoparticles then converted into porous hollow core shell nanoparticles (PH Fe/ Fe3O4) in a two way annealing process of heating, first at 100°C then at 250°C and heating rate of 5°C was kept constant throughout the reaction time. X-Ray diffraction (XRD) was done for the phase confirmation of as synthesized nanoparticles. Transmission electron microscopy (TEM) and higher resolution transmission electron microscopy (HRTEM) clearly shows the flower like nanoparticles that are approx. 16 nm-18 nm in size having the 4-5 nm core of Fe and 1-2 nm of the pores in the shell while the cavity between the shell and core is about 2 nm and the shell is 4-5 nm in diameter according to the TEM micrographs. The as prepared nanoparticles were then surface functionalized by dopamine polymer to make them water dispersible. Fourier transform Infrared spectroscopy confirmed the dopamine coating on the nanoparticles and the magnetic saturation of 38 emu/g of nanoparticles was analyzed by vibrating sample magnetometer (VSM). Magnetic saturation persists in the dopamine coated nanoparticles. These nanoparticles were surface functionalized with dopamine and show dispersity in the aqueous media and can further be exploited in many nano-biotechnological applications including target specific therapeutic applications for several diseases.

In situ growth of capping-free magnetic iron oxide nanoparticles on liquid-phase exfoliated graphene

NASA Astrophysics Data System (ADS)

Tsoufis, T.; Syrgiannis, Z.; Akhtar, N.; Prato, M.; Katsaros, F.; Sideratou, Z.; Kouloumpis, A.; Gournis, D.; Rudolf, P.

2015-05-01

We report a facile approach for the in situ synthesis of very small iron oxide nanoparticles on the surface of high-quality graphene sheets. Our synthetic strategy involved the direct, liquid-phase exfoliation of highly crystalline graphite (avoiding any oxidation treatment) and the subsequent chemical functionalization of the graphene sheets via the well-established 1,3-dipolar cycloaddition reaction. The resulting graphene derivatives were employed for the immobilization of the nanoparticle precursor (Fe cations) at the introduced organic groups by a modified wet-impregnation method, followed by interaction with acetic acid vapours. The final graphene-iron oxide hybrid material was achieved by heating (calcination) in an inert atmosphere. Characterization by X-ray diffraction, transmission electron and atomic force microscopy, Raman and X-ray photoelectron spectroscopy gave evidence for the formation of rather small (<12 nm), spherical, magnetite-rich nanoparticles which were evenly distributed on the surface of few-layer (<1.2 nm thick) graphene. Due to the presence of the iron oxide nanoparticles, the hybrid material showed a superparamagnetic behaviour at room temperature.We report a facile approach for the in situ synthesis of very small iron oxide nanoparticles on the surface of high-quality graphene sheets. Our synthetic strategy involved the direct, liquid-phase exfoliation of highly crystalline graphite (avoiding any oxidation treatment) and the subsequent chemical functionalization of the graphene sheets via the well-established 1,3-dipolar cycloaddition reaction. The resulting graphene derivatives were employed for the immobilization of the nanoparticle precursor (Fe cations) at the introduced organic groups by a modified wet-impregnation method, followed by interaction with acetic acid vapours. The final graphene-iron oxide hybrid material was achieved by heating (calcination) in an inert atmosphere. Characterization by X-ray diffraction, transmission electron and atomic force microscopy, Raman and X-ray photoelectron spectroscopy gave evidence for the formation of rather small (<12 nm), spherical, magnetite-rich nanoparticles which were evenly distributed on the surface of few-layer (<1.2 nm thick) graphene. Due to the presence of the iron oxide nanoparticles, the hybrid material showed a superparamagnetic behaviour at room temperature. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr00765h

Morphology and electronic structure of the oxide shell on the surface of iron nanoparticles.

PubMed

Wang, Chongmin; Baer, Donald R; Amonette, James E; Engelhard, Mark H; Antony, Jiji; Qiang, You

2009-07-01

An iron (Fe) nanoparticle exposed to air at room temperature will be instantly covered by an oxide shell that is typically approximately 3 nm thick. The nature of this native oxide shell, in combination with the underlying Fe(0) core, determines the physical and chemical behavior of the core-shell nanoparticle. One of the challenges of characterizing core-shell nanoparticles is determining the structure of the oxide shell, that is, whether it is FeO, Fe(3)O(4), gamma-Fe(2)O(3), alpha-Fe(2)O(3), or something else. The results of prior characterization efforts, which have mostly used X-ray diffraction and spectroscopy, electron diffraction, and transmission electron microscopic imaging, have been framed in terms of one of the known Fe-oxide structures, although it is not necessarily true that the thin layer of Fe oxide is a known Fe oxide. In this Article, we probe the structure of the oxide shell on Fe nanoparticles using electron energy loss spectroscopy (EELS) at the oxygen (O) K-edge with a spatial resolution of several nanometers (i.e., less than that of an individual particle). We studied two types of representative particles: small particles that are fully oxidized (no Fe(0) core) and larger core-shell particles that possess an Fe core. We found that O K-edge spectra collected for the oxide shell in nanoparticles show distinct differences from those of known Fe oxides. Typically, the prepeak of the spectra collected on both the core-shell and the fully oxidized particles is weaker than that collected on standard Fe(3)O(4). Given the fact that the origin of this prepeak corresponds to the transition of the O 1s electron to the unoccupied state of O 2p hybridized with Fe 3d, a weak pre-edge peak indicates a combination of the following four factors: a higher degree of occupancy of the Fe 3d orbital; a longer Fe-O bond length; a decreased covalency of the Fe-O bond; and a measure of cation vacancies. These results suggest that the coordination configuration in the oxide shell on Fe nanoparticles is defective as compared to that of their bulk counterparts. Implications of these defective structural characteristics on the properties of core-shell structured iron nanoparticles are discussed.

Different effect of hydrogelation on anti-fouling and circulation properties of dextran–iron oxide nanoparticles

PubMed Central

Karmali, Priya Prakash; Chao, Ying; Park, Ji-Ho (Joe); Sailor, Michael J.; Ruoslahti, Erkki; Esener, Sadik C.; Simberg, Dmitri

2012-01-01

Premature recognition and clearance of nanoparticulate imaging and therapeutic agents by macrophages in the tissues can dramatically reduce both the nanoparticle half-life and delivery to the diseased tissue. Grafting nanoparticles with hydrogels prevents nanoparticulate recognition by liver and spleen macrophages and greatly prolongs circulation times in vivo. Understanding the mechanisms by which hydrogels achieve this “stealth” effect has implications for the design of long-circulating nanoparticles. Thus, the role of plasma protein absorption in the hydrogel effect is not yet understood. Short-circulating dextran-coated iron oxide nanoparticles could be converted into stealth hydrogel nanoparticles by crosslinking with 1-chloro-2,3-epoxypropane. We show that hydrogelation did not affect the size, shape and zeta potential, but completely prevented the recognition and clearance by liver macrophages in vivo. Hydrogelation decreased the number of hydroxyl groups on the nanoparticle surface and reduced the binding of the anti-dextran antibody. At the same time, hydrogelation did not reduce the absorption of cationic proteins on the nanoparticle surface. Specifically, there was no effect on the binding of kininogen, histidine-rich glycoprotein, and protamine sulfate to the anionic nanoparticle surface. In addition, hydrogelation did not prevent activation of plasma kallikrein on the metal oxide surface. These data suggest that: (a) a stealth hydrogel coating does not mask charge interactions with iron oxide surface and (b) the total blockade of plasma protein absorption is not required for maintaining iron oxide nanoparticles’ long-circulating stealth properties. These data illustrate a novel, clinically promising property of long-circulating stealth nanoparticles. PMID:22243419

Two-Solvent Method Synthesis of NiO/ZnO Nanoparticles Embedded in Mesoporous SBA-15: Photocatalytic Properties Study.

PubMed

Dai, Peng; Yan, Tao-Tao; Yu, Xin-Xin; Bai, Zhi-Man; Wu, Ming-Zai

2016-12-01

Different loadings of NiO/ZnO nanoparticles embedded in mesoporous silica (SBA-15) were prepared via a two-solvent method with the ordered hexagonal mesoporous structure of SBA-15 kept. X-ray diffraction, transmission electron microscope, X-ray photoelectron spectroscopy, diffusive reflective UV-vis spectroscopy, and N2 adsorption porosimetry were employed to characterize the nanocomposites. The results indicate that the ordered hexagonal mesoporous structure of SBA-15 is kept and the absorption band edges of the nanocomposites shift into the ultraviolet light regime. The photocatalytic activity of our samples for degradation of methylene orange was investigated under UV light irradiation, and the results show that the nanocomposites have higher photodegradation ability toward methylene orange than commercial pure P-25. The photocatalytic activity of the nanocomposites was found to be dependent on both the adsorption ability of the SBA-15 and the photocatalytic activity of NiO-ZnO nanoparticles encapsulated in SBA-15. In addition, there is an optimal loading of NiO-ZnO nanoparticles. Too high or low loading will lower the photodegradation ability of the nanocomposites.

Characterization of Silicon Nanoparticles Formed from a Fluidized Bed Reactor and Their Incorporation onto Metal-Coated Carbon Fibers

NASA Astrophysics Data System (ADS)

Zbib, Mohamad B.; Sahaym, Uttara; Bahr, David F.

2014-01-01

Enhancing the light trapping using nonwoven arrays of fibers has the potential to improve the photocurrent of silicon solar cells. In this work, amorphous and crystalline Si nanopowders (30-300 nm) were embedded in carbon fibers and fixed in place with electrodeposited nickel. Scanning and transmission electron microscopy techniques have been used to study the morphology of the Si particles and their interactions with the coatings. Two types of nanoparticles are identified, homogeneous nucleated particles (amorphous particles with some crystalline regions) and attrition particles (mostly crystalline products formed from fracture of particles as they grow in a fluidized bed reactor). Using the Brunauer-Emmett-Teller (BET) technique, the surface area and the pore diameter of these agglomerated Si nanoparticles were calculated to be 6.4 m2/g and 9.8 nm, respectively. After embedding the Si particles into the carbon matrix with the metal coatings, the electrical resistivity decreases, suggesting it is possible to enhance the light extraction of silicon solar cells using Si nanoparticles.

CuO nanoparticles encapsulated inside Al-MCM-41 mesoporous materials via direct synthetic route

PubMed Central

Huo, Chengli; Ouyang, Jing; Yang, Huaming

2014-01-01

Highly ordered aluminum-containing mesoporous silica (Al-MCM-41) was prepared using attapulgite clay mineral as a Si and Al source. Mesoporous complexes embedded with CuO nanoparticles were subsequently prepared using various copper sources and different copper loadings in a direct synthetic route. The resulting CuO/Al-MCM-41 composite possessed p6mm hexagonally symmetry, well-developed mesoporosity, and relatively high BET surface area. In comparison to pure silica, these mesoporous materials embedded with CuO nanoparticles exhibited smaller pore diameter, thicker pore wall, and enhanced thermal stability. Long-range order in the aforementioned samples was observed for copper weight percentages as high as 30%. Furthermore, a significant blue shift of the absorption edge for the samples was observed when compared with that of bulk CuO. H2-TPR measurements showed that the direct-synthesized CuO/Al-MCM-41 exhibited remarkable redox properties compared to the post-synthesized samples, and most of the CuO nanoparticles were encapsulated within the mesoporous structures. The possible interaction between CuO and Al-MCM-41 was also investigated. PMID:24419589

Interfacial surfactant competition and its impact on poly(ethylene oxide)/Au and poly(ethylene oxide)/Ag nanocomposite properties

PubMed Central

Seyhan, Merve; Kucharczyk, William; Yarar, U Ecem; Rickard, Katherine; Rende, Deniz; Baysal, Nihat; Bucak, Seyda; Ozisik, Rahmi

2017-01-01

The structure and properties of nanocomposites of poly(ethylene oxide), with Ag and Au nanoparticles, surface modified with a 1:1 (by volume) oleylamine/oleic acid mixture, were investigated via transmission electron microscopy, scanning electron microscopy, thermogravimetric analysis, differential scanning calorimetry (DSC), infrared spectroscopy, dynamic mechanical analysis, and static mechanical testing. Results indicated that there was more oleylamine on Ag nanoparticles but more oleic acid on Au nanoparticles. This difference in surfactant populations on each nanoparticle led to different interfacial interactions with poly(ethylene oxide) and drastically influenced the glass transition temperature of these two nanocomposite systems. Almost all other properties were found to correlate strongly with dispersion and distribution state of Au and Ag nanoparticles, such that the property in question changed direction at the onset of agglomeration. PMID:28461744

Oxidative stress mediated apoptosis induced by nickel ferrite nanoparticles in cultured A549 cells.

PubMed

Ahamed, Maqusood; Akhtar, Mohd Javed; Siddiqui, Maqsood A; Ahmad, Javed; Musarrat, Javed; Al-Khedhairy, Abdulaziz A; AlSalhi, Mohamad S; Alrokayan, Salman A

2011-05-10

Due to the interesting magnetic and electrical properties with good chemical and thermal stabilities, nickel ferrite nanoparticles are being utilized in many applications including magnetic resonance imaging, drug delivery and hyperthermia. Recent studies have shown that nickel ferrite nanoparticles produce cytotoxicity in mammalian cells. However, there is very limited information concerning the toxicity of nickel ferrite nanoparticles at the cellular and molecular level. The aim of this study was to investigate the cytotoxicity, oxidative stress and apoptosis induction by well-characterized nickel ferrite nanoparticles (size 26 nm) in human lung epithelial (A549) cells. Nickel ferrite nanoparticles induced dose-dependent cytotoxicity in A549 cells demonstrated by MTT, NRU and LDH assays. Nickel ferrite nanoparticles were also found to induce oxidative stress evidenced by generation of reactive oxygen species (ROS) and depletion of antioxidant glutathione (GSH). Further, co-treatment with the antioxidant L-ascorbic acid mitigated the ROS generation and GSH depletion due to nickel ferrite nanoparticles suggesting the potential mechanism of oxidative stress. Quantitative real-time PCR analysis demonstrated that following the exposure of A549 cells to nickel ferrite nanoparticles, the level of mRNA expressions of cell cycle checkpoint protein p53 and apoptotic proteins (bax, caspase-3 and caspase-9) were significantly up-regulated, whereas the expression of anti-apoptotic proteins (survivin and bcl-2) were down-regulated. Moreover, activities of caspase-3 and caspase-9 enzymes were also significantly higher in nickel ferrite nanoparticles exposed cells. To the best of our knowledge this is the first report showing that nickel ferrite nanoparticles induced apoptosis in A549 cells through ROS generation and oxidative stress via p53, survivin, bax/bcl-2 and caspase pathways. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Palladium and Platinum Nanoparticles Attenuate Aging-Like Skin Atrophy via Antioxidant Activity in Mice

PubMed Central

Shibuya, Shuichi; Ozawa, Yusuke; Watanabe, Kenji; Izuo, Naotaka; Toda, Toshihiko; Yokote, Koutaro; Shimizu, Takahiko

2014-01-01

Cu-Zn superoxide dismutase (Sod1) loss causes a redox imbalance as it leads to excess superoxide generation, which results in the appearance of various aging-related phenotypes, including skin atrophy. Noble metal nanoparticles, such as palladium (Pd) and platinum (Pt) nanoparticles, are considered to function as antioxidants due to their strong catalytic activity. In Japan, a mixture of Pd and Pt nanoparticles called PAPLAL has been used to treat chronic diseases over the past 60 years. In the present study, we investigated the protective effects of PAPLAL against aging-related skin pathologies in mice. Transdermal PAPLAL treatment reversed skin thinning associated with increased lipid peroxidation in Sod1 −/− mice. Furthermore, PAPLAL normalized the gene expression levels of Col1a1, Mmp2, Has2, Tnf-α, Il-6, and p53 in the skin of the Sod1 −/− mice. Pt nanoparticles exhibited marked SOD and catalase activity, while Pd nanoparticles only displayed weak SOD and catalase activity in vitro. Although the SOD and catalase activity of the Pt nanoparticles significantly declined after they had been oxidized in air, a mixture of Pd and Pt nanoparticles continued to exhibit SOD and catalase activity after oxidation. Importantly, a mixture of Pd and Pt nanoparticles with a molar ratio of 3 or 4 to 1 continued to exhibit SOD and catalase activity after oxidation, indicating that Pd nanoparticles prevent the oxidative deterioration of Pt nanoparticles. These findings indicate that PAPLAL stably suppresses intrinsic superoxide generation both in vivo and in vitro via SOD and catalase activity. PAPLAL is a potentially powerful tool for the treatment of aging-related skin diseases caused by oxidative damage. PMID:25333617

Palladium and platinum nanoparticles attenuate aging-like skin atrophy via antioxidant activity in mice.

PubMed

Shibuya, Shuichi; Ozawa, Yusuke; Watanabe, Kenji; Izuo, Naotaka; Toda, Toshihiko; Yokote, Koutaro; Shimizu, Takahiko

2014-01-01

Cu-Zn superoxide dismutase (Sod1) loss causes a redox imbalance as it leads to excess superoxide generation, which results in the appearance of various aging-related phenotypes, including skin atrophy. Noble metal nanoparticles, such as palladium (Pd) and platinum (Pt) nanoparticles, are considered to function as antioxidants due to their strong catalytic activity. In Japan, a mixture of Pd and Pt nanoparticles called PAPLAL has been used to treat chronic diseases over the past 60 years. In the present study, we investigated the protective effects of PAPLAL against aging-related skin pathologies in mice. Transdermal PAPLAL treatment reversed skin thinning associated with increased lipid peroxidation in Sod1-/- mice. Furthermore, PAPLAL normalized the gene expression levels of Col1a1, Mmp2, Has2, Tnf-α, Il-6, and p53 in the skin of the Sod1-/- mice. Pt nanoparticles exhibited marked SOD and catalase activity, while Pd nanoparticles only displayed weak SOD and catalase activity in vitro. Although the SOD and catalase activity of the Pt nanoparticles significantly declined after they had been oxidized in air, a mixture of Pd and Pt nanoparticles continued to exhibit SOD and catalase activity after oxidation. Importantly, a mixture of Pd and Pt nanoparticles with a molar ratio of 3 or 4 to 1 continued to exhibit SOD and catalase activity after oxidation, indicating that Pd nanoparticles prevent the oxidative deterioration of Pt nanoparticles. These findings indicate that PAPLAL stably suppresses intrinsic superoxide generation both in vivo and in vitro via SOD and catalase activity. PAPLAL is a potentially powerful tool for the treatment of aging-related skin diseases caused by oxidative damage.

Environmental release of core–shell semiconductor nanocrystals from free-standing polymer nanocomposite films†

PubMed Central

Pillai, Karthik V.; Gray, Patrick J.; Tien, Chun-Chieh; Bleher, Reiner; Sung, Li-Piin

2016-01-01

Concomitant with the development of polymer nanocomposite (PNC) technologies across numerous industries is an expanding awareness of the uncertainty with which engineered nanoparticles embedded within these materials may be released into the external environment, particularly liquid media. Recently there has been an interest in evaluating potential exposure to nanoscale fillers from PNCs, but existing studies often rely upon uncharacterized, poor quality, or proprietary materials, creating a barrier to making general mechanistic conclusions about release phenomena. In this study we employed semiconductor nanoparticles (quantum dots, QDs) as model nanofillers to quantify potential release into liquid media under specific environmental conditions. QDs of two sizes were incorporated into low-density polyethylene by melt compounding and the mixtures were extruded as free-standing fluorescent films. These films were subjected to tests under conditions intended to accelerate potential release of embedded particles or dissolved residuals into liquid environments. Using inductively-coupled plasma mass spectrometry and laser scanning confocal microscopy, it was found that the acidity of the external medium, exposure time, and small differences in particle size (on the order of a few nm) all play pivotal roles in release kinetics. Particle dissolution was found to play a major if not dominant role in the release process. This paper also presents the first evidence that internally embedded nanoparticles contribute to the mass transfer, an observation made possible via the use of a model system that was deliberately designed to probe the complex relationships between nanoparticle-enabled plastics and the environment. PMID:27529026

Zinc Oxide Nanoparticles for Selective Destruction of Tumor Cells and Potential for Drug Delivery Applications

PubMed Central

Rasmussen, John W.; Martinez, Ezequiel; Louka, Panagiota; Wingett, Denise G.

2010-01-01

Importance of the field Metal oxide nanoparticles, including zinc oxide, are versatile platforms for biomedical applications and therapeutic intervention. There is an urgent need to develop new classes of anticancer agents, and recent studies demonstrate that ZnO nanomaterials hold considerable promise. Areas covered in this review This review analyzes the biomedical applications of metal oxide and ZnO nanomaterials under development at the experimental, preclinical, and clinical levels. A discussion regarding the advantages, approaches, and limitations surrounding the use of metal oxide nanoparticles for cancer applications and drug delivery is presented. The scope of this article is focused on ZnO, and other metal oxide nanomaterial systems, and their proposed mechanisms of cytotoxic action, as well as current approaches to improve their targeting and cytotoxicity against cancer cells. Take home message Through a better understanding of the mechanisms of action and cellular consequences resulting from nanoparticles interactions with cells, the inherent toxicity and selectivity of ZnO nanoparticles against cancer may be further improved to make them attractive new anti-cancer agents. PMID:20716019

Evaluation of folate conjugated superparamagnetic iron oxide nanoparticles for scintigraphic/magnetic resonance imaging.

PubMed

Chauhan, Ram Prakash; Mathur, Rashi; Singh, Gurjaspreet; Kaul, Ankur; Bag, Narmada; Singh, Sweta; Kumar, Hemanth; Patra, Manoj; Mishra, Anil K

2013-03-01

The physical and chemical properties of the nanoparticles influence their pharmacokinetics and ability to accumulate in tumors. In this paper we report a facile method to conjugate folic acid molecule to iron oxide nanoparticles to increase the specific uptake of these nanoparticles by the tumor, which will be useful in targeted imaging of the tumor. The iron oxide nanoparticles were synthesized by alkaline co precipitation method and were surface modified with dextranto make them stable. The folic acid is conjugated to the dextran modified iron oxide nanoparticles by reductive amination process after the oxidation of the dextran with periodate. The synthesized folic acid conjugated nanoparticles were characterized for size, phase, morphology and magnetization by using various physicochemical characterization techniques such as transmission electron microscopy, X-ray diffraction, fourier transform infrared spectroscopy, vibrating sample magnetometry, dynamic light scattering and zetasizer etc. The quantification of the generated carbonyl groups and folic acid conjugated to the surface of the magnetic nanoparticles was done by colorimetric estimations using UV-Visible spectroscopy. The in vitro MR studies were carried out over a range of concentrations and showed significant shortening of the transverse relaxation rate, showing the ability of the nanoconjugate to act as an efficient probe for MR imaging. The biodistribution studies and the scintigraphy done by radiolabeling the nanoconjugate with 99mTc show the enhanced uptake at the tumor site showing its enhanced specificity.

Dual-mode T1 and T2 magnetic resonance imaging contrast agent based on ultrasmall mixed gadolinium-dysprosium oxide nanoparticles: synthesis, characterization, and in vivo application

NASA Astrophysics Data System (ADS)

Tegafaw, Tirusew; Xu, Wenlong; Wasi Ahmad, Md; Baeck, Jong Su; Chang, Yongmin; Bae, Ji Eun; Chae, Kwon Seok; Kim, Tae Jeong; Lee, Gang Ho

2015-09-01

A new type of dual-mode T1 and T2 magnetic resonance imaging (MRI) contrast agent based on mixed lanthanide oxide nanoparticles was synthesized. Gd3+ (8S7/2) plays an important role in T1 MRI contrast agents because of its large electron spin magnetic moment resulting from its seven unpaired 4f-electrons, and Dy3+ (6H15/2) has the potential to be used in T2 MRI contrast agents because of its very large total electron magnetic moment: among lanthanide oxide nanoparticles, Dy2O3 nanoparticles have the largest magnetic moments at room temperature. Using these properties of Gd3+ and Dy3+ and their oxide nanoparticles, ultrasmall mixed gadolinium-dysprosium oxide (GDO) nanoparticles were synthesized and their potential to act as a dual-mode T1 and T2 MRI contrast agent was investigated in vitro and in vivo. The D-glucuronic acid coated GDO nanoparticles (davg = 1.0 nm) showed large r1 and r2 values (r2/r1 ≈ 6.6) and as a result clear dose-dependent contrast enhancements in R1 and R2 map images. Finally, the dual-mode imaging capability of the nanoparticles was confirmed by obtaining in vivo T1 and T2 MR images.

Study of iron oxide nanoparticles in soil for remediation of arsenic

NASA Astrophysics Data System (ADS)

Shipley, Heather J.; Engates, Karen E.; Guettner, Allison M.

2011-06-01

There is a growing interest in the use of nanoparticles for environmental applications due to their unique physical and chemical properties. One possible application is the removal of contaminants from water. In this study, the use of iron oxide nanoparticles (19.3 nm magnetite and 37.0 nm hematite) were examined to remove arsenate and arsenite through column studies. The columns contained 1.5 or 15 wt% iron oxide nanoparticles and soil. Arsenic experiments were conducted with 1.5 wt% iron oxides at 1.5 and 6 mL/h with initial arsenate and arsenite concentrations of 100 μg/L. Arsenic release occurred after 400 PV, and 100% release was reached. A long-term study was conducted with 15 wt% magnetite nanoparticles in soil at 0.3 mL/h with an initial arsenate concentration of 100 μg/L. A negligible arsenate concentration occurred for 3559.6 pore volumes (PVs) (132.1 d). Eventually, the arsenate concentration reached about 20% after 9884.1 PV (207.9 d). A retardation factor of about 6742 was calculated indicating strong adsorption of arsenic to the magnetite nanoparticles in the column. Also, increased adsorption was observed after flow interruption. Other experiments showed that arsenic and 12 other metals (V, Cr, Co, Mn, Se, Mo, Cd, Pb, Sb, Tl, Th, U) could be simultaneously removed by the iron oxide nanoparticles in soil. Effluent concentrations were less than 10% for six out of the 12 metals. Desorption experiment showed partial irreversible sorption of arsenic to the iron oxide nanoparticle surface. Strong adsorption, large retardation factor, and resistant desorption suggest that magnetite and hematite nanoparticles have the potential to be used to remove arsenic in sandy soil possibly through in situ techniques.

Platinum nanoparticles on gallium nitride surfaces: effect of semiconductor doping on nanoparticle reactivity.

PubMed

Schäfer, Susanne; Wyrzgol, Sonja A; Caterino, Roberta; Jentys, Andreas; Schoell, Sebastian J; Hävecker, Michael; Knop-Gericke, Axel; Lercher, Johannes A; Sharp, Ian D; Stutzmann, Martin

2012-08-01

Platinum nanoparticles supported on n- and p-type gallium nitride (GaN) are investigated as novel hybrid systems for the electronic control of catalytic activity via electronic interactions with the semiconductor support. In situ oxidation and reduction were studied with high pressure photoemission spectroscopy. The experiments revealed that the underlying wide-band-gap semiconductor has a large influence on the chemical composition and oxygen affinity of supported nanoparticles under X-ray irradiation. For as-deposited Pt cuboctahedra supported on n-type GaN, a higher fraction of oxidized surface atoms was observed compared to cuboctahedral particles supported on p-type GaN. Under an oxygen atmosphere, immediate oxidation was recorded for nanoparticles on n-type GaN, whereas little oxidation was observed for nanoparticles on p-type GaN. Together, these results indicate that changes in the Pt chemical state under X-ray irradiation depend on the type of GaN doping. The strong interaction between the nanoparticles and the support is consistent with charge transfer of X-ray photogenerated free carriers at the semiconductor-nanoparticle interface and suggests that GaN is a promising wide-band-gap support material for photocatalysis and electronic control of catalysis.

Magnetic Nanoparticles for Cancer Diagnosis and Therapy

PubMed Central

Yigit, Mehmet V.; Moore, Anna

2013-01-01

Nanotechnology is evolving as a new field that has a potentially high research and clinical impact. Medicine, in particular, could benefit from nanotechnology, due to emerging applications for noninvasive imaging and therapy. One important nanotechnological platform that has shown promise includes the so-called iron oxide nanoparticles. With specific relevance to cancer therapy, iron oxide nanoparticle-based therapy represents an important alternative to conventional chemotherapy, radiation, or surgery. Iron oxide nanoparticles are usually composed of three main components: an iron core, a polymer coating, and functional moieties. The biodegradable iron core can be designed to be superparamagnetic. This is particularly important, if the nanoparticles are to be used as a contrast agent for noninvasive magnetic resonance imaging (MRI). Surrounding the iron core is generally a polymer coating, which not only serves as a protective layer but also is a very important component for transforming nanoparticles into biomedical nanotools for in vivo applications. Finally, different moieties attached to the coating serve as targeting macromolecules, therapeutics payloads, or additional imaging tags. Despite the development of several nanoparticles for biomedical applications, we believe that iron oxide nanoparticles are still the most promising platform that can transform nanotechnology into a conventional medical discipline. PMID:22274558

Study of bactericidal properties of carbohydrate-stabilized platinum oxide nanoparticles

NASA Astrophysics Data System (ADS)

Rezaei-Zarchi, Saeed; Imani, Saber; mohammad Zand, Ali; Saadati, Mojtaba; Zaghari, Zahra

2012-09-01

Platinum oxide nanoparticles were prepared by a simple hydrothermal route and chemical reduction using carbohydrates (fructose and sucrose) as the reducing and stabilizing agents. In comparison with other metals, platinum oxide has less environmental pollution. Therefore, Pt is considered an appropriate candidate to deal with environmental pathogens. The crystallite size of these nanoparticles was evaluated from X-ray diffraction, atomic force microscopy, and transmission electron microscopy (TEM) and was found to be 10 nm, which is the demonstration of EM bright field and transmission electron microscopy. The effect of carbohydrates on the morphology of the nanoparticles was studied using TEM. The nanoparticles were administered to the Pseudomonas stutzeri and Lactobacillus cultures, and the incubation was done at 37°C for 24 h. The nanocomposites exhibited interesting inhibitory as well as bactericidal activity against P. stutzeri and Lactobacillus species. Incorporation of nanoparticles also increased the thermal stability of the carbohydrates. The results of this paper showed that carbohydrates can serve as a carrier for platinum oxide nanoparticles, and nanocomposites can have potential biological applications.

Chemiluminescent Diagnostics of Free-Radical Processes in an Abiotic System and in Liver Cells in the Presence of Nanoparticles Based on Rare-Earth Elements nReVO4:Eu3+ (Re = Gd, Y, La) and CeO2

NASA Astrophysics Data System (ADS)

Averchenko, E. A.; Kavok, N. S.; Klochkov, V. K.; Malyukin, Yu. V.

2014-11-01

We have used luminol-dependent chemiluminescence with Fenton's reagent to study the effect of nanoparticles based on rare-earth elements of different sizes and shapes on free-radical processes in abiotic and biotic cell-free systems, and also in isolated cells in vitro. We have estimated the effects of rare-earth orthovanadate nanoparticles of spherical (GdYVO4:Eu3+, 1-2 nm), spindle-shaped (GdVO4:Eu3+, 25 ×8 nm), and rod-shaped (LaVO4:Eu3+, 57 × (6-8) nm) nanoparticles and spherical CeO2 nanoparticles (sizes 1-2 nm and 8-10 nm). We have shown that in contrast to the abiotic system, in which all types of nanoparticles exhibit antiradical activity, in the presence of biological material, extra-small spherical (1-2 nm) nanoparticles of both types exhibit pro-oxidant activity, and also enhance pro-oxidant induced oxidative stress (for the pro-oxidants hydrogen peroxide and tert-butyl hydroperoxide). The effect of rare-earth orthovanadate spindle and rod shaped nanoparticles in this system was neutral; a moderate antioxidant effect was exhibited by 8-10 nm CeO2 nanoparticles.

Evaluation of the sonosensitizing properties of nano-graphene oxide in comparison with iron oxide and gold nanoparticles

NASA Astrophysics Data System (ADS)

Beik, Jaber; Abed, Ziaeddin; Shakeri-Zadeh, Ali; Nourbakhsh, Mitra; Shiran, Mohammad Bagher

2016-07-01

In cancer hyperthermia, ultrasound is considered as an appropriate source of energy to achieve desired therapeutic levels of heating. It is assumed that such a heating is targeted to cancer cells by using nanoparticles as sonosensitization agents. Here, we report the sonosensitizing effects of Nano-Graphene Oxide (NGO) and compare them with gold nanoparticles (AuNPs), Iron Oxide nanoparticles (IONPs). Experiments were conducted to explore the effects of nanoparticle type and concentration, as well as ultrasound power, on transient heating up of the solutions exposed by 1 MHz ultrasound. Nanoparticles concentration was selected from 0.25 to 2.5 mg/ml and the solutions were exposed by ultrasound powers from 1 to 8 W. Real time temperature monitoring was done by a thermocouple and obtained data was analyzed. Temperature profiles of various nanoparticle solutions showed the higher heating rates, in comparison to water. Heating rise was strongly depended on nanoparticles concentration and ultrasound power. AuNPs showed a superior efficiency in heat generation enhancement in comparison to IONPs and NGO. Our result supports the idea of sonosensitizing capabilities of AuNPs, IONPs, and NGO. Targeted hyperthermia may be achievable by preferential loading of tumor with nanoparticles and subsequent ultrasound irradiation.

Targeting Endothelial Cells with Multifunctional GaN/Fe Nanoparticles

NASA Astrophysics Data System (ADS)

Braniste, Tudor; Tiginyanu, Ion; Horvath, Tibor; Raevschi, Simion; Andrée, Birgit; Cebotari, Serghei; Boyle, Erin C.; Haverich, Axel; Hilfiker, Andres

2017-08-01

In this paper, we report on the interaction of multifunctional nanoparticles with living endothelial cells. The nanoparticles were synthesized using direct growth of gallium nitride on zinc oxide nanoparticles alloyed with iron oxide followed by core decomposition in hydrogen flow at high temperature. Using transmission electron microscopy, we demonstrate that porcine aortic endothelial cells take up GaN-based nanoparticles suspended in the growth medium. The nanoparticles are deposited in vesicles and the endothelial cells show no sign of cellular damage. Intracellular inert nanoparticles are used as guiding elements for controlled transportation or designed spatial distribution of cells in external magnetic fields.

Optical properties of BaTiO3 nanoparticles and silver nanoprisms in polymer host matrices

NASA Astrophysics Data System (ADS)

Requena, Sebastian

Nanocomposites are materials comprised of a host matrix, such as glass or polymer, with embedded nanoparticles. Embedding nanoparticles into the host makes it possible to create materials with properties that are distinctly unique from those of their host and nanoparticle constituents. Nanocomposites can have superior mechanical, thermal, and optical properties compared to their host materials. We characterized the photoluminescent properties of BaTiO3 polymer nanocomposites and the effects of chemically modifying the nanoparticles surface on said properties. BaTiO3 nanopowders of average grain sizes 50 nm and 100 nm were functionalized by (3-aminopropyl)triethoxysilane (3APTS) and mixed with poly(methyl methacrylate)/toluene solution. The nanocomposites films morphology and chemical structure were studied via AFM and FTIR. The photoluminescence spectrum of the pure nanoparticles was composed of an emission at ˜3.0 eV and multiple bands centered at ˜2.5 eV. Surface functionalization of the BaTiO3 nanoparticles via 3APTS increased overall luminescence at room temperature while only enhancing the ˜3.0 eV emission at low-temperature. On the other hand, polymer coating of the functionalized nanoparticles significantly enhances ˜3.0 eV emissions while decreasing emissions associated with near-surface lattice distortions at ˜2.5 eV. Chemical modification of the surface with 3APTS and PMMA presents a pathway to tune and control the photoluminescent properties of BTO nanoparticles. We also present optical studies of two different size distributions of silver triangular nanoprisms, one with a dipole resonance at ˜520 nm and the other with a dipole resonance at ˜650 nm, placed in different media. The silver nanoprisms were embedded in a polyvinyl alcohol (PVA) polymer matrix and oriented by stretching the polymer/nanoprism nanocomposite films. We observe significantly increased linear dichroism in the region associated with the plasmonic in-plane dipole mode upon stretching. Additionally, there is a weaker linear dichroism in the region associated with out-of-plane modes, which vanish in the extinction spectrum of the stretched nanocomposite film. Our results show that these silver nanoprisms are promising as key components in wavelength-specific depolarizers and depolarization-based assays.

Ag, Co/graphene interactions and its effect on electrocatalytic oxygen reduction in alkaline media

NASA Astrophysics Data System (ADS)

Qaseem, Adnan; Chen, Fuyi; Wu, Xiaoqiang; Zhang, Nan; Xia, Zhenhai

2017-12-01

Silver nanoparticles supported on cobalt and nitrogen embedded reduced graphene oxide, Ag/Co-NGr, are synthesized by one-step hydrothermal route with remarkable catalytic activity for oxygen reduction reaction (ORR). As-synthesized electrocatalyst exhibits half-wave potential (0.82 V) comparable to commercial Pt/C (0.85 V), specific activity (0.45 mA cm-2) better than commercial Pt/C (0.35 mA cm-2) along with superior stability in alkaline environment (≈95% activity retention after 5000s compared to 80% for Pt/C). Moreover, Ag/Co-NGr is highly tolerant to methanol poisoning during ORR and delivers an excellent specific capacity of 789 mAh.g-1Zn with energy density of 947 Wh. kg-1 at a current density of 20 mA cm-2 in a Zn-air battery. For the first time, it is proven that particle size refinement and electronic perturbation of Ag nanoparticles take place due to metal-support interactions between Ag and Co/NGr. d-band center of Ag in Ag/Co-NGr upshifts toward the Fermi level with respect to the Ag/NGr as a result of charge transfer between Ag and Co/NGr. The superior catalytic activity and excellent stability of Ag/Co-NGr is attributed to the structural and electronic modification of Ag nanoparticles by Co and N elements on graphene.

Microbially-mediated method for synthesis of non-oxide semiconductor nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Phelps, Tommy J.; Lauf, Robert J.; Moon, Ji-Won

The invention is directed to a method for producing non-oxide semiconductor nanoparticles, the method comprising: (a) subjecting a combination of reaction components to conditions conducive to microbially-mediated formation of non-oxide semiconductor nanoparticles, wherein said combination of reaction components comprises i) anaerobic microbes, ii) a culture medium suitable for sustaining said anaerobic microbes, iii) a metal component comprising at least one type of metal ion, iv) a non-metal component comprising at least one non-metal selected from the group consisting of S, Se, Te, and As, and v) one or more electron donors that provide donatable electrons to said anaerobic microbes duringmore » consumption of the electron donor by said anaerobic microbes; and (b) isolating said non-oxide semiconductor nanoparticles, which contain at least one of said metal ions and at least one of said non-metals. The invention is also directed to non-oxide semiconductor nanoparticle compositions produced as above and having distinctive properties.« less

Thermal Decomposition Synthesis of Iron Oxide Nanoparticles with Diminished Magnetic Dead Layer by Controlled Addition of Oxygen.

PubMed

Unni, Mythreyi; Uhl, Amanda M; Savliwala, Shehaab; Savitzky, Benjamin H; Dhavalikar, Rohan; Garraud, Nicolas; Arnold, David P; Kourkoutis, Lena F; Andrew, Jennifer S; Rinaldi, Carlos

2017-02-28

Decades of research focused on size and shape control of iron oxide nanoparticles have led to methods of synthesis that afford excellent control over physical size and shape but comparatively poor control over magnetic properties. Popular synthesis methods based on thermal decomposition of organometallic precursors in the absence of oxygen have yielded particles with mixed iron oxide phases, crystal defects, and poorer than expected magnetic properties, including the existence of a thick "magnetically dead layer" experimentally evidenced by a magnetic diameter significantly smaller than the physical diameter. Here, we show how single-crystalline iron oxide nanoparticles with few defects and similar physical and magetic diameter distributions can be obtained by introducing molecular oxygen as one of the reactive species in the thermal decomposition synthesis. This is achieved without the need for any postsynthesis oxidation or thermal annealing. These results address a significant challenge in the synthesis of nanoparticles with predictable magnetic properties and could lead to advances in applications of magnetic nanoparticles.

Size distribution of magnetic iron oxide nanoparticles using Warren-Averbach XRD analysis

NASA Astrophysics Data System (ADS)

Mahadevan, S.; Behera, S. P.; Gnanaprakash, G.; Jayakumar, T.; Philip, J.; Rao, B. P. C.

2012-07-01

We use the Fourier transform based Warren-Averbach (WA) analysis to separate the contributions of X-ray diffraction (XRD) profile broadening due to crystallite size and microstrain for magnetic iron oxide nanoparticles. The profile shape of the column length distribution, obtained from WA analysis, is used to analyze the shape of the magnetic iron oxide nanoparticles. From the column length distribution, the crystallite size and its distribution are estimated for these nanoparticles which are compared with size distribution obtained from dynamic light scattering measurements. The crystallite size and size distribution of crystallites obtained from WA analysis are explained based on the experimental parameters employed in preparation of these magnetic iron oxide nanoparticles. The variation of volume weighted diameter (Dv, from WA analysis) with saturation magnetization (Ms) fits well to a core shell model wherein it is known that Ms=Mbulk(1-6g/Dv) with Mbulk as bulk magnetization of iron oxide and g as magnetic shell disorder thickness.

Investigating the oxidation mechanism of tantalum nanoparticles at high heating rates

NASA Astrophysics Data System (ADS)

DeLisio, Jeffery B.; Wang, Xizheng; Wu, Tao; Egan, Garth C.; Jacob, Rohit J.; Zachariah, Michael R.

2017-12-01

Reduced diffusion length scales and increased specific surface areas of nanosized metal fuels have recently demonstrated increased reaction rates for these systems, increasing their relevance in a wide variety of applications. The most commonly employed metal fuel, aluminum, tends to oxidize rapidly near its melting point (660 °C) in addition to undergoing a phase change of the nascent oxide shell. To further expand on the understanding of nanosized metal fuel oxidation, tantalum nanoparticles were studied due to their high melting point (3017 °C) in comparison to aluminum. Both traditional slow heating rate and in-situ high heating rate techniques were used to probe the oxidation of tantalum nanoparticles in oxygen containing environments in addition to nanothermite mixtures. When oxidized by gas phase oxygen, the oxide shell of the tantalum nanoparticles rapidly crystallized creating cracks that may attribute to enhanced oxygen diffusion into the particle. In the case of tantalum based nanothermites, oxide shell crystallization was shown to induce reactive sintering with the metal oxide resulting in a narrow range of ignition temperatures independent of the metal oxide used. The oxidation mechanism was modeled using the Deal-Grove model to extract rate parameters, and theoretical burn times for tantalum based nanocomposites were calculated.

UNS S31603 Stainless Steel Tungsten Inert Gas Welds Made with Microparticle and Nanoparticle Oxides

PubMed Central

Tseng, Kuang-Hung; Lin, Po-Yu

2014-01-01

The purpose of this study was to investigate the difference between tungsten inert gas (TIG) welding of austenitic stainless steel assisted by microparticle oxides and that assisted by nanoparticle oxides. SiO2 and Al2O3 were used to investigate the effects of the thermal stability and the particle size of the activated compounds on the surface appearance, geometric shape, angular distortion, delta ferrite content and Vickers hardness of the UNS S31603 stainless steel TIG weld. The results show that the use of SiO2 leads to a satisfactory surface appearance compared to that of the TIG weld made with Al2O3. The surface appearance of the TIG weld made with nanoparticle oxide has less flux slag compared with the one made with microparticle oxide of the same type. Compared with microparticle SiO2, the TIG welding with nanoparticle SiO2 has the potential benefits of high joint penetration and less angular distortion in the resulting weldment. The TIG welding with nanoparticle Al2O3 does not result in a significant increase in the penetration or reduction of distortion. The TIG welding with microparticle or nanoparticle SiO2 uses a heat source with higher power density, resulting in a higher ferrite content and hardness of the stainless steel weld metal. In contrast, microparticle or nanoparticle Al2O3 results in no significant difference in metallurgical properties compared to that of the C-TIG weld metal. Compared with oxide particle size, the thermal stability of the oxide plays a significant role in enhancing the joint penetration capability of the weld, for the UNS S31603 stainless steel TIG welds made with activated oxides. PMID:28788704

Graphene Oxide-Promoted Reshaping and Coarsening of Gold Nanorods and Nanoparticles

PubMed Central

Pan, Hanqing; Low, Serena; Weerasuriya, Nisala; Shon, Young-Seok

2015-01-01

This paper describes thermally induced reshaping and coarsening behaviors of gold nanorods and nanoparticles immobilized on the surface of graphene oxide. Cetyltrimethylammonium bromide-stabilized gold nanorods with an aspect ratio of ~3.5 (54:15 nm) and glutathione-capped gold nanoparticles with an average core size of ~3 nm were synthesized and self-assembled onto the surface of graphene oxide. The hybrid materials were then heated at different temperatures ranging from 50 to 300 °C. The effects of heat treatments were monitored using UV–vis spectroscopy and transmission electron microscopy (TEM). These results were directly compared with those of heat-treated free-standing gold nanorods and nanoparticles without graphene oxide to understand the heat-induced morphological changes of the nanohybrids. The obtained results showed that the gold nanorods would undergo a complete reshaping to spherical particles at the temperature of 50 °C when they are assembled on graphene oxide. In comparison, the complete reshaping of free-standing gold nanorods to spherical particles would ultimately require a heating of the samples at 200 °C. In addition, the spherical gold nanoparticles immobilized on graphene oxide would undergo a rapid coarsening at the temperature of 100–150 °C, which was lower than the temperature (150–200 °C) required for visible coarsening of free-standing gold nanoparticles. The results indicated that graphene oxide facilitates the reshaping and coarsening of gold nanorods and nanoparticles, respectively, during the heat treatments. The stripping and spillover of stabilizing ligands promoted by graphene oxide are proposed to be the main mechanism for the enhancements in the heat-induced transformations of nanohybrids. PMID:25611371

UNS S31603 Stainless Steel Tungsten Inert Gas Welds Made with Microparticle and Nanoparticle Oxides.

PubMed

Tseng, Kuang-Hung; Lin, Po-Yu

2014-06-20

The purpose of this study was to investigate the difference between tungsten inert gas (TIG) welding of austenitic stainless steel assisted by microparticle oxides and that assisted by nanoparticle oxides. SiO₂ and Al₂O₃ were used to investigate the effects of the thermal stability and the particle size of the activated compounds on the surface appearance, geometric shape, angular distortion, delta ferrite content and Vickers hardness of the UNS S31603 stainless steel TIG weld. The results show that the use of SiO₂ leads to a satisfactory surface appearance compared to that of the TIG weld made with Al₂O₃. The surface appearance of the TIG weld made with nanoparticle oxide has less flux slag compared with the one made with microparticle oxide of the same type. Compared with microparticle SiO₂, the TIG welding with nanoparticle SiO₂ has the potential benefits of high joint penetration and less angular distortion in the resulting weldment. The TIG welding with nanoparticle Al₂O₃ does not result in a significant increase in the penetration or reduction of distortion. The TIG welding with microparticle or nanoparticle SiO₂ uses a heat source with higher power density, resulting in a higher ferrite content and hardness of the stainless steel weld metal. In contrast, microparticle or nanoparticle Al₂O₃ results in no significant difference in metallurgical properties compared to that of the C-TIG weld metal. Compared with oxide particle size, the thermal stability of the oxide plays a significant role in enhancing the joint penetration capability of the weld, for the UNS S31603 stainless steel TIG welds made with activated oxides.

Antibacterial Activity of Polymer Coated Cerium Oxide Nanoparticles

PubMed Central

Shah, Vishal; Shah, Shreya; Shah, Hirsh; Rispoli, Fred J.; McDonnell, Kevin T.; Workeneh, Selam; Karakoti, Ajay; Kumar, Amit; Seal, Sudipta

2012-01-01

Cerium oxide nanoparticles have found numerous applications in the biomedical industry due to their strong antioxidant properties. In the current study, we report the influence of nine different physical and chemical parameters: pH, aeration and, concentrations of MgSO4, CaCl2, KCl, natural organic matter, fructose, nanoparticles and Escherichia coli, on the antibacterial activity of dextran coated cerium oxide nanoparticles. A least-squares quadratic regression model was developed to understand the collective influence of the tested parameters on the anti-bacterial activity and subsequently a computer-based, interactive visualization tool was developed. The visualization allows us to elucidate the effect of each of the parameters in combination with other parameters, on the antibacterial activity of nanoparticles. The results indicate that the toxicity of CeO2 NPs depend on the physical and chemical environment; and in a majority of the possible combinations of the nine parameters, non-lethal to the bacteria. In fact, the cerium oxide nanoparticles can decrease the anti-bacterial activity exerted by magnesium and potassium salts. PMID:23110109

Plasmon-induced optical switching of electrical conductivity in porous anodic aluminum oxide films encapsulated with silver nanoparticle arrays.

PubMed

Huang, Chen-Han; Lin, Hsing-Ying; Lau, Ben-Chao; Liu, Chih-Yi; Chui, Hsiang-Chen; Tzeng, Yonhua

2010-12-20

We report on plasmon induced optical switching of electrical conductivity in two-dimensional (2D) arrays of silver (Ag) nanoparticles encapsulated inside nanochannels of porous anodic aluminum oxide (AAO) films. The reversible switching of photoconductivity greatly enhanced by an array of closely spaced Ag nanoparticles which are isolated from each other and from the ambient by thin aluminum oxide barrier layers are attributed to the improved electron transport due to the localized surface plasmon resonance and coupling among Ag nanoparticles. The photoconductivity is proportional to the power, and strongly dependent on the wavelength of light illumination. With Ag nanoparticles being isolated from the ambient environments by a thin layer of aluminum oxide barrier layer of controlled thickness in nanometers to tens of nanometers, deterioration of silver nanoparticles caused by environments is minimized. The electrochemically fabricated nanostructured Ag/AAO is inexpensive and promising for applications to integrated plasmonic circuits and sensors.

Mobility and Oxidation of Adsorbed CO on Shape-Controlled Pt Nanoparticles in Acidic Medium.

PubMed

Farias, Manuel J S; Busó-Rogero, Carlos; Vidal-Iglesias, Francisco J; Solla-Gullón, José; Camara, Giuseppe A; Feliu, Juan M

2017-01-31

The knowledge about how CO occupies and detaches from specific surface sites on well-structured Pt surfaces provides outstanding information on both dynamics/mobility of CO ads and oxidation of this molecule under electrochemical conditions. This work reports how the potentiostatic growth of different coverage CO adlayers evolves with time on both cubic and octahedral Pt nanoparticles in acidic medium. Data suggest that during the growth of the CO adlayer, CO ads molecules slightly shift toward low coordination sites only on octahedral Pt nanoparticles, so that these undercoordinated sites are the first filled on octahedral Pt nanoparticles. Conversely, on cubic Pt nanoparticles, adsorbed CO behaves as an immobile species, and low coordinated sites as well as (100) terraces are apparently filled uniformly and simultaneously. However, once the adlayer is complete, irrespectively of whether the CO is oxidized in a single step or in a sequence of different potential steps, results suggest that CO ads behaves as an immobile species during its oxidation on both octahedral and cubic Pt nanoparticles.

Preliminary study of injury from heating systemically delivered, nontargeted dextran–superparamagnetic iron oxide nanoparticles in mice

PubMed Central

Kut, Carmen; Zhang, Yonggang; Hedayati, Mohammad; Zhou, Haoming; Cornejo, Christine; Bordelon, David; Mihalic, Jana; Wabler, Michele; Burghardt, Elizabeth; Gruettner, Cordula; Geyh, Alison; Brayton, Cory; Deweese, Theodore L; Ivkov, Robert

2013-01-01

Aim To assess the potential for injury to normal tissues in mice due to heating systemically delivered magnetic nanoparticles in an alternating magnetic field (AMF). Materials & methods Twenty three male nude mice received intravenous injections of dextran–superparamagnetic iron oxide nanoparticles on days 1–3. On day 6, they were exposed to AMF. On day 7, blood, liver and spleen were harvested and analyzed. Results Iron deposits were detected in the liver and spleen. Mice that had received a high-particle dose and a high AMF experienced increased mortality, elevated liver enzymes and significant liver and spleen necrosis. Mice treated with low-dose superparamagnetic iron oxide nanoparticles and a low AMF survived, but had elevated enzyme levels and local necrosis in the spleen. Conclusion Magnetic nanoparticles producing only modest heat output can cause damage, and even death, when sequestered in sufficient concentrations. Dextran–superparamagnetic iron oxide nanoparticles are deposited in the liver and spleen, making these the sites of potential toxicity. PMID:22830502

Nano-antioxidants: An emerging strategy for intervention against neurodegenerative conditions.

PubMed

Sandhir, Rajat; Yadav, Aarti; Sunkaria, Aditya; Singhal, Nitin

2015-10-01

Oxidative stress has for long been linked to the neuronal cell death in many neurodegenerative conditions. Conventional antioxidant therapies have been less effective in preventing neuronal damage caused by oxidative stress due to their inability to cross the blood brain barrier. Nanoparticle antioxidants constitute a new wave of antioxidant therapies for prevention and treatment of diseases involving oxidative stress. It is believed that nanoparticle antioxidants have strong and persistent interactions with biomolecules and would be more effective against free radical induced damage. Nanoantioxidants include inorganic nanoparticles possessing intrinsic antioxidant properties, nanoparticles functionalized with antioxidants or antioxidant enzymes to function as an antioxidant delivery system. Nanoparticles containing antioxidants have shown promise as high-performance therapeutic nanomedicine in attenuating oxidative stress with potential applications in treating and preventing neurodegenerative conditions. However, to realize the full potential of nanoantioxidants, negative aspects associated with the use of nanoparticles need to be overcome to validate their long term applications. Copyright © 2015 Elsevier Ltd. All rights reserved.

Magnetic Nanoparticle-Based Imaging of RNA Transcripts in Breast Cancer Cells

DTIC Science & Technology

2008-06-30

control (Months 33 – 36). These studies have not yet commenced. KEY RESEARCH ACCOMPLISHMENTS: - Synthesized dextran-coated iron oxide NPs with...Size, charge, and concentration dependent uptake of iron oxide nanoparticles by non-phagocytic cells: a comparative study of USPIO, SSPIO, and MPIO...A. (2008) Size, charge, and concentration dependent uptake of iron oxide nanoparticles by non-phagocytic cells: a comparative study of USPIO, SSPIO

Solid-stabilized emulsion formation using stearoyl lactylate coated iron oxide nanoparticles

NASA Astrophysics Data System (ADS)

Vengsarkar, Pranav S.; Roberts, Christopher B.

2014-10-01

Iron oxide nanoparticles can exhibit highly tunable physicochemical properties that are extremely important in applications such as catalysis, biomedicine and environmental remediation. The small size of iron oxide nanoparticles can be used to stabilize oil-in-water Pickering emulsions due to their high energy of adsorption at the interface of oil droplets in water. The objective of this work is to investigate the effect of the primary particle characteristics and stabilizing agent chemistry on the stability of oil-in-water Pickering emulsions. Iron oxide nanoparticles were synthesized by the co-precipitation method using stoichiometric amounts of Fe2+ and Fe3+ salts. Sodium stearoyl lactylate (SSL), a Food and Drug Administration approved food additive, was used to functionalize the iron oxide nanoparticles. SSL is useful in the generation of fat-in-water emulsions due to its high hydrophilic-lipophilic balance and its bilayer-forming capacity. Generation of a monolayer or a bilayer coating on the nanoparticles was controlled through systematic changes in reagent concentrations. The coated particles were then characterized using various analytical techniques to determine their size, their crystal structure and surface functionalization. The capacity of these bilayer coated nanoparticles to stabilize oil-in-water emulsions under various salt concentrations and pH values was also systematically determined using various characterization techniques. This study successfully demonstrated the ability to synthesize iron oxide nanoparticles (20-40 nm) coated with SSL in order to generate stable Pickering emulsions that were pH-responsive and resistant to significant destabilization in a saline environment, thereby lending themselves to applications in advanced oil spill recovery and remediation.

Magnetic resonance cell-tracking studies: spectrophotometry-based method for the quantification of cellular iron content after loading with superparamagnetic iron oxide nanoparticles.

PubMed

Böhm, Ingrid

2011-08-01

The purpose of this article is to present a user-friendly tool for quantifying the iron content of superparamagnetic labeled cells before cell tracking by magnetic resonance imaging (MRI). Iron quantification was evaluated by using Prussian blue staining and spectrophotometry. White blood cells were labeled with superparamagnetic iron oxide (SPIO) nanoparticles. Labeling was confirmed by light microscopy. Subsequently, the cells were embedded in a phantom and scanned on a 3 T magnetic resonance tomography (MRT) whole-body system. Mean peak wavelengths λ(peak) was determined at A(720 nm) (range 719-722 nm). Linearity was proven for the measuring range 0.5 to 10 μg Fe/mL (r  =  .9958; p  =  2.2 × 10(-12)). The limit of detection was 0.01 μg Fe/mL (0.1785 mM), and the limit of quantification was 0.04 μg Fe/mL (0.714 mM). Accuracy was demonstrated by comparison with atomic absorption spectrometry. Precision and robustness were also proven. On T(2)-weighted images, signal intensity varied according to the iron concentration of SPIO-labeled cells. Absorption spectrophotometry is both a highly sensitive and user-friendly technique that is feasible for quantifying the iron content of magnetically labeled cells. The presented data suggest that spectrophotometry is a promising tool for promoting the implementation of magnetic resonance-based cell tracking in routine clinical applications (from bench to bedside).

Nanoparticles containing allotropes of carbon have genotoxic effects on glioblastoma multiforme cells

PubMed Central

Hinzmann, Mateusz; Jaworski, Sławomir; Kutwin, Marta; Jagiełło, Joanna; Koziński, Rafał; Wierzbicki, Mateusz; Grodzik, Marta; Lipińska, Ludwika; Sawosz, Ewa; Chwalibog, Andrè

2014-01-01

The carbon-based nanomaterial family consists of nanoparticles containing allotropes of carbon, which may have a number of interactions with biological systems. The objective of this study was to evaluate the toxicity of nanoparticles comprised of pristine graphene, reduced graphene oxide, graphene oxide, graphite, and ultradispersed detonation diamond in a U87 cell line. The scope of the work consisted of structural analysis of the nanoparticles using transmission electron microscopy, evaluation of cell morphology, and assessment of cell viability by Trypan blue assay and level of DNA fragmentation of U87 cells after 24 hours of incubation with 50 μg/mL carbon nanoparticles. DNA fragmentation was studied using single-cell gel electrophoresis. Incubation with nanoparticles containing the allotropes of carbon did not alter the morphology of the U87 cancer cells. However, incubation with pristine graphene and reduced graphene oxide led to a significant decrease in cell viability, whereas incubation with graphene oxide, graphite, and ultradispersed detonation diamond led to a smaller decrease in cell viability. The results of a comet assay demonstrated that pristine graphene, reduced graphene oxide, graphite, and ultradispersed detonation diamond caused DNA damage and were therefore genotoxic in U87 cells, whereas graphene oxide was not. PMID:24876774

Oxidation behaviour of Fe-Ni alloy nanoparticles synthesized by thermal plasma route

NASA Astrophysics Data System (ADS)

Ghodke, Neha; Kamble, Shalaka; Raut, Suyog; Puranik, Shridhar; Bhoraskar, S. V.; Rayaprol, Sudhindra; Mathe, V. L.

2018-04-01

Here we report synthesis of Fe-Ni nanoparticles using thermal plasma route. In thermal plasma, gas phase nucleation and growth at sufficiently higher temperature is observed. The synthesized Fe-Ni nanoparticles are examined by X-ray Diffraction, Raman Spectroscopy, Vibrating Sample Magnetometer and Thermo gravimetric Analysis. Formation of 16-21 nm sized Fe-Ni nanoparticles having surface oxidation show maximum value of magnetization of ˜107 emu/g. The sample synthesized at relatively low power (4kW) show presence of carbonaceous species whereas the high power (6 kW) synthesis does not depicts carbonaceous species. The presence of carbonaceous species protects oxidation of the nanoparticles significantly as evidenced from TGA data.

Increased optical contrast in imaging of epidermal growth factor receptor using magnetically actuated hybrid gold/iron oxide nanoparticles

NASA Astrophysics Data System (ADS)

Aaron, Jesse S.; Oh, Junghwan; Larson, Timothy A.; Kumar, Sonia; Milner, Thomas E.; Sokolov, Konstantin V.

2006-12-01

We describe a new approach for optical imaging that combines the advantages of molecularly targeted plasmonic nanoparticles and magnetic actuation. This combination is achieved through hybrid nanoparticles with an iron oxide core surrounded by a gold layer. The nanoparticles are targeted in-vitro to epidermal growth factor receptor, a common cancer biomarker. The gold portion resonantly scatters visible light giving a strong optical signal and the superparamagnetic core provides a means to externally modulate the optical signal. The combination of bright plasmon resonance scattering and magnetic actuation produces a dramatic increase in contrast in optical imaging of cells labeled with hybrid gold/iron oxide nanoparticles.

Ex vivo assessment of polyol coated-iron oxide nanoparticles for MRI diagnosis applications: toxicological and MRI contrast enhancement effects

NASA Astrophysics Data System (ADS)

Bomati-Miguel, Oscar; Miguel-Sancho, Nuria; Abasolo, Ibane; Candiota, Ana Paula; Roca, Alejandro G.; Acosta, Milena; Schwartz, Simó; Arus, Carles; Marquina, Clara; Martinez, Gema; Santamaria, Jesus

2014-03-01

Polyol synthesis is a promising method to obtain directly pharmaceutical grade colloidal dispersion of superparamagnetic iron oxide nanoparticles (SPIONs). Here, we study the biocompatibility and performance as T2-MRI contrast agents (CAs) of high quality magnetic colloidal dispersions (average hydrodynamic aggregate diameter of 16-27 nm) consisting of polyol-synthesized SPIONs (5 nm in mean particle size) coated with triethylene glycol (TEG) chains (TEG-SPIONs), which were subsequently functionalized to carboxyl-terminated meso-2-3-dimercaptosuccinic acid (DMSA) coated-iron oxide nanoparticles (DMSA-SPIONs). Standard MTT assays on HeLa, U87MG, and HepG2 cells revealed that colloidal dispersions of TEG-coated iron oxide nanoparticles did not induce any loss of cell viability after 3 days incubation with dose concentrations below 50 μg Fe/ml. However, after these nanoparticles were functionalized with DMSA molecules, an increase on their cytotoxicity was observed, so that particles bearing free terminal carboxyl groups on their surface were not cytotoxic only at low concentrations (<10 μg Fe/ml). Moreover, cell uptake assays on HeLa and U87MG and hemolysis tests have demonstrated that TEG-SPIONs and DMSA-SPIONs were well internalized by the cells and did not induce any adverse effect on the red blood cells at the tested concentrations. Finally, in vitro relaxivity measurements and post mortem MRI studies in mice indicated that both types of coated-iron oxide nanoparticles produced higher negative T2-MRI contrast enhancement than that measured for a similar commercial T2-MRI CAs consisting in dextran-coated ultra-small iron oxide nanoparticles (Ferumoxtran-10). In conclusion, the above attributes make both types of as synthesized coated-iron oxide nanoparticles, but especially DMSA-SPIONs, promising candidates as T2-MRI CAs for nanoparticle-enhanced MRI diagnosis applications.

Fabrication of transparent ceramics using nanoparticles

DOEpatents

Cherepy, Nerine J; Tillotson, Thomas M; Kuntz, Joshua D; Payne, Stephen A

2012-09-18

A method of fabrication of a transparent ceramic using nanoparticles synthesized via organic acid complexation-combustion includes providing metal salts, dissolving said metal salts to produce an aqueous salt solution, adding an organic chelating agent to produce a complexed-metal sol, heating said complexed-metal sol to produce a gel, drying said gel to produce a powder, combusting said powder to produce nano-particles, calcining said nano-particles to produce oxide nano-particles, forming said oxide nano-particles into a green body, and sintering said green body to produce the transparent ceramic.

Metallic-nanoparticles-enhanced fluorescence from individual micron-sized aerosol particles on-the-fly.

PubMed

Sivaprakasam, Vasanthi; Hart, Matthew B; Jain, Vaibhav; Eversole, Jay D

2014-08-11

Fluorescence spectra from individual aerosol particles that were either coated or embedded with metallic nanoparticles (MNPs) was acquired on-the-fly using 266 nm and 355 nm excitation. Using aqueous suspensions of MNPs with either polystyrene latex (PSL) spheres or dissolved proteins (tryptophan or ovalbumin), we generated PSL spheres coated with MNPs, or protein clusters embedded with MNPs as aerosols. Both enhanced and quenched fluorescence intensities were observed as a function of MNP concentration. Optimizing MNP material, size and spacing should yield enhanced sensitivity for specific aerosol materials that could be exploited to improve detection limits of single-particle, on-the-fly fluorescence or Raman based spectroscopic sensors.

Magneto-optical waveguides made of cobalt ferrite nanoparticles embedded in silica/zirconia organic-inorganic matrix

NASA Astrophysics Data System (ADS)

Choueikani, Fadi; Royer, François; Jamon, Damien; Siblini, Ali; Rousseau, Jean Jacques; Neveu, Sophie; Charara, Jamal

2009-02-01

This paper describes a way to develop magneto-optical waveguides via sol-gel process. They are made of cobalt ferrite nanoparticles embedded in a silica/zirconia matrix. Thin films are coated on glass substrate using the dip-coating technique. Annealing and UV treatment are applied to finalize sample preparation. Therefore, planar waveguides combining magneto-optical properties with a low refractive index (≈1,5) are obtained. M-lines and free space ellipsometry measurements show a specific Faraday rotation of 250°/cm and a modal birefringence of 1×10-4 at 820 nm. Thus, the mode conversion efficiency can reach a maximum value around 56%.

Simultaneous Oxidation and Sequestration of As(III) from Water by Using Redox Polymer-Based Fe(III) Oxide Nanocomposite.

PubMed

Zhang, Xiaolin; Wu, Mengfei; Dong, Hao; Li, Hongchao; Pan, Bingcai

2017-06-06

Water decontamination from As(III) is an urgent but still challenging task. Herein, we fabricated a bifunctional nanocomposite HFO@PS-Cl for highly efficient removal of As(III), with active chlorine covalently binding spherical polystyrene host for in situ oxidation of As(III) to As(V), and Fe(III) hydroxide (HFO) nanoparticles (NPs) embedded inside for specific As(V) removal. HFO@PS-Cl could work effectively in a wide pH range (5-9), and other substances like sulfate, chloride, bicarbonate, silicate, and humic acid exert insignificant effect on As(III) removal. As(III) sequestration is realized via two pathways, that is, oxidation to As(V) by the active chlorine followed by specific As(V) adsorption onto HFO NPs, and As(III) adsorption onto HFO NPs followed by oxidation to As(V). The exhausted HFO@PS-Cl could be refreshed for cyclic runs with insignificant capacity loss by the combined regeneration strategy, that is, alkaline solution to rinse the adsorbed As(V) and NaClO solution to renew the host oxidation capability. In addition, fixed-bed experiments demonstrated that the HFO@PS-Cl column could generate >1760 bed volume (BV) effluent from a synthetic As(III)-containing groundwater to meet the drinking water standard (<10 μg As/L), whereas other two HFO nanocomposites, HFO@PS-N and HFO@D201 could only generate 450 and 600 BV effluents under otherwise identical conditions.

Viscous properties of aluminum oxide nanotubes and aluminium oxide nanoparticles - silicone oil suspensions

NASA Astrophysics Data System (ADS)

Thapa, Ram; French, Steven; Delgado, Adrian; Ramos, Carlos; Gutierrez, Jose; Chipara, Mircea; Lozano, Karen

2010-03-01

Electrorheological (ER) fluids consisting of γ-aluminum oxide nanotubes and γ-aluminum oxide nanoparticles dispersed within silicone oil were prepared. The relationship between shear stress and shear rate was measured and theoretically simulated by using an extended Bingham model for both the rheological and electrorheological features of these systems. Shear stress and viscosity showed a sharp increase for the aluminum oxide nanotubes suspensions subjected to applied electric fields whereas aluminum oxide nanoparticles suspensions showed a moderate change. It was found that the transition from liquid to solid state (mediated by the applied electric field) can be described by a power law and that for low applied voltages the relationship is almost linear.

The effect of carboxylic acids on the oxidation of coated iron oxide nanoparticles

NASA Astrophysics Data System (ADS)

Lengyel, Attila; Tolnai, Gyula; Klencsár, Zoltán; Garg, Vijayendra Kumar; de Oliveira, Aderbal Carlos; Herojit Singh, L.; Homonnay, Zoltán; Szalay, Roland; Németh, Péter; Szabolcs, Bálint; Ristic, Mira; Music, Svetozar; Kuzmann, Ernő

2018-05-01

57Fe Mössbauer spectroscopy, XRD, and TEM were used to investigate the effect of mandelic- and salicylic acid coatings on the iron oxide nanoparticles. These two carboxylic acids have similar molecules size and stoichiometry, but different structure and acidity. Significant differences were observed between the Mössbauer spectra of samples coated with mandelic acid and salicylic acid. These results indicate that the occurrence of iron microenvironments in the mandelic- and salicylic acid-coated iron oxide nanoparticles is different. The results can be interpreted in terms of the influence of the acidity of carboxylic acids on the formation, core/shell structure, and oxidation of coated iron oxide nanocomposites.

Investigation of the Ligand-Nanoparticle Interface: A Cryogenic Approach for Preserving Surface Chemistry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Karakoti, Ajay S.; Yang, Ping; Wang, Weina

2018-02-15

Ligand functionalized nanoparticles have replaced bare nanoparticles from most biological applications. These applications require tight control over size and stability of nanoparticles in aqueous medium. Understanding the mechanism of interaction of nanoparticle surfaces with functional groups of different organic ligands such as carboxylic acids is confounding despite the two decades of research on nanoparticles because of the inability to characterize their surfaces in their immediate environment. Often the surface interaction is understood by correlating the information available, in a piecemeal approach, from surface sensitive spectroscopic information of ligands and the bulk and surface information of nanoparticles. In present study wemore » report the direct interaction of 5-7 nm cerium oxide nanoparticles surface with acetic acid. In-situ XPS study was carried out by freezing the aqueous solution of nanoparticles to liquid nitrogen temperatures. Analysis of data collected concurrently from the ligands as well as functionalized frozen cerium oxide nanoparticles show that the acetic acid binds to the ceria surface in both dissociated and molecular state with equal population over the surface. The cerium oxide surface was populated predominantly with Ce4+ ions consistent with the thermal hydrolysis synthesis. DFT calculations reveal that the acetate ions bind more strongly to the cerium oxide nanoparticles as compared to the water and can replace the hydration sphere of nanoparticles resulting in high acetate/acetic surface coverage. These findings reveal molecular level interaction between the nanoparticle surfaces and ligands giving a better understanding of how materials behave in their immediate aqueous environment. This study also proposes a simple and elegant methodology to directly study the surface functional groups attached to nanoparticles in their immediate aqueous environment.« less

Investigation of the Ligand–Nanoparticle Interface: A Cryogenic Approach for Preserving Surface Chemistry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Karakoti, Ajay S.; Yang, Ping; Wang, Weina

Ligand functionalized nanoparticles have replaced bare nanoparticles from most biological applications. These applications require tight control over size and stability of nanoparticles in aqueous medium. Understanding the mechanism of interaction of nanoparticle surfaces with functional groups of different organic ligands such as carboxylic acids is confounding despite the two decades of research on nanoparticles because of the inability to characterize their surfaces in their immediate environment. Often the surface interaction is understood by correlating the information available, in a piecemeal approach, from surface sensitive spectroscopic information of ligands and the bulk and surface information of nanoparticles. In present study wemore » report the direct interaction of 5-7 nm cerium oxide nanoparticles surface with acetic acid. In-situ XPS study was carried out by freezing the aqueous solution of nanoparticles to liquid nitrogen temperatures. Analysis of data collected concurrently from the ligands as well as functionalized frozen cerium oxide nanoparticles show that the acetic acid binds to the ceria surface in both dissociated and molecular state with equal population over the surface. The cerium oxide surface was populated predominantly with Ce4+ ions consistent with the thermal hydrolysis synthesis. DFT calculations reveal that the acetate ions bind more strongly to the cerium oxide nanoparticles as compared to the water and can replace the hydration sphere of nanoparticles resulting in high acetate/acetic surface coverage. These findings reveal molecular level interaction between the nanoparticle surfaces and ligands giving a better understanding of how materials behave in their immediate aqueous environment. This study also proposes a simple and elegant methodology to directly study the surface functional groups attached to nanoparticles in their immediate aqueous environment.« less

Electron spin resonance spectroscopy for immunoassay using iron oxide nanoparticles as probe.

PubMed

Jiang, Jia; Tian, Sizhu; Wang, Kun; Wang, Yang; Zang, Shuang; Yu, Aimin; Zhang, Ziwei

2018-02-01

With the help of iron oxide nanoparticles, electron spin resonance spectroscopy (ESR) was applied to immunoassay. Iron oxide nanoparticles were used as the ESR probe in order to achieve an amplification of the signal resulting from the large amount of Fe 3+ ion enclosed in each nanoparticle. Rabbit IgG was used as antigen to test this method. Polyclonal antibody of rabbit IgG was used as antibody to detect the antigen. Iron oxide nanoparticle with a diameter of either 10 or 30 nm was labeled to the antibody, and Fe 3+ in the nanoparticle was probed for ESR signal. The sepharose beads were used as solid phase to which rabbit IgG was conjugated. The nanoparticle-labeled antibody was first added in the sample containing antigen, and the antigen-conjugated sepharose beads were then added into the sample. The nanoparticle-labeled antibody bound to the antigen on sepharose beads was separated from the sample by centrifugation and measured. We found that the detection ranges of the antigen obtained with nanoparticles of different sizes were different because the amount of antibody on nanoparticles of 10 nm was about one order of magnitude higher than that on nanoparticles of 30 nm. When 10 nm nanoparticle was used as probe, the upper limit of detection was 40.00 μg mL -1 , and the analytical sensitivity was 1.81 μg mL -1 . When 30 nm nanoparticle was used, the upper limit of detection was 3.00 μg mL -1 , and the sensitivity was 0.014 and 0.13 μg mL -1 depending on the ratio of nanoparticle to antibody. Graphical abstract Schematic diagram of procedure and ESR spectra.

Gold Nanoparticles as a Photothermal Agent in Cancer Therapy: The Thermal Ablation Characteristic Length.

PubMed

Grosges, Thomas; Barchiesi, Dominique

2018-05-31

In cancer therapy, the thermal ablation of diseased cells by embedded nanoparticles is one of the known therapies. It is based on the absorption of the energy of the illuminating laser by nanoparticles. The resulting heating of nanoparticles kills the cell where these photothermal agents are embedded. One of the main constraints of this therapy is preserving the surrounding healthy cells. Therefore, two parameters are of interest. The first one is the thermal ablation characteristic length, which corresponds to an action distance around the nanoparticles for which the temperature exceeds the ablation threshold. This critical geometric parameter is related to the expected conservation of the body temperature in the surroundings of the diseased cell. The second parameter is the temperature that should be reached to achieve active thermal agents. The temperature depends on the power of the illuminating laser, on the size of nanoparticles and on their physical properties. The purpose of this paper is to propose behavior laws under the constraints of both the body temperature at the boundary of the cell to preserve surrounding cells and an acceptable range of temperature in the target cell. The behavior laws are deduced from the finite element method, which is able to model aggregates of nanoparticles. We deduce sensitivities to the laser power and to the particle size. We show that the tuning of the temperature elevation and of the distance of action of a single nanoparticle is not significantly affected by variations of the particle size and of the laser power. Aggregates of nanoparticles are much more efficient, but represent a potential risk to the surrounding cells. Fortunately, by tuning the laser power, the thermal ablation characteristic length can be controlled.

Peptide conjugated magnetic nanoparticles for magnetically mediated energy delivery to lung cancer cells

PubMed Central

Hauser, Anastasia K; Anderson, Kimberly W; Hilt, J Zach

2016-01-01

Aim: In the present study, we examine the effects of internalized peptide-conjugated iron oxide nanoparticles and their ability to locally convert alternating magnetic field (AMF) energy into other forms of energy (e.g., heat and rotational work). Materials & methods: Dextran-coated iron oxide nanoparticles were functionalized with a cell penetrating peptide and after internalization by A549 and H358 cells were activated by an AMF. Results: TAT-functionalized nanoparticles and AMF exposure increased reactive oxygen species generation compared with the nanoparticle system alone. The TAT-functionalized nanoparticles induced lysosomal membrane permeability and mitochondrial membrane depolarization, but these effects were not further enhanced by AMF treatment. Although not statistically significant, there are trends suggesting an increase in apoptosis via the Caspase 3/7 pathways when cells are exposed to TAT-functionalized nanoparticles combined with AMF. Conclusion: Our results indicate that internalized TAT-functionalized iron oxide nanoparticles activated by an AMF elicit cellular responses without a measurable temperature rise. PMID:27388639

The development of latent fingerprints by zinc oxide and tin oxide nanoparticles prepared by precipitation technique

NASA Astrophysics Data System (ADS)

Luthra, Deepali; Kumar, Sacheen

2018-05-01

Fingerprints are the very important evidence at the crime scene which must be developed clearly with shortest duration of time to solve the case. Metal oxide nanoparticles could be the mean to develop the latent fingerprints. Zinc oxide and Tin Oxide Nanoparticles were prepared by using chemical precipitation technique which were dried and characterized by X-ray diffraction, UV-Visible spectroscopy and FTIR. The size of zinc oxide crystallite was found to be 14.75 nm with minimum reflectance at 360 nm whereas tin oxide have the size of 90 nm and reflectance at minimum level 321 nm. By using these powdered samples on glass, plastic and glossy cardboard, latent fingerprints were developed. Zinc oxide was found to be better candidate than tin oxide for the fingerprint development on all the three types of substrates.

Control of Gallium Oxide Growth on Liquid Metal Eutectic Gallium/Indium Nanoparticles via Thiolation.

PubMed

Farrell, Zachary J; Tabor, Christopher

2018-01-09

Eutectic gallium-indium alloy (EGaIn, a room-temperature liquid metal) nanoparticles are of interest for their unique potential uses in self-healing and flexible electronic devices. One reason for their interest is due to a passivating oxide skin that develops spontaneously on exposure to ambient atmosphere which resists deformation and rupture of the resultant liquid particles. It is then of interest to develop methods for control of this oxide growth process. It is hypothesized here that functionalization of EGaIn nanoparticles with thiolated molecules could moderate oxide growth based on insights from the Cabrera-Mott oxidation model. To test this, the oxidation dynamics of several thiolated nanoparticle systems were tracked over time with X-ray photoelectron spectroscopy. These results demonstrate the ability to suppress gallium oxide growth by up to 30%. The oxide progressively matures over a 28 day period, terminating in different final thicknesses as a function of thiol selection. These results indicate not only that thiols moderate gallium oxide growth via competition with oxygen for surface sites but also that different thiols alter the thermodynamics of oxide growth through modification of the EGaIn work function.

Nanoparticles of nickel oxide: growth and organization on zinc-substituted anionic clay matrix by one-pot route at room temperature

NASA Astrophysics Data System (ADS)

Carja, Gabriela; Nakajima, Akira; Dranca, Cristian; Okada, Kiyoshi

2010-10-01

A room temperature nanocarving strategy is developed for the fabrication of nanoparticles of nickel oxide on zinc-substituted anionic clay matrix (Ni/ZnLDH). It is based on the growth and organization of nanoparticles of nickel oxide which occur during the structural reconstruction of the layered structure of the anionic clay in NiSO4 aqueous solution. No organic compounds are used during the fabrication. The described material was characterized by X-ray diffraction (XRD), IR spectroscopy (FTIR), transmission electron microscopy (TEM), field-emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) spectroscopy, and X-ray photoelectron spectroscopy (XPS). Results show that the nickel-clay nanoarchitecture consists of small nanoparticles of nickel oxide (average size 7 nm) deposited on the larger nanoparticles (average size 90 nm) of zinc-substituted clay. The optical properties of the new nickel-zinc formulation are studied by UV-Vis.

Fe 2O 3-Au hybrid nanoparticles for sensing applications via SERS analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Searles, Emily; Murph, Simona Hunyadi

Multifunctional iron oxide-gold hybrid nanostructures have been produced via solution chemistries and investigated for analyte detection. Gold nanoparticles of various shapes have been used for probing surface-enhanced Raman scattering (SERS) effects as they display unique optical properties in the visible-near IR region of the spectrum. When coupled with other nanoparticles, namely iron oxide nanoparticles, hybrid structures with increased functionality were produced. By exploiting their magnetic properties, nanogaps or “hot spots” were rationally created and evaluated for SERS enhancement studies. The “hot spots” were created by using a seeded reaction to increase the gold loading on the iron oxide support bymore » 43% by weight. SERS Nanomaterials were evaluated for their ability to promote surface-enhanced Raman scattering of a model analyte, 4-mercaptophenol. The data shows an enhancement effect of the model analyte on gold decorated iron oxide nanoparticles.« less

Liquid Plasma Synthesis of Carbon Coated Iron Oxide Particles

NASA Astrophysics Data System (ADS)

Uygun, Aysegul; Hershkowitz, Noah; Eren, Esin; Uygun, Emre; Celik Cogal, Gamze; Yurdabak Karaca, Gozde; Manolache, Sorin; Sundaram, Gunasekaran; Sadak, Omer; Oksuz, Lutfi

2017-10-01

Recently, magnetic metal or metal oxide nanoparticles encapsulated in carbon are important in biomedical applications. The relevant reason to study toxicity of the magnetic nanoparticles coated by carbon is that they have great potential to contribute to cancer treatment. In this work, the synthesis of iron oxide nano-particles coated by graphitic carbon shells using pulsed plasma in liquid method. Short duration of RF plasma discharge, low electrical energy and fast quenching of the surrounding media can let to synthesize various kinds of pure nanoparticles. Corresponding author: ayseguluygun@sdu.edu.tr, lutfioksuz@sdu.edu.tr.

Highly active thermally stable nanoporous gold catalyst

DOE Office of Scientific and Technical Information (OSTI.GOV)

Biener, Juergen; Wittstock, Arne; Biener, Monika M.

In one embodiment, a system includes a nanoporous gold structure and a plurality of oxide particles deposited on the nanoporous gold structure; the oxide particles are characterized by a crystalline phase. In another embodiment, a method includes depositing oxide nanoparticles on a nanoporous gold support to form an active structure and functionalizing the deposited oxide nanoparticles.

Intratumoral iron oxide nanoparticle hyperthermia and radiation cancer treatment

NASA Astrophysics Data System (ADS)

Hoopes, P. J.; Strawbridge, R. R.; Gibson, U. J.; Zeng, Q.; Pierce, Z. E.; Savellano, M.; Tate, J. A.; Ogden, J. A.; Baker, I.; Ivkov, R.; Foreman, A. R.

2007-02-01

The potential synergism and benefit of combined hyperthermia and radiation for cancer treatment is well established, but has yet to be optimized clinically. Specifically, the delivery of heat via external arrays /applicators or interstitial antennas has not demonstrated the spatial precision or specificity necessary to achieve appropriate a highly positive therapeutic ratio. Recently, antibody directed and possibly even non-antibody directed iron oxide nanoparticle hyperthermia has shown significant promise as a tumor treatment modality. Our studies are designed to determine the effects (safety and efficacy) of iron oxide nanoparticle hyperthermia and external beam radiation in a murine breast cancer model. Methods: MTG-B murine breast cancer cells (1 x 106) were implanted subcutaneous in 7 week-old female C3H/HeJ mice and grown to a treatment size of 150 mm3 +/- 50 mm3. Tumors were then injected locally with iron oxide nanoparticles and heated via an alternating magnetic field (AMF) generator operated at approximately 160 kHz and 400 - 550 Oe. Tumor growth was monitored daily using standard 3-D caliper measurement technique and formula. specific Mouse tumors were heated using a cooled, 36 mm diameter square copper tube induction coil which provided optimal heating in a 1 cm wide region in the center of the coil. Double dextran coated 80 nm iron oxide nanoparticles (Triton Biosystems) were used in all studies. Intra-tumor, peri-tumor and rectal (core body) temperatures were continually measured throughout the treatment period. Results: Preliminary in vivo nanoparticle-AMF hyperthermia (167 KHz and 400 or 550 Oe) studies demonstrated dose responsive cytotoxicity which enhanced the effects of external beam radiation. AMF associated eddy currents resulted in nonspecific temperature increases in exposed tissues which did not contain nanoparticles, however these effects were minor and not injurious to the mice. These studies also suggest that iron oxide nanoparticle hyperthermia is more effective than non-nanoparticle tumor heating techniques when similar thermal doses are applied. Initial electron and light microscopy studies of iron oxide nanoparticle and AMF exposed tumor cells show a rapid uptake of particles and acute cytotoxicity following AMF exposure.

Advanced Polymer Systems for Defence Applications: Power Generation, Protection and Sensing

DTIC Science & Technology

2014-05-01

oxide nanoparticles synthesized via non-sol-gel methods, e.g., via a flame process; and, (d) Amine sensors based on silver nanoparticle- doped ...Hongmin Chen, Guodong Chen, Xiaohong Gu, James L. Lee, E. E. Abdel-Hady, Y. C. Jean. Free Volumes, Glass Transitions, and Cross-Links in Zinc Oxide ...properties in a system of zinc oxide (ZnO) nanoparticles (20 nm) dispersed in waterborne polyurethane (WBPU) were measured using positron annihilation

Effect of solvents on morphology, magnetic and dielectric properties of (α-Fe2O3@SiO2) core-shell nanoparticles.

PubMed

Joshi, Deepika P; Pant, Geeta; Arora, Neha; Nainwal, Seema

2017-02-01

Present work describes the formation of α-Fe 2 O 3 @SiO 2 core shell structure by systematic layer by layer deposition of silica shell on core iron oxide nanoparticles prepared via various solvents. Sol-gel method has been used to synthesize magnetic core and the dielectric shell. The average crystallite size of iron oxide nanoparticles was calculated ∼20 nm by X-ray diffraction pattern. Morphological study by scanning electron microscopy revealed that the core-shell nanoparticles were spherical in shape and the average size of nanoparticles increased by varying solvent from methanol to ethanol to isopropanol due to different chemical structure and nature of the solvents. It was also observed that the particles prepared by solvent ethanol were more regular and homogeneous as compared to other solvents. Magnetic measurements showed the weak ferromagnetic behaviour of both core α-Fe 2 O 3 and silica-coated iron oxide nanoparticles which remained same irrespective of the solvent chosen. However, magnetization showed dependency on the types of solvent chosen due to the variation in shell thickness. At room temperature, dielectric constant and dielectric loss of silica nanoparticles for all the solvents showed decrement with the increment in frequency. Decrement in the value of dielectric constant and increment in dielectric loss was observed for silica coated iron oxide nanoparticles in comparison of pure silica, due to the presence of metallic core. Homogeneous and regular silica layer prepared by using ethanol as a solvent could serve as protecting layer to shield the magnetic behaviour of iron oxide nanoparticles as well as to provide better thermal insulation over pure α-Fe 2 O 3 nanoparticles.

Depositing laser-generated nanoparticles on powders for additive manufacturing of oxide dispersed strengthened alloy parts via laser metal deposition

NASA Astrophysics Data System (ADS)

Streubel, René; Wilms, Markus B.; Doñate-Buendía, Carlos; Weisheit, Andreas; Barcikowski, Stephan; Henrich Schleifenbaum, Johannes; Gökce, Bilal

2018-04-01

We present a novel route for the adsorption of pulsed laser-dispersed nanoparticles onto metal powders in aqueous solution without using any binders or surfactants. By electrostatic interaction, we deposit Y2O3 nanoparticles onto iron-chromium based powders and obtain a high dispersion of nano-sized particles on the metallic powders. Within the additively manufactured component, we show that the particle spacing of the oxide inclusion can be adjusted by the initial mass fraction of the adsorbed Y2O3 particles on the micropowder. Thus, our procedure constitutes a robust route for additive manufacturing of oxide dispersion-strengthened alloys via oxide nanoparticles supported on steel micropowders.

Gold nanotriangles decorated with superparamagnetic iron oxide nanoparticles: a compositional and microstructural study

DOE PAGES

Hachtel, J. A.; Yu, S.; Lupini, A. R.; ...

2016-03-11

The combination of iron oxide and gold in a single nanoparticle results in both magnetic and plasmonic properties that can stimulate novel applications in bio-sensing, medical imaging, or therapeutics. Microwave assisted heating allows the fabrication of multi-component, multi-functional nanostructures by promoting selective heating at desired sites. Recently, we reported a microwave-assisted polyol route yielding gold nanotriangles decorated with iron oxide nanoparticles. Here, we present an in-depth microstructural and compositional characterization of the system by using scanning transmission electron microscopy (STEM) and electron energy loss (EELS) spectroscopy. A method to remove the iron oxide nanoparticles from the gold nanocrystals and somemore » insights on crystal nucleation and growth mechanisms are also provided.« less

Exchange bias of Ni nanoparticles embedded in an antiferromagnetic IrMn matrix.

PubMed

Kuerbanjiang, Balati; Wiedwald, Ulf; Haering, Felix; Biskupek, Johannes; Kaiser, Ute; Ziemann, Paul; Herr, Ulrich

2013-11-15

The magnetic properties of Ni nanoparticles (Ni-NPs) embedded in an antiferromagnetic IrMn matrix were investigated. The Ni-NPs of 8.4 nm mean diameter were synthesized by inert gas aggregation. In a second processing step, the Ni-NPs were in situ embedded in IrMn films or SiOx films under ultrahigh vacuum (UHV) conditions. Findings showed that Ni-NPs embedded in IrMn have an exchange bias field HEB = 821 Oe at 10 K, and 50 Oe at 300 K. The extracted value of the exchange energy density is 0.06 mJ m(-2) at 10 K, which is in good accordance with the results from multilayered thin film systems. The Ni-NPs embedded in SiOx did not show exchange bias. As expected for this particle size, they are superparamagnetic at T = 300 K. A direct comparison of the Ni-NPs embedded in IrMn or SiOx reveals an increase of the blocking temperature from 210 K to around 400 K. The coercivity of the Ni-NPs exchange coupled to the IrMn matrix at 10 K is 8 times larger than the value for Ni-NPs embedded in SiOx. We studied time-dependent remanent magnetization at different temperatures. The relaxation behavior is described by a magnetic viscosity model which reflects a rather flat distribution of energy barriers. Furthermore, we investigated the effects of different field cooling processes on the magnetic properties of the embedded Ni-NPs. Exchange bias values fit to model calculations which correlate the contribution of the antiferromagnetic IrMn matrix to its grain size.

Nonenzymatic glucose sensor based on renewable electrospun Ni nanoparticle-loaded carbon nanofiber paste electrode.

PubMed

Liu, Yang; Teng, Hong; Hou, Haoqing; You, Tianyan

2009-07-15

A novel nonenzymatic glucose sensor was developed based on the renewable Ni nanoparticle-loaded carbon nanofiber paste (NiCFP) electrode. The NiCF nanocomposite was prepared by combination of electrospinning technique with thermal treatment method. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images showed that large amounts of spherical nanoparticles were well dispersed on the surface or embedded in the carbon nanofibers. And the nanoparticles were composed of Ni and NiO, as revealed by energy dispersive X-ray spectroscopy (EDX) and X-ray powder diffraction (XRD). In application to nonenzymatic glucose determination, the renewable NiCFP electrodes, which were constructed by simply mixing the electrospun nanocomposite with mineral oil, exhibited strong and fast amperometric response without being poisoned by chloride ions. Low detection limit of 1 microM with wide linear range from 2 microM to 2.5 mM (R=0.9997) could be obtained. The current response of the proposed glucose sensor was highly sensitive and stable, attributing to the electrocatalytic performance of the firmly embedded Ni nanoparticles as well as the chemical inertness of the carbon-based electrode. The good analytical performance, low cost and straightforward preparation method made this novel electrode material promising for the development of effective glucose sensor.

Toxicity of food-relevant nanoparticles in intestinal epithelial models

NASA Astrophysics Data System (ADS)

McCracken, Christie

Nanoparticles are increasingly being incorporated into common consumer products, including in foods and food packaging, for their unique properties at the nanoscale. Food-grade silica and titania are used as anti-caking and whitening agents, respectively, and these particle size distributions are composed of approximately one-third nanoparticles. Zinc oxide and silver nanoparticles can be used for their antimicrobial properties. However, little is known about the interactions of nanoparticles in the body upon ingestion. This study was performed to investigate the role of nanoparticle characteristics including surface chemistry, dissolution, and material type on toxicity to the intestinal epithelium. Only mild acute toxicity of zinc oxide nanoparticles was observed after 24-hour treatment of intestinal epithelial C2BBe1 cells based on the results of toxicity assays measuring necrosis, apoptosis, membrane damage, and mitochondrial activity. Silica and titanium dioxide nanoparticles were not observed to be toxic although all nanoparticles were internalized by cells. In vitro digestion of nanoparticles in solutions representing the stomach and intestines prior to treatment of cells did not alter nanoparticle toxicity. Long-term repeated treatment of cells weekly for 24 hours with nanoparticles did not change nanoparticle cytotoxicity or the growth rate of the treated cell populations. Thus, silica, titanium dioxide, and zinc oxide nanoparticles were found to induce little toxicity in intestinal epithelial cells. Fluorescent silica nanoparticles were synthesized as a model for silica used in foods that could be tracked in vitro and in vivo. To maintain an exterior of pure silica, a silica shell was hydrolyzed around a core particle of quantum dots or a fluorescent dye electrostatically associated with a commercial silica particle. The quantum dots used were optimized from a previously reported microwave quantum dot synthesis to a quantum yield of 40%. Characterization of the silica particles showed that the surface properties resembled pure silica. These particles were able to be detected in vitro as well as in vivo after oral administration of nanoparticles to mice by gavage. After four daily administrations, nanoparticles were detected by fluorescence confocal microscopy in intestines as well as liver, kidney, spleen, lung, and brain. Thus, silica nanoparticles were able to traverse the intestinal epithelium. Further investigation is needed to determine nanoparticle accumulation and potential functional consequences throughout the body. Silver nanoparticles were particularly toxic to proliferating (subconfluent) C2BBe1 cells plated at low density, inducing 15% necrosis and a 76% decrease in mitochondrial activity. Silver nanoparticle treatment induced oxidative stress in cells based on increased GSH/GSSG ratios. In addition, silver nanoparticles induced G2/M phase cell cycle arrest and inhibited cell proliferation at doses forty times lower than those at which silica, titanium dioxide, and zinc oxide nanoparticles had inhibitory effects. Silver nanoparticles subjected to in vitro digestion before cell exposure required higher doses to induce toxicity, likely due to slower dissolution because of greater surface species adsorption. Silver nanoparticles did not cause toxicity or oxidative stress in confluent (stationary) cells. Thus, upon ingestion, silver nanoparticles may be especially toxic to proliferating stem cells in intestinal crypts, particularly in disease states with a compromised epithelium.

Optical control of capacitance in a metal-insulator-semiconductor diode with embedded metal nanoparticles

NASA Astrophysics Data System (ADS)

Mikhelashvili, V.; Ankonina, G.; Kauffmann, Y.; Atiya, G.; Kaplan, W. D.; Padmanabhan, R.; Eisenstein, G.

2017-06-01

This paper describes a metal-insulator-semiconductor (MIS) capacitor with flat capacitance voltage characteristics and a small quadratic voltage capacitance coefficient. The device characteristics resemble a metal-insulator-metal diode except that here the capacitance depends on illumination and exhibits a strong frequency dispersion. The device incorporates Fe nanoparticles (NPs), mixed with SrF2, which are embedded in an insulator stack of SiO2 and HfO2. Positively charged Fe ions induce dipole type traps with an electronic polarization that is enhanced by photogenerated carriers injected from the substrate and/or by inter nanoparticle exchange of carriers. The obtained characteristics are compared with those of five other MIS structures: two based on Fe NPs, one with and the other without SrF2 sublayers. Additionally, devices contain Co NPs embedded in SrF2 sublayers, and finally, two structures have no NPs, with one based on a stack of SiO2 and HfO2 and the other which also includes SrF2. Only structures containing Fe NPs, which are incorporated into SrF2, yield a voltage independent capacitance, the level of which can be changed by illumination. These properties are essential in radio frequency/analog mixed signal applications.

TOPO-capped silver selenide nanoparticles and their incorporation into polymer nanofibers using electrospinning technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

More, D.S.; Moloto, M.J., E-mail: makwenam@vut.ac.za; Moloto, N.

Highlights: • Ag{sub 2}Se nanoparticles produced spherical particles with sizes 12 nm (180 °C) and 27 nm (200 °C). • Higher temperature produced increased particle size (∼75 nm) and changed in shape. • Ag{sub 2}Se nanoparticles (0.2–0.6%) added into PVP (35–45%) to yield reduced fiber beading. • Polymer nanofibers electrospun at 11–20 kV produced fiber diameters of 425–461 nm. • Optical properties in the fibers were observed due to the Ag{sub 2}Se nanoparticles loaded. - Abstract: Electrospinning is the most common technique for fabricating polymer fibers as well as nanoparticles embedded polymer fibers. Silver selenide nanoparticles were synthesized using tri-n-octylphosphinemore » (TOP) as solvent and tri-n-octylphosphine oxide (TOPO) as capping environment. Silver selenide was prepared by reacting silver nitrate and selenium with tri-n-octylphosphine (TOP) to form TOP–Ag and TOP–Se solutions. Both absorption and emission spectra signify the formation of nanoparticles as well as the TEM which revealed spherical particles with an average particle size of 22 nm. The polymer, PVP used was prepared at concentrations ranging from (35 to 45 wt%) and the TOPO-capped silver selenide nanoparticles (0.2 and 0.6 wt%) were incorporated into them and electrospun by varying the voltage from 11 to 20 kV. The SEM images of the Ag{sub 2}Se/PVP composite fibers revealed the fibers of diameters with average values of 425 and 461 nm. The X-ray diffraction results show peaks which were identified due to α-Ag{sub 2}Se body centered cubic compound. The sharp peak observed for all the samples at 2θ = 44.5 suggest the presence of Ag in the face centered cubic which can be attributed to higher concentration of silver nitrate used with molar ratio of selenium to silver and the abundance of silver in the silver selenide crystal. Fourier transform infrared spectroscopy, thermogravimetric analysis (TGA) and ultraviolet–visible spectroscopy were used to characterize the structure of the PVP/Ag{sub 2}Se composite fibers.« less