X-ray excited luminescence of polystyrene composites loaded with SrF{sub 2} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Demkiv, T.M.; Halyatkin, O.O.; Vistovskyy, V.V. [Ivan Franko National University of Lviv, 8a Kyryla i Mefodiya St., 79005 Lviv (Ukraine); Hevyk, V.B. [Ivano-Frankivsk National Technical University of Oil and Gas, 15 Karpatska St., 76019 Ivano-Frankivsk (Ukraine); Yakibchuk, P.M. [Ivan Franko National University of Lviv, 8a Kyryla i Mefodiya St., 79005 Lviv (Ukraine); Gektin, A.V. [Institute for Scintillation Materials, NAS of Ukraine, 60 Lenina Ave, 61001 Kharkiv (Ukraine); Voloshinovskii, A.S. [Ivan Franko National University of Lviv, 8a Kyryla i Mefodiya St., 79005 Lviv (Ukraine)

2017-03-01

The polystyrene film nanocomposites of 0.3 mm thickness with embedded SrF{sub 2} nanoparticles up to 40 wt% have been synthesized. The luminescent and kinetic properties of the polystyrene composites with embedded SrF{sub 2} nanoparticles upon the pulse X-ray excitation have been investigated. The luminescence intensity of the pure polystyrene scintillator film significantly increases when it is loaded with the inorganic SrF{sub 2} nanoparticles. The film nanocomposites show fast (∼2.8 ns) and slow (∼700 ns) luminescence decay components typical for a luminescence of polystyrene activators (p-Terphenyl and POPOP) and SrF{sub 2} nanoparticles, respectively. It is revealed that the fast decay luminescence component of the polystyrene composites is caused by the excitation of polystyrene by the photoelectrons escaped from the nanoparticles due to photoeffect, and the slow component is caused by reabsorption of the self-trapped exciton luminescence of SrF{sub 2} nanoparticles by polystyrene.

Laser ablation synthesis of monodispersed magnetic alloy nanoparticles

International Nuclear Information System (INIS)

Seto, Takafumi; Koga, Kenji; Akinaga, Hiroyuki; Takano, Fumiyoshi; Orii, Takaaki; Hirasawa, Makoto

2006-01-01

Monodispersed CoPt alloy nanoparticles were synthesized by a pulsed laser ablation (PLA) technique coupled with a low-pressure operating differential mobility analyzer (LP-DMA). The CoPt alloy nanoparticles were generated by laser ablating a solid Co-Pt target. In CoPt alloy nanoparticles synthesized from a target with a Co composition of 75 at%, the nanoparticle surfaces were covered by an oxide layer and exhibited a core-shell structure. In contrast, no shell was observed in particles generated from a target with a Co:Pt ratio of 50:50 at%. According to an EDX analysis, the compositions of the individual nanoparticles were almost the same as that of the target material. Finally, the magnetic hysteresis loops of the CoPt alloy nanoparticles exhibited ferromagnetism

Laser ablation synthesis of monodispersed magnetic alloy nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Seto, Takafumi, E-mail: t.seto@aist.go.jp; Koga, Kenji; Akinaga, Hiroyuki; Takano, Fumiyoshi; Orii, Takaaki; Hirasawa, Makoto [National Institute of Advanced Industrial Science and Technology (AIST), Research Consortium for Synthetic Nano-Function Materials Project (SYNAF) (Japan)

2006-08-15

Monodispersed CoPt alloy nanoparticles were synthesized by a pulsed laser ablation (PLA) technique coupled with a low-pressure operating differential mobility analyzer (LP-DMA). The CoPt alloy nanoparticles were generated by laser ablating a solid Co-Pt target. In CoPt alloy nanoparticles synthesized from a target with a Co composition of 75 at%, the nanoparticle surfaces were covered by an oxide layer and exhibited a core-shell structure. In contrast, no shell was observed in particles generated from a target with a Co:Pt ratio of 50:50 at%. According to an EDX analysis, the compositions of the individual nanoparticles were almost the same as that of the target material. Finally, the magnetic hysteresis loops of the CoPt alloy nanoparticles exhibited ferromagnetism.

Synthesis of monodisperse silver nanoparticles for ink-jet printed flexible electronics

Energy Technology Data Exchange (ETDEWEB)

Zhang Zhiliang; Zhang Xingye; Xin Zhiqing; Deng Mengmeng; Wen Yongqiang; Song Yanlin, E-mail: zhangxy@iccas.ac.cn, E-mail: ylsong@iccas.ac.cn [Beijing National Laboratory for Molecular Sciences (BNLMS), Key Lab of Organic Solids, Laboratory of New Materials, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)

2011-10-21

In this study, monodisperse silver nanoparticles were synthesized with a new reduction system consisting of adipoyl hydrazide and dextrose at ambient temperature. By this facile and rapid approach, high concentration monodisperse silver nanoparticles were obtained on a large scale at low protectant/AgNO{sub 3} mass ratio which was highly beneficial to low cost and high conductivity. Based on the synthesized monodisperse silver nanoparticles, conductive inks were prepared with water, ethanol and ethylene glycol as solvents, and were expected to be more environmentally friendly. A series of electrocircuits were fabricated by ink-jet printing silver nanoparticle ink on paper substrate with a commercial printer, and they had low resistivity in the range of 9.18 x 10{sup -8}-8.76 x 10{sup -8} {Omega} m after thermal treatment at 160 {sup 0}C for 30 min, which was about five times that of bulk silver (1.586 x 10{sup -8} {Omega} m). Moreover, a radio frequency identification (RFID) antenna was fabricated by ink-jet printing, and 6 m wireless identification was realized after an Alien higgs-3 chip was mounted on the printed antenna by the flip-chip method. These flexible electrocircuits produced by ink-jet printing would have enormous potential for low cost electrodes and sensor devices.

Synthesis of monodisperse silver nanoparticles for ink-jet printed flexible electronics

International Nuclear Information System (INIS)

Zhang Zhiliang; Zhang Xingye; Xin Zhiqing; Deng Mengmeng; Wen Yongqiang; Song Yanlin

2011-01-01

In this study, monodisperse silver nanoparticles were synthesized with a new reduction system consisting of adipoyl hydrazide and dextrose at ambient temperature. By this facile and rapid approach, high concentration monodisperse silver nanoparticles were obtained on a large scale at low protectant/AgNO 3 mass ratio which was highly beneficial to low cost and high conductivity. Based on the synthesized monodisperse silver nanoparticles, conductive inks were prepared with water, ethanol and ethylene glycol as solvents, and were expected to be more environmentally friendly. A series of electrocircuits were fabricated by ink-jet printing silver nanoparticle ink on paper substrate with a commercial printer, and they had low resistivity in the range of 9.18 x 10 -8 -8.76 x 10 -8 Ω m after thermal treatment at 160 0 C for 30 min, which was about five times that of bulk silver (1.586 x 10 -8 Ω m). Moreover, a radio frequency identification (RFID) antenna was fabricated by ink-jet printing, and 6 m wireless identification was realized after an Alien higgs-3 chip was mounted on the printed antenna by the flip-chip method. These flexible electrocircuits produced by ink-jet printing would have enormous potential for low cost electrodes and sensor devices.

Monodisperse Silver Nanoparticles Synthesized by a Microwave-Assisted Method

International Nuclear Information System (INIS)

Shao-Peng, Zhu; Shao-Chun, Tang; Xiang-Kang, Meng

2009-01-01

Silver nanoparticles with an average size of about 20 nm are synthesized in a colloidal solution with the aid of microwave irradiation. Neither additional reductant nor stabilizer is required in this microwave-assisted method. The color of the colloidal solution is found to be dark green, different from the characteristic yellow of silver colloidal solutions. The silver nanoparticles in the colloidal solution have a narrow size distribution and large yield quantity. UV-visible absorption spectroscopy analysis reveals that the as-synthesized monodisperse silver nanoparticles have exceptional optical properties. Raman spectroscopy measurements demonstrate that these silver nanoparticles exhibit a notable surface-enhanced Raman scattering ability. (cross-disciplinary physics and related areas of science and technology)

Synthesis of raspberry-like monodisperse magnetic hollow hybrid nanospheres by coating polystyrene template with Fe(3)O(4)@SiO(2) particles.

Science.gov (United States)

Wang, Chunlei; Yan, Juntao; Cui, Xuejun; Wang, Hongyan

2011-02-01

In this paper, we present a novel method for the preparation of raspberry-like monodisperse magnetic hollow hybrid nanospheres with γ-Fe(2)O(3)@SiO(2) particles as the outer shell. PS@Fe(3)O(4)@SiO(2) composite nanoparticles were successfully prepared on the principle of the electrostatic interaction between negatively charged silica and positively charged polystyrene, and then raspberry-like magnetic hollow hybrid nanospheres with large cavities were achieved by means of calcinations, simultaneously, the magnetite (Fe(3)O(4)) was transformed into maghemite (γ-Fe(2)O(3)). Transmission electron microscopy (TEM) demonstrated that the obtained magnetic hollow silica nanospheres with the perfect spherical profile were well monodisperse and uniform with the mean size of 253nm. The Fourier transform infrared (FTIR) spectrometry, energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) provided the sufficient evidences for the presence of Fe(3)O(4) in the silica shell. Moreover, the magnetic hollow silica nanospheres possessed a characteristic of superparamagnetic with saturation magnetization value of about 7.84emu/g by the magnetization curve measurement. In addition, the nitrogen adsorption-desorption measurement exhibited that the pore size, BET surface area, pore volume of magnetic hollow silica nanospheres were 3.5-5.5nm, 307m(2)g(-1) and 1.33cm(3)g(-1), respectively. Therefore, the magnetic hollow nanospheres possess a promising future in controlled drug delivery and targeted drug applications. Copyright © 2010 Elsevier Inc. All rights reserved.

A novel approach for preparation of micrometer-sized, monodisperse dimple and hemispherical polystyrene particles.

Science.gov (United States)

Tanaka, Takuya; Komatsu, Yoshifumi; Fujibayashi, Teruhisa; Minami, Hideto; Okubo, Masayoshi

2010-03-16

Micrometer-sized, monodisperse dimple and hemispherical polystyrene (PS) particles were successfully prepared by heating (55-70 degrees C) of spherical PS particles dispersed in methanol/water media (40/60 to 80/20, w/w) in the presence of decane droplets, and subsequent cooling down to room temperature. Decane was absorbed by the PS particles during the heating process. Decane-absorbed PS particles phase-separated into PS and decane phases in the inside during the cooling process, and eventually dimple and/or hemispherical particles were formed by removal of the decane phase from phase-separated PS/decane particles by evaporation. The size of the dimple, which is determined by the volume of decane phase-separated from decane-absorbed PS particles during the cooling process, increased with increases in the heating temperature and the methanol content.

Assembly of Fe3O4 nanoparticles on SiO2 monodisperse spheres

Indian Academy of Sciences (India)

Assembly of Fe3O4 nanoparticles on SiO2 monodisperse spheres. K C BARICK and D BAHADUR*. Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay,. Mumbai 400 076, India. Abstract. The assembly of superparamagnetic Fe3O4 nanoparticles on submicroscopic SiO2 ...

Effect of molecular weight distribution on e-beam exposure properties of polystyrene

International Nuclear Information System (INIS)

Dey, Ripon Kumar; Cui Bo

2013-01-01

Polystyrene is a negative electron beam resist whose exposure properties can be tuned simply by using different molecular weights (Mw). Most previous studies have used monodisperse polystyrene with a polydispersity index (PDI) of less than 1.1 in order to avoid any uncertainties. Here we show that despite the fact that polystyrene’s sensitivity is inversely proportional to its Mw, no noticeable effect of very broad molecular weight distribution on sensitivity, contrast and achievable resolution is observed. It is thus unnecessary to use the costly monodisperse polystyrene for electron beam lithography. Since the polydispersity is unknown for general purpose polystyrene, we simulated a high PDI polystyrene by mixing in a 1:1 weight ratio two polystyrene samples with Mw of 170 and 900 kg mol −1 for the high Mw range, and 2.5 and 13 kg mol −1 for the low Mw range. The exposure property of the mixture resembles that of a monodisperse polystyrene with similar number averaged molecular weight (Mn)-bar, which indicates that it is (Mn)-bar rather than (Mw)-bar (weight averaged molecular weight) that dominates the exposure properties of polystyrene resist. This also implies that polystyrene of a certain molecular weight can be simulated by a mixture of two polystyrenes having different molecular weights. (paper)

Fabrication of monodisperse magnetic nanoparticles released in solution using a block copolymer template

Science.gov (United States)

Morcrette, Mélissa; Ortiz, Guillermo; Tallegas, Salomé; Joisten, Hélène; Tiron, Raluca; Baron, Thierry; Hou, Yanxia; Lequien, Stéphane; Bsiesy, Ahmad; Dieny, Bernard

2017-07-01

This paper describes a fabrication process of monodisperse magnetic nanoparticles released in solution, based on combined ‘top-down’ and ‘bottom-up’ approaches. The process involves the use of a self-assembled PS-PMMA block copolymer formed on a sacrificial layer. Such an approach was so far mostly explored for the preparation of patterned magnetic media for ultrahigh density magnetic storage. It is here extended to the preparation of released monodisperse nanoparticles for biomedical applications. A special sacrificial layer had to be developed compatible with the copolymer self-organization. The resulting nanoparticles exhibit very narrow size dispersion (≈7%) and can be good candidates as contrast agents for medical imaging i.e. magnetic resonance imaging or magnetic particle imaging. The approach provides a great freedom in the choice of the particles shapes and compositions. In particular, they can be made of biocompatible magnetic material.

Fabrication of monodisperse magnetic nanoparticles released in solution using a block copolymer template

International Nuclear Information System (INIS)

Morcrette, Mélissa; Ortiz, Guillermo; Joisten, Hélène; Dieny, Bernard; Tallegas, Salomé; Baron, Thierry; Bsiesy, Ahmad; Tiron, Raluca; Hou, Yanxia; Lequien, Stéphane

2017-01-01

This paper describes a fabrication process of monodisperse magnetic nanoparticles released in solution, based on combined ‘top-down’ and ‘bottom-up’ approaches. The process involves the use of a self-assembled PS-PMMA block copolymer formed on a sacrificial layer. Such an approach was so far mostly explored for the preparation of patterned magnetic media for ultrahigh density magnetic storage. It is here extended to the preparation of released monodisperse nanoparticles for biomedical applications. A special sacrificial layer had to be developed compatible with the copolymer self-organization. The resulting nanoparticles exhibit very narrow size dispersion (≈7%) and can be good candidates as contrast agents for medical imaging i.e. magnetic resonance imaging or magnetic particle imaging. The approach provides a great freedom in the choice of the particles shapes and compositions. In particular, they can be made of biocompatible magnetic material. (paper)

Environmentally friendly synthesis of highly monodisperse biocompatible gold nanoparticles with urchin-like shape.

Science.gov (United States)

Lu, Lehui; Ai, Kelong; Ozaki, Yukihiro

2008-02-05

We report a facile and environmentally friendly strategy for high-yield synthesis of highly monodisperse gold nanoparticles with urchin-like shape. A simple protein, gelatin, was first used for the control over shape and orientation of the gold nanoparticles. These nanoparticles, ready to use for biological systems, are promising in the optical imaging-based disease diagnostics and therapy because of their tunable surface plasmon resonance (SPR) and excellent surface-enhanced Raman scattering (SERS) activity.

Tuning the wettability of calcite cubes by varying the sizes of the polystyrene nanoparticles attached to their surfaces

International Nuclear Information System (INIS)

He Yongjun; Li Tanliang; Yu Xiangyang; Zhao Shiyong; Lu Jianhua; He Jia

2007-01-01

The wettability of calcite cubes was tuned by varying the sizes of the polystyrene nanoparticles attached to their surfaces via a dispersion polymerization. The products were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersion spectrum (EDS) and Fourier transformation infrared spectrum (FTIR). The results showed that the hydrophobicity of the calcite cubes was enhanced with the increase of the size of the polystyrene nanoparticles attached. Using polystyrene nanoparticle-attached calcite cubes (PNACC) as emulsifiers, stable water-in-tricaprylin Pickering emulsions were produced. By gelling the water droplets of the Pickering emulsions, the hierarchical structures of polystyrene nanoparticle-attached calcite cube-armored microspheres were obtained. The polystyrene nanoparticle-attached calcite cubes were expected to have novel surface properties similar neither to traditional Pickering particles, nor to macroscopically asymmetrical Janus particles

Altered behavior, physiology, and metabolism in fish exposed to polystyrene nanoparticles

DEFF Research Database (Denmark)

Mattsson, Karin; Ekvall, Mikael T; Hansson, Lars-Anders

2015-01-01

that enter natural ecosystems, such as oceans and lakes, is increasing, and degradation of the disposed plastics produces smaller particles toward the nano scale. Therefore, it is of utmost importance to gain knowledge about how plastic nanoparticles enter and affect living organisms. Here we have...... administered 24 and 27 nm polystyrene nanoparticles to fish through an aquatic food chain, from algae through Daphnia, and studied the effects on behavior and metabolism. We found severe effects on feeding and shoaling behavior as well as metabolism of the fish; hence, we conclude that polystyrene...

Polystyrene Microbeads by Dispersion Polymerization: Effect of Solvent on Particle Morphology

Directory of Open Access Journals (Sweden)

Lei Jinhua

2014-01-01

Full Text Available Polystyrene microspheres (PS were synthesized by dispersion polymerization in ethanol/2-Methoxyethanol (EtOH/EGME blend solvent using styrene (St as monomer, azobisisobutyronitrile (AIBN as initiator, and PVP (polyvinylpyrrolidone K-30 as stabilizer. The typical recipe of dispersion polymerization is as follows: St/Solvent/AIBN/PVP = 10 g/88 g/0.1 g/2 g. The morphology of polystyrene microspheres was characterized by the scanning electron microscopy (SEM and the molecular weights of PS particles were measured by the Ubbelohde viscometer method. The effect of ethanol content in the blend solvent on the morphology and molecular weight of polystyrene was studied. We found that the size of polystyrene microspheres increased and the molecular weight of polystyrene microspheres decreased with the decreasing of the ethanol content in the blend solvent from 100 wt% to 0 wt%. What is more, the size monodispersity of polystyrene microspheres was quite good when the pure ethanol or pure 2-Methoxyethanol was used; however when the blend ethanol/2-Methoxyethanol solvent was used, the polystyrene microspheres became polydisperse. We further found that the monodispersity of polystyrene microspheres can be significantly improved by adding a small amount of water into the blend solvent; the particles became monodisperse when the content of water in the blend solvent was up to 2 wt%.

Extracellular biosynthesis of monodispersed gold nanoparticles by a SAM capping route

Science.gov (United States)

Wen, Li; Lin, Zhonghua; Gu, Pingying; Zhou, Jianzhang; Yao, Bingxing; Chen, Guoliang; Fu, Jinkun

2009-02-01

Monodispersed gold nanoparticles capped with a self-assembled monolayer of dodecanethiol were biosynthesized extracellularly by an efficient, simple, and environmental friendly procedure, which involved the use of Bacillus megatherium D01 as the reducing agent and the use of dodecanethiol as the capping ligand at 26 °C. The kinetics of gold nanoparticle formation was followed by transmission electron microscope (TEM) and UV-vis spectroscopy. It was shown that reaction time was an important parameter in controlling the morphology of gold nanoparticles. The effect of thiol on the shape, size, and dispersity of gold nanoparticles was also studied. The results showed that the presence of thiol during the biosynthesis could induce the formation of small size gold nanoparticles (gold nanoparticles capped with thiol of 1.9 ± 0.8 nm size were formed by using Bacillus megatherium D01.

Polystyrene nanoparticles facilitate the internalization of impermeable biomolecules in non-tumour and tumour cells from colon epithelium

Energy Technology Data Exchange (ETDEWEB)

Cabeza, Laura [University of Granada, Department of Human Anatomy and Embryology, Institute of Biopathology and Regenerative Medicine (IBIMER) (Spain); Cano-Cortés, Victoria; Rodríguez, María J. [University of Granada, Department of Pharmaceutical and Organic Chemistry (Spain); Vélez, Celia; Melguizo, Consolación, E-mail: melguizo@ugr.es [University of Granada, Department of Human Anatomy and Embryology, Institute of Biopathology and Regenerative Medicine (IBIMER) (Spain); Sánchez-Martín, Rosario M., E-mail: rmsanchez@ugr.es [University of Granada, Department of Pharmaceutical and Organic Chemistry (Spain); Prados, Jose [University of Granada, Department of Human Anatomy and Embryology, Institute of Biopathology and Regenerative Medicine (IBIMER) (Spain)

2015-01-15

Advanced colon cancer has a poor prognosis due to the limited effectiveness of current chemotherapies. Treatment failures may be avoided by the utilization of nanoparticles, which can enhance the effects of antitumor drugs, reduce their side effects and increase their directionality. Polystyrene nanoparticles have shown high biocompatibility and appropriate physicochemical properties and may represent a novel and more effective approach against colon cancer. In the present study, polystyrene nanoparticles were synthesized and fluorescently labelled, analyzing their cell internalization, intracellular localization and capacity to release transported molecules in tumour and non-tumour human colon cell lines (T84 and CCD-18). Flow cytometry and fluorescence microscopy studies demonstrated that polystyrene nanoparticles are an effective vehicle for the intracellular delivery of small molecules into colon epithelium cells. The percentage cell uptake was around 100 % in both T84 and CCD-18 cell lines after only 24 h of exposure and was cell confluence-independent. The polystyrene nanoparticles showed no cytotoxicity in either colon cell line. It was found that small molecules can be efficiently delivered into colon cells by using a disulphide bridge as release strategy. Analysis of the influence of the functionalization of the polystyrene nanoparticles surface on the internalization efficiency revealed some morphological changes in these cells. These results demonstrate that polystyrene nanoparticles may improve the transport of biomolecules into colon cells which could have a potential application in chemotherapeutic treatment against colon cancer.

Polystyrene nanoparticles facilitate the internalization of impermeable biomolecules in non-tumour and tumour cells from colon epithelium

International Nuclear Information System (INIS)

Cabeza, Laura; Cano-Cortés, Victoria; Rodríguez, María J.; Vélez, Celia; Melguizo, Consolación; Sánchez-Martín, Rosario M.; Prados, Jose

2015-01-01

Advanced colon cancer has a poor prognosis due to the limited effectiveness of current chemotherapies. Treatment failures may be avoided by the utilization of nanoparticles, which can enhance the effects of antitumor drugs, reduce their side effects and increase their directionality. Polystyrene nanoparticles have shown high biocompatibility and appropriate physicochemical properties and may represent a novel and more effective approach against colon cancer. In the present study, polystyrene nanoparticles were synthesized and fluorescently labelled, analyzing their cell internalization, intracellular localization and capacity to release transported molecules in tumour and non-tumour human colon cell lines (T84 and CCD-18). Flow cytometry and fluorescence microscopy studies demonstrated that polystyrene nanoparticles are an effective vehicle for the intracellular delivery of small molecules into colon epithelium cells. The percentage cell uptake was around 100 % in both T84 and CCD-18 cell lines after only 24 h of exposure and was cell confluence-independent. The polystyrene nanoparticles showed no cytotoxicity in either colon cell line. It was found that small molecules can be efficiently delivered into colon cells by using a disulphide bridge as release strategy. Analysis of the influence of the functionalization of the polystyrene nanoparticles surface on the internalization efficiency revealed some morphological changes in these cells. These results demonstrate that polystyrene nanoparticles may improve the transport of biomolecules into colon cells which could have a potential application in chemotherapeutic treatment against colon cancer

Monodisperse Platinum and Rhodium Nanoparticles as Model Heterogeneous Catalysts

Energy Technology Data Exchange (ETDEWEB)

Grass, Michael Edward [Univ. of California, Berkeley, CA (United States)

2008-09-01

Model heterogeneous catalysts have been synthesized and studied to better understand how the surface structure of noble metal nanoparticles affects catalytic performance. In this project, monodisperse rhodium and platinum nanoparticles of controlled size and shape have been synthesized by solution phase polyol reduction, stabilized by polyvinylpyrrolidone (PVP). Model catalysts have been developed using these nanoparticles by two methods: synthesis of mesoporous silica (SBA-15) in the presence of nanoparticles (nanoparticle encapsulation, NE) to form a composite of metal nanoparticles supported on SBA-15 and by deposition of the particles onto a silicon wafer using Langmuir-Blodgett (LB) monolayer deposition. The particle shapes were analyzed by transmission electron microscopy (TEM) and high resolution TEM (HRTEM) and the sizes were determined by TEM, X-ray diffraction (XRD), and in the case of NE samples, room temperature H₂ and CO adsorption isotherms. Catalytic studies were carried out in homebuilt gas-phase reactors. For the nanoparticles supported on SBA-15, the catalysts are in powder form and were studied using the homebuilt systems as plug-flow reactors. In the case of nanoparticles deposited on silicon wafers, the same systems were operated as batch reactors. This dissertation has focused on the synthesis, characterization, and reaction studies of model noble metal heterogeneous catalysts. Careful control of particle size and shape has been accomplished though solution phase synthesis of Pt and Rh nanoparticles in order to elucidate further structure-reactivity relationships in noble metal catalysis.

Formation of core (polystyrene)-shell (polybenzimidazole) nanoparticles using sulfonated polystyrene as template.

Science.gov (United States)

Hazarika, Mousumi; Arunbabu, Dhamodaran; Jana, Tushar

2010-11-15

We report formation of core (polystyrene)-shell (polybenzimidazole) nanoparticles from a new blend system consisting of an amorphous polymer polybenzimidazole (PBI) and an ionomer sodium salt of sulfonated polystyrene (SPS-Na). The ionomer used for the blending is spherical in shape with sulfonate groups on the surface of the particles. An in depth investigation of the blends at various sulfonation degrees and compositions using Fourier transform infrared (FT-IR) spectroscopy provides direct evidence of specific hydrogen bonding interactions between the N-H groups of PBI and the sulfonate groups of SPS-Na. The disruption of PBI chains self association owing to the interaction between the functional groups of these polymer pairs is the driving force for the blending. Thermodynamical studies carried out by using differential scanning calorimeter (DSC) establish partially miscible phase separated blending of these polymers in a wider composition range. The two distinguishable glass transition temperatures (T(g)) which are different from the neat components and unaltered with the blends composition attribute that the domain size of heterogeneity (d(d)) of the blends is >20 nm since one of the blend component (SPS-Na particle) diameter is ∼70 nm. The diminish of PBI chains self association upon blending with SPS-Na particles and the presence of invariant T(g)'s of the blends suggest the wrapping of PBI chains over the SPS-Na spherical particle surface and hence resulting a core-shell morphology. Transmission electron microscopy (TEM) study provides direct evidence of core-shell nanoparticle formation; where core is the polystyrene and shell is the PBI. The sulfonation degree affects the blends phase separations. The higher degree of sulfonation favors the disruption of PBI self association and thus forms partially miscible two phases blends with core-shell morphology. Copyright © 2010 Elsevier Inc. All rights reserved.

Synthesis, characterization and magnetic properties of highly monodispersed PtNi nanoparticles

International Nuclear Information System (INIS)

Du, Juan-Juan; Yang, Yi; Zhang, Rong-Hua; Zhou, Xin-Wen

2015-01-01

In this paper, we report the controlled-synthesis of PtNi nanoparticles through galvanic displacement reaction and chemical reduction. The size, composition and morphology of the products are characterized by transmission electron microscopy (TEM), powder X-ray diffraction (XRD), energy dispersed X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) analyses. The structure and composition of the PtNi nanoparticles can be controlled by adjusting the synthetic conditions. The possible formation mechanism is obtained from the academic analysis and experimental studies. The results of the magnetic measurement illustrate that the PtNi nanoparticles show a superparamagnetic behavior with a blocking temperature (T B ) about 8.0 K. - Highlights: • Highly monodispersed PtNi nanoparticles were synthesized by galvanic displacement reaction. • The formation of Pt nanocrystals was the foremost step because of its self-catalysis effect. • The PtNi nanoparticles show a superparamagnetic behavior with a T B about 8.0 K

Adsorption of amphipathic dendrons on polystyrene nanoparticles.

Science.gov (United States)

Sakthivel, T; Florence, A T

2003-03-18

Adsorption of dendrons onto nanoparticles may provide new model structures which may be useful in drug and gene delivery. Tritiated amphipathic dendrons having three lipidic (C(14)) chains coupled to branched (dendritic) lysine head groups with 8, 16 or 32 free terminal amino groups have been synthesised by solid phase peptide techniques. The interaction between these tritiated dendrons and 200 nm polystyrene latex nanoparticles was investigated in phosphate buffered saline. The amount of dendron adsorbed increased with increasing concentration of dendrons and then decreased. Maximum adsorption of dendrons per gram of nanoparticles was found to be between 8.2 and 84 x 10(-6)M, the amounts adsorbed being inversely proportional to the number of amino groups present in the molecule. The number of dendron molecules adsorbed per nanoparticle was found to be between 430 and 4421. The degree of adsorption was found to be slightly altered by the temperature. Copyright 2002 Elsevier Science B.V.

Synthesis and characterization of monodispersed silver nanoparticles

Science.gov (United States)

Jegatha Christy, A.; Umadevi, M.

2012-09-01

Synthesis of silver nanoparticles (NPs) has become a fascinating and important field of applied chemical research. In this paper silver NPs were prepared using silver nitrate (AgNO3), gelatin, and cetyl trimethyl ammonium bromide (CTAB). The prepared silver NPs were exposed under the laser ablation. In our photochemical procedure, gelatin acts as a biopolymer and CTAB acts as a reducing agent. The appearance of surface plasmon band around 410 nm indicates the formation of silver NPs. The nature of the prepared silver NPs in the face-centered cubic (fcc) structure are confirmed by the peaks in the x-ray diffraction (XRD) pattern corresponding to (111), (200), (220) and (311) planes. Monodispersed, stable, spherical silver NPs with diameter about 10 nm were obtained and confirmed by high-resolution transmission electron microscope (HRTEM).

Synthesis and characterization of monodispersed silver nanoparticles

International Nuclear Information System (INIS)

Christy, A Jegatha; Umadevi, M

2012-01-01

Synthesis of silver nanoparticles (NPs) has become a fascinating and important field of applied chemical research. In this paper silver NPs were prepared using silver nitrate (AgNO 3 ), gelatin, and cetyl trimethyl ammonium bromide (CTAB). The prepared silver NPs were exposed under the laser ablation. In our photochemical procedure, gelatin acts as a biopolymer and CTAB acts as a reducing agent. The appearance of surface plasmon band around 410 nm indicates the formation of silver NPs. The nature of the prepared silver NPs in the face-centered cubic (fcc) structure are confirmed by the peaks in the x-ray diffraction (XRD) pattern corresponding to (111), (200), (220) and (311) planes. Monodispersed, stable, spherical silver NPs with diameter about 10 nm were obtained and confirmed by high-resolution transmission electron microscope (HRTEM). (paper)

Synthesis of monodispersed silver nanoparticles using Hibiscus cannabinus leaf extract and its antimicrobial activity

Science.gov (United States)

Bindhu, M. R.; Umadevi, M.

2013-01-01

Synthesis of silver nanoparticles using leaf extract of Hibiscus cannabinus has been investigated. The influences of different concentration of H. cannabinus leaf extract, different metal ion concentration and different reaction time on the above cases on the synthesis of nanoparticles were evaluated. The synthesized nanoparticles were characterized using UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM). The prepared silver nanoparticles were monodispersed, spherical in shape with the average particle size of 9 nm and shows surface plasmon peak at 446 nm. The study also reveals that the ascorbic acid present in H. cannabinus leaf extract has been used as reducing agent. The prepared silver nanoparticle shows good antimicrobial activity against Escherichia coli, Proteus mirabilis and Shigella flexneri.

Synthesis and characterization of monodispersed orthorhombic manganese oxide nanoparticles produced by Bacillus sp. cells simultaneous to its bioremediation

Energy Technology Data Exchange (ETDEWEB)

Sinha, Arvind [Enzyme and Microbial Biochemistry Laboratory, Department of Chemistry, Indian Institute of Technology, Delhi, Hauz Khas, New Delhi 110 016 (India); Singh, Vidya Nand; Mehta, Bodh Raj [Thin Film Laboratory, Department of Physics, Indian Institute of Technology, Delhi Hauz Khas, New Delhi 110016 (India); Khare, Sunil Kumar, E-mail: skhare@rocketmail.com [Enzyme and Microbial Biochemistry Laboratory, Department of Chemistry, Indian Institute of Technology, Delhi, Hauz Khas, New Delhi 110 016 (India)

2011-08-30

Highlights: {yields} An efficient process wherein remediated manganese is synthesized into nanoparticles. {yields} A microbial process for manganese nanoparticle synthesis from metal waste streams. {yields} Nanoparticles characterized as monodispersed, spherical and 4.62 {+-} 0.14 nm sized MnO{sub 2}. -- Abstract: A heavy metal resistant strain of Bacillus sp. (MTCC10650) is reported. The strain exhibited the property of bioaccumulating manganese, simultaneous to its remediation. The nanoparticles thus formed were characterized and identified using energy dispersive X-ray analysis (EDAX), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), powder X-ray diffraction (PXRD) and atomic force microscopy (AFM). When the cells were challenged with manganese, the cells effectively synthesized nanoparticles of average size 4.62 {+-} 0.14 nm. These were mostly spherical and monodispersed. The ex situ enzymatically synthesized nanoparticles exhibited an absorbance maximum at 329 nm. These were more discrete, small and uniform, than the manganese oxide nanoparticles recovered after cell sonication. The use of Bacillus sp. cells seems promising and advantageous approach. Since, it serves dual purposes of (i) remediation and (ii) nanoparticle synthesis. Considering the increasing demand of developing environmental friendly and cost effective technologies for nanoparticle synthesis, these cells can be exploited for the remediation of manganese from the environment in conjunction with development of a greener process for the controlled synthesis of manganese oxide nanoparticles.

Synthesis and characterization of monodispersed orthorhombic manganese oxide nanoparticles produced by Bacillus sp. cells simultaneous to its bioremediation

International Nuclear Information System (INIS)

Sinha, Arvind; Singh, Vidya Nand; Mehta, Bodh Raj; Khare, Sunil Kumar

2011-01-01

Highlights: → An efficient process wherein remediated manganese is synthesized into nanoparticles. → A microbial process for manganese nanoparticle synthesis from metal waste streams. → Nanoparticles characterized as monodispersed, spherical and 4.62 ± 0.14 nm sized MnO 2 . -- Abstract: A heavy metal resistant strain of Bacillus sp. (MTCC10650) is reported. The strain exhibited the property of bioaccumulating manganese, simultaneous to its remediation. The nanoparticles thus formed were characterized and identified using energy dispersive X-ray analysis (EDAX), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), powder X-ray diffraction (PXRD) and atomic force microscopy (AFM). When the cells were challenged with manganese, the cells effectively synthesized nanoparticles of average size 4.62 ± 0.14 nm. These were mostly spherical and monodispersed. The ex situ enzymatically synthesized nanoparticles exhibited an absorbance maximum at 329 nm. These were more discrete, small and uniform, than the manganese oxide nanoparticles recovered after cell sonication. The use of Bacillus sp. cells seems promising and advantageous approach. Since, it serves dual purposes of (i) remediation and (ii) nanoparticle synthesis. Considering the increasing demand of developing environmental friendly and cost effective technologies for nanoparticle synthesis, these cells can be exploited for the remediation of manganese from the environment in conjunction with development of a greener process for the controlled synthesis of manganese oxide nanoparticles.

Synthesis of monodispersed silver nanoparticles using Hibiscus cannabinus leaf extract and its antimicrobial activity.

Science.gov (United States)

Bindhu, M R; Umadevi, M

2013-01-15

Synthesis of silver nanoparticles using leaf extract of Hibiscus cannabinus has been investigated. The influences of different concentration of H. cannabinus leaf extract, different metal ion concentration and different reaction time on the above cases on the synthesis of nanoparticles were evaluated. The synthesized nanoparticles were characterized using UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM). The prepared silver nanoparticles were monodispersed, spherical in shape with the average particle size of 9 nm and shows surface plasmon peak at 446 nm. The study also reveals that the ascorbic acid present in H. cannabinus leaf extract has been used as reducing agent. The prepared silver nanoparticle shows good antimicrobial activity against Escherichia coli, Proteus mirabilis and Shigella flexneri. Copyright © 2012 Elsevier B.V. All rights reserved.

Synthesis of Monodispersed Gold Nanoparticles with Exceptional Colloidal Stability with Grafted Polyethylene Glycol-g-polyvinyl Alcohol

Directory of Open Access Journals (Sweden)

Alaaldin M. Alkilany

2015-01-01

Full Text Available Herein, we report the synthesis of spherical gold nanoparticles with tunable core size (23–79 nm in the presence of polyethylene glycol-g-polyvinyl alcohol (PEG-g-PVA grafted copolymer as a reducing, capping, and stabilizing agent in a one-step protocol. The resulted PEG-g-PVA-capped gold nanoparticles are monodispersed with an exceptional colloidal stability against salt addition, repeated centrifugation, and extensive dialysis. The effect of various synthesis parameters and the kinetic/mechanism of the nanoparticle formation are discussed.

Antimicrobial active silver nanoparticles and silver/polystyrene core-shell nanoparticles prepared in room-temperature ionic liquid

International Nuclear Information System (INIS)

An Jing; Wang Desong; Luo Qingzhi; Yuan Xiaoyan

2009-01-01

Uniform silver nanoparticles and silver/polystyrene core-shell nanoparticles were successfully synthesized in a room temperature ionic liquid, 1-n-butyl-3-methylimidazolium tetrafluoroborate ([BMIM].BF 4 ). [BMIM].BF 4 plays a protective role to prevent the nanoparticles from aggregation during the preparation process. Transmission electron micrographs confirm that both silver nanoparticles and core-shell nanoparticles are regular spheres with the sizes in the range of 5-15 nm and 15-25 nm, respectively. The X-ray diffraction analysis reveals the face-centered cubic geometry of silver nanoparticles. The as-prepared nanoparticles were also characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, UV-vis diffuse reflectance spectroscopy and X-ray photoelectron spectroscopy. In addition, antimicrobial activities against E. coli and S. aureus were studied and the results show that both silver nanoparticles and core-shell nanoparticles possess excellent antimicrobial activities. The antimicrobial mechanism of the as-prepared nanoparticles was discussed.

Facile and Scalable Synthesis of Monodispersed Spherical Capsules with a Mesoporous Shell

KAUST Repository

Qi, Genggeng

2010-05-11

Monodispersed HMSs with tunable particle size and shell thickness were successfully synthesized using relatively concentrated polystyrene latex templates and a silica precursor in a weakly basic ethanol/water mixture. The particle size of the capsules can vary from 100 nm to micrometers. These highly engineered monodispersed capsules synthesized by a facile and scalable process may find applications in drug delivery, catalysis, separationm or as biological and chemical microreactors. © 2010 American Chemical Society.

Interaction Between Cyanine Dye IR-783 and Polystyrene Nanoparticles in Solution.

Science.gov (United States)

Zhang, Yunzhi; Xu, Hui; Casabianca, Leah B

2018-05-17

The interactions between small molecule drugs or dyes and nanoparticles are important to the use of nanoparticles in medicine. Noncovalent adsorption of dyes on nanoparticle surfaces is also important to the development of nanoparticle dual-use imaging contrast agents. In the present work, solution-state NMR is used to examine the noncovalent interaction between a near-infrared cyanine dye and the surface of polystyrene nanoparticles in solution. Using 1D proton NMR, we can approximate the number of dye molecules that associate with each nanoparticle for different sized nanoparticles. Saturation-Transfer Difference (STD)-NMR was also used to show that protons near the positively-charged nitrogen in the dye are more strongly associated with the negatively-charged nanoparticle surface than protons near the negatively-charged sulfate groups of the dye. The methods described here can be used to study similar drug or dye molecules interacting with the surface of organic nanoparticles. This article is protected by copyright. All rights reserved.

Synthesis and characterization of titania-based monodisperse fluorescent europium nanoparticles for biolabeling

International Nuclear Information System (INIS)

Tan Mingqian; Wang Guilan; Ye Zhiqiang; Yuan Jingli

2006-01-01

Inorganic-organic hybrid titania-based nanoparticles covalently bound to a fluorescent Eu 3+ chelate of 4,4'-bis(1'',1'',1'',2'',2'',3'',3''-heptafluoro-4'',6''-hexanedion-6''-yl) chlorosulfo-o-terphenyl (BHHCT-Eu 3+ ) were synthesized by a sol-gel technique. A conjugate of BHHCT with 3-[2-(2-aminoethylamino) ethylamino]propyl-trimethoxysilane (APTS) was used as a precursor for the nanoparticle preparation and monodisperse nanoparticles consisting of titania network and silica sub-network covalently bound to the Eu 3+ chelate were prepared by the copolymerization of APTS-BHHCT conjugate, titanium tetraisopropoxide (TTIP) and free APTS in EuCl 3 water-alcohol solution. The effects of reaction conditions on size and fluorescence lifetime of the nanoparticles were investigated. The characterizations by transmission electron microscopy and fluorometric methods indicate that the nanoparticles are near spherical and strongly fluorescent having a fluorescence quantum yield of 11.6% and a long fluorescence lifetime of ∼0.4 ms. The direct-introduced amino groups on the nanoparticle's surface by using free APTS in nanoparticle preparation facilitated the biolabeling process of the nanoparticles. The nanoparticle-labeled streptavidin (SA) was prepared and used in a sandwich-type time-resolved fluoroimmunoassay (TR-FIA) of human prostate-specific antigen (PSA) by using a 96-well microtiter plate as the solid phase carrier. The method gives a detection limit of 66 pg/ml for the PSA assay

Assessment of phototoxicity, skin irritation, and sensitization potential of polystyrene and TiO2 nanoparticles

Science.gov (United States)

Park, Yoon-Hee; Jeong, Sang Hoon; Yi, Sang Min; Hyeok Choi, Byeong; Kim, Yu-Ri; Kim, In-Kyoung; Kim, Meyoung-Kon; Son, Sang Wook

2011-07-01

The human skin equivalent model (HSEM) is well known as an attractive alternative model for evaluation of dermal toxicity. However, only limited data are available on the usefulness of an HSEM for nanotoxicity testing. This study was designed to investigate cutaneous toxicity of polystyrene and TiO2 nanoparticles using cultured keratinocytes, an HSEM, and an animal model. In addition, we also evaluated the skin sensitization potential of nanoparticles using a local lymph node assay with incorporation of BrdU. Findings from the present study indicate that polystyrene and TiO2 nanoparticles do not induce phototoxicity, acute cutaneous irritation, or skin sensitization. Results from evaluation of the HSEMs correspond well with those from animal models. Our findings suggest that the HSEM might be a useful alternative model for evaluation of dermal nanotoxicity.

Assessment of phototoxicity, skin irritation, and sensitization potential of polystyrene and TiO2 nanoparticles

International Nuclear Information System (INIS)

Park, Yoon-Hee; Jeong, Sang Hoon; Yi, Sang Min; Choi, Byeong Hyeok; Son, Sang Wook; Kim, Yu-Ri; Kim, In-Kyoung; Kim, Meyoung-Kon

2011-01-01

The human skin equivalent model (HSEM) is well known as an attractive alternative model for evaluation of dermal toxicity. However, only limited data are available on the usefulness of an HSEM for nanotoxicity testing. This study was designed to investigate cutaneous toxicity of polystyrene and TiO 2 nanoparticles using cultured keratinocytes, an HSEM, and an animal model. In addition, we also evaluated the skin sensitization potential of nanoparticles using a local lymph node assay with incorporation of BrdU. Findings from the present study indicate that polystyrene and TiO 2 nanoparticles do not induce phototoxicity, acute cutaneous irritation, or skin sensitization. Results from evaluation of the HSEMs correspond well with those from animal models. Our findings suggest that the HSEM might be a useful alternative model for evaluation of dermal nanotoxicity.

A constitutive analysis of transient and steady-state elongational viscosities of bidisperse polystyrene blends

DEFF Research Database (Denmark)

Wagner, Manfred H.; Rolon-Garrido, Victor H.; Nielsen, Jens Kromann

2008-01-01

The transient and steady-state elongational viscosity data of three bidisperse polystyrene blends were investigated recently by Nielsen et al. [J. Rheol. 50, 453-476 (2006)]. The blends contain a monodisperse high molar mass component (M-L= 390 kg/ mol) in a matrix of a monodisperse small molar m...

Impact electrochemistry on screen-printed electrodes for the detection of monodispersed silver nanoparticles of sizes 10-107 nm.

Science.gov (United States)

Nasir, Muhammad Zafir Mohamad; Pumera, Martin

2016-10-12

Impact electrochemistry provides a useful alternative technique for the detection of silver nanoparticles in solutions. The combined use of impact electrochemistry on screen-printed electrodes (SPEs) for the successful detection of silver nanoparticles provides an avenue for future on-site, point-of-care detection devices to be made for environmental, medicinal and biological uses. Here we discuss the use of screen-printed electrodes for the detection of well-defined monodispersed silver nanoparticles of sizes 10, 20, 40, 80, and 107 nm.

Characterization of silver/polystyrene nanocomposites prepared by in situ bulk radical polymerization

Energy Technology Data Exchange (ETDEWEB)

Vukoje, Ivana D., E-mail: ivanav@vinca.rs [Vinča Institute of Nuclear Sciences, University of Belgrade, P.O. Box 522, 11001 Belgrade (Serbia); Vodnik, Vesna V., E-mail: vodves@vinca.rs [Vinča Institute of Nuclear Sciences, University of Belgrade, P.O. Box 522, 11001 Belgrade (Serbia); Džunuzović, Jasna V., E-mail: jasnav2002@googlemail.com [Institute of Chemistry, Technology and Metallurgy (ICTM)-Center of Chemistry, University of Belgrade, Studentski trg 12-16, 11000 Belgrade (Serbia); Džunuzović, Enis S., E-mail: edzunuzovic@tmf.bg.ac.rs [Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11120 Belgrade (Serbia); Marinović-Cincović, Milena T., E-mail: milena@vinca.rs [Vinča Institute of Nuclear Sciences, University of Belgrade, P.O. Box 522, 11001 Belgrade (Serbia); Jeremić, Katarina, E-mail: kjeremic@tmf.bg.ac.rs [Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11120 Belgrade (Serbia); Nedeljković, Jovan M., E-mail: jovned@vinca.rs [Vinča Institute of Nuclear Sciences, University of Belgrade, P.O. Box 522, 11001 Belgrade (Serbia)

2014-01-01

Graphical abstract: - Highlights: • Synthesis and characterization of polystyrene nanocomposites based on Ag nanoparticles. • The glass transition temperature decreased in nanocomposites with respect to the pure polymer. • Resistance of the polymer to thermal degradation enhanced with Ag nanoparticles content. - Abstract: Nanocomposites (NCs) with different content of silver nanoparticles (Ag NPs) embeded in polystyrene (PS) matrix were prepared by in situ bulk radical polymerization. The nearly monodisperse Ag NPs protected with oleylamine were synthesized via organic solvo-thermal method and further used as a filler. The as-prepared spherical Ag NPs with diameter of 7.0 ± 1.5 nm were well dispersed in the PS matrix. The structural properties of the resulting Ag/PS NCs were characterized by transmission electron microscope (TEM) and Fourier transform infrared (FTIR) spectroscopy, while optical properties were characterized using optical absorption measurements. The gel permeation chromatography (GPC) measurements showed that the presence of Ag NPs stabilized with oleylamine has no influence on the molecular weight and polydispersity of the PS matrix. The influence of silver content on the thermal properties of Ag/PS NCs was investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results indicated that resistance of PS to thermal degradation was improved upon incorporation of Ag NPs. The Ag/PS NCs have lower glass transition temperatures than neat PS because loosely packed oleylamine molecules at the interface caused the increase of free volume and chain segments mobility near the surface of Ag NPs.

Biocompatibility, endocytosis, and intracellular trafficking of mesoporous silica and polystyrene nanoparticles in ovarian cancer cells: effects of size and surface charge groups

Science.gov (United States)

Ekkapongpisit, Maneerat; Giovia, Antonino; Follo, Carlo; Caputo, Giuseppe; Isidoro, Ciro

2012-01-01

Background and methods Nanoparticles engineered to carry both a chemotherapeutic drug and a sensitive imaging probe are valid tools for early detection of cancer cells and to monitor the cytotoxic effects of anticancer treatment simultaneously. Here we report on the effect of size (10–30 nm versus 50 nm), type of material (mesoporous silica versus polystyrene), and surface charge functionalization (none, amine groups, or carboxyl groups) on biocompatibility, uptake, compartmentalization, and intracellular retention of fluorescently labeled nanoparticles in cultured human ovarian cancer cells. We also investigated the involvement of caveolae in the mechanism of uptake of nanoparticles. Results We found that mesoporous silica nanoparticles entered via caveolae-mediated endocytosis and reached the lysosomes; however, while the 50 nm nanoparticles permanently resided within these organelles, the 10 nm nanoparticles soon relocated in the cytoplasm. Naked 10 nm mesoporous silica nanoparticles showed the highest and 50 nm carboxyl-modified mesoporous silica nanoparticles the lowest uptake rates, respectively. Polystyrene nanoparticle uptake also occurred via a caveolae-independent pathway, and was negatively affected by serum. The 30 nm carboxyl-modified polystyrene nanoparticles did not localize in lysosomes and were not toxic, while the 50 nm amine-modified polystyrene nanoparticles accumulated within lysosomes and eventually caused cell death. Ovarian cancer cells expressing caveolin-1 were more likely to endocytose these nanoparticles. Conclusion These data highlight the importance of considering both the physicochemical characteristics (ie, material, size and surface charge on chemical groups) of nanoparticles and the biochemical composition of the cell membrane when choosing the most suitable nanotheranostics for targeting cancer cells. PMID:22904626

A comparison of atomic force microscopy (AFM) and dynamic light scattering (DLS) methods to characterize nanoparticle size distributions

International Nuclear Information System (INIS)

Hoo, Christopher M.; Starostin, Natasha; West, Paul; Mecartney, Martha L.

2008-01-01

This paper compares the accuracy of conventional dynamic light scattering (DLS) and atomic force microscopy (AFM) for characterizing size distributions of polystyrene nanoparticles in the size range of 20-100 nm. Average DLS values for monosize dispersed particles are slightly higher than the nominal values whereas AFM values were slightly lower than nominal values. Bimodal distributions were easily identified with AFM, but DLS results were skewed toward larger particles. AFM characterization of nanoparticles using automated analysis software provides an accurate and rapid analysis for nanoparticle characterization and has advantages over DLS for non-monodispersed solutions.

Steady shear rheology of dilute polystyrene particle gels

NARCIS (Netherlands)

Folkersma, R.; Diemen, van A.J.G.; Laven, J.; Stein, H.N.

1999-01-01

This paper describes an experimental study on dispersions of monodisperse polystyrene (PS) spheres with a typical radius of 1 µm, dispersed in an electrolyte at high ionic strength, screening the electrostatic repulsion. These suspensions gelate at rest even at low volume fractions of PS particles.

A new method for preparing mono-dispersed nanoparticles using magnetized water

Science.gov (United States)

Nakhaei Pour, Ali; Gholizadeh, Mostafa; Housaindokht, Mohammadreza; Moosavi, Fatemeh; Monhemi, Hasan

2017-04-01

We studied the use of magnetized water on the size of the nanoparticles. Magnetized water found to reduce the diameter of the nanoparticles during a homogeneous precipitation process, which is a combination of nucleation and nuclei growth processes. We found that the modified water, which demonstrated different physical properties especially on the surface tension and viscosity, significantly influenced the both processes. Therefore, the nucleation process was initially prolonged in the homogeneous precipitation process due to the lower critical size of nucleus and higher rate of nucleation, and consequently formed smaller particles and a larger number of particles. Furthermore, the growth rate of nanoparticles was hindered owing to the higher viscosity of the water and restriction in the mass transport process. As a result, the precipitated particles with the magnetized water were eventually structured smaller particle diameter compared to the bulk. The presented method in here indicated a low cost, straightforward, and feasible technique for industrial application. In addition, this method could open a new promising perspective on nanomaterial synthesis in order to facilitate the production of monodispersed nanoparticles. Molecular dynamic confirmed that surface tension decreased as the external magnetic field was applied. Moreover, the density profile illustrated that the average number of hydrogen atoms is greater than oxygen atoms.

Assessment of phototoxicity, skin irritation, and sensitization potential of polystyrene and TiO{sub 2} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Park, Yoon-Hee; Jeong, Sang Hoon; Yi, Sang Min; Choi, Byeong Hyeok; Son, Sang Wook [Laboratory of Cell Signaling and Nanomedicine, Department of Dermatology and Division of Brain Korea 21 Project for Biomedical Science, Korea University College of Medicine, Seoul (Korea, Republic of); Kim, Yu-Ri; Kim, In-Kyoung; Kim, Meyoung-Kon [Department of Biochemistry and Molecular Biology, Korea University College of Medicine, Seoul (Korea, Republic of)

2011-07-06

The human skin equivalent model (HSEM) is well known as an attractive alternative model for evaluation of dermal toxicity. However, only limited data are available on the usefulness of an HSEM for nanotoxicity testing. This study was designed to investigate cutaneous toxicity of polystyrene and TiO{sub 2} nanoparticles using cultured keratinocytes, an HSEM, and an animal model. In addition, we also evaluated the skin sensitization potential of nanoparticles using a local lymph node assay with incorporation of BrdU. Findings from the present study indicate that polystyrene and TiO{sub 2} nanoparticles do not induce phototoxicity, acute cutaneous irritation, or skin sensitization. Results from evaluation of the HSEMs correspond well with those from animal models. Our findings suggest that the HSEM might be a useful alternative model for evaluation of dermal nanotoxicity.

Temperature dependence of exchange anisotropy in monodisperse cobalt nanoparticles with a cobalt oxide shell

International Nuclear Information System (INIS)

Spasova, M.; Wiedwald, U.; Farle, M.; Radetic, T.; Dahmen, U.; Hilgendorff, M.; Giersig, M.

2004-01-01

Exchange anisotropy was studied by SQUID magnetometry on an array of monodisperse colloidal nanoparticles consisting of a 7-8 nm diameter FCC Co core covered with a 2-2.5 nm thick FCC CoO shell. Temperature-dependent measurements of the exchange bias field show that the exchange anisotropy vanishes when a magnetic field was applied during cooling below 150 K. The suppression of exchange anisotropy is due to uncompensated interfacial antiferromagnetic spins

Morphology and Viscoelastic Properties of Polystyrene Blended with Fully Condensed Polyhedral Oligomeric Silsesquioxanes

National Research Council Canada - National Science Library

Namani, Madhu; Geng, Hai-Ping; Lee, Andre; Blanski, Rusty L

2004-01-01

.... Experiments were performed using a nearly-monodisperse molecular weight polystyrene (PS) blended with varying amounts of two fully condensed POSS molecules surrounded with phenethyl and styrenyl groups...

The Synthesis, Characterization and Catalytic Reaction Studies of Monodisperse Platinum Nanoparticles in Mesoporous Oxide Materials

Energy Technology Data Exchange (ETDEWEB)

Rioux, Robert M. [Univ. of California, Berkeley, CA (United States)

2006-01-01

A catalyst design program was implemented in which Pt nanoparticles, either of monodisperse size and/or shape were synthesized, characterized and studied in a number of hydrocarbon conversion reactions. The novel preparation of these materials enables exquisite control over their physical and chemical properties that could be controlled (and therefore rationally tuned) during synthesis. The ability to synthesize rather than prepare catalysts followed by thorough characterization enable accurate structure-function relationships to be elucidated. This thesis emphasizes all three aspects of catalyst design: synthesis, characterization and reactivity studies. The precise control of metal nanoparticle size, surface structure and composition may enable the development of highly active and selective heterogeneous catalysts.

Rational design of Raman-labeled nanoparticles for a dual-modality, light scattering immunoassay on a polystyrene substrate.

Science.gov (United States)

Israelsen, Nathan D; Wooley, Donald; Hanson, Cynthia; Vargis, Elizabeth

2016-01-01

Surface-enhanced Raman scattering (SERS) is a powerful light scattering technique that can be used for sensitive immunoassay development and cell labeling. A major obstacle to using SERS is the complexity of fabricating SERS probes since they require nanoscale characterization and optical uniformity. The light scattering response of SERS probes may also be modulated by the substrate used for SERS analysis. A typical SERS substrate such as quartz can be expensive. Polystyrene is a cheaper substrate option but can decrease the SERS response due to interfering Raman emission peaks and high background fluorescence. The goal of this research is to develop an optimized process for fabricating Raman-labeled nanoparticles for a SERS-based immunoassay on a polystyrene substrate. We have developed a method for fabricating SERS nanoparticle probes for use in a light scattering immunoassay on a polystyrene substrate. The light scattering profile of both spherical gold nanoparticle and gold nanorod SERS probes were characterized using Raman spectroscopy and optical absorbance spectroscopy. The effects of substrate interference and autofluorescence were reduced by selecting a Raman reporter with a strong light scattering response in a spectral region where interfering substrate emission peaks are minimized. Both spherical gold nanoparticles and gold nanorods SERS probes used in the immunoassay were detected at labeling concentrations in the low pM range. This analytical sensitivity falls within the typical dynamic range for direct labeling of cell-surface biomarkers using SERS probes. SERS nanoparticle probes were fabricated to produce a strong light scattering signal despite substrate interference. The optical extinction and inelastic light scattering of these probes was detected by optical absorbance spectroscopy and Raman spectroscopy, respectively. This immunoassay demonstrates the feasibility of analyzing strongly enhanced Raman signals on polystyrene, which is an

Monodisperse gold-palladium alloy nanoparticles and their composition-controlled catalysis in formic acid dehydrogenation under mild conditions.

Science.gov (United States)

Metin, Önder; Sun, Xiaolian; Sun, Shouheng

2013-02-07

Monodisperse 4 nm AuPd alloy nanoparticles with controlled composition were synthesized by co-reduction of hydrogen tetrachloroaurate(III) hydrate and palladium(II) acetylacetonate with a borane-morpholine complex in oleylamine. These NPs showed high activity (TOF = 230 h(-1)) and stability in catalyzing formic acid dehydrogenation and hydrogen production in water at 50 °C without any additives.

Repetitive heterocoagulation of oppositely charged particles for enhancement of magnetic nanoparticle loading into monodisperse silica particles.

Science.gov (United States)

Matsumoto, Hideki; Nagao, Daisuke; Konno, Mikio

2010-03-16

Oppositely charged particles were repetitively heterocoagulated to fabricate highly monodisperse magnetic silica particles with high loading of magnetic nanoparticles. Positively charged magnetic nanoparticles prepared by surface modification with N-trimethoxysilylpropyl-N,N,N-trimethylammonium chloride (TSA) were used to heterocoagulate with silica particles under basic conditions to give rise to negative silica surface charge and prevent the oxidation of the magnetic nanoparticles. The resultant particles of silica core homogeneously coated with the magnetic nanoparticles were further coated with thin silica layer with sodium silicate in order to enhance colloidal stability and avoid desorption of the magnetic nanoparticles from the silica cores. Five repetitions of the heterocoagulation and the silica coating could increase saturation magnetization of the magnetic silica particles to 27.7 emu/g, keeping the coefficient of variation of particle sizes (C(V)) less than 6.5%. Highly homogeneous loading of the magnetic component was confirmed by measuring Fe-to-Si atomic ratios of individual particles with energy dispersive X-ray spectroscopy.

Biocompatibility, endocytosis, and intracellular trafficking of mesoporous silica and polystyrene nanoparticles in ovarian cancer cells: effects of size and surface charge groups

Directory of Open Access Journals (Sweden)

Ekkapongpisit M

2012-07-01

Full Text Available Maneerat Ekkapongpisit,1 Antonino Giovia,1 Carlo Follo,1 Giuseppe Caputo,2,3 Ciro Isidoro11Laboratory of Molecular Pathology and Nanobioimaging, Department of Health Sciences, Università del Piemonte Orientale “A Avogadro”, Novara, 2Dipartimento di Chimica dell’Università di Torino, Torino, 3Cyanine Technology SpA, Torino, ItalyBackground and methods: Nanoparticles engineered to carry both a chemotherapeutic drug and a sensitive imaging probe are valid tools for early detection of cancer cells and to monitor the cytotoxic effects of anticancer treatment simultaneously. Here we report on the effect of size (10–30 nm versus 50 nm, type of material (mesoporous silica versus polystyrene, and surface charge functionalization (none, amine groups, or carboxyl groups on biocompatibility, uptake, compartmentalization, and intracellular retention of fluorescently labeled nanoparticles in cultured human ovarian cancer cells. We also investigated the involvement of caveolae in the mechanism of uptake of nanoparticles.Results: We found that mesoporous silica nanoparticles entered via caveolae-mediated endocytosis and reached the lysosomes; however, while the 50 nm nanoparticles permanently resided within these organelles, the 10 nm nanoparticles soon relocated in the cytoplasm. Naked 10 nm mesoporous silica nanoparticles showed the highest and 50 nm carboxyl-modified mesoporous silica nanoparticles the lowest uptake rates, respectively. Polystyrene nanoparticle uptake also occurred via a caveolae-independent pathway, and was negatively affected by serum. The 30 nm carboxyl-modified polystyrene nanoparticles did not localize in lysosomes and were not toxic, while the 50 nm amine-modified polystyrene nanoparticles accumulated within lysosomes and eventually caused cell death. Ovarian cancer cells expressing caveolin-1 were more likely to endocytose these nanoparticles.Conclusion: These data highlight the importance of considering both the

A novel method for the synthesis of monodisperse gold-coated silica nanoparticles

International Nuclear Information System (INIS)

English, Michael D.; Waclawik, Eric R.

2012-01-01

Monodisperse silica nanoparticles were synthesised by the well-known Stober protocol, then dispersed in acetonitrile (ACN) and subsequently added to a bisacetonitrile gold(I) coordination complex ([Au(MeCN) 2 ] + ) in ACN. The silica hydroxyl groups were deprotonated in the presence of ACN, generating a formal negative charge on the siloxy groups. This allowed the [Au(MeCN) 2 ] + complex to undergo ligand exchange with the silica nanoparticles and form a surface coordination complex with reduction to metallic gold (Au 0 ) proceeding by an inner sphere mechanism. The residual [Au(MeCN) 2 ] + complex was allowed to react with water, disproportionating into Au 0 and Au(III), respectively, with the Au 0 adding to the reduced gold already bound on the silica surface. The so-formed metallic gold seed surface was found to be suitable for the conventional reduction of Au(III) to Au 0 by ascorbic acid (ASC). This process generated a thin and uniform gold coating on the silica nanoparticles. The silica NPs batches synthesised were in a size range from 45 to 460 nm. Of these silica NP batches, the size range from 400 to 480 nm were used for the gold-coating experiments.

Preparation of size-tunable, highly monodisperse PVP-protected Pt-nanoparticles by seed-mediated growth

International Nuclear Information System (INIS)

Koebel, Matthias M.; Jones, Louis C.; Somorjai, Gabor A.

2008-01-01

We demonstrate a preparative method which produces highly monodisperse Pt-nanoparticles of tunable size without the external addition of seed particles. Hexachloroplatinic acid is dosed slowly to an ethylene glycol solution at 120 o C and reduced in the presence of a stabilizing polymer poly-N-vinylpyrrolidone (PVP). Slow addition of the Pt-salt will first lead to the formation of nuclei (seeds) which then grow further to produce larger particles of any desired size between 3 and 8 nm. The amount of added hexachloroplatinic acid precursor controls the size of the final nanoparticle product. TEM was used to determine size and morphology and to confirm the crystalline nature of the nanoparticles. Good reproducibility of the technique was demonstrated. Above 7 nm, the particle shape and morphology changes suddenly indicating a change in the deposition selectivity of the Pt-precursor from (100) towards (111) crystal faces and breaking up of larger particles into smaller entities.

Magnetic properties of Fe-oxide and (Fe, Co) oxide nanoparticles synthesized in polystyrene resin matrix

Science.gov (United States)

Rodak, D.; Kroll, E.; Tsoi, G. M.; Vaishnava, P. P.; Naik, R.; Wenger, L. E.; Suryanarayanan, R.; Naik, V. M.; Boolchand, P.

2003-03-01

Magnetic nanoparticles have potential applications ranging from drug delivery and imaging in the medical field to sensing and memory storage in technology. The preparation, structure, and physical properties of iron oxide-based nanoparticles synthesized by ion exchange in a polystyrene resin matrix have been investigated. Employing a synthesis method developed originally by Ziolo, et. al^1, nanoparticles were prepared in a sulfonated divinyl benzene polystyrene resin matrix using various aqueous solutions of (1) FeCl_2, (2) FeCl_3, (3) FeCl2 : 2FeCl3 , (4) 9FeCl2 : CoCl_2, and (5) 4FeCl2 : CoCl_2. Powder x-ray diffraction measurements were used to identify the phases present while transmission electron microscopy was used for particle size distribution determinations. SQUID magnetization measurements (field-cooled and zero-field-cooled) and Fe^57 Mössbauer effect measurements indicate the presence of ferromagnetic iron oxide phases and a superparamagnetic behavior with blocking temperatures (T_B) varying from 50 K to room temperature. Nanoparticles synthesized using a stoichiometric mixture of FeCl2 and FeCl3 exhibit the lowest TB and smallest particle size distribution. The Mössbauer effect measurements have also been used to identify the iron oxides phases present and their relative amounts in the nanoparticles ^1R.F. Ziolo, et al., Science 207, 219 (1992). *Permanent address: Kettering University, Flint, MI 48504

Mixed matrix membranes prepared from high impact polystyrene with dispersed TiO2 nanoparticles for gas separation

Directory of Open Access Journals (Sweden)

P. Safaei

2016-01-01

Full Text Available The current study presents synthesis and characterization of high impact polystyrene - TiO2 nanoparticles mixed matrix membranes for separation of carbon dioxide from nitrogen. The solution-casting method was used for preparation of membranes. The nano mixed matrix membranes were characterized using scanning electron microscopy to ensure the suitable dispersion of nano particles in high impact polystyrene matrix. The effect of TiO2 nanoparticles loading on membrane performance was investigated. The separation performance of synthesized membranes was investigated in separation of CO2 from CO2/N2 mixture. Effect of feed pressure and TiO2 content on separation of CO2 was studied. The results revealed that increase of feed pressure decreases flux of gases through the mixed matrix membrane. The results also confirmed that the best separation performance can be obtained at TiO2 nanoparticles loading of 7 wt.%.

Uniaxial Elongational viscosity of bidisperse polystyrene melts

DEFF Research Database (Denmark)

Nielsen, Jens Kromann; Rasmussen, Henrik K.; Hassager, Ole

2006-01-01

The startup and steady uniaxial elongational viscosity have been measured for three bidisperse polystyrene (PS) melts, consisting of blends of monodisperse PS with molecular weights of 52 kg/mole or 103 kg/mole and 390 kg/mole. The bidisperse melts have a maximum in the steady elongational...... viscosity, of up to a factor of 7 times the Trouton limit of 3 times the zero-shear viscosity....

Fabrication and characterisation of ligand-functionalised ultrapure monodispersed metal nanoparticle nanoassemblies employing advanced gas deposition technique

Science.gov (United States)

Geremariam Welearegay, Tesfalem; Cindemir, Umut; Österlund, Lars; Ionescu, Radu

2018-02-01

Here, we report for the first time the fabrication of ligand-functionalised ultrapure monodispersed metal nanoparticles (Au, Cu, and Pt) from their pure metal precursors using the advanced gas deposition technique. The experimental conditions during nanoparticle formation were adjusted in order to obtain ultrafine isolated nanoparticles on different substrates. The morphology and surface analysis of the as-deposited metal nanoparticles were investigated using scanning electron microscopy, x-ray diffraction and Fourier transform infra-red spectroscopy, which demonstrated the formation of highly ordered pure crystalline nanoparticles with a relatively uniform size distribution of ∼10 nm (Au), ∼4 nm (Cu) and ∼3 nm (Pt), respectively. A broad range of organic ligands containing thiol or amine functional groups were attached to the nanoparticles to form continuous networks of nanoparticle-ligand nanoassemblies, which were characterised by scanning electron microscopy and x-ray photoelectron spectroscopy. The electrical resistance of the functional nanoassemblies deposited in the gap spacing of two microfabricated parallel Au electrodes patterned on silicon substrates ranged between tens of kΩ and tens of MΩ, which is suitable for use in many applications including (bio)chemical sensors, surface-enhanced Raman spectroscopy and molecular electronic rectifiers.

Investigation of Monodisperse Dendrimeric Polysaccharide Nanoparticle Dispersions Using Small Angle Neutron Scattering

Science.gov (United States)

Atkinson, John; Nickels, Jonathan; Papp-Szabo, Erzsi; Katsaras, John; Dutcher, John

2015-03-01

Phytoglycogen is a highly branched polysaccharide that is very similar to the energy storage molecule glycogen. We have isolated monodisperse phytoglycogen nanoparticles from corn and these particles are attractive for applications in the cosmetic, food and beverage, and biomedical industries. Many of these promising applications are due to the special interaction between the nanoparticles and water, which results in: (1) high solubility; (2) low viscosity and high stability in aqueous dispersions; and (3) a remarkable capacity to sequester and retain water. Our rheology measurements indicate that the nanoparticles behave like hard spheres in water, with the viscosity diverging for concentrations >25% (w/w). Because of this, aqueous suspensions of phytoglycogen provide an ideal platform for detailed testing of theories of colloidal glasses and jamming. To further explore the interaction of the phytoglycogen particles and water, we have performed small angle neutron scattering (SANS) measurements on the Extended Q-Range SANS (EQ-SANS) diffractometer at the Spallation Neutron Source at Oak Ridge National Laboratory. Measurements performed on phytoglycogen dispersions in mixtures of hydrogenated and deuterated water have allowed us to determine the particle size and average particle spacing as a function of the phytoglycogen concentration in the limits of dilute and concentrated dispersions.

Thermal dewetting behavior of polystyrene composite thin films with organic-modified inorganic nanoparticles.

Science.gov (United States)

Kubo, Masaki; Takahashi, Yosuke; Fujii, Takeshi; Liu, Yang; Sugioka, Ken-ichi; Tsukada, Takao; Minami, Kimitaka; Adschiri, Tadafumi

2014-07-29

The thermal dewetting of polystyrene composite thin films with oleic acid-modified CeO2 nanoparticles prepared by the supercritical hydrothermal synthesis method was investigated, varying the nanoparticle concentration (0-30 wt %), film thickness (approximately 50 and 100 nm), and surface energy of silanized silicon substrates on which the composite films were coated. The dewetting behavior of the composite thin films during thermal annealing was observed by an optical microscope. The presence of nanoparticles in the films affected the morphology of dewetting holes, and moreover suppressed the dewetting itself when the concentration was relatively high. It was revealed that there was a critical value of the surface energy of the substrate at which the dewetting occurred. In addition, the spatial distributions of nanoparticles in the composite thin films before thermal annealing were investigated using AFM and TEM. As a result, we found that most of nanoparticles segregated to the surface of the film, and that such distributions of nanoparticles contribute to the stabilization of the films, by calculating the interfacial potential of the films with nanoparticles.

Design and development of anisotropic inorganic/polystyrene nanocomposites by surface modification of zinc oxide nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Han, Xiao [School of Materials Science and Engineering, Tongji University, Shanghai 200092 (China); Research Center for Translational Medicine, East Hospital, the Institute for Biomedical Engineering & Nano Science, Tongji University School of Medicine, Shanghai 200092 (China); Huang, Shiming [Department of Physics, Tongji University, Shanghai 200092 (China); Wang, Yilong, E-mail: yilongwang@tongji.edu.cn [Research Center for Translational Medicine, East Hospital, the Institute for Biomedical Engineering & Nano Science, Tongji University School of Medicine, Shanghai 200092 (China); Shi, Donglu, E-mail: shid@ucmail.uc.edu [Research Center for Translational Medicine, East Hospital, the Institute for Biomedical Engineering & Nano Science, Tongji University School of Medicine, Shanghai 200092 (China); The Materials Science and Engineering Program, College of Engineering and Applied Science, University of Cincinnati, Cincinnati, OH 45221 (United States)

2016-07-01

Anisotropic yolk/shell or Janus inorganic/polystyrene nanocomposites were prepared by combining miniemulsion polymerization and sol–gel reaction. The morphologies of the anisotropic composites were found to be greatly influenced by surface modification of zinc oxide (ZnO) nanoparticle seeds. Two different types of the oleic acid modified ZnO nanoparticles (OA-ZnO) were prepared by post-treatment of commercial ZnO powder and homemade OA-ZnO nanoparticles. The morphologies and properties of the nanocomposites were investigated by transmission electron microscope (TEM), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), dynamic light scattering (DLS), and energy dispersive X-ray spectroscopy (EDX). It was found that both post-treated OA-ZnO and in-situ prepared OA-ZnO nanoparticles resulted in the yolk–shell and Janus structure nanocomposites, but with varied size and morphology. These nanocomposites showed stable and strong fluorescence by introducing quantum dots as the co-seeds. The fluorescent anisotropic nanocomposites were decorated separately with surface carboxyl and hydroxyl groups. These composites with unique anisotropic properties will have high potential in biomedical applications, particularly in bio-detection. - Graphical abstract: Design and development of anisotropic inorganic/polystyrene nanocomposites by surface modification of zinc oxide nanoparticles. - Highlights: • Non-magnetic anisotropic yolk/shell or Janus nanocomposites are prepared and characterized. • Different surface modification of zinc oxide (ZnO) nanoparticles results in varied morphology and size of the final product. • Fluorescent anisotropic nanocomposites embodying quantum dots are an ideal candidate for bio-detection applications.

Photophysical study of blue-light excitable ternary Eu(III) complexes and their encapsulation into polystyrene nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Räsänen, Markus, E-mail: mpvras@utu.fi [Department of Chemistry, University of Turku, FIN-20014 Turku (Finland); Takalo, Harri [DHR Finland Oy, Innotrac Diagnostics, Biolinja 12, FIN-20750 Turku (Finland); Soukka, Tero [Department of Biochemistry/Biotechnology, University of Turku, FIN-20014 Turku (Finland); Haapakka, Keijo; Kankare, Jouko [Department of Chemistry, University of Turku, FIN-20014 Turku (Finland)

2015-04-15

In this work, 14 ternary Eu(III) complexes were studied by means of spectroscopy. The studied Eu(III) complexes consisted of Lewis bases (4′-(4-diethylaminophenyl)-2,2′:6′,2″-terpyridine (L{sup 8}) or 1,10-phenanthroline (L{sup 9})) and differently substituted β-diketones. The ternary complexes with L{sup 8} show the excitation peak at 405 nm and the quantum yield even 76%. The brightest ternary complex at the 405 nm excitation was Eu(L{sup 3}){sub 3}L{sup 8} while Eu(L{sup 7}){sub 3}L{sup 8} (HL{sup 3}=4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione, HL{sup 7}=1-(9-ethyl-9H-carbazol-3-yl)-4,4,5,5,5-pentafluoro-1,3-pentanedione) was found to be the brightest at the ligand-centred excitation maximum. The ternary complexes were studied mainly in toluene as the model environment for the polystyrene nanoparticle cavities. The complexes were successfully loaded into the polystyrene nanoparticles enabling their bioanalytical application in aqueous environment. The encapsulation of the complexes preserved, or even enhanced, their good photophysical features. - Highlights: • Ternary Eu{sup 3+} complexes with some β-diketone and substituted terpyridine were studied. • Ternary complexes with substituted terpyridine showed blue-light excitability. • Ternary complexes were successfully loaded into the polystyrene nanoparticles. • Encapsulation of the complexes preserved their good photophysical features.

Undecylprodigiosin conjugated monodisperse gold nanoparticles efficiently cause apoptosis in colon cancer cells in vitro

Energy Technology Data Exchange (ETDEWEB)

Nikodinovic-Runic, Jasmina; Mojic, Marija; Kang, Yijin; Maksimovic-Ivanic, Danijela; Mijatovic, Sanja; Vasiljevic, Branka; Stamenkovic, Vojislav R.; Senerovic, Lidija

2014-01-01

Bacterial pigment undecylprodigiosin (UP) was produced using Streptomyces sp. JS520 and conjugated to monodisperse gold nanoparticles (UP-Au). Both UP and UP-Au showed cytocidal activity towards melanoma (A375), lung carcinoma (A549), breast cancer (MCF-7) and colon cancer (HCT-116) cells, inducing apoptosis with IC50 values ranging from 0.4 to 4 mu g ml(-1). Unconjugated UP had a tendency to lose its activity over time and to change biophysical characteristics over pH. The loss of the pigment potency was overcome by conjugation with gold nanoparticles. UP-Au exhibited high stability over pH 3.8 to 7.4 and its activity remained unaffected in time. Nano-packing changed the mechanism of UP toxicity by converting the intracellular signals from a mitochondrial dependent to a mitochondrial independent apoptotic process. The availability of nonpyrogenic UP in high amounts, together with specific anticancer activity and improved stability in the complex with gold nanoparticles, presents a novel platform for further development of UP-Au complexes as an anticancer drug suitable for clinical applications.

Preparation of magnetic nanoparticles embedded in polystyrene microspheres

International Nuclear Information System (INIS)

Nguyen Hoang Hai; Nguyen Hoang Luong; Nguyen Chau; Ngo Quy Tai

2009-01-01

Superparamagnetic particles are widely used for biological applications such as cell separation. The size of the particles is normally in the range of 10 - 20 nm which is much smaller than the size of a cell. Therefore small particles create small force which is not strong enough to separate the cells from solution. Superparamagnetic nanoparticles embedded in Polystyrene microspheres (magnetic beads) are very useful for cell separation. Magnetic beads have been prepared by solvent evaporation of an emulsion. The beads with size of 0.2 μm - 1.0 μm have a saturation magnetization of 10 - 25 emu/g. The change of the amount of surfactants, volatile solvent, magnetic particles resulted to the change of size, magnetic properties of the magnetic beads.

Final Report for Fractionation and Separation of Polydisperse Nanoparticles into Distinct Monodisperse Fractions Using CO2 Expanded Liquids

Energy Technology Data Exchange (ETDEWEB)

Chistopher Roberts

2007-08-31

The overall objective of this project was to facilitate efficient fractionation and separation of polydisperse metal nanoparticle populations into distinct monodisperse fractions using the tunable solvent properties of gas expanded liquids. Specifically, the dispersibility of ligand-stabilized nanoparticles in an organic solution was controlled by altering the ligand-solvent interaction (solvation) by the addition of carbon dioxide (CO{sub 2}) gas as an antisolvent (thereby tailoring the bulk solvent strength) in a custom high pressure apparatus developed in our lab. This was accomplished by adjusting the CO{sub 2} pressure over the liquid dispersion, resulting in a simple means of tuning the nanoparticle precipitation by size. Overall, this work utilized the highly tunable solvent properties of organic/CO{sub 2} solvent mixtures to selectively size-separate dispersions of polydisperse nanoparticles (ranging from 1 to 20 nm in size) into monodisperse fractions ({+-}1nm). Specifically, three primary tasks were performed to meet the overall objective. Task 1 involved the investigation of the effects of various operating parameters (such as temperature, pressure, ligand length and ligand type) on the efficiency of separation and fractionation of Ag nanoparticles. In addition, a thermodynamic interaction energy model was developed to predict the dispersibility of different sized nanoparticles in the gas expanded liquids at various conditions. Task 2 involved the extension of the experimental procedures identified in task 1 to the separation of other metal particles used in catalysis such as Au as well as other materials such as semiconductor particles (e.g. CdSe). Task 3 involved using the optimal conditions identified in tasks 1 and 2 to scale up the process to handle sample sizes of greater than 1 g. An experimental system was designed to allow nanoparticles of increasingly smaller sizes to be precipitated sequentially in a vertical series of high pressure vessels by

Monodisperse microbeads of hypercrosslinked polystyrene for liquid and supercritical fluid chromatography

Science.gov (United States)

Tsyurupa, M. P.; Blinnikova, Z. K.; Il'in, M. M.; Davankov, V. A.; Parenago, O. O.; Pokrovskii, O. I.; Usovich, O. I.

2015-11-01

Monodisperse styrene-divinylbenzene (1 wt %) copolymer microbeads are obtained via the elaborate method of high-productivity precipitation polymerization. The crosslinking of this copolymer with chloromethyl methyl ether in the presence of Friedel-Crafts catalyst yields porous hypercrosslinked polymers with degrees of crosslinking that range from 200 to 500%. Microbead sorbents are shown to be suited for selective stationary phases for high-performance liquid chromatography and supercritical fluid chromatography.

In situ grazing incidence small-angle X-ray scattering investigation of polystyrene nanoparticle spray deposition onto silicon.

Science.gov (United States)

Herzog, Gerd; Benecke, Gunthard; Buffet, Adeline; Heidmann, Berit; Perlich, Jan; Risch, Johannes F H; Santoro, Gonzalo; Schwartzkopf, Matthias; Yu, Shun; Wurth, Wilfried; Roth, Stephan V

2013-09-10

We investigated the spray deposition and subsequent self-assembly during drying of a polystyrene nanoparticle dispersion with in situ grazing incidence small-angle X-ray scattering at high time resolution. During the fast deposition of the dispersion and the subsequent evaporation of the solvent, different transient stages of nanoparticle assembly can be identified. In the first stage, the solvent starts to evaporate without ordering of the nanoparticles. During the second stage, large-scale structures imposed by the breakup of the liquid film are observable. In this stage, the solvent evaporates further and nanoparticle ordering starts. In the late third drying stage, the nanoparticles self-assemble into the final layer structure.

Role of Acetone in the Formation of Highly Dispersed Cationic Polystyrene Nanoparticles

Directory of Open Access Journals (Sweden)

Ernawati Lusi

2017-03-01

Full Text Available A modified emulsion polymerisation synthesis route for preparing highly dispersed cationic polystyrene (PS nanoparticles is reported. The combined use of 2,2′-azobis[2-(2-imidazolin- 2-ylpropane] di-hydrochloride (VA-044 as the initiator and acetone/water as the solvent medium afforded successful synthesis of cationic PS particles as small as 31 nm in diameter. A formation mechanism for the preparation of PS nanoparticles was proposed, whereby the occurrence of rapid acetone diffusion caused spontaneous rupture of emulsion droplets into smaller droplets. Additionally, acetone helped to reduce the surface tension and increase the solubility of styrene, thus inhibiting aggregation and coagulation among the particles. In contrast, VA-044 initiator could effectively regulate the stability of the PS nanoparticles including both the surface charge and size. Other reaction parameters i.e. VA-044 concentration and reaction time were examined to establish the optimum polymerisation conditions.

Polymer supported gold nanoparticles: Synthesis and characterization of functionalized polystyrene-supported gold nanoparticles and their application in catalytic oxidation of alcohols in water

Science.gov (United States)

Kaboudin, Babak; Khanmohammadi, Hamid; Kazemi, Foad

2017-12-01

Sulfonated polystyrene microsphere were functionalized using ethylene diamine to introduce amine groups to the polymer chains. The amine functionalized polymers were used as a support for gold nanoparticles. A thorough structural characterization has been carried out by means of transmission electron microscopy (TEM), scanning electron microscopy (SEM) images, EDS, CHN and atomic absorption spectroscopy. The polymer supported gold nanoparticles was found to be an efficient catalyst for the oxidation of alcohols in water.

The Role of Mucin in the Toxicological Impact of Polystyrene Nanoparticles

Directory of Open Access Journals (Sweden)

Iwona Inkielewicz-Stepniak

2018-05-01

Full Text Available The development of novel oral drug delivery systems is an expanding area of research and both new approaches for improving their efficacy and the investigation of their potential toxicological effect are crucial and should be performed in parallel. Polystyrene nanoparticles (NPs have been used for the production of diagnostic and therapeutic nanosystems, are widely used in food packaging, and have also served as models for investigating NPs interactions with biological systems. The mucous gel layer that covers the epithelium of the gastrointestinal system is a complex barrier-exchange system that it is mainly constituted by mucin and it constitutes the first physical barrier encountered after ingestion. In this study, we aimed to investigate the effect of polystyrene NPs on mucin and its potential role during NP–cell interactions. For this purpose, we evaluated the interaction of polystyrene NPs with mucin in dispersion by dynamic light scattering and with a deposited layer of mucin using a quartz crystal microbalance with dissipation technology. Next, we measured cell viability and the apoptotic state of three enterocyte-like cell lines that differ in their ability to produce mucin, after their exposure to the NPs. Positive charged NPs showed the ability to strongly interact and aggregate mucin in our model. Positive NPs affected cell viability and induced apoptosis in all cell lines independently of their ability of produce mucin.

Manufacturing and Morphological Analysis of Composite Material of Polystyrene Nanospheres/Cadmium Metal Nanoparticles

Directory of Open Access Journals (Sweden)

Pratama Jujur Wibawa

2013-03-01

Full Text Available A very simple nanocomposite material has been in-situ manufactured from an aqueous polystyrene nanospheres dispersion and cadmium (Cd metal nanoparticles. The manufacturing was performed by using a high frequency of 40 kHz ultrasonic (US agitation for 45 minute at atmospheric pressure and at room temperature 20 oC. No chemical reducing agent and surfactant added in this manufacturing technique due to the US could reduce Cd2+ ions of cadmium nitrate tetrahydrate to Cd atomic metals nanoparticles whereas water molecules could act as a pseudo stabilizer for the manufactured material. A thin film was manufactured from aqueous colloidal nanocomposite material of Polystyrene nanospheres/Cd metal nanoparticles (PSNs/CdMNp fabricated on a hydrophilic silicon wafer. The thin film was then characterized by a JEOL-FESEM for its surface morphology characteristic and by ATR-FTIR spectrometry for its molecular change investigation. It could be clearly observed that surface morphology of the thin film material was not significantly changed under 633 nm wavelength continuous laser radiation exposure for 20 minute. In addition, its ATR-FTIR spectra of wave number peaks around 3400 cm-1 have been totally disappeared under the laser exposure whereas that at around 699 cm-1 and 668 cm-1 have not been significantly changed. The first phenomenon indicated that the hydrogen bond existed in PSNs/CdMNp material was collapsed by the laser exposure. The second phenomena indicated that the PSNs phenyl ring moiety was not totally destroyed under the laser exposure. It was suspected due to the existence of Cd nanoparticles covered throughout the spherical surface of PSNs/CdMNp material particles. Therefore a nice model of material structure of the mentioned PSNs/CdMNp nanocomposite material could be suggested in this research. It could be concluded that this research have been performed since the material structure model of the manufactured PSNs/CdMNp nanocomposite could be

Synthesis and characterization of polystyrene coated iron oxide nanoparticles and asymmetric assemblies by phase inversion

KAUST Repository

Xie, Yihui

2014-09-02

Films with a gradient concentration of magnetic iron oxide nanoparticles are reported, based on a phase inversion membrane process. Nanoparticles with ∼13 nm diameter were prepared by coprecipitation in aqueous solution and stabilized by oleic acid. They were further functionalized by ATRP leading to grafted polystyrene brush. The final nanoparticles of 33 nm diameter were characterized by TGA, FTIR spectroscopy, GPC, transmission electron microscopy, and dynanmic light scattering. Asymmetric porous nanoparticle assemblies were then prepared by solution casting and immersion in water. The nanocomposite film production with functionalized nanoparticles is fast and technically scalable. The morphologies of films were characterized by scanning electron microscopy and atomic force microscopy, demonstrating the presence of sponge-like structures and finger-like cavities when 50 and 13 wt % casting solutions were, respectively, used. The magnetic properties were evaluated using vibrating sample magnetometer.

Synthesis and characterization of polystyrene embolization particles doped with tantalum oxide nanoparticles for X-ray contrast.

Science.gov (United States)

Morrison, Rachel; Thompson, James; Bird, Luke; Hill, Mark A; Townley, Helen

2015-08-01

Radiopaque and fluorescent embolic particles have been synthesized and characterised to match the size of vasculature found in tumours to ensure effective occlusion of the vessels. A literature search showed that the majority of vessels surrounding a tumour were less than 50 µm and therefore polydispersed polystyrene particles with a peak size of 50 µm have been synthesised. The embolic particles contain 5-8 nm amorphous tantalum oxide nanoparticles which provide X-ray contrast. Embolic particles containing up to 9.4 wt% tantalum oxide were prepared and showed significant contrast compared to the undoped polystyrene particles. The X-ray contrast of the embolic particles was shown to be linear (R(2) = 0.9) with respect to the concentration of incorporated tantalum nanoparticles. A model was developed which showed that seventy-five 50 µm embolic particles containing 10% tantalum oxide could provide the same contrast as 5 cm of bone. Therefore, the synthesized particles would provide sufficient X-ray contrast to enable visualisation within a tumour.

Rapid Synthesis of Highly Monodisperse Au x Ag 1− x Alloy Nanoparticles via a Half-Seeding Approach

KAUST Repository

Chng, Ting Ting

2011-05-03

Gold-silver alloy AuxAg1-x is an important class of functional materials promising new applications across a wide array of technological fields. In this paper, we report a fast and facile synthetic protocol for preparation of highly monodisperse AuxAg1-x alloy nanoparticles in the size range of 3-6 nm. The precursors employed in this work are M(I)-alkanethiolates (M = Au and Ag), which can be easily prepared by mixing common chemicals such as HAuCl4 or AgNO3 with alkanethiols at room temperature. In this half-seeding approach, one of the M(I)-alkanethiolates is first heated and reduced in oleylamine solvent, and freshly formed metal clusters will then act as premature seeds on which both the first and second metals (from M(I)-alkanethiolates, M = Au and Ag) can grow accordingly without additional nucleation and thus achieve high monodispersity for product alloy nanoparticles. Unlike in other prevailing methods, both Au and Ag elements present in these solid precursors are in the same monovalent state and have identical supramolecular structures, which may lead to a more homogeneous reduction and complete interdiffusion at elevated reaction temperatures. When the M(I)-alkanethiolates are reduced to metallic forms, the detached alkanethiolate ligands will serve as capping agent to control the growth. More importantly, composition, particle size, and optical properties of AuxAg1-x alloy nanoparticles can be conveniently tuned with this approach. The optical limiting properties of the prepared particles have also been investigated at 532 and 1064 nm using 7 ns laser pulses, which reveals that the as-prepared alloy nanoparticles exhibit outstanding broadband optical limiting properties with low thresholds. © 2011 American Chemical Society.

Synthesis of micro-sized polystyrene magnetic particles

International Nuclear Information System (INIS)

Neves, Juliete S.; Suarez, Paulo A.Z.; Umpierre, Alexandre P.; Machado, Fabricio; Souza Junior, Fernando G. de

2011-01-01

The present work illustrates the synthesis of spherical and micro-sized polystyrene magnetic particles by using a water-based suspension polymerization process to incorporate in situ surface modified superparamagnetic Fe 3 O 4 nanoparticles. The crystallite size of Fe 3 O 4 was determined to be equal to 7.7 nm, based on Scherrer's equation and XRD measurement. According to EDX analyses, Fe 3 O 4 / polystyrene nanocomposites particles show strong characteristic peaks Kα and Kβ of iron at the interval from 6.38 KeV to 7.04 KeV with an amount of iron in the samples equal to 98 %, indicating that the inorganic material dispersed in the polystyrene matrix is essentially Fe in the form of iron oxide (Fe 3 O 4 ). The obtained polymeric materials presented good magnetic behavior, indicating that the modified Fe 3 O 4 nanoparticles were successfully dispersed in the polystyrene particles. (author)

Facile preparation of monodisperse, impurity-free, and antioxidation copper nanoparticles on a large scale for application in conductive ink.

Science.gov (United States)

Zhang, Yu; Zhu, Pengli; Li, Gang; Zhao, Tao; Fu, Xianzhu; Sun, Rong; Zhou, Feng; Wong, Ching-ping

2014-01-08

Monodisperse copper nanoparticles with high purity and antioxidation properties are synthesized quickly (only 5 min) on a large scale (multigram amounts) by a modified polyol process using slightly soluble Cu(OH)2 as the precursor, L-ascorbic acid as the reductant, and PEG-2000 as the protectant. The resulting copper nanoparticles have a size distribution of 135 ± 30 nm and do not suffer significant oxidation even after being stored for 30 days under ambient conditions. The copper nanoparticles can be well-dispersed in an oil-based ink, which can be silk-screen printed onto flexible substrates and then converted into conductive patterns after heat treatment. An optimal electrical resistivity of 15.8 μΩ cm is achieved, which is only 10 times larger than that of bulk copper. The synthesized copper nanoparticles could be considered as a cheap and effective material for printed electronics.

Polystyrene nanoparticles affect Xenopus laevis development

Energy Technology Data Exchange (ETDEWEB)

Tussellino, Margherita; Ronca, Raffaele [University of Naples Federico II, Department of Biology (Italy); Formiggini, Fabio [Italian Institute of Technology, Center for Advanced Biomaterials for Health Care IIT@CRIB (Italy); Marco, Nadia De [University of Naples Federico II, Department of Biology (Italy); Fusco, Sabato; Netti, Paolo Antonio [Italian Institute of Technology, Center for Advanced Biomaterials for Health Care IIT@CRIB (Italy); Carotenuto, Rosa, E-mail: rosa.carotenuto@unina.it [University of Naples Federico II, Department of Biology (Italy)

2015-02-15

Exposing living organisms to nanoparticulates is potentially hazardous, in particular when it takes place during embryogenesis. In this investigation, we have studied the effects of 50-nm-uncoated polystyrene nanoparticles (PSNPs) as a model to investigate the suitability of their possible future employments. We have used the standardized Frog Embryo Teratogenesis Assay-Xenopus test during the early stages of larval development of Xenopus laevis, and we have employed either contact exposure or microinjections. We found that the embryos mortality rate is dose dependent and that the survived embryos showed high percentage of malformations. They display disorders in pigmentation distribution, malformations of the head, gut and tail, edema in the anterior ventral region, and a shorter body length compared with sibling untreated embryos. Moreover, these embryos grow more slowly than the untreated embryos. Expressions of the mesoderm markers, bra (T-box Brachyury gene), myod1 (myogenic differentiation1), and of neural crest marker sox9 (sex SRY (determining region Y-box 9) transcription factor sox9), are modified. Confocal microscopy showed that the nanoparticles are localized in the cytoplasm, in the nucleus, and in the periphery of the digestive gut cells. Our data suggest that PSNPs are toxic and show a potential teratogenic effect for Xenopus larvae. We hypothesize that these effects may be due either to the amount of NPs that penetrate into the cells and/or to the “corona” effect caused by the interaction of PSNPs with cytoplasm components. The three endpoints of our study, i.e., mortality, malformations, and growth inhibition, suggest that the tests we used may be a powerful and flexible bioassay in evaluating pollutants in aquatic embryos.

Polystyrene nanoparticles affect Xenopus laevis development

International Nuclear Information System (INIS)

Tussellino, Margherita; Ronca, Raffaele; Formiggini, Fabio; Marco, Nadia De; Fusco, Sabato; Netti, Paolo Antonio; Carotenuto, Rosa

2015-01-01

Exposing living organisms to nanoparticulates is potentially hazardous, in particular when it takes place during embryogenesis. In this investigation, we have studied the effects of 50-nm-uncoated polystyrene nanoparticles (PSNPs) as a model to investigate the suitability of their possible future employments. We have used the standardized Frog Embryo Teratogenesis Assay-Xenopus test during the early stages of larval development of Xenopus laevis, and we have employed either contact exposure or microinjections. We found that the embryos mortality rate is dose dependent and that the survived embryos showed high percentage of malformations. They display disorders in pigmentation distribution, malformations of the head, gut and tail, edema in the anterior ventral region, and a shorter body length compared with sibling untreated embryos. Moreover, these embryos grow more slowly than the untreated embryos. Expressions of the mesoderm markers, bra (T-box Brachyury gene), myod1 (myogenic differentiation1), and of neural crest marker sox9 (sex SRY (determining region Y-box 9) transcription factor sox9), are modified. Confocal microscopy showed that the nanoparticles are localized in the cytoplasm, in the nucleus, and in the periphery of the digestive gut cells. Our data suggest that PSNPs are toxic and show a potential teratogenic effect for Xenopus larvae. We hypothesize that these effects may be due either to the amount of NPs that penetrate into the cells and/or to the “corona” effect caused by the interaction of PSNPs with cytoplasm components. The three endpoints of our study, i.e., mortality, malformations, and growth inhibition, suggest that the tests we used may be a powerful and flexible bioassay in evaluating pollutants in aquatic embryos

DNA-imprinted polymer nanoparticles with monodispersity and prescribed DNA-strand patterns

Science.gov (United States)

Trinh, Tuan; Liao, Chenyi; Toader, Violeta; Barłóg, Maciej; Bazzi, Hassan S.; Li, Jianing; Sleiman, Hanadi F.

2018-02-01

As colloidal self-assembly increasingly approaches the complexity of natural systems, an ongoing challenge is to generate non-centrosymmetric structures. For example, patchy, Janus or living crystallization particles have significantly advanced the area of polymer assembly. It has remained difficult, however, to devise polymer particles that associate in a directional manner, with controlled valency and recognition motifs. Here, we present a method to transfer DNA patterns from a DNA cage to a polymeric nanoparticle encapsulated inside the cage in three dimensions. The resulting DNA-imprinted particles (DIPs), which are 'moulded' on the inside of the DNA cage, consist of a monodisperse crosslinked polymer core with a predetermined pattern of different DNA strands covalently 'printed' on their exterior, and further assemble with programmability and directionality. The number, orientation and sequence of DNA strands grafted onto the polymeric core can be controlled during the process, and the strands are addressable independently of each other.

Freezing polystyrene-b-poly(2-vinylpyridine) micelle nanoparticles with different nanostructures and sizes.

Science.gov (United States)

Fan, Hailong; Jin, Zhaoxia

2014-04-28

Herein we report how to control the nanostructures and sizes of polystyrene-b-poly(2-vinylpyridine) (PS-b-P2VP) nanoparticles via manipulating freezing in solvent-exchange. By characterizing and analyzing the distinct structural features of the obtained nanoparticles, we recognized that micelle self-assembly happens in the precipitation of PS-b-P2VP when water is added into the block copolymer (BCP) solution. Solvent properties significantly influence micelle types that are vesicles in acetone/H2O and spherical micelles in tetrahydrofuran/H2O, respectively, thus further inducing different frozen nanostructures of the obtained nanoparticles, onion-like in acetone/H2O and large compound micelles in tetrahydrofuran/H2O. By changing the concentration of the block copolymers and the Vsolvent/VH2O ratio to modify the freezing stage at which block copolymer micelles are frozen, we can further control the size of the nanoparticles. Moreover, small molecules (phosphotungstic acid, pyrene, 1-pyrenebutyric acid) can be trapped into the block copolymer nanoparticles via the freezing process. Their distribution in the nanoparticles relies not only on the solvent property, but also on their interactions with block copolymers. The hybrid nanoparticles with ordered distribution of small molecules can be further changed to partially-void nanoparticles. Our study demonstrated that manipulating the freezing of block copolymers in the solvent exchange process is a simple and controllable fabrication method to generate BCP nanoparticles with different architectures.

SERS efficiencies of micrometric polystyrene beads coated with gold and silver nanoparticles: the effect of nanoparticle size

International Nuclear Information System (INIS)

Mir-Simon, Bernat; Morla-Folch, Judit; Pazos-Perez, Nicolas; Xie, Hai-nan; Alvarez-Puebla, Ramon A; Guerrini, Luca; Gisbert-Quilis, Patricia; Bastús, Neus G; Puntes, Víctor

2015-01-01

Rapid advances in nanofabrication techniques of reproducibly manufacturing plasmonic substrates with well-defined nanometric scale features and very large electromagnetic enhancements paved the way for the final translation of the analytical potential of surface-enhanced Raman scattering (SERS) to real applications. A vast number of different SERS substrates have been reported in the literature. Among others, discrete particles consisting of an inorganic micrometric or sub-micrometric core homogeneously coated with plasmonic nanoparticles stand out for their ease of fabrication, excellent SERS enhancing properties, long-term optical stability and remarkable experimental flexibility (manipulation, storage etc). In this article, we performed a systematic experimental study of the correlation between the size of quasi-spherical gold and silver nanoparticle and the final optical property of their corresponding assembles onto micrometric polystyrene (PS) beads. The size and composition of nanoparticles play a key role in tuning the SERS efficiency of the hybrid material at a given excitation wavelength. This study provides valuable information for the selection and optimization of the appropriate PS@NPs substrates for the desired applications. (invited article)

Effect of surfactant amount on the morphology and magnetic properties of monodisperse ZnFe{sub 2}O{sub 4} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Zhao, Haitao, E-mail: zht95711lunwen@163.com; Liu, Ruiping; Zhang, Qiang; Wang, Qiao

2016-03-15

Graphical abstract: Polyol process to monodisperse ZnFe{sub 2}O{sub 4} nanoparticles. - Highlights: • An one-step, facile and inexpensive synthetic route to monodisperse ZnFe{sub 2}O{sub 4} nanoparticles is described. • The sodium citrate stabilized ZnFe{sub 2}O{sub 4} nanoparticles with a diameter in the 5–8 nm size range can be easily dispersed in water. • The synthesis is very robust in terms of variations of experimental parameters. • ZnFe{sub 2}O{sub 4} nanoparticles present ferrimagnetic behavior at room temperature with a small hysteresis. - Abstract: The spinel ZnFe{sub 2}O{sub 4} ferrites with sodium citrate as a surfactant were fabricated by polyol process. The effect of surfactant amount on the structure, morphology and magnetic properties of ZnFe{sub 2}O{sub 4} ferrites were investigated by X-ray diffraction(XRD), transmission electron microscope (TEM), thermogravimetric and differential scanning calorimetry (TG–DSC) and vibrating sample magnetometry (VSM), respectively. The results indicate that the structure of ZnFe{sub 2}O{sub 4} ferrites is a pure cubic spinel structure with a particle size of 5–8 nm. The dispersion of the synthesized ZnFe{sub 2}O{sub 4} is enhanced when the mole ratio of Fe(acac){sub 3} to sodium citrate decreases. The synthesized particles present ferrimagnetic behavior with a small hysteresis at room temperature. The increase of surfactant amount conversely leads to the decrease in the saturation magnetization value (Ms) especially when the mole ratio of Fe(acac){sub 3} to sodium citrate decreases to 8:3. Its Ms value is drastically reduced to 18.97 emu/g.

Design and Preparation of Cross-Linked Polystyrene Nanoparticles for Elastomer Reinforcement

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Ming Lu

2010-01-01

Full Text Available Cross-linked polystyrene (PS particles in a latex form were synthesized by free radical emulsion polymerization. The nano-PS-filled elastomer composites were prepared by the energy-saving latex compounding method. Results showed that the PS particles took a spherical shape in the size of 40–60 nm with a narrow size distribution, and the glass-transition temperature of the PS nanoparticles increased with the cross-linking density. The outcomes from the mechanical properties demonstrated that when filled into styrene-butadiene rubber (SBR, nitrile-butadiene rubber (NBR, and natural rubber (NR, the cross-linked PS nano-particles exhibited excellent reinforcing capabilities in all the three matrices, and the best in the SBR matrix. In comparison with that of the carbon black filled composites, another distinguished advantage of the cross-linked PS particles filled elastomer composites was found to be light weight in density, which could help to save tremendous amount of energy when put into end products.

Metal Fe3+ ions assisted synthesis of highly monodisperse Ag/SiO2 nanohybrids and their antibacterial activity

International Nuclear Information System (INIS)

Zhang, Nianchun; Xue, Feng; Yu, Xiang; Zhou, Huihua; Ding, Enyong

2013-01-01

Graphical abstract: TEM images of the Ag/SiO 2 -2 nanohybrids. The homogeneous and more mono-disperse Ag nanoparticles deposit on SiO 2 spheres. Through this method, Ag nanoparticles are easily formed on the surface of SiO 2 compared to other methods. Highlights: ► We prepared homogeneous and mono-dispersed Ag/SiO 2 -2 nanohybrids by adding Fe 3+ ions. ► The Ag/SiO 2 -2 nanohybrids had core(SiO 2 )-shell(Ag) structure. ► The Ag/SiO 2 -2 nanohybrids exhibited excellent antibacterial activity against bacteria. ► The reaction temperature was lower and the yield of Ag/SiO 2 -2 nanohybrids were higher. - Abstract: Highly monodispersed Ag/SiO 2 nanohybrids with excellent antibacterial property were synthesized by using DMF as a reducing agent and employing an additional redox potential of metal Fe 3+ ion as a catalytic agent. The obtained Ag/SiO 2 -2 nanohybrids of about 240 nm were highly monodispersity and uniformity by adding trace Fe 3+ ions into the reaction which Ag + reacted with N,N-dimethyl formamide (DMF) at 70 °C. Compared to the conventional techniques, which need long time and high temperature for silica coating of Ag nanoparticles, this new method was capable of synthesizing monodispersed, uniform, high yield Ag/SiO 2 nanohybrids. The electron was transferred from the Fe 2+ ion to the Ag + ion to accelerate the nucleation of silver nanoparticles. The chemical structures, morphologies and properties of the Ag/SiO 2 nanohybrids were characterized by X-ray diffraction (XRD), (High-resolution, Scanning transmission) transmission electron microscopy (TEM, HRTEM and STEM), and X-ray photoelectron spectroscopy (XPS), and UV–vis spectroscopy (UV–vis) and test of antibacterial. The results demonstrated that the silver nanoparticles supported on the surface of SiO 2 spheres in Ag/SiO 2 -2 nanohybrids structure, the Ag nanoparticles were homogeneous and monodispersed. The results also indicated that the Ag/SiO 2 -2 nanohybrid had excellent antibacterial.

Au-coated 3-D nanoporous titania layer prepared using polystyrene-b-poly(2-vinylpyridine) block copolymer nanoparticles.

Science.gov (United States)

Shin, Won-Jeong; Basarir, Fevzihan; Yoon, Tae-Ho; Lee, Jae-Suk

2009-04-09

New nanoporous structures of Au-coated titania layers were prepared by using amphiphilic block copolymer nanoparticles as a template. A 3-D template composed of self-assembled quaternized polystyrene-b-poly(2-vinylpyridine) (Q-PS-b-P2VP) block copolymer nanoparticles below 100 nm was prepared. The core-shell-type nanoparticles were well ordered three-dimensionally using the vertical immersion method on the substrate. The polar solvents were added to the polymer solution to prevent particle merging at 40 degrees C when considering the interaction between polymer nanoparticles and solvents. Furthermore, Au-coated PS-b-P2VP nanoparticles were prepared using thiol-capped Au nanoparticles (3 nm). The 3-D arrays with Au-coated PS-b-P2VP nanoparticles as a template contributed to the preparation of the nanoporous Au-coated titania layer. Therefore, the nanoporous Au-coated titania layer was fabricated by removing PS-b-P2VP block copolymer nanoparticles by oxygen plasma etching.

Nanospot soldering polystyrene nanoparticles with an optical fiber probe laser irradiating a metallic AFM probe based on the near-field enhancement effect.

Science.gov (United States)

Cui, Jianlei; Yang, Lijun; Wang, Yang; Mei, Xuesong; Wang, Wenjun; Hou, Chaojian

2015-02-04

With the development of nanoscience and nanotechnology for the bottom-up nanofabrication of nanostructures formed from polystyrene nanoparticles, joining technology is an essential step in the manufacturing and assembly of nanodevices and nanostructures in order to provide mechanical integration and connection. To study the nanospot welding of polystyrene nanoparticles, we propose a new nanospot-soldering method using the near-field enhancement effect of a metallic atomic force microscope (AFM) probe tip that is irradiated by an optical fiber probe laser. On the basis of our theoretical analysis of the near-field enhancement effect, we set up an experimental system for nanospot soldering; this approach is carried out by using an optical fiber probe laser to irradiate the AFM probe tip to sinter the nanoparticles, providing a promising technical approach for the application of nanosoldering in nanoscience and nanotechnology.

Reflection electron energy loss spectroscopy as efficient technique for the determination of optical properties of polystyrene intermixed with gold nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Deris, Jamileh [Department of Physics, Yasouj University, Yasouj 75918-74831 (Iran, Islamic Republic of); Hajati, Shaaker, E-mail: Hajati@mail.yu.ac.ir [Department of Physics, Yasouj University, Yasouj 75918-74831 (Iran, Islamic Republic of); Department of Semiconductors, Materials and Energy Research Center, Karaj 3177983634 (Iran, Islamic Republic of)

2017-01-15

Highlights: • Reflection Electron Energy Loss Spectroscopy of nano-metalized polymer. • Determination of real part of the dielectric function of nanostructured sample. • Determination of imaginary part of the dielectric function of nanostructured sample. • Determination of refractive index and coefficient of extinction of the sample. • Determination of reflection and absorption coefficients of nano-metalized Polymer. - Abstract: The electronic properties (electron inelastic cross section, energy loss function) of a nano-metalized polystyrene obtained by reflection electron energy loss spectroscopy (REELS) in a previous study [J. Deris, S. Hajati, S. Tougaard, V. Zaporojtchenko, Appl. Surf. Sci. 377 (2016) 44–47], which relies on the Yubero-Tougaard method, were used in the complementary application of Kramers-Kronig transformation to determine its optical properties such as the real part (ε{sub 1}) and imaginary part (ε{sub 2}) of the dielectric function (ε), refractive index (n), coefficients of extinction (k), reflection (R) and absorption (μ). The degree of intermixing of polystyrene thin film and gold nanoparticles of sizes 5.5 nm was controlled by annealing the sample to achieve a morphology in which the nanoparticles were homogeneously distributed within polystyrene. It is worth noting that no data are available on the optical properties of metalized polymers such as gold nanoparticles intermixed with polystyrene. Therefore, this work is of high importance in terms of both the sample studied here and the method applied. The advantage of the method applied here is that no information on the lateral distribution of the nanocomposite sample is required. This means that the REELS technique has been presented here to suitably, efficiently and easily obtain the optical properties of such nano-metalized polymer in which the metal nanoparticles have been vertically well distributed (homogeneous in depth). Therefore, for vertically homogeneous and

Synthesis of monodisperse MFe{sub 2}O{sub 4} (M = Fe and Zn) nanoparticles for polydiethylsiloxane-based ferrofluid with a solvothermal method

Energy Technology Data Exchange (ETDEWEB)

Wang, Wei [State Key Laboratory of Optoelectronic Materials and Technologies, Guangdong Provincial Key Laboratory of Photovoltaics Technologies, School of Physics and Engineering, Sun Yat-Sen University, Guangzhou 510275 (China); Laboratory of Nanophotonic Functional Materials and Devices, Institute of Optoelectronic Materials and Technology, South China Normal University, Guangzhou 510631 (China); Zhuang, Lin, E-mail: stszhl@mail.sysu.edu.cn [State Key Laboratory of Optoelectronic Materials and Technologies, Guangdong Provincial Key Laboratory of Photovoltaics Technologies, School of Physics and Engineering, Sun Yat-Sen University, Guangzhou 510275 (China); Zhang, Yong [Laboratory of Nanophotonic Functional Materials and Devices, Institute of Optoelectronic Materials and Technology, South China Normal University, Guangzhou 510631 (China); Shen, Hui [State Key Laboratory of Optoelectronic Materials and Technologies, Guangdong Provincial Key Laboratory of Photovoltaics Technologies, School of Physics and Engineering, Sun Yat-Sen University, Guangzhou 510275 (China)

2015-09-15

Highlights: • MFe{sub 2}O{sub 4} nanoparticles were synthesized through a facile solvothermal method. • The relationship between viscosity and temperature of the polydiethylsiloxane-based ferrofluid is discussed. • Fe{sub 3}O{sub 4} nanoparticles have a saturation magnetization of 73.06 emu/g at room temperature. - Abstract: Monodisperse MFe{sub 2}O{sub 4} (M = Fe, Zn) nanoparticles were successfully synthesized for the application of polydiethylsiloxane-based (PDES) ferrofluids (FFs) via a novel solvothermal method, with which 1-octanol and 1-octanamine act as binary solvent, oleic acid (OA) as the surfactant and metal acetylacetonate [M(acac){sub 3}](M = Fe and Zn) as the metal source. X-ray diffractometer confirms that the resultant nanoparticles are pure MFe{sub 2}O{sub 4} with a spinel structure. Infrared spectroscopy indicates that oleic acid is bound to the surface of MFe{sub 2}O{sub 4} through a covalent bond between carboxylate (COO{sup −}) and metal cations. The ratio of 1-octanol and 1-octanamine plays a key role in the formation of the sphere-shaped morphology. Transmission electron microscopy (TEM) images confirm that the Fe{sub 3}O{sub 4} particles are of 4–11 nm with good monodispersity and a narrow size distribution. The saturation magnetization of Fe{sub 3}O{sub 4} nanoparticles with sizes of 7 nm can reach up to 73.06 emu/g. Polydiethylsiloxane-based (PDES) FFs show relatively smaller changes of the viscosity with low temperatures (from −7 to 20 °C) than the polydimethylsiloxane-based (PDMS) FFs. For FFs applications, the relationship between viscosity and temperature is also discussed.

Epidermal Growth Factor Enhances Cellular Uptake of Polystyrene Nanoparticles by Clathrin-Mediated Endocytosis.

Science.gov (United States)

Phuc, Le Thi Minh; Taniguchi, Akiyoshi

2017-06-19

The interaction between nanoparticles and cells has been studied extensively, but most research has focused on the effect of various nanoparticle characteristics, such as size, morphology, and surface charge, on the cellular uptake of nanoparticles. In contrast, there have been very few studies to assess the influence of cellular factors, such as growth factor responses, on the cellular uptake efficiency of nanoparticles. The aim of this study was to clarify the effects of epidermal growth factor (EGF) on the uptake efficiency of polystyrene nanoparticles (PS NPs) by A431 cells, a human carcinoma epithelial cell line. The results showed that EGF enhanced the uptake efficiency of A431 cells for PS NPs. In addition, inhibition and localization studies of PS NPs and EGF receptors (EGFRs) indicated that cellular uptake of PS NPs is related to the binding of EGF-EGFR complex and PS NPs. Different pathways are used to enter the cells depending on the presence or absence of EGF. In the presence of EGF, cellular uptake of PS NPs is via clathrin-mediated endocytosis, whereas, in the absence of EGF, uptake of PS NPs does not involve clathrin-mediated endocytosis. Our findings indicate that EGF enhances cellular uptake of PS NPs by clathrin-mediated endocytosis. This result could be important for developing safe nanoparticles and their safe use in medical applications.

Epidermal Growth Factor Enhances Cellular Uptake of Polystyrene Nanoparticles by Clathrin-Mediated Endocytosis

Directory of Open Access Journals (Sweden)

Le Thi Minh Phuc

2017-06-01

Full Text Available The interaction between nanoparticles and cells has been studied extensively, but most research has focused on the effect of various nanoparticle characteristics, such as size, morphology, and surface charge, on the cellular uptake of nanoparticles. In contrast, there have been very few studies to assess the influence of cellular factors, such as growth factor responses, on the cellular uptake efficiency of nanoparticles. The aim of this study was to clarify the effects of epidermal growth factor (EGF on the uptake efficiency of polystyrene nanoparticles (PS NPs by A431 cells, a human carcinoma epithelial cell line. The results showed that EGF enhanced the uptake efficiency of A431 cells for PS NPs. In addition, inhibition and localization studies of PS NPs and EGF receptors (EGFRs indicated that cellular uptake of PS NPs is related to the binding of EGF–EGFR complex and PS NPs. Different pathways are used to enter the cells depending on the presence or absence of EGF. In the presence of EGF, cellular uptake of PS NPs is via clathrin-mediated endocytosis, whereas, in the absence of EGF, uptake of PS NPs does not involve clathrin-mediated endocytosis. Our findings indicate that EGF enhances cellular uptake of PS NPs by clathrin-mediated endocytosis. This result could be important for developing safe nanoparticles and their safe use in medical applications.

Template synthesis of highly crystalline and monodisperse iron oxide pigments of nanosize

International Nuclear Information System (INIS)

Sreeram, Kalarical Janardhanan; Indumathy, Ramasamy; Rajaram, Ananthanarayanan; Nair, Balachandran Unni; Ramasami, Thirumalachari

2006-01-01

Synthesis of highly crystalline and monodisperse iron oxide nanoparticles is reported. The separation of Fe centers through site-specific binding to a polysaccharide-alginate matrix enables the generation of particles with a monodisperse or narrow size distribution character, resulting in transparent pigments. Site-specific interactions coupled with gel like character of alginate is proposed as the mechanism behind generation of lower particle sizes. Alginate-Fe complexes developed were subjected to heat treatment to provide for crystalline character and development of hematite (α-Fe 2 O 3 ). Conditions most ideal for achieving monodispersity and lower sizes have been optimized and confirmed through microscopic and photon correlation spectroscopic measurements

Preparation and characterization of nanocomposites of natural rubber with polystyrene and styrene-methacrylic acid copolymer nanoparticles

Directory of Open Access Journals (Sweden)

T. Nuruk

2012-06-01

Full Text Available Composites of natural rubber (NR/vinyl polymer nanoparticles as polystyrene (PS and poly(styrenemethacrylic acid (P(S-MAA were prepared by heterocoagulation technique. The polymer nanoparticles were prepared by emulsifier-free emulsion polymerizations at 70°C using potassium persulfate as initiator. Under acidic condition where positive charge was present on the NR latex (NRL surface, the nanoparticles having negative charge mainly from sulfate group of initiator were able to adsorb on the NRL surface, the electrostatic interaction being the driving force. The scanning electron micrographs showed that the polymer nanoparticles are homogenously distributed throughout NR matrix as nanoclusters with an average size of about 500 and 200 nm for PS and P(S-MAA, respectively. The mechanical properties of NR/PS and NR/P(S-MAA composite films were compared with the NR host. The nanocomposites, particularly when the polymer nanoparticles are uniformly dispersed, possess significantly enhanced mechanical properties strongly depending on the morphology of the nanocomposites.

Large-scale synthesis of monodisperse SiC nanoparticles with adjustable size, stoichiometric ratio and properties by fluidized bed chemical vapor deposition

Energy Technology Data Exchange (ETDEWEB)

Liu, Rongzheng; Liu, Malin, E-mail: liumalin@tsinghua.edu.cn; Chang, Jiaxing [Tsinghua University, Institute of Nuclear and New Energy Technology, Collaborative Innovation Center of Advanced Nuclear Energy Technology (China)

2017-02-15

A facile fluidized bed chemical vapor deposition method was proposed for the synthesis of monodisperse SiC nanoparticles by using the single precursor of hexamethyldisilane (HMDS). SiC nanoparticles with average particle size from 10 to 200 nm were obtained by controlling the temperature and the gas ratio. An experimental chemical vapor deposition phase diagram of SiC in the HMDS-Ar-H{sub 2} system was obtained and three regions of SiC-Si, SiC and SiC-C can be distinguished. The BET surface area and the photoluminescence properties of the SiC nanoparticles can be adjusted by changing the nanoparticle size. For the SiC nanospheres with free carbon, a novel hierarchical structure with 5 ~ 8 nm SiC nanoparticles embedded into the graphite matrix was obtained. The advantages of fluidized bed technology for the preparation of SiC nanoparticles were proposed based on the features of homogenous reaction zone, narrow temperature distribution, ultra-short reactant residence time and mass production.

Large-scale synthesis of monodisperse SiC nanoparticles with adjustable size, stoichiometric ratio and properties by fluidized bed chemical vapor deposition

International Nuclear Information System (INIS)

Liu, Rongzheng; Liu, Malin; Chang, Jiaxing

2017-01-01

A facile fluidized bed chemical vapor deposition method was proposed for the synthesis of monodisperse SiC nanoparticles by using the single precursor of hexamethyldisilane (HMDS). SiC nanoparticles with average particle size from 10 to 200 nm were obtained by controlling the temperature and the gas ratio. An experimental chemical vapor deposition phase diagram of SiC in the HMDS-Ar-H_2 system was obtained and three regions of SiC-Si, SiC and SiC-C can be distinguished. The BET surface area and the photoluminescence properties of the SiC nanoparticles can be adjusted by changing the nanoparticle size. For the SiC nanospheres with free carbon, a novel hierarchical structure with 5 ~ 8 nm SiC nanoparticles embedded into the graphite matrix was obtained. The advantages of fluidized bed technology for the preparation of SiC nanoparticles were proposed based on the features of homogenous reaction zone, narrow temperature distribution, ultra-short reactant residence time and mass production.

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

International Nuclear Information System (INIS)

Balasubramanian, Balamurugan; Kraemer, Kristin L; Valloppilly, Shah R; Ducharme, Stephen; Sellmyer, David J

2011-01-01

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 TiO 2 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) molecules using a thermal evaporation source, prior to deposition as TiO 2 -VDFO nanocomposite films on suitable substrates. The molecular coatings on TiO 2 nanoparticles serve two purposes, namely to prevent the TiO 2 nanoparticles from contacting each other and to couple the nanoparticle polarization to the matrix. Parallel-plate capacitors made of TiO 2 -VDFO nanocomposite film as the dielectric exhibit minimum dielectric dispersion and low dielectric loss. Dielectric measurements also show an enhanced effective dielectric constant in TiO 2 -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.

Inhibition of Neuroblastoma cancer cells viability by ferromagnetic Mn doped CeO_2 monodisperse nanoparticles mediated through reactive oxygen species

International Nuclear Information System (INIS)

Abbas, Fazal; Jan, Tariq; Iqbal, Javed; Haider Naqvi, M. Sajjad; Ahmad, Ishaq

2016-01-01

Here we report the Mn doping induced effects on structural, Raman, optical, magnetic and anticancer properties of CeO_2 nanoparticles prepared via soft chemical route. Structural and microstructural results infer that the synthesized nanoparticles have single phase cubic fluorite structure of CeO_2 and that Mn doping results in enhancement of the structural defects. Scanning electron microscopy results reveal the formation of monodisperse nanoparticles having average particle size ranging from 30 to 41 nm. The optical absorbance spectroscopy analysis discloses the band gap energy tailoring of CeO_2 nanoparticles via Mn doping. Room temperature ferromagnetism (RTFM) has been found in both as-prepared and Mn doped CeO_2 nanoparticles. This RTFM of the synthesized nanoparticles have been attributed to the Mn ions and surface defects such as oxygen vacancies. Finally, the influence of Mn dopant on the cell viability and reactive oxygen species (ROS) generation levels of CeO_2 nanoparticles in the presence of healthy and cancerous cells have been studied. It has been observed that the differential cytotoxicity of the synthesized nanoparticles is strongly correlated with level of ROS generation. - Highlights: • Mn doped CeO_2 nanoparticles with cubic fluorite structure were synthesized. • Mn dopant significantly tailored the band gap of CeO_2 nanoparticles. • The synthesized nanoparticles exhibited room temperature ferromagnetic behavior. • The cytotoxicity of these nanoparticles was reported for the first time. • The synthesized nanoparticles exhibited differential cytotoxicity.

Solid-Phase Immunoassay of Polystyrene-Encapsulated Semiconductor Coreshells for Cardiac Marker Detection

Directory of Open Access Journals (Sweden)

Sanghee Kim

2012-01-01

Full Text Available A solid-phase immunoassay of polystyrene-encapsulated semiconductor nanoparticles was demonstrated for cardiac troponin I (cTnI detection. CdSe/ZnS coreshells were encapsulated with a carboxyl-functionalized polystyrene nanoparticle to capture the target antibody through a covalent bonding and to eliminate the photoblinking and toxicity of semiconductor luminescent immunosensor. The polystyrene-encapsulated CdSe/ZnS fluorophores on surface-modified glass chip identified cTnI antigens at the level of ~ng/mL. It was an initial demonstration of diagnostic chip for monitoring a cardiovascular disease.

Novel one-step route for synthesizing CdS/polystyrene nanocomposite hollow spheres.

Science.gov (United States)

Wu, Dazhen; Ge, Xuewu; Zhang, Zhicheng; Wang, Mozhen; Zhang, Songlin

2004-06-22

CdS/polystyrene nanocomposite hollow spheres with diameters between 240 and 500 nm were synthesized under ambient conditions by a novel microemulsion method in which the polymerization of styrene and the formation of CdS nanoparticles were initiated by gamma-irradiation. The product was characterized by transmission electron microscopy (TEM), field-emission scanning electron microscopy (FESEM), X-ray powder diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric analysis (TGA), which show the walls of the hollow spheres are porous and composed of polystyrene containing homogeneously dispersed CdS nanoparticles. The quantum-confined effect of the CdS/polystyrene nanocomposite hollow spheres is confirmed by the ultraviolet-visible (UV-vis) and photoluminescent (PL) spectra. We propose that the walls of these nanocomposite hollow spheres originate from the simultaneous synthesis of polystyrene and CdS nanoparticles at the interface of microemulsion droplets. This novel method is expected to produce various inorganic/polymer nanocomposite hollow spheres with potential applications in the fields of materials science and biotechnology.

Water- and organo-dispersible gold nanoparticles supported by using ammonium salts of hyperbranched polystyrene: preparation and catalysis.

Science.gov (United States)

Gao, Lei; Nishikata, Takashi; Kojima, Keisuke; Chikama, Katsumi; Nagashima, Hideo

2013-12-01

Gold nanoparticles (1 nm in size) stabilized by ammonium salts of hyperbranched polystyrene are prepared. Selection of the R groups provides access to both water- and organo-dispersible gold nanoparticles. The resulting gold nanoparticles are subjected to studies on catalysis in solution, which include reduction of 4-nitrophenol with sodium borohydride, aerobic oxidation of alcohols, and homocoupling of phenylboronic acid. In the reduction of 4-nitrophenol, the catalytic activity is clearly dependent on the size of the gold nanoparticles. For the aerobic oxidation of alcohols, two types of biphasic oxidation are achieved: one is the catalyst dispersing in the aqueous phase, whereas the other is in the organic phase. The catalysts are reusable more than four times without loss of the catalytic activity. Selective synthesis of biphenyl is achieved by the homocoupling of phenylboronic acid catalyzed by organo-dispersible gold nanoparticles. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Polystyrene-Core, Silica-Shell Scintillant Nanoparticles for Low-Energy Radionuclide Quantification in Aqueous Media.

Science.gov (United States)

Janczak, Colleen M; Calderon, Isen A C; Mokhtari, Zeinab; Aspinwall, Craig A

2018-02-07

β-particle emitting radionuclides are useful molecular labels due to their abundance in biomolecules. Detection of β-emission from 3 H, 35 S, and 33 P, important biological isotopes, is challenging due to the low energies (E max ≤ 300 keV) and short penetration depths (≤0.6 mm) in aqueous media. The activity of biologically relevant β-emitters is usually measured in liquid scintillation cocktail (LSC), a mixture of energy-absorbing organic solvents, surfactants, and scintillant fluorophores, which places significant limitations on the ability to acquire time-resolved measurements directly in aqueous biological systems. As an alternative to LSC, we developed polystyrene-core, silica-shell nanoparticle scintillators (referred to as nanoSCINT) for quantification of low-energy β-particle emitting radionuclides directly in aqueous solutions. The polystyrene acts as an absorber for energy from emitted β-particles and can be loaded with a range of hydrophobic scintillant fluorophores, leading to photon emission at visible wavelengths. The silica shell serves as a hydrophilic shield for the polystyrene core, enabling dispersion in aqueous media and providing better compatibility with water-soluble analytes. While polymer and inorganic scintillating microparticles are commercially available, their large size and/or high density complicates effective dispersion throughout the sample volume. In this work, nanoSCINT nanoparticles were prepared and characterized. nanoSCINT responds to 3 H, 35 S, and 33 P directly in aqueous solutions, does not exhibit a change in scintillation response between pH 3.0 and 9.5 or with 100 mM NaCl, and can be recovered and reused for activity measurements in bulk aqueous samples, demonstrating the potential for reduced production of LSC waste and reduced total waste volume during radionuclide quantification. The limits of detection for 1 mg/mL nanoSCINT are 130 nCi/mL for 3 H, 8 nCi/mL for 35 S, and <1 nCi/mL for 33 P.

Monodispersed macroporous architecture of nickel-oxide film as an anode material for thin-film lithium-ion batteries

International Nuclear Information System (INIS)

Wu, Mao-Sung; Lin, Ya-Ping

2011-01-01

A nickel-oxide film with monodispersed open macropores was prepared on a stainless-steel substrate by electrophoretic deposition of a polystyrene-sphere monolayer followed by anodic electrodeposition of nickel oxy-hydroxide. The deposited films convert to cubic nickel oxide after annealing at 400 o C for 1 h. Galvanostatic charge and discharge results indicate that the nickel-oxide film with monodispersed open macropores is capable of delivering a higher capacity than the bare nickel-oxide film, especially in high-rate charge and discharge processes. The lithiation capacity of macroporous nickel oxide reaches 1620 mA h g -1 at 1 C current discharge and decreases to 990 mA h g -1 at 15 C current discharge. The presence of monodispersed open macropores in the nickel-oxide film might facilitate the electrolyte penetration, diffusion, and migration. Electrochemical reactions between nickel oxide and lithium ions are therefore markedly improved by this tailored film architecture.

Enhanced visible light photocatalytic properties of Fe-doped TiO2 nanorod clusters and monodispersed nanoparticles

International Nuclear Information System (INIS)

Liu, Y.; Wei, J.H.; Xiong, R.; Pan, C.X.; Shi, J.

2011-01-01

In order to get photocatalysts with desired morphologies and enhanced visible light responses, the Fe-doped TiO 2 nanorod clusters and monodispersed nanoparticles were prepared by modified hydrothermal and solvothermal method, respectively. The microstructures and morphologies of TiO 2 crystals can be controlled by restraining the hydrolytic reaction rates. The Fe-doped photocatalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis absorption spectroscopy (UV-vis), N 2 adsorption-desorption measurement (BET), and photoluminescence spectroscopy (PL). The refinements of the microstructures and morphologies result in the enhancement of the specific surface areas. The Fe 3+ -dopants in TiO 2 lattices not only lead to the significantly extending of the optical responses from UV to visible region but also diminish the recombination rates of the electrons and holes. The photocatalytic activities were evaluated by photocatalytic decomposition of formaldehyde in air under visible light illumination. Compared with P25 (TiO 2 ) and N-doped TiO 2 nanoparticles, the Fe-doped photocatalysts show high photocatalytic activities under visible light.

Characterization of Monodispersed Iron Oxide Nanocrystals by XAS and MCD measurement

International Nuclear Information System (INIS)

Kim, J.-Y.; Noh, H.-J.; Park, B.-G.; Kim, T.-Y.; Park, J.-H.; Hyeon, T.; Park, J.; Kang, E.

2004-01-01

Full text: Nanoparticles have attracted so much attention because of their potential technological applications and abundance of scientifically interesting issues. In particular, magnetic nanoparticles are considered to be applicable to various magnetic devices such as terabit memory, ferrofluids, magnetocaloric refrigeration systems, blood cells, etc. With the development of nano-technology, variation of physical properties as a function of particle size is one of the most important issues, but has been rarely explored because of difficulty of the size control in synthesizing nanoparticles. Recently, some of us successfully synthesized high crystalline and monodisperse maghemite nanoparticles without a size selection process and research in this field seems to be promoted by one step. In this report, we present a systematic characterization of the monodispersed nanocrystalline γ - Fe 2 O 3 with the diameter of 13, 8 and 4 nm by measuring the x-ray absorption spectroscopy (XAS) and the x-ray magnetic circular dichroism(XMCD) spectra on Fe L edge. The spectra of the 4 nm nanoparticles are very similar to those of maghemite (γ - Fe 2 O 3 ). However, the spectra become close to those of magnetite (Fe 3 O 4 ) as the particle size becomes 8 and 13 nm. Considering that the maghemite and magnetite have the same spinel structure with different Fe vacancies, these results can be explained that the surface of nanoparticles has more vacancies than the core part, indicating that surface disorder increases as the particle size decreases

Morphological investigation of polydisperse asymmetric block copolymer systems of poly(styrene) and poly(methacrylic acid) in the strong segregation regime

DEFF Research Database (Denmark)

Asad Ayoubi, Mehran; Zhu, Kaizheng; Nyström, Bo

2013-01-01

Samples of compositionally (highly) asymmetric diblock copolymers and, also, mixtures of diblock and triblock copolymers (the latter obtained as end-coupling products of two diblock molecules of the mixture), composed of (a) monodisperse majority block(s) of poly(styrene) (PS) and a polydisperse...

Local Segmental Dynamics and Stresses in Polystyrene - C$_{60}$ Mixtures

OpenAIRE

Vogiatzis, Georgios G.; Theodorou, Doros N.

2014-01-01

The polymer dynamics of homogeneous C$_{60}$-polystyrene mixtures in the molten state are studied via molecular simulations using two interconnected levels of representation for polystyrene nanocomposites: (a) A coarse-grained representation, in which each polystyrene repeat unit is mapped into a single "superatom" and each fullerene is viewed as a spherical shell. Equilibration of coarse-grained polymer-nanoparticle systems at all length scales is achieved via connectivity-altering Monte Car...

Green synthesis and antimicrobial activity of monodisperse silver nanoparticles synthesized using Ginkgo Biloba leaf extract

Energy Technology Data Exchange (ETDEWEB)

Ren, Yan-yu [School of Food and Biological Engineering, Shaanxi University of Science & Technology, Xi' an 710021 (China); Yang, Hui, E-mail: 549456369@qq.com [School of Food and Biological Engineering, Shaanxi University of Science & Technology, Xi' an 710021 (China); Wang, Tao [School of Food and Biological Engineering, Shaanxi University of Science & Technology, Xi' an 710021 (China); Wang, Chuang [Department of Highway & Bridge, Shaanxi Railway Institute, Weinan 714000 (China)

2016-11-25

Various parts of plants can be used as a raw material for the synthesis of nanoparticles, which is eco-friendly way and does not involve any harmful chemicals. In this project, Ginkgo biloba leaf, an abundantly available medicinal plant in China, was for the first time adopted as a reducing and stabilizing agent to synthesize smaller sized and stable silver nanoparticles (AgNPs). To improve the quality of AgNPs, the reduction was accelerated by changing the concentrations of initial Ag{sup +} (0.02, 0.04, 0.06 and 0.08 mol/L) of the reaction mixture consisting of silver nitrate solution (AgNO{sub 3}) and Ginkgo biloba leaf extract. At pH = 8 and lower AgNO{sub 3} concentration (0.02 mol/L), a colloid consisting of well-dispersed spherical nanoparticles was obtained. The synthesized nanocrystals were successfully characterized by UV–vis and XRD. TEM images revealed the size of the spherical AgNPs ranged between 10–16 nm. FTIR analysis revealed that biological macromolecules with groups of −NH{sub 2}, −OH, and others were distributed on the surface of the nanoparticles. The biosynthesized AgNPs exhibited good antibacterial activities against gram-negative bacteria and gram-positive bacteria. Compared to traditional chemical methods, Ginkgo biloba leaf extract provides an easy green synthetical way. It is anticipated that the biosynthesized AgNPs can be used in areas such as cosmetics, foods and medical applications. - Highlights: • Monodisperse silver nanoparticles were first prepared by a green synthetical way through Ginkgo Biloba leaf extract. • The synthesized AgNPs is of high crystallinity, stable and good dispersion with smaller sizes between 10–16 nm. • The achieved AgNPs exhibits good antibacterial activities. • The biosynthesis method is advantageous for its cost effectiveness, availability, portability, nontoxic and environmentally benign.

Green synthesis and antimicrobial activity of monodisperse silver nanoparticles synthesized using Ginkgo Biloba leaf extract

International Nuclear Information System (INIS)

Ren, Yan-yu; Yang, Hui; Wang, Tao; Wang, Chuang

2016-01-01

Various parts of plants can be used as a raw material for the synthesis of nanoparticles, which is eco-friendly way and does not involve any harmful chemicals. In this project, Ginkgo biloba leaf, an abundantly available medicinal plant in China, was for the first time adopted as a reducing and stabilizing agent to synthesize smaller sized and stable silver nanoparticles (AgNPs). To improve the quality of AgNPs, the reduction was accelerated by changing the concentrations of initial Ag + (0.02, 0.04, 0.06 and 0.08 mol/L) of the reaction mixture consisting of silver nitrate solution (AgNO 3 ) and Ginkgo biloba leaf extract. At pH = 8 and lower AgNO 3 concentration (0.02 mol/L), a colloid consisting of well-dispersed spherical nanoparticles was obtained. The synthesized nanocrystals were successfully characterized by UV–vis and XRD. TEM images revealed the size of the spherical AgNPs ranged between 10–16 nm. FTIR analysis revealed that biological macromolecules with groups of −NH 2 , −OH, and others were distributed on the surface of the nanoparticles. The biosynthesized AgNPs exhibited good antibacterial activities against gram-negative bacteria and gram-positive bacteria. Compared to traditional chemical methods, Ginkgo biloba leaf extract provides an easy green synthetical way. It is anticipated that the biosynthesized AgNPs can be used in areas such as cosmetics, foods and medical applications. - Highlights: • Monodisperse silver nanoparticles were first prepared by a green synthetical way through Ginkgo Biloba leaf extract. • The synthesized AgNPs is of high crystallinity, stable and good dispersion with smaller sizes between 10–16 nm. • The achieved AgNPs exhibits good antibacterial activities. • The biosynthesis method is advantageous for its cost effectiveness, availability, portability, nontoxic and environmentally benign.

Radiosynthesis and in vitro evaluation of the polystyrene particles as a promising probe in biomedical sciences

International Nuclear Information System (INIS)

Chen Jianmin; Tan Mingguang; Wu Yuanfang; Zhang Guilin; Li Yan

2005-01-01

Polystyrene particles with precise monodisperse particle size distributions ranging from 20nm to 90μm is now commercially available and it has very useful and versatile applications in many life sciences research fields. A simple direct labeling method was used to synthesis the iodinated ultrafine polystyrene particles. The assay of X-ray photoelectron spectroscopy(XPS) as well as Fourier Transform Infrared Spectroscopy (FTIR) indicated the formation of stable covalent bond to aryl group of the polymer particles. The purified radiosynthesis product was incubated with serum of rat, and then evaluated by in vitro stability test. The result showed that radioiodinated ultrafine polystyrene particles were largely unmetablized at 2 hours post-exposure, indicating the potential useful application of this widely used polymer particles as a promising probe in biomedical and pharmaceutical sciences.

Preparation and unique electrical behaviors of monodispersed hybrid nanorattles of metal nanocores with hairy electroactive polymer shells.

Science.gov (United States)

Cai, Tao; Zhang, Bin; Chen, Yu; Wang, Cheng; Zhu, Chun Xiang; Neoh, Koon-Gee; Kang, En-Tang

2014-03-03

A versatile template-assisted strategy for the preparation of monodispersed rattle-type hybrid nanospheres, encapsulating a movable Au nanocore in the hollow cavity of a hairy electroactive polymer shell (Au@air@PTEMA-g-P3HT hybrid nanorattles; PTEMA: poly(2-(thiophen-3-yl)ethyl methacrylate; P3HT: poly(3-hexylthiophene), was reported. The Au@silica core-shell nanoparticles, prepared by the modified Stöber sol-gel process on Au nanoparticle seeds, were used as templates for the synthesis of Au@silica@PTEMA core-double shell nanospheres. Subsequent oxidative graft polymerization of 3-hexylthiophene from the exterior surface of the Au@silica@PTEMA core-double shell nanospheres allowed the tailoring of surface functionality with electroactive P3HT brushes (Au@silica@PTEMA-g-P3HT nanospheres). The Au@air@ PTEMA-g-P3HT hybrid nanorattles were obtained after etching of the silica interlayer by HF. The as-prepared nanorattles were dispersed into an electrically insulating polystyrene matrix and for the first time used to fabricate nonvolatile memory devices. As a result, unique electrical behaviors, including insulator behavior, write-once-read-many-times and rewritable memory effects, and conductor behavior as well, were observed in the Al/Au@air@PTEMA-g-P3HT+PS/ITO (ITO: indium-tin oxide) sandwich thin-film devices. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Inhibition of Neuroblastoma cancer cells viability by ferromagnetic Mn doped CeO{sub 2} monodisperse nanoparticles mediated through reactive oxygen species

Energy Technology Data Exchange (ETDEWEB)

Abbas, Fazal; Jan, Tariq [Laboratory of Nanoscience and Technology (LNT), Department of Physics, International Islamic University Islamabad (Pakistan); Iqbal, Javed, E-mail: javed.saggu@iiu.edu.pk [Laboratory of Nanoscience and Technology (LNT), Department of Physics, International Islamic University Islamabad (Pakistan); Haider Naqvi, M. Sajjad [Department of Biochemistry, University of Karachi, Karachi (Pakistan); Ahmad, Ishaq [Experimental Physics Labs, National Center for Physics, Islamabad (Pakistan)

2016-04-15

Here we report the Mn doping induced effects on structural, Raman, optical, magnetic and anticancer properties of CeO{sub 2} nanoparticles prepared via soft chemical route. Structural and microstructural results infer that the synthesized nanoparticles have single phase cubic fluorite structure of CeO{sub 2} and that Mn doping results in enhancement of the structural defects. Scanning electron microscopy results reveal the formation of monodisperse nanoparticles having average particle size ranging from 30 to 41 nm. The optical absorbance spectroscopy analysis discloses the band gap energy tailoring of CeO{sub 2} nanoparticles via Mn doping. Room temperature ferromagnetism (RTFM) has been found in both as-prepared and Mn doped CeO{sub 2} nanoparticles. This RTFM of the synthesized nanoparticles have been attributed to the Mn ions and surface defects such as oxygen vacancies. Finally, the influence of Mn dopant on the cell viability and reactive oxygen species (ROS) generation levels of CeO{sub 2} nanoparticles in the presence of healthy and cancerous cells have been studied. It has been observed that the differential cytotoxicity of the synthesized nanoparticles is strongly correlated with level of ROS generation. - Highlights: • Mn doped CeO{sub 2} nanoparticles with cubic fluorite structure were synthesized. • Mn dopant significantly tailored the band gap of CeO{sub 2} nanoparticles. • The synthesized nanoparticles exhibited room temperature ferromagnetic behavior. • The cytotoxicity of these nanoparticles was reported for the first time. • The synthesized nanoparticles exhibited differential cytotoxicity.

Synthesis of magnetic hollow silica using polystyrene bead as a template

International Nuclear Information System (INIS)

Wu, W.; Caruntu, D.; Martin, A.; Yu, M.H.; O'Connor, C.J.; Zhou, W.L.; Chen, J.-F.

2007-01-01

In this paper, we report a new route to synthesize novel magnetic hollow silica nanospheres (MHSNs) using polystyrene particles as sacrificial templates, and TEOS and Fe 3 O 4 as precursors. TEM, EDS, XRD, and SQUID were applied to characterize MHSNs. TEM and EDS results show that the MHSNs consist of about 200 nm of hollow cores and ∼35 nm shells with ∼10 nm of Fe 3 O 4 nanoparticles embedded. The polystyrene beads were successfully removed by immersing the as-prepared silica nanocomposite in a toluene solution. XRD results demonstrate that the Fe 3 O 4 magnetic nanoparticles still keep spinel structure even heated at low temperature. The surface status of the polystyrene beads and Fe 3 O 4 nanoparticles has an important effect on the formation of the MHSNs. The MHSNs present a superparamagnetism at room temperature by SQUID measurement. The MHSNs have potential applications in biosystem and nanomedicine

Differences in the adsorption behaviour of poly(ethylene oxide) copolymers onto model polystyrene nanoparticles assessed by isothermal titration microcalorimetry correspond to the biological differences.

Science.gov (United States)

Stolnik, S; Heald, C R; Garnett, M G; Illum, L; Davis, S S

2005-01-01

The adsorption behaviour of a tetrafunctional copolymer of poly (ethylene oxide)-poly (propylene oxide) ethylene diamine (commercially available as Poloxamine 908) and a diblock copolymer of poly (lactic acid)-poly (ethylene oxide) (PLA/PEG 2:5) onto a model colloidal drug carrier (156 nm sized polystyrene latex) is described. The adsorption isotherm, hydrodynamic thickness of the adsorbed layers and enthalpy of the adsorption were assessed. The close similarity in the conformation of the poly (ethylene oxide) (PEO) chains (molecular weight 5,000 Da) in the adsorbed layers of these two copolymers was demonstrated by combining the adsorption data with the adsorbed layer thickness data. In contrast, the results from isothermal titration microcalorimetry indicated a distinct difference in the interaction of the copolymers with the polystyrene colloid surface. Poloxamine 908 adsorption to polystyrene nanoparticles is dominated by an endothermic heat effect, whereas, PLA/PEG 2:5 adsorption is entirely an exothermic process. This difference in adsorption behaviour could provide an explanation for differences in the biodistribution of Poloxamine 908 and PLA/PEG 2:5 coated polystyrene nanoparticles observed in previous studies. A comparison with the interaction enthalpy for several other PEO-containing copolymers onto the same polystyrene colloid was made. The results demonstrate the importance of the nature of the anchoring moiety on the interaction of the adsorbing copolymer with the colloid surface. An endothermic contribution is found when an adsorbing molecule contains a poly (propylene oxide) (PPO) moiety (e.g. Poloxamine 908), whilst the adsorption is exothermic (i.e. enthalpy driven) for PEO copolymers with polylactide (PLA/PEG 2:5) or alkyl moieties.

Monodisperse metal nanoparticle catalysts on silica mesoporous supports: synthesis, characterizations, and catalytic reactions

Energy Technology Data Exchange (ETDEWEB)

Somorjai, G.A.

2009-09-14

The design of high performance catalyst achieving near 100% product selectivity at maximum activity is one of the most important goals in the modern catalytic science research. To this end, the preparation of model catalysts whose catalytic performances can be predicted in a systematic and rational manner is of significant importance, which thereby allows understanding of the molecular ingredients affecting the catalytic performances. We have designed novel 3-dimensional (3D) high surface area model catalysts by the integration of colloidal metal nanoparticles and mesoporous silica supports. Monodisperse colloidal metal NPs with controllable size and shape were synthesized using dendrimers, polymers, or surfactants as the surface stabilizers. The size of Pt, and Rh nanoparticles can be varied from sub 1 nm to 15 nm, while the shape of Pt can be controlled to cube, cuboctahedron, and octahedron. The 3D model catalysts were generated by the incorporation of metal nanoparticles into the pores of mesoporous silica supports via two methods: capillary inclusion (CI) and nanoparticle encapsulation (NE). The former method relies on the sonication-induced inclusion of metal nanoparticles into the pores of mesoporous silica, whereas the latter is performed by the encapsulation of metal nanoparticles during the hydrothermal synthesis of mesoporous silica. The 3D model catalysts were comprehensively characterized by a variety of physical and chemical methods. These catalysts were found to show structure sensitivity in hydrocarbon conversion reactions. The Pt NPs supported on mesoporous SBA-15 silica (Pt/SBA-15) displayed significant particle size sensitivity in ethane hydrogenolysis over the size range of 1-7 nm. The Pt/SBA-15 catalysts also exhibited particle size dependent product selectivity in cyclohexene hydrogenation, crotonaldehyde hydrogenation, and pyrrole hydrogenation. The Rh loaded SBA-15 silica catalyst showed structure sensitivity in CO oxidation reaction. In

High surface area monodispersed Fe3O4 nanoparticles alone and on physical exfoliated graphite for improved supercapacitors

Science.gov (United States)

Sarno, Maria; Ponticorvo, Eleonora; Cirillo, Claudia

2016-12-01

Highly conductive, unsophisticated and easy to be obtained physical exfoliated graphite (PHG) supporting well dispersed magnetite, Fe3O4/PHG nanocomposite, has been prepared by a one-step chemical strategy and physico-chemical characterized. The nanocomposite, favoured by the a-polar nanoparticles (NPs) capping, results in a self-assembled monolayer of monodispersed Fe3O4, covering perfectly the hydrophobic surfaces of PHG. The nanocomposite as an electrode material was fabricated into a supercapacitor and characterized by cyclic voltammetry (CV) and galvanostatic charge-discharge measurements. It shows, after a suitable annealing, significant electrochemical properties (capacitance value of 787 F/g at 0.5 A g-1 and a Fe3O4/PHG weight ratio of 0.31) and good cycling stability (retention 91% after 30,000 cycles). Highly monodispersed very fine Fe3O4 NPs, covered by organic chains, have been also synthesized. The high surface area Fe3O4 NPs, after washing to leave a low content of organic chains able to avoid aggregation without excessively affecting the electrical properties of the material, exhibit remarkable pseudocapacitive activities, including the highest specific capacitance over reported for Fe3O4 (300 F/g at 0.5 A g-1).

Monodispersed MnO nanoparticles with epitaxial Mn{sub 3}O{sub 4} shells

Energy Technology Data Exchange (ETDEWEB)

Berkowitz, A E; Rodriguez, G F [Department of Physics, University of California, San Diego La Jolla, CA 92093 (United States); Hong, J I; Fullerton, E E [Center for Magnetic Recording Research, University of California-San Diego La Jolla, CA 92093 (United States); An, K; Hyeon, T [National Creative Research Initiative Center for Oxide Nanocrystalline Materials, Seoul National University, Seoul 151-744 (Korea, Republic of); Agarwal, N; Smith, D J [School of Materials and Department of Physics, Arizona State University, Tempe, AZ 85287 (United States)

2008-07-07

We report the microstructural and magnetic properties of monodispersed nanoparticles (NPs) of antiferromagnetic MnO (T{sub N} = 118 K), with epitaxial ferrimagnetic Mn{sub 3}O{sub 4} (T{sub C} = 43 K) shells. Above T{sub C}, an unusually large magnetization is present, produced by the uncompensated spins (UCSs) on the surface of the MnO particles. These spins impart a net anisotropy to the MnO particles that is approximately three orders of magnitude larger than the bulk value. As a result, an anomalously high blocking temperature is exhibited by the MnO particles, and finite coercivity and exchange bias are present above T{sub C}. When field cooled below T{sub C}, a strong exchange bias was established in the Mn{sub 3}O{sub 4} shells as a result of high net anisotropy of the MnO particles. A large coercivity was also observed. Models of several aspects of the behaviour of this unusual system emphasized the essential role of the UCSs on the surfaces of the MnO NPs.

Redox-Active Carbohydrate-Coated Nanoparticles: Self-Assembly of a Cyclodextrin-Polystyrene Glycopolymer with Tetrazine-Naphthalimide.

Science.gov (United States)

Gross, Andrew J; Haddad, Raoudha; Travelet, Christophe; Reynaud, Eric; Audebert, Pierre; Borsali, Redouane; Cosnier, Serge

2016-11-15

The controlled self-assembly of precise and well-defined photochemically and electrochemically active carbohydrate-coated nanoparticles offers the exciting prospect of biocompatible catalysts for energy storage/conversion and biolabeling applications. Here an aqueous nanoparticle system has been developed with a versatile outer layer for host-guest molecule encapsulation via β-cyclodextrin inclusion complexes. A β-cyclodextrin-modified polystyrene polymer was first obtained by copper nanopowder click chemistry. The glycopolymer enables self-assembly and controlled encapsulation of tetrazine-naphthalimide, as a model redox-active agent, into nanoparticles via nanoprecipitation. Cyclodextrin host-guest interactions permit encapsulation and internanoparticle cross-linking for the formation of fluorescent compound and clustered self-assemblies with chemically reversible electroactivity in aqueous solution. Light scattering experiments revealed stable particles with hydrodynamic diameters of 138 and 654 nm for nanoparticles prepared with tetrazine, of which 95% of the nanoparticles represent the smaller objects by number. Dynamic light scattering revealed differences as a function of preparation method in terms of size, 3-month stability, polydispersity, radius of gyration, and shape factor. Individual self-assemblies were visualized by atomic force microscopy and fluorescence microscopy and monitored in real-time by nanoparticle tracking analysis. UV-vis and fluorescence spectra provided insight into the optical properties and critical evidence for host-guest encapsulation as evidenced by solvachromatism and enhanced tetrazine uptake. Cyclic voltammetry was used to investigate the electrochemical properties and provided further support for encapsulation and an estimate of the tetrazine loading capacity in tandem with light scattering data.

Incorporation of Nanohybrid Films of Silica into Recycled Polystyrene Matrix

Directory of Open Access Journals (Sweden)

Genoveva Hernández-Padrón

2015-01-01

Full Text Available An alternative for the reutilization of polystyrene waste containers consisting in creating a hybrid material made of SiO2 nanoparticles embedded in a matrix of recycled polystyrene (PSR has been developed. Recycled polystyrene functionalized (PSRF was used to influence the morphological and antifog properties by the sol-gel synthesis of nanohybrid silica. To this end, silica nanoparticles were produced from alkoxide precursors in the presence of recycled polystyrene. The functionalization of this polymeric matrix was with the purpose of uniting in situ carboxyl and silanol groups during the sol-gel process. In this way, opaque or transparent solid substrates can be obtained, with each of these endowed with optical conditions that depend on the amount of reactants employed to prepare each nanohybrid specimen. The nanohybrids were labelled as SiO2/PSR (HPSR and SiO2/PSRF (HPSRF and their properties were then compared to those of commercial polystyrene (PS. All the prepared samples were used for coating glass substrates. The hydrophobicity of the resultant coatings was determined through contact angle measurement. The nanohybrid materials were characterized by FT-IR and 1H-NMR techniques. Additionally, TGA and SEM were employed to determine their thermal and textural properties.

Effects of surfactant and polymerization method on the synthesis of magnetic colloidal polymeric nanoparticles

International Nuclear Information System (INIS)

Puentes-Vara, Luis A.; Gregorio-Jauregui, Karla M.; Bolarín, Ana M.; Navarro-Clemente, Ma. E.; Dorantes, Héctor J.; Corea, Mónica

2016-01-01

The addition of superparamagnetic iron nanoparticles into polystyrene matrix allows for the modification of the physical properties as well as the implementation of new features in the hybrid nanomaterials. These materials have excellent potential for biomedical and bioengineering applications. Nevertheless, it is necessary to achieve a good dispersion of magnetic nanoparticles for its successful incorporation into polymer particles. This can be obtained through the use of a stabilizer, which provides stability against aggregation. In this work, magnetic nanoparticles were dispersed using different stabilizers. Subsequently, ferrofluids stabilized using the mixture of ABEX/IGEPAL and acrylic acid (AA) were used to synthesize PS-Fe 3 O 4 nanocomposites, through miniemulsion and emulsion polymerization conventional techniques. Semicontinuous and batch processes were compared, by varying surfactants and their concentrations. The PS-Fe 3 O 4 nanoparticles were characterized by dynamic light scattering, scanning electron microscopy, Raman spectroscopy, and vibrating sample magnetometer. Magnetic nanoparticle dispersions show better results when the anionic and nonionic surfactants are used as a mixture rather than when used alone. Results of DLS showed that the semicontinuous process allowed obtaining monodisperse materials, whereas polidisperse systems are generated in batch process. Raman spectroscopy confirmed the presence of magnetite and polystyrene in the nanocomposites. PS-Fe 3 O 4 nanoparticles showed superparamagnetic behavior with final magnetization of around 0.01 emu/g and low coercivity, properties that make them suitable for applications in wide fields of technology. Particle size (Dz), was lower than 300 nm in all cases. Moreover, the use of AA as stabilizer allows enhancing the PS-Fe 3 O 4 composite properties. These findings showed that particle size, morphology, and agglomeration are directly influenced by the concentration and the type of surfactant

Effects of surfactant and polymerization method on the synthesis of magnetic colloidal polymeric nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Puentes-Vara, Luis A.; Gregorio-Jauregui, Karla M. [Instituto Politécnico Nacional, ESIQIE, UPALM (Mexico); Bolarín, Ana M. [Universidad Autónoma Del Estado de Hidalgo (Mexico); Navarro-Clemente, Ma. E.; Dorantes, Héctor J.; Corea, Mónica, E-mail: mcoreat@yahoo.com.mx, E-mail: mcorea@ipn.mx [Instituto Politécnico Nacional, ESIQIE, UPALM (Mexico)

2016-07-15

The addition of superparamagnetic iron nanoparticles into polystyrene matrix allows for the modification of the physical properties as well as the implementation of new features in the hybrid nanomaterials. These materials have excellent potential for biomedical and bioengineering applications. Nevertheless, it is necessary to achieve a good dispersion of magnetic nanoparticles for its successful incorporation into polymer particles. This can be obtained through the use of a stabilizer, which provides stability against aggregation. In this work, magnetic nanoparticles were dispersed using different stabilizers. Subsequently, ferrofluids stabilized using the mixture of ABEX/IGEPAL and acrylic acid (AA) were used to synthesize PS-Fe{sub 3}O{sub 4} nanocomposites, through miniemulsion and emulsion polymerization conventional techniques. Semicontinuous and batch processes were compared, by varying surfactants and their concentrations. The PS-Fe{sub 3}O{sub 4} nanoparticles were characterized by dynamic light scattering, scanning electron microscopy, Raman spectroscopy, and vibrating sample magnetometer. Magnetic nanoparticle dispersions show better results when the anionic and nonionic surfactants are used as a mixture rather than when used alone. Results of DLS showed that the semicontinuous process allowed obtaining monodisperse materials, whereas polidisperse systems are generated in batch process. Raman spectroscopy confirmed the presence of magnetite and polystyrene in the nanocomposites. PS-Fe{sub 3}O{sub 4} nanoparticles showed superparamagnetic behavior with final magnetization of around 0.01 emu/g and low coercivity, properties that make them suitable for applications in wide fields of technology. Particle size (Dz), was lower than 300 nm in all cases. Moreover, the use of AA as stabilizer allows enhancing the PS-Fe{sub 3}O{sub 4} composite properties. These findings showed that particle size, morphology, and agglomeration are directly influenced by the

Activity of Antimicrobial Silver Polystyrene Nanocomposites

Directory of Open Access Journals (Sweden)

M. Palomba

2012-01-01

Full Text Available A simple technique based on doping polymers with in situ generated silver nanoparticles (Ag/PS films has been developed. In particular, an antiseptic material has been prepared by dissolving silver 1,5-cyclooctadiene-hexafluoroacetylacetonate in amorphous polystyrene, and the obtained solid solution has been heated for ca. 10 s at a convenient temperature (180°C. Under such conditions the metal precursor decomposes producing silver atoms that diffuse into the polymer and clusterize. The antimicrobial characteristics of the resulting polystyrene-based material have been accurately evaluated toward Escherichia coli (E. coli comparing the cytotoxicity effect of 10 wt.% and 30 wt.% (drastic and mild annealing silver-doped polystyrene to the corresponding pure micrometric silver powder. Two different bacterial viability assays were performed in order to demonstrate the cytotoxic effect of Ag/PS films on cultured E. coli: (1 turbidimetric determination of optical density; (2 BacLight fluorescence-based test. Both methods have shown that silver-doped polystyrene (30 wt.% provides higher antibacterial activity than pure Ag powder, under similar concentration and incubation conditions.

Amino-modified polystyrene nanoparticles affect signalling pathways of the sea urchin (Paracentrotus lividus) embryos.

Science.gov (United States)

Pinsino, Annalisa; Bergami, Elisa; Della Torre, Camilla; Vannuccini, Maria Luisa; Addis, Piero; Secci, Marco; Dawson, Kenneth A; Matranga, Valeria; Corsi, Ilaria

2017-03-01

Polystyrene nanoparticles have been shown to pose serious risk to marine organisms including sea urchin embryos based on their surface properties and consequently behaviour in natural sea water. The aim of this study is to investigate the toxicity pathways of amino polystyrene nanoparticles (PS-NH 2 , 50 nm) in Paracentrotus lividus embryos in terms of development and signalling at both protein and gene levels. Two sub-lethal concentrations of 3 and 4 μg/mL of PS-NH 2 were used to expose sea urchin embryos in natural sea water (PS-NH 2 as aggregates of 143 ± 5 nm). At 24 and 48 h post-fertilisation (hpf) embryonic development was monitored and variations in the levels of key proteins involved in stress response and development (Hsp70, Hsp60, MnSOD, Phospho-p38 Mapk) as well as the modulation of target genes (Pl-Hsp70, Pl-Hsp60, Pl-Cytochrome b, Pl-p38 Mapk, Pl-Caspase 8, Pl-Univin) were measured. At 48 hpf various striking teratogenic effects were observed such as the occurrence of cells/masses randomly distributed, severe skeletal defects and delayed development. At 24 hpf a significant up-regulation of Pl-Hsp70, Pl-p38 Mapk, Pl-Univin and Pl-Cas8 genes was found, while at 48 hpf only for Pl-Univin was observed. Protein profile showed different patterns as a significant increase of Hsp70 and Hsp60 only after 48 hpf compared to controls. Conversely, P-p38 Mapk protein significantly increased at 24 hpf and decreased at 48 hpf. Our findings highlight that PS-NH 2 are able to disrupt sea urchin embryos development by modulating protein and gene profile providing new understandings into the signalling pathways involved.

Monodisperse Magneto-Fluorescent Bifunctional Nanoprobes for Bioapplications

Science.gov (United States)

Zhang, Hongwang; Huang, Heng; Pralle, Arnd; Zeng, Hao

2013-03-01

We present the work on the synthesis of dye-doped monodisperse Fe/SiO2 core/shell nanoparticles as bifunctional probes for bioapplications. Magnetic nanoparticles (NP) have been widely studied as nano-probes for bio-imaging, sensing as well as for cancer therapy. Among all the NPs, Fe NPs have been the focus because they have very high magnetization. However, Fe NPs are usually not stable in ambient due to the fast surface oxidation of the NPs. On the other hand, dye molecules have long been used as probes for bio-imaging. But they are sensitive to environmental conditions. It requires passivation for both so that they can be stable for applications. In this work, monodisperse Fe NPs with sizes ranging from 13-20 nm have been synthesized through the chemical thermal-decomposition in a solution. Silica shells were then coated on the Fe NPs by a two-phase oil-in-water method. Dye molecules were first bonded to a silica precursor and then encapsulated into the silica shell during the coating process. The silica shells protect both the Fe NPs and dye molecules, which makes them as robust probes. The dye doped Fe/SiO2 core/shell NPs remain both highly magnetic and highly fluorescent. The stable dye doped Fe/SiO2NPs have been used as a dual functional probe for both magnetic heating and local nanoscale temperature sending, and their performance will be reported. Research supported by NSF DMR 0547036, DMR1104994.

Transient loading of CD34+ hematopoietic progenitor cells with polystyrene nanoparticles.

Science.gov (United States)

Deville, Sarah; Hadiwikarta, Wahyu Wijaya; Smisdom, Nick; Wathiong, Bart; Ameloot, Marcel; Nelissen, Inge; Hooyberghs, Jef

2017-01-01

CD34 + hematopoietic progenitor cells (HPCs) offer great opportunities to develop new treatments for numerous malignant and non-malignant diseases. Nanoparticle (NP)-based strategies can further enhance this potential, and therefore a thorough understanding of the loading behavior of HPCs towards NPs is essential for a successful application. The present study focusses on the interaction kinetics of 40 nm sized carboxylated polystyrene (PS) NPs with HPCs. Interestingly, a transient association of the NPs with HPCs is observed, reaching a maximum within 1 hour and declining afterwards. This behavior is not seen in dendritic cells (CD34-DCs) differentiated from HPCs, which display a monotonic increase in NP load. We demonstrate that this transient interaction requires an energy-dependent cellular process, suggesting active loading and release of NPs by HPCs. This novel observation offers a unique approach to transiently equip HPCs. A simple theoretical approach modeling the kinetics of NP loading and release is presented, contributing to a framework of describing this phenomenon.

Facile Synthesis of Monodisperse Gold Nanocrystals Using Virola oleifera

Science.gov (United States)

Milaneze, Bárbara A.; Oliveira, Jairo P.; Augusto, Ingrid; Keijok, Wanderson J.; Côrrea, Andressa S.; Ferreira, Débora M.; Nunes, Otalíbio C.; Gonçalves, Rita de Cássia R.; Kitagawa, Rodrigo R.; Celante, Vinícius G.; da Silva, André Romero; Pereira, Ana Claudia H.; Endringer, Denise C.; Schuenck, Ricardo P.; Guimarães, Marco C. C.

2016-10-01

The development of new routes and strategies for nanotechnology applications that only employ green synthesis has inspired investigators to devise natural systems. Among these systems, the synthesis of gold nanoparticles using plant extracts has been actively developed as an alternative, efficient, cost-effective, and environmentally safe method for producing nanoparticles, and this approach is also suitable for large-scale synthesis. This study reports reproducible and completely natural gold nanocrystals that were synthesized using Virola oleifera extract. V. oleifera resin is rich in epicatechin, ferulic acid, gallic acid, and flavonoids (i.e., quercetin and eriodictyol). These gold nanoparticles play three roles. First, these nanoparticles exhibit remarkable stability based on their zeta potential. Second, these nanoparticles are functionalized with flavonoids, and third, an efficient, economical, and environmentally friendly mechanism can be employed to produce green nanoparticles with organic compounds on the surface. Our model is capable of reducing the resin of V. oleifera, which creates stability and opens a new avenue for biological applications. This method does not require painstaking conditions or hazardous agents and is a rapid, efficient, and green approach for the fabrication of monodisperse gold nanoparticles.

Surface-enhanced Raman spectroscopy substrate based on Ag-coated self-assembled polystyrene spheres

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Mikac, Lara; Ivanda, Mile; Gotić, Marijan; Janicki, Vesna; Zorc, Hrvoje; Janči, Tibor; Vidaček, Sanja

2017-10-01

The silver (Ag) films were deposited on the monodispersed polystyrene spheres that were drop-coated on hydrophilic glass substrates in order to form a self-assembled 2D monolayer. Thus prepared Ag films over polystyrene nanospheres (AgFONs) were used to record the surface-enhanced Raman scattering (SERS) spectra of rhodamine 6G (R6G) and pyridine (λex = 514.5 nm). AgFONs were prepared by depositing 120, 180 and 240 nm thick Ag layer on the 1000 nm polystyrene spheres and 80, 120, 160 and 200 nm thick Ag layer on the 350 nm spheres as well as on their mixture (350 + 1000 nm). The silver was deposited by electron beam evaporation technique. The best enhancement of the Raman signal for both test molecules was obtained using 180 nm Ag film deposited on the 1000 nm spheres and using 80 nm Ag film deposited on the 350 nm polystyrene spheres. The lowest detectable concentrations of R6G and pyridine were 10-9 mol L-1 and 1.2 × 10-3 mol L-1, respectively. This study has shown that AgFONs could be regarded as good and reproducible SERS substrate for analytical detection of various organic molecules.

Synthesis of highly monodisperse particles composed of a magnetic core and fluorescent shell.

Science.gov (United States)

Nagao, Daisuke; Yokoyama, Mikio; Yamauchi, Noriko; Matsumoto, Hideki; Kobayashi, Yoshio; Konno, Mikio

2008-09-02

Highly monodisperse particles composed of a magnetic silica core and fluorescent polymer shell were synthesized with a combined technique of heterocoagulation and soap-free emulsion polymerization. Prior to heterocoagulation, monodisperse, submicrometer-sized silica particles were prepared with the Stober method, and magnetic nanoparticles were prepared with a modified Massart method in which a cationic silane coupling agent of N-trimethoxysilylpropyl- N, N, N-trimethylammonium chloride was added just after coprecipitation of Fe (2+) and Fe (3+). The silica particles with negative surface potential were heterocoagulated with the magnetic nanoparticles with positive surface potential. The magnetic silica particles obtained with the heterocoagulation were treated with sodium silicate to modify their surfaces with silica. In the formation of a fluorescent polymer shell onto the silica-coated magnetic silica cores, an amphoteric initiator of 2,2'-azobis[ N-(2-carboxyethyl)-2-2-methylpropionamidine] (VA-057) was used to control the colloidal stability of the magnetic cores during the polymer coating. The polymerization of St in the presence of a hydrophobic fluorophore of pyrene could coat the cores with fluorescent polymer shells, resulting in monodisperse particles with a magnetic silica core and fluorescent polymer shell. Measurements of zeta potential for the composite particles in different pH values indicated that the composite particles had an amphoteric property originating from VA-057 initiator.

Controlled synthesis and magnetic properties of monodispersed ceria nanoparticles

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Sumeet Kumar

2015-02-01

Full Text Available In the present study, monodispersed CeO2 nanoparticles (NPs of size 8.5 ± 1.0, 11.4 ± 1.0 and 15.4 ± 1.0 nm were synthesized using the sol-gel method. Size-dependent structural, optical and magnetic properties of as-prepared samples were investigated by X-ray diffraction (XRD, field emission scanning electron microscope (FE-SEM, high resolution transmission electron microscopy (HR-TEM, ultra-violet visible (UV-VIS spectroscopy, Raman spectroscopy and vibrating sample magnetometer (VSM measurements. The value of optical band gap is calculated for each particle size. The decrease in the value of optical band gap with increase of particle size may be attributed to the quantum confinement, which causes to produce localized states created by the oxygen vacancies due to the conversion of Ce4+ into Ce3+ at higher calcination temperature. The Raman spectra showed a peak at ∼461 cm-1 for the particle size 8.5 nm, which is attributed to the 1LO phonon mode. The shift in the Raman peak could be due to lattice strain developed due to variation in particle size. Weak ferromagnetism at room temperature is observed for each particle size. The values of saturation magnetization (Ms, coercivity (Hc and retentivity (Mr are increased with increase of particle size. The increase of Ms and Mr for larger particle size may be explained by increase of density of oxygen vacancies at higher calcination temperature. The latter causes high concentrations of Ce3+ ions activate more coupling between the individual magnetic moments of the Ce ions, leading to an increase of Ms value with the particle size. Moreover, the oxygen vacancies may also produce magnetic moment by polarizing spins of f electrons of cerium (Ce ions located around oxygen vacancies, which causes ferromagnetism in pure CeO2 samples.

Microwave absorption enhancement, magnetic coupling and ab initio electronic structure of monodispersed (Mn1-xCox)3O4 nanoparticles

Science.gov (United States)

Zhao, Pengfei; Liang, Chongyun; Gong, Xiwen; Gao, Ran; Liu, Jiwei; Wang, Min; Che, Renchao

2013-08-01

Monodispersed manganese oxide (Mn1-xCox)3O4 (0 nanoparticles, less than 10 nm size, are respectively synthesized via a facile thermolysis method at a rather low temperature, ranging from 90 to 100 °C, without any inertia gas for protection. The influences of the Co dopant content on the critical reaction temperature required for the nanoparticle formation, electronic band structures, magnetic properties, and the microwave absorption capability of (Mn1-xCox)3O4 are comprehensively investigated by means of both experimental and theoretical approaches including powder X-ray diffraction (XRD), electron energy loss spectroscopy (EELS), super conductivity quantum interference device (SQUID) examination, and first-principle simulations. Co is successfully doped into the Mn atomic sites of the (Mn1-xCox)3O4 lattice, which is further confirmed by EELS data acquired from one individual nanoparticle. Therefore, continuous solid solutions of well-crystallized (Mn1-xCox)3O4 products are achieved without any impurity phase or phase separation. With increases in the Co dopant concentration x from 0 to 0.5, the lattice parameters change systemically, where the overall saturation magnetization at 30 K increases due to the more intense coupling of the 3d electrons between Mn and Co, as revealed by simulations. The microwave absorption properties of the (Mn1-xCox)3O4 nanoparticles are examined between 2 and 18 GHz. The maximum absorption peak -11.0 dB of the x = 0 sample is enhanced to -11.5 dB for x = 0.2, -12.7 dB for x = 0.25, -15.6 dB for x = 0.33, and -24.0 dB for x = 0.5 respectively, suggesting the Co doping effects. Our results might provide novel insights into the understanding of the influences of metallic ion doping on the electromagnetic properties of metallic oxide nanomaterials.Monodispersed manganese oxide (Mn1-xCox)3O4 (0 nanoparticles, less than 10 nm size, are respectively synthesized via a facile thermolysis method at a rather low temperature, ranging from 90 to

Tuning the dielectric properties of polystyrene/poly(vinylidene fluoride) blends by selectively localizing carbon black nanoparticles.

Science.gov (United States)

Zhao, Xiaodong; Zhao, Jun; Cao, Jian-Ping; Wang, Xiaoyan; Chen, Min; Dang, Zhi-Min

2013-02-28

In this work, the dielectric properties of immiscible polystyrene (PS)/poly(vinylidene fluoride) (PVDF) blends are tuned by selectively localizing carbon black (CB) nanoparticles in different phases. The PS/PVDF blends have a wide window of cocontinuity (ca. 30-80 vol % in terms of the volume fraction of PS component (v(PS))). The selective localization of CB nanoparticles is achieved by using the masterbatch process during melt mixing. For the volume ratio PS/PVDF 1/1 and the volume fraction of CB nanoparticles (v(CB)) below but close to the percolation threshold (v(c)(CB)), the selective localization of CB nanoparticles in PVDF phase produces higher dielectric constant (ε) than that in PS phase, whereas the ε of the ternary mixtures without selective localization of fillers is in the middle. For the volume ratios PS/PVDF 1/2 and 2/1, the selective location of CB nanoparticles in different phases can be used to easily tune the system from conductive to insulating or inverse, which might have potential applications in industry. The fillers are found to be "fixed" in the masterbatch of PS or PVDF component and there is no migration of the fillers to another phase occurring during the further mixing process for the mixing time up to 30 min. Furthermore, the addition of CB nanoparticles to the polymer matrix is found to induce the brittle-ductile transition in the system and increase the compatibility between the immiscible PS and PVDF components, which should benefit the mechanical properties.

Synthesis and Magnetic Properties of Nearly Monodisperse CoFe2O4Nanoparticles Through a Simple Hydrothermal Condition

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Li Xing-Hua

2010-01-01

Full Text Available Abstract Nearly monodisperse cobalt ferrite (CoFe2O4 nanoparticles without any size-selection process have been prepared through an alluring method in an oleylamine/ethanol/water system. Well-defined nanospheres with an average size of 5.5 nm have been synthesized using metal chloride as the law materials and oleic amine as the capping agent, through a general liquid–solid-solution (LSS process. Magnetic measurement indicates that the particles exhibit a very high coercivity at 10 K and perform superparamagnetism at room temperature which is further illuminated by ZFC/FC curves. These superparamagnetic cobalt ferrite nanomaterials are considered to have potential application in the fields of biomedicine. The synthesis method is possible to be a general approach for the preparation of other pure binary and ternary compounds.

Self-charging of 198Au-labeled monodisperse gold aerosols studied with a miniature electrical mobility spectrometer

International Nuclear Information System (INIS)

Yeh, H.C.; Newton, G.J.; Raabe, O.G.; Boor, D.R.

1976-01-01

Knowledge of the electrostatic character of an aerosol may be essential in assessing its potential inhalation hazard. In inhalation studies with radioactive aerosols, the aerosol charge state may change in the course of transport due to the emission of α, β or γ radiations. This paper describes an experimental study of the self-charging of 198 Au-labeled aerosols of monodisperse gold spheres by β emission. A miniature aerosol electrical mobility spectrometer, suitable for use in inhalation studies with radioactive aerosols, was developed and used in this study. This device is relatively inexpensive, easy to manufacture and its contamination by radioactive material has been minimized. Using polystyrene latex spheres, ranging in diameter from 0.176 to 1.18 μm, the spectrometer was calibrated with flow rates ranging from 400 to 4800 ml/min. Experiments with two sizes of 198 Au-labeled monodisperse gold aerosols were performed. Results indicate that the radioactivity of an aerosol can cause self-charging and affect the charge distribution. (author)

Ferroferric oxide/polystyrene (Fe3O4/PS superparamagnetic nanocomposite via facile in situ bulk radical polymerization

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2010-03-01

Full Text Available Organo-modified ferroferric oxide superparamagnetic nanoparticles, synthesized by the coprecipitation of superparamagnetic nanoparticles in presence of oleic acid (OA, were incorporated in polystyrene (PS by the facile in situ bulk radical polymerization by using 2,2-azobisisobutyronitrile (AIBN as initiator. The transmission electron microscopy (TEM analysis of the resultant uniform ferroferric oxide/polystyrene superparamagnetic nanocomposite (Fe3O4/PS showed that the superparamagnetic nanoparticles had been dispersed homogeneously in the polymer matrix due to the surface grafted polystyrene, confirmed by Fourier transform infrared (FT-IR spectroscopy and thermogravimetric analysis (TGA. The superparamagnetic property of the Fe3O4/PS nanocomposite was testified by the vibrating sample magnetometer (VSM analysis. The strategy developed is expected to be applied for the large-scale industrial manufacturing of the superparamagnetic polymer nanocomposite.

Bioavailability and biodistribution of differently charged polystyrene nanoparticles upon oral exposure in rats

International Nuclear Information System (INIS)

Walczak, Agata P.; Hendriksen, Peter J. M.; Woutersen, Ruud A.; Zande, Meike van der; Undas, Anna K.; Helsdingen, Richard; Berg, Hans H. J. van den; Rietjens, Ivonne M. C. M.; Bouwmeester, Hans

2015-01-01

The likelihood of oral exposure to nanoparticles (NPs) is increasing, and it is necessary to evaluate the oral bioavailability of NPs. In vitro approaches could help reducing animal studies, but validation against in vivo studies is essential. Previously, we assessed the translocation of 50 nm polystyrene NPs of different charges (neutral, positive and negative) using a Caco-2/HT29-MTX in vitro intestinal translocation model. The NPs translocated in a surface charge-dependent manner. The present study aimed to validate this in vitro intestinal model by an in vivo study. For this, rats were orally exposed to a single dose of these polystyrene NPs and the uptake in organs was determined. A negatively charged NP was taken up more than other NPs, with the highest amounts in kidney (37.4 µg/g tissue), heart (52.8 µg/g tissue), stomach wall (98.3 µg/g tissue) and small intestinal wall (94.4 µg/g tissue). This partly confirms our in vitro findings, where the same NPs translocated to the highest extent. The estimated bioavailability of different types of NPs ranged from 0.2 to 1.7 % in vivo, which was much lower than in vitro (1.6–12.3 %). Therefore, the integrated in vitro model cannot be used for a direct prediction of the bioavailability of orally administered NPs. However, the model can be used for prioritizing NPs before further in vivo testing for risk assessment

Bioavailability and biodistribution of differently charged polystyrene nanoparticles upon oral exposure in rats

Energy Technology Data Exchange (ETDEWEB)

Walczak, Agata P. [Wageningen University, Division of Toxicology (Netherlands); Hendriksen, Peter J. M. [RIKILT Wageningen UR (Netherlands); Woutersen, Ruud A. [TNO Earth, Life and Social Sciences (Netherlands); Zande, Meike van der; Undas, Anna K.; Helsdingen, Richard [RIKILT Wageningen UR (Netherlands); Berg, Hans H. J. van den; Rietjens, Ivonne M. C. M. [Wageningen University, Division of Toxicology (Netherlands); Bouwmeester, Hans, E-mail: hans.bouwmeester@wur.nl [RIKILT Wageningen UR (Netherlands)

2015-05-15

The likelihood of oral exposure to nanoparticles (NPs) is increasing, and it is necessary to evaluate the oral bioavailability of NPs. In vitro approaches could help reducing animal studies, but validation against in vivo studies is essential. Previously, we assessed the translocation of 50 nm polystyrene NPs of different charges (neutral, positive and negative) using a Caco-2/HT29-MTX in vitro intestinal translocation model. The NPs translocated in a surface charge-dependent manner. The present study aimed to validate this in vitro intestinal model by an in vivo study. For this, rats were orally exposed to a single dose of these polystyrene NPs and the uptake in organs was determined. A negatively charged NP was taken up more than other NPs, with the highest amounts in kidney (37.4 µg/g tissue), heart (52.8 µg/g tissue), stomach wall (98.3 µg/g tissue) and small intestinal wall (94.4 µg/g tissue). This partly confirms our in vitro findings, where the same NPs translocated to the highest extent. The estimated bioavailability of different types of NPs ranged from 0.2 to 1.7 % in vivo, which was much lower than in vitro (1.6–12.3 %). Therefore, the integrated in vitro model cannot be used for a direct prediction of the bioavailability of orally administered NPs. However, the model can be used for prioritizing NPs before further in vivo testing for risk assessment.

Ordering of Polystyrene Nanoparticles on Substrates Pre-Coated with Different Polyelectrolyte Architectures

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Matthias Karg

2013-06-01

Full Text Available Adjusting the inter-particle distances in ordered nanoparticle arrays can create new nano-devices and is of increasing importance to a number of applications such as nanoelectronics and optical devices. The assembly of negatively charged polystyrene (PS nanoparticles (NPs on Poly(2-(dimethylaminoethyl methacrylate (PDMAEMA brushes, quaternized PDMAEMA brushes and Si/PEI/(PSS/PAH2, was studied using dip- and spin-coating techniques. By dip-coating, two dimensional (2-D, randomly distributed non-close packed particle arrays were assembled on Si/PEI/(PSS/PAH2 and PDMAEMA brushes. The inter-particle repulsion leads to lateral mobility of the particles on these surfaces. The 200 nm diameter PS NPs tended to an inter-particle distance of 350 to 400 nm (center to center. On quaternized PDMAEMA brushes, the strong attractive interaction between the NPs and the brush dominated, leading to clustering of the particles on the brush surface. Particle deposition using spin-coating at low spin rates resulted in hexagonal close-packed multilayer structures on Si/PEI/(PSS/PAH2. Close-packed assemblies with more pronounced defects are also observed on PDMAEMA brushes and QPDMAEMA brushes. In contrast, randomly distributed monolayer NP arrays were achieved at higher spin rates on all polyelectrolyte architectures. The area fraction of the particles decreased with increasing spin rate.

Transient loading of CD34+ hematopoietic progenitor cells with polystyrene nanoparticles

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Deville S

2017-01-01

Full Text Available Sarah Deville,1,2 Wahyu Wijaya Hadiwikarta,1 Nick Smisdom,1,2 Bart Wathiong,1,3 Marcel Ameloot,2 Inge Nelissen,1 Jef Hooyberghs1,3 1VITO, Flemish Institute for Technological Research, Mol, Belgium; 2Biomedical Research Institute, Hasselt University, Diepenbeek, Belgium; 3Theoretical Physics, Hasselt University, Diepenbeek, Belgium Abstract: CD34+ hematopoietic progenitor cells (HPCs offer great opportunities to develop new treatments for numerous malignant and non-malignant diseases. Nanoparticle (NP-based strategies can further enhance this potential, and therefore a thorough understanding of the loading behavior of HPCs towards NPs is essential for a successful application. The present study focusses on the interaction kinetics of 40 nm sized carboxylated polystyrene (PS NPs with HPCs. Interestingly, a transient association of the NPs with HPCs is observed, reaching a maximum within 1 hour and declining afterwards. This behavior is not seen in dendritic cells (CD34-DCs differentiated from HPCs, which display a monotonic increase in NP load. We demonstrate that this transient interaction requires an energy-dependent cellular process, suggesting active loading and release of NPs by HPCs. This novel observation offers a unique approach to transiently equip HPCs. A simple theoretical approach modeling the kinetics of NP loading and release is presented, contributing to a framework of describing this phenomenon. Keywords: nanoparticles, hematopoietic progenitor cells, dendritic cells, uptake, release

Magnetic properties of iron-oxide and (iron, cobalt)-oxide nanoparticles synthesized in polystyrene resin matrix

International Nuclear Information System (INIS)

Naik, R.; Kroll, E.; Rodak, D.; Tsoi, G.M.; McCullen, E.; Wenger, L.E.; Suryanarayanan, R.; Naik, V.M.; Vaishnava, P.P.; Tao, Qu; Boolchand, P.

2004-01-01

A sulfonated polystyrene resin matrix was ion exchanged with aqueous solutions of (1) FeCl 2 , (2) FeCl 3 , (3) 2FeCl 2 :FeCl 3 , (4) 9FeCl 2 :CoCl 2 , and (5) 4FeCl 2 :CoCl 2 to prepare magnetic nanoparticles of varying size. The samples were characterized by X-ray diffraction (XRD), 57 Fe Mossbauer spectroscopy, X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM), and identify two major phases: γ-Fe 2 O 3 , CoFe 2 O 4 , and perhaps a minor Fe 3 O 4 phase. SQUID magnetometry measurements indicate superparamagnetic particles with blocking temperatures (T B ) ranging from 20 K to room temperature

Magnetic properties of iron-oxide and (iron, cobalt)-oxide nanoparticles synthesized in polystyrene resin matrix

Science.gov (United States)

Naik, R.; Kroll, E.; Rodak, D.; Tsoi, G. M.; McCullen, E.; Wenger, L. E.; Suryanarayanan, R.; Naik, V. M.; Vaishnava, P. P.; Tao, Qu; Boolchand, P.

2004-05-01

A sulfonated polystyrene resin matrix was ion exchanged with aqueous solutions of (1) FeCl2, (2) FeCl3, (3) 2FeCl2:FeCl3, (4) 9FeCl2:CoCl2, and (5) 4FeCl2:CoCl2 to prepare magnetic nanoparticles of varying size. The samples were characterized by X-ray diffraction (XRD), 57Fe Mossbauer spectroscopy, X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM), and identify two major phases: γ-Fe2O3, CoFe2O4, and perhaps a minor Fe3O4 phase. SQUID magnetometry measurements indicate superparamagnetic particles with blocking temperatures (TB) ranging from 20K to room temperature.

A generalized diffusion model for growth of nanoparticles synthesized by colloidal methods.

Science.gov (United States)

Wen, Tianlong; Brush, Lucien N; Krishnan, Kannan M

2014-04-01

A nanoparticle growth model is developed to predict and guide the syntheses of monodisperse colloidal nanoparticles in the liquid phase. The model, without any a priori assumptions, is based on the Fick's law of diffusion, conservation of mass and the Gibbs-Thomson equation for crystal growth. In the limiting case, this model reduces to the same expression as the currently accepted model that requires the assumption of a diffusion layer around each nanoparticle. The present growth model bridges the two limiting cases of the previous model i.e. complete diffusion controlled and adsorption controlled growth of nanoparticles. Specifically, the results show that a monodispersion of nanoparticles can be obtained both with fast monomer diffusion and with surface reaction under conditions of small diffusivity to surface reaction constant ratio that results is growth 'focusing'. This comprehensive description of nanoparticle growth provides new insights and establishes the required conditions for fabricating monodisperse nanoparticles critical for a wide range of applications. Copyright © 2013 Elsevier Inc. All rights reserved.

Toward transparent nanocomposites based on polystyrene matrix and PMMA-grafted CeO2 nanoparticles.

Science.gov (United States)

Parlak, Onur; Demir, Mustafa M

2011-11-01

The association of transparent polymer and nanosized pigment particles offers attractive optical materials for various potential and existing applications. However, the particles embedded into polymers scatter light due to refractive index (RI) mismatch and reduce transparency of the resulting composite material. In this study, optical composites based on polystyrene (PS) matrix and poly(methyl methacrylate) (PMMA)-grafted CeO(2) hybrid particles were prepared. CeO(2) nanoparticles with an average diameter of 18 ± 8 nm were precipitated by treating Ce(NO(3))·6H(2)O with urea in the presence of a polymerizable surfactant, 3-methacyloxypropyltrimethoxy silane. PMMA chains were grafted on the surface of the nanoparticles upon free radical in situ solution polymerization. While blending of unmodified CeO(2) particles with PS resulted in opaque films, the transparency of the composite films was remarkably enhanced when prepared by PMMA-grafted CeO(2) hybrid particles, particularly those having a PMMA thickness of 9 nm. The improvement in transparency is presumably due to the reduction in RI mismatch between CeO(2) particles and the PS matrix when using PMMA chains at the interface.

Atomistic simulation of the coupled adsorption and unfolding of protein GB1 on the polystyrenes nanoparticle surface

Science.gov (United States)

Xiao, HuiFang; Huang, Bin; Yao, Ge; Kang, WenBin; Gong, Sheng; Pan, Hai; Cao, Yi; Wang, Jun; Zhang, Jian; Wang, Wei

2018-03-01

Understanding the processes of protein adsorption/desorption on nanoparticles' surfaces is important for the development of new nanotechnology involving biomaterials; however, an atomistic resolution picture for these processes and for the simultaneous protein conformational change is missing. Here, we report the adsorption of protein GB1 on a polystyrene nanoparticle surface using atomistic molecular dynamic simulations. Enabled by metadynamics, we explored the relevant phase space and identified three protein states, each involving both the adsorbed and desorbed modes. We also studied the change of the secondary and tertiary structures of GB1 during adsorption and the dominant interactions between the protein and surface in different adsorption stages. The results we obtained from simulation were found to be more adequate and complete than the previous one. We believe the model presented in this paper, in comparison with the previous ones, is a better theoretical model to understand and explain the experimental results.

Secreted protein eco-corona mediates uptake and impacts of polystyrene nanoparticles on Daphnia magna.

Science.gov (United States)

Nasser, Fatima; Lynch, Iseult

2016-03-30

Nanoparticles (NPs) are defined as having at least one external dimension between 1 and 100 nm. Due to their small size, NPs have a large surface area to volume ratio giving them unique characteristics that differ from bulk material of the same chemical composition. As a result these novel materials have found numerous applications in medical and industrial fields with the result that environmental exposure to NPs is increasingly likely. Similarly, increased reliance on plastic, which degrades extremely slowly in the environment, is resulting in increased accumulation of micro-/nano-plastics in fresh and marine waters, whose ecotoxicological impacts are as yet poorly understood. Although NPs are well known to adsorb macromolecules from their environment, forming a biomolecule corona which changes the NP identity and how it interacts with organisms, significantly less research has been performed on the ecological corona (eco-corona). Secretion of biomolecules is a well established predator-prey response in aquatic food chains, raising the question of whether NPs interact with secreted proteins, and the impact of such interaction on NP uptake and ecotoxicity. We report here initial studies, including optimisation of protocols using carboxylic-acid and amino modified spherical polystyrene NPs, to assess interaction of NPs with biomolecules secreted by Daphnia magna and the impact of these interactions on NP uptake, retention and toxicity towards Daphnia magna. Daphnia magna are an important environmental indicator species who may be especially sensitive to nanoparticles (NPs) as a result of being filter-feeders. This paper demonstrates for the first time that proteins released by Daphnia magna create an eco-corona around polystyrene NPs which causes heightened uptake of the NPs and consequently increases toxicity. The secreted protein eco-corona also causes the NPs to be less efficiently removed from the gut of D. magna and NPs remaining in the gut of D. magna

Preparation and thermal properties of polystyrene/silica nanocomposites

Czech Academy of Sciences Publication Activity Database

Bera, O.; Pilić, B.; Pavličević, J.; Jovičić, M.; Holló, B.; Meszaros Szecsenyi, K.; Špírková, Milena

2011-01-01

Roč. 515, č. 1/2 (2011), s. 1-5 ISSN 0040-6031 R&D Projects: GA AV ČR(CZ) IAAX08240901 Institutional research plan: CEZ:AV0Z40500505 Keywords : polystyrene * silica nanoparticles * nanocomposites Subject RIV: JI - Composite Materials Impact factor: 1.805, year: 2011

Green Synthesis, Characterization, and Antibacterial Activity of Silver/Polystyrene Nanocomposite

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Manal A. Awad

2015-01-01

Full Text Available A novel, nontoxic, simple, cost-effective and ecofriendly technique was used to synthesize green silver nanoparticles (AgNPs. The AgNPs were synthesized using orange peel extract as a reducing agent for silver nitrate salt (AgNO3. The particle size distribution of AgNPs was determined by Dynamic Light Scattering (DLS. The average size of silver nanoparticles was 98.43 nm. The stable dispersion of silver nanoparticles was added slowly to polystyrene solution in toluene maintaining the temperature at 70°C. The AgNPs/polystyrene (PS nanocomposite solution was cast in a petri dish. The silver nanoparticles encapsulated within polymer chains were characterized by X-ray diffraction (XRD and Scanning Electron Microscopy (SEM equipped with Energy Dispersive Spectroscopy (EDS in addition to Transmission Electron Microscopy (TEM. The green AgNPs/PS nanocomposite film exhibited antimicrobial activity against Gram-negative bacteria Escherichia coli, Klebsiella pneumoniae and Salmonella, and Gram-positive bacteria Staphylococcus aureus. Thus, the key findings of the work include the use of a safe and simple AgNPs/PS nanocomposite which had a marked antibacterial activity which has a potential application in food packaging.

Facile approach in fabricating superhydrophobic ZnO/polystyrene nanocomposite coating

Science.gov (United States)

Qing, Yongquan; Zheng, Yansheng; Hu, Chuanbo; Wang, Yong; He, Yi; Gong, Yong; Mo, Qian

2013-11-01

In this paper, we report a simple and inexpensive method for fabricating modified-ZnO/polystyrene superhydrophobic surface on the cotton textiles. The surface wettability and topology of coating were characterized by contact angle measurement, Scanning electron microscope and Fourier transform infrared spectrometry. The results showed that the hydrophobic CH3 and CF2 group was introduced into ZnO particles via modification, the ZnO nanoparticles were modified from hydrophilic to hydrophobic. When the weight ratio of modified-ZnO to polystyrene was 7:3, the ZnO/polystyrene composite coating contact angle was 158°, coating surface with hierarchical micro/nano structures. Furthermore, the superhydrophobic cotton texiles have a very extensive application prospect in water-oil separation.

Comparative Study of Antibacterial Properties of Polystyrene Films with TiOx and Cu Nanoparticles Fabricated using Cluster Beam Technique

DEFF Research Database (Denmark)

Popok, Vladimir; Jeppesen, Cesarino; Fojan, Peter

2018-01-01

Background: Antibacterial materials are of high importance for medicine, food production and conservation. Among these materials, polymer films with metals nanoparticles (NPs) are of considerable attention for many practical applications. Results: The paper describes a novel approach...... for the formation of bactericidal media which are represented by thin polymer films (polystyrene in the current case), produced by spin-coating, with Ti and Cu NPs deposited from cluster beams. Ti NPs are treated in three different ways in order to study different approaches for oxidation and, thus, efficiency...

Improved polymer thin-film wetting behavior through nanoparticle segregation to interfaces

International Nuclear Information System (INIS)

Krishnan, R S; Mackay, M E; Duxbury, P M; Hawker, C J; Asokan, Suba; Wong, Michael S; Goyette, Rick; Thiyagarajan, P

2007-01-01

We report a systematic study of improved wetting behavior for thin polymer films containing nanoparticles, as a function of nanoparticle size and concentration, the energy of the substrate and the dielectric properties of the nanoparticles. An enthalpy matched system consisting of polystyrene nanoparticles in linear polystyrene is used to show that nanoparticles are uniformly distributed in the film after spin coating and drying. However, on annealing the film above its bulk glass transition temperature these nanoparticles segregate strongly to the solid substrate. We find that for a wide range of film thicknesses and nanoparticle sizes, a substrate coverage of nanoparticles of approximately a monolayer is required for dewetting inhibition. Cadmium selenide quantum dots also inhibit dewetting of polystyrene thin films, again when a monolayer is present. Moreover, TEM microscopy images indicate that CdSe quantum dots segregate primarily to the air interface. Theoretical interpretation of these phenomena suggests that gain of linear chain configurational entropy promotes segregation of nanoparticles to the solid substrate, as occurs for polystyrene nanoparticles; however, for CdSe nanoparticles this is offset by surface energy or enthalpic terms which promote segregation of the nanoparticles to the air interface

Aqueous dispersion of monodisperse magnetic iron oxide nanocrystals through phase transfer

International Nuclear Information System (INIS)

Yu, William W; Chang, Emmanuel; Sayes, Christie M; Drezek, Rebekah; Colvin, Vicki L

2006-01-01

A facile method was developed for completely transferring high quality monodisperse iron oxide nanocrystals from organic solvents to water. The as-prepared aqueous dispersions of iron oxide nanocrystals were extremely stable and could be functionalized for bioconjugation with biomolecules. These iron oxide nanocrystals showed negligible cytotoxicity to human breast cancer cells (SK-BR-3) and human dermal fibroblast cells. This method is general and versatile for many organic solvent-synthesized nanoparticles, including fluorescent semiconductor nanocrystals

Uniform formation of Au coated polystyrene core-shell structure using metallization process

Energy Technology Data Exchange (ETDEWEB)

Kim, Kyoungseob; Koo, Jonghyun; Roh, Yonghan, E-mail: yhroh@skku.edu

2011-08-01

There are several methods for the fabrication of core-shell particles, including chemical reduction and self-assembly. In this study, the chemical reduction method was used to fabricate 100 nm, Au-coated polystyrene nanoparticles. The formation of the gold layer was based on the increase of gold coverage by the reaction with aniline and HAuCl{sub 4}. This method allowed for efficient control of the gold coverage and led to relatively stable products. The formation of Au clusters on the surface of the 100 nm polystyrene beads was characterized by scanning electron microscope and high resolution tunneling electron microscope. As a result, the Au-coated nanoparticles can be used in various applications such as surface plasmon resonators, drug delivery systems and electronic optical devices.

Size-Dependent Regulation of Intracellular Trafficking of Polystyrene Nanoparticle-Based Drug-Delivery Systems.

Science.gov (United States)

Wang, Ting; Wang, Lu; Li, Xiaoming; Hu, Xingjie; Han, Yuping; Luo, Yao; Wang, Zejun; Li, Qian; Aldalbahi, Ali; Wang, Lihua; Song, Shiping; Fan, Chunhai; Zhao, Yun; Wang, Maolin; Chen, Nan

2017-06-07

Nanoparticles (NPs) have shown great promise as intracellular imaging probes or nanocarriers and are increasingly being used in biomedical applications. A detailed understanding of how NPs get "in and out" of cells is important for developing new nanomaterials with improved selectivity and less cytotoxicity. Both physical and chemical characteristics have been proven to regulate the cellular uptake of NPs. However, the exocytosis process and its regulation are less explored. Herein, we investigated the size-regulated endocytosis and exocytosis of carboxylated polystyrene (PS) NPs. PS NPs with a smaller size were endocytosed mainly through the clathrin-dependent pathway, whereas PS NPs with a larger size preferred caveolae-mediated endocytosis. Furthermore, our results revealed exocytosis of larger PS NPs and tracked the dynamic process at the single-particle level. These results indicate that particle size is a key factor for the regulation of intracellular trafficking of NPs and provide new insight into the development of more effective cellular nanocarriers.

Nanoparticles and their tailoring with laser light

International Nuclear Information System (INIS)

Hubenthal, Frank

2009-01-01

Monodisperse noble metal nanoparticles are of tremendous interest for numerous applications, such as surface-enhanced Raman spectroscopy, catalysis or biosensing. However, preparation of monodisperse metal nanoparticles is still a challenging task, because typical preparation methods yield nanoparticle ensembles with broad shape and/or size distributions. To overcome this drawback, tailoring of metal nanoparticles with laser light has been developed, which is based on the pronounced shape- and size-dependent optical properties of metal nanoparticles. I will demonstrate that nanoparticle tailoring with ns-pulsed laser light is a suitable method to prepare nanoparticle ensembles with a narrow shape and/or size distribution. While irradiation with ns-pulsed laser light during nanoparticle growth permits a precise shape tailoring, post-grown irradiation allows a size tailoring. For example, the initial broad Gaussian size distribution of silver nanoparticles on quartz substrates with a standard deviation of σ= 30% is significantly reduced to as little as σ= 10% after tailoring. This paper addresses teachers of undergraduate and advanced school level as well as students. It assumes some fundamental knowledge in solid-state physics, thermodynamics and resonance vibration.

Magnetic properties of iron-oxide and (iron, cobalt)-oxide nanoparticles synthesized in polystyrene resin matrix

Energy Technology Data Exchange (ETDEWEB)

Naik, R. E-mail: naik@physics.wayne.edu; Kroll, E.; Rodak, D.; Tsoi, G.M.; McCullen, E.; Wenger, L.E.; Suryanarayanan, R.; Naik, V.M.; Vaishnava, P.P.; Tao, Qu; Boolchand, P

2004-05-01

A sulfonated polystyrene resin matrix was ion exchanged with aqueous solutions of (1) FeCl{sub 2}, (2) FeCl{sub 3}, (3) 2FeCl{sub 2}:FeCl{sub 3}, (4) 9FeCl{sub 2}:CoCl{sub 2}, and (5) 4FeCl{sub 2}:CoCl{sub 2} to prepare magnetic nanoparticles of varying size. The samples were characterized by X-ray diffraction (XRD), {sup 57}Fe Mossbauer spectroscopy, X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM), and identify two major phases: {gamma}-Fe{sub 2}O{sub 3}, CoFe{sub 2}O{sub 4}, and perhaps a minor Fe{sub 3}O{sub 4} phase. SQUID magnetometry measurements indicate superparamagnetic particles with blocking temperatures (T{sub B}) ranging from 20 K to room temperature.

Microporous polystyrene particles for selective carbon dioxide capture.

Science.gov (United States)

Kaliva, Maria; Armatas, Gerasimos S; Vamvakaki, Maria

2012-02-07

This study presents the synthesis of microporous polystyrene particles and the potential use of these materials in CO(2) capture for biogas purification. Highly cross-linked polystyrene particles are synthesized by the emulsion copolymerization of styrene (St) and divinylbenzene (DVB) in water. The cross-link density of the polymer is varied by altering the St/DVB molar ratio. The size and the morphology of the particles are characterized by scanning and transmission electron microscopy. Following supercritical point drying with carbon dioxide or lyophilization from benzene, the polystyrene nanoparticles exhibit a significant surface area and permanent microporosity. The dried particles comprising 35 mol % St and 65 mol % DVB possess the largest surface area, ∼205 m(2)/g measured by Brunauer-Emmett-Teller and ∼185 m(2)/g measured by the Dubinin-Radushkevich method, and a total pore volume of 1.10 cm(3)/g. Low pressure measurements suggest that the microporous polystyrene particles exhibit a good separation performance of CO(2) over CH(4), with separation factors in the range of ∼7-13 (268 K, CO(2)/CH(4) = 5/95 gas mixture), which renders them attractive candidates for use in gas separation processes.

Silica-Polystyrene Nanocomposite Particles Synthesized by Nitroxide-Mediated Polymerization and Their Encapsulation through Miniemulsion Polymerization

Directory of Open Access Journals (Sweden)

Bérangère Bailly

2006-01-01

Full Text Available Polystyrene (PS chains with molecular weights comprised between 8000 and 64000 g⋅mol-1 and narrow polydispersities were grown from the surface of silica nanoparticles (Aerosil A200 fumed silica and Stöber silica, resp. through nitroxide-mediated polymerization (NMP. Alkoxyamine initiators based on N-tert-butyl-1-diethylphosphono-2,2-dimethylpropyl nitroxide (DEPN and carrying a terminal functional group have been synthesized in situ and grafted to the silica surface. The resulting grafted alkoxyamines have been employed to initiate the growth of polystyrene chains from the inorganic surface. The maximum grafting density of the surface-tethered PS chains was estimated and seemed to be limited by initiator confinement at the interface. Then, the PS-grafted Stöber silica nanoparticles were entrapped inside latex particles via miniemulsion polymerization. Transmission electron microscopy indicated the successful formation of silica-polystyrene core-shell particles.

Surface charge-specific interactions between polymer nanoparticles and ABC transporters in Caco-2 cells

Energy Technology Data Exchange (ETDEWEB)

Bhattacharjee, Sourav, E-mail: sourav.bhattacharjee@wur.nl [Wageningen University, Laboratory of Organic Chemistry (Netherlands); Opstal, Edward J. van; Alink, Gerrit M. [Wageningen University, Division of Toxicology (Netherlands); Marcelis, Antonius T. M.; Zuilhof, Han [Wageningen University, Laboratory of Organic Chemistry (Netherlands); Rietjens, Ivonne M. C. M. [Wageningen University, Division of Toxicology (Netherlands)

2013-06-15

The surface charge-dependent transport of polymeric nanoparticles (PNPs) across Caco-2 monolayers grown on transwell culture systems as an in vitro model for intestinal transport was tested. The transport of well-characterized, monodisperse, and fluorescent tri-block copolymer nanoparticles (TCNPs/size {approx}45 nm) and polystyrene nanoparticles (PSNPs/size {approx}50 nm), with different surface charges (positive and negative), was quantified. The positive PNPs showed a higher intracellular uptake and flux across the Caco-2 monolayers than the negative PNPs. Multidrug resistance/P-glycoprotein (MDR1/P-gp), a specific ATP-binding cassette (ABC) transporter, was found to play a major role in the cellular efflux of positive PNPs, whereas the multidrug resistance protein 1 took part in the efflux of negative PNPs from Caco-2 cells. The positive PNPs also caused an increased cellular uptake and apical to basolateral transport of the carcinogen PhIP across the Caco-2 monolayer. The flavonoid quercetin, which is known to interact with ABC transporters, promoted the intracellular uptake of different PNPs and interfered with the normal distribution patterns of PNPs in the transwell system. These results indicate that PNPs display surface charge-specific interactions with ABC transporters and can even affect the bioavailability of toxic food-borne compounds (like pro-carcinogens).

Surface charge-specific interactions between polymer nanoparticles and ABC transporters in Caco-2 cells

Science.gov (United States)

Bhattacharjee, Sourav; van Opstal, Edward J.; Alink, Gerrit M.; Marcelis, Antonius T. M.; Zuilhof, Han; Rietjens, Ivonne M. C. M.

2013-06-01

The surface charge-dependent transport of polymeric nanoparticles (PNPs) across Caco-2 monolayers grown on transwell culture systems as an in vitro model for intestinal transport was tested. The transport of well-characterized, monodisperse, and fluorescent tri-block copolymer nanoparticles (TCNPs/size 45 nm) and polystyrene nanoparticles (PSNPs/size 50 nm), with different surface charges (positive and negative), was quantified. The positive PNPs showed a higher intracellular uptake and flux across the Caco-2 monolayers than the negative PNPs. Multidrug resistance/P-glycoprotein (MDR1/P-gp), a specific ATP-binding cassette (ABC) transporter, was found to play a major role in the cellular efflux of positive PNPs, whereas the multidrug resistance protein 1 took part in the efflux of negative PNPs from Caco-2 cells. The positive PNPs also caused an increased cellular uptake and apical to basolateral transport of the carcinogen PhIP across the Caco-2 monolayer. The flavonoid quercetin, which is known to interact with ABC transporters, promoted the intracellular uptake of different PNPs and interfered with the normal distribution patterns of PNPs in the transwell system. These results indicate that PNPs display surface charge-specific interactions with ABC transporters and can even affect the bioavailability of toxic food-borne compounds (like pro-carcinogens).

Surface charge-specific interactions between polymer nanoparticles and ABC transporters in Caco-2 cells

International Nuclear Information System (INIS)

Bhattacharjee, Sourav; Opstal, Edward J. van; Alink, Gerrit M.; Marcelis, Antonius T. M.; Zuilhof, Han; Rietjens, Ivonne M. C. M.

2013-01-01

The surface charge-dependent transport of polymeric nanoparticles (PNPs) across Caco-2 monolayers grown on transwell culture systems as an in vitro model for intestinal transport was tested. The transport of well-characterized, monodisperse, and fluorescent tri-block copolymer nanoparticles (TCNPs/size ∼45 nm) and polystyrene nanoparticles (PSNPs/size ∼50 nm), with different surface charges (positive and negative), was quantified. The positive PNPs showed a higher intracellular uptake and flux across the Caco-2 monolayers than the negative PNPs. Multidrug resistance/P-glycoprotein (MDR1/P-gp), a specific ATP-binding cassette (ABC) transporter, was found to play a major role in the cellular efflux of positive PNPs, whereas the multidrug resistance protein 1 took part in the efflux of negative PNPs from Caco-2 cells. The positive PNPs also caused an increased cellular uptake and apical to basolateral transport of the carcinogen PhIP across the Caco-2 monolayer. The flavonoid quercetin, which is known to interact with ABC transporters, promoted the intracellular uptake of different PNPs and interfered with the normal distribution patterns of PNPs in the transwell system. These results indicate that PNPs display surface charge-specific interactions with ABC transporters and can even affect the bioavailability of toxic food-borne compounds (like pro-carcinogens).

Monodispersed Carbon-Coated Cubic NiP2 Nanoparticles Anchored on Carbon Nanotubes as Ultra-Long-Life Anodes for Reversible Lithium Storage.

Science.gov (United States)

Lou, Peili; Cui, Zhonghui; Jia, Zhiqing; Sun, Jiyang; Tan, Yingbin; Guo, Xiangxin

2017-04-25

In search of new electrode materials for lithium-ion batteries, metal phosphides that exhibit desirable properties such as high theoretical capacity, moderate discharge plateau, and relatively low polarization recently have attracted a great deal of attention as anode materials. However, the large volume changes and thus resulting collapse of electrode structure during long-term cycling are still challenges for metal-phosphide-based anodes. Here we report an electrode design strategy to solve these problems. The key to this strategy is to confine the electroactive nanoparticles into flexible conductive hosts (like carbon materials) and meanwhile maintain a monodispersed nature of the electroactive particles within the hosts. Monodispersed carbon-coated cubic NiP 2 nanoparticles anchored on carbon nanotubes (NiP 2 @C-CNTs) as a proof-of-concept were designed and synthesized. Excellent cyclability (more than 1000 cycles) and capacity retention (high capacities of 816 mAh g -1 after 1200 cycles at 1300 mA g -1 and 654.5 mAh g -1 after 1500 cycles at 5000 mA g -1 ) are characterized, which is among the best performance of the NiP 2 anodes and even most of the phosphide-based anodes reported so far. The impressive performance is attributed to the superior structure stability and the enhanced reaction kinetics incurred by our design. Furthermore, a full cell consisting of a NiP 2 @C-CNTs anode and a LiFePO 4 cathode is investigated. It delivers an average discharge capacity of 827 mAh g -1 based on the mass of the NiP 2 anode and exhibits a capacity retention of 80.7% over 200 cycles, with an average output of ∼2.32 V. As a proof-of-concept, these results demonstrate the effectiveness of our strategy on improving the electrode performance. We believe that this strategy for construction of high-performance anodes can be extended to other phase-transformation-type materials, which suffer a large volume change upon lithium insertion/extraction.

Plasma-assisted synthesis of monodispersed and robust Ruthenium ultrafine nanocatalysts for organosilane oxidation and oxygen evolution reactions

NARCIS (Netherlands)

Gnanakumar, E.S.; Ng, W.; Filiz, B.C.; Rothenberg, G.; Wang, S.; Xu, H.; Pastor-Pérez, L.; Pastor-Blas, M.M.; Sepúlveda-Escribano, A.; Yan, N.; Shiju, N.R.

2017-01-01

We report a facile and general approach for preparing ultrafine ruthenium nanocatalysts by using a plasma-assisted synthesis at <100 °C. The resulting Ru nanoparticles are monodispersed (typical size 2 nm) and remain that way upon loading onto carbon and TiO2 supports. This gives robust catalysts

Nanostructural and magnetic studies of virtually monodispersed NiFe2O4 nanocrystals synthesized by a liquid–solid-solution assisted hydrothermal route

International Nuclear Information System (INIS)

Li Xinghua; Tan Guoguo; Chen Wei; Zhou Baofan; Xue Desheng; Peng Yong; Li, Fashen; Mellors, Nigel J.

2012-01-01

This study presents a comprehensively and systematically structural, chemical and magnetic characterization of ∼9.5 nm virtually monodispersed nickel ferrite (NiFe 2 O 4 ) nanoparticles prepared using a modified liquid–solid-solution (LSS) assisted hydrothermal method. Lattice-resolution scanning transmission electron microscope (STEM) and converged beam electron diffraction pattern (CBED) techniques are adapted to characterize the detailed spatial morphology and crystal structure of individual NiFe 2 O 4 particles at nano scale for the first time. It is found that each NiFe 2 O 4 nanoparticle is single crystal with an fcc structure. The morphology investigation reveals that the prepared NiFe 2 O 4 nanoparticles of which the surfaces are decorated by oleic acid are dispersed individually in hexane. The chemical composition of nickel ferrite nanoparticles is measured to be 1:2 atomic ratio of Ni:Fe, indicating a pure NiFe 2 O 4 composition. Magnetic measurements reveal that the as-synthesized nanocrystals displayed superparamagnetic behavior at room temperature and were ferromagnetic at 10 K. The nanoscale characterization and magnetic investigation of monodispersed NiFe 2 O 4 nanoparticles should be significant for its potential applications in the field of biomedicine and magnetic fluid using them as magnetic materials.

Microwave Synthesized Monodisperse CdS Spheres of Different Size and Color for Solar Cell Applications

Directory of Open Access Journals (Sweden)

Carlos A. Rodríguez-Castañeda

2015-01-01

Full Text Available Monodisperse CdS spheres of size of 40 to 140 nm were obtained by microwave heating from basic solutions. It is observed that larger CdS spheres were formed at lower solution pH (8.4–8.8 and smaller ones at higher solution pH (10.8–11.3. The color of CdS products changed with solution pH and reaction temperature; those synthesized at lower pH and temperature were of green-yellow color, whereas those formed at higher pH and temperature were of orange-yellow color. A good photovoltage was observed in CdS:poly(3-hexylthiophene solar cells with spherical CdS particles. This is due to the good dispersion of CdS nanoparticles in P3HT solution that led to a large interface area between the organic and inorganic semiconductors. Higher photocurrent density was obtained in green-yellow CdS particles of lower defect density. The efficient microwave chemistry accelerated the hydrolysis of thiourea in pH lower than 9 and produced monodisperse spherical CdS nanoparticles suitable for solar cell applications.

Deposition kinetics of quantum dots and polystyrene latex nanoparticles onto alumina: role of water chemistry and particle coating.

Science.gov (United States)

Quevedo, Ivan R; Olsson, Adam L J; Tufenkji, Nathalie

2013-03-05

A clear understanding of the factors controlling the deposition behavior of engineered nanoparticles (ENPs), such as quantum dots (QDs), is necessary for predicting their transport and fate in natural subsurface environments and in water filtration processes. A quartz crystal microbalance with dissipation monitoring (QCM-D) was used to study the effect of particle surface coatings and water chemistry on the deposition of commercial QDs onto Al2O3. Two carboxylated QDs (CdSe and CdTe) with different surface coatings were compared with two model nanoparticles: sulfate-functionalized (sPL) and carboxyl-modified (cPL) polystyrene latex. Deposition rates were assessed over a range of ionic strengths (IS) in simple electrolyte (KCl) and in electrolyte supplemented with two organic molecules found in natural waters; namely, humic acid and rhamnolipid. The Al2O3 collector used here is selected to be representative of oxide patches found on the surface of aquifer or filter grains. Deposition studies showed that ENP deposition rates on bare Al2O3 generally decreased with increasing salt concentration, with the exception of the polyacrylic-acid (PAA) coated CdTe QD which exhibited unique deposition behavior due to changes in the conformation of the PAA coating. QD deposition rates on bare Al2O3 were approximately 1 order of magnitude lower than those of the polystyrene latex nanoparticles, likely as a result of steric stabilization imparted by the QD surface coatings. Adsorption of humic acid or rhamnolipid on the Al2O3 surface resulted in charge reversal of the collector and subsequent reduction in the deposition rates of all ENPs. Moreover, the ratio of the two QCM-D output parameters, frequency and dissipation, revealed key structural information of the ENP-collector interface; namely, on bare Al2O3, the latex particles were rigidly attached as compared to the more loosely attached QDs. This study emphasizes the importance of considering the nature of ENP coatings as well

In-site synthesis of monodisperse, oleylamine-capped Ag nanoparticles through microemulsion approach

Science.gov (United States)

Chen, Shun; Ju, Yanyun; Guo, Yi; Xiong, Chuanxi; Dong, Lijie

2017-03-01

Ag NPs were in-site synthesized through microemulsion method by reducing silver acetate with oleylamine-mediated at 70 °C with highly monodisperse and narrow size from 10 to 20 nm. The synthesis of Ag NPs was aided by oleylamine and the role of oleylamine was researched. This in-site synthesis approach to Ag NPs was reproducibility and high yield more than 80% with stable store about 6 months.

The effects of surface-charged submicron polystyrene particles on the structure and performance of PSF forward osmosis membrane

Science.gov (United States)

Zuo, Hao-Ran; Fu, Jia-Bei; Cao, Gui-Ping; Hu, Nian; Lu, Hui; Liu, Hui-Qing; Chen, Peng-Peng; Yu, Jie

2018-04-01

Monodisperse surface-charged submicron polystyrene particles were designed, synthesized, and blended into polysulfone (PSF) support layer to prepare forward osmosis (FO) membrane with high performance. The membrane incorporated with particles were characterized with respect to morphology, porosity, and internal osmotic pressure (IOP). Results showed that the polymer particles not only increased the hydrophilicity and porosity of support layer, but also generated considerable IOP, which helped markedly decreasing the structure parameter from 1550 to 670 μm. The measured mass transfer parameters further confirmed the beneficial effects of the surface-charged submicron polymer particles on the performance of FO membrane. For instance, the water permeability coefficient (5.37 L m-2 h-1 bar-1) and water flux (49.7 L m-2 h-1) of the FO membrane incorporated with 5 wt% particles were almost twice as much as that of FO membrane without incorporation. This study suggests that monodisperse surface-charged submicron polymer particles are potential modifiers for improving the performance of FO membranes.

Measurement of filtration efficiency of Nuclepore filters challenged with polystyrene latex nanoparticles: experiments and modeling

International Nuclear Information System (INIS)

Ling, Tsz Yan; Wang Jing; Pui, David Y. H.

2011-01-01

Membrane filtration has been demonstrated to be effective for the removal of liquid-borne nanoparticles (NPs). Such technique can be applied to purify and disinfect drinking water as well as remove NPs in highly pure chemicals used in the industries. This study aims to study the filtration process of a model membrane filter, the Nuclepore filter. Experiments were carried out using standard filtration tools and the nanoparticle tracking analysis (NTA) technique was used to measure particle (50–500 nm) concentration upstream and downstream of the filter to determine the filtration efficiency. The NTA technique has been calibrated using 150-nm polystyrene latex particles to determine its accuracy of particle concentration measurement. Measurements were found reliable within a certain concentration limit (about 10 8 –10 10 particles/cm 3 ), which is dependent on the camera settings during the measurement. Experimental results are comparable with previously published data obtained using the aerosolization method, validating the capability of the NTA technique. The capillary tube model modified from that developed for aerosol filtration was found to be useful to represent the experimental results, when a sticking coefficient of 0.15 is incorporated. This suggests that only 15% of the particle collisions with the filter results in successful attachment. The small sticking coefficient found can be explained by the unfavorable surface interactions between the particles and the filter medium.

Histidine-functionalized carbon-based dot-Zinc(II) nanoparticles as a novel stabilizer for Pickering emulsion synthesis of polystyrene microspheres.

Science.gov (United States)

Ruiyi, Li; Zaijun, Li; Junkang, Liu

2017-05-01

Carbon-based dots (CDs) are nanoparticles with size-dependent optical and electronic properties that have been widely applied in energy-efficient displays and lighting, photovoltaic devices and biological markers. However, conventional CDs are difficult to be used as ideal stabilizer for Pickering emulsion due to its irrational amphiphilic structure. The study designed and synthesized a new histidine-functionalized carbon dot-Zinc(II) nanoparticles, which is termed as His-CD-Zn. The His-CD was made via one-step hydrothermal treatment of histidine and maleic acid. The His-CD reacted with Zn 2+ to form His-CD-Zn. The as-prepared His-CD-Zn was used as a solid particle surfactant for stabilizing styrene-in-water emulsion. The Pickering emulsion exhibits high stability and sensitive pH-switching behaviour. The introduction of S 2 O 8 2- triggers the emulsion polymerization of styrene. The resulted polystyrene microsphere was well coated with His-CDs on the surface. It was successfully used as an ideal adsorbent for removal of heavy metallic ions from water with high adsorption capacity. The study also provides a prominent approach for fabrication of amphiphilic carbon-based nanoparticles for stabilizing Pickering emulsion. Copyright © 2017 Elsevier Inc. All rights reserved.

In-site synthesis of monodisperse, oleylamine-capped Ag nanoparticles through microemulsion approach

Energy Technology Data Exchange (ETDEWEB)

Chen, Shun; Ju, Yanyun [Wuhan University of Technology, School of Materials Science and Engineering (China); Guo, Yi [Wuhan University of Technology, Center for Materials Research and Analysis (China); Xiong, Chuanxi; Dong, Lijie, E-mail: dong@whut.edu.cn [Wuhan University of Technology, School of Materials Science and Engineering (China)

2017-03-15

Ag NPs were in-site synthesized through microemulsion method by reducing silver acetate with oleylamine-mediated at 70 °C with highly monodisperse and narrow size from 10 to 20 nm. The synthesis of Ag NPs was aided by oleylamine and the role of oleylamine was researched. This in-site synthesis approach to Ag NPs was reproducibility and high yield more than 80% with stable store about 6 months.

Size-selective separation of polydisperse gold nanoparticles in supercritical ethane.

Science.gov (United States)

Williams, Dylan P; Satherley, John

2009-04-09

The aim of this study was to use supercritical ethane to selectively disperse alkanethiol-stabilized gold nanoparticles of one size from a polydisperse sample in order to recover a monodisperse fraction of the nanoparticles. A disperse sample of metal nanoparticles with diameters in the range of 1-5 nm was prepared using established techniques then further purified by Soxhlet extraction. The purified sample was subjected to supercritical ethane at a temperature of 318 K in the pressure range 50-276 bar. Particles were characterized by UV-vis absorption spectroscopy, TEM, and MALDI-TOF mass spectroscopy. The results show that with increasing pressure the dispersibility of the nanoparticles increases, this effect is most pronounced for smaller nanoparticles. At the highest pressure investigated a sample of the particles was effectively stripped of all the smaller particles leaving a monodisperse sample. The relationship between dispersibility and supercritical fluid density for two different size samples of alkanethiol-stabilized gold nanoparticles was considered using the Chrastil chemical equilibrium model.

Response of three instruments devoted to surface-area for monodisperse and polydisperse aerosols in molecular and transition regimes

International Nuclear Information System (INIS)

Bau, Sebastien; Witschger, Olivier; Gensdarmes, Francois; Thomas, Dominique

2011-01-01

An increasing number of experimental and theoretical studies focus on airborne nanoparticles (NP) in relation with many aspects of risk assessment. Indeed, our understanding of the hazards, the actual exposures in the workplace and the limits of engineering controls and personal protective equipment with regard to NP are still under development. Several studies have already identified surface-area as an important determinant of low solubility nanoparticles toxicity. As a consequence, the concept that surface-area could be a relevant metric for characterizing exposure to low solubility airborne NP has been proposed [1]. To provide NP surface-area concentration, some direct-reading instruments have been designed, based on diffusion charging. The actual available instruments providing airborne NP surface-area concentration are studied in this work: LQ1-DC (Matter Engineering), AeroTrak T M 9000 (TSI) and NSAM (TSI model 3550). Their performances regarding monodisperse carbon NP have been investigated by Bau et al.. This work aims at completing the instruments characterization regarding monodisperse NP of other chemical composition (aluminium, copper, silver) and studying their performances against polydisperse aerosols of NP.

Response of three instruments devoted to surface-area for monodisperse and polydisperse aerosols in molecular and transition regimes

Energy Technology Data Exchange (ETDEWEB)

Bau, Sebastien; Witschger, Olivier [Institut National de Recherche et de Securite (INRS), Laboratoire de Metrologie des Aerosols, Rue du Morvan, CS 60027, 54519 Vandoeuvre Cedex (France); Gensdarmes, Francois [Institut de Radioprotection et de Surete Nucleaire (IRSN), Laboratoire de Physique et de Metrologie des Aerosols, BP 68, 91192 Gif-sur-Yvette (France); Thomas, Dominique, E-mail: sebastien.bau@inrs.fr [Laboratoire Reactions et Genie des Procedes (LRGP), groupe SAFE, 1 rue Grandville, BP 20041, 54001 Nancy Cedex (France)

2011-07-06

An increasing number of experimental and theoretical studies focus on airborne nanoparticles (NP) in relation with many aspects of risk assessment. Indeed, our understanding of the hazards, the actual exposures in the workplace and the limits of engineering controls and personal protective equipment with regard to NP are still under development. Several studies have already identified surface-area as an important determinant of low solubility nanoparticles toxicity. As a consequence, the concept that surface-area could be a relevant metric for characterizing exposure to low solubility airborne NP has been proposed [1]. To provide NP surface-area concentration, some direct-reading instruments have been designed, based on diffusion charging. The actual available instruments providing airborne NP surface-area concentration are studied in this work: LQ1-DC (Matter Engineering), AeroTrak{sup TM} 9000 (TSI) and NSAM (TSI model 3550). Their performances regarding monodisperse carbon NP have been investigated by Bau et al.. This work aims at completing the instruments characterization regarding monodisperse NP of other chemical composition (aluminium, copper, silver) and studying their performances against polydisperse aerosols of NP.

Magnetic properties of γ-Fe2O3 nanoparticles incorporated in a polystyrene resin matrix

Science.gov (United States)

Vaishnava, P. P.; Senaratne, U.; Buc, E. C.; Naik, R.; Naik, V. M.; Tsoi, G. M.; Wenger, L. E.

2007-07-01

γ-Fe2O3 magnetic nanoparticles ranging in average diameter from 3to10nm were synthesized into a polystyrene resin matrix by an ion-exchange method and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Mössbauer spectroscopy, and SQUID magnetometry. The average particle size as determined from XRD and TEM was found to be strongly dependent upon the initial Fe valence state of the starting chloride salt(s) and on the number of steps that the salt introduction and ion-exchange process were repeated. Regardless of the initial Fe valence state and processing conditions, Mössbauer spectroscopy confirmed that the Fe in the resulting nanoparticles existed only as Fe(III) ions and that γ-Fe2O3 was the only phase present. The values of the saturation magnetization at 5K were found to be dependent upon the processing conditions and ranged from 203to333emu/cm3 , which are significantly smaller than the bulk value (408emu/cm3) for γ-Fe2O3 . As expected, the nanoparticles exhibited superparamagnetic behavior with the magnetic moments becoming frozen with decreasing temperature as evidenced by the appearance of a six-line splitting in the Mössbauer spectra, a bifurcation in the zero-field-cooled (ZFC) and field-cooled (FC) magnetizations, and an opening in the MV -vs- H hysteresis curves. The values of magnetic anisotropy constant (1.2-2.1×106ergs/cm3) determined from the differences between the ZFC and FC magnetizations were found to be higher than the bulk value (1.1×105ergs/cm3) for γ-Fe2O3 , and are probably due to surface effects. Likewise, the nanoparticle size distributions as deduced from the blocking temperature distribution function f(TB) based on fits to the difference in the ZFC and FC magnetization curves as well as from fits of the MV -vs- H curves in the superparamagnetic regime with a Langevin function indicate fairly broad distributions of particle sizes with the particle sizes being comparable to those deduced from XRD

Monodispersed ZIF-8 particles with enhanced performance for CO2 adsorption and heterogeneous catalysis

Science.gov (United States)

Guan, Yebin; Shi, Juanjuan; Xia, Ming; Zhang, Jun; Pang, Zhenfeng; Marchetti, Alessandro; Wang, Xiaohong; Cai, Jingsong; Kong, Xueqian

2017-11-01

Monodispersed zeolitic imidazolate frameworks (ZIFs) were prepared with a simple method using dimethylsulfoxide (DMSO) as solvent. This method yields ZIF-8 nanoparticles with a narrow particle size distribution of 90-110 nm and the dispersion is highly stable against agglomeration. These particles have larger nanosized porosity and enhanced CO2 adsorption capability compared to ZIF-8 prepared with different solvents such as methanol or N, N-dimethyl formamide. Their uniform size and surface chemistry also lead to superior performance in the Knoevenagel condensation reactions. The ZIF-8 nanoparticles possess high thermal stability up to 550 °C and the preparation steps are easy for scaling up which are favorable for industrial applications.

Structural and rectifying junction properties of self-assembled ZnO nanoparticles in polystyrene diblock copolymers on (1 0 0)Si substrates

Science.gov (United States)

Ali, H. A.; Iliadis, A. A.; Martinez-Miranda, L. J.; Lee, U.

2006-06-01

The structural and electronic transport properties of self-assembled ZnO nanoparticles in polystyrene-acrylic acid, [PS] m/[PAA] n, diblock copolymer on p-type (1 0 0)Si substrates are reported for the first time. Four different block repeat unit ratios ( m/ n) of 159/63, 139/17,106/17, and 106/4, were examined in order to correlate the physical parameters (size, density) of the nanoparticles with the copolymer block lengths m and n. We established that the self-assembled ZnO nanoparticle average size increased linearly with minority block length n, while the average density decreased exponentially with majority block length m. Average size varied from 20 nm to 250 nm and average density from 3.5 × 10 7 cm -2 to 1 × 10 10 cm -2, depending on copolymer parameters. X-ray diffraction studies showed the particles to have a wurtzite crystal structure with the (1 0 0) being the dominant orientation. Room temperature current-voltage characteristics measured for an Al/ZnO-nanocomposite/Si structure exhibited rectifying junction properties and indicated the formation of Al/ZnO-nanocomposite Schottky type junction with a barrier height of 0.7 V.

Synthesis and characterization of CoPt nanoparticles prepared by room temperature chemical reduction with PAMAM dendrimer as template.

Science.gov (United States)

Wan, Haiying; Shi, Shifan; Bai, Litao; Shamsuzzoha, Mohammad; Harrell, J W; Street, Shane C

2010-08-01

We describe an approach to synthesize monodisperse CoPt nanoparticles with dendrimer as template by a simple chemical reduction method in aqueous solution using NaBH4 as reducing agent at room temperature. The as-made CoPt nanoparticles buried in the dendrimer matrix have the chemically disordered fcc structure and can be transformed to the fct phase after annealing at 700 degrees C. This is the first report of dendrimer-mediated room temperature synthesis of monodisperse magnetic nanoparticles in aqueous solution.

Effect of Surface Modification of Nanosilica on the Viscoelastic Properties of Its Polystyrene Nanocomposite

Directory of Open Access Journals (Sweden)

M. Mortezaei

2008-12-01

Full Text Available The preparation and characterization of the vinyltriethoxysilane-modified silica nanoparticles were investigated. Also the surface tension of polystyrene, native (hydrophilic silica and silane-modified (hydrophobic silica were determined. Two kinds of polystyrene/silica (treated and non-treated nanocomposites were prepared with different filler loadings by solution method. Their viscoelastic properties were studied by dynamic stress controlled rotary shear rheometer. Solid-like response of polystyrene/native silica nanocomposites were observed in the terminal zone. Solid inclusionsincrease the storage modulus more than the loss modulus, hence decrease the material damping. By increasing filler volume fraction, the particles tend to agglomerate and build clusters. The presence of clusters increases the viscosity, the moduli and the viscoelastic non-linearity of the composites.Treating the filler surface reduces its tendency to agglomerate as well as the adhesion between the particles and the polystyrene, leading to lower viscosity and interfacial slippage. Also the loss modulus peak is affected significantly by the particle surface area and its surface property in silica-filled polystyrene, which corresponds to its glass transition.

Monodisperse, submicrometer-scale platinum colloidal spheres with high electrocatalytic activity

Energy Technology Data Exchange (ETDEWEB)

Zhang, Lixue; Wang, Liang; Guo, Shaojun; Zhai, Junfeng; Dong, Shaojun; Wang, Erkang [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Graduate School of the Chinese Academy of Sciences, 130022 Jilin, Changchun (China)

2009-02-15

Monodisperse, submicrometer-scale platinum (Pt) colloidal spheres were prepared through a simple direct chemical reduction of p-phenylenediamine (PPD)-chloroplatinic acid (H{sub 2}PtCl{sub 6}) coordination polymer colloids. It was found that the prepared Pt colloids had the similar size and morphology with their coordination polymer precursors, and the prepared Pt colloids with rough surfaces were three-dimensional (3D) structured assemblies of high-density small Pt nanoparticles. The electrochemical experiments confirmed that the prepared Pt colloids possessed a high electrocatalytic activity towards mainly four-electron reduction of dioxygen to water, making the prepared Pt colloids potential candidates for the efficient cathode material in fuel cells. (author)

Labeling and exocytosis of secretory compartments in RBL mastocytes by polystyrene and mesoporous silica nanoparticles

Directory of Open Access Journals (Sweden)

Ekkapongpisit M

2012-04-01

Full Text Available Maneerat Ekkapongpisit1,*, Antonino Giovia1,*, Giuseppina Nicotra1, Matteo Ozzano1, Giuseppe Caputo2,3, Ciro Isidoro1 1Laboratory of Molecular Pathology and Nanobioimaging, Department of Health Sciences, Università del Piemonte Orientale "A. Avogadro", Novara, Italy; 2Department of Chemistry, University of Turin, Turin, 3Cyanine Technology SpA, Torino, Italy *These authors contributed equally to this workBackground: For a safe ‘in vivo’ biomedical utilization of nanoparticles, it is essential to assess not only biocompatibility, but also the potential to trigger unwanted side effects at both cellular and tissue levels. Mastocytes (cells having secretory granules containing cytokines, vasoactive amine, and proteases play a pivotal role in the immune and inflammatory responses against exogenous toxins. Mastocytes are also recruited in the tumor stroma and are involved in tumor vascularization and growth.Aim and methods: In this work, mastocyte-like rat basophilic leukemia (RBL cells were used to investigate whether carboxyl-modified 30 nm polystyrene (PS nanoparticles (NPs and naked mesoporous silica (MPS 10 nm NPs are able to label the secretory inflammatory granules, and possibly induce exocytosis of these granules. Uptake, cellular retention and localization of fluorescent NPs were analyzed by cytofluorometry and microscope imaging.Results: Our findings were that: (1 secretory granules of mastocytes are accessible by NPs via endocytosis; (2 PS and MPS silica NPs label two distinct subpopulations of inflammatory granules in RBL mastocytes; and (3 PS NPs induce calcium-dependent exocytosis of inflammatory granules.Conclusion: These findings highlight the value of NPs for live imaging of inflammatory processes, and also have important implications for the clinical use of PS-based NPs, due to their potential to trigger the unwanted activation of mastocytes.Keywords: secretory lysosomes, inflammation, nanoparticles, vesicular traffic

Synthesis of indium nanoparticles at ambient temperature; simultaneous phase transfer and ripening

Energy Technology Data Exchange (ETDEWEB)

Aghazadeh Meshgi, Mohammad; Kriechbaum, Manfred [Graz University of Technology, Institute of Inorganic Chemistry (Austria); Biswas, Subhajit; Holmes, Justin D., E-mail: j.holmes@ucc.ie [University College Cork, Materials Chemistry and Analysis Group, Department of Chemistry and the Tyndall National Institute (Ireland); Marschner, Christoph, E-mail: christoph.marschner@tugraz.at [Graz University of Technology, Institute of Inorganic Chemistry (Austria)

2016-12-15

The synthesis of size-monodispersed indium nanoparticles via an innovative simultaneous phase transfer and ripening method is reported. The formation of nanoparticles occurs in a one-step process instead of well-known two-step phase transfer approaches. The synthesis involves the reduction of InCl{sub 3} with LiBH{sub 4} at ambient temperature and although the reduction occurs at room temperature, fine indium nanoparticles, with a mean diameter of 6.4 ± 0.4 nm, were obtained directly in non-polar n-dodecane. The direct synthesis of indium nanoparticles in n-dodecane facilitates their fast formation and enhances their size-monodispersity. In addition, the nanoparticles were highly stable for more than 2 months. The nanoparticles were characterised by dynamic light scattering (DLS), small angle X-ray scattering (SAXS), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS) and Fourier transform infrared (FT-IR) spectroscopy to determine their morphology, structure and phase purity.

Synthesis of Ag-coated polystyrene colloids by an improved surface seeding and shell growth technique

International Nuclear Information System (INIS)

Tian Chungui; Wang Enbo; Kang Zhenhui; Mao Baodong; Zhang Chao; Lan Yang; Wang Chunlei; Song Yanli

2006-01-01

In this paper, an improved surface seeding and shell growth technique was developed to prepare Ag-polystyrene core shell composite. Polyethyleneimine (PEI) could act as the linker between Ag ions (Ag nanoparticles) and polystyrene (PS) colloids and the reducing agent in the formation of Ag nanoparticles. Due to the multi-functional characteristic of PEI, Ag seeds formed in-situ and were immobilized on the surface of PEI-modified PS colloids and no free Ag clusters coexist with the Ag 'seeding' PS colloids in the system. Then, the additional agents could be added into the resulting dispersions straightly to produce a thick Ag nanoshell. The Ag nanoshell with controllable thickness was formed on the surface of PS by the 'one-pot' surface seeding and shell growth method. The Ag-coverage increased gradually with the increasing of mass ratio of AgNO 3 /PS. The optical properties of the Ag-PS colloids could be tailored by changing the coverage of Ag. - Graphical abstract: An improved surface seeding and shell growth technique was developed to prepare Ag-polystyrene core shell composite. The optical properties of the Ag-PS colloids could be tailored by changing the coverage of Ag. Display Omitted

Strongly Iridescent Hybrid Photonic Sensors Based on Self-Assembled Nanoparticles for Hazardous Solvent Detection

Directory of Open Access Journals (Sweden)

Ayaka Sato

2018-03-01

Full Text Available Facile detection and the identification of hazardous organic solvents are essential for ensuring global safety and avoiding harm to the environment caused by industrial wastes. Here, we present a simple method for the fabrication of silver-coated monodisperse polystyrene nanoparticle photonic structures that are embedded into a polydimethylsiloxane (PDMS matrix. These hybrid materials exhibit a strong green iridescence with a reflectance peak at 550 nm that originates from the close-packed arrangement of the nanoparticles. This reflectance peak measured under Wulff-Bragg conditions displays a 20 to 50 nm red shift when the photonic sensors are exposed to five commonly employed and highly hazardous organic solvents. These red-shifts correlate well with PDMS swelling ratios using the various solvents, which suggests that the observable color variations result from an increase in the photonic crystal lattice parameter with a similar mechanism to the color modulation of the chameleon skin. Dynamic reflectance measurements enable the possibility of clearly identifying each of the tested solvents. Furthermore, as small amounts of hazardous solvents such as tetrahydrofuran can be detected even when mixed with water, the nanostructured solvent sensors we introduce here could have a major impact on global safety measures as innovative photonic technology for easily visualizing and identifying the presence of contaminants in water.

Three strategies to stabilise nearly monodispersed silver nanoparticles in aqueous solution

Science.gov (United States)

Stevenson, Amadeus PZ; Blanco Bea, Duani; Civit, Sergi; Antoranz Contera, Sonia; Iglesias Cerveto, Alberto; Trigueros, Sonia

2012-02-01

Silver nanoparticles are extensively used due to their chemical and physical properties and promising applications in areas such as medicine and electronics. Controlled synthesis of silver nanoparticles remains a major challenge due to the difficulty in producing long-term stable particles of the same size and shape in aqueous solution. To address this problem, we examine three strategies to stabilise aqueous solutions of 15 nm citrate-reduced silver nanoparticles using organic polymeric capping, bimetallic core-shell and bimetallic alloying. Our results show that these strategies drastically improve nanoparticle stability by distinct mechanisms. Additionally, we report a new role of polymer functionalisation in preventing further uncontrolled nanoparticle growth. For bimetallic nanoparticles, we attribute the presence of a higher valence metal on the surface of the nanoparticle as one of the key factors for improving their long-term stability. Stable silver-based nanoparticles, free of organic solvents, will have great potential for accelerating further environmental and nanotoxicity studies. PACS: 81.07.-b; 81.16.Be; 82.70.Dd.

Monodispersed Zinc Oxide Nanoparticle-Dye Dyads and Triads

Energy Technology Data Exchange (ETDEWEB)

Gladfelter, Wayne L. [Univ. of Minnesota, Minneapolis, MN (United States). Dept. of Chemistry; Blank, David A. [Univ. of Minnesota, Minneapolis, MN (United States). Dept. of Chemistry; Mann, Kent R. [Univ. of Minnesota, Minneapolis, MN (United States). Dept. of Chemistry

2017-06-22

events at a fundamental level. This was combined with the synthesis of a broad range of sensitizers that provide systematic variation of the energetics, excited state dynamics, structure and interfacial bonding. The key is that the monodisperse nature and high dispersibility of the ZnO NCs made these experiments reproducible; in essence, the measurements were on discrete molecular species rather than on the complicated mixtures that resulted from the typical fabrication of functional photovoltaic cells. The monodispersed nature of the NCs also allowed the use of quantum confinement to investigate the role of donor/acceptor energetic alignment in chemically identical systems. The results added significantly to our basic understanding of energy and charge transfer events at molecule-semiconductor interfaces and will help the R&D community realize zinc oxide's full potential in solar cell applications.

Method of synthesizing tungsten nanoparticles

Science.gov (United States)

Thoma, Steven G; Anderson, Travis M

2013-02-12

A method to synthesize tungsten nanoparticles has been developed that enables synthesis of nanometer-scale, monodisperse particles that can be stabilized only by tetrahydrofuran. The method can be used at room temperature, is scalable, and the product concentrated by standard means. Since no additives or stabilizing surfactants are required, this method is particularly well suited for producing tungsten nanoparticles for dispersion in polymers. If complete dispersion is achieved due to the size of the nanoparticles, then the optical properties of the polymer can be largely maintained.

Comparison of the cytotoxic effect of polystyrene latex nanoparticles on planktonic cells and bacterial biofilms

International Nuclear Information System (INIS)

Nomura, Toshiyuki; Fujisawa, Eri; Itoh, Shikibu; Konishi, Yasuhiro

2016-01-01

The cytotoxic effect of positively charged polystyrene latex nanoparticles (PSL NPs) was compared between planktonic bacterial cells and bacterial biofilms using confocal laser scanning microscopy, atomic force microscopy, and a colony counting method. Pseudomonas fluorescens, which is commonly used in biofilm studies, was employed as the model bacteria. We found that the negatively charged bacterial surface of the planktonic cells was almost completely covered with positively charged PSL NPs, leading to cell death, as indicated by the NP concentration being greater than that required to achieve single layer coverage. In addition, the relationship between surface coverage and cell viability of P. fluorescens cells correlated well with the findings in other bacterial cells (Escherichia coli and Lactococcuslactis). However, most of the bacterial cells that formed the biofilm were viable despite the positively charged PSL NPs being highly toxic to planktonic bacterial cells. This indicated that bacterial cells embedded in the biofilm were protected by self-produced extracellular polymeric substances (EPS) that provide resistance to antibacterial agents. In conclusion, mature biofilms covered with EPS exhibit resistance to NP toxicity as well as antibacterial agents.

Comparison of the cytotoxic effect of polystyrene latex nanoparticles on planktonic cells and bacterial biofilms

Energy Technology Data Exchange (ETDEWEB)

Nomura, Toshiyuki, E-mail: nomura@chemeng.osakafu-u.ac.jp; Fujisawa, Eri; Itoh, Shikibu; Konishi, Yasuhiro [Osaka Prefecture University, Department of Chemical Engineering (Japan)

2016-06-15

The cytotoxic effect of positively charged polystyrene latex nanoparticles (PSL NPs) was compared between planktonic bacterial cells and bacterial biofilms using confocal laser scanning microscopy, atomic force microscopy, and a colony counting method. Pseudomonas fluorescens, which is commonly used in biofilm studies, was employed as the model bacteria. We found that the negatively charged bacterial surface of the planktonic cells was almost completely covered with positively charged PSL NPs, leading to cell death, as indicated by the NP concentration being greater than that required to achieve single layer coverage. In addition, the relationship between surface coverage and cell viability of P. fluorescens cells correlated well with the findings in other bacterial cells (Escherichia coli and Lactococcuslactis). However, most of the bacterial cells that formed the biofilm were viable despite the positively charged PSL NPs being highly toxic to planktonic bacterial cells. This indicated that bacterial cells embedded in the biofilm were protected by self-produced extracellular polymeric substances (EPS) that provide resistance to antibacterial agents. In conclusion, mature biofilms covered with EPS exhibit resistance to NP toxicity as well as antibacterial agents.

Comparison of the cytotoxic effect of polystyrene latex nanoparticles on planktonic cells and bacterial biofilms

Science.gov (United States)

Nomura, Toshiyuki; Fujisawa, Eri; Itoh, Shikibu; Konishi, Yasuhiro

2016-06-01

The cytotoxic effect of positively charged polystyrene latex nanoparticles (PSL NPs) was compared between planktonic bacterial cells and bacterial biofilms using confocal laser scanning microscopy, atomic force microscopy, and a colony counting method. Pseudomonas fluorescens, which is commonly used in biofilm studies, was employed as the model bacteria. We found that the negatively charged bacterial surface of the planktonic cells was almost completely covered with positively charged PSL NPs, leading to cell death, as indicated by the NP concentration being greater than that required to achieve single layer coverage. In addition, the relationship between surface coverage and cell viability of P. fluorescens cells correlated well with the findings in other bacterial cells ( Escherichia coli and Lactococcus lactis). However, most of the bacterial cells that formed the biofilm were viable despite the positively charged PSL NPs being highly toxic to planktonic bacterial cells. This indicated that bacterial cells embedded in the biofilm were protected by self-produced extracellular polymeric substances (EPS) that provide resistance to antibacterial agents. In conclusion, mature biofilms covered with EPS exhibit resistance to NP toxicity as well as antibacterial agents.

Evaluating the uptake and intracellular fate of polystyrene nanoparticles by primary and hepatocyte cell lines in vitro

International Nuclear Information System (INIS)

Johnston, Helinor J.; Semmler-Behnke, Manuela; Brown, David M.; Kreyling, Wolfgang; Tran, Lang; Stone, Vicki

2010-01-01

Nanoparticles (NPs) are being used within diverse applications such as medicines, clothing, cosmetics and food. In order to promote the safe development of such nanotechnologies it is essential to assess the potential adverse health consequences associated with human exposure. The liver is recognised as a target site for NP toxicity, due to NP accumulation within this organ subsequent to injection, inhalation or instillation. The uptake of fluorescent polystyrene carboxylated particles (20 nm or 200 nm diameter) by hepatocytes was determined using confocal microscopy; with cells imaged 'live' during particle exposure or after exposure within fixed cells. Comparisons between the uptake of polystyrene particles by primary rat hepatocytes, and human hepatocyte cell lines (C3A and HepG2) were made. Uptake of particles by hepatocytes was size, time, and serum dependent. Specifically, the uptake of 200 nm particles was limited, but 20 nm NPs were internalised by all cell types from 10 min onwards. At 10 min, 20 nm NP fluorescence co-localised with the tubulin cytoskeleton staining; after 30 min NP fluorescence compartmentalised into structures located within and/or between cells. The fate of internalised NPs was considered and they were not contained within early endosomes or lysosomes, but within mitochondria of cell lines. NPs accumulated within bile canaliculi to a limited extent, which suggests that NPs can be eliminated within bile. This is in keeping with the finding that gold NPs were eliminated in bile following intravenous injection into rats. The findings were, in the main, comparable between primary rat hepatocytes and the different human hepatocyte cell lines.

Simulations of super-structure domain walls in two dimensional assemblies of magnetic nanoparticles

DEFF Research Database (Denmark)

Jordanovic, Jelena; Beleggia, Marco; Schiøtz, Jakob

2015-01-01

We simulate the formation of domain walls in two-dimensional assemblies of magnetic nanoparticles. Particle parameters are chosen to match recent electron holography and Lorentz microscopy studies of almost monodisperse cobalt nanoparticles assembled into regular, elongated lattices. As the parti......We simulate the formation of domain walls in two-dimensional assemblies of magnetic nanoparticles. Particle parameters are chosen to match recent electron holography and Lorentz microscopy studies of almost monodisperse cobalt nanoparticles assembled into regular, elongated lattices...... taking the role of the atomic spins. The coupling is, however, different. The superspins interact only by dipolar interactions as exchange coupling between individual nanoparticles may be neglected due to interparticle spacing. We observe that it is energetically favorable to introduce domain walls...... oriented along the long dimension of nanoparticle assemblies rather than along the short dimension. This is unlike what is typically observed in continuous magnetic materials, where the exchange interaction introduces an energetic cost proportional to the area of the domain walls. Structural disorder...

Tribological characteristics of monodispersed cerium borate nanospheres in biodegradable rapeseed oil lubricant

Energy Technology Data Exchange (ETDEWEB)

Boshui, Chen, E-mail: boshuichen@163.com; Kecheng, Gu; Jianhua, Fang; Jiang, Wu; Jiu, Wang; Nan, Zhang

2015-10-30

Graphical abstract: - Highlights: • Monodispersed stearic acid-capped cerium borate composite nanoparticles were prepared by hydrothermal method. Their morphologies, element compositions, size distributions, crystal and chemical structures, hydrophobic characteristics were also characterized. • The surface-capped cerium borate nanoparticles exhibited excellent dispersing stability in rapeseed oil. As new lubricating additives, they were also outstanding in enhancing friction-reducing and anti-wear capacities of rapeseed oil in biodegradable rapeseed oil. The results presented in this paper would be of important significance for developing green lubricants and lubricant additives. • The prominent tribological performances of SA/CeBO{sub 3} in rapeseed oil were investigated and attributed to the formation of a composite boundary lubrication film mainly composed of lubricous tribochemical species on the tribo-surfaces. - Abstract: Stearic acid-capped cerium borate composite nanoparticles, abbreviated as SA/CeBO{sub 3}, were prepared by hydrothermal method. The morphologies, element compositions, size distributions, crystal and chemical structures, hydrophobic characteristics, of SA/CeBO{sub 3} were characterized by scanning electron microscope, energy dispersive X-ray spectrometer, dynamic laser particle size analyzer, X-ray diffraction, and Fourier transform infrared spectrometer, respectively. The friction and wear performances of SA/CeBO{sub 3} as a lubricating additive in a rapeseed oil were evaluated on a four-ball tribo-tester. The tribochemical characteristics of the worn surfaces were investigated by X-ray photoelectron spectroscopy. The results showed that the hydrophobic SA/CeBO{sub 3} were monodispersed nanospheres with an average diameter of 8 nm, and exhibited excellent dispersing stability in rapeseed oil. Meanwhile, SA/CeBO{sub 3} nanospheres were outstanding in enhancing friction-reducing and anti-wear capacities of rapeseed oil. The prominent

Development and hazard assessment of nanoparticles

NARCIS (Netherlands)

Bhattacharjee, S.

2012-01-01

A series of highly monodisperse silicon nanoparticles (Si NP) with either
positively (amine), neutral (azide) or negatively (carboxylic acid) charged
covalently attached organic monolayers were synthesized and investigated for
their cytotoxicity. Infrared data confirmed the

WO3 Nanofiber-Based Biomarker Detectors Enabled by Protein-Encapsulated Catalyst Self-Assembled on Polystyrene Colloid Templates.

Science.gov (United States)

Choi, Seon-Jin; Kim, Sang-Joon; Cho, Hee-Jin; Jang, Ji-Soo; Lin, Yi-Min; Tuller, Harry L; Rutledge, Gregory C; Kim, Il-Doo

2016-02-17

A novel catalyst functionalization method, based on protein-encapsulated metallic nanoparticles (NPs) and their self-assembly on polystyrene (PS) colloid templates, is used to form catalyst-loaded porous WO3 nanofibers (NFs). The metallic NPs, composed of Au, Pd, or Pt, are encapsulated within a protein cage, i.e., apoferritin, to form unagglomerated monodispersed particles with diameters of less than 5 nm. The catalytic NPs maintain their nanoscale size, even following high-temperature heat-treatment during synthesis, which is attributed to the discrete self-assembly of NPs on PS colloid templates. In addition, the PS templates generate open pores on the electrospun WO3 NFs, facilitating gas molecule transport into the sensing layers and promoting active surface reactions. As a result, the Au and Pd NP-loaded porous WO3 NFs show superior sensitivity toward hydrogen sulfide, as evidenced by responses (R(air)/R(gas)) of 11.1 and 43.5 at 350 °C, respectively. These responses represent 1.8- and 7.1-fold improvements compared to that of dense WO3 NFs (R(air)/R(gas) = 6.1). Moreover, Pt NP-loaded porous WO3 NFs exhibit high acetone sensitivity with response of 28.9. These results demonstrate a novel catalyst loading method, in which small NPs are well-dispersed within the pores of WO3 NFs, that is applicable to high sensitivity breath sensors. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Size-dependent filtration of nanoparticles on porous films composed by polystyrene microsphere monolayers and applications in site-selective deposition of nanoparticles

International Nuclear Information System (INIS)

Ruan, Weidong; Zhou, Tieli; Sun, Chengbin; Tao, Yanchun; Lu, Fei; Wang, Xu; Zhao, Bing; Cui, Yinqiu

2015-01-01

Composite films composed of polystyrene (PS) microsphere monolayers and gold (Au) and/or silver (Ag) nanoparticles (NPs) decorations were prepared by a novel size-dependent filtration effect on close-packed PS microsphere arrays. The uniform pores inlaid in the PS monolayer films acted as the transport tunnels for NPs. The steric restriction induced by the size of the pores was used as a main strategy to fabricate hybrid micro/nano films, which were composed of PS microspheres with inhomogeneous anisotropic decorations. The Au and Ag NPs were used as the building blocks to decorate the PS microspheres through a layer-by-layer self-assembly technique with the aid of polyelectrolyte coupling agents. Only the small particles which could pass through the micropores could reach to and deposit on the inner surfaces of the PS microsphere monolayer films. Large particles remained on the outside and could only deposit on the outer surfaces. Thus, the inhomogeneous anisotropic decoration was obtained. This study provides a novel strategy for fabricating anisotropic micro/nanostructures by the size-dependent filtration effect of NPs on porous films and has the potential in applications of anisotropic self-assembly, sensor, and surface modifications at nanoscale.

Size-dependent filtration of nanoparticles on porous films composed by polystyrene microsphere monolayers and applications in site-selective deposition of nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Ruan, Weidong [Jilin University, State Key Laboratory of Supramolecular Structure and Materials (China); Zhou, Tieli [Changchun University, College of Food Engineering and Landscape Architecture (China); Sun, Chengbin; Tao, Yanchun; Lu, Fei; Wang, Xu; Zhao, Bing, E-mail: zhaob@mail.jlu.edu.cn [Jilin University, State Key Laboratory of Supramolecular Structure and Materials (China); Cui, Yinqiu, E-mail: cuiyq@jlu.edu.cn [Jilin University, School of Life Sciences (China)

2015-10-15

Composite films composed of polystyrene (PS) microsphere monolayers and gold (Au) and/or silver (Ag) nanoparticles (NPs) decorations were prepared by a novel size-dependent filtration effect on close-packed PS microsphere arrays. The uniform pores inlaid in the PS monolayer films acted as the transport tunnels for NPs. The steric restriction induced by the size of the pores was used as a main strategy to fabricate hybrid micro/nano films, which were composed of PS microspheres with inhomogeneous anisotropic decorations. The Au and Ag NPs were used as the building blocks to decorate the PS microspheres through a layer-by-layer self-assembly technique with the aid of polyelectrolyte coupling agents. Only the small particles which could pass through the micropores could reach to and deposit on the inner surfaces of the PS microsphere monolayer films. Large particles remained on the outside and could only deposit on the outer surfaces. Thus, the inhomogeneous anisotropic decoration was obtained. This study provides a novel strategy for fabricating anisotropic micro/nanostructures by the size-dependent filtration effect of NPs on porous films and has the potential in applications of anisotropic self-assembly, sensor, and surface modifications at nanoscale.

Modeling polydispersive ensembles of diamond nanoparticles

International Nuclear Information System (INIS)

Barnard, Amanda S

2013-01-01

While significant progress has been made toward production of monodispersed samples of a variety of nanoparticles, in cases such as diamond nanoparticles (nanodiamonds) a significant degree of polydispersivity persists, so scaling-up of laboratory applications to industrial levels has its challenges. In many cases, however, monodispersivity is not essential for reliable application, provided that the inevitable uncertainties are just as predictable as the functional properties. As computational methods of materials design are becoming more widespread, there is a growing need for robust methods for modeling ensembles of nanoparticles, that capture the structural complexity characteristic of real specimens. In this paper we present a simple statistical approach to modeling of ensembles of nanoparticles, and apply it to nanodiamond, based on sets of individual simulations that have been carefully selected to describe specific structural sources that are responsible for scattering of fundamental properties, and that are typically difficult to eliminate experimentally. For the purposes of demonstration we show how scattering in the Fermi energy and the electronic band gap are related to different structural variations (sources), and how these results can be combined strategically to yield statistically significant predictions of the properties of an entire ensemble of nanodiamonds, rather than merely one individual ‘model’ particle or a non-representative sub-set. (paper)

Morphologically and size uniform monodisperse particles and their shape-directed self-assembly

Energy Technology Data Exchange (ETDEWEB)

Collins, Joshua E.; Bell, Howard Y.; Ye, Xingchen; Murray, Christopher Bruce

2017-09-12

Monodisperse particles having: a single pure crystalline phase of a rare earth-containing lattice, a uniform three-dimensional size, and a uniform polyhedral morphology are disclosed. Due to their uniform size and shape, the monodisperse particles self assemble into superlattices. The particles may be luminescent particles such as down-converting phosphor particles and up-converting phosphors. The monodisperse particles of the invention have a rare earth-containing lattice which in one embodiment may be an yttrium-containing lattice or in another may be a lanthanide-containing lattice. The monodisperse particles may have different optical properties based on their composition, their size, and/or their morphology (or shape). Also disclosed is a combination of at least two types of monodisperse particles, where each type is a plurality of monodisperse particles having a single pure crystalline phase of a rare earth-containing lattice, a uniform three-dimensional size, and a uniform polyhedral morphology; and where the types of monodisperse particles differ from one another by composition, by size, or by morphology. In a preferred embodiment, the types of monodisperse particles have the same composition but different morphologies. Methods of making and methods of using the monodisperse particles are disclosed.

Green synthesis of monodisperse silver nanoparticles using hydroxy propyl methyl cellulose

Energy Technology Data Exchange (ETDEWEB)

Dong, Chunfa; Zhang, Xianglin, E-mail: hust_zxl@mail.hust.edu.cn; Cai, Hao

2014-01-15

Graphical abstract: -- Highlights: • Synthesis of silver nanoparticles using hydroxy propyl methyl cellulose is reported. • HPMC and glucose are used as capping agent and reducing agent respectively. • It is the first time to use HPMC for synthesis of silver nanoparticles. • The small, spherical and well-dispersed particle is observed in the range of 3–17 nm. • The green method can be extended to other noble metals. -- Abstract: A simple and environmentally friendly method for the synthesis of highly stable and small sized silver nanoparticles with narrow distribution from 3 nm to 17 nm is reported. Silver nitrate, hydroxy propyl methyl cellulose (HPMC) and glucose, were used as silver precursor, capping agents and reducing agents respectively. The formation of silver nanoparticles was observed by change of color from colorless to wine red. The silver nanoparticles were characterized by transmission electron microscopy (TEM), UV–visible spectroscopy (UV–vis), X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR). The results demonstrated that the obtained metallic nanoparticles were single crystalline silver nanoparticles capped with HPMC. The effects of the reaction time, reaction temperature and the concentration of silver ion and reducing agents on the particle size were investigated. A possible formation mechanism was proposed. The method may be extended to other noble metal for other technological applications such as additional medicinal, industrial applications.

Green synthesis of monodisperse silver nanoparticles using hydroxy propyl methyl cellulose

International Nuclear Information System (INIS)

Dong, Chunfa; Zhang, Xianglin; Cai, Hao

2014-01-01

Graphical abstract: -- Highlights: • Synthesis of silver nanoparticles using hydroxy propyl methyl cellulose is reported. • HPMC and glucose are used as capping agent and reducing agent respectively. • It is the first time to use HPMC for synthesis of silver nanoparticles. • The small, spherical and well-dispersed particle is observed in the range of 3–17 nm. • The green method can be extended to other noble metals. -- Abstract: A simple and environmentally friendly method for the synthesis of highly stable and small sized silver nanoparticles with narrow distribution from 3 nm to 17 nm is reported. Silver nitrate, hydroxy propyl methyl cellulose (HPMC) and glucose, were used as silver precursor, capping agents and reducing agents respectively. The formation of silver nanoparticles was observed by change of color from colorless to wine red. The silver nanoparticles were characterized by transmission electron microscopy (TEM), UV–visible spectroscopy (UV–vis), X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR). The results demonstrated that the obtained metallic nanoparticles were single crystalline silver nanoparticles capped with HPMC. The effects of the reaction time, reaction temperature and the concentration of silver ion and reducing agents on the particle size were investigated. A possible formation mechanism was proposed. The method may be extended to other noble metal for other technological applications such as additional medicinal, industrial applications

Study on magnetite nanoparticles synthesized by chemical method

International Nuclear Information System (INIS)

Pei Wenli; Kumada, H.; Natusme, T.; Saito, H.; Ishio, S.

2007-01-01

Magnetite nanoparticles with controlled size were synthesized by chemical method. Higher deposition temperature and a rapid-raising temperature procedure are favorable to particle size distribution and fabrication of monodisperse nanoparticles. The larger nanoparticles can be synthesized by the two-step method. The large nanoparticle (up to 25 nm) without agglomeration was successfully produced. The saturation magnetization of 11 nm magnetite particles was 45 emu/g at room temperature, which is smaller than that of bulk magnetite due to surface effect. Hysteresis of the magnetite nanoparticle was very small, indicating superparamagnetic behavior. The magnetic domains of the 11 nm magnetite nanoparticles were successfully observed by MFM

Antifungal activity of gold nanoparticles prepared by solvothermal method

Energy Technology Data Exchange (ETDEWEB)

Ahmad, Tokeer, E-mail: tahmad3@jmi.ac.in [Nanochemistry Laboratory, Department of Chemistry, Jamia Millia Islamia, New Delhi 110025 (India); Wani, Irshad A.; Lone, Irfan H.; Ganguly, Aparna [Nanochemistry Laboratory, Department of Chemistry, Jamia Millia Islamia, New Delhi 110025 (India); Manzoor, Nikhat; Ahmad, Aijaz [Department of Biosciences, Jamia Millia Islamia, New Delhi 110025 (India); Ahmed, Jahangeer [Department of Chemistry, Michigan State University, East Lansing, MI 48824 (United States); Al-Shihri, Ayed S. [Department of Chemistry, Faculty of Science, King Khalid University, Abha 61413, P.O. Box 9004 (Saudi Arabia)

2013-01-15

Graphical abstract: Gold nanoparticles (7 and 15 nm) of very high surface area (329 and 269 m{sup 2}/g) have been successfully synthesized through solvothermal method by using tin chloride and sodium borohydride as reducing agents. As-prepared gold nanoparticles shows very excellent antifungal activity against Candida isolates and activity increases with decrease in the particle size. Display Omitted Highlights: ► Effect of reducing agents on the morphology of gold nanoparticles. ► Highly uniform and monodisperse gold nanoparticles (7 nm). ► Highest surface area of gold nanoparticles (329 m{sup 2/}g). ► Excellent antifungal activity of gold nanoparticles against Candida strains. -- Abstract: Gold nanoparticles have been successfully synthesized by solvothermal method using SnCl{sub 2} and NaBH{sub 4} as reducing agents. X-ray diffraction studies show highly crystalline and monophasic nature of the gold nanoparticles with face centred cubic structure. The transmission electron microscopic studies show the formation of nearly spherical gold nanoparticles of average size of 15 nm using SnCl{sub 2}, however, NaBH{sub 4} produced highly uniform, monodispersed and spherical gold nanoparticles of average grain size of 7 nm. A high surface area of 329 m{sup 2}/g for 7 nm and 269 m{sup 2}/g for 15 nm gold nanoparticles was observed. UV–vis studies assert the excitations over the visible region due to transverse and longitudinal surface plasmon modes. The gold nanoparticles exhibit excellent size dependant antifungal activity and greater biocidal action against Candida isolates for 7 nm sized gold nanoparticles restricting the transmembrane H{sup +} efflux of the Candida species than 15 nm sized gold nanoparticles.

Antifungal activity of gold nanoparticles prepared by solvothermal method

International Nuclear Information System (INIS)

Ahmad, Tokeer; Wani, Irshad A.; Lone, Irfan H.; Ganguly, Aparna; Manzoor, Nikhat; Ahmad, Aijaz; Ahmed, Jahangeer; Al-Shihri, Ayed S.

2013-01-01

Graphical abstract: Gold nanoparticles (7 and 15 nm) of very high surface area (329 and 269 m 2 /g) have been successfully synthesized through solvothermal method by using tin chloride and sodium borohydride as reducing agents. As-prepared gold nanoparticles shows very excellent antifungal activity against Candida isolates and activity increases with decrease in the particle size. Display Omitted Highlights: ► Effect of reducing agents on the morphology of gold nanoparticles. ► Highly uniform and monodisperse gold nanoparticles (7 nm). ► Highest surface area of gold nanoparticles (329 m 2/ g). ► Excellent antifungal activity of gold nanoparticles against Candida strains. -- Abstract: Gold nanoparticles have been successfully synthesized by solvothermal method using SnCl 2 and NaBH 4 as reducing agents. X-ray diffraction studies show highly crystalline and monophasic nature of the gold nanoparticles with face centred cubic structure. The transmission electron microscopic studies show the formation of nearly spherical gold nanoparticles of average size of 15 nm using SnCl 2 , however, NaBH 4 produced highly uniform, monodispersed and spherical gold nanoparticles of average grain size of 7 nm. A high surface area of 329 m 2 /g for 7 nm and 269 m 2 /g for 15 nm gold nanoparticles was observed. UV–vis studies assert the excitations over the visible region due to transverse and longitudinal surface plasmon modes. The gold nanoparticles exhibit excellent size dependant antifungal activity and greater biocidal action against Candida isolates for 7 nm sized gold nanoparticles restricting the transmembrane H + efflux of the Candida species than 15 nm sized gold nanoparticles.

Converting homogeneous to heterogeneous in electrophilic catalysis using monodisperse metal nanoparticles.

Science.gov (United States)

Witham, Cole A; Huang, Wenyu; Tsung, Chia-Kuang; Kuhn, John N; Somorjai, Gabor A; Toste, F Dean

2010-01-01

A continuing goal in catalysis is to unite the advantages of homogeneous and heterogeneous catalytic processes. To this end, nanoparticles represent a new frontier in heterogeneous catalysis, where this unification can also be supplemented by the ability to obtain new or divergent reactivity and selectivity. We report a novel method for applying heterogeneous catalysts to known homogeneous catalytic reactions through the design and synthesis of electrophilic platinum nanoparticles. These nanoparticles are selectively oxidized by the hypervalent iodine species PhICl(2), and catalyse a range of π-bond activation reactions previously only catalysed through homogeneous processes. Multiple experimental methods are used to unambiguously verify the heterogeneity of the catalytic process. The discovery of treatments for nanoparticles that induce the desired homogeneous catalytic activity should lead to the further development of reactions previously inaccessible in heterogeneous catalysis. Furthermore, a size and capping agent study revealed that Pt PAMAM dendrimer-capped nanoparticles demonstrate superior activity and recyclability compared with larger, polymer-capped analogues.

Converting Homogeneous to Heterogeneous in Electrophilic Catalysis using Monodisperse Metal Nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Witham, Cole A.; Huang, Wenyu; Tsung, Chia-Kuang; Kuhn, John N.; Somorjai, Gabor A.; Toste, F. Dean

2009-10-15

A continuing goal in catalysis is the transformation of processes from homogeneous to heterogeneous. To this end, nanoparticles represent a new frontier in heterogeneous catalysis, where this conversion is supplemented by the ability to obtain new or divergent reactivity and selectivity. We report a novel method for applying heterogeneous catalysts to known homogeneous catalytic reactions through the design and synthesis of electrophilic platinum nanoparticles. These nanoparticles are selectively oxidized by the hypervalent iodine species PhICl{sub 2}, and catalyze a range of {pi}-bond activation reactions previously only homogeneously catalyzed. Multiple experimental methods are utilized to unambiguously verify the heterogeneity of the catalytic process. The discovery of treatments for nanoparticles that induce the desired homogeneous catalytic activity should lead to the further development of reactions previously inaccessible in heterogeneous catalysis. Furthermore, our size and capping agent study revealed that Pt PAMAM dendrimer-capped nanoparticles demonstrate superior activity and recyclability compared to larger, polymer-capped analogues.

Molecular modeling and simulation of atactic polystyrene/amorphous silica nanocomposites

International Nuclear Information System (INIS)

Mathioudakis, I; Vogiatzis, G G; Tzoumanekas, C; Theodorou, D N

2016-01-01

The local structure, segmental dynamics, topological analysis of entanglement networks and mechanical properties of atactic polystyrene - amorphous silica nanocomposites are studied via molecular simulations using two interconnected levels of representation: (a) A coarse - grained level. Equilibration at all length scales at this level is achieved via connectivity - altering Monte Carlo simulations. (b) An atomistic level. Initial configurations for atomistic Molecular Dynamics (MD) simulations are obtained by reverse mapping well- equilibrated coarse-grained configurations. By analyzing atomistic MD trajectories, the polymer density profile is found to exhibit layering in the vicinity of the nanoparticle surface. The dynamics of polystyrene (in neat and filled melt systems) is characterized in terms of bond orientation. Well-equilibrated coarse-grained long-chain configurations are reduced to entanglement networks via topological analysis with the CReTA algorithm. Atomistic simulation results for the mechanical properties are compared to the experimental measurements and other computational works. (paper)

Polystyrene/magnetite nanocomposite synthesis and characterization: investigation of magnetic and electrical properties for using as microelectromechanical systems (MEMS

Directory of Open Access Journals (Sweden)

Omidi Mohammad Hassan

2017-02-01

Full Text Available In this work, a novel polystyrene/Fe3O4 nanocomposite prepared by in-situ method is presented. Magnetic Fe3O4 nanoparticles were encapsulated by polystyrene. The FT-IR spectra confirmed polystyrene/Fe3O4 nanocomposite preparation. The electrical properties of prepared nanocomposite were investigated by cyclic voltammetry (CV. The CV analysis showed good electrical conductivity of the synthesized nanocomposite. Magnetic properties of the nanocomposite were studied by vibrating sample magnetometer (VSM. The VSM analysis confirmed magnetic properties of the nanocomposite. The morphology and the size of the synthesized nanocomposite were investigated by field emission scanning electron microscope (FESEM. According to the VSM and CV results, such nanocomposite can be used in microelectromechanical systems.

Bulk synthesis of monodisperse magnetic FeNi3 nanopowders by flow levitation method.

Science.gov (United States)

Chen, Shanjun; Chen, Yan; Kang, Xiaoli; Li, Song; Tian, Yonghong; Wu, Weidong; Tang, Yongjian

2013-10-01

In this work, a novel bulk synthesis method for monodisperse FeNi3 nanoparticles was developed by flow levitation method (FL). The Fe and Ni vapours ascending from the high temperature levitated droplet was condensed by cryogenic Ar gas under atmospheric pressure. X-ray diffraction was used to identify and characterize the crystal phase of prepared powders exhibiting a FeNi3 phase. The morphology and size of nanopowders were observed by transmission electron microscopy (TEM). The chemical composition of the nanoparticles was determined with energy dispersive spectrometer (EDS). The results indicated that the FeNi3 permalloy powders are nearly spherical-shaped with diameter about 50-200 nm. Measurement of the magnetic property of nanopowders by a superconducting quantum interference device (SQUID, Quantum Design MPMS-7) showed a symmetric hysteresis loop of ferromagnetic behavior with coercivity of 220 Oe and saturation magnetization of 107.17 emu/g, at 293 K. At 5 K, the obtained saturation magnetization of the sample was 102.16 emu/g. The production rate of FeNi3 nanoparticles was estimated to be about 6 g/h. This method has great potential in mass production of FeNi3 nannoparticles.

Development of new ionic gelation strategy: Towards the preparation of new monodisperse and stable hyaluronic acid/β-cyclodextrin-grafted chitosan nanoparticles as drug delivery carriers for doxorubicin

Science.gov (United States)

Mihoub, Amina Ben; Saidat, Boubakeur; Bal, Youssef; Frochot, Céline; Vanderesse, Régis; Acherar, Samir

2018-03-01

In the present study, β-cyclodextrin-grafted chitosan nanoparticles (β-CD- g-CS NPs) were prepared using a new ionic gelation strategy involving a synergistic effect of NaCl (150 mmol/L), 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES, 10 mmol/L), and water bath sonication. This new strategy afforded smaller and more monodisperse β-CD- g-CS NPs vs. the classical ionic gelation method. New HA/β-CD- g-CS NPs were also prepared using the above-mentioned strategy by adding hyaluronic acid (HA) to the β-CD- g-CS copolymer at different weight ratios until the ZP values conversion. The best result was obtained with the weight ratio of w(HA): w(β-CD- g-CS) = 2:1 and furnished new spherical and smooth HA/β-CD- g-CS NPs. Furthermore, the stability of β- CD- g-CS NPs and HA/β-CD- g-CS NPs at 4°C in physiological medium (pH 7.4) was compared for 3 weeks period and showed that HA/β-CD- g-CS NPs were more stable all maintaining their monodispersity and high negative ZP values compared to β-CD- g-CS NPs. Finally, preliminary study of HA/β-CD- g-CS NPs as carrier for the controlled release of the anticancer drug doxorubicin was investigated. These new HA/β-CD- g-CS NPs can potentially be used as drug delivery and targeting systems for cancer treatment.

Physical and Chemical Changes of Polystyrene Nanospheres Irradiated with Laser

International Nuclear Information System (INIS)

Mustafa, Mohd Ubaidillah; Juremi, Nor Rashidah Md.; Mohamad, Farizan; Wibawa, Pratama Jujur; Agam, Mohd Arif; Ali, Ahmad Hadi

2011-01-01

It has been reported that polymer resist such as PMMA (Poly(methyl methacrylate) which is a well known and commonly used polymer resist for fabrication of electronic devices can show zwitter characteristic due to over exposure to electron beam radiation. Overexposed PMMA tend to changes their molecular structure to either become negative or positive resist corresponded to electron beam irradiation doses. These characteristic was due to crosslinking and scissors of the PMMA molecular structures, but till now the understanding of crosslinking and scissors of the polymer resist molecular structure due to electron beam exposure were still unknown to researchers. Previously we have over exposed polystyrene nanospheres to various radiation sources, such as electron beam, solar radiation and laser, which is another compound that can act as polymer resist. We investigated the physical and chemical structures of the irradiated polystyrene nanospheres with FTIR analysis. It is found that the physical and chemical changes of the irradiated polystyrene were found to be corresponded with the radiation dosages. Later, combining Laser irradiation and Reactive Ion Etching manipulation, created a facile technique that we called as LARIEA NSL (Laser and Reactive Ion Etching Assisted Nanosphere Lithography) which can be a facile technique to fabricate controllable carbonaceous nanoparticles for applications such as lithographic mask, catalysts and heavy metal absorbers.

Characterization of the oleic acid/iron oxide nanoparticle interface by magnetic resonance

Energy Technology Data Exchange (ETDEWEB)

Masur, S., E-mail: sabrina.masur@uni-due.de; Zingsem, B.; Marzi, T.; Meckenstock, R.; Farle, M.

2016-10-01

The synthesis of colloidal nanoparticles involves surfactant molecules, which bind to the particle surface and stabilize nanoparticles against aggregation. In many cases these protecting shells also can be used for further functionalization. In this study, we investigated monodisperse single crystalline iron oxide core/shell nanoparticles (Fe{sub x}O{sub y}-NPs) in situ covered with an oleic acid layer which showed two electron spin resonance (ESR) signals. The nanoparticles with the ligands attached were characterized by transmission electron microscopy (TEM) and ferro- and paramagnetic resonance (FMR, EPR). Infrared spectroscopy confirmed the presence of the functional groups and revealed that the oleic acid (OA) is chemisorbed as a carboxylate on the iron oxide and is coordinated symmetrically to the oxide atoms. We show that the EPR signal of the OA ligand molecule can be used as a local probe to determine the temperature changes at the surface of the nanoparticle. - Highlights: • Monodisperse single crystalline iron oxide core/shell nanoparticles (Fe{sub x}O{sub y}-NPs) in situ covered with an oleic acid layer two electron spin resonance (ESR) signals. • We show that the EPR signal of the OA ligand molecule can be used as a local probe to determine the temperature changes at the surface of the nanoparticle.

Fabrication of Sesame Sticks-like Silver Nanoparticles/Polystyrene Hybridnanotubes and Their Catalytic Effects.

Science.gov (United States)

Peng, Fang; Wang, Qi; Shi, Rongjia; Wang, Zeyi; You, Xin; Liu, Yuhong; Wang, Fenghe; Gao, Jay; Mao, Chun

2016-12-21

A novel and efficient catalyst is one of the goals in the material field, and the involvement of nanoscience and technology has brought new vigor to the development of catalyst. This research aimed to develop a simple two-step route to fabricate Fe 3 O 4 @PS/PDA-Ag hybridnanotubes with size-controllable and highly dispersed silver nanoparticles (NPs). First, Fe 3 O 4 @PS nanotubes of a sound mechanical property were prepared using polystyrene (PS)/toluene solution containing highly dispersed oleic acid modified Fe 3 O 4 particles in a commercial AAO template. Next, the facile technique was used to form in situ silver NPs on the surface of magnetic PS (Fe 3 O 4 @PS) nanotubes through dopamine coating. The catalytic effects of the prepared Fe 3 O 4 @PS/PDA-Ag hybridnanotubes with highly dispersed AgNPs were characterized using a range of analytical methods, including transmission electron microscopy, thermogravimetric analysis, UV-Visible spectroscopy, and X-ray diffraction. It was found that such prepared Fe 3 O 4 @PS/PDA-Ag hybridnanotubes had a large specific surface area. They possessed excellent activities in catalyzing the reduction of 4-nitrophenol (4-NP) by NaBH 4 in the aqueous phase. Furthermore, they were readily separated from fluid and retrieved by an external magnet. Their catalyst activity and recyclability demonstrated that this approach we proposed had the potential to become a new idea and route for catalytic platform.

Nanoparticle Encapsulation in Diblock Copolymer/Homopolymer Blend Thin Film Mixtures

Science.gov (United States)

Zhao, Junnan; Chen, Xi; Green, Peter

2014-03-01

We investigated the organization of low concentrations of poly (2-vinylpyridine) (P2VP) grafted gold nanoparticles within a diblock copolymer polystyrene-b-poly (2-vinylpyridine) (PS-b-P2VP)/homopolymer polystyrene (PS) blend thin film. The PS-b-P2VP copolymers formed micelles, composed of inner cores of P2VP block and outer coronae of PS blocks, throughout the homopolymer PS. All nanoparticles were encapsulated within micelle cores and each micelle contained one or no nanoparticle, on average. When the host PS chains are much longer than corona chains, micelles tended to self-organize at the interfaces. Otherwise, they were dispersed throughout the PS host. In comparison to the neat PS-b-P2VP/PS blend, the nanoparticles/PS-b-P2VP/PS system had a higher density of smaller micelles, influenced largely by the number of nanoparticles in the system. The behavior of this system is understood in terms of the maximization of the nanoparticle/micelle core interactions and of the translational entropies of the micelles and the nanoparticles.

Nanogel-quantum dot hybrid nanoparticles for live cell imaging

International Nuclear Information System (INIS)

Hasegawa, Urara; Nomura, Shin-ichiro M.; Kaul, Sunil C.; Hirano, Takashi; Akiyoshi, Kazunari

2005-01-01

We report here a novel carrier of quantum dots (QDs) for intracellular labeling. Monodisperse hybrid nanoparticles (38 nm in diameter) of QDs were prepared by simple mixing with nanogels of cholesterol-bearing pullulan (CHP) modified with amino groups (CHPNH 2 ). The CHPNH 2 -QD nanoparticles were effectively internalized into the various human cells examined. The efficiency of cellular uptake was much higher than that of a conventional carrier, cationic liposome. These hybrid nanoparticles could be a promising fluorescent probe for bioimaging

Size-controlled synthesis of nickel nanoparticles

International Nuclear Information System (INIS)

Hou, Y.; Kondoh, H.; Ohta, T.; Gao, S.

2005-01-01

A facile reduction approach with nickel acetylacetonate, Ni(acac) 2 , and sodium borohydride or superhydride leads to monodisperse nickel nanoparticles in the presence of hexadecylamine (HDA) and trioctylphosphine oxide (TOPO). The combination of HDA and TOPO used in the conventional synthesis of semiconductor nanocrystals also provides better control over particle growth in the metal nanoparticle synthesis. The size of Ni nanoparticles can be readily tuned from 3 to 11 nm, depending on the ratio of HDA to TOPO in the reaction system. As-synthesized Ni nanoparticles have a cubic structure as characterized by power X-ray diffraction (XRD), selected-area electron diffraction (SAED). Transmission electron microscopy (TEM) images show that Ni nanoparticles have narrow size distribution. SQUID magnetometry was also used in the characterization of Ni nanoparticles. The synthetic procedure can be extended to the preparation of high quality metal or alloy nanoparticles

Digestive ripening facilitated atomic diffusion at nanosize regime: Case of AuIn{sub 2} and Ag{sub 3}In intermetallic nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Arora, Neha [Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560 012 (India); Jagirdar, Balaji R., E-mail: jagirdar@ipc.iisc.ernet.in [Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560 012 (India); Klabunde, Kenneth J. [Department of Chemistry, Kansas State University, Manhattan, KS 66506 (United States)

2014-10-15

Highlights: • A digestive ripening facilitated interatomic diffusion process is presented. • Nearly monodisperse AuIn{sub 2} and Ag{sub 3}In intermetallic nanoparticles were synthesized. • Optimization of reaction temperature facilitates interatomic transfer. • Presence of excess ligand plays a crucial role in the digestive ripening process. - Abstract: Monodisperse colloidal gold–indium (AuIn{sub 2}) intermetallic nanoparticles have been synthesized from Au and In colloids using the digestive ripening process. Formation of the intermetallic proceeds via digestive ripening facilitated atomic diffusion of Au and In atoms from the Au and In nanoparticles followed simultaneously by their growth in the solution. Optimization of the reaction temperature was found to be crucial for the formation of AuIn{sub 2} intermetallic from gold and indium nanoparticles. Transmission electron microscopy revealed the presence of nearly monodisperse nanoparticles of Au and AuIn{sub 2} with particle size distribution of 3.7 ± 1.0 nm and 5.0 ± 1.6 nm, respectively. UV–visible spectral studies brought out the absence of SPR band in pure AuIn{sub 2} intermetallic nanoparticles. Optical study and electron microscopy, in combination with powder X-ray diffraction established phase pure AuIn{sub 2} intermetallic nanoparticles unambiguously. The potential of such an unprecedented approach has been further exploited in the synthesis of Ag{sub 3}In intermetallic nanoparticles with the dimension of less than 10 nm.

Monodispersed porous flowerlike PtAu nanocrystals as effective electrocatalysts for ethanol oxidation

Science.gov (United States)

Li, Shumin; Xu, Hui; Xiong, Zhiping; Zhang, Ke; Wang, Caiqin; Yan, Bo; Guo, Jun; Du, Yukou

2017-11-01

Designing and tuning the bimetallic nanoparticles with desirable morphology and structure can embody them with greatly enhanced electrocatalytic activity and stability towards liquid fuel oxidation. We herein reported a facile one-pot method for the controlled synthesis of monodispersed binary PtAu nanoflowers with abundant exposed surface area. Owing to its fantastic structure, synergistic and electronic effect, such as-prepared PtAu nanoflowers exhibited outstandingly high electrocatalytic activity with the mass activity of 6482 mA mg-1 towards ethanol oxidation, which is 28.3 times higher than that of commercial Pt/C (227 mA mg-1). More interesting, the present PtAu nanoflower catalysts are more stable for the ethanol oxidation reaction in the alkaline with lower current density decay and retained a much higher current density after successive CVs of 500 cycles than that of commercial Pt/C. This work may open a new way for maximizing the catalytic performance of electrocatalysts towards ethanol oxidation by synthesizing shape-controlled alloy nanoparticles with more surface active sites to enhance the performances of direct fuel cells reaction, chemical conversion, and beyond.

Rapid Synthesis of Highly Monodisperse Au x Ag 1− x Alloy Nanoparticles via a Half-Seeding Approach

KAUST Repository

Chng, Ting Ting; Polavarapu, Lakshminarayana; Xu, Qing Hua; Ji, Wei; Zeng, Hua Chun

2011-01-01

Gold-silver alloy AuxAg1-x is an important class of functional materials promising new applications across a wide array of technological fields. In this paper, we report a fast and facile synthetic protocol for preparation of highly monodisperse Aux

Fabrication of color changeable polystyrene spheres decorated by gold nanoparticles and their label-free biosensing

Energy Technology Data Exchange (ETDEWEB)

Xia Yuetong; Lu Wensheng; Jiang Long, E-mail: jiangl@iccas.ac.cn [Beijing National Laboratory for Molecular Science, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)

2010-02-26

A novel and simple method for gold nanoshell synthesis with controllable core and shell sizes is reported here. A new 'tree-shape' surfactant bis(amidoethyl-carbamoylethyl) octadecylamine (C18N3) was synthesized and used as the glue for the fast combination of gold nanoparticles and the subsequent gold shell outside. The functionalized polystyrene (PS) cores were covered by a surfactant (PS-C18N3) bilayer. The presence of the surfactant double layer played the role of 'glue' in this method, so that upon controlling the amount of surfactant, it was possible to achieve: the manipulation of gold seed density on the PS-C18N3 spheres, the preparation of PS-Au hybrid structures, and a red-shift in the extinction absorption from 520 to 750 nm. Besides, the as-prepared PS-Au composites supported on a glass substrate exhibited excellent effectiveness in the molecular recognition of human-immunoglobulin G (h-IgG) and goat anti-human-immunoglobulin G (goat anti-h-IgG), showing a rapid response within 20 min with a low detection limit of 10 ng ml{sup -1}. This demonstrates that PS-Au prepared and assembled using our method is potentially useful as a nanosensor platform for immunoassay.

Imaging and size measurement of nanoparticles in aqueous medium by use of atomic force microscopy.

Science.gov (United States)

Takechi-Haraya, Yuki; Goda, Yukihiro; Sakai-Kato, Kumiko

2018-02-01

Size control of nanoparticles in nanotechnology-based drug products is crucial for their successful development, since the in vivo pharmacokinetics of nanoparticles are size-dependent. In this study, we evaluated the use of atomic force microscopy (AFM) for imaging and size measurement of nanoparticles in aqueous medium. The height sizes of rigid polystyrene nanoparticles and soft liposomes were measured by AFM and were compared with the hydrodynamic sizes measured by dynamic light scattering (DLS). The lipid compositions of the studied liposomes were similar to those of commercial products. AFM proved to be a viable method for obtaining images of both polystyrene nanoparticles and liposomes in aqueous medium. For the polystyrene nanoparticles, the average height size observed by AFM was similar to the average number-weighted diameter obtained by DLS, indicating the usefulness of AFM for measuring the sizes of nanoparticles in aqueous medium. For the liposomes, the height sizes obtained by AFM differed depending upon the procedures of immobilizing the liposomes onto a solid substrate. In addition, the resultant average height sizes of the liposomes were smaller than those obtained by DLS. This knowledge will help the correct use of AFM as a powerful tool for imaging and size measurement of nanotechnology-based drug products for clinical use.

Straightforward and robust synthesis of monodisperse surface-functionalized gold nanoclusters

Directory of Open Access Journals (Sweden)

Silvia Varela-Aramburu

2016-09-01

Full Text Available Gold nanoclusters are small (1–3 nm nanoparticles with a high surface area that are useful for biomedical studies and drug delivery. The synthesis of small, surface-functionalized gold nanoclusters is greatly dependent on the reaction conditions. Here, we describe a straightforward, efficient and robust room temperature one-pot synthesis of 2 nm gold nanoclusters using thioglucose as a reducing and stabilizing agent, which was discovered by serendipity. The resultant monodisperse gold nanoclusters are more stable than those generated using some other common methods. The carboxylic acid contained in the stabilizing agent on the cluster surface serves as anchor for nanocluster functionalization. Alternatively, the addition of thiols serves to functionalize the nanoclusters. The resulting non-cytotoxic nanoclusters are taken up by cells and constitute a tuneable platform for biomedical applications including drug delivery.

EFFECT OF INCORPORATING EXPANDED POLYSTYRENE ...

African Journals Online (AJOL)

2012-11-03

Nov 3, 2012 ... Incorporating expanded polystyrene granules in concrete matrix can produce lightweight polystyrene aggregate concrete of ... structure. [1] reported that the standard workability tests are not suitable for the polystyrene aggregate concrete since they are sensitive to the unit weight of concrete. [2] made ...

Preparation and thermodynamic stability of micron-sized, monodisperse composite polymer particles of disc-like shapes by seeded dispersion polymerization.

Science.gov (United States)

Fujibayashi, Teruhisa; Okubo, Masayoshi

2007-07-17

Micron-sized, monodisperse composite polymer particles having "disc-like" and "polyhedral" shapes were prepared by seeded dispersion polymerization of 2-ethylhexylmethacrylate (EHMA) with 2.67-mum-sized polystyrene (PS) seed particles in methanol/water media in the presence of droplets of various saturated hydrocarbons and evaporation of the hydrocarbon after the polymerization. Such nonspherical shapes were based on the volume reduction due to the evaporation. The primary factors influencing the particle shape seemed to be the absorption rate of the hydrocarbon into the resulting PS/poly(EHMA)/hydrocarbon composite particles during the polymerization, which affected the viscosities and the volumes of the PS and poly(EHMA) phases. It was found that the morphological development during the polymerization was retarded at "hamburger-like" morphology, which is a precursor of the disc-like particle, although this morphology is a thermodynamically metastable state.

The Generation And Properties Of Solid Monodisperse Aerosols Of ...

African Journals Online (AJOL)

A monodisperse aerosol generator (MAGE) was used to generate calibration or monodisperse aerosols containing stearic acid and carnauba wax. Some of the factors affecting the size of aerosol particles generated with the MAGE were determined. The factors include: temperature of operation of the MAGE, type and purity ...

Improved performances of 36 m small-angle neutron scattering spectrometer BATAN in Serpong Indonesia

International Nuclear Information System (INIS)

Putra, Edy Giri Rachman; Bharoto; Santoso, Eddy; Ikram, Abarrul

2009-01-01

SMARTer, a 36 m small-angle neutron scattering (SANS) spectrometer owned by the National Nuclear Energy Agency of Indonesia (BATAN) was installed at the Neutron Scattering Laboratory (NSL) in Serpong, Indonesia. Lots of works on replacing, upgrading and improving the control system, experimental methods, data collection and reduction in the last two years have been carried out to optimize the performance of SMARTer. Some standard samples such as silver behenate, monodisperse polystyrene nanoparticle, porous silica and block copolymer PS-PEP film were measured for the inter-laboratory comparison.

Water-Soluble N-Heterocyclic Carbene-Protected Gold Nanoparticles: Size-Controlled Synthesis, Stability, and Optical Properties

OpenAIRE

Salorinne, Kirsi; Man, Renee W.Y.; Li, Chien-Hung; Taki, Masayasu; Nambo, Masakazu; Crudden, Cathleen M.

2017-01-01

NHC-Au(I) complexes were used to prepare stable, water-soluble, NHC-protected gold nanoparticles. The water-soluble, charged nature of the nanoparticles permitted analysis by polyacrylamide gel electrophoresis (PAGE), which showed that the nanoparticles were highly monodisperse, with tunable core diameters between 2.0 and 3.3 nm depending on the synthesis conditions. Temporal, thermal, and chemical stability of the nanoparticles were determined to be high. Treatment with thiols caused etching...

Size Controlled Synthesis of Starch Nanoparticles by a Microemulsion Method

Directory of Open Access Journals (Sweden)

Suk Fun Chin

2014-01-01

Full Text Available Controllable particles sizes of starch nanoparticles were synthesized via a precipitation in water-in-oil microemulsion approach. Microemulsion method offers the advantages of ultralow interfacial tension, large interfacial area, and being thermodynamically stable and affords monodispersed nanoparticles. The synthesis parameters such as stirring rates, ratios of oil/cosurfactant, oil phases, cosurfactants, and ratios of water/oil were found to affect the mean particle size of starch nanoparticles. Starch nanoparticles with mean particles sizes of 109 nm were synthesized by direct nanoprecipitation method, whereas by using precipitation in microemulsion approach, starch nanoparticles with smaller mean particles sizes of 83 nm were obtained.

Effect of serum proteins on polystyrene nanoparticle uptake and intracellular trafficking in endothelial cells

International Nuclear Information System (INIS)

Guarnieri, Daniela; Guaccio, Angela; Fusco, Sabato; Netti, Paolo A.

2011-01-01

The physico-chemical properties of nanoparticles (NPs), such as small dimensions, surface charge and surface functionalization, control their capability to interact with cells and, in particular, with sub-cellular components. This interaction can be also influenced by the adsorption of molecules present in biological fluids, like blood, on NP surface. Here, we analysed the effect of serum proteins on 49 and 100 nm red fluorescent polystyrene NP uptake in porcine aortic endothelial (PAE) cells, as a model for vascular transport. To this aim, NP uptake kinetic, endocytic pathway and intracellular trafficking were studied by monitoring NPs inside cells through confocal microscopy and multiple particle tracking (MPT). We demonstrated that NPs are rapidly internalized by cells in serum-free (SF) medium, according to a saturation kinetic. Conversely, in 10% foetal bovine serum-enriched (SE) medium, NP uptake rate results drastically reduced. Moreover, NP internalization depends on an active endocytic mechanism that does not involve clathrin- and caveolae-mediated vesicular transport, in both SE and SF media. Furthermore, MPT data indicate that NP intracellular trafficking is unaffected by protein presence. Indeed, approximately 50–60% of internalized NPs is characterized by a sub-diffusive behaviour, whereas the remaining fraction shows an active motion. These findings demonstrate that the unspecific protein adsorption on NP surface can affect cellular uptake in terms of internalization kinetics, but it is not effective in controlling active and cellular-mediated uptake mechanisms of NPs and their intracellular routes.

Polystyrene/magnesium hydroxide nanocomposite particles prepared by surface-initiated in-situ polymerization

International Nuclear Information System (INIS)

Liu Hui; Yi Jianhong

2009-01-01

In order to avoid their agglomeration and incompatibility with hydrophobic polystyrene substrate, magnesium hydroxide nanoparticles were encapsulated by surface-initiated in-situ polymerization of styrene. The process contained two steps: electrostatic adsorption of initiator and polymerization of monomer on the surface of magnesium hydroxide. It was found that high adsorption ratio in the electrostatic adsorption of initiator could be attained only in acidic region, and the adsorption belonged to typical physical process. Compared to traditional in-situ polymerization, higher grafting ratio was obtained in surface-initiated in-situ polymerization, which can be attributed to weaker steric hindrance. Both Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM) indicated that polystyrene/magnesium hydroxide nanocomposite particles had been successfully prepared by surface-initiated in-situ polymerization. The resulting samples were also analyzed and characterized by means of contact angle testing, dispersibility evaluation and thermogravimetric analysis

Biotemplate synthesis of monodispersed iron phosphate hollow microspheres

International Nuclear Information System (INIS)

Cao Feng; Li Dongxu

2010-01-01

Monodispersed iron phosphate hollow microspheres with a high degree of crystallization were prepared through a facile in situ deposition method using rape pollen grains as a biotemplate. The functional group on the surface of the pollen grains could adsorb Fe 3+ , which provided the nucleation sites for growth of iron phosphate nanoparticles. After being sintered at 600 deg. C for 10 h, the pollen grains were removed and iron phosphate hollow microspheres were obtained. A scanning electron microscope and x-ray diffraction were applied to characterize the morphology and crystalline structure of the pollen grains, iron phosphate-coated pollen grains and iron phosphate hollow microspheres. Differential scanning calorimetry and thermogravity analyses were performed to investigate the thermal behavior of the iron phosphate-coated pollen grains during the calcinations. Energy dispersive spectroscopy and Fourier transform infrared spectroscopy were utilized to investigate the interaction between the pollen grains and iron phosphate. The effect of the pollen wall on the surface morphology of these iron phosphate hollow microspheres was also proven in this work.

Biotemplate synthesis of monodispersed iron phosphate hollow microspheres

Energy Technology Data Exchange (ETDEWEB)

Cao Feng; Li Dongxu, E-mail: dongxuli@njut.edu.c [College of Materials Science and Engineering, Nanjing University of Technology, Jiangsu Nanjing 210009 (China)

2010-03-15

Monodispersed iron phosphate hollow microspheres with a high degree of crystallization were prepared through a facile in situ deposition method using rape pollen grains as a biotemplate. The functional group on the surface of the pollen grains could adsorb Fe{sup 3+}, which provided the nucleation sites for growth of iron phosphate nanoparticles. After being sintered at 600 deg. C for 10 h, the pollen grains were removed and iron phosphate hollow microspheres were obtained. A scanning electron microscope and x-ray diffraction were applied to characterize the morphology and crystalline structure of the pollen grains, iron phosphate-coated pollen grains and iron phosphate hollow microspheres. Differential scanning calorimetry and thermogravity analyses were performed to investigate the thermal behavior of the iron phosphate-coated pollen grains during the calcinations. Energy dispersive spectroscopy and Fourier transform infrared spectroscopy were utilized to investigate the interaction between the pollen grains and iron phosphate. The effect of the pollen wall on the surface morphology of these iron phosphate hollow microspheres was also proven in this work.

Spherical and polygonal shape of Au nanoparticles coated functionalized polymer microspheres

Energy Technology Data Exchange (ETDEWEB)

Xu, Ting; Li, Yingzhi; Zhang, Junxian; Qi, Yalong; Zhao, Xin; Zhang, Qinghua, E-mail: qhzhang@dhu.edu.cn

2015-08-01

Highlights: • PS/PPy with well-defined core/shell structures was prepared in aqueous solution. • Au NPs were coated on PS/PPy by the fixation and continuous growth process. • Mercapto-groups played a role in the number and morphology of Au shell. • PS/PPy/Au had homogeneous and dense Au coatings with different shape. - Abstract: Uniform polystyrene (PS)/polypyrrole (PPy) composite microspheres with well-defined core/shell structures are synthesized by chemical oxidative polymerization. Gold nanoparticles (Au NPs) are successfully coated on the surface of PS/PPy microspheres by means of electrostatic interactions due to the functionalized PPy coatings supplying sufficient amino groups and the additive of mercapto acetic acid. Furthermore, the as-prepared PS/PPy/Au microspheres serving as seeds facilitate Au NPs further growth by in situ reduction in HAuCl{sub 4} solution to obtain PS/PPy/Au spheres with the core/shell/shell structure. Morphology observation demonstrates that the monodisperse PS/PPy/Au microspheres compose of uniform cores and the compact coatings containing distinct two layers. X-ray diffraction and X-ray photoelectron spectroscope confirm the existence of PPy and Au on the surface of the composite spheres. This facile approach to preparing metal-coated polymer spheres supplies the potential applications in biosensors, electronics and medical diagnosis.

Sustainable steric stabilization of colloidal titania nanoparticles

Science.gov (United States)

Elbasuney, Sherif

2017-07-01

A route to produce a stable colloidal suspension is essential if mono-dispersed particles are to be successfully synthesized, isolated, and used in subsequent nanocomposite manufacture. Dispersing nanoparticles in fluids was found to be an important approach for avoiding poor dispersion characteristics. However, there is still a great tendency for colloidal nanoparticles to flocculate over time. Steric stabilization can prevent coagulation by introducing a thick adsorbed organic layer which constitutes a significant steric barrier that can prevent the particle surfaces from coming into direct contact. One of the main features of hydrothermal synthesis technique is that it offers novel approaches for sustainable nanoparticle surface modification. This manuscript reports on the sustainable steric stabilization of titanium dioxide nanoparticles. Nanoparticle surface modification was performed via two main approaches including post-synthesis and in situ surface modification. The tuneable hydrothermal conditions (i.e. temperature, pressure, flow rates, and surfactant addition) were optimized to enable controlled steric stabilization in a continuous fashion. Effective post synthesis surface modification with organic ligand (dodecenyl succinic anhydride (DDSA)) was achieved; the optimum surface coating temperature was reported to be 180-240 °C to ensure DDSA ring opening and binding to titania nanoparticles. Organic-modified titania demonstrated complete change in surface properties from hydrophilic to hydrophobic and exhibited phase transfer from the aqueous phase to the organic phase. Exclusive surface modification in the reactor was found to be an effective approach; it demonstrated surfactant loading level 2.2 times that of post synthesis surface modification. Titania was also stabilized in aqueous media using poly acrylic acid (PAA) as polar polymeric dispersant. PAA-titania nanoparticles demonstrated a durable amorphous polymeric layer of 2 nm thickness. This

Self-assembly of bacitracin-gold nanoparticles and their toxicity analysis.

Science.gov (United States)

Li, Xiaoling; Wang, Zi; Li, Yanji; Bian, Kexin; Yin, Tian; Gao, Dawei

2018-01-01

As the widely use of gold nanoparticles (AuNPs) in drug delivery, the precise control on the size and morphology of the AuNPs is urgently required. In this scenario, traditional synthesis methods cannot meet current requirement because of their inherent defects. We have depicted here a novel method for fabricating monodispersed large size gold nanoparticles, based on the self-assembly of bacitracin. The AuNPs could be facilely, low-cost, and green synthesized with repeatability and controllability in this method. The Bac gold nanoparticles (Bac-AuNPs), composed by bacitracin core and gold shell, exhibited a spherical morphology in TEM and a face-centered cubic crystal structure in X-Ray diffraction and selected area electron diffraction. The mean diameter of the Bac-AuNPs was 89nm. The nanoparticles were mono-dispersed and the zeta potential of the nanoparticles was 4.1±0.64mV. Notably, in cell viability assay, the Bac-AuNPs showed less toxicity to HepG2 cells and HEK293 cells compared to small size AuNPs. Collectively, the size, rheological characteristic and the biocompatibility supported the use of the gold nanoparticles as intracellular delivery vehicles for drug delivery, especially for tumor therapy. And this study could provide a maneuverable, controllable and green strategy for the synthesis of AuNPs, which would be applied in disease diagnosis and therapy with biosafety. Copyright © 2017. Published by Elsevier B.V.

Pore fabrication in various silica-based nanoparticles by controlled etching

KAUST Repository

Zhao, Lan

2010-07-20

A novel method based on controlled etching was developed to fabricate nanopores on preformed silica nanoparticles (<100 nm in diameter). The obtained monodisperse nanoporous particles could form highly stable homogeneous colloidal solution. Fluorescent silica nanoparticles and magnetic silica-coated γ-Fe 2O 3 nanoparticles were investigated as examples to illustrate that this strategy could be generally applied to various silica-based functional nanoparticles. The results indicated that this method was effective for generating pores on these nanoparticles without altering their original functionalities. The obtained multifunctional nanoparticles would be useful for many biological and biomedical applications. These porous nanoparticles could also serve as building blocks to fabricate three-dimensionally periodic structures that have the potential to be used as photonic crystals. © 2010 American Chemical Society.

Photoluminescence enhancement of dye-doped nanoparticles by surface plasmon resonance effects of gold colloidal nanoparticles

International Nuclear Information System (INIS)

Chu, Viet Ha; Nghiem, Thi Ha Lien; Tran, Hong Nhung; Fort, Emmanuel

2011-01-01

Due to the energy transfer from surface plasmons, the fluorescence of fluorophores near metallic nanostructures can be enhanced. This effect has been intensively studied recently for biosensor applications. This work reports on the luminescence enhancement of 100 nm Cy3 dye-doped polystyrene nanoparticles by energy transfer from surface plasmons of gold colloidal nanoparticles with sizes of 20 and 100 nm. Optimal luminescence enhancement of the fluorophores has been observed in the mixture with 20 nm gold nanoparticles. This can be attributed to the resonance energy transfer from gold nanoparticles to the fluorophore beads. The interaction between the fluorophores and gold particles is attributed to far-field interaction

Size control in the synthesis of 1-6 nm gold nanoparticles via solvent-controlled nucleation.

Science.gov (United States)

Song, Jieun; Kim, Dukhan; Lee, Dongil

2011-11-15

We report a facile synthetic route for size-controlled preparation of gold nanoparticles. Nearly monodisperse gold nanoparticles with core diameters of 1-6 nm were obtained by reducing AuP(Phenyl)(3)Cl with tert-butylamine borane in the presence of dodecanethiol in the solvent mixture of benzene and CHCl(3). Mechanism studies have shown that the size control is achieved by the solvent-controlled nucleation in which the nuclei concentration increases with increasing the fraction of CHCl(3), leading to smaller particles. It was also found that, following the solvent-controlled nucleation, particle growth occurs via ligand replacement of PPh(3) on the nuclei by Au(I)thiolate generated by the digestive etching of small particles. This synthetic strategy was successfully demonstrated with other alkanethiols of different chain length with which size-controlled, monodisperse gold nanoparticles were prepared in remarkable yield without requiring any postsynthesis treatments.

Low molecular weight block copolymers as plasticizers for polystyrene

DEFF Research Database (Denmark)

Hansen, Kristoffer Karsten; Nielsen, Charlotte Juel; Hvilsted, Søren

2005-01-01

/mol and minimum polystyrene content of 50 w/w%, which by us is predicted as the limits for solubility of polystyrene-b-alkyl in polystyrene. DSC showed polystyrene was plasticized, as seen by a reduction in glass transition temperature, by block copolymers consisting of a polystyrene block with molecular weight...... of approximately 1 kg/mol and an alkyl block with a molecular weight of approximately of 0.3 kg/mol. The efficiency of the block copolymers as plasticizers increases with decreasing molecular weight and polystyrene content. In addition, polystyrene-b-alkyl is found to be an efficient plasticizer also...... for polystyrene-b-polyisoprene-b-polystyrene (SIS) block copolymers. The end use properties of SIS plasticized with polystyrene-b-alkyl, measured as tensile strength, is higher than for SIS plasticized with dioctyl adipate. The polystyrene-b-polybutadiene-b-polystyrene and polystyrene-bpoly(propylene glycol...

Effects of Different Types of Clays and Maleic Anhydride Modified Polystyrene on Polystyrene/Clay Nanocomposites

Directory of Open Access Journals (Sweden)

M. Mehrabzadeh

2013-01-01

Full Text Available Polymer/clay nanocomposites are considered as a new subject of research in Iran and the world. Addition of a minimum amount of clay (2-5wt% can improve the mechanical properties, enhance barrier properties and reduce flammability dramatically. Polystyrene (PS exhibits high strength, high modulus and excellent dimensional stability, but it has poor ductility, elongation, and flexural modulus. By incorporating clay into polystyrene these properties can be improved. In this study preparation of polystyrene/clay nanocomposite, effects of different types of clays (Cloisite 10A andNanomer I.30TC and maleic anhydride modified polystyrene on mechanical properties of the prepared polystyrene/clay nanocomposites were evaluated. Samples were prepared by a twin screw extruder. Transmission electron microscopy (TEM and X-ray diffraction (XRD techniques were employed to evaluate the extent of intercalation and exfoliation of silicate layers in the nanocomposites. Mechanical tests show that by addition of clay and maleic anhydride modified polystyrene the flexural modulus (~30% and elongation-at-break (~40% of prepared nanocomposites have been improved. XRD and TEM results show that nanocomposite have an intercalated structure with ability to change to further exfoliation structure.

Dispersed-nanoparticle loading synthesis for monodisperse Au-titania composite particles and their crystallization for highly active UV and visible photocatalysts.

Science.gov (United States)

Sakamoto, Takeshi; Nagao, Daisuke; Noba, Masahiro; Ishii, Haruyuki; Konno, Mikio

2014-06-24

Submicrometer-sized amorphous titania spheres incorporating Au nanoparticles (NPs) were prepared in a one-pot synthesis consisting of a sol-gel reaction of titanium(IV) isopropoxide in the presence of chloroauric acid and a successive reduction with sodium borohydride in a mixed solvent of ethanol/acetonitrile. The synthesis was allowed to prepare monodisperse titania spheres that homogeneously incorporated Au NPs with sizes of ca. 7 nm. The Au NP-loaded titania spheres underwent different crystallization processes, including 500 °C calcination in air, high-temperature hydrothermal treatment (HHT), and/or low-temperature hydrothermal treatment (LHT). Photocatalytic experiments were conducted with the Au NP-loaded crystalline titania spheres under irradiation of UV and visible light. A combined process of LHT at 80 °C followed by calcination at 500 °C could effectively crystallize titania spheres maintaining the dispersion state of Au NPs, which led to photocatalytic activity higher than that of commercial P25 under UV irradiation. Under visible light irradiation, the Au NP-titania spheres prepared with a crystallization process of LHT at 80 °C for 6 h showed photocatalytic activity much higher than a commercial product of visible light photocatalyst. Structure analysis of the visible light photocatalysts indicates the importance of prevention of the Au NPs aggregation in the crystallization processes for enhancement of photocatalytic activity.

Solid polystyrene and deuterated polystyrene light output response to fast neutrons

International Nuclear Information System (INIS)

Simpson, R.; Danly, C.; Merrill, F. E.; Volegov, P. L.; Wilde, C.; Glebov, V. Yu.; Hurlbut, C.

2016-01-01

The Neutron Imaging System has proven to be an important diagnostic in studying DT implosion characteristics at the National Ignition Facility. The current system depends on a polystyrene scintillating fiber array, which detects fusion neutrons born in the DT hotspot as well as neutrons that have scattered to lower energies in the surrounding cold fuel. Increasing neutron yields at NIF, as well as a desire to resolve three-dimensional information about the fuel assembly, have provided the impetus to build and install two additional next-generation neutron imaging systems. We are currently investigating a novel neutron imaging system that will utilize a deuterated polystyrene (CD) fiber array instead of standard hydrogen-based polystyrene (CH). Studies of deuterated xylene or deuterated benzene liquid scintillator show an improvement in imaging resolution by a factor of two [L. Disdier et al., Rev. Sci. Instrum. 75, 2134 (2004)], but also a reduction in light output [V. Bildstein et al., Nucl. Instrum. Methods Phys. Res., Sect. A 729, 188 (2013); M. I. Ojaruega, Ph.D. thesis, University of Michigan, 2009; M. T. Febbraro, Ph.D. thesis, University of Michigan, 2014] as compared to standard plastic. Tests of the relative light output of deuterated polystyrene and standard polystyrene were completed using 14 MeV fusion neutrons generated through implosions of deuterium-tritium filled capsules at the OMEGA laser facility. In addition, we collected data of the relative response of these two scintillators to a wide energy range of neutrons (1-800 MeV) at the Weapons Neutrons Research Facility. Results of these measurements are presented.

Solid polystyrene and deuterated polystyrene light output response to fast neutrons

Energy Technology Data Exchange (ETDEWEB)

Simpson, R., E-mail: raspberry@lanl.gov; Danly, C.; Merrill, F. E.; Volegov, P. L.; Wilde, C. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Glebov, V. Yu. [Laboratory for Laser Energetics, Rochester, New York 14623 (United States); Hurlbut, C. [Eljen Technology, Sweetwater, Texas 79556 (United States)

2016-04-15

The Neutron Imaging System has proven to be an important diagnostic in studying DT implosion characteristics at the National Ignition Facility. The current system depends on a polystyrene scintillating fiber array, which detects fusion neutrons born in the DT hotspot as well as neutrons that have scattered to lower energies in the surrounding cold fuel. Increasing neutron yields at NIF, as well as a desire to resolve three-dimensional information about the fuel assembly, have provided the impetus to build and install two additional next-generation neutron imaging systems. We are currently investigating a novel neutron imaging system that will utilize a deuterated polystyrene (CD) fiber array instead of standard hydrogen-based polystyrene (CH). Studies of deuterated xylene or deuterated benzene liquid scintillator show an improvement in imaging resolution by a factor of two [L. Disdier et al., Rev. Sci. Instrum. 75, 2134 (2004)], but also a reduction in light output [V. Bildstein et al., Nucl. Instrum. Methods Phys. Res., Sect. A 729, 188 (2013); M. I. Ojaruega, Ph.D. thesis, University of Michigan, 2009; M. T. Febbraro, Ph.D. thesis, University of Michigan, 2014] as compared to standard plastic. Tests of the relative light output of deuterated polystyrene and standard polystyrene were completed using 14 MeV fusion neutrons generated through implosions of deuterium-tritium filled capsules at the OMEGA laser facility. In addition, we collected data of the relative response of these two scintillators to a wide energy range of neutrons (1-800 MeV) at the Weapons Neutrons Research Facility. Results of these measurements are presented.

Identification of Spinel Iron Oxide Nanoparticles by 57Fe NMR

Directory of Open Access Journals (Sweden)

SangGap Lee

2011-12-01

Full Text Available We have synthesized and studied monodisperse iron oxide nanoparticles of smaller than 10 nm to identify between the two spinel phases, magnetite and maghemite. It is shown that 57Fe NMR spectroscopy is a promising tool for distinguishing between the two phases.

Microfluidic Reactors for the Controlled Synthesis of Nanoparticles

Science.gov (United States)

Erdem, Emine Yegan

Nanoparticles have attracted a lot of attention in the past few decades due to their unique, size-dependent properties. In order to use these nanoparticles in devices or sensors effectively, it is important to maintain uniform properties throughout the system; therefore nanoparticles need to have uniform sizes -- or monodisperse. In order to achieve monodispersity, an extreme control over the reaction conditions is required during their synthesis. These reaction conditions such as temperature, concentration of reagents, residence times, etc. affect the structure of nanoparticles dramatically; therefore when the conditions vary locally in the reaction vessel, different sized nanoparticles form, causing polydispersity. In widely-used batch wise synthesis techniques, large sized reaction vessels are used to mix and heat reagents. In these types of systems, it is very hard to avoid thermal gradients and to achieve rapid mixing times as well as to control residence times. Also it is not possible to make rapid changes in the reaction parameters during the synthesis. The other drawback of conventional methods is that it is not possible to separate the nucleation of nanoparticles from their growth; this leads to combined nucleation and growth and subsequently results in polydisperse size distributions. Microfluidics is an alternative method by which the limitations of conventional techniques can be addressed. Due to the small size, it is possible to control temperature and concentration of reagents precisely as well as to make rapid changes in mixing ratios of reagents or temperature of the reaction zones. There have been several microfluidic reactors -- (microreactors) in literature that were designed to improve the size distribution of nanoparticles. In this work, two novel microfluidic systems were developed for achieving controlled synthesis of nanoparticles. The first microreactor was made out of a chemically robust polymer, polyurethane, and it was used for low

Current characteristics of λ -DNA molecules/polystyrene nanoparticles in TBE buffer solution through micro/nanofluidic capillaries under DC electric field

International Nuclear Information System (INIS)

Duan, Yifei; Zhao, Wei; Xue, Jing; Sun, Dan; Wang, Kaige; Wang, Guiren; Bai, Jintao; Li, Junjie; Gu, Changzhi

2017-01-01

In practical applications of biochips and bio-sensors, electrokinetic mechanisms are commonly employed to manipulate single bio-molecules and analyze their characteristics. To accurately and flexibly control the movement of single-molecule within micro/nanofluidic channels which are the basic components of Lab-chips, the current signals in micro/nanocapillaries filled with solutions of DNA molecules or polystyrene (PS) nanoparticles are systematically studied. Experimental results indicate that the current response along the micro/nanocapillaries can be significantly influenced by the diameter of the capillaries and the pH value of the solutions. Specifically, when there is only a pure (TBE) solution, the electric conductance does not monotonically decrease with decreasing the diameter of the capillaries, but slightly increases with decreasing the capillary diameter. When λ -DNA molecules or PS nanoparticles are added into the TBE buffer, the size effect on the electric conductance of the solutions are quite different. Although in the former, the electric conductance behaves differently from that in the pure TBE solution and decreases with the decreasing diameter, in the latter, the change is similar to that in the pure TBE solution. Besides, an abnormal ‘falling’ of the electric conductance is observed in a capillary with diameter of 200 nm. The investigation will significantly enhance the understanding on the electric properties of the solutions of biomolecules and particles in micro/nanofluidics. This is especially helpful for designing functional Lab-chip devices. (paper)

Current characteristics of λ-DNA molecules/polystyrene nanoparticles in TBE buffer solution through micro/nanofluidic capillaries under DC electric field

Science.gov (United States)

Duan, Yifei; Zhao, Wei; Xue, Jing; Sun, Dan; Wang, Kaige; Wang, Guiren; Li, Junjie; Bai, Jintao; Gu, Changzhi

2017-03-01

In practical applications of biochips and bio-sensors, electrokinetic mechanisms are commonly employed to manipulate single bio-molecules and analyze their characteristics. To accurately and flexibly control the movement of single-molecule within micro/nanofluidic channels which are the basic components of Lab-chips, the current signals in micro/nanocapillaries filled with solutions of DNA molecules or polystyrene (PS) nanoparticles are systematically studied. Experimental results indicate that the current response along the micro/nanocapillaries can be significantly influenced by the diameter of the capillaries and the pH value of the solutions. Specifically, when there is only a pure (TBE) solution, the electric conductance does not monotonically decrease with decreasing the diameter of the capillaries, but slightly increases with decreasing the capillary diameter. When λ-DNA molecules or PS nanoparticles are added into the TBE buffer, the size effect on the electric conductance of the solutions are quite different. Although in the former, the electric conductance behaves differently from that in the pure TBE solution and decreases with the decreasing diameter, in the latter, the change is similar to that in the pure TBE solution. Besides, an abnormal ‘falling’ of the electric conductance is observed in a capillary with diameter of 200 nm. The investigation will significantly enhance the understanding on the electric properties of the solutions of biomolecules and particles in micro/nanofluidics. This is especially helpful for designing functional Lab-chip devices.

FRET-mediated pH-responsive dual fluorescent nanoparticles prepared via click chemistry

Science.gov (United States)

Ouadahi, Karima; Sbargoud, Kamal; Allard, Emmanuel; Larpent, Chantal

2012-01-01

Herein, we report an easy preparation of azide-coated polystyrene-based nanoparticles (15 nm in diameter) and their surface functionalization via CuAAC with fluorophores in water. Resultant dual fluorescent nanoparticles coated with dansyl and pH-sensitive fluorescein moieties as the donor/acceptor FRET pair show a ratiometric response to pH upon excitation at a single wavelength.Herein, we report an easy preparation of azide-coated polystyrene-based nanoparticles (15 nm in diameter) and their surface functionalization via CuAAC with fluorophores in water. Resultant dual fluorescent nanoparticles coated with dansyl and pH-sensitive fluorescein moieties as the donor/acceptor FRET pair show a ratiometric response to pH upon excitation at a single wavelength. Electronic supplementary information (ESI) available: Experimental details and figures S1-S16 as mentioned in the text. See DOI: 10.1039/c2nr11413e

Synthesis and self-assembly of Chitosan-g-Polystyrene copolymer: A new route for the preparation of heavy metal nanoparticles

KAUST Repository

Francis, Raju S.

2015-01-01

Amphiphilic graft copolymers made of a Chitosan (CS) backbone and three arm polystyrene (PS) grafts were prepared by "grafting onto" strategy using Toluene Diisocyanate. IR spectroscopy and SEC show the successful grafting process. SEM pictures of Chitosan-g-Polystyrene (CS-g-PS) indicate a spherulite like surface and exhibit properties that result from the disappearance of Chitosan crystallinity. The introduced polystyrene star grafts units improve hydrophobic properties considerably as confirmed by the very high solubility of (CS-g-PS) in organic solvents. The graft copolymer which self-assembles into polymeric micelles in organic media demonstrates much better adsorption of transition and inner transition metal ions than pure Chitosan whose amine groups are not necessarily available due to crystallinity.

Synthesis of Stabilized Myrrh-Capped Hydrocolloidal Magnetite Nanoparticles

Directory of Open Access Journals (Sweden)

Ayman M. Atta

2014-07-01

Full Text Available Herein we report a new method for synthesizing stabilized magnetic nanoparticle (MNP colloids. A new class of monodisperse water-soluble magnetite nano-particles was prepared by a simple and inexpensive co-precipitation method. Iron ions and iodine were prepared by the reaction between ferric chloride and potassium iodide. The ferrous and ferric ions were hydrolyzed at low temperature at pH 9 in the presence of iodine to produce iron oxide nanoparticles. The natural product myrrh gum was used as capping agent to produce highly dispersed coated magnetite nanoparticles. The structure and morphology of the magnetic nanogel was characterized by Fourier transform infrared spectroscopy (FTIR and transmission electron microscopy (TEM, and X-ray diffraction (XRD was used to examine the crystal structure of the produced magnetite nanoparticles.

Synthesis and characterization of water-dispersible core/shell Mn-doped magnetite/Au nanoparticles for proton radiotherapy

International Nuclear Information System (INIS)

Park, Jeong Chan

2015-01-01

The surface modification of the nanomaterials is required for the biomedical use to give physiological stability, surface reactivity and targeting properties. Among many approaches for the surface modification with materials, such as polymers, organic ligands and metals, one of the most attractive ways is to employ metals. The fabrication of metal-based, monolayer coated magnetic nanoparticles has been intensively studied. However, the synthesis of metal-capped magnetic nanoparticles with monodispersities and controllable sizes is still challenged. Recently, gold-capped magnetic nanoparticles have been reported to increase stability and to provide biocompatibility. Gold-coated magnetic nanoparticles are an attractive system, which can be stabilized in biological conditions and readily functionalized through well-established surface modification chemistry. In addition, the Au coating offers plasmonic properties to magnetic nanoparticles. This makes the magnetic/Au core/shell combinations interesting for magnetic and optical applications. The monodisperse Mn:Fe3O4/Au nanoparticles have been prepared in organic solvent first and then transferred from an organic phase to an aqueous solution. The resulting core/shell-structured nanoparticles may be an attractive system for biomedical applications, which are needed both magnetic resonance imaging and optical imaging. In addition, the resulting nanoparticles may be useful for proton radiotherapy due to the enhanced therapeutic effects of secondary radiation stemmed from gold and proton beam bombardment

Plasticization effect of C60 on the fast dynamics of polystyrene and related polymers: an incoherent neutron scattering study

International Nuclear Information System (INIS)

Sanz, Alejandro; Ruppel, Markus; Cabral, Joao T; Douglas, Jack F

2008-01-01

We utilize inelastic incoherent neutron scattering (INS) to quantify how fullerenes affect the 'fast' molecular dynamics of a family of polystyrene related macromolecules. In particular, we prepared bulk nanocomposites of (hydrogenous and ring-deuterated) polystyrene and poly(4-methyl styrene) using a rapid precipitation method where the C 60 relative mass fraction ranged from 0% to 4%. Elastic window scan measurements, using a high resolution (0.9 μeV) backscattering spectrometer, are reported over a wide temperature range (2-450 K). Apparent Debye-Waller (DW) factors 2 >, characterizing the mean-square amplitude of proton displacements, are determined as a function of temperature, T. We find that the addition of C 60 to these polymers leads to a progressive increase in 2 > relative to the pure polymer value over the entire temperature range investigated, where the effect is larger for larger nanoparticle concentration. This general trend seems to indicate that the C 60 nanoparticles plasticize the fast (∼10 -15 s) local (∼1 A) dynamics of these polymer glasses. Generally, we expect nanoparticle additives to affect polymer dynamics in a similar fashion to thin films in the sense that the high interfacial area may cause both a speeding up and slowing down of the glass state dynamics depending on the polymer-surface interaction

Manipulation of polystyrene nanoparticles on a silicon wafer in the peak force tapping mode in water: pH-dependent friction and adhesion force

Energy Technology Data Exchange (ETDEWEB)

Schiwek, Simon; Stark, Robert W., E-mail: stark@csi.tu-darmstadt.de, E-mail: dietz@csi.tu-darmstadt.de; Dietz, Christian, E-mail: stark@csi.tu-darmstadt.de, E-mail: dietz@csi.tu-darmstadt.de [Center of Smart Interfaces, Technische Universität Darmstadt, Alarich-Weiss-Str. 10, 64287 Darmstadt (Germany); Physics of Surfaces, Institute of Materials Science, Technische Universität Darmstadt, Alarich-Weiss-Str. 16, 64287 Darmstadt (Germany); Heim, Lars-Oliver [Center of Smart Interfaces, Technische Universität Darmstadt, Alarich-Weiss-Str. 10, 64287 Darmstadt (Germany)

2015-03-14

The friction force between nanoparticles and a silicon wafer is a crucial parameter for cleaning processes in the semiconductor industry. However, little is known about the pH-dependency of the friction forces and the shear strength at the interface. Here, we push polystyrene nanoparticles, 100 nm in diameter, with the tip of an atomic force microscope and measure the pH-dependency of the friction, adhesion, and normal forces on a silicon substrate covered with a native silicon dioxide layer. The peak force tapping mode was applied to control the vertical force on these particles. We successively increased the applied load until the particles started to move. The main advantage of this technique over single manipulation processes is the achievement of a large number of manipulation events in short time and in a straightforward manner. Geometrical considerations of the interaction forces at the tip-particle interface allowed us to calculate the friction force and shear strength from the applied normal force depending on the pH of an aqueous solution. The results clearly demonstrated that particle removal should be performed with a basic solution at pH 9 because of the low interaction forces between particle and substrate.

Honeycomb-like thin films of polystyrene-block-poly(2-vinylpyridine) embedded with gold or silver nanoparticles formed at the planer liquid/liquid interface.

Science.gov (United States)

Wang, Di; Ma, Huihui; Chu, Chunxiao; Hao, Jingcheng; Liu, Hong-Guo

2013-07-15

Composite thin films of polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) decorated with Au or Ag nanoclusters and nanoparticles were fabricated at the interfaces of chloroform solution of PS-b-P2VP and aqueous solutions of HAuCl4 or AgNO3. Transmission electron microscopy (TEM) investigations indicated that large area of a single-layer honeycomb structure was formed, which is composed of polygons (most of them are hexagons) whose walls look like spindles with the length of several hundreds of nanometers. Large amount of Au or Ag nanoparticles are embedded in the walls and the undersides of the honeycomb structures. The formation of these novel composite structures was attributed to the adsorption of block copolymer molecules and inorganic species of AuCl4(-) and Ag(+) ions at the liquid-liquid interface, the combination of the polymer molecules and the inorganic ions, and the self-assembly of the composite molecules. After UV-light irradiation and KBH4 aqueous solution treatment, the inorganic species were reduced completely, as confirmed by UV-vis spectra and X-ray photoelectron spectra. These composite films exhibited high catalytic activities for the reduction of 4-nitrophenol (4-NP) by KBH4 in aqueous solutions. Copyright © 2013 Elsevier Inc. All rights reserved.

Raman Spectroscopy of Single Nanoparticles in a Double-Nanohole Optical Tweezer System

OpenAIRE

Jones, Steven; Balushi, Ahmed A. Al; Gordon, Reuven

2015-01-01

A double nanohole in a metal film was used to trap nanoparticles (20 nm diameter) and simultaneously record their Raman spectrum using the trapping laser as the excitation source. This allowed for the identification of characteristic Stokes lines for titania and polystyrene nanoparticles, showing the capability for material identification of nanoparticles once trapped. Increased Raman signal is observed for the trapping of multiple nanoparticles. This system combines the benefits of nanoparti...

Simulative calculation of bromo-polystyrene mechanical properties

CERN Document Server

Wang Chao; Tang Yong Jian

2002-01-01

The non-crystal model of polystyrene and bromo-polystyrene was established with the help of simulative software in the computer. DREIDING was chosen as force field and its parameters is modified according to the published data. Based on the calculation results and other published data the mechanism properties of polystyrene and bromo-polystyrene, such as bulk module, Yong's module and Poisson's ratios, were discussed

Cytotoxicity of functionalized polystyrene latex nanoparticles toward lactic acid bacteria, and comparison with model microbes

Energy Technology Data Exchange (ETDEWEB)

Nomura, Toshiyuki, E-mail: nomura@chemeng.osakafu-u.ac.jp; Kuriyama, Yuta; Tokumoto, Hayato; Konishi, Yasuhiro [Osaka Prefecture University, Department of Chemical Engineering (Japan)

2015-02-15

The cytotoxicity and colloidal behavior of surface-functionalized polystyrene latex (PSL) nanoparticles (NPs) (nominal diameter: 100 nm) toward a model gram positive bacterium Lactococcus lactis JCM 5805 were examined. Nearly all the L. lactis cells exposed to the negatively charged PSL NPs survived because the surface of the bacterial cell was charged negatively, and the NPs therefore hardly adhere to the cell surface. In contrast, the positively charged PSL NPs adhered to the L. lactis cell surface but were not entrapped within the cell, and cell death subsequently occurred. The bacterial growth curves after the toxic NP exposure suggested that NP toxicity did not affect the specific growth phase, but did affect lag time. These results indicated that the cells were damaged by the cell disruption that resulted from the adhesion of the NPs to the cell surface. Finally, the cytotoxicity of the toxic, positively charged PSL NPs toward L. lactis was compared with that displayed toward a model gram negative bacterium Escherichia coli and a model eukaryote Saccharomyces cerevisiae. The cytotoxic behaviors of NPs on L. lactis and E. coli were similar, and depended not on the bacterial surface structure, but rather the environmental ionic strength. In contrast, the cytotoxicity of the prokaryote bacteria was higher than that toward the model eukaryote S. cerevisiae. The difference between the NP sensitivities of the prokaryote and eukaryote resulted from the prokaryote’s lack of an endocytotic pathway.

Cytotoxicity of functionalized polystyrene latex nanoparticles toward lactic acid bacteria, and comparison with model microbes

Science.gov (United States)

Nomura, Toshiyuki; Kuriyama, Yuta; Tokumoto, Hayato; Konishi, Yasuhiro

2015-02-01

The cytotoxicity and colloidal behavior of surface-functionalized polystyrene latex (PSL) nanoparticles (NPs) (nominal diameter: 100 nm) toward a model gram positive bacterium Lactococcus lactis JCM 5805 were examined. Nearly all the L. lactis cells exposed to the negatively charged PSL NPs survived because the surface of the bacterial cell was charged negatively, and the NPs therefore hardly adhere to the cell surface. In contrast, the positively charged PSL NPs adhered to the L. lactis cell surface but were not entrapped within the cell, and cell death subsequently occurred. The bacterial growth curves after the toxic NP exposure suggested that NP toxicity did not affect the specific growth phase, but did affect lag time. These results indicated that the cells were damaged by the cell disruption that resulted from the adhesion of the NPs to the cell surface. Finally, the cytotoxicity of the toxic, positively charged PSL NPs toward L. lactis was compared with that displayed toward a model gram negative bacterium Escherichia coli and a model eukaryote Saccharomyces cerevisiae. The cytotoxic behaviors of NPs on L. lactis and E. coli were similar, and depended not on the bacterial surface structure, but rather the environmental ionic strength. In contrast, the cytotoxicity of the prokaryote bacteria was higher than that toward the model eukaryote S. cerevisiae. The difference between the NP sensitivities of the prokaryote and eukaryote resulted from the prokaryote's lack of an endocytotic pathway.

Cytotoxicity of functionalized polystyrene latex nanoparticles toward lactic acid bacteria, and comparison with model microbes

International Nuclear Information System (INIS)

Nomura, Toshiyuki; Kuriyama, Yuta; Tokumoto, Hayato; Konishi, Yasuhiro

2015-01-01

The cytotoxicity and colloidal behavior of surface-functionalized polystyrene latex (PSL) nanoparticles (NPs) (nominal diameter: 100 nm) toward a model gram positive bacterium Lactococcus lactis JCM 5805 were examined. Nearly all the L. lactis cells exposed to the negatively charged PSL NPs survived because the surface of the bacterial cell was charged negatively, and the NPs therefore hardly adhere to the cell surface. In contrast, the positively charged PSL NPs adhered to the L. lactis cell surface but were not entrapped within the cell, and cell death subsequently occurred. The bacterial growth curves after the toxic NP exposure suggested that NP toxicity did not affect the specific growth phase, but did affect lag time. These results indicated that the cells were damaged by the cell disruption that resulted from the adhesion of the NPs to the cell surface. Finally, the cytotoxicity of the toxic, positively charged PSL NPs toward L. lactis was compared with that displayed toward a model gram negative bacterium Escherichia coli and a model eukaryote Saccharomyces cerevisiae. The cytotoxic behaviors of NPs on L. lactis and E. coli were similar, and depended not on the bacterial surface structure, but rather the environmental ionic strength. In contrast, the cytotoxicity of the prokaryote bacteria was higher than that toward the model eukaryote S. cerevisiae. The difference between the NP sensitivities of the prokaryote and eukaryote resulted from the prokaryote’s lack of an endocytotic pathway

'Green' synthesis of starch capped CdSe nanoparticles at room temperature

International Nuclear Information System (INIS)

Li Jinhua; Ren Cuiling; Liu Xiaoyan; Hu Zhide; Xue Desheng

2007-01-01

The nearly monodisperse starch capped CdSe nanoparticles were successfully synthesized by a simple and 'green' route at room temperature. The as-prepared nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), UV-vis absorption and photoluminescence (PL) spectra. The XRD analysis showed that the starch capped CdSe nanoparticles were of the cubic structure, the average particle size was calculated to be about 3 nm according to the Debye-Scherrer equation. TEM micrographs exhibited that the starch capped CdSe nanoparticles were well dispersed than the uncapped CdSe nanoparticles, the mean particles size of the capped CdSe was about 3 nm in the TEM image, which was in good agreement with the XRD

Preparation and properties of hybrid monodispersed magnetic α-Fe2O3 based chitosan nanocomposite film for industrial and biomedical applications.

Science.gov (United States)

Singh, Jay; Srivastava, M; Dutta, Joydeep; Dutta, P K

2011-01-01

In this study, hydrothermally prepared magnetic α-Fe2O3 nanoparticles were dispersed in chitosan (CH) solution to fabricate nanocomposite film. X-ray diffraction (XRD) patterns indicated that the α-Fe2O3 nanoparticles were pure α-Fe2O3 with rhombohedral structures, and the fabrication of CH did not result in a phase change. The scanning electron microscopy (SEM) and transmission electron microscope (TEM) results showed that the hexagonal and spherical monodispersed α-Fe2O3 nanoparticles were encapsulated into the spherical dumb shaped CH-α-Fe2O3 nanocomposite film with a mean diameter of ∼87 and ∼110 nm respectively. The α-Fe2O3 nanoparticles and CH-α-Fe2O3 nanocomposite film were also characterized by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and vibrating sample magnetometer (VSM). Magnetic measurements revealed that the saturated magnetization (Ms) and remanent magnetization (Mr) of the pure α-Fe2O3 nanoparticles reached 0.573 emu/g and 0.100 emu/g respectively and the nanoparticles showed the characteristics of weak ferromagnetic before and after coating with CH. Copyright © 2010 Elsevier B.V. All rights reserved.

Hollow magnetic nano-CO3O4/polystyrene microspheres synthesized through radiation induced interfacial polymerization

International Nuclear Information System (INIS)

Zhang Wei; Wang Mozhen; Wang Shufeng; Zhang Zhicheng

2010-01-01

Co 3 O 4 nanoparticles (around 8 nm) were synthesized hydrothermally by dissolving Co 2+ in the mixture of ethanol and water, and then decorated with oleic acid to endow them with hydrophobic surface nature. After that, nano-particles were added into emulsion which consisted by sodium dodecyl sulfate, water, styrene and cetyl alcohol. Hollow magnetic composite spheres were prepared by irradiated the emulsion with γ-rays. The final products are thoroughly characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), field-emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) techniques, which showed the formation of hollow magnetic composite spheres. The influence of addition dosage of nano-particles, sodium dodecyl sulfate and the types of nano-particles on the average size and shape of hollow composites were studied. The effects of nano-particles to the polymerization of styrene were studied by kinetics. Nano-particles are capsulated by polystyrene to form hollow composites, which confirmed by XPS results. Finally, magnetic property of hollow composites is compared with pure nano-Co 3 O 4 . (authors)

Antioxidant and anti-inflammatory activities of silver nanoparticles biosynthesized from aqueous leaves extracts of four Terminalia species

Science.gov (United States)

El-Rafie, Hanaa Mohamed; Abdel-Aziz Hamed, Manal

2014-09-01

The environmentally friendly synthesis of nanoparticles process is a revolutionary step in the field of nanotechnology. In recent years plant mediated biological synthesis of nanoparticles has been gaining importance due to its simplicity and eco-friendliness. In this study, a simple and an efficient eco-friendly approach for the biosynthesis of stable, monodisperse silver nanoparticles using aqueous extracts of four Terminalia species, namely, Terminalia catappa, Terminalia mellueri, Terminalia bentazoe and Terminalia bellerica were described. The silver nanoparticles were characterized in terms of synthesis, capping functionalities (polysaccharides, phenolics and flavonoidal compounds) and microscopic evaluation by UV-visible spectroscopy, Fourier transform infrared spectroscopy and transmission electron microscopy. The results showed a simple and feasible approach for obtaining stable aqueous monodispersive silver nanoparticles. Furthermore, biological activity of the biosynthesized silver nanoparticles was examined. Concerning this, dose-dependent antioxidant activity of silver nanoparticles imparted by the plant phenolic and flavonoidal components was evaluated using in vitro 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and found to be comparable to standard ascorbic acid. The same holds true for the anti-inflammatory activity where Terminalia catappa and Terminalia mellueri have a high-test inhibition percentage better than that of ascorbic acid in the carrageenan induced hind paw edema. The results also revealed that the aqueous extract of Terminallia catapa and its silver nanoparticles recorded the most potent in vivo antioxidant effect.

Uptake and bio-reactivity of polystyrene nanoparticles is affected by surface modifications, ageing and LPS adsorption: in vitro studies on neural tissue cells

Science.gov (United States)

Murali, Kumarasamy; Kenesei, Kata; Li, Yang; Demeter, Kornél; Környei, Zsuzsanna; Madarász, Emilia

2015-02-01

Because of their capacity of crossing an intact blood-brain barrier and reaching the brain through an injured barrier or via the nasal epithelium, nanoparticles have been considered as vehicles to deliver drugs and as contrast materials for brain imaging. The potential neurotoxicity of nanoparticles, however, is not fully explored. Using particles with a biologically inert polystyrene core material, we investigated the role of the chemical composition of particle surfaces in the in vitro interaction with different neural cell types. PS NPs within a size-range of 45-70 nm influenced the metabolic activity of cells depending on the cell-type, but caused toxicity only at extremely high particle concentrations. Neurons did not internalize particles, while microglial cells ingested a large amount of carboxylated but almost no PEGylated NPs. PEGylation reduced the protein adsorption, toxicity and cellular uptake of NPs. After storage (shelf-life >6 months), the toxicity and cellular uptake of NPs increased. The altered biological activity of ``aged'' NPs was due to particle aggregation and due to the adsorption of bioactive compounds on NP surfaces. Aggregation by increasing the size and sedimentation velocity of NPs results in increased cell-targeted NP doses. The ready endotoxin adsorption which cannot be prevented by PEG coating, can render the particles toxic. The age-dependent changes in otherwise harmless NPs could be the important sources for variability in the effects of NPs, and could explain the contradictory data obtained with ``identical'' NPs.Because of their capacity of crossing an intact blood-brain barrier and reaching the brain through an injured barrier or via the nasal epithelium, nanoparticles have been considered as vehicles to deliver drugs and as contrast materials for brain imaging. The potential neurotoxicity of nanoparticles, however, is not fully explored. Using particles with a biologically inert polystyrene core material, we investigated the

Room temperature synthesis of water-repellent polystyrene nanocomposite coating

International Nuclear Information System (INIS)

Guo Yonggang; Jiang Dong; Zhang Xia; Zhang Zhijun; Wang Qihua

2010-01-01

A stable superhydrophobic polystyrene nanocomposite coating was fabricated by means of a very simple and easy method. The coating was characterized by scanning electron microscopy and X-ray photoelectron spectrum. The wettability of the products was also investigated. By adding the surface-modified SiO 2 nanoparticles, the wettability of the coating changed to water-repellent superhydrophobic, not only for pure water, but also for a wide pH range of corrosive liquids. The influence of the drying temperature and SiO 2 content on the wettability of the nanocomposite coating was also investigated. It was found that both factors had little or no significant effect on the wetting behavior of the coating surface.

Preparation of carbon paste electrodes including poly(styrene) attached glycine-Pt(IV) for amperometric detection of glucose.

Science.gov (United States)

Dönmez, Soner; Arslan, Fatma; Sarı, Nurşen; Kurnaz Yetim, Nurdan; Arslan, Halit

2014-04-15

In this study, a novel carbon paste electrode that is sensitive to glucose was prepared using the nanoparticles modified (4-Formyl-3-methoxyphenoxymethyl) with polystyren (FMPS) with L-Glycine-Pt(IV) complexes. Polymeric nanoparticles having Pt(IV) ion were prepared from (4-Formyl-3-methoxyphenoxymethyl) polystyren, glycine and PtCl4 by template method. Glucose oxidase enzyme was immobilized to a modified carbon paste electrode (MCPE) by cross-linking with glutaraldehyde. Determination of glucose was carried out by oxidation of enzymatically produced H2O2 at 0.5 V vs. Ag/AgCl. Effects of pH and temperature were investigated, and optimum parameters were found to be 8.0 and 55°C, respectively. Linear working range of the electrode was 5.0×10(-6)-1.0×10(-3) M, R(2)=0.997. Storage stability and operational stability of the enzyme electrode were also studied. Glucose biosensor gave perfect reproducible results after 10 measurements with 2.3% relative standard deviation. Also, it had good storage stability (gave 53.57% of the initial amperometric response at the end of 33th day). © 2013 Published by Elsevier B.V.

μ-reactor measurements of catalytic activity of mass selected nano-particles

DEFF Research Database (Denmark)

Riedel, Jakob Nordheim

The work of this thesis revolves around catalytic activity measurements of nano-particles tested using a μ-reactor platform, developed and produced at DTU, in a collaboration between CINF and Nanotech. The thesis contains the results from two separate research projects; both utilising μ-reactors ......The work of this thesis revolves around catalytic activity measurements of nano-particles tested using a μ-reactor platform, developed and produced at DTU, in a collaboration between CINF and Nanotech. The thesis contains the results from two separate research projects; both utilising μ......-reactors in combination with surface science techniques and computer simulations. The first project described is a study of hydrogen dissociation on mono-disperse platinum clusters. The second project studies methanation from carbon monoxide and hydrogen on nano-particles of nickel-iron alloys. The second study is a work...... in progress, and the corresponding chapter aims to summarise the results so far. Other projects are not included in the thesis because they are inconclusive or dead ends. Hydrogen dissociation was studied by the H2/D2 exchange reaction on SiO2-supported mono-disperse platinum clusters in a -reactor...

Application of “Boomerang” Linear Polystyrene-Stabilized Pd Nanoparticles to a Series of C-C Coupling Reactions in Water

Directory of Open Access Journals (Sweden)

Atsushi Ohtaka

2015-02-01

Full Text Available The application of a catch-and-release system for soluble Pd species between water (reaction medium and polystyrene (polymer support was examined in the Suzuki coupling reaction with 2-bromothiophene and the Heck reaction with styrene or bromobenzene. Although a slight increase in particle size was observed by TEM after re-stabilization of the Pd species on linear polystyrene, no agglomeration was observed.

Effect of Recycling in Post-Consumer Polystyrene Cups

OpenAIRE

Ahmed, Mehnaz

2016-01-01

The aim of the thesis was to recycle post-consumer polystyrene cups and to analyze the changes in mechanical and rheological properties of the recycled polystyrene. The me-chanical properties were tensile strength, Young’s modulus and the rheological proper-ties was melt flow index. In order to analyze the changes in properties, material testing results of pristine polystyrene were compared with the recycled polystyrene. The same polystyrene material was recycled and tested twice in order to ...

Synthesis and study of optical and thermal properties of Mn doped CdS nanoparticles using polyvinylpyrrolidone

International Nuclear Information System (INIS)

Rajesh Kumar, M.; Murugadoss, G.

2014-01-01

High quality and monodispersed CdS:Mn (1–5%) nanoparticles were synthesized by chemical precipitation method using PVP as surfactant. The structure and morphology of the CdS:Mn were investigated by means of XRD, FT-IR, TEM, UV–visible, PL, EPR and TG-DTA. XRD study was confirmed the formation cubic structured CdS:Mn nanoparticles. The optical absorption of Mn doped CdS nanoparticles was found to be 420–432 nm, which is significantly decreased from the bulk CdS material. Photoluminescence spectroscopy of the CdS:Mn nanocrystals showed a strong emission peak at 535 nm near the band edge along with a week green emission around 575 nm. The PL property of annealed (255 °C–850 °C) samples was also investigated under different excitations. The presence of PVP on the CdS:Mn surface and incorporated the Mn ion into CdS lattice were identified by FT-IR and EPR spectroscopy, respectively. TEM result showed spherical with monodispersed particles with typical size of 3.8–4.3 nm, which is a favorable characteristic for many applications. The major weight loss and gain were found in the thermogravimetric analysis (TGA) which corresponds to the decomposition and oxidation of the samples. -- Highlights: • An optimum concentration of Mn was selected through optical study. • PL emission was improved by addition of capping agent. • The PL enhancement indicates good crystal quality and monodisperse of the synthesized CdS:Mn nanoparticles by chemical method

Raman spectroscopy of single nanoparticles in a double-nanohole optical tweezer system

International Nuclear Information System (INIS)

Jones, Steven; Al Balushi, Ahmed A; Gordon, Reuven

2015-01-01

A double nanohole in a metal film was used to trap nanoparticles (20 nm diameter) and simultaneously record their Raman spectrum using the trapping laser as the excitation source. This allowed for the identification of characteristic Stokes lines for titania and polystyrene nanoparticles, showing the capability for material identification of nanoparticles once trapped. Increased Raman signal was observed for the trapping of multiple nanoparticles. This system combines the benefits of nanoparticle isolation and manipulation with unique identification. (fast track communication)

Preparation and Characterization of Polystyrene-Silver NanocompositeUsing MicroemulsionMethod and its Antibacterial Activity

Directory of Open Access Journals (Sweden)

A. Salabat

2014-07-01

Full Text Available Polymer nanocomposites containing metals have been used in a wide range of applications due to their versatility, and tunable characteristics including physical, chemical, biological and mechanical properties. In this research work polystyrene-silver nanocomposite has been produced using polymerization of a w/o microemulsion system. Styrene monomer was used as the oil or continues phase of the microemulsion system and polymerized following formation of Ag nanoparticles in the fluid medium. The UV-vis absorption and dynamic light scattering methods have been used to trace the growth process and size distribution of the Ag nanoparticles in the microemulsion system. Scanning electron microscopy (SEM was used to determine the morphology and particle size of the Ag particles in the synthesized nanocomposites.

Effect of bidispersity in grafted chain length on grafted chain conformations and potential of mean force between polymer grafted nanoparticles in a homopolymer matrix.

Science.gov (United States)

Nair, Nitish; Wentzel, Nathaniel; Jayaraman, Arthi

2011-05-21

In efforts to produce polymeric materials with tailored physical properties, significant interest has grown around the ability to control the spatial organization of nanoparticles in polymer nanocomposites. One way to achieve controlled particle arrangement is by grafting the nanoparticle surface with polymers that are compatible with the matrix, thus manipulating the interfacial interactions between the nanoparticles and the polymer matrix. Previous work has shown that the molecular weight of the grafted polymer, both at high grafting density and low grafting density, plays a key role in dictating the effective inter-particle interactions in a polymer matrix. At high grafting density nanoparticles disperse (aggregate) if the graft molecular weight is higher (lower) than the matrix molecular weight. At low grafting density the longer grafts can better shield the nanoparticle surface from direct particle-particle contacts than the shorter grafts and lead to the dispersion of the grafted particles in the matrix. Despite the importance of graft molecular weight, and evidence of non-trivial effects of polydispersity of chains grafted on flat surfaces, most theoretical work on polymer grafted nanoparticles has only focused on monodisperse grafted chains. In this paper, we focus on how bidispersity in grafted chain lengths affects the grafted chain conformations and inter-particle interactions in an implicit solvent and in a dense homopolymer polymer matrix. We first present the effects of bidispersity on grafted chain conformations in a single polymer grafted particle using purely Monte Carlo (MC) simulations. This is followed by calculations of the potential of mean force (PMF) between two grafted particles in a polymer matrix using a self-consistent Polymer Reference Interaction Site Model theory-Monte Carlo simulation approach. Monte Carlo simulations of a single polymer grafted particle in an implicit solvent show that in the bidisperse polymer grafted particles

Highly stable, protein capped gold nanoparticles as effective drug delivery vehicles for amino-glycosidic antibiotics

International Nuclear Information System (INIS)

Rastogi, Lori; Kora, Aruna Jyothi; Arunachalam, J.

2012-01-01

A method for the production of highly stable gold nanoparticles (Au NP) was optimized using sodium borohydride as reducing agent and bovine serum albumin as capping agent. The synthesized nanoparticles were characterized using UV–visible spectroscopy, transmission electron microscopy, X‐ray diffraction (XRD) and dynamic light scattering techniques. The formation of gold nanoparticles was confirmed from the appearance of pink colour and an absorption maximum at 532 nm. These protein capped nanoparticles exhibited excellent stability towards pH modification and electrolyte addition. The produced nanoparticles were found to be spherical in shape, nearly monodispersed and with an average particle size of 7.8 ± 1.7 nm. Crystalline nature of the nanoparticles in face centered cubic structure is confirmed from the selected‐area electron diffraction and XRD patterns. The nanoparticles were functionalized with various amino-glycosidic antibiotics for utilizing them as drug delivery vehicles. Using Fourier transform infrared spectroscopy, the possible functional groups of antibiotics bound to the nanoparticle surface have been examined. These drug loaded nanoparticle solutions were tested for their antibacterial activity against Gram-negative and Gram-positive bacterial strains, by well diffusion assay. The antibiotic conjugated Au NP exhibited enhanced antibacterial activity, compared to pure antibiotic at the same concentration. Being protein capped and highly stable, these gold nanoparticles can act as effective carriers for drugs and might have considerable applications in the field of infection prevention and therapeutics. - Highlights: ► Method for NaBH 4 reduced and BSA capped gold nanoparticle was standardized. ► Nanoparticles were spherical and nearly monodispersed with a size of 7.8 nm. ► Nanoparticles are extremely stable towards pH modification and electrolyte addition. ► Antibiotic conjugated nanoparticles exhibited enhanced antibacterial activity

Detecting single viruses and nanoparticles using whispering gallery microlasers.

Science.gov (United States)

He, Lina; Ozdemir, Sahin Kaya; Zhu, Jiangang; Kim, Woosung; Yang, Lan

2011-06-26

There is a strong demand for portable systems that can detect and characterize individual pathogens and other nanoscale objects without the use of labels, for applications in human health, homeland security, environmental monitoring and diagnostics. However, most nanoscale objects of interest have low polarizabilities due to their small size and low refractive index contrast with the surrounding medium. This leads to weak light-matter interactions, and thus makes the label-free detection of single nanoparticles very difficult. Micro- and nano-photonic devices have emerged as highly sensitive platforms for such applications, because the combination of high quality factor Q and small mode volume V leads to significantly enhanced light-matter interactions. For example, whispering gallery mode microresonators have been used to detect and characterize single influenza virions and polystyrene nanoparticles with a radius of 30 nm (ref. 12) by measuring in the transmission spectrum either the resonance shift or mode splitting induced by the nanoscale objects. Increasing Q leads to a narrower resonance linewidth, which makes it possible to resolve smaller changes in the transmission spectrum, and thus leads to improved performance. Here, we report a whispering gallery mode microlaser-based real-time and label-free detection method that can detect individual 15-nm-radius polystyrene nanoparticles, 10-nm gold nanoparticles and influenza A virions in air, and 30 nm polystyrene nanoparticles in water. Our approach relies on measuring changes in the beat note that is produced when an ultra-narrow emission line from a whispering gallery mode microlaser is split into two modes by a nanoscale object, and these two modes then interfere. The ultimate detection limit is set by the laser linewidth, which can be made much narrower than the resonance linewidth of any passive resonator. This means that microlaser sensors have the potential to detect objects that are too small to be

Enhanced bio-compatibility of ferrofluids of self-assembled superparamagnetic iron oxide-silica core-shell nanoparticles

Digital Repository Service at National Institute of Oceanography (India)

Narayanan, T.N.; Mary, A.P.R.; Swalih, P.K.A.; Kumar, D.S.; Makarov, D.; Albrecht, M.; Puthumana, J.; Anas, A.; Anantharaman, A.

-interacting, monodispersed and hence the synthesis of such nanostructures has great relevance in the realm of nanoscience. Silica-coated superparamagnetic iron oxide nanoparticles based ferrofluids were prepared using polyethylene glycol as carrier fluid by employing a...

Thermal Decomposition of Radiation-Damaged Polystyrene

International Nuclear Information System (INIS)

J Abrefah, J.; Klinger, G.S.

2000-01-01

The radiation-damaged polystyrene material (''polycube'') used in this study was synthesized by mixing a high-density polystyrene (''Dylene Fines No. 100'') with plutonium and uranium oxides. The polycubes were used on the Hanford Site in the 1960s for criticality studies to determine the hydrogen-to-fissile atom ratios for neutron moderation during processing of spent nuclear fuel. Upon completion of the studies, two methods were developed to reclaim the transuranic (TRU) oxides from the polymer matrix: (1) burning the polycubes in air at 873 K; and (2) heating the polycubes in the absence of oxygen and scrubbing the released monomer and other volatile organics using carbon tetrachloride. Neither of these methods was satisfactory in separating the TRU oxides from the polystyrene. Consequently, the remaining polycubes were sent to the Hanford Plutonium Finishing Plant (PFP) for storage. Over time, the high dose of alpha and gamma radiation has resulted in a polystyrene matrix that is highly cross-linked and hydrogen deficient and a stabilization process is being developed in support of Defense Nuclear Facility Safety Board Recommendation 94-1. Baseline processes involve thermal treatment to pyrolyze the polycubes in a furnace to decompose the polystyrene and separate out the TRU oxides. Thermal decomposition products from this degraded polystyrene matrix were characterized by Pacific Northwest National Laboratory to provide information for determining the environmental impact of the process and for optimizing the process parameters. A gas chromatography/mass spectrometry (GC/MS) system coupled to a horizontal tube furnace was used for the characterization studies. The decomposition studies were performed both in air and helium atmospheres at 773 K, the planned processing temperature. The volatile and semi-volatile organic products identified for the radiation-damaged polystyrene were different from those observed for virgin polystyrene. The differences were in the

Simple Coatings to Render Polystyrene Protein Resistant

Directory of Open Access Journals (Sweden)

Marcelle Hecker

2018-02-01

Full Text Available Non-specific protein adsorption is detrimental to the performance of many biomedical devices. Polystyrene is a commonly used material in devices and thin films. Simple reliable surface modification of polystyrene to render it protein resistant is desired in particular for device fabrication and orthogonal functionalisation schemes. This report details modifications carried out on a polystyrene surface to prevent protein adsorption. The trialed surfaces included Pluronic F127 and PLL-g-PEG, adsorbed on polystyrene, using a polydopamine-assisted approach. Quartz crystal microbalance with dissipation (QCM-D results showed only short-term anti-fouling success of the polystyrene surface modified with F127, and the subsequent failure of the polydopamine intermediary layer in improving its stability. In stark contrast, QCM-D analysis proved the success of the polydopamine assisted PLL-g-PEG coating in preventing bovine serum albumin adsorption. This modified surface is equally as protein-rejecting after 24 h in buffer, and thus a promising simple coating for long term protein rejection of polystyrene.

Environmentally friendly synthesis of organic-soluble silver nanoparticles for printed electronics

International Nuclear Information System (INIS)

Lee, Kwi Jong; Jun, Byung Ho; Choi, Junrak; Lee, Young Il; Joung, Jaewoo; Oh, Yong Soo

2007-01-01

In this study, we attempted to synthesize organic-soluble silver nanoparticles in the concentrated organic phase with an environmentally friendly method. The fully organic phase system contains silver acetate as a silver precursor, oleic acid as both a medium and a capping molecule, and tin acetate as a reducing agent. Monodisperse silver nanoparticles with average diameters of ca. 5 nm can be easily synthesized at large scale. Only a small usage of tin acetate ( 90%). Also, it was investigated that the residual tin atom does not exist in the synthesized silver nanoparticles. This implied that tin acetate acts as a reducing catalyst

Sustainable steric stabilization of colloidal titania nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Elbasuney, Sherif, E-mail: sherif_basuney2000@yahoo.com

2017-07-01

Graphical abstract: Controlled surface properties of titania nanoparticles via surface modification, flocculation from aqueous phase (a), stabilization in aqueous phase (b), extraction to organic phase (c). - Highlights: • Complete change in surface properties of titania nanoparticles from hydrophilic to hydrophobic. • Harvesting the formulated nanoparticles from the aqueous phase to the organic phase. • Exclusive surface modification in the reactor during nanoparticle synthesis. • Sustainable stabilization of titania nanoparticles in aqueous media with polar polymeric dispersant. - Abstract: A route to produce a stable colloidal suspension is essential if mono-dispersed particles are to be successfully synthesized, isolated, and used in subsequent nanocomposite manufacture. Dispersing nanoparticles in fluids was found to be an important approach for avoiding poor dispersion characteristics. However, there is still a great tendency for colloidal nanoparticles to flocculate over time. Steric stabilization can prevent coagulation by introducing a thick adsorbed organic layer which constitutes a significant steric barrier that can prevent the particle surfaces from coming into direct contact. One of the main features of hydrothermal synthesis technique is that it offers novel approaches for sustainable nanoparticle surface modification. This manuscript reports on the sustainable steric stabilization of titanium dioxide nanoparticles. Nanoparticle surface modification was performed via two main approaches including post-synthesis and in situ surface modification. The tuneable hydrothermal conditions (i.e. temperature, pressure, flow rates, and surfactant addition) were optimized to enable controlled steric stabilization in a continuous fashion. Effective post synthesis surface modification with organic ligand (dodecenyl succinic anhydride (DDSA)) was achieved; the optimum surface coating temperature was reported to be 180–240 °C to ensure DDSA ring opening

1.7 nm Platinum Nanoparticles: Synthesis with Glucose Starch, Characterization and Catalysis

DEFF Research Database (Denmark)

Engelbrekt, Christian; Sørensen, Karsten Holm; Lubcke, T.

2010-01-01

Monodisperse platinum nanoparticles (PtNPs) were synthesized by a green recipe. Glucose serves as a reducing agent and starch as a stabilization agent to protect the freshly formed PtNP cores in buffered aqueous solutions. Among the ten buffers studied, 2-(N-morpholino)ethanesulfonic acid (MES), ...

Poloxamer-Decorated Polymer Nanoparticles for Lung Surfactant Compatibility

DEFF Research Database (Denmark)

Beck-Broichsitter, Moritz; Bohr, Adam; Ruge, Christian A

2017-01-01

Lung-delivered polymer nanoparticles provoked dysfunction of the essential lung surfactant system. A steric shielding of the nanoparticle surface with poloxamers could minimize the unwanted interference of polymer nanoparticles with the biophysical function of lung surfactant. The extent of poly......(styrene) and poly(lactide) nanoparticle-induced lung surfactant inhibition could be related to the type and content of the applied poloxamer. Escalations of the adsorbed coating layer thickness (>3 nm) as well as concentration (brush- rather than mushroom-like conformation of poly(ethylene glycol), chain......-associated proteins. Poloxamer-modified polymer nanoparticles represent a promising nanomedicine platform intended for respiratory delivery revealing negligible effects on the biophysical functionality of the lining layer present in the deep lungs....

Organosilane oxidation by water catalysed by large gold nanoparticles in a membrane reactor

NARCIS (Netherlands)

Gitis, V.; Beerthuis, R.; Shiju, N.R.; Rothenberg, G.

2014-01-01

We show that gold nanoparticles catalyse the oxidation of organosilanes using water as oxidant at ambient conditions. Remarkably, monodispersions of small gold particles (3.5 nm diameter) and large ones (6-18 nm diameter) give equally good conversion rates. This is important because separating large

Oxide nanoparticle-based fabrication and optical properties of Cu(In1−xGax)S2 absorber layer for solar cells

International Nuclear Information System (INIS)

Choi, Yo-Min; Lee, Young-In; Kim, Bum-Sung; Choa, Yong-Ho

2013-01-01

The compound Cu(In 1−x Ga x )S 2 (CIGS) was synthesized using copper oxide, indium oxide and gallium oxide mixture (CIGO) nanoparticles using salt-assisted ultrasonic spray pyrolysis (SAUSP). Under this method, CIGS can be produced without the complicated restrictions of a vacuum and an inert atmosphere. The band gap of CIGS can be controlled by introducing the desired stoichiometric quantities of starting materials. In order to synthesize CIGO nanoparticles, various NaCl/precursor ratios were used to accomplish the SAUSP process and ultimately monodisperse CIGO nanoparticles with average particle size of 9 nm without hard agglomeration were obtained. Subsequently, the CIGO nanoparticles were sulfurized to form the CIGS in H 2 S/Ar atmosphere at 500 °C. The CIGS obtained in the present study has the various band gap ranging from 1.67 to 2.34 eV depending on the Ga / (In + Ga) ratio, and those band gap correspond to the respective bulk materials. - Highlights: • CIGS is obtained using Cu, In and Ga oxide mixture (CIGO) nanoparticles. • Salt-assisted ultrasonic spray pyrolysis is used to synthesize CIGO nanoparticles. • Nine nanometers of monodisperse CIGO nanoparticles without hard agglomeration is obtained. • The band gap of CIGS can be controlled by introducing the desired ratio of precursor

Preparation and characterization of ω-functionalized polystyrene-magnetite nanocomposites

International Nuclear Information System (INIS)

Jiang Liming; Sun Weilin; Kim, Jungahn

2007-01-01

Magnetite (Fe 3 O 4 ) nanoparticles were prepared by in situ precipitation and oxidation of ferrous ions in the presence of ω-functionalized polystyrenes having carboxylate, sulfonate, thiol, and thiolated groups. Based on the results for the orthogonal experimental design, both the ratio of the concentration of iron precursor to polymer and the reaction temperature were the major factors controlling the particle size and its shape morphology. By adjusting the reaction conditions, the iron oxide particle size can be effectively controlled in the range between 2 and 20 nm. The magnetite-based polymer composite was characterized by UV-vis spectroscopy, thermogravimetric analysis, transmission electron microscopy, and X-ray diffraction. Magnetization measurements revealed that the nanocomposite materials exhibit superparamagnetic behavior at room temperature

Preparation and characterization of {omega}-functionalized polystyrene-magnetite nanocomposites

Energy Technology Data Exchange (ETDEWEB)

Jiang Liming [Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027 (China)]. E-mail: cejlm@zju.edu.cn; Sun Weilin [Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Kim, Jungahn [Polymer Hybrids Center, Korea Institute of Science and Technology, Seoul 130-650 (Korea, Republic of)

2007-02-15

Magnetite (Fe{sub 3}O{sub 4}) nanoparticles were prepared by in situ precipitation and oxidation of ferrous ions in the presence of {omega}-functionalized polystyrenes having carboxylate, sulfonate, thiol, and thiolated groups. Based on the results for the orthogonal experimental design, both the ratio of the concentration of iron precursor to polymer and the reaction temperature were the major factors controlling the particle size and its shape morphology. By adjusting the reaction conditions, the iron oxide particle size can be effectively controlled in the range between 2 and 20 nm. The magnetite-based polymer composite was characterized by UV-vis spectroscopy, thermogravimetric analysis, transmission electron microscopy, and X-ray diffraction. Magnetization measurements revealed that the nanocomposite materials exhibit superparamagnetic behavior at room temperature.

Toroidal mesoporous silica nanoparticles (TMSNPs) and related protocells

Science.gov (United States)

Brinker, C. Jeffrey; Lin, Yu-Shen

2018-01-02

In one aspect, the invention provides novel monodisperse, colloidally-stable, toroidal mesoporous silica nanoparticles (TMSNPs) which are synthesized from ellipsoid-shaped mesoporous silica nanoparticles (MSNPs) which are prepared using an ammonia basecatalyzed method under a low surfactant conditions. Significantly, the TMSNPs can be loaded simultaneously with a small molecule active agent, a siRNA, a mRNA, a plasmid and other cargo and can be used in the diagnosis and/or treatment of a variety of disorders, including a cancer, a bacterial infection and/or a viral infection, among others. Related protocells, pharmaceutical compositions and therapeutic and diagnostic methods are also provided.

A co-flow-focusing monodisperse microbubble generator

KAUST Repository

Zhang, Jiaming; Li, Erqiang; Thoroddsen, Sigurdur T

2014-01-01

We use a simple and inexpensive microfluidic device, which is based on microscope glass slides and two tapered glass capillaries, to produce monodisperse microbubbles. The innermost capillary used for transporting the gas is inserted into the second capillary, with its 2 μm sharp tip aligned with the center of the converging-diverging throat of the second capillary. This configuration provides a small and smooth gas flow rate, and a high velocity gradient at the tube outlet. Highly monodisperse microbubbles with diameters ranging from 3.5 to 60 microns have been successfully produced at a rate of up to 40 kHz. A simple scaling law, which is based on the capillary number and liquid-to-gas flow rate ratio, successfully predicts the bubble size. © 2014 IOP Publishing Ltd.

A co-flow-focusing monodisperse microbubble generator

KAUST Repository

Zhang, Jiaming

2014-02-14

We use a simple and inexpensive microfluidic device, which is based on microscope glass slides and two tapered glass capillaries, to produce monodisperse microbubbles. The innermost capillary used for transporting the gas is inserted into the second capillary, with its 2 μm sharp tip aligned with the center of the converging-diverging throat of the second capillary. This configuration provides a small and smooth gas flow rate, and a high velocity gradient at the tube outlet. Highly monodisperse microbubbles with diameters ranging from 3.5 to 60 microns have been successfully produced at a rate of up to 40 kHz. A simple scaling law, which is based on the capillary number and liquid-to-gas flow rate ratio, successfully predicts the bubble size. © 2014 IOP Publishing Ltd.

Synthesis of magnetic CoPt/SiO{sub 2} core-shell nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Seto, Takafumi [Research Consortium for Synthetic Nano-Function Materials Project (SYNAF), National Institute of Advanced Industrial Science and Technology (AIST), Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan); Koga, Kenji [Research Consortium for Synthetic Nano-Function Materials Project (SYNAF), National Institute of Advanced Industrial Science and Technology (AIST), Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan); Takano, Fumiyoshi [Research Consortium for Synthetic Nano-Function Materials Project (SYNAF), National Institute of Advanced Industrial Science and Technology (AIST), Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan); Akinaga, Hiroyuki [Research Consortium for Synthetic Nano-Function Materials Project (SYNAF), National Institute of Advanced Industrial Science and Technology (AIST), Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan); Orii, Takaaki [Research Consortium for Synthetic Nano-Function Materials Project (SYNAF), National Institute of Advanced Industrial Science and Technology (AIST), Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan); Hirasawa, Makoto [Research Consortium for Synthetic Nano-Function Materials Project (SYNAF), National Institute of Advanced Industrial Science and Technology (AIST), Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan); Murayama, Mitsuhiro [National Institute for Material Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan)

2007-04-15

Core-shell nanoparticles composed of ferromagnetic cobalt platinum cores covered by non-magnetic silica shells were synthesized by laser ablating a composite target in a helium background gas. The average diameter of the CoPt core was controlled by adjusting the CoPt/SiO{sub 2} ratio of the ablation target. The particles were also classified in the gas phase using an electrical mobility classifier. The present method successfully synthesized nearly monodispersed nanoparticles with an average core diameter of 2.5nm. This article describes the synthesis of the core-shell nanoparticles and investigates their magnetic properties.

Synthesis of nanoparticles in a flame aerosol reactor with independent and strict control of their size, crystal phase and morphology

International Nuclear Information System (INIS)

Jiang Jingkun; Chen, D-R; Biswas, Pratim

2007-01-01

A flame aerosol reactor (FLAR) was developed to synthesize nanoparticles with desired properties (crystal phase and size) that could be independently controlled. The methodology was demonstrated for TiO 2 nanoparticles, and this is the first time that large sets of samples with the same size but different crystal phases (six different ratios of anatase to rutile in this work) were synthesized. The degree of TiO 2 nanoparticle agglomeration was determined by comparing the primary particle size distribution measured by scanning electron microscopy (SEM) to the mobility-based particle size distribution measured by online scanning mobility particle spectrometry (SMPS). By controlling the flame aerosol reactor conditions, both spherical unagglomerated particles and highly agglomerated particles were produced. To produce monodisperse nanoparticles, a high throughput multi-stage differential mobility analyser (MDMA) was used in series with the flame aerosol reactor. Nearly monodisperse nanoparticles (geometric standard deviation less than 1.05) could be collected in sufficient mass quantities (of the order of 10 mg) in reasonable time (1 h) that could be used in other studies such as determination of functionality or biological effects as a function of size

Synthesis of nanoparticles in a flame aerosol reactor with independent and strict control of their size, crystal phase and morphology

Energy Technology Data Exchange (ETDEWEB)

Jiang Jingkun; Chen, D-R; Biswas, Pratim [Aerosol and Air Quality Research Laboratory, Department of Energy, Environmental and Chemical Engineering, Washington University in St Louis, Campus Box 1180, St Louis, MO 63130 (United States)

2007-07-18

A flame aerosol reactor (FLAR) was developed to synthesize nanoparticles with desired properties (crystal phase and size) that could be independently controlled. The methodology was demonstrated for TiO{sub 2} nanoparticles, and this is the first time that large sets of samples with the same size but different crystal phases (six different ratios of anatase to rutile in this work) were synthesized. The degree of TiO{sub 2} nanoparticle agglomeration was determined by comparing the primary particle size distribution measured by scanning electron microscopy (SEM) to the mobility-based particle size distribution measured by online scanning mobility particle spectrometry (SMPS). By controlling the flame aerosol reactor conditions, both spherical unagglomerated particles and highly agglomerated particles were produced. To produce monodisperse nanoparticles, a high throughput multi-stage differential mobility analyser (MDMA) was used in series with the flame aerosol reactor. Nearly monodisperse nanoparticles (geometric standard deviation less than 1.05) could be collected in sufficient mass quantities (of the order of 10 mg) in reasonable time (1 h) that could be used in other studies such as determination of functionality or biological effects as a function of size.

Polystyrene/Hyperbranched Polyester Blends and Reactive Polystyrene/Hyperbranched Polyester Blends

National Research Council Canada - National Science Library

Mulkern, Thomas

1999-01-01

.... In this work, the incorporation of HBPs in thermoplastic blends was investigated. Several volume fractions of hydroxyl functionalized hyperbranched polyesters were melt blended with nonreactive polystyrene (PS...

''Nonisolated-sensor'' solid polystyrene absorbed dose measurements

International Nuclear Information System (INIS)

Zeitz, L.; Laughlin, J.S.

1982-01-01

A ''nonisolated-sensor'' solid polystyrene calorimeter was constructed to test the role of thermal diffusion in limiting the length of irradiation time during which temperature measurements with nonisolated sensors could be made sufficiently free of drift for determining dose with radiation fields such as gamma rays, x rays, and high-energy electrons. From measured ratios of dose at 5.0 and 0.5 cm in polystyrene and comparisons to dose measurements with a polystyrene parallel-plate (pancake) ion chamber, it was shown that thermal diffusion is sufficiently small in polystyrene to permit accurate measurements for irradiation periods of less than 20 min. Comparison of the absorbed dose measurements and depth dose ratios with pancake ion chambers and calorimeter showed, that within the precision and accuracy of the two measuring systems, there is close agreement. The nonisolated-sensor solid polystyrene calorimeter has the interesting features of (i) simplicity of construction, (ii) simplicity of operation without vacuum or feedback for temperature control, (iii) capability of simultaneous measurements at several depths and off-axis positions, (iv) the very small thermal defect correction with polystyrene, and (v) operation with the calorimeter in any orientation

Nonisolated-sensor solid polystyrene absorbed dose measurements

International Nuclear Information System (INIS)

Zeitz, L.; Laughlin, J.S.

1982-01-01

A nonisolated-sensor solid polystyrene calorimeter was constructed to test the role of thermal diffusion in limiting the length of irradiation time during which temperature measurements with nonisolated sensors could be made sufficiently free of drift for determining dose with radiation fields such as gamma rays, x rays, and high-energy electrons. From measured ratios of dose at 5.0 and 0.5 cm in polystyrene and comparisons to dose measurements with a polystyrene parallel-plate (pancake) ion chamber, it was shown that thermal diffusion is sufficiently small in polystyrene to permit accurate measurements for irradiation periods of less than 20 min. Comparison of the absorbed dose measurements and depth dose ratios with pancake ion chambers and calorimeter showed, that within the precision and accuracy of the two measuring systems, there is close agreement. The nonisolated-sensor solid polystyrene calorimeter has the interesting features of (i) simplicity of construction, (ii) simplicity of operation without vacuum or feedback for temperature control, (iii) capability of simultaneous measurements at several depths and off-axis positions, (iv) the very small thermal defect correction with polystyrene, and (v) operation with the calorimeter in any orientation

Electrosprayed core-shell polymer-lipid nanoparticles for active component delivery

Science.gov (United States)

Eltayeb, Megdi; Stride, Eleanor; Edirisinghe, Mohan

2013-11-01

A key challenge in the production of multicomponent nanoparticles for healthcare applications is obtaining reproducible monodisperse nanoparticles with the minimum number of preparation steps. This paper focus on the use of electrohydrodynamic (EHD) techniques to produce core-shell polymer-lipid structures with a narrow size distribution in a single step process. These nanoparticles are composed of a hydrophilic core for active component encapsulation and a lipid shell. It was found that core-shell nanoparticles with a tunable size range between 30 and 90 nm and a narrow size distribution could be reproducibly manufactured. The results indicate that the lipid component (stearic acid) stabilizes the nanoparticles against collapse and aggregation and improves entrapment of active components, in this case vanillin, ethylmaltol and maltol. The overall structure of the nanoparticles produced was examined by multiple methods, including transmission electron microscopy and differential scanning calorimetry, to confirm that they were of core-shell form.

Application of monodisperse fibers and discs to evaluation of the aerodynamic particle sizer

International Nuclear Information System (INIS)

Hoover, M.D.; Lipowicz, P.J.; Hanson, R.W.; Yeh, H.C.; Casalnuovo, S.A.

1988-01-01

Monodisperse fibers, μm in width and lengths of 5, 10, 20, and 40 μm, as well as monodisperse discs, 2 4 8, or 12 μm in diameter, were prepared using an integrated circuit microchip fabrication technique. Particles were silicon dioxide with thickness of 1 μm. Examination of the particles using a scanning electron microscope showed that they were uniform in shape, with well-defined edges. The particles were suspended in distilled water and aerosolized with a Lovelace nebullizer. The monodisperse particles were used to evaluate the TSI Aerodynamic Particle Sizer (APS). Carbon fibers that were monodisperse in diameter (count median diameter 3.42 μm, geometric standard deviation 1.06) and polydisperse in length (count median length = 28 μm, geometric standard deviation 2.2) were also used. The APS was found to be insensitive to fiber length and only weakly sensitive to disc diameter. (author)

High fluorescence emission of carboxylic acid functionalized polystyrene/BaTiO{sub 3} nanocomposites and rare earth metal complexes: Preparation and characterization

Energy Technology Data Exchange (ETDEWEB)

Cao, X. T.; Showkat, A. M.; Wang, Z.; Lim, K. T., E-mail: ktlim@pknu.ac.kr [Department of Imaging System Engineering, Pukyong National University, Busan 608-737 (Korea, Republic of)

2015-03-30

Noble fluorescence nanocomposite compound based on barium titanate nanoparticles (BTO), polystyrene (PSt), and terbium ion (Tb{sup 3+}) was synthesized by a combination of surface-initiated reversible addition-fragmentation chain transfer (RAFT) polymerization, Friedel-Crafts alkylation reaction and coordinate chemistry. Initially, a modification of surface of BTO was conducted by an exchange process with S-benzyl S’-trimethoxysilylpropyltrithiocarbonate to create macro-initiator for polymerization of styrene. Subsequently, aryl carboxylic acid functionalized polystyrene grafted barium titanate (BTO-g-PSt-COOH) was generated by substitution reaction between 4-(Chloromethyl) benzoic acid and PSt chains. The coordination of the nanohybrids with Tb{sup 3+} ions afforded fluorescent Tb{sup 3+} tagged aryl carboxylic acid functionalized polystyrene grafted barium titanate (BTO-g-PSt-Tb{sup 3+}) complexes. Structure, morphology, and fluorescence properties of nanohybrid complexes were investigated by respective physical and spectral studies. FT-IR and SEM analyses confirmed the formation of BTO-g-PSt-Tb{sup 3+}nanohybrids. Furthermore, TGA profiles demonstrated the grafting of aryl carboxylic acid functionalized polystyrene on BTO surface. Optical properties of BTO-g-PSt-Tb{sup 3+} complexes were investigated by fluorescence spectroscopy.

In vitro placental model optimization for nanoparticle transport studies

Directory of Open Access Journals (Sweden)

Cartwright L

2012-01-01

Full Text Available Laura Cartwright1, Marie Sønnegaard Poulsen2, Hanne Mørck Nielsen3, Giulio Pojana4, Lisbeth E Knudsen2, Margaret Saunders1, Erik Rytting2,51Bristol Initiative for Research of Child Health (BIRCH, Biophysics Research Unit, St Michael's Hospital, UH Bristol NHS Foundation Trust, Bristol, UK; 2University of Copenhagen, Faculty of Health Sciences, Department of Public Health, 3University of Copenhagen, Faculty of Pharmaceutical Sciences, Department of Pharmaceutics and Analytical Chemistry, Copenhagen, Denmark; 4Department of Environmental Sciences, Informatics and Statistics, University Ca' Foscari Venice, Venice, Italy; 5Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston, Texas, USABackground: Advances in biomedical nanotechnology raise hopes in patient populations but may also raise questions regarding biodistribution and biocompatibility, especially during pregnancy. Special consideration must be given to the placenta as a biological barrier because a pregnant woman's exposure to nanoparticles could have significant effects on the fetus developing in the womb. Therefore, the purpose of this study is to optimize an in vitro model for characterizing the transport of nanoparticles across human placental trophoblast cells.Methods: The growth of BeWo (clone b30 human placental choriocarcinoma cells for nanoparticle transport studies was characterized in terms of optimized Transwell® insert type and pore size, the investigation of barrier properties by transmission electron microscopy, tight junction staining, transepithelial electrical resistance, and fluorescein sodium transport. Following the determination of nontoxic concentrations of fluorescent polystyrene nanoparticles, the cellular uptake and transport of 50 nm and 100 nm diameter particles was measured using the in vitro BeWo cell model.Results: Particle size measurements, fluorescence readings, and confocal microscopy indicated both cellular uptake of

Hexagonally ordered nanoparticles templated using a block copolymer film through Coulombic interactions

International Nuclear Information System (INIS)

Lee, Wonjoo; Lee, Seung Yong; Zhang Xin; Rabin, Oded; Briber, R M

2013-01-01

We present a novel and simple method for forming hexagonal gold nanoparticle arrays that uses Coulombic interactions between negatively charged gold nanoparticles on positively charged vertically oriented poly(4-vinylpyridine) cylinders formed in a spin cast polystyrene-b-poly(4-vinylpyridine) block copolymer film. Exposure of the block copolymer film to dibromobutane vapor quaternizes and crosslinks the poly(4-vinylpyridine) domains which allows for the templated deposition of gold nanoparticles into a self-assembled hexagonal array through electrostatic interactions. These systems can form the basis for sensors or next generation nanoparticle based electronics. (paper)

Continuous Flow Controlled Synthesis of Gold Nanoparticles Using Pulsed Mixing Microfluidic System

Directory of Open Access Journals (Sweden)

Guojun Liu

2015-01-01

Full Text Available To prepare the gold nanoparticles (AuNPs with uniform sizes, fine morphology, and good monodispersity, a pulsed mixing microfluidic system based on PZT actuation was presented. The system includes PZT micropump and Y type micromixer. By adjusting voltage (entrance flow rate, pulsed frequency, phase, and other parameters, a variety of mixing modes can be achieved, so as to realize the controllable synthesis of nanoparticles in a certain range. By numerical simulation and analysis, the channel section size, entrance angle, and pulse frequency were optimized. Based on the optimized structure and working parameters, the test prototype has been manufactured in lab, and the related synthesis tests of AuNPs were carried out. The test results indicate that AuNPs with uniform morphology and good monodispersity can be synthesized using the system with the section size (0.4 mm × 0.4 mm, the entrance channel angle (60° under condition of the pulsed frequency (300 Hz, and the entrance flow rate (4 mL/min. The average diameter and its standard deviation of AuNPs synthesized were 21.6 nm, 4.83 nm, respectively. The research work above can be applied to the fields such as the controlled synthesis of noble metal nanoparticles, biomedicine, and microchemical system.

Preparation of gold nanoparticles for plasmonic applications

Energy Technology Data Exchange (ETDEWEB)

Benkovicova, Monika, E-mail: monika.benkovicova@savba.sk [Institute of Physics SAS, Dubravska cesta 9, 845 11 Bratislava (Slovakia); Polymer Institute SAS, Dubravska cesta 9, 845 41 Bratislava (Slovakia); Vegso, Karol; Siffalovic, Peter; Jergel, Matej; Luby, Stefan; Majkova, Eva [Institute of Physics SAS, Dubravska cesta 9, 845 11 Bratislava (Slovakia)

2013-09-30

We present a simple hot injection method for the preparation of colloidal solutions of hydrophobic spherical gold nanoparticles with the diameter around 20 nm and size dispersion below 20%. Various surfactants with different lengths of hydrocarbon chains, such as oleylamine, 1-octadecanethiol, poly (N-vinylpyrrolidone), and AgNO{sub 3} in 1,5-pentanediol, were used for sterical stabilization in the colloidal solution. The hydrodynamic nanoparticle size and size dispersion were determined by the dynamic light scattering (DLS) while the small-angle X-ray scattering (SAXS) from the colloidal solution provided information on the size of the metallic nanoparticle core (without surfactant). Plasmon enhanced resonant absorption peaks between 500 nm and 600 nm were detected by the UV–VIS spectrophotometry. The nanoparticle arrays on silicon prepared by solvent evaporation or Langmuir-Schaefer method were inspected by high-resolution scanning electron microscopy and grazing-incidence SAXS (GISAXS). The presence of side maxima in the GISAXS pattern gives evidence of the nanoparticle ordering by self-assembly while very close values of the interparticle distance derived from GISAXS and the nanoparticle size derived from DLS indicate a close-packed order. - Highlights: ► Preparation of gold nanoparticles by use a various of surfactants ► Preparation of monodisperse nanoparticles ► Characterization of nanoparticles on a solid substrate.

Beneficial effects of microwave-assisted heating versus conventional heating in noble metal nanoparticle synthesis.

Science.gov (United States)

Dahal, Naween; García, Stephany; Zhou, Jiping; Humphrey, Simon M

2012-11-27

An extensive comparative study of the effects of microwave versus conventional heating on the nucleation and growth of near-monodisperse Rh, Pd, and Pt nanoparticles has revealed distinct and preferential effects of the microwave heating method. A one-pot synthetic method has been investigated, which combines nucleation and growth in a single reaction via precise control over the precursor addition rate. Using this method, microwave-assisted heating enables the convenient preparation of polymer-capped nanoparticles with improved monodispersity, morphological control, and higher crystallinity, compared with samples heated conventionally under otherwise identical conditions. Extensive studies of Rh nanoparticle formation reveal fundamental differences during the nucleation phase that is directly dependent on the heating method; microwave irradiation was found to provide more uniform seeds for the subsequent growth of larger nanostructures of desired size and surface structure. Nanoparticle growth kinetics are also markedly different under microwave heating. While conventional heating generally yields particles with mixed morphologies, microwave synthesis consistently provides a majority of tetrahedral particles at intermediate sizes (5-7 nm) or larger cubes (8+ nm) upon further growth. High-resolution transmission electron microscopy indicates that Rh seeds and larger nanoparticles obtained from microwave-assisted synthesis are more highly crystalline and faceted versus their conventionally prepared counterparts. Microwave-prepared Rh nanoparticles also show approximately twice the catalytic activity of similar-sized conventionally prepared particles, as demonstrated in the vapor-phase hydrogenation of cyclohexene. Ligand exchange reactions to replace polymer capping agents with molecular stabilizing agents are also easily facilitated under microwave heating, due to the excitation of polar organic moieties; the ligand exchange proceeds with excellent retention of

Vapor-phase synthesis and characterization of ZnSe nanoparticles

Science.gov (United States)

Sarigiannis, D.; Pawlowski, R. P.; Peck, J. D.; Mountziaris, T. J.; Kioseoglou, G.; Petrou, A.

2002-06-01

Compound semiconductor nanoparticles are an exciting class of materials whose unique optical and electronic properties can be exploited in a variety of applications, including optoelectronics, photovoltaics, and biophotonics. The most common route for synthesizing such nanoparticles has been via liquid-phase chemistry in reverse micelles. This paper discusses a flexible vapor-phase technique for synthesis of crystalline compound semiconductor nanoparticles using gas-phase condensation reactions near the stagnation point of a counterflow jet reactor. ZnSe nanoparticles were formed by reacting vapors of dimethylzinc: triethylamine adduct and hydrogen selenide at 120Torr and room temperature (28°C). No attempt was made to passivate the surface of the particles, which were collected as random aggregates on silicon wafers or TEM grids placed downstream of the reaction zone. Particle characterization using TEM, electron diffraction, Raman and EDAX revealed that the aggregates consisted of polycrystalline ZnSe nanoparticles, almost monodisperse in size (with diameters of ~40nm). The polycrystalline nanoparticles appear to have been formed by coagulation of smaller single-crystalline nanoparticles with characteristic size of 3-5 run.

Electrosprayed core–shell polymer–lipid nanoparticles for active component delivery

International Nuclear Information System (INIS)

Eltayeb, Megdi; Edirisinghe, Mohan; Stride, Eleanor

2013-01-01

A key challenge in the production of multicomponent nanoparticles for healthcare applications is obtaining reproducible monodisperse nanoparticles with the minimum number of preparation steps. This paper focus on the use of electrohydrodynamic (EHD) techniques to produce core–shell polymer–lipid structures with a narrow size distribution in a single step process. These nanoparticles are composed of a hydrophilic core for active component encapsulation and a lipid shell. It was found that core–shell nanoparticles with a tunable size range between 30 and 90 nm and a narrow size distribution could be reproducibly manufactured. The results indicate that the lipid component (stearic acid) stabilizes the nanoparticles against collapse and aggregation and improves entrapment of active components, in this case vanillin, ethylmaltol and maltol. The overall structure of the nanoparticles produced was examined by multiple methods, including transmission electron microscopy and differential scanning calorimetry, to confirm that they were of core–shell form. (paper)

Biosynthesis of size-controlled gold nanoparticles using fungus, Penicillium sp.

Science.gov (United States)

Zhang, Xiaorong; He, Xiaoxiao; Wang, Kemin; Wang, Yonghong; Li, Huimin; Tan, Weihong

2009-10-01

The unique optoelectronic and physicochemical properties of gold nanoparticles are significantly dependent on the particle size, shape and structure. In this paper, biosynthesis of size-controlled gold nanoparticles using fungus Penicillium sp. is reported. Fungus Penicillium sp. could successfully bioreduce and nucleate AuCl4(-) ions, and lead to the assembly and formation of intracellular Au nanoparticles with spherical morphology and good monodispersity after exposure to HAuCl4 solution. Reaction temperature, as an important physiological parameter for fungus Penicillium sp. growth, could significantly control the size of the biosynthesized Au nanoparticles. The biological compositions and FTIR spectra analysis of fungus Penicillium sp. exposed to HAuCl4 solution indicated the intracellular reducing sugar played an important role in the occurrence of intracellular reduction of AuCl4(-) ions and the growth of gold nanoparticles. Furthermore, the intracellular gold nanoparticles could be easily separated from the fungal cell lysate by ultrasonication and centrifugation.

High-speed monodisperse droplet generation by ultrasonically controlled micro-jet breakup

Science.gov (United States)

Frommhold, Philipp Erhard; Lippert, Alexander; Holsteyns, Frank Ludwig; Mettin, Robert

2014-04-01

A liquid jet that is ejected from a nozzle into air will disintegrate into drops via the well-known Plateau-Rayleigh instability within a certain range of Ohnesorge and Reynolds numbers. With the focus on the micrometer scale, we investigate the control of this process by superimposing a suitable ultrasonic signal, which causes the jet to break up into a very precise train of monodisperse droplets. The jet leaves a pressurized container of liquid via a small orifice of about 20 μm diameter. The break-up process and the emerging droplets are recorded via high-speed imaging. An extended parameter study of exit speed and ultrasonic frequency is carried out for deionized water to evaluate the jet's state and the subsequent generation of monodisperse droplets. Maximum exit velocities obtained reach almost 120 m s-1, and frequencies have been applied up to 1.8 MHz. Functionality of the method is confirmed for five additional liquids for moderate jet velocities 38 m s-1. For the uncontrolled jet disintegration, the drop size spectra revealed broad distributions and downstream drop growth by collision, while the acoustic control generated monodisperse droplets with a standard deviation less than 0.5 %. By adjustment of the acoustic excitation frequency, drop diameters could be tuned continuously from about 30 to 50 μm for all exit speeds. Good agreement to former experiments and theoretical approaches is found for the relation of overpressure and jet exit speed, and for the observed stability regions of monodisperse droplet generation in the parameter plane of jet speed and acoustic excitation frequency. Fitting of two free parameters of the general theory to the liquids and nozzles used is found to yield an even higher precision. Furthermore, the high-velocity instability limit of regular jet breakup described by von Ohnesorge has been superseded by more than a factor of two without entering the wind-induced instability regime, and monodisperse droplet generation was

New nanocomposites of polystyrene with polyaniline doped with lauryl sulfuric acid

Science.gov (United States)

Pud, A. A.; Nikolayeva, O. A.; Vretik, L. O.; Noskov, Yu. V.; Ogurtsov, N. A.; Kruglyak, O. S.; Fedorenko, E. A.

2017-08-01

This work is concentrated on synthesis and investigation of new core-shell nanocomposites of polystyrene (PS) with doped polyaniline (PANI). The latex containing PS nanoparticles with sizes of 15-30 nm was prepared by microemulsion polymerization of styrene in water media. The PS/PANI nanocomposites were synthesized by chemical oxidative polymerization of aniline in the PS latex media in a presence of lauryl sulfuric acid (LSA), which served as both dopant and plasticizer. The real content of PANI in the synthesized nanocomposites was determined by UV-Vis spectroscopy method. The composition of the nanocomposites and oxidation state of the doped polyaniline were characterized by FTIR spectroscopy. The core-shell morphology of the nanocomposite nanoparticles was proved by transmission and scanning electron microscopy. It was found that conductivity and thermal behavior in air of these nanocomposites not only nonlinearly depended on the doped polyaniline content but also were strongly effected both by plasticizing properties of the acid-dopant and presence of the polyaniline shell. A possibility of application of these nanocomposites as sensor materials has been demonstrated.

The relationship between the Tg depression and the speeding up of physical aging in polystyrene/gold nanocomposites

Science.gov (United States)

Boucher, Virginie M.; Cangialosi, Daniele; Alegria, Angel; Colmenero, Juan

2011-03-01

The effect of gold nanoparticles on the segmental dynamics, glass transition (Tg) and physical aging of polystyrene (PS) was studied in PS/Gold nanocomposites samples containing 5 and 15 wt.% of 60 nm spherical gold nanoparticles, surface-treated with thiolated-PS. While the segmental dynamics of PS, as assessed by broadband dielectric spectroscopy (BDS), was found to be unchanged in presence of gold nanoparticles, the calorimetric Tg of PS was shown to decrease with increasing the amount of nanoparticles in the samples. Furthermore, the physical aging of PS, monitored by measuring the enthalpy relaxation below Tg by means of DSC, was shown to speed up with increasing the nanoparticles weight fraction, i.e. the amount of PS/Gold interface in the hybrid material. Thus, the main conclusion of our work is that PS molecular mobility and out-of-equilibrium dynamics are decoupled in these nanocomposites. The significant effect of the amount of PS/Gold interface on both the physical aging rate of PS and the calorimetric Tg depression are quantitatively accounted for by a model based on the diffusion of free volume holes towards polymer interfaces, with a diffusion coefficient depending only on the molecular mobility.

Study of mass transfer in artificial biofilm to enhance prodn. with immobilized microorganism

NARCIS (Netherlands)

Beuling, E.E.; Ottengraf, S.P.P.; Heuvel, van den J.C.

1994-01-01

To study the effect of the cell fraction f on diffusion an artificial biofilm was developed, consisting of an agar matrix contg. monodisperse impenetrable polystyrene particles with the same diam. as bacteria (1 mm). Diffusion of glucose at different polystyrene fractions was measured in two ways:

Optical nanoparticles: synthesis and biomedical application

International Nuclear Information System (INIS)

Nhung Tran, Hong; Lien Nghiem, Thi Ha; Duong Vu, Thi Thuy; Ha Chu, Viet; Hoa Do, Quang; Vu, Duong; Nghia Nguyen, Trong; Tan Pham, Minh; Son Vu, Van; Nguyen, Thi Thuy; Ngoc Nguyen, Thi Bich; Duc Tran, Anh; Trinh, Thi Thuong; Huan Le, Quang; Thuan Tong, Kim; Thuy Tran, Thanh; Hoang, Thi My Nhung; Thanh Nguyen, Lai; Nguyen Duong, Cao; Minh Pham, Duc

2015-01-01

This paper presents a summary of our results on studies of synthesis and biomedical application of optical nanoparticles. Gold, dye-doped silica based and core–shell multifunctional multilayer (SiO_2/Au, Fe_3O_4/SiO_2, Fe_3O_4/SiO_2/Au) water-monodispersed nanoparticles were synthesized by chemical route and surface modified with proteins and biocompatible chemical reagents. The particles were conjugated with antibody or aptamer for specific detecting and imaging bacteria and cancer cells. The photothermal effects of gold nanoshells (SiO_2/Au and Fe_3O_4/SiO_2/Au) on cells and tissues were investigated. The nano silver substrates were developed for surface enhanced Raman scattering (SERS) spectroscopy to detect melamine. (review)

Assessment of morphology, topography and chemical composition of water-repellent films based on polystyrene/titanium dioxide nanocomposites

Science.gov (United States)

Bolvardi, Beleta; Seyfi, Javad; Hejazi, Iman; Otadi, Maryam; Khonakdar, Hossein Ali; Drechsler, Astrid; Holzschuh, Matthias

2017-02-01

In this study, polystyrene (PS)/titanium dioxide (TiO2) films were fabricated through simple solution casting technique via a modified phase separation process. The presented approach resulted in a remarkable reduction in the required amount of nanoparticles for achieving superhydrophobicity. Scanning electron microscopy (SEM) and 3D confocal microscopy were utilized to characterize surface morphology and topography of samples, respectively. An attempt was made to give an in-depth analysis on the surface rough structure using 3D roughness profiles. It was found that high inclusions of non-solvent and nanoparticles resulted in a stable self-cleaning behavior due to the strong presence of hydrophobic TiO2 nanoparticles on the surface. Quite unexpectedly, low inclusions of nanoparticles and non-solvent also resulted in superhydrophobic property mainly due to the proper level of induced surface roughness. XPS analysis was also utilized to determine the chemical composition of the films' surfaces. The results of falling drop experiments showed that the sample containing a higher level of nanoparticles had a much lower mechanical resistance against the induced harsh conditions. All in all, the presented method has shown promising potential in fabrication of superhydrophobic surfaces with self-cleaning behavior using the lowest content of nanoparticles.

Water-dispersible small monodisperse electrically conducting antimony doped tin oxide nanoparticles

Czech Academy of Sciences Publication Activity Database

Peters, K.; Zeller, P.; Štefanić, G.; Skoromets, Volodymyr; Němec, Hynek; Kužel, Petr; Fattakhova-Rohlfing, D.

2015-01-01

Roč. 27, č. 3 (2015), 1090-1099 ISSN 0897-4756 R&D Projects: GA ČR GA13-12386S Grant - others:AVČR(CZ) M100101218 Institutional support: RVO:68378271 Keywords : conducting nanoparticles * electrical conductivity * charge transport Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 9.407, year: 2015

Synthetic Polymers at Interfaces: Monodisperse Emulsions Multiple Emulsions and Liquid Marbles

Science.gov (United States)

Sun, Guanqing

discussion of emulsion stabilization and preparation. A historical review of multiple emulsions is presented subsequently and the stability mechanism is discussed in details with regard to the transportation kinetics of small molecules through the separating membrane of double emulsions. The principle, property and applications of liquid marbles are then summarized. Secondly, the preparation of monodisperse Pickering emulsions stabilized by soft PNIPAM-co-MAA microgels through SPG membrane emulsification is described. The influence of the membrane pore size, pH of the particle dispersion, particle size and the operating parameters of the membrane emulsification device on the size of the emulsion droplets was investigated systematically. The improvement in monodispersity of the emulsion droplets allows us to measure the release profiles of a small molecular dye and a larger nanoparticle through the colloidosomes. It is further demonstrated that the preparation of monodisperse emulsions stabilized by other types of soft particles allows us control the stability of the emulsion with a pH trigger and improved biocompatibility. Thirdly, the preparation of multiple emulsions stabilized by a special designed PEG-b-PS diblock copolymer with desired hydrophobicity by one-step method was presented. The ultra-stability of the as-obtained multiple emulsions was ascribed to the effective steric stabilization of the two interfaces with different polymer configurations at the interfaces. A series of diblock copolymer with increasing PS chain length was then synthesized to investigate the influence of asymmetry ratio on the type of emulsions prepared. It is found that the diblock copolymers with the asymmetry ratio of approximately 1 had the highest power to stabilize multiple emulsions. The multiple emulsions were demonstrated to be a promising platform for controlled release. In the end, particle-stabilized water-in-air liquid marbles were investigated. PSco-MAA nanoparticles synthesized

Copper nanoparticles synthesis by gamma irradiation in chitosan aqueous system

International Nuclear Information System (INIS)

Shahrul Izwan Ahmad; Md Soot Ahmad; Shahidan Radiman

2009-01-01

A study on effect of chitosan concentration on the copper nanoparticles synthesis using gamma irradiation as source of reducing agent has been done at total absorbed dose of 50 kGy. The addition of ethanol is vital as scavenger of oxidation radical that eliminate the function of reducing agent produced by radiolysis process of gamma ray in water system. Transmission electron microscopy observations show the formation of copper nanoparticles embedded in chitosan matrix. As the concentration of chitosan increase the solution become darker and nanoparticles produced are densely, in order form with polydisperse size. While at the low concentration of chitosan, the color of solution become more reddish and the particles produced are monodisperse in size with regular shape and more orderly. The phase of pure copper nanoparticles embedded in the chitosan matrix was confirmed by X-ray diffraction. (Author)

Responsive Block Copolymer and Gold Nanoparticle Hybrid Nanotubes.

Science.gov (United States)

Chang, Sehoon; Singamaneni, Srikanth; Young, Seth; Tsukruk, Vladimir

2009-03-01

We demonstrate the facile fabrication of responsive polymer and metal nanoparticle composite nanotube structures. The nanotubes are comprised of responsive block copolymer, polystyrene-block-poly (2-vinylpyridine) (PS-b-P2VP), and gold nanoparticles. PS-b-P2VP nanotubes were fabricated using porous alumina template and in situ reduction of the gold nanoparticles in P2VP domains. Owing to the pH sensitive nature of P2VP (anionic polymer with a pKa of 3.8), the nanotubes exhibit a dramatic change in topology in response to the changes in the external pH. Furthermore, the gold nanoparticles in the responsive block exhibit a reversible aggregation, causing a reversible change in optical properties such as absorption.

Diffusive dynamics of nanoparticles in aqueous dispersions

KAUST Repository

He, Kai; Spannuth, Melissa; Conrad, Jacinta C.; Krishnamoorti, Ramanan

2012-01-01

The diffusive dynamics of 100 nm to 400 nm diameter polystyrene nanoparticles dispersed in water were studied using brightfield and fluorescence based differential dynamic microscopy (DDM) and compared to those obtained from dynamic light scattering. The relaxation times measured with brightfield and fluorescence DDM over a broad range of concentration of nanoparticles (10 -6 ≤ φ ≤ 10-3) and scattering vectors (0.5 μm-1 < q < 10 μm-1) are in excellent agreement with each other and extrapolate quantitatively to those obtained from DLS measurements. The diffusion coefficients extracted from the q-dependent relaxation times using all three methods are independent of the nanoparticle concentration. © 2012 The Royal Society of Chemistry.

Synthesis of 1 nm Pd Nanoparticles in a Microfluidic Reactor: Insights from in Situ X ray Absorption Fine Structure Spectroscopy and Small-Angle X ray Scattering

Energy Technology Data Exchange (ETDEWEB)

Karim, Ayman M.; Al Hasan, Naila M.; Ivanov, Sergei A.; Siefert, Soenke; Kelly, Ryan T.; Hallfors, Nicholas G.; Benavidez, Angelica D.; Kovarik, Libor; Jenkins, Aaron; Winans, R. E.; Datye, Abhaya K.

2015-06-11

In this paper we show that the temporal separation of nucleation and growth is not a necessary condition for the colloidal synthesis of monodisperse nanoparticles. The synthesis mechanism of Pd nanoparticles was determined by in situ XAFS and SAXS in a microfluidic reactor capable of millisecond up to an hour time resolution. The SAXS results showed two autocatalytic growth phases, a fast growth phase followed by a very slow growth phase. The steady increase in the number of particles throughout the two growth phases indicates the synthesis is limited by slow continuous nucleation. The transition from fast to slow growth was caused by rapid increase in bonding with the capping agent as shown by XAFS. Based on this fundamental understanding of the synthesis mechanism, we show that 1 nm monodisperse Pd nanoparticles can be synthesized at low temperature using a strong binding capping agent such as trioctylphosphine (TOP).

The preparation of highly active antimicrobial silver nanoparticles by an organometallic approach

International Nuclear Information System (INIS)

Fernandez, Eduardo J; Garcia-Barrasa, Jorge; Lopez-de-Luzuriaga, Jose M; Monge, Miguel; Laguna, Antonio; Torres, Carmen

2008-01-01

Silver nanoparticles of small size with a high surface to volume ratio have been prepared using an organometallic approach. For this, the complex NBu 4 [Ag(C 6 F 5 ) 2 ] has been treated with AgClO 4 in a 1:1 molar ratio, giving rise to the nanoparticle precursor [Ag(C 6 F 5 )] in solution. Addition of one equivalent of hexadecylamine (HDA) and 5 h of reflux in toluene leads to a deep yellow solution containing monodisperse silver nanoparticles (Ag NPs) of ca. 10 nm. This approach leads to nanoparticles with almost uncontaminated surfaces which make them very reactive. Antimicrobial studies show that these nanoparticles are very active as antimicrobial agents. Very low concentrations between 12 and 25 μg ml -1 of Ag NPs are enough to produce bacteriostatic and bactericidal effectiveness

Effect of Nanoparticle Core Size on Polymer-Coated Gold Nanoparticle Location in Block Copolymers

Science.gov (United States)

Petrie, J. D.; Fredrickson, G. H.; Kramer, E. J.

2009-03-01

Gold nanoparticles modified by short chain polymer thiols [Au-PS] can be designed to strongly localize either in the PS domains of a polystyrene-b-poly(2-vinylpyridine) [PS-PVP] block copolymer or at the interface. The P2VP block has a stronger attractive interaction with bare gold than the PS block. Thus, when the areal chain density σ of end-attached PS chains falls below a critical areal chain density σc the Au-PS nanoparticles adsorb to the PS-b-P2VP interface. The effect of the polymer ligand molecular weight on the σc has been shown to scale as σc˜ ((R + Rg)/(R*Rg))̂2, where R is the curvature of the Au nanoparticle core radius. To test this scaling relation for σc further we are synthesizing gold nanoparticles with different core radii and will present preliminary results on σc as a function of R.

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

International Nuclear Information System (INIS)

Ngoi, Kuan Hoon; Chia, Chin-Hua; Zakaria, Sarani; Chiu, Wee Siong

2015-01-01

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 spherical and cubic nanoparticles, which are 36 emu/g and 37 emu/g respectively and superparamagnetic in nature

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

Energy Technology Data Exchange (ETDEWEB)

Ngoi, Kuan Hoon; Chia, Chin-Hua, E-mail: chia@ukm.edu.my; Zakaria, Sarani [School of Applied Physics, Faculty Science and Technology, University Kebangsaan Malaysia 43600 UKM Bangi, Selangor (Malaysia); Chiu, Wee Siong [Low Dimensional Materials Research Centre, Department of Physics, Faculty of Science, University of Malaya, 50603 Lembah Pantai, Kuala Lumpur (Malaysia)

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 spherical and cubic nanoparticles, which are 36 emu/g and 37 emu/g respectively and superparamagnetic in nature.

Synthesis and characterization of chemically ordered FePt magnetic nano-particles

Energy Technology Data Exchange (ETDEWEB)

Srinivasa Rao, K. [Centre for Materials for Electronics Technology (C-MET), IDA phase-III, Cherlapally, Hyderabad 500 051 (India); Balaji, T., E-mail: theerthambalaji@yahoo.co [Centre for Materials for Electronics Technology (C-MET), IDA phase-III, Cherlapally, Hyderabad 500 051 (India); Lingappa, Y. [Department of Chemistry, Sri Venkateswara University, Tirupati 517 502 (India); Reddy, M.R.P.; Kumar, Arbind; Prakash, T.L. [Centre for Materials for Electronics Technology (C-MET), IDA phase-III, Cherlapally, Hyderabad 500 051 (India)

2010-08-15

Monodispersed FePt alloy magnetic nano-particles are prepared by reduction of platinum acetyl acetonate and iron acetyl acetonate salts together in the presence of oleic acid and oleyl amine stabilizers by polyol process. The particle size of FePt is in the range of 2-3 nm confirmed by transmission electron microscopy (TEM). As-synthesized FePt nano-particles are chemically disordered with face centre cubic (fcc) structure where as after vacuum annealing these particles changed to face centre tetragonal (fct) ordered structure confirmed by the X-ray diffraction technique. Magnetic coercivity of 5.247 KOe was observed for fct structure.

In vivo integrity of polymer-coated gold nanoparticles

Science.gov (United States)

Kreyling, Wolfgang G.; Abdelmonem, Abuelmagd M.; Ali, Zulqurnain; Alves, Frauke; Geiser, Marianne; Haberl, Nadine; Hartmann, Raimo; Hirn, Stephanie; de Aberasturi, Dorleta Jimenez; Kantner, Karsten; Khadem-Saba, Gülnaz; Montenegro, Jose-Maria; Rejman, Joanna; Rojo, Teofilo; de Larramendi, Idoia Ruiz; Ufartes, Roser; Wenk, Alexander; Parak, Wolfgang J.

2015-07-01

Inorganic nanoparticles are frequently engineered with an organic surface coating to improve their physicochemical properties, and it is well known that their colloidal properties may change upon internalization by cells. While the stability of such nanoparticles is typically assayed in simple in vitro tests, their stability in a mammalian organism remains unknown. Here, we show that firmly grafted polymer shells around gold nanoparticles may degrade when injected into rats. We synthesized monodisperse radioactively labelled gold nanoparticles (198Au) and engineered an 111In-labelled polymer shell around them. Upon intravenous injection into rats, quantitative biodistribution analyses performed independently for 198Au and 111In showed partial removal of the polymer shell in vivo. While 198Au accumulates mostly in the liver, part of the 111In shows a non-particulate biodistribution similar to intravenous injection of chelated 111In. Further in vitro studies suggest that degradation of the polymer shell is caused by proteolytic enzymes in the liver. Our results show that even nanoparticles with high colloidal stability can change their physicochemical properties in vivo.

Targeting and molecular imaging of HepG2 cells using surface-functionalized gold nanoparticles

International Nuclear Information System (INIS)

Rathinaraj, Pierson; Lee, Kyubae; Choi, Yuri; Park, Soo-Young; Kwon, Oh Hyeong; Kang, Inn-Kyu

2015-01-01

Mercaptosuccinic acid (M)-conjugated gold nanoparticles (GM) were prepared and characterized by transmission electron microscope and dynamic light scattering. M was used to improve the monodispersity and non-specific intracellular uptake of nanoparticles. Lactobionic acid (L) was subsequently conjugated to the GM to target preferentially HepG2 cells (liver cancer cells) that express asialoglycoprotein receptors (ASGPR) on their membrane surfaces and facilitate the transit of nanoparticles across the cell membrane. The mean size of lactobionic acid-conjugated gold nanoparticle (GL) was approximately 10 ± 0.2 nm. Finally, the Atto 680 dye (A6) was coupled to the nanoparticles to visualize their internalization into HepG2 cells. The interaction of surface-modified gold nanoparticles with HepG2 cells was studied after culturing cells in media containing the GM or L-conjugated GM (GL)

Targeting and molecular imaging of HepG2 cells using surface-functionalized gold nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Rathinaraj, Pierson [Auckland University of Technology, Institute of Biomedical Technologies (New Zealand); Lee, Kyubae; Choi, Yuri; Park, Soo-Young [Kyungpook National University, School of Applied Chemical Engineering, Graduate School (Korea, Republic of); Kwon, Oh Hyeong [Kumoh National Institute of Technology, Department of Polymer Science and Engineering (Korea, Republic of); Kang, Inn-Kyu, E-mail: ikkang@knu.ac.kr [Kyungpook National University, School of Applied Chemical Engineering, Graduate School (Korea, Republic of)

2015-07-15

Mercaptosuccinic acid (M)-conjugated gold nanoparticles (GM) were prepared and characterized by transmission electron microscope and dynamic light scattering. M was used to improve the monodispersity and non-specific intracellular uptake of nanoparticles. Lactobionic acid (L) was subsequently conjugated to the GM to target preferentially HepG2 cells (liver cancer cells) that express asialoglycoprotein receptors (ASGPR) on their membrane surfaces and facilitate the transit of nanoparticles across the cell membrane. The mean size of lactobionic acid-conjugated gold nanoparticle (GL) was approximately 10 ± 0.2 nm. Finally, the Atto 680 dye (A6) was coupled to the nanoparticles to visualize their internalization into HepG2 cells. The interaction of surface-modified gold nanoparticles with HepG2 cells was studied after culturing cells in media containing the GM or L-conjugated GM (GL)

Technical Note: Effect of Incorporating Expanded Polystyrene ...

African Journals Online (AJOL)

Incorporating expanded polystyrene granules in concrete matrix can produce lightweight polystyrene aggregate concrete of various densities. Workability which is an important property of concrete, aects the rate of placement and the degree of compaction of concrete. Inadequate compaction leads to reduction in both ...

Investigation of optical properties of aluminium oxide doped polystyrene polymer nanocomposite films

Science.gov (United States)

Bhavsar, Shilpa; Patel, Gnansagar B.; Singh, N. L.

2018-03-01

In the present work, a simple solution casting method was utilized to synthesize aluminium oxide (Al2O3) doped polystyrene (PS) polymer nanocomposite films. As synthesized films were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, ultra violet (UV)-visible spectroscopy, photoluminescence (PL) method and scanning electron microscopy (SEM). The crystalline nature of the films was found to decrease after incorporation of filler in the polymer matrix as revealed by XRD results. A new carbonyl group was appeared in the FTIR spectra and confirmed the charge transfer reaction between filler and polymer matrix. The decrease in the band gap was found with the filler concentration in the synthesized polymer nanocomposite films. Photoluminescence emission spectra of nanocomposites were observed at 411 nm, 435 nm and 462 nm, respectively in violet-blue region which indicates interaction between the dopant and the polymer matrix. The PL emission spectra of polymer nanocomposite films with 3 wt% of Al2O3 filler exhibited higher peak intensity. The Al2O3 filler dispersion is found to reduce band gap and promote luminescence property in polystyrene. SEM analysis indicates the agglomeration of Al2O3 nanoparticles into PS matrix at higher concentration.

Preparation of submicrometer monodispersed magnetic silica particles using a novel water in oil microemulsion: properties and application for enzyme immobilization.

Science.gov (United States)

Tuttolomondo, Maria Victoria; Villanueva, Maria Emilia; Alvarez, Gisela Solange; Desimone, Martín Federico; Díaz, Luis Eduardo

2013-10-01

The synthesis of monodispersed magnetic silica nanoparticles (MSN) is described using a water-in-oil reverse microemulsion system that does not require the use of co-surfactants. Sodium silicate, Tween 20 as a neutral surfactant and 1-butanol as the organic phase were used. There are several advantages of the proposed method including a saturation magnetization value of 10 emu/g for the particles obtained, uniformity of size and that they are easily functionalized to bind urease covalently. Moreover, the intra-day, inter-day and long-term stability results confirm that the procedure was successful and the enzyme-linked MSNs were stable over repeated uses and storage retaining more than 75% activity after 4 months.

Immobilizing LaFeO_3 nanoparticles on carbon spheres for enhanced heterogeneous photo-Fenton like performance

International Nuclear Information System (INIS)

Wang, Kaixuan; Niu, Helin; Chen, Jingshuai; Song, Jiming; Mao, Changjie; Zhang, Shengyi; Gao, Yuanhao

2017-01-01

Highlights: • LaFeO_3 nanoparticles sub–10 nm were successfully immobilized on monodisperse carbon spheres for the first time through a facile and environmental friendly ultrasonic assisted surface ions adsorption method. • LaFeO_3/C nanocomposite exhibits much higher photo-Fenton like catalytic activity than LaFeO_3. • The superior property was attributed to the synergistic effects from the photo-Fenton like process and the presence of monodisperse carbon spheres. - Abstract: LaFeO_3 nanoparticles immobilized on the surface of monodisperse carbon spheres have been obtained through a facile and environmentally friendly ultrasonic assisted surface ions adsorption method. The LaFeO_3/C nanocomposite was evaluated as photo-Fenton like catalyst for the degradation of Rhodamine B (RhB) under visible light irradiation (λ > 420 nm). The LaFeO_3/C nanocomposite possesses high specific surface area compared with pure LaFeO_3 and significantly enhanced photo-Fenton like catalytic performance. The possible formation process of the LaFeO_3/C nanocomposite and the mechanism for photo-Fenton like reaction were discussed. The superior property was attributed to the synergistic effects from the photo-Fenton like process and the presence of carbon spheres. In addition, the heterogeneous process led to better recyclability of this type of catalyst.

Syringe-vacuum microfluidics: A portable technique to create monodisperse emulsions.

Science.gov (United States)

Abate, Adam R; Weitz, David A

2011-03-16

We present a simple method for creating monodisperse emulsions with microfluidic devices. Unlike conventional approaches that require bulky pumps, control computers, and expertise with device physics to operate devices, our method requires only the microfluidic device and a hand-operated syringe. The fluids needed for the emulsion are loaded into the device inlets, while the syringe is used to create a vacuum at the device outlet; this sucks the fluids through the channels, generating the drops. By controlling the hydrodynamic resistances of the channels using hydrodynamic resistors and valves, we are able to control the properties of the drops. This provides a simple and highly portable method for creating monodisperse emulsions.

Preparation and characterization of poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) composite thin films highly loaded with platinum nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Chang, Chao-Ching, E-mail: ccchang@tku.edu.tw [Department of Chemical and Materials Engineering, Tamkang University, No. 151, Yingzhuan Rd., Danshui Dist., New Taipei City 25137, Taiwan (China); Energy and Opto-Electronic Materials Research Center, Tamkang University, No. 151, Yingzhuan Rd., Danshui Dist., New Taipei City 25137, Taiwan (China); Jiang, Ming-Tai [Department of Chemical and Materials Engineering, Tamkang University, No. 151, Yingzhuan Rd., Danshui Dist., New Taipei City 25137, Taiwan (China); Chang, Chen-Liang; Lin, Cheng-Lan [Department of Chemical and Materials Engineering, Tamkang University, No. 151, Yingzhuan Rd., Danshui Dist., New Taipei City 25137, Taiwan (China); Energy and Opto-Electronic Materials Research Center, Tamkang University, No. 151, Yingzhuan Rd., Danshui Dist., New Taipei City 25137, Taiwan (China)

2011-06-15

Research highlights: {yields} Nano-sized and mono-dispersed Pt nanoparticles were synthesized by a polyol method. {yields} A thin film of PEDOT:PSS loaded with high concentration of Pt nanoparticles has been prepared. {yields} The PEDOT:PSS-Pt modified electrode has good potential to serve as a counter electrode in DSSC. - Abstract: In this work, we propose a simple and efficient, low-temperature ({approx}120 deg. C) process to prepare transparent thin films of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) loaded with high concentration (up to 22.5 wt%) of platinum (Pt) nanoparticles. Firstly, an improved polyol method was modified to synthesize nano-sized ({approx}5 nm) and mono-dispersed Pt particles. These nanoparticles were incorporated into the matrix of PEDOT:PSS thin films via a spin coating/drying procedure. The electrochemical activities of the PEDOT:PSS thin film modified electrodes with respect to the I{sup -}/I{sub 3}{sup -} redox reactions were investigated. It was found that the modified electrode of PEDOT:PSS thin film containing 22.5 wt% Pt exhibited the electrochemical activity comparable to the conventional Pt thin film electrode, suggesting that this electrode has good potential to serve as a counter electrode in dye-sensitized solar cells.

Formation of wrinkles on graphene induced by nanoparticles: atomic force microscopy study

Czech Academy of Sciences Publication Activity Database

Pacáková, Barbara; Vejpravová, Jana; Repko, A.; Mantlíková, Alice; Kalbáč, Martin

2015-01-01

Roč. 95, Dec (2015), s. 573-579 ISSN 0008-6223 R&D Projects: GA ČR(CZ) GA15-01953S; GA MŠk 7E12057 EU Projects: European Commission(XE) 262943 - MULTIFUN Institutional support: RVO:68378271 ; RVO:61388955 Keywords : graphene * monodisperse nanoparticles * wrinkles * AFM Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 6.198, year: 2015

Study of dithiol monolayer as the interface for controlled deposition of gold nanoparticles

International Nuclear Information System (INIS)

Cichomski, M.; Tomaszewska, E.; Kosla, K.; Kozlowski, W.; Kowalczyk, P.J.; Grobelny, J.

2011-01-01

Self-assembled monolayer of dithiol molecules, deposited on polycrystalline Au (111), prepared at room atmosphere, was studied using scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). Dithiols were used as interface, which chemically bonds to the deposited gold nanoparticles through strong covalent bonds. The size and size distribution of the deposited nanoparticles were measured using dynamic light scattering (DLS), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The AFM results showed that nanoparticles are immobilized and stable during scanning procedure and do not contaminate the AFM tip. The size of monodisperse nanoparticles obtained from the DLS measurements is slightly higher than that obtained from the AFM and SEM measurements. This is due to the fact that the DLS measures the hydrodynamic radius, dependent on the protective chemical layer on nanoparticles. - Research Highlights: → Dithiols molecules create chemically bounded layers on a Au (111) surface. → Gold nanoparticles can be chemically bounded to a self-assembled monolayer. → Nanoparticles are stable during AFM probe interactions.

Convenient preparation of ITO nanoparticles inks for transparent conductive thin films

International Nuclear Information System (INIS)

Ito, Daisuke; Masuko, Keiichiro; Weintraub, Benjamin A.; McKenzie, Lallie C.; Hutchison, James E.

2012-01-01

Tin-doped indium oxide (ITO) nanoparticles are useful precursors to transparent electrodes in a variety of technologically important applications. We synthesized ITO nanoparticles from indium and tin acetylacetonates in oleyl alcohol using a novel temperature ramp profile. The monodispersed ITO nanoparticles have an average diameter of 8.6 nm and form dense, flat films by simple spin coating. The thickness of the film can be controlled by varying the number of additional depositions. The resulting ITO film is transparent and has a resistivity of 7 × 10 −3 Ω cm after sintering at 300 °C. Using a suitable solvent, it is possible to coat high-aspect-ratio structures with ITO nanoparticles. This approach to ITO coatings is greener and offers a number of advantages for transparent electrodes because it is highly versatile, easily scalable, and supports low-cost manufacturing.

Polystyrene calorimeter for electron beam dose measurements

DEFF Research Database (Denmark)

Miller, A.

1995-01-01

Calorimeters from polystrene have been constructed for dose measurement at 4-10 MeV electron accelerators. These calorimeters have been used successfully for a few years, and polystyrene calorimeters for use at energies down to 1 MeV and being tested. Advantage of polystyrene as the absorbing...

Oxide nanoparticle-based fabrication and optical properties of Cu(In{sub 1−x}Ga{sub x})S{sub 2} absorber layer for solar cells

Energy Technology Data Exchange (ETDEWEB)

Choi, Yo-Min [Department of Fusion Chemical Engineering, Hanyang University, Ansan 426-791 (Korea, Republic of); Lee, Young-In [Institute of Nanosensor Technology, Hanyang University, Ansan 426-791 (Korea, Republic of); Kim, Bum-Sung [Production Technology R and D Division, Korea Institute of Industrial Technology, Incheon 406-840 (Korea, Republic of); Choa, Yong-Ho, E-mail: choa15@hanyang.ac.kr [Department of Fusion Chemical Engineering, Hanyang University, Ansan 426-791 (Korea, Republic of); Institute of Nanosensor Technology, Hanyang University, Ansan 426-791 (Korea, Republic of)

2013-11-01

The compound Cu(In{sub 1−x}Ga{sub x})S{sub 2} (CIGS) was synthesized using copper oxide, indium oxide and gallium oxide mixture (CIGO) nanoparticles using salt-assisted ultrasonic spray pyrolysis (SAUSP). Under this method, CIGS can be produced without the complicated restrictions of a vacuum and an inert atmosphere. The band gap of CIGS can be controlled by introducing the desired stoichiometric quantities of starting materials. In order to synthesize CIGO nanoparticles, various NaCl/precursor ratios were used to accomplish the SAUSP process and ultimately monodisperse CIGO nanoparticles with average particle size of 9 nm without hard agglomeration were obtained. Subsequently, the CIGO nanoparticles were sulfurized to form the CIGS in H{sub 2}S/Ar atmosphere at 500 °C. The CIGS obtained in the present study has the various band gap ranging from 1.67 to 2.34 eV depending on the Ga / (In + Ga) ratio, and those band gap correspond to the respective bulk materials. - Highlights: • CIGS is obtained using Cu, In and Ga oxide mixture (CIGO) nanoparticles. • Salt-assisted ultrasonic spray pyrolysis is used to synthesize CIGO nanoparticles. • Nine nanometers of monodisperse CIGO nanoparticles without hard agglomeration is obtained. • The band gap of CIGS can be controlled by introducing the desired ratio of precursor.

A rapid green strategy for the synthesis of Au "meatball"-like nanoparticles using green tea for SERS applications

Science.gov (United States)

Wu, Shichao; Zhou, Xi; Yang, Xiangrui; Hou, Zhenqing; Shi, Yanfeng; Zhong, Lubin; Jiang, Qian; Zhang, Qiqing

2014-09-01

We report a simple and rapid biological approach to synthesize water-soluble and highly roughened "meatball"-like Au nanoparticles using green tea extract under microwave irradiation. The synthesized Au meatball-like nanoparticles possess excellent monodispersity and uniform size (250 nm in diameter). Raman measurements show that these tea-generated meatball-like gold nanostructures with high active surface areas exhibit a high enhancement of surface-enhanced Raman scattering. In addition, the Au meatball-like nanoparticles demonstrate good biocompatibility and remarkable in vitro stability at the biological temperature. Meanwhile, the factors that influence the Au meatball-like nanoparticles morphology are investigated, and the mechanisms behind the nonspherical shape evolution are discussed.

Fabrication of polystyrene porous films with gradient pore structures

International Nuclear Information System (INIS)

Yan Hongwei; Zhang Lin; Li Bo; Yin Qiang

2010-01-01

Silica opals and multilayer heterostructures were fabricated by vertical deposition technique. Polystyrene inverse opals and gradient porous structures were obtained by colloidal templating, in order to control the pore microstructure of polymer porous materials. As shown in the scanning electron microscopy images, the polystyrene porous structures are precise replicas of inverse structures of the original templates. After being infiltrated with the polystyrene, the photonic stop-band position of the opal composite is redshifted compared with the original template, and it is blueshifted after the opal template being removed. The filling ratio of polystyrene was calculated according to the Bragg formula. (authors)

Synthesis of high intrinsic loss power aqueous ferrofluids of iron oxide nanoparticles by citric acid-assisted hydrothermal-reduction route

International Nuclear Information System (INIS)

Behdadfar, Behshid; Kermanpur, Ahmad; Sadeghi-Aliabadi, Hojjat; Morales, Maria del Puerto; Mozaffari, Morteza

2012-01-01

Monodispersed aqueous ferrofluids of iron oxide nanoparticle were synthesized by hydrothermal-reduction route. They were characterized by X-ray diffraction analysis, Fourier transform infrared spectroscopy, scanning and transmission electron microscopy and dynamic light scattering. The results showed that certain concentrations of citric acid (CA) are required to obtain only magnetic iron oxides with mean particle sizes around 8 nm. CA acts as a modulator and reducing agent in iron oxide formation which controls nanoparticle size. The XRD, magnetic and heating measurements showed that the temperature and time of hydrothermal reaction can affect the magnetic properties of obtained ferrofluids. The synthesized ferrofluids were stable at pH 7. Their mean hydrodynamic size was around 80 nm with polydispersity index (PDI) of 0.158. The calculated intrinsic loss power (ILP) was 9.4 nHm 2 /kg. So this clean and cheap route is an efficient way to synthesize high ILP aqueous ferrofluids applicable in magnetic hyperthermia. - Graphical abstract: Monodispersed aqueous ferrofluids of iron oxide nanoparticles were synthesized by hydrothermal-reduction method with citric acid as reductant which is an efficient way to synthesize aqueous ferrofluids applicable in magnetic hyperthermia. Highlights: ► Aqueous iron oxide ferrofluids were synthesized by hydrothermal-reduction route. ► Citric acid acted as reducing agent and surfactant in the route. ► This is a facile, low energy and environmental friendly route. ► The aqueous iron oxide ferrofluids were monodispersed and stable at pH of 7. ► The calculated intrinsic loss power of the synthesized ferrofluids was very high.

Ordered CdSe nanoparticles within self-assembled block copolymer domains on surfaces.

Science.gov (United States)

Zou, Shan; Hong, Rui; Emrick, Todd; Walker, Gilbert C

2007-02-13

Hierarchical, high-density, ordered patterns were fabricated on Si substrates by self-assembly of CdSe nanoparticles within approximately 20-nm-thick diblock copolymer films in a controlled manner. Surface-modified CdSe nanoparticles formed well-defined structures within microphase-separated polystyrene-b-poly(2-vinylpyridine) (PS-b-P2VP) domains. Trioctylphosphine oxide (TOPO)-coated CdSe nanoparticles were incorporated into PS domains and polyethylene glycol-coated CdSe nanoparticles were located primarily in the P2VP domains. Nearly close-packed CdSe nanoparticles were clearly identified within the highly ordered patterns on Si substrates by scanning electron microscopy (SEM). Contact angle measurements together with SEM results indicate that TOPO-CdSe nanoparticles were partially placed at the air/copolymer interface.

The preparation of highly active antimicrobial silver nanoparticles by an organometallic approach

Energy Technology Data Exchange (ETDEWEB)

Fernandez, Eduardo J; Garcia-Barrasa, Jorge; Lopez-de-Luzuriaga, Jose M; Monge, Miguel [Departamento de Quimica Grupo de SIntesis Quimica de La Rioja, UA-CSIC, Universidad de La Rioja, Complejo CientIfico-Tecnologico, E-26004 Logrono (Spain); Laguna, Antonio [Departamento de Quimica Inorganica, Instituto de Ciencia de Materiales de Aragon, Universidad de Zaragoza-CSIC, E-50009 Zaragoza (Spain); Torres, Carmen [Departamento de Agricultura y Alimentacion, Universidad de La Rioja, Complejo Cientifico-Tecnologico, E-26004 Logrono (Spain)], E-mail: eduardo.fernandez@unirioja.es

2008-05-07

Silver nanoparticles of small size with a high surface to volume ratio have been prepared using an organometallic approach. For this, the complex NBu{sub 4}[Ag(C{sub 6}F{sub 5}){sub 2}] has been treated with AgClO{sub 4} in a 1:1 molar ratio, giving rise to the nanoparticle precursor [Ag(C{sub 6}F{sub 5})] in solution. Addition of one equivalent of hexadecylamine (HDA) and 5 h of reflux in toluene leads to a deep yellow solution containing monodisperse silver nanoparticles (Ag NPs) of ca. 10 nm. This approach leads to nanoparticles with almost uncontaminated surfaces which make them very reactive. Antimicrobial studies show that these nanoparticles are very active as antimicrobial agents. Very low concentrations between 12 and 25 {mu}g ml{sup -1} of Ag NPs are enough to produce bacteriostatic and bactericidal effectiveness.

Protein coated gold nanoparticles as template for the directed synthesis of highly fluorescent gold nanoclusters

Science.gov (United States)

Zhang, Lingyan; Han, Fei

2018-04-01

Bovine serum albumin (BSA) modified gold nanoparticles (AuNPs) was selected as template for the synthesis of AuNPs@gold nanoclusters (AuNCs) core/shell nanoparticles, in which BSA not only acted as dual functions agent for both anchoring and reducing Au3+ ions, but also was employed as a bridge between the AuNPs and AuNCs. Optical properties of AuNPs@AuNCs core/shell nanoparticles were studied using UV-visible and fluorescence spectroscopy. The prepared AuNPs@AuNCs core/shell nanoparticles exhibited sphere size uniformity with improved monodispersity, excellent fluorescence and fluorescent stability. Compared with AuNCs, AuNPs@AuNCs core/shell nanoparticles possessed large size and strong fluorescence intensity due to the effect of AuNPs as core. Moreover, the mechanism of the AuNPs induced fluorescence changes of the core/shell nanoparticles was first explored.

Silver nanoparticles: Large scale solvothermal synthesis and optical properties

Energy Technology Data Exchange (ETDEWEB)

Wani, Irshad A.; Khatoon, Sarvari [Nanochemistry Laboratory, Department of Chemistry, Jamia Millia Islamia, New Delhi 110025 (India); Ganguly, Aparna [Nanochemistry Laboratory, Department of Chemistry, Jamia Millia Islamia, New Delhi 110025 (India); Department of Chemistry, Indian Institute of Technology, Hauz Khas, New Delhi 110016 (India); Ahmed, Jahangeer; Ganguli, Ashok K. [Department of Chemistry, Indian Institute of Technology, Hauz Khas, New Delhi 110016 (India); Ahmad, Tokeer, E-mail: tokeer.ch@jmi.ac.in [Nanochemistry Laboratory, Department of Chemistry, Jamia Millia Islamia, New Delhi 110025 (India)

2010-08-15

Silver nanoparticles have been successfully synthesized by a simple and modified solvothermal method at large scale using ethanol as the refluxing solvent and NaBH{sub 4} as reducing agent. The nanopowder was investigated by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), dynamic light scattering (DLS), UV-visible and BET surface area studies. XRD studies reveal the monophasic nature of these highly crystalline silver nanoparticles. Transmission electron microscopic studies show the monodisperse and highly uniform nanoparticles of silver of the particle size of 5 nm, however, the size is found to be 7 nm using dynamic light scattering which is in good agreement with the TEM and X-ray line broadening studies. The surface area was found to be 34.5 m{sup 2}/g. UV-visible studies show the absorption band at {approx}425 nm due to surface plasmon resonance. The percentage yield of silver nanoparticles was found to be as high as 98.5%.

Rapid synthesis of gold and silver nanoparticles using tryptone as a reducing and capping agent

Science.gov (United States)

Mehta, Sourabh M.; Sequeira, Marilyn P.; Muthurajana, Harries; D'Souza, Jacinta S.

2018-02-01

Due to its eco-friendliness, recent times have seen an immense interest in the green synthesis of metallic nanoparticles. We present here, a protocol for the rapid and cheap synthesis of Au and Ag nanoparticles (NPs) using 1 mg/ml tryptone (trypsinized casein) as a reducing and capping agent. These nanoparticles are spherical, 10 nm in diameter and relatively monodispersed. The atoms of these NPs are arranged in face-centered cubic fashion. Further, when tested for their cytotoxic property against HeLa and VERO cell lines, gold nanoparticles were more lethal than silver nanoparticles, with a more or less similar trend observed against both Gram-positive and Gram-negative bacteria. On the other hand, the NPs were least cytotoxic against a unicellular alga, Chlamydomonas reinhardtii implying their eco-friendly property.

Review and outlook: from single nanoparticles to self-assembled monolayers and granular GMR sensors

Directory of Open Access Journals (Sweden)

Alexander Weddemann

2010-11-01

Full Text Available This paper highlights recent advances in synthesis, self-assembly and sensing applications of monodisperse magnetic Co and Co-alloyed nanoparticles. A brief introduction to solution phase synthesis techniques as well as the magnetic properties and aspects of the self-assembly process of nanoparticles will be given with the emphasis placed on selected applications, before recent developments of particles in sensor devices are outlined. Here, the paper focuses on the fabrication of granular magnetoresistive sensors by the employment of particles themselves as sensing layers. The role of interparticle interactions is discussed.

Different endocytotic uptake mechanisms for nanoparticles in epithelial cells and macrophages

Directory of Open Access Journals (Sweden)

Dagmar A. Kuhn

2014-09-01

Full Text Available Precise knowledge regarding cellular uptake of nanoparticles is of great importance for future biomedical applications. Four different endocytotic uptake mechanisms, that is, phagocytosis, macropinocytosis, clathrin- and caveolin-mediated endocytosis, were investigated using a mouse macrophage (J774A.1 and a human alveolar epithelial type II cell line (A549. In order to deduce the involved pathway in nanoparticle uptake, selected inhibitors specific for one of the endocytotic pathways were optimized regarding concentration and incubation time in combination with fluorescently tagged marker proteins. Qualitative immunolocalization showed that J774A.1 cells highly expressed the lipid raft-related protein flotillin-1 and clathrin heavy chain, however, no caveolin-1. A549 cells expressed clathrin heavy chain and caveolin-1, but no flotillin-1 uptake-related proteins. Our data revealed an impeded uptake of 40 nm polystyrene nanoparticles by J774A.1 macrophages when actin polymerization and clathrin-coated pit formation was blocked. From this result, it is suggested that macropinocytosis and phagocytosis, as well as clathrin-mediated endocytosis, play a crucial role. The uptake of 40 nm nanoparticles in alveolar epithelial A549 cells was inhibited after depletion of cholesterol in the plasma membrane (preventing caveolin-mediated endocytosis and inhibition of clathrin-coated vesicles (preventing clathrin-mediated endocytosis. Our data showed that a combination of several distinguishable endocytotic uptake mechanisms are involved in the uptake of 40 nm polystyrene nanoparticles in both the macrophage and epithelial cell line.

Immobilizing LaFeO{sub 3} nanoparticles on carbon spheres for enhanced heterogeneous photo-Fenton like performance

Energy Technology Data Exchange (ETDEWEB)

Wang, Kaixuan [School of Chemistry and Chemical Engineering, Anhui University, Hefei 230601 (China); Niu, Helin, E-mail: niuhelin@ahu.edu.cn [School of Chemistry and Chemical Engineering, Anhui University, Hefei 230601 (China); Chen, Jingshuai; Song, Jiming; Mao, Changjie; Zhang, Shengyi [School of Chemistry and Chemical Engineering, Anhui University, Hefei 230601 (China); Gao, Yuanhao [Institute of Surface Micro and Nano Materials, Xuchang University, Henan 461000 (China)

2017-05-15

Highlights: • LaFeO{sub 3} nanoparticles sub–10 nm were successfully immobilized on monodisperse carbon spheres for the first time through a facile and environmental friendly ultrasonic assisted surface ions adsorption method. • LaFeO{sub 3}/C nanocomposite exhibits much higher photo-Fenton like catalytic activity than LaFeO{sub 3}. • The superior property was attributed to the synergistic effects from the photo-Fenton like process and the presence of monodisperse carbon spheres. - Abstract: LaFeO{sub 3} nanoparticles immobilized on the surface of monodisperse carbon spheres have been obtained through a facile and environmentally friendly ultrasonic assisted surface ions adsorption method. The LaFeO{sub 3}/C nanocomposite was evaluated as photo-Fenton like catalyst for the degradation of Rhodamine B (RhB) under visible light irradiation (λ > 420 nm). The LaFeO{sub 3}/C nanocomposite possesses high specific surface area compared with pure LaFeO{sub 3} and significantly enhanced photo-Fenton like catalytic performance. The possible formation process of the LaFeO{sub 3}/C nanocomposite and the mechanism for photo-Fenton like reaction were discussed. The superior property was attributed to the synergistic effects from the photo-Fenton like process and the presence of carbon spheres. In addition, the heterogeneous process led to better recyclability of this type of catalyst.

Optimal sample preparation for nanoparticle metrology (statistical size measurements) using atomic force microscopy

International Nuclear Information System (INIS)

Hoo, Christopher M.; Doan, Trang; Starostin, Natasha; West, Paul E.; Mecartney, Martha L.

2010-01-01

Optimal deposition procedures are determined for nanoparticle size characterization by atomic force microscopy (AFM). Accurate nanoparticle size distribution analysis with AFM requires non-agglomerated nanoparticles on a flat substrate. The deposition of polystyrene (100 nm), silica (300 and 100 nm), gold (100 nm), and CdSe quantum dot (2-5 nm) nanoparticles by spin coating was optimized for size distribution measurements by AFM. Factors influencing deposition include spin speed, concentration, solvent, and pH. A comparison using spin coating, static evaporation, and a new fluid cell deposition method for depositing nanoparticles is also made. The fluid cell allows for a more uniform and higher density deposition of nanoparticles on a substrate at laminar flow rates, making nanoparticle size analysis via AFM more efficient and also offers the potential for nanoparticle analysis in liquid environments.

Damping of Mechanical Waves with Styrene/Butadiene Rubber Filled with Polystyrene Particle: Effects of Particles Size and Wave Frequency

Directory of Open Access Journals (Sweden)

M. Haghgo

2007-08-01

Full Text Available Utilizing polymeric materials for damping mechanical waves is of great importance in various fields of applications such as military camouflage, prevention of structural vibrational energy transfer, and noise attenuation. This ability originates from segmental dynamics of chain-like polymer molecules. Damping properties of styrene-butadiene rubbercontaining 10 wt% of monosize polystyrene particles with different diameters (from 80 nm to 500 μm was investigated in the frequency range of vibration, sound, and ultrasound via dynamic mechanical thermal analysis, normalsound adsorption test, and ultrasound attenuation coefficient measurement. The obtained results indicated that for different systems, containing different sizes of polystyrene particles, the area under the damping curve does not show significant change comparing to the neat SBR in the frequency range studied. However, addition of polystyrene particles, specifically nanosized particles, resulted in emergence of a secondary glass transition temperature which could be attributed to the modified dynamics of a layer of matrix molecules near the surface of PS particles. In the range of sound frequency, 0.5 to 6.3 kHz, the maximum damping was observed for the system containing polystyrene nanoparticles. However the single damping curve of neat SBR was separated into two or even three distinct curves owing to the presence of the particles. The maximum damping in the ultrasound frequency range was found for the system containing 0.5 mm polystyrene particles. This is attributed to different contributions from matrix chains dynamics and the reflection of mechanical waves from particles-matrix interface at different frequency ranges. On other words, the increase in the glass transition temperature of the elastomeric matrix phase with increasing the mechanical wave frequency causes a reduction in the contribution from matrix chains dynamics while the contribution due to diffraction from dispersed

The use of ultrasmall iron(0) nanoparticles as catalysts for the selective hydrogenation of unsaturated C-C bonds.

Science.gov (United States)

Kelsen, Vinciane; Wendt, Bianca; Werkmeister, Svenja; Junge, Kathrin; Beller, Matthias; Chaudret, Bruno

2013-04-28

The performance of well-defined ultrasmall iron(0) nanoparticles (NPs) as catalysts for the selective hydrogenation of unsaturated C-C and C=X bonds is reported. Monodisperse iron nanoparticles of about 2 nm size are synthesized by the decomposition of {Fe(N[Si(CH3)3]2)2}2 under dihydrogen. They are found to be active for the hydrogenation of various alkenes and alkynes under mild conditions and weakly active for C=O bond hydrogenation.

Influence of recycled polystyrene beads on cement paste properties

Directory of Open Access Journals (Sweden)

Maaroufi Maroua

2018-01-01

Full Text Available In order to keep up with the requirements of sustainable development, there is a growing interest towards reducing the energy consumption in the construction and rehabilitation of buildings and the promotion of recycling waste in building materials. The use of recycled polystyrene beads in cement-based materials composition constitutes a solution to improve the insulation in buildings. This allows also limiting landfill by reusing the polystyrene waste. The aim of this study is to compare some properties and performances of a cement paste containing polystyrene beads to a reference paste designed with only the same cement. An experimental campaign was conducted and the obtained results showed that adding recycled polystyrene beads to a cement paste improves its hygro-thermal properties. Further studies are however necessary to better understand the real role of the polystyrene beads in the heat and mass transfers.

Monodisperse selenium-substituted hydroxyapatite: Controllable synthesis and biocompatibility

Energy Technology Data Exchange (ETDEWEB)

Sun, Jianpeng [School of Civil Engineering, Xi' an University of Architecture and Technology, Shaanxi 710055 (China); Shaanxi Key Laboratory of Degradable Biomedical Materials, Shaanxi R& D Center of Biomaterials and Fermentation Engineering, School of Chemical and Engineering, Northwest University, Xi' an, 710069 (China); Zheng, Xiaoyan; Li, Hui; Fan, Daidi [Shaanxi Key Laboratory of Degradable Biomedical Materials, Shaanxi R& D Center of Biomaterials and Fermentation Engineering, School of Chemical and Engineering, Northwest University, Xi' an, 710069 (China); Song, Zhanping [School of Civil Engineering, Xi' an University of Architecture and Technology, Shaanxi 710055 (China); Ma, Haixia [Shaanxi Key Laboratory of Degradable Biomedical Materials, Shaanxi R& D Center of Biomaterials and Fermentation Engineering, School of Chemical and Engineering, Northwest University, Xi' an, 710069 (China); Hua, Xiufu, E-mail: hua_xiufu@163.com [Department of Scientific Research and Development, Tsinghua University, Beijing 100084 (China); Hui, Junfeng, E-mail: huijunfeng@126.com [Shaanxi Key Laboratory of Degradable Biomedical Materials, Shaanxi R& D Center of Biomaterials and Fermentation Engineering, School of Chemical and Engineering, Northwest University, Xi' an, 710069 (China)

2017-04-01

Hydroxyapatite (HA) is the major inorganic component of natural bone tissue. As an essential trace element, selenium involves in antioxidation and anticancer of human body. So far, ion-doped hydroxyapatites (HAs) are widely investigated owing to their great applications in field of biomaterial, biological labeling. In this paper, series of monodisperse HA doped with SeO{sub 3}{sup 2−} (SeHA) was successfully synthesized based on the liquid–solid–solution (LSS) strategy. The obtained samples were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) and energy-dispersive spectrometer (EDS). The results indicated that the SeO{sub 3}{sup 2−} doping level of the Se/(P + Se) molar ratio of 0– 0.4 can be requisitely controlled, and the morphology of SeHA nanoparticles varied from nanorods to nanoneedles with increasing Se/(P + Se) molar ratio. Significantly, the as-synthesized SeHA nanocrystals exhibit a low cytotoxicity for osteoblastic cells, showing exciting potentials for application in artificial scaffold materials inhibiting of tumor growth in bone. - Highlights: • Series of SeO{sub 3}{sup 2−} doped HA nanorods or/and nanoneedles were successfully synthesized. • The morphology of the HA nanocrystals can be easily controlled by changing the Se/(P + Se) molar ratio. • The as-synthesized SeHA nanocrystals exhibit a low cytotoxicity for osteoblastic cells. • Showing exciting potentials for application in artificial scaffold materials inhibiting of tumor growth in bone.

Monodisperse selenium-substituted hydroxyapatite: Controllable synthesis and biocompatibility

International Nuclear Information System (INIS)

Sun, Jianpeng; Zheng, Xiaoyan; Li, Hui; Fan, Daidi; Song, Zhanping; Ma, Haixia; Hua, Xiufu; Hui, Junfeng

2017-01-01

Hydroxyapatite (HA) is the major inorganic component of natural bone tissue. As an essential trace element, selenium involves in antioxidation and anticancer of human body. So far, ion-doped hydroxyapatites (HAs) are widely investigated owing to their great applications in field of biomaterial, biological labeling. In this paper, series of monodisperse HA doped with SeO 3 2− (SeHA) was successfully synthesized based on the liquid–solid–solution (LSS) strategy. The obtained samples were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) and energy-dispersive spectrometer (EDS). The results indicated that the SeO 3 2− doping level of the Se/(P + Se) molar ratio of 0– 0.4 can be requisitely controlled, and the morphology of SeHA nanoparticles varied from nanorods to nanoneedles with increasing Se/(P + Se) molar ratio. Significantly, the as-synthesized SeHA nanocrystals exhibit a low cytotoxicity for osteoblastic cells, showing exciting potentials for application in artificial scaffold materials inhibiting of tumor growth in bone. - Highlights: • Series of SeO 3 2− doped HA nanorods or/and nanoneedles were successfully synthesized. • The morphology of the HA nanocrystals can be easily controlled by changing the Se/(P + Se) molar ratio. • The as-synthesized SeHA nanocrystals exhibit a low cytotoxicity for osteoblastic cells. • Showing exciting potentials for application in artificial scaffold materials inhibiting of tumor growth in bone

Silica artificial opal incorporated with silver nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Li Wenjiang, E-mail: wjli@zju.edu.cn [Center for Optical and Electromagnetic Research, State Key Laboratory for Modern Optical Instrumentation, Zhejiang University, Joint Research Center of Photonics of the Royal Institute of Technology and Zhejiang University, Zijingang Campus, Room 210, East Building 5, Hangzhou 310058 (China); Sun Tan [Center for Optical and Electromagnetic Research, State Key Laboratory for Modern Optical Instrumentation, Zhejiang University, Joint Research Center of Photonics of the Royal Institute of Technology and Zhejiang University, Zijingang Campus, Room 210, East Building 5, Hangzhou 310058 (China)

2009-07-15

The silica artificial opal with a three-dimensional (3D) periodic structure was prepared using highly monodispersed silica microspheres by a force packing method in ITO glass cell. The silica artificial opal incorporated with silver nanoparticles was fabricated by the electroplating technique. The optical microscope images of the synthetic sample and the corresponding optical properties were measured after each treatment of electroplating-washing-drying circle. The transmission and reflection spectra presented a red shift, showing that the effective refractive index of the complex silver/silica opal increased after each electroplating. Combining the SEM images, it was seen that the silver nanoparticles could be directly deposited on the surface of silica spheres in the opaline structure. The silver/silica complex opal film could provide a simple way to tune the opal properties by controlling silver nanoparticles in the silica opal. The silver/silica opal crystal structures could be used for nano-photonic circuits, white-light LEDs or as photocatalysts.

Silica artificial opal incorporated with silver nanoparticles

International Nuclear Information System (INIS)

Li Wenjiang; Sun Tan

2009-01-01

The silica artificial opal with a three-dimensional (3D) periodic structure was prepared using highly monodispersed silica microspheres by a force packing method in ITO glass cell. The silica artificial opal incorporated with silver nanoparticles was fabricated by the electroplating technique. The optical microscope images of the synthetic sample and the corresponding optical properties were measured after each treatment of electroplating-washing-drying circle. The transmission and reflection spectra presented a red shift, showing that the effective refractive index of the complex silver/silica opal increased after each electroplating. Combining the SEM images, it was seen that the silver nanoparticles could be directly deposited on the surface of silica spheres in the opaline structure. The silver/silica complex opal film could provide a simple way to tune the opal properties by controlling silver nanoparticles in the silica opal. The silver/silica opal crystal structures could be used for nano-photonic circuits, white-light LEDs or as photocatalysts.

Synthesis and characterization of superparamagnetic nanoparticles obtained by precipitation in inverse microemulsion for biomedical applications

International Nuclear Information System (INIS)

Puca Pacheco, Mercedes; Guerrero Aquino, Marco; Tacuri Calanchi, Enrique; Lopez Campos, Raul G.

2013-01-01

In this work the preparation of nanoparticles of magnetite by methods of precipitation in inverse microemulsions and the conventional method 'Chemical Co-precipitation' is reported. Magnetite nanoparticles were characterized by X-ray diffraction, Moessbauer spectroscopy and vibrating sample magnetometer (VSM). The results showed that the nanoparticles obtained by the method of precipitation in inverse microemulsion showed a superparamagnetic behavior and had a particle average diameter of 9 nm, while by the conventional method 'Chemical Co-precipitation' were 17 nm. In addition, other benefits observed in the application of the method of precipitation in inverse microemulsion with regard to the conventional method is that it allowed obtaining spheroidal magnetite nanoparticles, monodisperse and with magnetic and chemical properties which might have better results in medical applications. (author)

Carboxylic acid effects on the size and catalytic activity of magnetite nanoparticles.

Science.gov (United States)

Hosseini-Monfared, Hassan; Parchegani, Fatemeh; Alavi, Sohaila

2015-01-01

Magnetite nanoparticles (Fe3O4-NPs) were successfully synthesized in diethylene glycol in the presence of carboxylic acids. They were characterized using XRD, SEM and FTIR. Carboxylic acid plays a critical role in determining the morphology, particle size and size distribution of the resulting particles. The results show that as-prepared magnetite nanoparticles are monodisperse and highly crystalline. The nanoparticles can be easily dispersed in aqueous media and other polar solvents due to coated by a layer of hydrophilic polyol and carboxylic acid ligands in situ. Easily prepared Fe3O4-NPs have been shown to be an active, recyclable, and highly selective catalyst for the epoxidation of cyclic olefins with aqueous 30% H2O2. Copyright © 2014 Elsevier Inc. All rights reserved.

Large scale solvothermal synthesis and a strategy to obtain stable Langmuir–Blodgett film of CoFe2O4 nanoparticles

International Nuclear Information System (INIS)

Thampi, Arya; Babu, Keerthi; Verma, Seema

2013-01-01

Highlights: • Large scale, monodisperse CoFe 2 O 4 nanoparticles by solvothermal route. • LB technique to obtain stable film of CoFe 2 O 4 nanoparticles over a large area. • Hydrophobicity of substrate was enhanced utilizing LB films of cadmium arachidate. • P–A isotherm and AFM cross sectional height profile analysis confirms stability. • Large scale organization of nanoparticles for surface pressure higher than 15 mN/m. -- Abstract: Nearly monodisperse oleic acid coated cobalt ferrite nanoparticles were synthesized in large scale by a simple solvothermal method utilizing N-methyl 2-Pyrrolidone (NMP) as a high boiling solvent. The magnetic oxide was further investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM) and vibrating sample magnetometer (VSM). Langmuir–Blodgett (LB) technique is discussed to obtain a 2D assembly of oleic acid coated CoFe 2 O 4 nanoparticles over a large area. We describe a method to obtain stable, condensed three layers of cadmium arachidate on a piranha treated glass substrate. The hydrophobic surface thus obtained was subsequently used for forming a stable monolayer of oleic acid stabilized cobalt ferrite nanoparticles at the air–water interface. The stability of the LB films at the air–water interface was studied by pressure–area isotherm curves and atomic force microscopy (AFM) cross sectional height profile analysis. 2D organization of the magnetic nanoparticles at different surface pressures was studied by TEM. Preparation of large area LB films of CoFe 2 O 4 nanoparticles is reported for a surface pressure more than 15 mN/m

Nanocomposite catalyst with palladium nanoparticles encapsulated in a polymeric acid: A model for tandem environmental catalysis

KAUST Repository

Isimjan, Tayirjan T.; He, Quan; Liu, Yong; Zhu, Jesse; Puddephatt, Richard J.; Anderson, Darren Jason

2013-01-01

The synthesis and characterization of a novel hybrid nanocomposite catalyst comprised of palladium nanoparticles embedded in polystyrene sulfonic acid (PSSH) and supported on metal oxides is reported. The catalysts are intended for application

Effect of planar extension on the structure and mechanical properties of polystyrene-poly(ethylene-¤co¤-butylene)-polystyrene triblock copolymers

DEFF Research Database (Denmark)

Daniel, C.; Hamley, I.W.; Mortensen, K.

2000-01-01

Two thermoplastic poly(styrene)-poly(ethylene-co-butylene) -poly(styrene) triblock copolymers containing either spherical or cylindrical poly(styrene) microdomains were pre-oriented through extensional flow. Small angle neutron scattering (SANS) measurements revealed that the pre-oriented triblock...

Synthesis in pilot plant scale and physical properties of sulfonated polystyrene

Directory of Open Access Journals (Sweden)

Martins Cristiane R.

2003-01-01

Full Text Available The homogenous sulfonation of polystyrene was developed in a pilot plant scale producing polymers with different sulfonation degrees (18 to 22 mole % of sulfonated styrene units. The reaction yield depends chiefly on the concentration ratio of acetyl sulfate and polystyrene. The morphological and thermal properties of the sulfonated polystyrene obtained by homogeneous sulfonation were studied by means of scanning electron microscopy, differential scanning calorimetry and thermogravimetry. The glass transition temperature of sulfonated polystyrene increases in relation to pure polystyrene and DCp was evaluated in order to confirm the strong interactions among the ~SO3H groups.

Dendrimer-Encapsulated Ruthenium Nanoparticles as Catalysts for Lithium-O2 Batteries

Energy Technology Data Exchange (ETDEWEB)

Bhattacharya, Priyanka; Nasybulin, Eduard N.; Engelhard, Mark H.; Kovarik, Libor; Bowden, Mark E.; Li, Shari; Gaspar, Daniel J.; Xu, Wu; Zhang, Jiguang

2014-12-01

Dendrimer-encapsulated ruthenium nanoparticles (DEN-Ru) have been used as catalysts in lithium-O2 batteries for the first time. Results obtained from UV-vis spectroscopy, electron microscopy and X-ray photoelectron spectroscopy show that the nanoparticles synthesized by the dendrimer template method are ruthenium oxide instead of metallic ruthenium reported earlier by other groups. The DEN-Ru significantly improve the cycling stability of lithium (Li)-O2 batteries with carbon black electrodes and decrease the charging potential even at low catalyst loading. The monodispersity, porosity and large number of surface functionalities of the dendrimer template prevent the aggregation of the ruthenium nanoparticles making their entire surface area available for catalysis. The potential of using DEN-Ru as stand-alone cathode materials for Li-O2 batteries is also explored.

Luminescence properties of Nd3+-doped Y2O3 nanoparticles in organic media

International Nuclear Information System (INIS)

Cui, Xiaoxia; Hou, Chaoqi; Lu, Jiabao; Gao, Chao; Wei, Wei; Peng, Bo

2011-01-01

Nd 3+ -doped yttrium oxide nanoparticles (Y 2 O 3 :Nd) with cubic phase were obtained successfully by a glycine-nitrate solution combustion method. The results of Fourier transform infrared spectra (FTIR) showed that the -OH groups residing on the nanoparticles surfaces were reduced effectively by modifying with capping agent. The modified Y 2 O 3 :Nd nanoparticles displayed good monodispersity and excellent luminescence in N,N-dimethylformamide (DMF) solvent. Some optical parameters were calculated by Judd-Ofelt analysis based on absorption and fluorescence spectra. A relative large stimulated emission cross section, 1.7 x 10 -20 cm 2 , of the 4 F 3/2 → 4 I 11/2 transition was calculated. Theses results show that the modified Y 2 O 3 :Nd nanoparticles display good luminescence behavior in organic media. (orig.)

ESR studies of the radiation effects on polystyrene

International Nuclear Information System (INIS)

Garrett, R.W.; O'Donnell, J.H.; Pomery, P.J.

1976-01-01

The aim of this work was to investigate the polystyrene system (both pure and commercial samples) to elucidate the type and percentage of each paramagnetic species upon exposure to various irradiation doses. The size of dose plays a vital role in the type of spectra obtained. Upon irradiation in vacuo, polystyrene displays ESR spectra which are basically triplet in character but the line spacing and intensities of components are observed to depend on the magnitude of the irradiation dose. G value for the total radicals present and for the individual species present as a function of dose have been obtained. The relative concentration of each paramagnetic species has been determined through computer simulation of the observed ESR spectra. The relative stability of the different species with respect to temperature is discussed. The results for deuterated polystyrene is used to support those obtained for the unsubstituted polystyrene system. (author)

Constancy in composition of polystyrene and polymethylmethacrylate plastics

International Nuclear Information System (INIS)

Schulz, R.J.; Nath, R.

1979-01-01

Variations in the atomic compostion, and mass and electron densities of polystyrene and polymethylmethacrylate (PMM) plastics were assessed from experimentally determined mass attenuation coefficients for 125 I and 137 Cs gamma rays. The means and standard deviations in the mass densities of 16 samples of PMM and 10 samples of polystyrene were found to be 1.174 +- 1.4% and 1.042 +- 0.6% g/cm 3 , respectively. Based upon transmission measurements on various solutions of ethyl alcohol in water, the standard deviations in the effective atomic numbers of PMM and polystyrene were determined to be 0.77% and 1.3%, respectively. Based upon experimentally determined mass attenuation coefficients for 137 Cs, the standard deviations in electron density for PMM and polystyrene were 0.5% and 1.2%, respectively. Similar measurements on tap water and two grades of distilled water failed to detect any differences in atomic composition

Synthesis and self-assembly of Chitosan-g-Polystyrene copolymer: A new route for the preparation of heavy metal nanoparticles

KAUST Repository

Francis, Raju S.; Baby, Deepa K.; Gnanou, Yves

2015-01-01

Amphiphilic graft copolymers made of a Chitosan (CS) backbone and three arm polystyrene (PS) grafts were prepared by "grafting onto" strategy using Toluene Diisocyanate. IR spectroscopy and SEC show the successful grafting process. SEM pictures

Encapsulation of hydrophobic dyes in polystyrene micro- and nanoparticles via swelling procedures.

Science.gov (United States)

Behnke, Thomas; Würth, Christian; Hoffmann, Katrin; Hübner, Martin; Panne, Ulrich; Resch-Genger, Ute

2011-05-01

Aiming at the derivation of a generalized procedure for the straightforward preparation of particles fluorescing in the visible and near-infrared (NIR) spectral region, different swelling procedures for the loading of the hydrophobic polarity-probe Nile Red into nano- and micrometer sized polystyrene particles were studied and compared with respect to the optical properties of the resulting particles. The effect of the amount of incorporated dye on the spectroscopic properties of the particles was investigated for differently sized beads with different surface chemistries, i.e., non-functionalized, amino-modified and PEG-grafted surfaces. Moreover, photostability and leaking studies were performed. The main criterion for the optimization of the dye loading procedures was a high and thermally and photochemically stable fluorescence output of the particles for the future application of these systems as fluorescent labels. © Springer Science+Business Media, LLC 2010

Green Synthesis of Robust, Biocompatible Silver Nanoparticles Using Garlic Extract

International Nuclear Information System (INIS)

White, G.V.; Kerscher, P.; Brown, R.M.; Morella, J.D.; Kitchens, C.L.; McAllister, W.; Dean, D.

2012-01-01

This paper details a facile approach for the synthesis of stable and monodisperse silver nanoparticles performed at ambient/low temperature, where Allium sativum (garlic) extract functions as the silver salt reducing agent during nanoparticle synthesis as well as the post synthesis stabilizing ligands. Varying the synthesis conditions provides control of particle size, size-distribution, and kinetics of particle formation. Infrared spectroscopy, energy dispersive X-ray chemical analysis, and high-performance liquid chromatography indicated that allicin and other carbohydrates in the garlic extract are the primary nanoparticle stabilizing moieties. The synthesized silver nanoparticles also demonstrate potential for biomedical applications, owing to (1) enhanced stability in biological media, (2) resistance to oxidation by the addition of H 2 O 2 , (3) ease and scalability of synthesis, and (4) lack of harsh chemicals required for synthesis. Cytotoxicity assays indicated no decrease in cellular proliferation for vascular smooth muscle cells and 3T3 fibroblasts at a concentration of 25 μg/mL, confirming that silver nanoparticles synthesized with garlic extract are potential candidates for future experimentation and implementation in the biomedical field.

Synthesis of Pt-immobilized on silica and polystyrene-encapsulated silica and their applications as electrocatalysts in the proton exchange membrane fuel cell

International Nuclear Information System (INIS)

Yi, Sung-Chul; Kim, Chang Young; Jung, Chi Young; Jeong, Sung Hoon; Kim, Wha Jung

2011-01-01

Nano sized Pt particles were successfully immobilized onto SiO 2 and polystyrene-encapsulated silica core shell (SiO 2 @PS). To make the immobilization of Pt onto both silica and polystyrene-encapsulated silica core shell, SiO 2 was first functionalized with -NH 2 using 3-amino propyl trimethoxysilane (APTMS) while for core shell, the negatively charged surface of polystyrene (PS) was changed with positive charge by cationic surfactant such as cetyltrimethylammonium chloride (CTACl) to make the formation of SiO 2 shell on preformed PS sphere. Transmission electron micrograph (TEM) images shows that Pt nanoparticles immobilized onto SiO 2 and SiO 2 @PS were to be 3-4 nm without agglomeraiton. The energy dispersive spectroscope (EDS) shows that Pt contents on both SiO 2 and SiO 2 @PS were to be 21.45% and 20.28%, respectively. In case of Pt-SiO 2 @PS, it is believed that Pt should have been immobilized onto PS surface and pore within SiO 2 shell as well as SiO 2 surface. The MEA fabricated with Pt-SiO 2 @PS shows better cell performance than of Pt-SiO 2 .

Facile synthesis of monodisperse superparamagnetic Fe{sub 3}O{sub 4}/PMMA composite nanospheres with high magnetization

Energy Technology Data Exchange (ETDEWEB)

Lan Fang; Liu Kexia; Jiang Wen; Zeng Xiaobo; Wu Yao; Gu Zhongwei, E-mail: Yaowu_amanda@126.com, E-mail: zwgu@scu.edu.cn [National Engineering Research Center for Biomaterials, Sichuan University, Chengdu 610064 (China)

2011-06-03

Monodisperse superparamagnetic Fe{sub 3}O{sub 4}/polymethyl methacrylate (PMMA) composite nanospheres with high saturation magnetization were successfully prepared by a facile novel miniemulsion polymerization method. The ferrofluid, MMA monomer and surfactants were co-sonicated and emulsified to form stable miniemulsion for polymerization. The samples were characterized by DLS, TEM, FTIR, XRD, TGA and VSM. The diameter of the Fe{sub 3}O{sub 4}/PMMA composite nanospheres by DLS was close to 90 nm with corresponding polydispersity index (PDI) as small as 0.099, which indicated that the nanospheres have excellent homogeneity in aqueous medium. The TEM results implied that the Fe{sub 3}O{sub 4}/PMMA composite nanospheres had a perfect core-shell structure with about 3 nm thin PMMA shells, and the core was composed of many homogeneous and closely packed Fe{sub 3}O{sub 4} nanoparticles. VSM and TGA showed that the Fe{sub 3}O{sub 4}/PMMA composite nanospheres with at least 65% high magnetite content were superparamagnetic, and the saturation magnetization was as high as around 39 emu g{sup -1} (total mass), which was only decreased by 17% compared with the initial bare Fe{sub 3}O{sub 4} nanoparticles.

Segmented block copolymers with monodisperse aramide end-segments

NARCIS (Netherlands)

Araichimani, A.; Gaymans, R.J.

2008-01-01

Segmented block copolymers were synthesized using monodisperse diaramide (TT) as hard segments and PTMO with a molecular weight of 2 900 g · mol-1 as soft segments. The aramide: PTMO segment ratio was increased from 1:1 to 2:1 thereby changing the structure from a high molecular weight multi-block

Assessment of morphology, topography and chemical composition of water-repellent films based on polystyrene/titanium dioxide nanocomposites

Energy Technology Data Exchange (ETDEWEB)

Bolvardi, Beleta [Chemical Engineering Department, Central Tehran Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Seyfi, Javad, E-mail: Jseyfi@gmail.com [Department of Chemical Engineering, Shahrood Branch, Islamic Azad University, P.O. Box 36155-163, Shahrood (Iran, Islamic Republic of); Hejazi, Iman, E-mail: Imanhe64@gmail.com [Applied Science Nano Research Group, ASNARKA, P.C. 1619948753, Tehran (Iran, Islamic Republic of); Otadi, Maryam [Chemical Engineering Department, Central Tehran Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Khonakdar, Hossein Ali [Department of Polymer Engineering, Faculty of Engineering, South Tehran Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Strasse 6, D-01069 Dresden (Germany); Drechsler, Astrid; Holzschuh, Matthias [Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Strasse 6, D-01069 Dresden (Germany)

2017-02-28

Highlights: • Self-cleaning behavior was attained for PS/TiO{sub 2} nanocomposite films. • A modified phase separation process resulted in a hierarchical morphology. • A proper level of uniformity in surface roughness is mandatory for superhydrophobicity. • The required amount of nanoparticles was highly reduced via the presented method. - Abstract: In this study, polystyrene (PS)/titanium dioxide (TiO{sub 2}) films were fabricated through simple solution casting technique via a modified phase separation process. The presented approach resulted in a remarkable reduction in the required amount of nanoparticles for achieving superhydrophobicity. Scanning electron microscopy (SEM) and 3D confocal microscopy were utilized to characterize surface morphology and topography of samples, respectively. An attempt was made to give an in-depth analysis on the surface rough structure using 3D roughness profiles. It was found that high inclusions of non-solvent and nanoparticles resulted in a stable self-cleaning behavior due to the strong presence of hydrophobic TiO{sub 2} nanoparticles on the surface. Quite unexpectedly, low inclusions of nanoparticles and non-solvent also resulted in superhydrophobic property mainly due to the proper level of induced surface roughness. XPS analysis was also utilized to determine the chemical composition of the films’ surfaces. The results of falling drop experiments showed that the sample containing a higher level of nanoparticles had a much lower mechanical resistance against the induced harsh conditions. All in all, the presented method has shown promising potential in fabrication of superhydrophobic surfaces with self-cleaning behavior using the lowest content of nanoparticles.

Effect of Ligand Molecular Weight and Nanoparticle Core Size on Polymer-Coated Gold Nanoparticle Location in Block Copolymers

Science.gov (United States)

Petrie, Joshua; Kim, Bumjoon; Fredrickson, Glenn; Kramer, Ed

2008-03-01

Gold nanoparticles modified by short chain polymer thiols [Au-PS] can be designed to strongly localize in either domain of a polystyrene-b-poly(2-vinylpyridine) [PS-PVP] block copolymer or at the interface. The P2VP block has a stronger attractive interaction with bare gold than the PS block. Thus, when the areal chain density σ of end-attached PS chains falls below a critical areal chain density σc the Au-PS nanoparticles adsorb to the PS-b-P2VP interface. The effect of the polymer ligand molecular weight on the σchas been shown to scale as σc˜ ((R+Rg)/(R*Rg))̂2, where R is the curvature of the Au nanoparticle core radius. To test this scaling relation for σc further we are synthesizing gold nanoparticles with different core radii and will present preliminary results on σcas a function of R.

Bidisperse silica nanoparticles close-packed monolayer on silicon substrate by three step spin method

Science.gov (United States)

Khanna, Sakshum; Marathey, Priyanka; Utsav, Chaliawala, Harsh; Mukhopadhyay, Indrajit

2018-05-01

We present the studies on the structural properties of monolayer Bidisperse silica (SiO2) nanoparticles (BDS) on Silicon (Si-100) substrate using spin coating technique. The Bidisperse silica nanoparticle was synthesised by the modified sol-gel process. Nanoparticles on the substrate are generally assembled in non-close/close-packed monolayer (CPM) form. The CPM form is obtained by depositing the colloidal suspension onto the silicon substrate using complex techniques. Here we report an effective method for forming a monolayer of bidisperse silica nanoparticle by three step spin coating technique. The samples were prepared by mixing the monodisperse solutions of different particles size 40 and 100 nm diameters. The bidisperse silica nanoparticles were self-assembled on the silicon substrate forming a close-packed monolayer film. The scanning electron microscope images of bidisperse films provided in-depth film structure of the film. The maximum surface coverage obtained was around 70-80%.

Lipase polystyrene giant amphiphiles.

Science.gov (United States)

Velonia, Kelly; Rowan, Alan E; Nolte, Roeland J M

2002-04-24

A new type of giant amphiphilic molecule has been synthesized by covalently connecting a lipase enzyme headgroup to a maleimide-functionalized polystyrene tail (40 repeat units). The resulting biohybrid forms catalytic micellar rods in water.

Biosynthesis, structural characterization and antimicrobial activity of gold and silver nanoparticles.

Science.gov (United States)

Ahmad, Tokeer; Wani, Irshad A; Manzoor, Nikhat; Ahmed, Jahangeer; Asiri, Abdullah M

2013-07-01

An eco friendly simple biosynthetic route was used for the preparation of monodisperse and highly crystalline gold and silver nanoparticles using cell free extract of fungus, Candida albicans. Transmission electron microscopic studies show the formation of gold and silver nanocrystals of average size of 5 nm and 30 nm with the specific surface areas of 18.9 m(2)/g and 184.4 m(2)/g respectively. The interaction of gold and silver nanoparticles with proteins has been formulated by FT-IR spectroscopy and thermal gravimetric analysis. The formation of gold and silver nanoparticles was also confirmed by the appearance of a surface plasmon band at 540 nm and 450 nm respectively. The antimicrobial activity of the synthesized gold and silver nanoparticles was investigated against both Staphylococcus aureus and Escherichia coli. The results suggest that these nanoparticles can be used as effective growth inhibitors against the test microorganisms. Greater bactericidal activity was observed for silver nanoparticles. The E. coli, a gram negative bacterium was found to be more susceptible to gold and silver nanoparticles than the S. aureus, a gram positive bacterium. Copyright © 2013 Elsevier B.V. All rights reserved.

Large scale solvothermal synthesis and a strategy to obtain stable Langmuir–Blodgett film of CoFe{sub 2}O{sub 4} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Thampi, Arya; Babu, Keerthi; Verma, Seema, E-mail: sa.verma@iiserpune.ac.in

2013-07-05

Highlights: • Large scale, monodisperse CoFe{sub 2}O{sub 4} nanoparticles by solvothermal route. • LB technique to obtain stable film of CoFe{sub 2}O{sub 4} nanoparticles over a large area. • Hydrophobicity of substrate was enhanced utilizing LB films of cadmium arachidate. • P–A isotherm and AFM cross sectional height profile analysis confirms stability. • Large scale organization of nanoparticles for surface pressure higher than 15 mN/m. -- Abstract: Nearly monodisperse oleic acid coated cobalt ferrite nanoparticles were synthesized in large scale by a simple solvothermal method utilizing N-methyl 2-Pyrrolidone (NMP) as a high boiling solvent. The magnetic oxide was further investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM) and vibrating sample magnetometer (VSM). Langmuir–Blodgett (LB) technique is discussed to obtain a 2D assembly of oleic acid coated CoFe{sub 2}O{sub 4} nanoparticles over a large area. We describe a method to obtain stable, condensed three layers of cadmium arachidate on a piranha treated glass substrate. The hydrophobic surface thus obtained was subsequently used for forming a stable monolayer of oleic acid stabilized cobalt ferrite nanoparticles at the air–water interface. The stability of the LB films at the air–water interface was studied by pressure–area isotherm curves and atomic force microscopy (AFM) cross sectional height profile analysis. 2D organization of the magnetic nanoparticles at different surface pressures was studied by TEM. Preparation of large area LB films of CoFe{sub 2}O{sub 4} nanoparticles is reported for a surface pressure more than 15 mN/m.

Controlling pore morphology and properties of nanoporous silica films using the different architecture PS-b-P2VP as a template.

Science.gov (United States)

Yu, Yang-Yen; Chien, Wen-Chen; Chen, Shih-Ting

2010-07-01

Nanoporous silica films were prepared through the templating of amphiphilic block copolymer, poly(styrene-2-vinyl pyridine) (PS-b-P2VP), and monodispersed colloidal silica nanoparticles. The experimental and theoretical studies suggested that the intermolecular hydrogen bonding existes between the colloidal silica nanoparticles and PS-b-P2VP. The effects of the loading ratio and P2VP chain length on the morphology and properties of the prepared nanoporous silica films were investigated. TEM and AFM studies showed that the uniform pore size could be achieved and the pore size increased with increasing porogen loading. The refractive index and dielectric constant of the prepared nanoporous films decreased with an increase in PS-b-P2VP loading. On the other hand, the porosity increased with an increasing PS-b-P2VP loading. This study demonstrated a methodology to control pore morphology and properties of the nanoporous silica films through the templating of PS-b-P2VP.

Green Synthesis, Characterization and Application of Proanthocyanidins-Functionalized Gold Nanoparticles

Directory of Open Access Journals (Sweden)

Linhai Biao

2018-01-01

Full Text Available Green synthesis of gold nanoparticles using plant extracts is one of the more promising approaches for obtaining environmentally friendly nanomaterials for biological applications and environmental remediation. In this study, proanthocyanidins-functionalized gold nanoparticles were synthesized via a hydrothermal method. The obtained gold nanoparticles were characterized by ultraviolet and visible spectrophotometry (UV-Vis, Fourier transform infrared spectroscopy (FTIR, transmission electron microscopy (TEM and X-ray diffraction (XRD measurements. UV-Vis and FTIR results indicated that the obtained products were mainly spherical in shape, and that the phenolic hydroxyl of proanthocyanidins had strong interactions with the gold surface. TEM and XRD determination revealed that the synthesized gold nanoparticles had a highly crystalline structure and good monodispersity. The application of proanthocyanidins-functionalized gold nanoparticles for the removal of dyes and heavy metal ions Ni2+, Cu2+, Cd2+ and Pb2+ in an aqueous solution was investigated. The primary results indicate that proanthocyanidins-functionalized gold nanoparticles had high removal rates for the heavy metal ions and dye, which implies that they have potential applications as a new kind of adsorbent for the removal of contaminants in aqueous solution.

Nanoparticle and nanosphere mask for etching of ITO nanostructures and their reflection properties

International Nuclear Information System (INIS)

Xu, Cigang; Deng, Ligang; Holder, Adam; Bailey, Louise R.; Proudfoot, Gary; Thomas, Owain; Gunn, Robert; Cooke, Mike; Leendertz, Caspar; Bergmann, Joachim

2015-01-01

Au nanoparticles and polystyrene nanospheres were used as mask for plasma etching of indium tin oxide (ITO) layer. By reactive ion etching (RIE) processes, the morphology of polystyrene nanospheres can be tuned through chemical or physical etching, and Au nanoparticle mask can result in ITO nanostructures with larger aspect ratio than nanosphere mask. During inductively coupled plasma (ICP) processes, Au nanoparticle mask was not affected by the thermal effect of plasma, whereas temperature of the substrate was essential to protect nanospheres from the damaging effect of plasma. Physical bombardment in the plasma can also modify the nanospheres. It was observed that under the same process conditions, the ratio of CH 4 and H 2 in the process gas can affect the etching rate of ITO without completely etching the nanospheres. The morphology of ITO nanostructures also depends on process conditions. The resulting ITO nanostructures show lower reflection in a spectral range of 400-1000 nm than c-Si and conventional antireflection layer of SiN x film. ITO nanostructures obtained after etching (scale bar = 200 nm). (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Green biosynthesis of silver nanoparticles using pomegranate peel and inhibitory effects of the nanoparticles on aflatoxin production

International Nuclear Information System (INIS)

Monira, A.O.; Mohammad, M.A.; Ashraf, H.A.

2017-01-01

In this work, pomegranate peel has been used as a natural and safe method for biosynthesis of silver nanoparticles. The synthesis of silver nanoparticles was confirmed using UV spectroscopy, which showed a peak around a wavelength of 437 nm. The morphology showed spherical and monodispersed nanoparticles with a size range between 5-50 nm. Using scanning electron microscopy (SEM) and transmission electron microscopy (TEM), X-ray diffraction (XRD) experiments revealed their crystalline nature. Active functional groups in the synthesized silver nanoparticles were determined using Fourier transform infrared (FTIR) spectrometers contained four bands at 3281.21 cm/sup -1/, possibly indicating the participationof O-H functional group. The peak take place at 1,636.22 cm/sup -1/ may be pointed to C = N bending in the amide group or C = O stretching in carboxyl. Transfer in this peak (from 1,641 to 1,643 cm/sup -1/) shown the possible role of amino groups or carboxyl in nanoparticle synthesis. The peaks at 431.95 and 421.28 cm/sup -1/ be related to AgNPs bonding with oxygen from hydroxyl groups which confirm the role of pomegranate peel as a reducing agent. Furthermore, we investigated effects of these nanoparticles on aflatoxin B1 production by the fungus Aspergillus flavus, isolated from hazelnut. The results found that aflatoxin production in all A. flavus isolates decreased with an increase in the concentration of silver nanoparticles. Maximum suppression of aflatoxin production was recorded at a nanoparticle concentration of 150 ppm. (author)

Decomposition kinetic and mechanism of syndiotactic polystyrene nanocomposites with MWCNTs and nanodiamonds studied by TGA and Py-GC/MS

Energy Technology Data Exchange (ETDEWEB)

Chrissafis, Konstantinos; Pavlidou, Eleni [Solid State Physics Section, Physics Department, Aristotle University of Thessaloniki, GR-541 24 Thessaloniki, Macedonia (Greece); Vouvoudi, Evangelia [Laboratory of Polymer Chemistry and Technology, Department of Chemistry, Aristotle University of Thessaloniki, GR-541 24 Thessaloniki, Macedonia (Greece); Bikiaris, Dimitrios, E-mail: dbic@chem.auth.gr [Laboratory of Polymer Chemistry and Technology, Department of Chemistry, Aristotle University of Thessaloniki, GR-541 24 Thessaloniki, Macedonia (Greece)

2014-05-01

Graphical abstract: - Highlights: • Syndiotactic polystyrene nanocomposites containing MWCNTs and nanodiamonds were prepared for first time. • Addition of nanofillers causes a substantial improvement of sPS thermal stability. • From EGA and Py-GC/MS, it was found that sPS decomposes through a radical process. • The decomposition mechanism of sPS was not affected by the addition of nanoparticles. - Abstract: In the present work, syndiotactic polystyrene (sPS) based nanocomposites containing 3 wt% of multi-walled carbon nanotubes (MWCNTs) and nanodiamonds (NDs) were prepared using the melt-mixing technique. Transmission electron microscopy (TEM) micrographs verified a good dispersion of the nanoparticles in the polymeric matrix, which resulted in a slight improvement of the mechanical properties of the nanocomposites. The addition of MWCNTs promotes the formation of β-type crystals while in sPS and sPS/NDs α-type crystals are mainly formed. From the thermogravimetric analysis experiments a substantial enhancement of sPS thermal stability was found, caused by the addition of nanofillers, especially from NDs. The temperature corresponding to a mass loss of 0.5% was found 295 °C for sPS, 352.4 °C for sPS-MWCNTs and 370.7 °C for sPS-NDs nanocomposites. The analytical method of Py-GC/MS was also used for further characterization of the samples. The main chain fragments collected from sPS pyrolysis were styrene monomers, dimers and trimers, while the three pyrolization temperatures applied (390, 420 and 500 °C) indicated some variations in intensity of decomposition fragments. The decomposition temperature as well as the nanoparticle addition (NDs or MWCNTs) affected the intensity of the recorded fragments but did not induce a change on the decomposition mechanism of sPS.

Core/Shell Structured Magnetic Nanoparticles for Biological Applications

International Nuclear Information System (INIS)

Park, Jeong Chan; Jung, Myung Hwan

2013-01-01

Magnetic nanoparticles have been widely used for biomedical applications, such as magnetic resonance imaging (MRI), hyperthermia, drug delivery and cell signaling. The surface modification of the nanomaterials is required for biomedical use to give physiogical stability, surface reactivity and targeting properties. Among many approaches for the surface modification with materials, such as polymers, organic ligands and metals, one of the most attractive ways is using metals. The fabrication of metal-based, monolayer-coated magnetic nanoparticles has been intensively studied. However, the synthesis of metal-capped magnetic nanoparticles with monodispersities and controllable sizes is still challenged. Recently, gold-capped magnetic nanoparticles have been reported to increase stability and to provide biocompatibility. Magnetic nanoparticle with gold coating is an attractive system, which can be stabilized in biological conditions and readily functionalized in biological conditions and readily functionalized through well-established surface modification (Au-S) chemistry. The Au coating offers plasmonic properties to magnetic nanoparticles. This makes the magnetic/Au core/shell combinations interesting for magnetic and optical applications. Herein, the synthesis and characterization of gold capped-magnetic core structured nanomaterials with different gold sources, such as gold acetate and chloroauric acid have been reported. The core/shell nanoparticles were transferred from organic to aqueous solutions for biomedical applications. Magnetic core/shell structured nanoparticles have been prepared and transferred from organic phase to aqueous solutions. The resulting Au-coated magnetic core nanoparticles might be an attractive system for biomedical applications, which are needed both magnetic resonance imaging and optical imaging

Synthesis of Polystyrene/MCM–41 Nanocomposites through AGET ATRP and ARGET ATRP

Directory of Open Access Journals (Sweden)

Khezrollah Khezri

2015-07-01

Full Text Available Polystyrene/MCM–41 nanocomposites were synthesized by atom transfer radical polymerization (ATRP at 110°C. Activators generated by electron transfer (AGET and activators regenerated by electron transfer (ARGET, as two novel initiation techniques, for ATRP were used. Specific structure, surface area, particles size and their distribution and spongy and porous structure of the synthesized MCM–41 nanoparticles were evaluated using X–ray diffraction, nitrogen adsorption/desorption isotherm analysis, scanning and transmission electron microscopy images, respectively. The final monomer conversion was determined using gas chromatography. Number and weight average molecular weights (Mn and Mw and polydispersity index (PDI were also evaluated by gel permeationchromatography. According to the results, addition of 3 wt% MCM–41 nanoparticles into the polymerization media resulted in lowering conversion from 81 to 58% in the AGET ATRP system. Moreover, a reduction in the molecular weight of the products from 17116 to 12798 g/mol was also occurred, although, the polydispersity index increased from 1.24 to 1.58. The similar results were also obtained by ARGET ATRP system; lowering conversion from 69 to 43% and molecular weight from 14892 to 9297 g/mol, and an increase of PDI from 1.14 to 1.41. The improvement in thermal stability of the nanocomposites, as a result of higher MCM–41 nanoparticles loading, was confirmed by thermogravimetric analysis. In addition, according to the analytical results of differential scanning calorimetry, a decrease in glass transition temperature, due to the addition of 3 wt% of MCM–41 nanoparticles (from 100.1 to 91.5°C in AGET ATRP system and from 100.3 to 85.8°C in ARGET ATRP, was achieved.

Nanocomposite Membrane via Magnetite Nanoparticle Assembly

KAUST Repository

Xie, Yihui

2012-07-01

Membrane technology is one of the most promising technologies for addressing the global water crisis as well as in many other applications. One of the drawbacks of current ultra- and nanofiltration membranes is the relatively broad pore size distribution. Block copolymer membranes with ultrahigh permeability and very regular pore sizes have been recently demonstrated with pores being formed by the supramolecular assembly of core/shell micelles. Our study aimed at developing an innovative and economically efficient alternative method to fabricate isoporous membrane by self-assembly of magnetic nanoparticle with a polystyrene shell, mimicking the behavior of block copolymer micelle. Fe3O4 nanoparticles of ~13 nm diameter were prepared by co-precipitation as cores. The initiator for ATRP was covalently bonded onto the surface of magnetic nanoparticles with two strategies. Then the surface initiated ATRP of styrene was carried out to functionalize nanoparticles with polystyrene through a “grafting from” method. Finally, the nanocomposite membrane was cast from 50 wt % Fe3O4@PS brush polymer solution in DMF via non solvent phase inversion. Microscopies reveal an asymmetric membrane with a dense thin layer on top of a porous sponge-like layer. This novel class of asymmetric membrane, based on the pure assembly of functionalized nanoparticles was prepared for the first time. The nanoparticles are well distributed however with no preferential order yet in the as-cast film.I would like to thank my committee chair and advisor, Prof. Suzana Nunes, and other committee members, Prof. Klaus-Viktor Peinemann and Prof. Gary Amy, for their guidance and support throughout the course of this research. My appreciation also goes to my colleagues in our group for useful discussions and suggestions. I also want to extend my gratitude to the staff from the KAUST Core Lab for Advanced Nanofabrication, Imaging and Characterization, especially Dr. Ali Reza Behzad, Dr. Rachid Sougrat, and

Modification of Jute Fibers with Polystyrene via Atom Transfer Radical Polymerization

DEFF Research Database (Denmark)

Plackett, David; Jankova, Katja Atanassova; Egsgaard, Helge

2005-01-01

Atom transfer radical polymerization (ATRP) was investigated as a method of covalently bonding polystyrene to jute (Corchorus capsularis) and as a possible approach to fiber composites with enhanced properties. Jute fibers were modified with a brominated initiator and subsequently ATRP modified...... to attach polystyrene and then examined using SEM, DSC, TGA, FTIR, XPS, elemental analysis, and Py-GC-MS. These techniques confirmed that polystyrene had been covalently bound to the fibers and consequently ATRP-modified jute fiber mats were used to prepare hot-pressed polystyrene composites. Composite...

Attomolar detection of proteins via cascade strand-displacement amplification and polystyrene nanoparticle enhancement in fluorescence polarization aptasensors.

Science.gov (United States)

Huang, Yong; Liu, Xiaoqian; Huang, Huakui; Qin, Jian; Zhang, Liangliang; Zhao, Shulin; Chen, Zhen-Feng; Liang, Hong

2015-08-18

Extremely sensitive and accurate measurements of protein markers for early detection and monitoring of diseases pose a formidable challenge. Herein, we develop a new type of amplified fluorescence polarization (FP) aptasensor based on allostery-triggered cascade strand-displacement amplification (CSDA) and polystyrene nanoparticle (PS NP) enhancement for ultrasensitive detection of proteins. The assay system consists of a fluorescent dye-labeled aptamer hairpin probe and a PS NP-modified DNA duplex (assistant DNA/trigger DNA duplex) probe with a single-stranded part and DNA polymerase. Two probes coexist stably in the absence of target, and the dye exhibits relatively low FP background. Upon recognition and binding with a target protein, the stem of the aptamer hairpin probe is opened, after which the opened hairpin probe hybridizes with the single-stranded part in the PS NP-modified DNA duplex probe and triggers the CSDA reaction through the polymerase-catalyzed recycling of both target protein and trigger DNA. Throughout this CSDA process, numerous massive dyes are assembled onto PS NPs, which results in a substantial FP increase that provides a readout signal for the amplified sensing process. Our newly proposed amplified FP aptasensor enables the quantitative measurement of proteins with the detection limit in attomolar range, which is about 6 orders of magnitude lower than that of traditional homogeneous aptasensors. Moreover, this sensing method also exhibits high specificity for target proteins and can be performed in homogeneous solutions. In addition, the suitability of this method for the quantification of target protein in biological samples has also been shown. Considering these distinct advantages, the proposed sensing method can be expected to provide an ultrasensitive platform for the analysis of various types of target molecules.

Magnetic Properties of Iron-Cobalt Oxide Nanocomposites Synthesized in Polystyrene Resin Matrix*

Science.gov (United States)

Vaishnava, P. P.; Senaratne, U.; Rodak, D.; Kroll, E.; Tsoi, G.; Naik, R.; Naik, V.; Wenger, L. E.; Tao, Qu; Boolchand, P.; Suryanarayanan, R.

2004-03-01

Magnetic nanoparticles have potential applications in memory devices and medical technology. Magnetic iron-cobalt oxide nanoparticles were prepared by in situ precipitation in an ion exchange resin using the method of Ziolo et al^1. The ion exchange resin, consisting of sulfonated divinyl benzene cross linked polystyrene, was exposed to different iron and cobalt salt solutions: a) 4FeCl2 + CoCl2 b) 9FeCl2 + CoCl2 c) 4FeCl3 + CoCl2 d) 9FeCl3 + CoCl_2. The ions bound to the resin are then oxidized with hydrogen peroxide in an alkaline media with mild heat. The resulting nanocomposites were characterized by X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), Fe^57 Mossbauer Spectroscopy and SQUID magnetometry. It was found that the oxide composition, particle size distribution, magnetic properties including blocking temperature and the amount of superparamagnetic phases are strongly influenced by the stoichiometry of the starting FeCl_2, FeCl_3, and CoCl2 solutions. Three major phases CoFe_2O_4, Fe_3O4 and γ-Fe_2O3 have been identified. The nanocomposites prepared using Fe^2+ and Co^2+ contain larger nanoparticles (10 nm) than those prepared by Fe^3+ and Co^2+ (3 nm) . The details of the structural characterization by XRD and TEM measurements and magnetic characteristics will be presented. *Research supported by NSF grant DGE 980720 ^1Ziolo et al, Science, 257, 5067 (1992).

Ultra-pure, water-dispersed Au nanoparticles produced by femtosecond laser ablation and fragmentation

Directory of Open Access Journals (Sweden)

Kubiliūtė R

2013-07-01

Full Text Available Reda Kubiliūtė,1,2 Ksenia A Maximova,3 Alireza Lajevardipour,1 Jiawey Yong,1 Jennifer S Hartley,1 Abu SM Mohsin,1 Pierre Blandin,3 James WM Chon,1 Marc Sentis,3 Paul R Stoddart,1 Andrei Kabashin,3 Ričardas Rotomskis,2 Andrew HA Clayton,1,4 Saulius Juodkazis1,4 1Centre for Micro-Photonics and Industrial Research Institute Swinburne, Faculty of Engineering and Industrial Sciences Swinburne University of Technology, Hawthorn, VIC, Australia; 2Laboratory of Biomedical Physics, Vilnius University Institute of Oncology, Baublio, Vilnius, Lithuania; 3Aix-Marseille University, Centre National de la Recherche Scientifique (CNRS, Lasers, Plasmas and Photonics Processing Laboratory, Campus de Luminy, Marseille, France; 4The Australian National Fabrication Facility, Victoria node, Faculty of Engineering and Industrial Sciences, Swinburne University of Technology, Hawthorn, VIC, Australia Abstract: Aqueous solutions of ultra-pure gold nanoparticles have been prepared by methods of femtosecond laser ablation from a solid target and fragmentation from already formed colloids. Despite the absence of protecting ligands, the solutions could be (1 fairly stable and poly size-dispersed; or (2 very stable and monodispersed, for the two fabrication modalities, respectively. Fluorescence quenching behavior and its intricacies were revealed by fluorescence lifetime imaging microscopy in rhodamine 6G water solution. We show that surface-enhanced Raman scattering of rhodamine 6G on gold nanoparticles can be detected with high fidelity down to micromolar concentrations using the nanoparticles. Application potential of pure gold nanoparticles with polydispersed and nearly monodispersed size distributions are discussed. Keywords: nanotechnologies applications, methods of nanofabrication and processing, materials for nanomedicine

Titanium Nitride Nanoparticle Electrocatalysts for Oxygen Reduction Reaction in Alkaline Solution

KAUST Repository

Ohnishi, R.

2013-03-12

Monodispersed TiN nanoparticles with a narrow size distribution (7–23 nm) were synthesized using mesoporous graphitic (mpg)-C3N4 templates with different pore sizes. The nano-materials were examined as electrocatalysts for oxygen reduction reaction (ORR) in alkaline media. The TiN nanoparticles were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N2 sorption, transmission electron microscopy (TEM), and C-H-N elemental analysis. The ORR current increased as the TiN particle size decreased, and hence the surface area of TiN nanoparticles reactive to ORR increased. Rotating ring disk electrode (RRDE) measurements revealed that the ORR on TiN surfaces proceeded mainly via a two-electron pathway, producing H2O2 as the main product. Mechanistic aspects of ORR on TiN surfaces are discussed.

Titanium Nitride Nanoparticle Electrocatalysts for Oxygen Reduction Reaction in Alkaline Solution

KAUST Repository

Ohnishi, R.; Katayama, M.; Cha, Dong Kyu; Takanabe, Kazuhiro; Kubota, J.; Domen, K.

2013-01-01

Monodispersed TiN nanoparticles with a narrow size distribution (7–23 nm) were synthesized using mesoporous graphitic (mpg)-C3N4 templates with different pore sizes. The nano-materials were examined as electrocatalysts for oxygen reduction reaction (ORR) in alkaline media. The TiN nanoparticles were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N2 sorption, transmission electron microscopy (TEM), and C-H-N elemental analysis. The ORR current increased as the TiN particle size decreased, and hence the surface area of TiN nanoparticles reactive to ORR increased. Rotating ring disk electrode (RRDE) measurements revealed that the ORR on TiN surfaces proceeded mainly via a two-electron pathway, producing H2O2 as the main product. Mechanistic aspects of ORR on TiN surfaces are discussed.

Comparative characteristics of polystyrene scintillation strips

International Nuclear Information System (INIS)

Gapienko, V.A.; Denisov, A.G.; Mel'nikov, E.A.

1992-01-01

Results are provided for a study of the main characteristics of polystyrene scintillation strips with a cross-section of 200 x 10 mm with two different scintillation-additive compositions: 1.5% p-terphenyl + 0.01% POPOP and 1.5% p-terphenyl + 0.01% DBP. The mean light-attenuation lengths are 180 cm and 260 cm, respectively, for strips with POPOP and DBP. The emittances of the polystyrene scintillators with DBP and POPOP additives have a ratio of 0.8:1.0 as recorded by an FEU-110 photomultiplier. 2 refs., 1 fig., 2 tabs

Monodisperse superparamagnetic nanoparticles by thermolysis of Fe(III) oleate and mandelate complexes

Czech Academy of Sciences Publication Activity Database

Patsula, Vitalii; Petrovský, Eduard; Kovářová, Jana; Konefal, Rafal; Horák, Daniel

2014-01-01

Roč. 292, č. 9 (2014), s. 2097-2110 ISSN 0303-402X R&D Projects: GA ČR GAP206/12/0381; GA MŠk 7E12053 EU Projects: European Commission(XE) 246513 - NADINE Institutional support: RVO:61389013 ; RVO:67985530 Keywords : superparamagnetic * nanoparticles * iron oxide Subject RIV: CD - Macromolecular Chemistry; DE - Earth Magnetism, Geodesy, Geography (GFU-E) Impact factor: 1.865, year: 2014

In vitro gastrointestinal digestion increases the translocation of polystyrene nanoparticles in an in vitro intestinal co-culture model.

Science.gov (United States)

Walczak, Agata P; Kramer, Evelien; Hendriksen, Peter J M; Helsdingen, Richard; van der Zande, Meike; Rietjens, Ivonne M C M; Bouwmeester, Hans

2015-01-01

The conditions of the gastrointestinal tract may change the physicochemical properties of nanoparticles (NPs) and therewith the bioavailability of orally taken NPs. Therefore, we assessed the impact of in vitro gastrointestinal digestion on the protein corona of polystyrene NPs (PS-NPs) and their subsequent translocation across an in vitro intestinal barrier. A co-culture of intestinal Caco-2 and HT29-MTX cells was exposed to 50 nm PS-NPs of different charges (positive and negative) in two forms: pristine and digested in an in vitro gastrointestinal digestion model. In vitro digestion significantly increased the translocation of all, except the "neutral", PS-NPs. Upon in vitro digestion, translocation was 4-fold higher for positively charged NPs and 80- and 1.7-fold higher for two types of negatively charged NPs. Digestion significantly reduced the amount of protein in the corona of three out of four types of NPs. This reduction of proteins was 4.8-fold for "neutral", 3.5-fold for positively charged and 1.8-fold for one type of negatively charged PS-NPs. In vitro digestion also affected the composition of the protein corona of PS-NPs by decreasing the presence of higher molecular weight proteins and shifting the protein content of the corona to low molecular weight proteins. These findings are the first to report that in vitro gastrointestinal digestion significantly affects the protein corona and significantly increases the in vitro translocation of differently charged PS-NPs. These findings stress the importance of including the in vitro digestion in future in vitro intestinal translocation screening studies for risk assessment of orally taken NPs.

Nanoparticles as image enhancing agents for ultrasonography

Energy Technology Data Exchange (ETDEWEB)

Liu Jun [Biomedical Engineering Department, Ohio State University, 270 Bevis Hall, 1080 Carmack Rd, Columbus, OH 43210 (United States); Levine, Andrea L [Department of Veterinary Biosciences, Ohio State University, 1925 Coffey Rd, Columbus, OH 43210 (United States); Mattoon, John S [Department of Veterinary Clinical Sciences, Ohio State University, 1151 Veterinary Hospital, 601 Vernon Tharp St., Columbus, OH 43210 (United States); Yamaguchi, Mamoru [Department of Veterinary Biosciences, Ohio State University, 1925 Coffey Rd, Columbus, OH 43210 (United States); Lee, Robert J [Division of Pharmaceutics, College of Pharmacy, NCI Comprehensive Cancer Center, and NSF Nanoscale Science and Engineering Center, Ohio State University, 500 West 12th Avenue, Columbus, OH 43210 (United States); Pan Xueliang [Department of Statistics, Ohio State University, 1958 Neil Avenue, Columbus, OH 43210 (United States); Rosol, Thomas J [Department of Veterinary Biosciences, Ohio State University, 1925 Coffey Rd, Columbus, OH 43210 (United States)

2006-05-07

Nanoparticles have drawn great attention as targeted imaging and/or therapeutic agents. The small size of the nanoparticles allows them to target cells that are beyond capillary vasculature, such as cancer cells. We investigated the effect of solid nanoparticles for enhancing ultrasonic grey scale images in tissue phantoms and mouse livers in vivo. Silica nanospheres (100 nm) were dispersed in agarose at 1-2.5% mass concentration and imaged by a high-resolution ultrasound imaging system (transducer centre frequency: 30 MHz). Polystyrene particles of different sizes (500-3000 nm) and concentrations (0.13-0.75% mass) were similarly dispersed in agarose and imaged. Mice were injected intravenously with nanoparticle suspensions in saline. B-mode images of the livers were acquired at different time points after particle injection. An automated computer program was used to quantify the grey scale changes. Ultrasonic reflections were observed from nanoparticle suspensions in agarose gels. The image brightness, i.e., mean grey scale level, increased with particle size and concentration. The mean grey scale of mouse livers also increased following particle administration. These results indicated that it is feasible to use solid nanoparticles as contrast enhancing agents for ultrasonic imagin000.

Electrospray methodologies for characterization and deposition of nanoparticles

Science.gov (United States)

Modesto Lopez, Luis Balam

Electrospray is an aerosolization method that generates highly charged droplets from solutions or suspensions and, after a series of solvent evaporation -- droplet fission cycles, it results in particles carrying multiple charges. Highly charged particles are used in a variety of applications, including particle characterization, thin film deposition, nanopatterning, and inhalation studies among several others. In this work, a soft X-ray photoionization was coupled with an electrospray to obtain monodisperse, singly charged nanoparticles for applications in online size characterization with electrical mobility analysis. Photoionization with the soft X-ray charger enhanced the diffusion neutralization rate of the highly charged bacteriophages, proteins, and solid particles. The effect of nanoparticle surface charge and nanoparticle agglomeration in liquids on the electrospray process was studied experimentally and a modified expression to calculate the effective electrical conductivity of nanosuspensions was proposed. The effective electrical conductivity of TiO2 nanoparticle suspensions is strongly dependent on the electrical double layer and the agglomeration dynamics of the particles; and such dependence is more remarkable in liquids with low ionic strength. TiO2 nanoparticle agglomerates with nearly monodisperse sizes in the nanometer and submicrometer ranges were generated, by electrospraying suspensions with tuned effective electrical conductivity, and used to deposit photocatalytic films for water-splitting. Nanostructured films of iron oxide with uniform distribution of particles over the entire deposition area were formed with an electrospray system. The micro-Raman spectra of the iron oxide films showed that transverse and longitudinal optical modes are highly sensitive to the crystallize size of the electrospray-deposited films. The fabrication of films of natural light-harvesting complexes, with the aim of designing biohybrid photovoltaic devices, was

Study on the interaction between gold nanoparticles and papain by spectroscopic methods

International Nuclear Information System (INIS)

Wang, Gongke; Chen, Ye; Yan, Changling; Lu, Yan

2015-01-01

The interaction between gold nanoparticles and papain was studied by fluorescence, UV–vis absorption and synchronous fluorescence spectroscopic techniques under the physiological conditions. The results showed that the binding of gold nanoparticles to papain was a spontaneous binding process. The fluorescence of papain was strongly quenched by gold nanoparticles. The quenching mechanism was probably a static quenching type with the formation of a ground state complex. The Stern–Volmer quenching constants, the binding constants and the number of binding sites in different temperatures were calculated. The corresponding thermodynamic parameters ΔH,ΔS and ΔG indicated that hydrogen bonding and Van der Waals forces played a key role in the interaction process. Additionally, the conformational change of papain induced by gold nanoparticles was analyzed by UV–vis absorption and synchronous fluorescence spectra. - Highlights: • Spherical and monodispersed gold nanoparticles are synthesized. • The fluorescence of papain is quenched by gold nanoparticles under physiological conditions. • Hydrogen bonding and Van der Waals forces may play an essential role in the binding of gold nanoparticles with papain. • This binding interaction is predominantly enthalpy driven

Amperometric glucose sensor based on enhanced catalytic reduction of oxygen using glucose oxidase adsorbed onto core-shell Fe3O4-silica-Au magnetic nanoparticles

International Nuclear Information System (INIS)

Wang Aijun; Li Yongfang; Li Zhonghua; Feng Jiuju; Sun Yanli; Chen Jianrong

2012-01-01

Monodisperse Fe 3 O 4 magnetic nanoparticles (NPs) were prepared under facile solvothermal conditions and successively functionalized with silica and Au to form core/shell Fe 3 O 4 -silica-Au NPs. Furthermore, the samples were used as matrix to construct a glucose sensor based on glucose oxidase (GOD). The immobilized GOD retained its bioactivity with high protein load of 3.92 × 10 −9 mol·cm −2 , and exhibited a surface-controlled quasi-reversible redox reaction, with a fast heterogeneous electron transfer rate of 7.98 ± 0.6 s −1 . The glucose biosensor showed a broad linear range up to 3.97 mM with high sensitivity of 62.45 μA·mM −1 cm −2 and fast response (less than 5 s). - Graphical abstract: Core-shell structured Fe 3 O 4 -silica-Au nanoparticles were prepared and used as matrix to construct an amperometric glucose sensor based on glucose oxidase, which showed broad linear range, high sensitivity, and fast response. Highlights: ► Synthesis of monodispersed Fe 3 O 4 nanoparticles. ► Fabrication of core/shell Fe 3 O 4 -silica-Au nanoparticles. ► Construction of a novel glucose sensor with wide linear range, high sensitivity and fast response.

Selection of nanoparticles using CO.sub.2-expanded liquids

Science.gov (United States)

Roberts, Christopher B; McLeod, Marshall Chandler; Anand, Madhu

2013-02-19

A method for size selection of nanostructures comprising utilizing a gas-expanded liquids (GEL) and controlled pressure to precipitate desired size populations of nanostructures, e.g., monodisperse. The GEL can comprise CO.sub.2 antisolvent and an organic solvent. The method can be carried out in an apparatus comprising a first open vessel configured to allow movement of a liquid/particle solution to specific desired locations within the vessel, a second pressure vessel, a location controller for controlling location of the particles and solution within the first vessel, a inlet for addition of antisolvent to the first vessel, and a device for measuring the amount of antisolvent added. Also disclosed is a method for forming nanoparticle thin films comprising utilizing a GEL containing a substrate, pressurizing the solution to precipitate and deposit nanoparticles onto the substrate, removing the solvent thereby leaving a thin nanoparticle film, removing the solvent and antisolvent, and drying the film.

Magnetic and structural characterizations on nanoparticles of FePt, FeRh and their composites

International Nuclear Information System (INIS)

Ko, Hnin Yu Yu; Suzuki, Takao; Nam, Nguyen T.; Phuoc, Nguyen N.; Cao Jiangwei; Hirotsu, Yoshihiko

2008-01-01

The various compositions of FePt and FeRh nanoparticles, and their composite particles have been fabricated by the solution-phase chemical method and their magnetic properties characterized. High-resolution transmission electron microscopic observations indicate that mono-dispersed FeRh and FePt/FeRh nanoparticles are fabricated with the average size of 3-5 nm. However, larger size particles are distributed in the annealed state. From X-ray diffraction results, the as-deposited FeRh nanoparticles reveal a chemically disordered fcc structure which can be transformed into CsCl-type structure through thermal annealing. Similarly, the annealed FePt nanoparticles show the L1 0 -phase fct structure although the fcc structure is apparent in the as-deposited state. It is also found that the first time in the exchange bias effect in the composite of ferromagnetic (FePt) and anti-ferromagnetic (FeRh) nanoparticles; result in a shift of the hysteresis loop after field cooling process

Characterization of a monodispersed aerosol exposure system for beagle dogs

International Nuclear Information System (INIS)

Cannon, W.C.; Herring, J.P.; Craig, D.K.

1978-01-01

A monodispersed aerosol exposure system for dogs is described and data are presented on aerosol depositions in the exposure system which could affect the aerosol presented to the animals by reducing the concentration and changing the particle size distribution

A general approach for monodisperse colloidal perovskites, Chemistry of Materials

NARCIS (Netherlands)

Demirors, A.F.; Imhof, A.

2009-01-01

We describe a novel general method for synthesizing monodisperse colloidal perovskite particles at room temperature by postsynthesis addition of metal hydroxides to amorphous titania colloids. In previous work, we used titania particles to synthesize homogenously mixed silica-titania composite

Green synthesis and antimicrobial activity of monodisperse silver nanoparticles synthesized using Ginkgo Biloba leaf extract

Science.gov (United States)

Ren, Yan-yu; Yang, Hui; Wang, Tao; Wang, Chuang

2016-11-01

Various parts of plants can be used as a raw material for the synthesis of nanoparticles, which is eco-friendly way and does not involve any harmful chemicals. In this project, Ginkgo biloba leaf, an abundantly available medicinal plant in China, was for the first time adopted as a reducing and stabilizing agent to synthesize smaller sized and stable silver nanoparticles (AgNPs). To improve the quality of AgNPs, the reduction was accelerated by changing the concentrations of initial Ag+ (0.02, 0.04, 0.06 and 0.08 mol/L) of the reaction mixture consisting of silver nitrate solution (AgNO3) and Ginkgo biloba leaf extract. At pH = 8 and lower AgNO3 concentration (0.02 mol/L), a colloid consisting of well-dispersed spherical nanoparticles was obtained. The synthesized nanocrystals were successfully characterized by UV-vis and XRD. TEM images revealed the size of the spherical AgNPs ranged between 10-16 nm. FTIR analysis revealed that biological macromolecules with groups of sbnd NH2, sbnd OH, and others were distributed on the surface of the nanoparticles. The biosynthesized AgNPs exhibited good antibacterial activities against gram-negative bacteria and gram-positive bacteria. Compared to traditional chemical methods, Ginkgo biloba leaf extract provides an easy green synthetical way. It is anticipated that the biosynthesized AgNPs can be used in areas such as cosmetics, foods and medical applications.

The effectiveness of the biodegradation of raw and processed polystyrene by mealworms

Science.gov (United States)

Leluk, Karol; Hanus-Lorenz, Beata; Rybak, Justyna; Bożek, Magdalena

2017-11-01

In our studies biodegradation of four variants of polystyrene was performed. We tested: raw material (PS), processed polystyrene (PSr), building insulation material (EPS) and food packaging boxes (PSp). Materials were characterized by means melt flow ratio (MFR), shore hardness and gloss. The biochemical assessment of macromolecules (proteins, lipids and sugars) in the mealworms organisms fed with tested forms of polystyrene allowed us to set how efficient and beneficial the biodegradation of types of polystyrene is. We also evaluated the variability of bacterial community in larval guts by the use of denaturing gradient gel electrophoresis (DGGE) on the bacterial DNA of 16S rRNA genes amplified in polymerase chain reaction (PCR). The results suggest that EPS and PSp polystyrene are the most digestible for T. molitor larvae. The metabolic degradation of polystyrene is probably strictly connected with the changes in biodiversity of gut bacteria.

The effectiveness of the biodegradation of raw and processed polystyrene by mealworms

Directory of Open Access Journals (Sweden)

Leluk Karol

2017-01-01

Full Text Available In our studies biodegradation of four variants of polystyrene was performed. We tested: raw material (PS, processed polystyrene (PSr, building insulation material (EPS and food packaging boxes (PSp. Materials were characterized by means melt flow ratio (MFR, shore hardness and gloss. The biochemical assessment of macromolecules (proteins, lipids and sugars in the mealworms organisms fed with tested forms of polystyrene allowed us to set how efficient and beneficial the biodegradation of types of polystyrene is. We also evaluated the variability of bacterial community in larval guts by the use of denaturing gradient gel electrophoresis (DGGE on the bacterial DNA of 16S rRNA genes amplified in polymerase chain reaction (PCR. The results suggest that EPS and PSp polystyrene are the most digestible for T. molitor larvae. The metabolic degradation of polystyrene is probably strictly connected with the changes in biodiversity of gut bacteria.

Structural investigations on differently sized monodisperse iron oxide nanoparticles synthesized by remineralization of apoferritin molecules

International Nuclear Information System (INIS)

Ullrich, Aladin; Horn, Siegfried

2013-01-01

We have investigated the structure of iron oxide nanoparticles produced by remineralization and thermal treatment of horse spleen apoferritin molecules. The described procedure allows to synthesize particles with diameters ranging from 4 to 7 nm in size. Atomic force microscopy and transmission electron microscopy (TEM) investigations were performed for shape and size determination, whereas energy-dispersive X-ray (TEM-EDX), high-resolution TEM, and electron diffraction measurements revealed the chemical composition and crystal structure of the particles. We found predominantly single crystalline nanoparticles with a hematite-like (α-Fe 2 O 3 ) structure

Mortar modified with sulfonated polystyrene produced from waste plastic cups

OpenAIRE

MOTTA,L. A. C.; VIEIRA,J. G.; OMENA,T. H.; FARIA,F. A. C.; RODRIGUES FILHO,G.; ASSUNÇÃO,R. M. N.

2016-01-01

Abstract In this work, we studied the addition of sulfonated polystyrene produced from waste plastic cups as an admixture for mortars. Mortars were analyzed with polystyrene content of 0.0; 0.2; 0.6; 1.0 and 1.4% in relation to the cement mass. The influence of polystyrene on the mortars' properties was evaluated by the consistency index, water retention, water absorption, porosity, elasticity modulus, compressive strength, flexural strength, bond tensile strength and microscopy. The increase...

Field efficacy of expanded polystyrene and shredded waste polystyrene beads for mosquito control in artificial pools and field trials, Islamic Republic of Iran.

Science.gov (United States)

Soltani, A; Vatandoost, H; Jabbari, H; Mesdaghinia, A R; Mahvi, A H; Younesian, M; Hanafi-Bojd, A A; Bozorgzadeh, S

2012-10-01

Concerns about traditional chemical pesticides has led to increasing research into novel mosquito control methods. This study compared the effectiveness of 2 different types of polystyrene beads for control of mosquito larvae in south-east Islamic Republic of Iran. Simulated field trials were done in artificial pools and field trials were carried out in 2 villages in an indigenous malaria area using WHO-recommended methods. Application of expanded polystyrene beads or shredded, waste polystyrene chips to pool surfaces produced a significant difference between pre-treatment and post-treatment density of mosquitoes (86% and 78% reduction respectively 2 weeks after treatment). There was no significant difference between the efficacy of the 2 types of material. The use of polystyrene beads as a component of integrated vector management with other supportive measures could assist in the control of mosquito-borne diseases in the Islamic Republic of Iran and neighbouring countries.

Comparative ecotoxicity of polystyrene nanoparticles in natural seawater and reconstituted seawater using the rotifer Brachionus plicatilis.

Science.gov (United States)

Manfra, L; Rotini, A; Bergami, E; Grassi, G; Faleri, C; Corsi, I

2017-11-01

The impact of nanoplastics using model polystyrene nanoparticles (PS NPs), anionic (PS-COOH) and cationic (PS-NH 2 ), has been investigated on the marine rotifer Brachionus plicatilis, a major component of marine zooplanktonic species. The role of different surface charges in affecting PS NP behaviour and toxicity has been considered in high ionic strength media. To this aim, the selected media were standardized reconstituted seawater (RSW) and natural sea water (NSW), the latter resembling more natural exposure scenarios. Hatched rotifer larvae were exposed for 24h and 48h to both PS NPs in the range of 0.5-50μg/ml using PS NP suspensions made in RSW and NSW. No effects on lethality upon exposure to anionic NPs were observed despite a clear gut retention was evident in all exposed rotifers. On the contrary, cationic NPs caused lethality to rotifer larvae but LC 50 values resulted lower in rotifers exposed in RSW (LC 50 =2.75±0.67µg/ml) compared to those exposed in NSW (LC 50 =6.62±0.87µg/ml). PS NPs showed similar pattern of aggregation in both high ionic strength media (RSW and NSW) but while anionic NPs resulted in large microscale aggregates (Z-average 1109 ± 128nm and 998±67nm respectively), cationic NP aggregates were still in nano-size forms (93.99 ± 11.22nm and 108.3 ± 12.79nm). Both PDI and Z-potential of PS NPs slightly differed in the two media suggesting a role of their different surface charges in affecting their behaviour and stability. Our findings confirm the role of surface charges in nanoplastic behaviour in salt water media and provide a first evidence of a different toxicity in rotifers using artificial media (RSW) compared to natural one (NSW). Such evidence poses the question on how to select the best medium in standardized ecotoxicity assays in order to properly assess their hazard to marine life in natural environmental scenarios. Copyright © 2017 Elsevier Inc. All rights reserved.

Biosynthesis of zinc oxide nanoparticles using leaf extract of Calotropis gigantea: characterization and its evaluation on tree seedling growth in nursery stage

Science.gov (United States)

Chaudhuri, Sadhan Kumar; Malodia, Lalit

2017-11-01

Green synthesis of zinc oxide nanoparticles was carried out using Calotropis leaf extract with zinc acetate salt in the presence of 2 M NaOH. The combination of 200 mM zinc acetate salt and 15 ml of leaf extract was ideal for the synthesis of less than 20 nm size of highly monodisperse crystalline nanoparticles. Synthesized nanoparticles were characterized through UV-Vis spectroscopy, dynamic light scattering (DLS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), EDX (energy dispersive X-ray), and AFM (atomic force microscopy). Effects of biogenic zinc oxide (ZnO) nanoparticles on growth and development of tree seedlings in nursery stage were studied in open-air trenches. The UV-Vis absorption maxima showed peak near 350 nm, which is characteristic of ZnO nanoparticles. DLS data showed that single peak is at 11 nm (100%) and Polydispersity Index is 0.245. XRD analysis showed that these are highly crystalline ZnO nanoparticles having an average size of 10 nm. FTIR spectra were recorded to identify the biomolecules involved in the synthesis process, which showed absorption bands at 4307, 3390, 2825, 871, 439, and 420 cm-1. SEM images showed that the particles were spherical in nature. The presence of zinc and oxygen was confirmed by EDX and the atomic % of zinc and oxygen were 33.31 and 68.69, respectively. 2D and 3D images of ZnO nanoparticles were obtained by AFM studies, which indicated that these are monodisperse having size ranges between 1.5 and 8.5 nm. Significant enhancement of growth was observed in Neem ( Azadirachta indica), Karanj ( Pongamia pinnata), and Milkwood-pine ( Alstonia scholaris) seedlings in foliar spraying ZnO nanoparticles to nursery stage of tree seedlings. Out of the three treated saplings, Alstonia scholaris showed maximum height development.

The polymerization of aniline in polystyrene latex particles

Czech Academy of Sciences Publication Activity Database

Blinova, Natalia V.; Reynaud, S.; Roby, F.; Trchová, Miroslava; Stejskal, Jaroslav

2010-01-01

Roč. 160, 15/16 (2010), s. 1598-1602 ISSN 0379-6779 R&D Projects: GA AV ČR IAA400500905; GA ČR GA203/08/0686; GA ČR GA202/09/1626 Institutional research plan: CEZ:AV0Z40500505 Keywords : polyaniline * polystyrene latex * polyaniline-polystyrene composite Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.871, year: 2010

Selective porous gates made from colloidal silica nanoparticles

Directory of Open Access Journals (Sweden)

Roberto Nisticò

2015-11-01

Full Text Available Highly selective porous films were prepared by spin-coating deposition of colloidal silica nanoparticles on an appropriate macroporous substrate. Silica nanoparticles very homogenous in size were obtained by sol–gel reaction of a metal oxide silica precursor, tetraethyl orthosilicate (TEOS, and using polystyrene-block-poly(ethylene oxide (PS-b-PEO copolymers as soft-templating agents. Nanoparticles synthesis was carried out in a mixed solvent system. After spin-coating onto a macroporous silicon nitride support, silica nanoparticles were calcined under controlled conditions. An organized nanoporous layer was obtained characterized by a depth filter-like structure with internal porosity due to interparticle voids. Permeability and size-selectivity were studied by monitoring the diffusion of probe molecules under standard conditions and under the application of an external stimulus (i.e., electric field. Promising results were obtained, suggesting possible applications of these nanoporous films as selective gates for controlled transport of chemical species in solution.

Quercetin and gallic acid mediated synthesis of bimetallic (silver and selenium) nanoparticles and their antitumor and antimicrobial potential.

Science.gov (United States)

Mittal, Amit Kumar; Kumar, Sanjay; Banerjee, Uttam Chand

2014-10-01

In this study a synthetic approach for the stable, mono-dispersed high yielding bimetallic (Ag-Se) nanoparticles by quercetin and gallic acid is described. The bimetallic nanoparticles were synthesized at room temperature. Different reaction parameters (concentration of quercetin, gallic acid and Ag/Se salt, pH, temperature and reaction time) were optimized to control the properties of nanoparticles. The nanoparticles were characterized by various analytical techniques and their size was determined to be 30-35 nm. Our findings suggest that both the reduction as well as stabilization of nanoparticles were achieved by the flavonoids and phenolics. This study describes the efficacy of quercetin and gallic acid mediated synthesis of bimetallic (Ag-Se) nanoparticles and their in vitro antioxidant, antimicrobial (Gram-positive and Gram-negative bacteria) and antitumor potentials. The synthesized Ag-Se nanoparticles were used as anticancer agents for Dalton lymphoma (DL) cells and in in vitro 80% of its viability was reduced at 50 μg/mL. Copyright © 2014 Elsevier Inc. All rights reserved.

Taylor dispersion of nanoparticles

Science.gov (United States)

Balog, Sandor; Urban, Dominic A.; Milosevic, Ana M.; Crippa, Federica; Rothen-Rutishauser, Barbara; Petri-Fink, Alke

2017-08-01

The ability to detect and accurately characterize particles is required by many fields of nanotechnology, including materials science, nanotoxicology, and nanomedicine. Among the most relevant physicochemical properties of nanoparticles, size and the related surface-to-volume ratio are fundamental ones. Taylor dispersion combines three independent phenomena to determine particle size: optical extinction, translational diffusion, and sheer-enhanced dispersion of nanoparticles subjected to a steady laminar flow. The interplay of these defines the apparent size. Considering that particles in fact are never truly uniform nor monodisperse, we rigorously address particle polydispersity and calculate the apparent particle size measured by Taylor dispersion analysis. We conducted case studies addressing aqueous suspensions of model particles and large-scale-produced "industrial" particles of both academic and commercial interest of various core materials and sizes, ranging from 15 to 100 nm. A comparison with particle sizes determined by transmission electron microscopy confirms that our approach is model-independent, non-parametric, and of general validity that provides an accurate account of size polydispersity—independently on the shape of the size distribution and without any assumption required a priori.

Surface chemistry of photoluminescent F8BT conjugated polymer nanoparticles determines protein corona formation and internalization by phagocytic cells.

Science.gov (United States)

Ahmad Khanbeigi, Raha; Abelha, Thais Fedatto; Woods, Arcadia; Rastoin, Olivia; Harvey, Richard D; Jones, Marie-Christine; Forbes, Ben; Green, Mark A; Collins, Helen; Dailey, Lea Ann

2015-03-09

Conjugated polymer nanoparticles are being developed for a variety of diagnostic and theranostic applications. The conjugated polymer, F8BT, a polyfluorene derivative, was used as a model system to examine the biological behavior of conjugated polymer nanoparticle formulations stabilized with ionic (sodium dodecyl sulfate; F8BT-SDS; ∼207 nm; -31 mV) and nonionic (pegylated 12-hydroxystearate; F8BT-PEG; ∼175 nm; -5 mV) surfactants, and compared with polystyrene nanoparticles of a similar size (PS200; ∼217 nm; -40 mV). F8BT nanoparticles were as hydrophobic as PS200 (hydrophobic interaction chromatography index value: 0.96) and showed evidence of protein corona formation after incubation with serum-containing medium; however, unlike polystyrene, F8BT nanoparticles did not enrich specific proteins onto the nanoparticle surface. J774A.1 macrophage cells internalized approximately ∼20% and ∼60% of the F8BT-SDS and PS200 delivered dose (calculated by the ISDD model) in serum-supplemented and serum-free conditions, respectively, while cell association of F8BT-PEG was minimal (<5% of the delivered dose). F8BT-PEG, however, was more cytotoxic (IC50 4.5 μg cm(-2)) than F8BT-SDS or PS200. The study results highlight that F8BT surface chemistry influences the composition of the protein corona, while the properties of the conjugated polymer nanoparticle surfactant stabilizer used determine particle internalization and biocompatibility profile.

Photoelectrochemical sensors for the rapid detection of DNA damage Induced by some nanoparticles

International Nuclear Information System (INIS)

Ahmed, M.J.; Zhang, B.T.; Guo, L.H.

2010-01-01

Photoelectrochemical sensors were developed for the rapid detection of oxidative DNA damage induced by titanium dioxide and polystyrene nanoparticles. Each sensor is a multilayer film prepared on a tin oxide nanoparticle electrode using layer- by-layer self assembly and is composed of separate layer of a photoelectrochemical indicator, DNA. The organic compound and heavy metals represent genotoxic chemicals leading two major damaging mechanisms, DNA adduct formation and DNA oxidation. The DNA damage is detected by monitoring the change of photocurrent of the indicator. In one sensor configuration, a DNA intercalator, Ru(bpy)2 (dppz)2+ [bpy=2, 2' -bipyridine, dppz=dipyrido (3, 2-a: 2' 3'-c) phenazine], was employed as the photoelectrochemical indicator. The damaged DNA on the sensor bound lesser Ru(bpy)2 (dppz)2+ than the intact DNA, resulting in a drop in photocurrent. In another configuration, ruthenium tris(bipyridine) was used as the indicator and was immobilized on the electrode underneath the DNA layer. After oxidative damage, the DNA bases became more accessible to photoelectrochemical oxidation than the intact DNA, producing a rise in photocurrent. Both sensors displayed substantial photocurrent change after incubation in titanium dioxide / polystyrene solution in a time . dependent manner. According to the data, damage of the DNA film was completed in 1h in titanium dioxide / polystyrene solution. In addition, the titanium dioxide induced much more sever damage than polystyrene. The results were verified independently by gel electrophoresis and UV-Vis absorbance experiments. The photoelectrochemical reaction can be employed as a new and inexpensive screening tool for the rapid assessment of the genotoxicity of existing and new chemicals. (author)

Glucan Particles for Macrophage Targeted Delivery of Nanoparticles

Directory of Open Access Journals (Sweden)

Ernesto R. Soto

2012-01-01

Full Text Available Glucan particles (GPs are hollow, porous 2–4 μm microspheres derived from the cell walls of Baker's yeast (Saccharomyces cerevisiae. The 1,3-β-glucan outer shell provides for receptor-mediated uptake by phagocytic cells expressing β-glucan receptors. GPs have been used for macrophage-targeted delivery of soluble payloads (DNA, siRNA, protein, and small molecules encapsulated inside the hollow GPs via core polyplex and layer-by-layer (LbL synthetic strategies. In this communication, we report the incorporation of nanoparticles as cores inside GPs (GP-NP or electrostatically bound to the surface of chemically derivatized GPs (NP-GP. GP nanoparticle formulations benefit from the drug encapsulation properties of NPs and the macrophage-targeting properties of GPs. GP nanoparticle formulations were synthesized using fluorescent anionic polystyrene nanoparticles allowing visualization and quantitation of NP binding and encapsulation. Mesoporous silica nanoparticles (MSNs containing the chemotherapeutic doxorubicin (Dox were bound to cationic GPs. Dox-MSN-GPs efficiently delivered Dox into GP phagocytic cells resulting in enhanced Dox-mediated growth arrest.

Silver Nanoparticle-Decorated Shape-Memory Polystyrene Sheets as Highly Sensitive Surface-Enhanced Raman Scattering Substrates with a Thermally Inducible Hot Spot Effect.

Science.gov (United States)

Mengesha, Zebasil Tassew; Yang, Jyisy

2016-11-15

In this study, an active surface-enhanced Raman scattering (SERS) substrate with a thermally inducible hot spot effect for sensitive measurement of Raman-active molecules was successfully fabricated from silver nanoparticle (AgNP)-decorated shape-memory polystyrene (SMP) sheets. To prepare the SERS substrate, SMP sheets were first pretreated with n-octylamine for effective decoration with AgNPs. By varying the formulation and condition of the reduction reaction, AgNP-decorated SMP (Ag@SMP) substrates were successfully prepared with optimized particle gaps to produce inducible hot spot effects on thermal shrink. High-quality SERS spectra were easily obtained with enhancement factors higher than 10 8 by probing with aromatic thiols. Several Ag@SMP substrates produced under different reaction conditions were explored for the creation of inducible hot spot effects. The results indicated that AgNP spacing is crucial for strong hot spot effects. The suitability of Ag@SMP substrates for quantification was also evaluated according to the detection of adenine. Results confirmed that prepared Ag@SMP substrates were highly suitable for quantitative analysis because they yielded an estimated limit of detection as low as 120 pg/cm 2 , a linear range of up to 7 ng/cm 2 , and a regression coefficient (R 2 ) of 0.9959. Ag@SMP substrates were highly reproducible; the average relative standard deviation for all measurements was less than 10%.

Minimising the effect of nanoparticle deformation in intermittent contact amplitude modulation atomic force microscopy measurements

International Nuclear Information System (INIS)

Babic, Bakir; Lawn, Malcolm A.; Coleman, Victoria A.; Jämting, Åsa K.; Herrmann, Jan

2016-01-01

The results of systematic height measurements of polystyrene (PS) nanoparticles using intermittent contact amplitude modulation atomic force microscopy (IC-AM-AFM) are presented. The experimental findings demonstrate that PS nanoparticles deform during AFM imaging, as indicated by a reduction in the measured particle height. This deformation depends on the IC-AM-AFM imaging parameters, material composition, and dimensional properties of the nanoparticles. A model for nanoparticle deformation occurring during IC-AM-AFM imaging is developed as a function of the peak force which can be calculated for a particular set of experimental conditions. The undeformed nanoparticle height can be estimated from the model by extrapolation to zero peak force. A procedure is proposed to quantify and minimise nanoparticle deformation during IC-AM-AFM imaging, based on appropriate adjustments of the experimental control parameters.

Minimising the effect of nanoparticle deformation in intermittent contact amplitude modulation atomic force microscopy measurements

Energy Technology Data Exchange (ETDEWEB)

Babic, Bakir, E-mail: bakir.babic@measurement.gov.au; Lawn, Malcolm A.; Coleman, Victoria A.; Jämting, Åsa K.; Herrmann, Jan [National Measurement Institute, 36 Bradfield Road, West Lindfield, New South Wales 2070 (Australia)

2016-06-07

The results of systematic height measurements of polystyrene (PS) nanoparticles using intermittent contact amplitude modulation atomic force microscopy (IC-AM-AFM) are presented. The experimental findings demonstrate that PS nanoparticles deform during AFM imaging, as indicated by a reduction in the measured particle height. This deformation depends on the IC-AM-AFM imaging parameters, material composition, and dimensional properties of the nanoparticles. A model for nanoparticle deformation occurring during IC-AM-AFM imaging is developed as a function of the peak force which can be calculated for a particular set of experimental conditions. The undeformed nanoparticle height can be estimated from the model by extrapolation to zero peak force. A procedure is proposed to quantify and minimise nanoparticle deformation during IC-AM-AFM imaging, based on appropriate adjustments of the experimental control parameters.

Synthesis of Specific Nanoparticles for Targeting and Imaging Tumor Angiogenesis Using Electron-Beam Irradiation

Energy Technology Data Exchange (ETDEWEB)

Rizza, G.; Deshayes, S.; Maurizot, V.; Clochard, M. -C.; Berthelot, T.; Baudin, C.; Déléris, G., E-mail: giancarlo.rizza@polytechnique.edu [Commissariat à l' énergie atomique (CEA), Institut Rayonnement Matière de Saclay (IRaMIS), B.P. 52, 91191 Gif Sur Yvette Cedex (France)

2010-07-01

We have succeeded to synthesize PVDF nanoparticles by nanoemulsion polymerization and their functionalization with a peptide that presents an anti-angiogenic activity. Resulted nanoparticles present a radius of 60 nm. From FESEM images and light scattering measurements, we deduced that they were spherical and monodisperse. The alkyl radicals induced from electron beam irradiation combine immediately with the oxygen to form peroxide radicals. Because of a high specific area and small crystallite size, the radical decay with time is evidenced from EPR measurements. Despite this radical decay, electron beam irradiation allows us to graft PAA by radical polymerization onto freshly irradiated PVDF nanoparticles and then to immobilize CBO-P11 by click chemistry via a spacer arm. Evidences of grafting were shown using HRMAS NMR and MALDI-TOF mass spectrometry. Nanoparticles functionalized with an angiogenesis-targeting agent are an attractive option for anti-tumor therapy.

Synthesis of Specific Nanoparticles for Targeting and Imaging Tumor Angiogenesis Using Electron-Beam Irradiation

International Nuclear Information System (INIS)

Rizza, G.; Deshayes, S.; Maurizot, V.; Clochard, M.-C.; Berthelot, T.; Baudin, C.; Déléris, G.

2010-01-01

We have succeeded to synthesize PVDF nanoparticles by nanoemulsion polymerization and their functionalization with a peptide that presents an anti-angiogenic activity. Resulted nanoparticles present a radius of 60 nm. From FESEM images and light scattering measurements, we deduced that they were spherical and monodisperse. The alkyl radicals induced from electron beam irradiation combine immediately with the oxygen to form peroxide radicals. Because of a high specific area and small crystallite size, the radical decay with time is evidenced from EPR measurements. Despite this radical decay, electron beam irradiation allows us to graft PAA by radical polymerization onto freshly irradiated PVDF nanoparticles and then to immobilize CBO-P11 by click chemistry via a spacer arm. Evidences of grafting were shown using HRMAS NMR and MALDI-TOF mass spectrometry. Nanoparticles functionalized with an angiogenesis-targeting agent are an attractive option for anti-tumor therapy

Synthesis and characterization of polystyrene coated iron oxide nanoparticles and asymmetric assemblies by phase inversion

KAUST Repository

Xie, Yihui; Sougrat, Rachid; Nunes, Suzana Pereira

2014-01-01

nanoparticle assemblies were then prepared by solution casting and immersion in water. The nanocomposite film production with functionalized nanoparticles is fast and technically scalable. The morphologies of films were characterized by scanning electron

Solvent effect on polystyrene surface roughness on top of QCM sensor

Energy Technology Data Exchange (ETDEWEB)

Sakti, Setyawan P., E-mail: sakti@ub.ac.id; Rahmawati, Eka; Robiandi, Fadli [Advanced System and Material Technology, Laboratory of Instrumentation and Measurement Department of Physics, Brawijaya University (Indonesia)

2016-03-11

Quartz Crystal Microbalance (QCM) has been used as a basis for many chemical sensors and biosensor. Its sensitivity to mass change which can detect a mass change on its surface down to sub ng/cm2 is one of its interesting aspects. Another interesting feature is its ability to work in liquid environment. However, there are many aspects which influence QCM sensor properties in contact with liquid. One of the aspects is surface roughness of the matrix layer where on top of it a biological sensitive layer will be immobilized. One of matrix layers in the immobilizing biological sensitive layer was polystyrene. Polystyrene was coated on the QCM sensor by using the spin coating method. During the coating process, polystyrene was solved using non-polar solvent. It is known that the physical and chemical properties of the solvent affect a transition process from soluble polymer becoming rigid polymer layer. In this work, we show that polystyrene solved in chloroform has a higher surface roughness compare to one solved in toluene, xylene, or tetrahydrofuran. Surface roughness of the polystyrene coating were measured using a non-contact profilometer. However, we also found that there is no difference on the electrical impedance of the QCM sensor coated with polystyrene resulted from differing solvent when the sensor was in contact with air and water. Thus, all of the mentioned solvent can be used to solve the polystyrene as a coating material for QCM sensor without affecting the electrical performance of the sensor, but the choice of the solution can be used as a simple method to control the difference roughness of the polystyrene coating.

Adenosine monophosphate is elevated in the bronchoalveolar lavage fluid of mice with acute respiratory toxicity induced by nanoparticles with high surface hydrophobicity.

Science.gov (United States)

Dailey, Lea Ann; Hernández-Prieto, Raquel; Casas-Ferreira, Ana Maria; Jones, Marie-Christine; Riffo-Vasquez, Yanira; Rodríguez-Gonzalo, Encarnación; Spina, Domenico; Jones, Stuart A; Smith, Norman W; Forbes, Ben; Page, Clive; Legido-Quigley, Cristina

2015-02-01

Inhaled nanomaterials present a challenge to traditional methods and understanding of respiratory toxicology. In this study, a non-targeted metabolomics approach was used to investigate relationships between nanoparticle hydrophobicity, inflammatory outcomes and the metabolic fingerprint in bronchoalveolar fluid. Measures of acute lung toxicity were assessed following single-dose intratracheal administration of nanoparticles with varying surface hydrophobicity (i.e. pegylated lipid nanocapsules, polyvinyl acetate nanoparticles and polystyrene beads; listed in order of increasing hydrophobicity). Broncho-alveolar lavage (BAL) fluid was collected from mice exposed to nanoparticles at a surface area dose of 220 cm(2) and metabolite fingerprints were acquired via ultra pressure liquid chromatography-mass spectrometry-based metabolomics. Particles with high surface hydrophobicity were pro-inflammatory. Multivariate analysis of the resultant small molecule fingerprints revealed clear discrimination between the vehicle control and polystyrene beads (p < 0.05), as well as between nanoparticles of different surface hydrophobicity (p < 0.0001). Further investigation of the metabolic fingerprints revealed that adenosine monophosphate (AMP) concentration in BAL correlated with neutrophilia (p < 0.01), CXCL1 levels (p < 0.05) and nanoparticle surface hydrophobicity (p < 0.001). Our results suggest that extracellular AMP is an intermediary metabolite involved in adenine nucleotide-regulated neutrophilic inflammation as well as tissue damage, and could potentially be used to monitor nanoparticle-induced responses in the lung following pulmonary administration.

Room temperature vortex fluidic synthesis of monodispersed amorphous proto-vaterite.

Science.gov (United States)

Peng, Wenhong; Chen, Xianjue; Zhu, Shenmin; Guo, Cuiping; Raston, Colin L

2014-10-11

Monodispersed particles of amorphous calcium carbonate (ACC) 90 to 200 nm in diameter are accessible at room temperature in ethylene glycol and water using a vortex fluidic device (VFD). The ACC material is stable for at least two weeks under ambient conditions.

Ultrasound-driven Megahertz Faraday Waves for Generation of Monodisperse Micro Droplets and Applications

Science.gov (United States)

Tsai, Chen S.; Mao, Rong W.; Lin, Shih K.; Tsai, Shirley C.; Boss, Gerry; Brenner, Matt; Smaldone, Gerry; Mahon, Sari; Shahverdi, Kaveh; Zhu, Yun

Our theoretical findings on instability of Faraday waves at megahertz (MHz) drive frequency and realization of silicon-based MHz multiple-Fourier horn ultrasonic nozzles (MFHUNs) together have enabled generation of mono-disperse droplets of controllable diameter (2.5-6.0 μm) at very low electrical drive power (generator has imminent application to pulmonary (inhalation) drug delivery and other potential applications. Here an update of advances on analysis and design of the MHz MFHUNs and the underlying physical mechanism for generation of mono-disperse micro droplets, and the nebulizer platform for application to detoxification of cyanide poisoning are presented.

Synthesis, characterization and antibacterial study on the chitosan-functionalized Ag nanoparticles.

Science.gov (United States)

Biao, Linhai; Tan, Shengnan; Wang, Yuanlin; Guo, Ximin; Fu, Yujie; Xu, Fengjie; Zu, Yuangang; Liu, Zhiguo

2017-07-01

This study provided a facile, one-step hydrothermal method to synthesize stable Ag colloid in aqueous solution by utilizing chitosan as both reductant and stabilizer. The formation of chitosan-functionalized Ag nanoparticles was verified by UV-Vis, FTIR, TEM, AFM and XRD measurements. FTIR results revealed that the primary amine groups and amide groups of chitosan have specific interactions with the surface of Ag nanoparticles. The average diameter of the Ag nanoparticles is 10.0±5.4nm as determined by TEM. Ag nanoparticles are highly crystalline as revealed by HR-TEM and XRD measurements. The size and shape of Ag nanoparticles are also found to depend on the pH condition in the synthesis. Ag nanoparticles were the main products at pH5.0 whereas large Ag nanotriangle and truncated triangular nanoplate were dominant at pH4.0 in the synthesis. Due to its monodispersity and good stability, the chitosan-functionalized Ag colloid synthesized at pH5.0 was further tested for its antibacterial activities against gram-positive bacteria, gram-negative bacteria and fungus. The results of zone of inhibition, inhibition ratio and SEM characterization revealed that chitosan-functionalized Ag nanoparticles have great bactericidal efficiency against both bacteria and fungus. Copyright © 2017 Elsevier B.V. All rights reserved.

The surface modification of polystyrene

International Nuclear Information System (INIS)

Tremlett, C.

2000-03-01

Polymers have ideal bulk properties for many applications. However, adhesion to many polymers is poor without surface pretreatment. This can result, for example, in peeling paint and printing, adhesive joint failure and bio-incompatibility. In applications such as painting, printing, adhesive bonding and biocompatibility, various cleaning or surface chemical modifications may be employed. A commodity polymer where pretreatment is sometimes needed is polystyrene. This project investigated, in detail, the effects of a novel method of modification namely mediated electrochemical oxidation (MEO), as a mode of surface modification on polystyrene and a comparison was made with other polymers. The resulting modification was investigated using a range of surface analysis techniques to obtain complementary information. These included, X-ray photoelectron spectroscopy, contact angles, static secondary ion mass spectrometry, atomic force microscopy, chemical derivatization, scanning electron microscopy, attenuated total reflection Fourier Transform infrared spectroscopy and composite lap shear joint testing. It has been shown that MEO modifies the surface of polystyrene introduced oxygen mainly as hydroxyl groups, and a small number of carbonyl groups, that are positioned only on the backbone hydrocarbon chain. This modification improved adhesion, was stable and samples could be stored in aqueous media. The resulting hydroxylation was further derivatized using an amino acid to provide a specialised surface. This was very different from the multiple oxygen functionalities introduced in the comparison studies by UV/ozone and plasma treatments. (author)

Extruded expanded polystyrene sheets coated by TiO{sub 2} as new photocatalytic materials for foodstuffs packaging

Energy Technology Data Exchange (ETDEWEB)

Loddo, V.; Marci, G. [Schiavello-Grillone Photocatalysis Group - Dipartimento di Ingegneria Elettrica, Elettronica e delle Telecomunicazioni, di tecnologie Chimiche, Automatica e modelli Matematici - Universita degli Studi di Palermo, Viale delle Scienze (Ed. 6) - 90128 Palermo (Italy); Palmisano, G., E-mail: giovanni_palmisano@yahoo.it [Schiavello-Grillone Photocatalysis Group - Dipartimento di Ingegneria Elettrica, Elettronica e delle Telecomunicazioni, di tecnologie Chimiche, Automatica e modelli Matematici - Universita degli Studi di Palermo, Viale delle Scienze (Ed. 6) - 90128 Palermo (Italy); Yurdakal, S. [Kimya Boeluemue, Fen-Edebiyat Fakueltesi, Afyon Kocatepe Ueniversitesi - Ahmet Necdet Sezer Kampuesue - 03200 Afyon (Turkey); Brazzoli, M.; Garavaglia, L. [Sirap-Gema S.p.A. - Via Industriale, 1/3 - 25028 Verolanuova (Brescia) (Italy); Palmisano, L., E-mail: leonardo.palmisano@unipa.it [Schiavello-Grillone Photocatalysis Group - Dipartimento di Ingegneria Elettrica, Elettronica e delle Telecomunicazioni, di tecnologie Chimiche, Automatica e modelli Matematici - Universita degli Studi di Palermo, Viale delle Scienze (Ed. 6) - 90128 Palermo (Italy)

2012-11-15

Highlights: Black-Right-Pointing-Pointer An extruded polystyrene has been functionalised by TiO{sub 2}. Black-Right-Pointing-Pointer A photocatalytic polymer has been developed via a sol-gel method. Black-Right-Pointing-Pointer Thermoformed packagings for foodstuffs application have been prepared. - Abstract: Nanostructured, photoactive anatase TiO{sub 2} sol prepared under very mild conditions using titanium tetraisopropoxide as the precursor is used to functionalise extruded expanded polystyrene (XPS) sheets by spray-coating resulting in stable and active materials functionalised by TiO{sub 2} nanoparticles. Photocatalytic tests of these sheets performed in a batch reactor in gas-solid system under UV irradiation show their successful activity in degrading probe molecules (2-propanol, trimethylamine and ethene). Raman spectra ensure the deposition of TiO{sub 2} as crystalline anatase phase on the polymer surface. The presence of TiO{sub 2} with respect to polymer surface can be observed in SEM images coupled to EDAX mapping allowing to monitor the surface morphology and the distribution of TiO{sub 2} particles. Finally thermoforming of these sheets in industrial standard equipment leads to useful containers for foodstuffs.

Enhanced sensitivity of a microfabricated resonator using a graphene-polystyrene bilayer membrane

Energy Technology Data Exchange (ETDEWEB)

Yun, Minhyuk; Lee, Eunho; Cho, Kilwon; Jeon, Sangmin, E-mail: jeons@postech.ac.kr [Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang (Korea, Republic of)

2014-08-18

A graphene layer was synthesized using chemical vapor deposition methods and a polystyrene solution was spin-cast onto the graphene film. The graphene-polystyrene bilayer membrane was attached between the two tines of a microfabricated quartz tuning fork (QTF). The modulus of the graphene-polystyrene bilayer was measured to be twice that of a pristine polystyrene membrane. Exposure of the membrane-coated QTF to ethanol vapor decreased the resonance frequency of the microresonator. The bilayer membrane-coated QTF produced a frequency change that was three times the change obtained using a polystyrene membrane-coated QTF, with a lower degree of degradation in the Q factor. The limit of detection of the bilayer membrane-coated QTF to ethanol vapor was determined to be 20 ppm.

The Study of the Microbes Degraded Polystyrene

Directory of Open Access Journals (Sweden)

Zhi-Long Tang

2017-01-01

Full Text Available Under the observation that Tenebrio molitor and Zophobas morio could eat polystyrene (PS, we setup the platform to screen the gut microbes of these two worms. To take advantage of that Tenebrio molitor and Zophobas morio can eat and digest polystyrene as its diet, we analyzed these special microbes with PS plate and PS turbidity system with time courses. There were two strains TM1 and ZM1 which isolated from Tenebrio molitor and Zophobas morio, and were identified by 16S rDNA sequencing. The results showed that TM1 and ZM1 were cocci-like and short rod shape Gram-negative bacteria under microscope. The PS plate and turbidity assay showed that TM1 and ZM1 could utilize polystyrene as their carbon sources. The further study of PS degraded enzyme and cloning warrants our attention that this platform will be an excellent tools to explore and solve this problem.

Fluoride loaded polymeric nanoparticles for dental delivery.

Science.gov (United States)

Nguyen, Sanko; Escudero, Carlos; Sediqi, Nadia; Smistad, Gro; Hiorth, Marianne

2017-06-15

The overall aim of the present paper was to develop fluoride loaded nanoparticles based on the biopolymers chitosan, pectin, and alginate, for use in dental delivery. First, the preparation of nanoparticles in the presence of sodium fluoride (NaF) as the active ingredient by ionic gelation was investigated followed by an evaluation of their drug entrapment and release properties. Chitosan formed stable, spherical, and monodisperse nanoparticles in the presence of NaF and tripolyphoshate as the crosslinker, whereas alginate and pectin were not able to form any definite nanostructures in similar conditions. The fluoride loading capacity was found to be 33-113ppm, and the entrapment efficiency 3.6-6.2% for chitosan nanoparticles prepared in 0.2-0.4% (w/w) NaF, respectively. A steady increase in the fluoride release was observed for chitosan nanoparticles prepared in 0.2% NaF both in pH5 and 7 until it reached a maximum at time point 4h and maintained at this level for at least 24h. Similar profiles were observed for formulations prepared in 0.4% NaF; however the fluoride was released at a higher level at pH5. The low concentration, but continuous delivery of fluoride from the chitosan nanoparticles, with possible expedited release in acidic environment, makes these formulations highly promising as dental delivery systems in the protection against caries development. Copyright © 2017 Elsevier B.V. All rights reserved.

Synthesis of Fe Nanoparticles Functionalized with Oleic Acid Synthesized by Inert Gas Condensation

Directory of Open Access Journals (Sweden)

L. G. Silva

2014-01-01

Full Text Available In this work, we study the synthesis of monodispersed Fe nanoparticles (Fe-NPs in situ functionalized with oleic acid. The nanoparticles were self-assembled by inert gas condensation (IGC technique by using magnetron-sputtering process. Structural characterization of Fe-NPs was performed by transmission electron microscopy (TEM. Particle size control was carried out through the following parameters: (i condensation zone length, (ii magnetron power, and (iii gas flow (Ar and He. Typically the nanoparticles generated by IGC showed diameters which ranged from ~0.7 to 20 nm. Mass spectroscopy of Fe-NPs in the deposition system allowed the study of in situ nanoparticle formation, through a quadrupole mass filter (QMF that one can use together with a mass filter. When the deposition system works without quadrupole mass filter, the particle diameter distribution is around +/−20%. When the quadrupole is in line, then the distribution can be reduced to around +/−2%.

A paclitaxel-loaded recombinant polypeptide nanoparticle outperforms Abraxane in multiple murine cancer models

Science.gov (United States)

Bhattacharyya, Jayanta; Bellucci, Joseph J.; Weitzhandler, Isaac; McDaniel, Jonathan R.; Spasojevic, Ivan; Li, Xinghai; Lin, Chao-Chieh; Chi, Jen-Tsan Ashley; Chilkoti, Ashutosh

2015-08-01

Packaging clinically relevant hydrophobic drugs into a self-assembled nanoparticle can improve their aqueous solubility, plasma half-life, tumour-specific uptake and therapeutic potential. To this end, here we conjugated paclitaxel (PTX) to recombinant chimeric polypeptides (CPs) that spontaneously self-assemble into ~60 nm near-monodisperse nanoparticles that increased the systemic exposure of PTX by sevenfold compared with free drug and twofold compared with the Food and Drug Administration-approved taxane nanoformulation (Abraxane). The tumour uptake of the CP-PTX nanoparticle was fivefold greater than free drug and twofold greater than Abraxane. In a murine cancer model of human triple-negative breast cancer and prostate cancer, CP-PTX induced near-complete tumour regression after a single dose in both tumour models, whereas at the same dose, no mice treated with Abraxane survived for >80 days (breast) and 60 days (prostate), respectively. These results show that a molecularly engineered nanoparticle with precisely engineered design features outperforms Abraxane, the current gold standard for PTX delivery.

PAMAM dendrimer-coated iron oxide nanoparticles: synthesis and characterization of different generations

International Nuclear Information System (INIS)

Khodadust, Rouhollah; Unsoy, Gozde; Yalcın, Serap; Gunduz, Gungor; Gunduz, Ufuk

2013-01-01

This study focuses on the synthesis and characterization of different generations (G 0 –G 7 ) of polyamidoamine (PAMAM) dendrimer-coated magnetic nanoparticles (DcMNPs). In this study, superparamagnetic iron oxide nanoparticles were synthesized by co-precipitation method. The synthesized nanoparticles were modified with aminopropyltrimethoxysilane for dendrimer coating. Aminosilane-modified MNPs were coated with PAMAM dendrimer. The characterization of synthesized nanoparticles was performed by X-ray diffraction, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), dynamic light scattering, and vibrating sample magnetometry (VSM) analyses. TEM images demonstrated that the DcMNPs have monodisperse size distribution with an average particle diameter of 16 ± 5 nm. DcMNPs were found to be superparamagnetic through VSM analysis. The synthesis, aminosilane modification, and dendrimer coating of iron oxide nanoparticles were validated by FTIR and XPS analyses. Cellular internalization of nanoparticles was studied by inverted light scattering microscopy, and cytotoxicity was determined by XTT analysis. Results demonstrated that the synthesized DcMNPs, with their functional groups, symmetry perfection, size distribution, improved magnetic properties, and nontoxic characteristics could be suitable nanocarriers for targeted cancer therapy upon loading with various anticancer agents.

Synthesis of Silica Nanoparticles by Sol-Gel: Size-Dependent Properties, Surface Modification, and Applications in Silica-Polymer Nano composites-A Review

International Nuclear Information System (INIS)

Ismail, A.R.; Vejayakumaran, P.

2012-01-01

Application of silica nanoparticles as fillers in the preparation of nano composite of polymers has drawn much attention, due to the increased demand for new materials with improved thermal, mechanical, physical, and chemical properties. Recent developments in the synthesis of monodispersed, narrow-size distribution of nanoparticles by sol-gel method provide significant boost to development of silica-polymer nano composites. This paper is written by emphasizing on the synthesis of silica nanoparticles, characterization on size-dependent properties, and surface modification for the preparation of homogeneous nano composites, generally by sol-gel technique. The effect of nano silica on the properties of various types of silica-polymer composites is also summarized.