Accurate Size and Size-Distribution Determination of Polystyrene Latex Nanoparticles in Aqueous Medium Using Dynamic Light Scattering and Asymmetrical Flow Field Flow Fractionation with Multi-Angle Light Scattering

PubMed Central

Kato, Haruhisa; Nakamura, Ayako; Takahashi, Kayori; Kinugasa, Shinichi

2012-01-01

Accurate determination of the intensity-average diameter of polystyrene latex (PS-latex) by dynamic light scattering (DLS) was carried out through extrapolation of both the concentration of PS-latex and the observed scattering angle. Intensity-average diameter and size distribution were reliably determined by asymmetric flow field flow fractionation (AFFFF) using multi-angle light scattering (MALS) with consideration of band broadening in AFFFF separation. The intensity-average diameter determined by DLS and AFFFF-MALS agreed well within the estimated uncertainties, although the size distribution of PS-latex determined by DLS was less reliable in comparison with that determined by AFFFF-MALS. PMID:28348293

Controllable Fabrication of Non-Close-Packed Colloidal Nanoparticle Arrays by Ion Beam Etching

NASA Astrophysics Data System (ADS)

Yang, Jie; Zhang, Mingling; Lan, Xu; Weng, Xiaokang; Shu, Qijiang; Wang, Rongfei; Qiu, Feng; Wang, Chong; Yang, Yu

2018-06-01

Polystyrene (PS) nanoparticle films with non-close-packed arrays were prepared by using ion beam etching technology. The effects of etching time, beam current, and voltage on the size reduction of PS particles were well investigated. A slow etching rate, about 9.2 nm/min, is obtained for the nanospheres with the diameter of 100 nm. The rate does not maintain constant with increasing the etching time. This may result from the thermal energy accumulated gradually in a long-time bombardment of ion beam. The etching rate increases nonlinearly with the increase of beam current, while it increases firstly then reach its saturation with the increase of beam voltage. The diameter of PS nanoparticles can be controlled in the range from 34 to 88 nm. Based on the non-close-packed arrays of PS nanoparticles, the ordered silicon (Si) nanopillars with their average diameter of 54 nm are fabricated by employing metal-assisted chemical etching technique. Our results pave an effective way to fabricate the ordered nanostructures with the size less than 100 nm.

One-step synthesis of amine-functionalized hollow mesoporous silica nanoparticles as efficient antibacterial and anticancer materials.

PubMed

Hao, Nanjing; Jayawardana, Kalana W; Chen, Xuan; Yan, Mingdi

2015-01-21

In this study, amine-functionalized hollow mesoporous silica nanoparticles with an average diameter of ∼100 nm and shell thickness of ∼20 nm were prepared by an one-step process. This new nanoparticulate system exhibited excellent killing efficiency against mycobacterial (M. smegmatis strain mc(2) 651) and cancer cells (A549).

In-situ synthesis of magnetic iron-oxide nanoparticle-nanofibre composites using electrospinning.

PubMed

Burke, Luke; Mortimer, Chris J; Curtis, Daniel J; Lewis, Aled R; Williams, Rhodri; Hawkins, Karl; Maffeis, Thierry G G; Wright, Chris J

2017-01-01

We demonstrate a facile, one-step process to form polymer scaffolds composed of magnetic iron oxide nanoparticles (MNPs) contained within electrospun nano- and micro-fibres of two biocompatible polymers, Poly(ethylene oxide) (PEO) and Poly(vinyl pyrrolidone) (PVP). This was achieved with both needle and free-surface electrospinning systems demonstrating the scalability of the composite fibre manufacture; a 228 fold increase in fibre fabrication was observed for the free-surface system. In all cases the nanoparticle-nanofibre composite scaffolds displayed morphological properties as good as or better than those previously described and fabricated using complex multi-stage techniques. Fibres produced had an average diameter (Needle-spun: 125±18nm (PEO) and 1.58±0.28μm (PVP); Free-surface electrospun: 155±31nm (PEO)) similar to that reported previously, were smooth with no bead defects. Nanoparticle-nanofibre composites were characterised using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), dynamic light scattering (DLS) (Nanoparticle average diameter ranging from 8±3nm to 27±5nm), XRD (Phase of iron oxide nanoparticles identified as magnetite) and nuclear magnetic resonance relaxation measurements (NMR) (T1/T2: 32.44 for PEO fibres containing MNPs) were used to verify the magnetic behaviour of MNPs. This study represents a significant step forward for production rates of magnetic nanoparticle-nanofibre composite scaffolds by the electrospinning technique. Copyright © 2016 Elsevier B.V. All rights reserved.

Composition distributions in FePt(Au) nanoparticles

NASA Astrophysics Data System (ADS)

Srivastava, C.; Nikles, D. E.; Harrell, J. W.; Thompson, G. B.

2010-08-01

Ternary alloy FePt(Au) nanoparticles were prepared by the co-reduction of platinum(II) acetylacetonate and gold(III) acetate and the thermal decomposition of iron pentacarbonyl in hot phenyl ether in the presence of oleic acid and oleylamine ligands. This gave spherical particles with an average diameter of 4.4 nm with a range of diameters from approximately 1.6-9 nm. The as-synthesized particles had a solid solution, face-centered-cubic structure. Though the average composition of the particles was Fe44Pt45Au11, individual particle analysis by Scanning Transmission Electron Microscopy-X-ray Energy Dispersive Spectroscopy showed a broad distribution in composition. In general, smaller-sized particles tended to have a lower amount of Au as compared to larger-sized particles. As the Au content increased, the ratio of Fe/Pt widened.

Comparison of the magnetic properties of metastable hexagonal close-packed Ni nanoparticles with those of the stable face-centered cubic Ni nanoparticles.

PubMed

Jeon, Yoon Tae; Moon, Je Yong; Lee, Gang Ho; Park, Jeunghee; Chang, Yongmin

2006-01-26

We report the first magnetic study of pure and metastable hexagonal close-packed (hcp) Ni nanoparticles (sample 1). We also produced stable face-centered cubic (fcc) Ni nanoparticles, as mixtures with the hcp Ni nanoparticles (samples 2 and 3). We compared the magnetic properties of the hcp Ni nanoparticles with those of the fcc Ni nanoparticles by observing the evolution of magnetic properties from those of the hcp Ni nanoparticles to those of the fcc Ni nanoparticles as the number of fcc Ni nanoparticles increased from sample 1 to sample 3. The blocking temperature (T(B)) of the hcp Ni nanoparticles is approximately 12 K for particle diameters ranging between 8.5 and 18 nm, whereas those of the fcc Ni nanoparticles are 250 and 270 K for average particle diameters of 18 and 26 nm, respectively. The hcp Ni nanoparticles seem to be antiferromagnetic for T < T(B) and paramagnetic for T > T(B). This is very different from the fcc Ni nanoparticles, which are ferromagnetic for T < T(B) and superparamagnetic for T > T(B). This unusual magnetic state of the metastable hcp Ni nanoparticles is likely related to their increased bond distance (2.665 angstroms), compared to that (2.499 angstroms) of the stable fcc Ni nanoparticles.

Preparation and properties of inhalable nanocomposite particles: effects of the temperature at a spray-dryer inlet upon the properties of particles.

PubMed

Tomoda, Keishiro; Ohkoshi, Takumi; Kawai, Yusaku; Nishiwaki, Motoko; Nakajima, Takehisa; Makino, Kimiko

2008-02-15

To overcome the disadvantages both of microparticles and nanoparticles for inhalation, we have prepared nanocomposite particles as drug carriers targeting lungs. The nanocomposite particles having sizes about 2.5 microm composed of sugar and drug-loaded PLGA nanoparticles can reach deep in the lungs, and they are decomposed into drug-loaded PLGA nanoparticles in the alveoli. Sugar was used as a binder of PLGA nanoparticles to be nanocomposite particles and is soluble in alveolar lining fluid. The primary nanoparticles containing bioactive materials were prepared by using a probe sonicator. And then they were spray dried with carrier materials, such as trehalose and lactose. The effects of inlet temperature of spray dryer were studied between 60 and 120 degrees C and the kind of sugars upon properties of nanocomposite particles. When the inlet temperatures were 80 and 90 degrees C, nanocomposite particles with average diameters of about 2.5 microm are obtained and they are decomposed into primary nanoparticles in water, in both sugars are used as a binder. But, those prepared above 100 degrees C are not decomposed into nanoparticles in water, while the average diameter was almost 2.5 microm. On the other hand, nanocomposite particles prepared at lower inlet temperatures have larger sizes but better redispersion efficiency in water. By the measurements of aerodynamic diameters of the nanocomposite particles prepared with trehalose at 70, 80, and 90 degrees C, it was shown that the particles prepared at 80 degrees C have the highest fine particle fraction (FPF) value and the particles are suitable for pulmonary delivery of bioactive materials deep in the lungs. Meanwhile the case with lactose, the particles prepared at 90 degrees C have near the best FPF value but they have many particles larger than 11 microm.

Turbulent heat transfer and nanofluid flow in a protruded ribbed square passage

NASA Astrophysics Data System (ADS)

Kumar, Sunil; Kothiyal, Alok Darshan; Bisht, Mangal Singh; Kumar, Anil

In this article, turbulent heat transfer of nanofluid flow in square passage with protruded rib shape is numerically and experimentally studied over Reynolds number ranges of 4000-18000. Different nanoparticles (Al2O3, CuO, and ZnO), with different concentration (φ) range of 1-4% and different nanoparticle diameter (dnp) range of 30-45 nm are disperse in water (base fluid). Several parameters such as stream wise distance (Xs /dp) range of 1.4-2.6, span wise distance (Ys /dp) range of 1.4-2.6, ratio of protruded height to print diameter (ep /dp) range of 0.83-1.67 also studied to find the consequence on thermal and hydrodynamic characteristics. Simulations were carried out to obtain heat and fluid flow behaviour of smooth and ribbed square channel using commercial CFD software, ANSYS 15.0 (Fluent). Renormalization k - ε model was employed to assess the influence of protruded ribs on turbulent flow and velocity field. The outcome indicates that Al2O3 nanofluid has the highest value of average Nusselt number as compare to other nanofluids. The average Nusselt number increases as the concentration increases and it decreases as nanoparticle diameter increases. The thermal hydrodynamic performance parameter based on equal pumping power, average Nusselt number and average friction factor were found to be highest for Al2O3, φ = 0.04, dnp = 30 nm, Xs /dp = 1.8, Ys /dp = 1.8 and ep /dp = 1.0 . The numerical data are compared with the corresponding experimental data. Comparison between CFD and experimental analysis results showed that good agreement as the data fell within ±7.0% error band.

Morphology and magnetic flux distribution in superparamagnetic, single-crystalline Fe3O4 nanoparticle rings.

PubMed

Takeno, Yumu; Murakami, Yasukazu; Sato, Takeshi; Tanigaki, Toshiaki; Park, Hyun Soon; Shindo, Daisuke; Ferguson, R Matthew; Krishnan, Kannan M

2014-11-03

This study reports on the correlation between crystal orientation and magnetic flux distribution of Fe 3 O 4 nanoparticles in the form of self-assembled rings. High-resolution transmission electron microscopy demonstrated that the nanoparticles were single-crystalline, highly monodispersed, (25 nm average diameter), and showed no appreciable lattice imperfections such as twins or stacking faults. Electron holography studies of these superparamagnetic nanoparticle rings indicated significant fluctuations in the magnetic flux lines, consistent with variations in the magnetocrystalline anisotropy of the nanoparticles. The observations provide useful information for a deeper understanding of the micromagnetics of ultrasmall nanoparticles, where the magnetic dipolar interaction competes with the magnetic anisotropy.

Mesoporous silica templated zirconia nanoparticles

NASA Astrophysics Data System (ADS)

Ballem, Mohamed A.; Córdoba, José M.; Odén, Magnus

2011-07-01

Nanoparticles of zirconium oxide (ZrO2) were synthesized by infiltration of a zirconia precursor (ZrOCl2·8H2O) into a SBA-15 mesoporous silica mold using a wet-impregnation technique. X-ray diffractometry and high-resolution transmission electron microscopy show formation of stable ZrO2 nanoparticles inside the silica pores after a thermal treatment at 550 °C. Subsequent leaching out of the silica template by NaOH resulted in well-dispersed ZrO2 nanoparticles with an average diameter of 4 nm. The formed single crystal nanoparticles are faceted with 110 surfaces termination suggesting it to be the preferred growth orientation. A growth model of these nanoparticles is also suggested.

Synthesis of ZnO nanoparticles by a green process and the investigation of their physical properties

NASA Astrophysics Data System (ADS)

Nethavhanani, T.; Diallo, A.; Madjoe, R.; Kotsedi, L.; Maaza, M.

2018-05-01

This contribution reports on the synthesis and the physical properties of ZnO nanoparticles prepared using a green chemistry process. Aspalathus Linearis's extract was used as an effective chelating agent. The whole reaction process for the ZnO nanoparticle was conducted at room temperature. The microstructural properties of ZnO was investigated using X-ray diffraction, furthermore Electron Dispersive X-rays Spectroscopy was employed as quantitative elemental analysis. From the Transmission Electron Microscopy results, the ZnO nanoparticles were found to be highly crystalline with an average diameter of 23.7 nm.

Rapid extra-/intracellular biosynthesis of gold nanoparticles by the fungus Penicillium sp.

NASA Astrophysics Data System (ADS)

Du, Liangwei; Xian, Liang; Feng, Jia-Xun

2011-03-01

In this work, the fungus Penicillium was used for rapid extra-/intracellular biosynthesis of gold nanoparticles. AuCl4 - ions reacted with the cell filtrate of Penicillium sp. resulting in extracellular biosynthesis of gold nanoparticles within 1 min. Intracellular biosynthesis of gold nanoparticles was obtained by incubating AuCl4 - solution with fungal biomass for 8 h. The gold nanoparticles were characterized by means of visual observation, UV-Vis absorption spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). The extracellular nanoparticles exhibited maximum absorbance at 545 nm in UV-Vis spectroscopy. The XRD spectrum showed Bragg reflections corresponding to the gold nanocrystals. TEM exhibited the formed spherical gold nanoparticles in the size range from 30 to 50 nm with an average size of 45 nm. SEM and TEM revealed that the intracellular gold nanoparticles were well dispersed on the cell wall and within the cell, and they are mostly spherical in shape with an average diameter of 50 nm. The presence of gold was confirmed by EDX analysis.

Synthesis of SiO2-coated ZnMnFe2O4 nanospheres with improved magnetic properties.

PubMed

Wang, Jun; Zhang, Kai; Zhu, Yuejin

2005-05-01

A core-shell structured composite, SiO2 coated ZnMnFe2O4 spinel ferrite nanoparticles (average diameter of approximately 80 nm), was prepared by hydrolysis of tetraethyl orthosilicate (TEOS) in the presence of ZnMnFe2O4 nanoparticles (average diameter of approximately 10 nm) synthesized by a hydrothermal method. The obtained samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and field emission scanning electron microscopy (FESEM). The magnetic measurements were carried out on a vibrating sample magnetometer (VSM), and the measurement results indicate that the core-shell samples possess better magnetic properties at room temperature, compared with paramagnetic colloids with a magnetic core by a coprecipitation method. These core-shell nanospherical particles with self-assembly under additional magnetic fields could have potential application in biomedical systems.

In-situ deposition of Pd nanoparticles on tubular halloysite template for initiation of metallization.

PubMed

Fu, Yubin; Zhang, Lide; Zheng, Jiyong

2005-04-01

Halloysite template has a tubular microstructure; its wall has a multi-layer aluminosilicate structure. A new catalytic method is adopted here, through the in-situ reduction of Pd ions on the surface of tubular halloysite by methanol to initiate electroless plating; the detailed deposition features of Pd nanoparticles are investigated for the first time. The results indicate that an in-situ reduction and deposition of Pd occurs at room temperature, in which the halloysite template plays an important role. Impurities in halloysite (such as ferric oxide) influence the formation and distribution of the Pd nanoparticles. The Pd nanoparticles are of a non-spherical shape in most cases, which would be caused by the irregular appearance of halloysite. No intercalation of the nanoparticles occurs between the aluminosilicate layers in the halloysite. The diameter of Pd nanoparticles increases with time; the average diameter ranges from 1 nm to 4 nm. Pd nanoparticles on a halloysite template can catalyze electroless deposition of Ni to prepare a novel nano-sized cermet at low cost. This practicable catalytic method could also be used on other clay substrates for the initiation of metallization.

Mass-Mobility Characterization of Flame-made ZrO2 Aerosols: Primary Particle Diameter & Extent of Aggregation

PubMed Central

Eggersdorfer, M.L.; Gröhn, A.J.; Sorensen, C.M.; McMurry, P.H.; Pratsinis, S.E.

2013-01-01

Gas-borne nanoparticles undergoing coagulation and sintering form irregular or fractal-like structures affecting their transport, light scattering, effective surface area and density. Here, zirconia (ZrO2) nanoparticles are generated by scalable spray combustion, and their mobility diameter and mass are obtained nearly in-situ by differential mobility analyzer (DMA) and aerosol particle mass (APM) measurements. Using these data, the density of ZrO2 and a power law between mobility and primary particle diameters, the structure of fractal-like particles is determined (mass-mobility exponent, prefactor and average number and surface area mean diameter of primary particles, dva). The dva determined by DMA-APM measurements and this power law is in good agreement with the dva obtained by ex-situ nitrogen adsorption and microscopic analysis. Using this combination of measurements and above power law, the effect of flame spray process parameters (e.g. precursor solution and oxygen flow rate as well as zirconium concentration) on fractal-like particle structure characteristics is investigated in detail. This reveals that predominantly agglomerates (physically-bonded particles) and aggregates (chemically- or sinter-bonded particles) of nanoparticles are formed at low and high particle concentrations, respectively. PMID:22959835

Preparation and characterization of supported magnetic nanoparticles prepared by reverse micelles

PubMed Central

Han, Luyang; Biskupek, Johannes; Kaiser, Ute; Ziemann, Paul

2010-01-01

Summary Monatomic (Fe, Co) and bimetallic (FePt and CoPt) nanoparticles were prepared by exploiting the self-organization of precursor loaded reverse micelles. Achievements and limitations of the preparation approach are critically discussed. We show that self-assembled metallic nanoparticles can be prepared with diameters d = 2–12 nm and interparticle distances D = 20–140 nm on various substrates. Structural, electronic and magnetic properties of the particle arrays were characterized by several techniques to give a comprehensive view of the high quality of the method. For Co nanoparticles, it is demonstrated that magnetostatic interactions can be neglected for distances which are at least 6 times larger than the particle diameter. Focus is placed on FePt alloy nanoparticles which show a huge magnetic anisotropy in the L10 phase, however, this is still less by a factor of 3–4 when compared to the anisotropy of the bulk counterpart. A similar observation was also found for CoPt nanoparticles (NPs). These results are related to imperfect crystal structures as revealed by HRTEM as well as to compositional distributions of the prepared particles. Interestingly, the results demonstrate that the averaged effective magnetic anisotropy of FePt nanoparticles does not strongly depend on size. Consequently, magnetization stability should scale linearly with the volume of the NPs and give rise to a critical value for stability at ambient temperature. Indeed, for diameters above 6 nm such stability is observed for the current FePt and CoPt NPs. Finally, the long-term conservation of nanoparticles by Au photoseeding is presented. PMID:21977392

Evidence for the formation of SiGe nanoparticles in Ge-implanted Si 3N 4

DOE PAGES

Mirzaei, S.; Kremer, F.; Feng, R.; ...

2017-03-14

SiGe nanoparticles were formed in an amorphous Si 3N 4 matrix by Ge + ion implantation and thermal annealing. The size of the nanoparticles was determined by transmission electron microscopy and their atomic structure by x-ray absorption spectroscopy. Nanoparticles were observed for excess Ge concentrations in the range from 9 to 12 at. % after annealing at temperatures in the range from 700 to 900 °C. The average nanoparticle size increased with excess Ge concentration and annealing temperature and varied from an average diameter of 1.8±0.2 nm for the lowest concentration and annealing temperature to 3.2±0.5 nm for the highestmore » concentration and annealing temperature. Our study demonstrates that the structural properties of embedded SiGe nanoparticles in amorphous Si 3N 4 are sensitive to the implantation and post implantation conditions. Furthermore, we demonstrate that ion implantation is a novel pathway to fabricate and control the SiGe nanoparticle structure and potentially useful for future optoelectronic device applications.« less

Thin chitosan films containing super-paramagnetic nanoparticles with contrasting capability in magnetic resonance imaging.

PubMed

Farjadian, Fatemeh; Moradi, Sahar; Hosseini, Majid

2017-03-01

Magnetic nanoparticles have found application as MRI contrasting agents. Herein, chitosan thin films containing super-paramagnetic iron oxide nanoparticles (SPIONs) are evaluated in magnetic resonance imaging (MRI). To determine their contrasting capability, super-paramagnetic nanoparticles coated with citrate (SPIONs-cit) were synthesized. Then, chitosan thin films with different concentrations of SPIONs-cit were prepared and their MRI data (i.e., r 2 and r 2 *) was evaluated in an aqueous medium. The synthesized SPIONs-cit and chitosan/SPIONs-cit films were characterized by FTIR, EDX, XRD as well as VSM with the morphology evaluated by SEM and AFM. The nanoparticle sizes and distribution confirmed well-defined nanoparticles and thin films formation along with high contrasting capability in MRI. Images revealed well-dispersed uniform nanoparticles, averaging 10 nm in size. SPIONs-cit's hydrodynamic size averaged 23 nm in diameter. The crystallinity obeyed a chitosan and SPIONs pattern. The in vitro cellular assay of thin films with a novel route was performed within Hek293 cell lines showing that thin films can be biocompatible.

Octoxy capped Si nanoparticles synthesized by homogeneous reduction of SiCl4 with crown ether alkalide.

PubMed

Sletnes, M; Maria, J; Grande, T; Lindgren, M; Einarsrud, M-A

2014-02-07

Blue-green luminescent octoxy capped Si nanoparticles were synthesized via homogeneous reduction of SiCl4 with the crown ether alkalide K(+)(15-crown-5)2K(-) in tetrahydrofuran. The Si nanoparticles were characterized with respect to size, crystal structure, morphology, surface termination, optical properties and stability. Si diamond structure nanoparticles with narrow size distributions, and average diameters ranging from 3 to 7 nm were obtained. A finite-size effect on the lattice dimensions was observed, in the form of an expansion of the [220] lattice planes of smaller Si nanoparticles. The concentration of SiCl4 was found to be the most important parameter governing the particle size and size distribution. The octoxy capped particles were stable under an ambient atmosphere for at least one month, but exposure to water made them prone to oxidation. An average radiative recombination lifetime of 8.8 ns was measured for the blue-green luminescence. The luminescence appears to originate from surface defects, rather than from quantum confinement.

Superparamagnetic Nanoparticles as High Efficiency Magnetic Resonance Imaging T2 Contrast Agent.

PubMed

Sousa, Fernanda; Sanavio, Barbara; Saccani, Alessandra; Tang, Yun; Zucca, Ileana; Carney, Tamara M; Mastropietro, Alfonso; Jacob Silva, Paulo H; Carney, Randy P; Schenk, Kurt; Omrani, Arash O; Huang, Ping; Yang, Lin; Rønnow, Henrik M; Stellacci, Francesco; Krol, Silke

2017-01-18

Nanoparticle-based magnetic resonance imaging T 2 negative agents are of great interest, and much effort is devoted to increasing cell-loading capability while maintaining low cytotoxicity. Herein, two classes of mixed-ligand protected magnetic-responsive, bimetallic gold/iron nanoparticles (Au/Fe NPs) synthesized by a two-step method are presented. Their structure, surface composition, and magnetic properties are characterized. The two classes of sulfonated Au/Fe NPs, with an average diameter of 4 nm, have an average atomic ratio of Au to Fe equal to 7 or 8, which enables the Au/Fe NPs to be superparamagnetic with a blocking temperature of 56 K and 96 K. Furthermore, preliminary cellular studies reveal that both Au/Fe NPs show very limited toxicity. MRI phantom experiments show that r 2 /r 1 ratio of Au/Fe NPs is as high as 670, leading to a 66% reduction in T 2 relaxation time. These nanoparticles provide great versatility and potential for nanoparticle-based diagnostics and therapeutic applications and as imaging contrast agents.

Characterization of engineered nanoparticles in commercially available spray disinfectant products advertised to contain colloidal silver.

PubMed

Rogers, Kim R; Navratilova, Jana; Stefaniak, Aleksandr; Bowers, Lauren; Knepp, Alycia K; Al-Abed, Souhail R; Potter, Phillip; Gitipour, Alireza; Radwan, Islam; Nelson, Clay; Bradham, Karen D

2018-04-01

Given the potential for human exposure to silver nanoparticles from spray disinfectants and dietary supplements, we characterized the silver-containing nanoparticles in 22 commercial products that advertised the use of silver or colloidal silver as the active ingredient. Characterization parameters included: total silver, fractionated silver (particulate and dissolved), primary particle size distribution, hydrodynamic diameter, particle number, and plasmon resonance absorbance. A high degree of variability between claimed and measured values for total silver was observed. Only 7 of the products showed total silver concentrations within 20% of their nominally reported values. In addition, significant variations in the relative percentages of particulate vs. soluble silver were also measured in many of these products reporting to be colloidal. Primary silver particle size distributions by transmission electron microscopy (TEM) showed two populations of particles - smaller particles (<5nm) and larger particles between 20 and 40nm. Hydrodynamic diameter measurements using nanoparticle tracking analysis (NTA) correlated well with TEM analysis for the larger particles. Z-average (Z-Avg) values measured using dynamic light scattering (DLS); however, were typically larger than both NTA or TEM particle diameters. Plasmon resonance absorbance signatures (peak absorbance at around 400nm indicative of metallic silver nanoparticles) were only noted in 4 of the 9 yellow-brown colored suspensions. Although the total silver concentrations were variable among products, ranging from 0.54mg/L to 960mg/L, silver containing nanoparticles were identified in all of the product suspensions by TEM. Published by Elsevier B.V.

TiO{sub 2}/N-graphene nanocomposite via a facile in-situ hydrothermal sol–gel strategy for visible light photodegradation of eosin Y

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

Liu, Yingliang; Pei, Fuyun, E-mail: xusg@zzu.edu.cn; Lu, Ruijuan

2014-12-15

Highlights: • TiO{sub 2}/N-graphene is synthesized via in-situ hydrothermal sol–gel strategy. • TiO{sub 2} nanoparticles are chemically anchored on N-graphene nanosheets. • The band gap of TiO{sub 2}/N-graphene is red-shifted from neat TiO{sub 2} nanoparticles. • 5-NGT nanocomposite has the best visible light photodegradation performance. - Abstract: TiO{sub 2}/N-graphene nanocomposites are synthesized via a facile in-situ hydrothermal sol–gel strategy in order to improve the photocatalytic efficiency for pollutant photodegradation under visible light irradiation. The as-prepared nanocomposites are respectively characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and UV–vis diffuse reflectance spectroscopy. Results indicated that neatmore » TiO{sub 2} nanoparticles have an average diameter about 6.70 nm while TiO{sub 2} nanoparticles in TiO{sub 2}/N-graphene nanocomposites synthesized through in-situ hydrothermal sol–gel strategy bear an average diameter of ∼1 nm and are anchored on N-graphene nanosheets via chemical bonding. Both neat TiO{sub 2} nanoparticles and chemically anchored TiO{sub 2} nanoparticles in TiO{sub 2}/N-graphene nanocomposites take on the crystal type of anatase. The band gap of TiO{sub 2}/N-graphene nanocomposites is red-shifted compared with neat TiO{sub 2} nanoparticles. The evaluation of photodegradation performance under visible light irradiation suggested that the nanocomposite with 5 wt% N-graphene content has the best visible light photodegradation performance.« less

Diameter control of single-walled carbon nanotube forests from 1.3–3.0 nm by arc plasma deposition

PubMed Central

Chen, Guohai; Seki, Yasuaki; Kimura, Hiroe; Sakurai, Shunsuke; Yumura, Motoo; Hata, Kenji; Futaba, Don N.

2014-01-01

We present a method to both precisely and continuously control the average diameter of single-walled carbon nanotubes in a forest ranging from 1.3 to 3.0 nm with ~1 Å resolution. The diameter control of the forest was achieved through tuning of the catalyst state (size, density, and composition) using arc plasma deposition of nanoparticles. This 1.7 nm control range and 1 Å precision exceed the highest reports to date. PMID:24448201

Towards thiol functionalization of vanadium pentoxide nanotubes using gold nanoparticles

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

Lavayen, V.; O'Dwyer, C.; Cardenas, G.

2007-04-12

Template-directed synthesis is a promising route to realize vanadate-based 1-D nanostructures, an example of which is the formation of vanadium pentoxide nanotubes and associated nanostructures. In this work, we report the interchange of long-chained alkyl amines with alkyl thiols. This reaction was followed using gold nanoparticles prepared by the Chemical Liquid Deposition (CLD) method with an average diameter of {approx}0.9nm and a stability of {approx}85 days. V{sub 2}O{sub 5} nanotubes (VOx-NTs) with lengths of {approx}2{mu}m and internal hollow diameters of 20-100nm were synthesized and functionalized in a Au-acetone colloid with a nominal concentration of {approx}4x10{sup -3}mol dm{sup -3}. The interchangemore » reaction with dodecylamine is found only to occur in polar solvents and incorporation of the gold nanoparticles is not observed in the presence of n-decane.« less

Bovine serum albumin nanoparticles as controlled release carrier for local drug delivery to the inner ear

NASA Astrophysics Data System (ADS)

Yu, Zhan; Yu, Min; Zhang, Zhibao; Hong, Ge; Xiong, Qingqing

2014-07-01

Nanoparticles have attracted increasing attention for local drug delivery to the inner ear recently. Bovine serum albumin (BSA) nanoparticles were prepared by desolvation method followed by glutaraldehyde fixation or heat denaturation. The nanoparticles were spherical in shape with an average diameter of 492 nm. The heat-denatured nanoparticles had good cytocompatibility. The nanoparticles could adhere on and penetrate through the round window membrane of guinea pigs. The nanoparticles were analyzed as drug carriers to investigate the loading capacity and release behaviors. Rhodamine B was used as a model drug in this paper. Rhodamine B-loaded nanoparticles showed a controlled release profile and could be deposited on the osseous spiral lamina. We considered that the bovine serum albumin nanoparticles may have potential applications in the field of local drug delivery in the treatment of inner ear disorders.

Magnetic and elastic anisotropy in magnetorheological elastomers using nickel-based nanoparticles and nanochains

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

Landa, Romina A.; Soledad Antonel, Paula; Ruiz, Mariano M.

2013-12-07

Nickel (Ni) based nanoparticles and nanochains were incorporated as fillers in polydimethylsiloxane (PDMS) elastomers and then these mixtures were thermally cured in the presence of a uniform magnetic field. In this way, macroscopically structured-anisotropic PDMS-Ni based magnetorheological composites were obtained with the formation of pseudo-chains-like structures (referred as needles) oriented in the direction of the applied magnetic field when curing. Nanoparticles were synthesized at room temperature, under air ambient atmosphere (open air, atmospheric pressure) and then calcined at 400 °C (in air atmosphere also). The size distribution was obtained by fitting Small Angle X-ray Scattering (SAXS) experiments with a polydisperse hardmore » spheres model and a Schulz-Zimm distribution, obtaining a size distribution centered at (10.0 ± 0.6) nm with polydispersivity given by σ = (8.0 ± 0.2) nm. The SAXS, X-ray powder diffraction, and Transmission Electron Microscope (TEM) experiments are consistent with single crystal nanoparticles of spherical shape (average particle diameter obtained by TEM: (12 ± 1) nm). Nickel-based nanochains (average diameter: 360 nm; average length: 3 μm, obtained by Scanning Electron Microscopy; aspect ratio = length/diameter ∼ 10) were obtained at 85 °C and ambient atmosphere (open air, atmospheric pressure). The magnetic properties of Ni-based nanoparticles and nanochains at room temperature are compared and discussed in terms of surface and size effects. Both Ni-based nanoparticles and nanochains were used as fillers for obtaining the PDMS structured magnetorheological composites, observing the presence of oriented needles. Magnetization curves, ferromagnetic resonance (FMR) spectra, and strain-stress curves of low filler's loading composites (2% w/w of fillers) were determined as functions of the relative orientation with respect to the needles. The results indicate that even at low loadings it is possible to obtain magnetorheological composites with anisotropic properties, with larger anisotropy when using nanochains. For instance, the magnetic remanence, the FMR field, and the elastic response to compression are higher when measured parallel to the needles (about 30% with nanochains as fillers). Analogously, the elastic response is also anisotropic, with larger anisotropy when using nanochains as fillers. Therefore, all experiments performed confirm the high potential of nickel nanochains to induce anisotropic effects in magnetorheological materials.« less

A New Solution Route to Hydrogen Terminated Silicon Nanoparticles: Synthesis, Functionalization, and Water Stability.

PubMed

Zhang, Xiaoming; Neiner, Doinita; Wang, Shizhong; Louie, Angelique Y; Kauzlarich, Susan M

2007-01-24

Hydrogen capped silicon nanoparticles with strong blue photoluminescence were synthesized by the metathesis reaction of sodium silicide, NaSi, with NH 4 Br. The hydrogen capped Si nanoparticles were further terminated with octyl groups and then coated with a polymer to render them water soluble. The nanoparticles were characterized by TEM, FT-IR, UV-VIS absorption, and photoluminescence. The Si nanoparticles were shown to have an average diameter of 3.9 ±1.3 nm and exhibited room-temperature photoluminescence with a peak maximum at 438 nm with a quantum efficiency of 32% in hexane and 18% in water; the emission was stable in ambient air for up to 2 months. These nanoparticles could hold great potential as a non-heavy element containing quantum dot for applications in biology.

A new solution route to hydrogen-terminated silicon nanoparticles: synthesis, functionalization and water stability

NASA Astrophysics Data System (ADS)

Zhang, Xiaoming; Neiner, Doinita; Wang, Shizhong; Louie, Angelique Y.; Kauzlarich, Susan M.

2007-03-01

Hydrogen-capped silicon nanoparticles with strong blue photoluminescence were synthesized by the metathesis reaction of sodium silicide, NaSi, with NH4Br. The hydrogen-capped Si nanoparticles were further terminated with octyl groups and then coated with a polymer to render them water-soluble. The nanoparticles were characterized by TEM, FT-IR, UV-vis absorption and photoluminescence. The Si nanoparticles were shown to have an average diameter of 3.9 ± 1.3 nm and exhibited room temperature photoluminescence with a peak maximum at 438 nm with a quantum efficiency of 32% in hexane and 18% in water; the emission was stable in ambient air for up to 2 months. These nanoparticles could hold great potential as a non-heavy-element-containing quantum dot for applications in biology.

Porous Carbon Nanofibers from Electrospun Biomass Tar/Polyacrylonitrile/Silver Hybrids as Antimicrobial Materials.

PubMed

Song, Kunlin; Wu, Qinglin; Zhang, Zhen; Ren, Suxia; Lei, Tingzhou; Negulescu, Ioan I; Zhang, Quanguo

2015-07-15

A novel route to fabricate low-cost porous carbon nanofibers (CNFs) using biomass tar, polyacrylonitrile (PAN), and silver nanoparticles has been demonstrated through electrospinning and subsequent stabilization and carbonization processes. The continuous electrospun nanofibers had average diameters ranging from 392 to 903 nm. The addition of biomass tar resulted in increased fiber diameters, reduced thermal stabilities, and slowed cyclization reactions of PAN in the as-spun nanofibers. After stabilization and carbonization, the resultant CNFs showed more uniformly sized and reduced average diameters (226-507 nm) compared to as-spun nanofibers. The CNFs exhibited high specific surface area (>400 m(2)/g) and microporosity, attributed to the combined effects of phase separations of the tar and PAN and thermal decompositions of tar components. These pore characteristics increased the exposures and contacts of silver nanoparticles to the bacteria including Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli, leading to excellent antimicrobial performances of as-spun nanofibers and CNFs. A new strategy is thus provided for utilizing biomass tar as a low-cost precursor to prepare functional CNFs and reduce environmental pollutions associated with direct disposal of tar as an industrial waste.

Copper-Based Metal-Organic Framework Nanoparticles with Peroxidase-Like Activity for Sensitive Colorimetric Detection of Staphylococcus aureus.

PubMed

Wang, Shuqin; Deng, Wenfang; Yang, Lu; Tan, Yueming; Xie, Qingji; Yao, Shouzhuo

2017-07-26

Cu-MOF nanoparticles with an average diameter of 550 nm were synthesized from 2-aminoterephthalic acid and Cu(NO 3 ) 2 by a mixed solvothermal method. The Cu-MOF nanoparticles can show peroxidase-like activity that can catalyze 3,3',5,5'-tetramethylbenzidine to produce a yellow chromogenic reaction in the presence of H 2 O 2 . The presence of abundant amine groups on the surfaces of Cu-MOF nanoparticles enables facile modification of Staphylococcus aureus (S. aureus) aptamer on Cu-MOF nanoparticles. By combining Cu-MOF-catalyzed chromogenic reaction with aptamer recognition and magnetic separation, a simple, sensitive, and selective colorimetric method for the detection of S. aureus was developed.

Core-Shell Magnetic Morphology of Structurally Uniform Magnetite Nanoparticles

NASA Astrophysics Data System (ADS)

Krycka, K. L.; Booth, R. A.; Hogg, C. R.; Ijiri, Y.; Borchers, J. A.; Chen, W. C.; Watson, S. M.; Laver, M.; Gentile, T. R.; Dedon, L. R.; Harris, S.; Rhyne, J. J.; Majetich, S. A.

2010-05-01

A new development in small-angle neutron scattering with polarization analysis allows us to directly extract the average spatial distributions of magnetic moments and their correlations with three-dimensional directional sensitivity in any magnetic field. Applied to a collection of spherical magnetite nanoparticles 9.0 nm in diameter, this enhanced method reveals uniformly canted, magnetically active shells in a nominally saturating field of 1.2 T. The shell thickness depends on temperature, and it disappears altogether when the external field is removed, confirming that these canted nanoparticle shells are magnetic, rather than structural, in origin.

Dose-dependent biodistribution of prenatal exposure to rutile-type titanium dioxide nanoparticles on mouse testis

NASA Astrophysics Data System (ADS)

Kubo-Irie, Miyoko; Uchida, Hiroki; Mastuzawa, Shotaro; Yoshida, Yasuko; Shinkai, Yusuke; Suzuki, Kenichiro; Yokota, Satoshi; Oshio, Shigeru; Takeda, Ken

2014-02-01

Titanium dioxide nanoparticles (nano-TiO2), believed to be inert and safe, are used in many products especially rutile-type in cosmetics. Detection, localization, and count of nanoparticles in tissue sections are of considerable current interest. Here, we evaluate the dose-dependent biodistribution of rutile-type nano-TiO2 exposure during pregnancy on offspring testes. Pregnant mice were subcutaneously injected five times with 0.1 ml of sequentially diluted of nano-TiO2 powder, 35 nm with primary diameter, suspensions (1, 10, 100, or 1,000 μg/ml), and received total doses of 0.5, 5, 50, and 500 μg, respectively. Prior to injection, the size distribution of nano-TiO2 was analyzed by dynamic light scattering measurement. The average diameter was increased in a dose-dependent manner. The most diluted concentration, 1 μg/ml suspension, contained small agglomerates averaging 193.3 ± 5.4 nm in diameter. The offspring testes were examined at 12 weeks postpartum. Individual particle analysis in testicular sections under scanning and transmission electron microscopy enabled us to understand the biodistribution. The correlation between nano-TiO2 doses injected to pregnant mice, and the number of agglomerates in the offspring testes was demonstrated to be dose-dependent by semiquantitative evaluation. However, the agglomerate size was below 200 nm in the testicular sections of all recipient groups, independent from the injected dose during pregnancy.

Effects on diameter and morphology of polycaprolactone nanofibers infused with various concentrations of selenium nanoparticles

NASA Astrophysics Data System (ADS)

Kamaruzaman, Nurul Asyikin; Yusoff, Abdull Rahim Mohd; Buang, Nor Aziah; Salleh, Nik Ghazali Nik

2017-12-01

Electrospinning is one of the techniques used in the fabrication of nanofibers. Polycaprolactone (PCL), is a biodegradable polymer which was commonly electrospun without the presence of nanoparticles as additives and/or filler in the applications such as tissue engineering, biosensors, filtration, wound dressings, drug delivery and enzyme immobilization. In this study, via FESEM analyses, the effects on the diameter and morphology of PCL nanofibers was investigated with respect to various concentration of selenium nanoparticles (SeNP). Increasing the concentration of SeNP from 0.2 to 1.0% (w/v) resulted in increased of fiber diameter as well as the density of the nanofiber networking. Consequently, the formation of beads have also increased with the increment of the concentration of SeNP. The images from FESEM micrographs showed the formation of "aligned fibers" with the average size of less than 550 nm. The optimized concentration of SeNP obtained was 0.4 % w/v for the formation of aligned fibers with a uniform diameter in size and the least formation of beads in the matrices. Aligned nanofibers are biocompatible and can be used in tissue engineering and wound dressing applications. Meanwhile, nanofibers with beads are suitable for filtration design in water and gaseous applications.

Hierarchically assembled Au microspheres and sea urchin-like architectures: formation mechanism and SERS study

NASA Astrophysics Data System (ADS)

Wang, Xiansong; Yang, Da-Peng; Huang, Peng; Li, Min; Li, Chao; Chen, Di; Cui, Daxiang

2012-11-01

The hierarchically assembled Au microspheres/sea urchin-like structures have been synthesized in aqueous solution at room temperature with and without proteins (bovine serum albumin, BSA) as mediators. The average diameter of an individual Au microsphere is 300-600 nm, which is composed of some compact nanoparticles with an average diameter of about 15 nm. Meanwhile, the sea urchin-like Au architecture exhibits an average diameter of 600-800 nm, which is made up of some nanopricks with an average length of 100-200 nm. These products are characterized by means of scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electronic microscopy (TEM). It is found that the BSA and ascorbic acid (AA) have great effects on the morphology of the resulting products. Two different growth mechanisms are proposed. The study on surface enhanced Raman scattering (SERS) activities is also carried out between Au microspheres and Au sea urchin-like architectures. It is found that Au urchin-like architectures possess much higher SERS activity than the Au microspheres. Our work may shed light on the design and synthesis of hierarchically self-assembled 3D micro/nano-architectures for SERS, catalysis and biosensors.The hierarchically assembled Au microspheres/sea urchin-like structures have been synthesized in aqueous solution at room temperature with and without proteins (bovine serum albumin, BSA) as mediators. The average diameter of an individual Au microsphere is 300-600 nm, which is composed of some compact nanoparticles with an average diameter of about 15 nm. Meanwhile, the sea urchin-like Au architecture exhibits an average diameter of 600-800 nm, which is made up of some nanopricks with an average length of 100-200 nm. These products are characterized by means of scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electronic microscopy (TEM). It is found that the BSA and ascorbic acid (AA) have great effects on the morphology of the resulting products. Two different growth mechanisms are proposed. The study on surface enhanced Raman scattering (SERS) activities is also carried out between Au microspheres and Au sea urchin-like architectures. It is found that Au urchin-like architectures possess much higher SERS activity than the Au microspheres. Our work may shed light on the design and synthesis of hierarchically self-assembled 3D micro/nano-architectures for SERS, catalysis and biosensors. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr32405a

Effective heating of magnetic nanoparticle aggregates for in vivo nano-theranostic hyperthermia.

PubMed

Wang, Chencai; Hsu, Chao-Hsiung; Li, Zhao; Hwang, Lian-Pin; Lin, Ying-Chih; Chou, Pi-Tai; Lin, Yung-Ya

2017-01-01

Magnetic resonance (MR) nano-theranostic hyperthermia uses magnetic nanoparticles to target and accumulate at the lesions and generate heat to kill lesion cells directly through hyperthermia or indirectly through thermal activation and control releasing of drugs. Preclinical and translational applications of MR nano-theranostic hyperthermia are currently limited by a few major theoretical difficulties and experimental challenges in in vivo conditions. For example, conventional models for estimating the heat generated and the optimal magnetic nanoparticle sizes for hyperthermia do not accurately reproduce reported in vivo experimental results. In this work, a revised cluster-based model was proposed to predict the specific loss power (SLP) by explicitly considering magnetic nanoparticle aggregation in in vivo conditions. By comparing with the reported experimental results of magnetite Fe 3 O 4 and cobalt ferrite CoFe 2 O 4 magnetic nanoparticles, it is shown that the revised cluster-based model provides a more accurate prediction of the experimental values than the conventional models that assume magnetic nanoparticles act as single units. It also provides a clear physical picture: the aggregation of magnetic nanoparticles increases the cluster magnetic anisotropy while reducing both the cluster domain magnetization and the average magnetic moment, which, in turn, shift the predicted SLP toward a smaller magnetic nanoparticle diameter with lower peak values. As a result, the heating efficiency and the SLP values are decreased. The improvement in the prediction accuracy in in vivo conditions is particularly pronounced when the magnetic nanoparticle diameter is in the range of ~10-20 nm. This happens to be an important size range for MR cancer nano-theranostics, as it exhibits the highest efficacy against both primary and metastatic tumors in vivo. Our studies show that a relatively 20%-25% smaller magnetic nanoparticle diameter should be chosen to reach the maximal heating efficiency in comparison with the optimal size predicted by previous models.

Effective heating of magnetic nanoparticle aggregates for in vivo nano-theranostic hyperthermia

PubMed Central

Wang, Chencai; Hsu, Chao-Hsiung; Li, Zhao; Hwang, Lian-Pin; Lin, Ying-Chih; Chou, Pi-Tai; Lin, Yung-Ya

2017-01-01

Magnetic resonance (MR) nano-theranostic hyperthermia uses magnetic nanoparticles to target and accumulate at the lesions and generate heat to kill lesion cells directly through hyperthermia or indirectly through thermal activation and control releasing of drugs. Preclinical and translational applications of MR nano-theranostic hyperthermia are currently limited by a few major theoretical difficulties and experimental challenges in in vivo conditions. For example, conventional models for estimating the heat generated and the optimal magnetic nanoparticle sizes for hyperthermia do not accurately reproduce reported in vivo experimental results. In this work, a revised cluster-based model was proposed to predict the specific loss power (SLP) by explicitly considering magnetic nanoparticle aggregation in in vivo conditions. By comparing with the reported experimental results of magnetite Fe3O4 and cobalt ferrite CoFe2O4 magnetic nanoparticles, it is shown that the revised cluster-based model provides a more accurate prediction of the experimental values than the conventional models that assume magnetic nanoparticles act as single units. It also provides a clear physical picture: the aggregation of magnetic nanoparticles increases the cluster magnetic anisotropy while reducing both the cluster domain magnetization and the average magnetic moment, which, in turn, shift the predicted SLP toward a smaller magnetic nanoparticle diameter with lower peak values. As a result, the heating efficiency and the SLP values are decreased. The improvement in the prediction accuracy in in vivo conditions is particularly pronounced when the magnetic nanoparticle diameter is in the range of ~10–20 nm. This happens to be an important size range for MR cancer nano-theranostics, as it exhibits the highest efficacy against both primary and metastatic tumors in vivo. Our studies show that a relatively 20%–25% smaller magnetic nanoparticle diameter should be chosen to reach the maximal heating efficiency in comparison with the optimal size predicted by previous models. PMID:28894366

A New Solution Route to Hydrogen Terminated Silicon Nanoparticles: Synthesis, Functionalization, and Water Stability

PubMed Central

Zhang, Xiaoming; Neiner, Doinita; Wang, Shizhong; Louie, Angelique Y.; Kauzlarich, Susan M.

2010-01-01

Hydrogen capped silicon nanoparticles with strong blue photoluminescence were synthesized by the metathesis reaction of sodium silicide, NaSi, with NH4Br. The hydrogen capped Si nanoparticles were further terminated with octyl groups and then coated with a polymer to render them water soluble. The nanoparticles were characterized by TEM, FT-IR, UV-VIS absorption, and photoluminescence. The Si nanoparticles were shown to have an average diameter of 3.9 ±1.3 nm and exhibited room-temperature photoluminescence with a peak maximum at 438 nm with a quantum efficiency of 32% in hexane and 18% in water; the emission was stable in ambient air for up to 2 months. These nanoparticles could hold great potential as a non-heavy element containing quantum dot for applications in biology. PMID:25170189

Phyto-mediated metallic nano-architectures via Melissa officinalis L.: synthesis, characterization and biological properties.

PubMed

Fierascu, Irina; Georgiev, Milen I; Ortan, Alina; Fierascu, Radu Claudiu; Avramescu, Sorin Marius; Ionescu, Daniela; Sutan, Anca; Brinzan, Alexandru; Ditu, Lia Mara

2017-09-29

The development of methods for obtaining new materials with antimicrobial properties, based on green chemistry principles has been a target of research over the past few years. The present paper describes the phyto-mediated synthesis of metallic nano-architectures (gold and silver) via an ethanolic extract of Melissa officinalis L. (obtained by accelerated solvent extraction). Different analytic methods were applied for the evaluation of the extract composition, as well as for the characterization of the phyto-synthesized materials. The cytogenotoxicity of the synthesized materials was evaluated by Allium cepa assay, while the antimicrobial activity was examined by applying both qualitative and quantitative methods. The results demonstrate the synthesis of silver nanoparticles (average diameter 13 nm) and gold nanoparticles (diameter of ca. 10 nm); the bi-metallic nanoparticles proved to have a core-shell flower-like structure, composed of smaller particles (ca. 8 nm). The Ag nanoparticles were found not active on nuclear DNA damage. The Au nanoparticles appeared nucleoprotective, but were aggressive in generating clastogenic aberrations in A. cepa root meristematic cells. Results of the antimicrobial assays show that silver nanoparticles were active against most of the tested strains, as the lowest MIC value being obtained against B. cereus (approx. 0.0015 mM).

Magnetism and Mössbauer study of formation of multi-core γ -Fe2O3 nanoparticles

NASA Astrophysics Data System (ADS)

Kamali, Saeed; Bringas, Eugenio; Hah, Hien-Yoong; Bates, Brian; Johnson, Jacqueline A.; Johnson, Charles E.; Stroeve, Pieter

2018-04-01

A systematic investigation of magnetic nanoparticles and the formation of a core-shell structure, consisting of multiple maghemite (γ -Fe2O3) nanoparticles as the core and silica as the shell, has been performed using various techniques. High-resolution transmission electron microscopy clearly shows isolated maghemite nanoparticles with an average diameter of 13 nm and the formation of a core-shell structure. Low temperature Mössbauer spectroscopy reveals the presence of pure maghemite nanoparticles with all vacancies at the B-sites. Isothermal magnetization and zero-field-cooled and field-cooled measurements are used for investigating the magnetic properties of the nanoparticles. The magnetization results are in good accordance with the contents of the magnetic core and the non-magnetic shell. The multiple-core γ -Fe2O3 nanoparticles show similar behavior to isolated particles of the same size.

Synthesis of Metal Nanoparticle-decorated Carbon Nanotubes under Ambient Conditions

NASA Technical Reports Server (NTRS)

Lin, Yi; Watson, Kent A.; Ghose, Sayata; Smith, Joseph G.; Connell, John W.

2008-01-01

This viewgraph presentation reviews the production of Metal Nanoparticle-decorated carbon Nanotubes. Multi-walled carbon nanotubes (MWCNTs) were efficiently decorated with metal nanoparticles (e.g. Ag, Pt, etc.) using the corresponding metal acetate in a simple mixing process without the need of chemical reagents or further processing. The conversion of acetate compounds to the corresponding metal reached over 90%, forming nanoparticles with average diameters less than 10 nm under certain conditions. The process was readily scalable allowing for the convenient preparation of multi-gram quantities of metal nanoparticle-decorated MWCNTs in a matter of a few minutes. These materials are under evaluation for a variety of electrical and catalytic applications. The preparation and characterization of these materials will be presented. The microscopic views of the processed MWCNTs are shown

Hydrothermal synthesis of histidine-functionalized single-crystalline gold nanoparticles and their pH-dependent UV absorption characteristic.

PubMed

Liu, Zhiguo; Zu, Yuangang; Fu, Yujie; Meng, Ronghua; Guo, Songling; Xing, Zhimin; Tan, Shengnan

2010-03-01

L-Histidine capped single-crystalline gold nanoparticles have been synthesized by a hydrothermal process under a basic condition at temperature between 65 and 150 degrees C. The produced gold nanoparticles were spherical with average diameter of 11.5+/-2.9nm. The synthesized gold colloidal solution was very stable and can be stored at room temperature for more than 6 months. The color of the colloidal solution can change from wine red to mauve, purple and blue during the acidifying process. This color changing phenomenon is attributed to the aggregation of gold nanoparticles resulted from hydrogen bond formation between the histidines adsorbed on the gold nanoparticles surfaces. This hydrothermal synthetic method is expected to be used for synthesizing some other amino acid functionalized gold nanomaterials.

Microwave hydrothermal synthesis and characterization of rare-earth stannate nanoparticles

NASA Astrophysics Data System (ADS)

Huang, Shuang; Xu, Hua-lan; Zhong, Sheng-liang; Wang, Lei

2017-07-01

Rare-earth stannate (Ln2Sn2O7 (Ln = Y, La-Lu)) nanocrystals with an average diameter of 50 nm were prepared through a facile microwave hydrothermal method at 200°C within 60 min. The products were well characterized. The effect of reaction parameters such as temperature, reaction time, pH value, and alkali source on the preparation was investigated. The results revealed that the pH value plays an important role in the formation process of gadolinium stannate (Gd2Sn2O7) nanoparticles. By contrast, the alkali source had no effect on the phase composition or morphology of the final product. Uniform and sphere-like nanoparticles with an average size of approximately 50 nm were obtained at the pH value of 11.5. A possible formation mechanism was briefly proposed. Gd2Sn2O7:Eu3+ nanoparticles displayed strong orange-red emission. Magnetic measurements revealed that Gd2Sn2O7 nanoparticles were paramagnetic. The other rare-earth stannate Ln2Sn2O7 (Ln = Y, La-Lu) nanocrystals were prepared by similar approaches.

Techniques for Accurate Sizing of Gold Nanoparticles Using Dynamic Light Scattering with Particular Application to Chemical and Biological Sensing Based on Aggregate Formation.

PubMed

Zheng, Tianyu; Bott, Steven; Huo, Qun

2016-08-24

Gold nanoparticles (AuNPs) have found broad applications in chemical and biological sensing, catalysis, biomolecular imaging, in vitro diagnostics, cancer therapy, and many other areas. Dynamic light scattering (DLS) is an analytical tool used routinely for nanoparticle size measurement and analysis. Due to its relatively low cost and ease of operation in comparison to other more sophisticated techniques, DLS is the primary choice of instrumentation for analyzing the size and size distribution of nanoparticle suspensions. However, many DLS users are unfamiliar with the principles behind the DLS measurement and are unware of some of the intrinsic limitations as well as the unique capabilities of this technique. The lack of sufficient understanding of DLS often leads to inappropriate experimental design and misinterpretation of the data. In this study, we performed DLS analyses on a series of citrate-stabilized AuNPs with diameters ranging from 10 to 100 nm. Our study shows that the measured hydrodynamic diameters of the AuNPs can vary significantly with concentration and incident laser power. The scattered light intensity of the AuNPs has a nearly sixth order power law increase with diameter, and the enormous scattered light intensity of AuNPs with diameters around or exceeding 80 nm causes a substantial multiple scattering effect in conventional DLS instruments. The effect leads to significant errors in the reported average hydrodynamic diameter of the AuNPs when the measurements are analyzed in the conventional way, without accounting for the multiple scattering. We present here some useful methods to obtain the accurate hydrodynamic size of the AuNPs using DLS. We also demonstrate and explain an extremely powerful aspect of DLS-its exceptional sensitivity in detecting gold nanoparticle aggregate formation, and the use of this unique capability for chemical and biological sensing applications.

Fabrication of Meso-Porous Sintered Metal Thin Films by Selective Etching of Silica Based Sacrificial Template

PubMed Central

Dumée, Ludovic F.; She, Fenghua; Duke, Mikel; Gray, Stephen; Hodgson, Peter; Kong, Lingxue

2014-01-01

Meso-porous metal materials have enhanced surface energies offering unique surface properties with potential applications in chemical catalysis, molecular sensing and selective separation. In this paper, commercial 20 nm diameter metal nano-particles, including silver and copper were blended with 7 nm silica nano-particles by shear mixing. The resulted powders were cold-sintered to form dense, hybrid thin films. The sacrificial silica template was then removed by selective etching in 12 wt% hydrofluoric acid solutions for 15 min to reveal a purely metallic meso-porous thin film material. The impact of the initial silica nano-particle diameter (7–20 nm) as well as the sintering pressure (5–20 ton·m−2) and etching conditions on the morphology and properties of the final nano-porous thin films were investigated by porometry, pyknometery, gas and liquid permeation and electron microscopy. Furthermore, the morphology of the pores and particle aggregation during shear mixing were assessed through cross-sectioning by focus ion beam milling. It is demonstrated that meso-pores ranging between 50 and 320 nm in average diameter and porosities up to 47% can be successfully formed for the range of materials tested. PMID:28344241

Green synthesis of Fe3O4 nanoparticles using aqueous extracts of Pandanus odoratissimus leaves for efficient bifunctional electro-catalytic activity

NASA Astrophysics Data System (ADS)

Alajmi, Mohamed F.; Ahmed, Jahangeer; Hussain, Afzal; Ahamad, Tansir; Alhokbany, Norah; Amir, Samira; Ahmad, Tokeer; Alshehri, Saad M.

2018-04-01

Iron oxide (Fe3O4) nanoparticles (NPs) were prepared at room temperature by one-step synthesis via green chemistry using aqueous extracts of Pandanus odoratissimus leaves. Fe3O4 NPs show uniform particle size distribution with an average diameter of 5.0 nm. BET surface area and average pore diameter of the nanoparticles were found to be 150 m2/g and 3.0 nm, respectively. FTIR, Raman, EDAX and XPS studies were also carried out to confirm the phase purity of the prepared materials. Electrochemical water splitting reactions have been carried out using Fe3O4 NPs as electrocatalysts in 0.1 M KOH electrolyte solution. Polarization studies confirm dual nature of Fe3O4 electro-catalysts in water electrolysis for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Potentiodynamic polarization curves reveal low Tafel values of 295 and 126 mV/dec (± 2) for OER and ORR, respectively. The overpotential for water oxidation reaction was found to be 390 mV (± 5) at the current density of 1 mA/cm2 in 0.1 M KOH. Chronoamperometry and chronopotentiometry experiments were conducted for stability tests of the electrodes.

Role of hydrothermal temperature on crystallinity, photoluminescence, photocatalytic and gas sensing properties of TiO2 nanoparticles

NASA Astrophysics Data System (ADS)

Malligavathy, M.; Iyyapushpam, S.; Nishanthi, S. T.; Padiyan, D. Pathinettam

2018-04-01

TiO2 nanoparticles were synthesised by hydrothermal method. The degree of crystallinity and phase purity were confirmed from the Raman spectra and X-ray diffraction. By increasing the hydrothermal temperature, crystallinity and AC conductivity of the TiO2 nanoparticles increase. Nitrogen adsorption-desorption measurements confirmed that the samples were mesoporous with an average pore diameter of 4.4-7.45 nm. Photocatalytic activity of TiO2 nanoparticles was evaluated and the sample hydrothermally treated at 160°C has the highest photocatalytic activity. In gas sensing measurements, sensitivity increases as a function of concentration and the response to ethanol vapour was better compared to other gases for the sample synthesised at 160°C.

Oral Delivery of DMAB-Modified Docetaxel-Loaded PLGA-TPGS Nanoparticles for Cancer Chemotherapy

NASA Astrophysics Data System (ADS)

Chen, Hongbo; Zheng, Yi; Tian, Ge; Tian, Yan; Zeng, Xiaowei; Liu, Gan; Liu, Kexin; Li, Lei; Li, Zhen; Mei, Lin; Huang, Laiqiang

2011-12-01

Three types of nanoparticle formulation from biodegradable PLGA-TPGS random copolymer were developed in this research for oral administration of anticancer drugs, which include DMAB-modified PLGA nanoparticles, unmodified PLGA-TPGS nanoparticles and DMAB-modified PLGA-TPGS nanoparticles. Firstly, the PLGA-TPGS random copolymer was synthesized and characterized. DMAB was used to increase retention time at the cell surface, thus increasing the chances of particle uptake and improving oral drug bioavailability. Nanoparticles were found to be of spherical shape with an average particle diameter of around 250 nm. The surface charge of PLGA-TPGS nanoparticles was changed to positive after DMAB modification. The results also showed that the DMAB-modified PLGA-TPGS nanoparticles have significantly higher level of the cellular uptake than that of DMAB-modified PLGA nanoparticles and unmodified PLGA-TPGS nanoparticles. In vitro, cytotoxicity experiment showed advantages of the DMAB-modified PLGA-TPGS nanoparticle formulation over commercial Taxotere® in terms of cytotoxicity against MCF-7 cells. In conclusion, oral chemotherapy by DMAB-modified PLGA-TPGS nanoparticle formulation is an attractive and promising treatment option for patients.

A new method for encapsulating hydrophobic compounds within cationic polymeric nanoparticles.

PubMed

Ben Yehuda Greenwald, Maya; Ben Sasson, Shmuel; Bianco-Peled, Havazelet

2013-01-01

Here we present the newly developed "solvent exchange" method that overcomes the challenge of encapsulating hydrophobic compounds within nanoparticle of water soluble polymers. Our studies involved the model polymer polyvinylpyrrolidone (PVP) and the hydrophobic dye Nile red. We found that the minimum molecular weight of the polymer required for nanoparticle formation was 49 KDa. Dynamic Light Scattering (DLS) and Cryo-Transmission Electron Microscopy (cryo-TEM) studies revealed spherical nanoparticles with an average diameter ranging from 20 to 33 nm. Encapsulation efficiency was evaluated using UV spectroscopy and found to be around 94%. The nanocarriers were found to be highly stable; less than 2% of Nile red release from nanoparticles after the addition of NaCl. Nanoparticles containing Nile red were able to penetrate into glioma cells. The solvent exchange method was proved to be applicable for other model hydrophobic drug molecules including ketoprofen, ibuprofen and indomethacin, as well as other solvents.

Stem cell-extracellular vesicles as drug delivery systems: New frontiers for silk/curcumin nanoparticles.

PubMed

Perteghella, Sara; Crivelli, Barbara; Catenacci, Laura; Sorrenti, Milena; Bruni, Giovanna; Necchi, Vittorio; Vigani, Barbara; Sorlini, Marzio; Torre, Maria Luisa; Chlapanidas, Theodora

2017-03-30

The aim of this work was to develop a novel carrier-in-carrier system based on stem cell-extracellular vesicles loaded of silk/curcumin nanoparticles by endogenous technique. Silk nanoparticles were produced by desolvation method and curcumin has been selected as drug model because of its limited water solubility and poor bioavailability. Nanoparticles were stable, with spherical geometry, 100nm in average diameter and the drug content reached about 30%. Cellular uptake studies, performed on mesenchymal stem cells (MSCs), showed the accumulation of nanoparticles in the cytosol around the nuclear membrane, without cytotoxic effects. Finally, MSCs were able to release extracellular vesicles entrapping silk/curcumin nanoparticles. This combined biological-technological approach represents a novel class of nanosystems, combining beneficial effects of both regenerative cell therapies and pharmaceutical nanomedicine, avoiding the use of viable replicating stem cells. Copyright © 2017 Elsevier B.V. All rights reserved.

Palladium nanoparticles deposited on silanized halloysite nanotubes: synthesis, characterization and enhanced catalytic property

NASA Astrophysics Data System (ADS)

Zhang, Yi; He, Xi; Ouyang, Jing; Yang, Huaming

2013-10-01

Palladium (Pd) nanoparticles were deposited on the surface of halloysite nanotubes (HNTs) modified with γ-aminopropyltriethoxysilane (APTES) to produce Pd/NH2-HNTs nanocomposites. The results indicated that Pd nanoparticles were densely immobilized onto NH2-HNTs with an average diameter of ~ 3 nm. The Pd distribution on the surface of silanized HNTs showed much more uniform, and the Pd nanoparticle size became smaller compared with those directly deposited onto HNTs without silanization. Systematic characterization demonstrated that APTES were chemically bonded onto HNTs, and further confirmed the bond formation between Pd and -NH2 groups, which could ensure the firm deposit of Pd nanoparticles on the surface of silanized HNTs. The as-synthesized Pd/NH2-HNTs exhibited an excellent catalytic activity in the liquid-phase hydrogenation of styrene to ethylbenzene with full conversion within 30 min. The mechanism of the deposit of Pd nanoparticles on silanized HNTs was also investigated.

Sensitizing of pyrene fluorescence by β-cyclodextrin-modified TiO2 nanoparticles.

PubMed

Shown, Indrajit; Ujihara, Masaki; Imae, Toyoko

2010-12-15

TiO(2) nanoparticles were synthesized by hydrolysis of tetraisopropyl orthotitanate in an aqueous solution of cyclodextrin. The β-cyclodextrin-modified spherical TiO(2) nanoparticles were water-dispersible and had an average particle diameter of 4.4 ± 1 nm. Pyrene fluorescence was enhanced by increasing the concentration of β-cyclodextrin-modified TiO(2) nanoparticle and the sensitization effect was triply stronger than the case of the β-cyclodextrin only. The increase in a concentration of host (β-cyclodextrin) changes its microenvironment for guest (pyrene), that is, the interaction of pyrene with apolar cavity of β-cyclodextrin increases, resulting in enhancement of fluorescence. The sensitization behavior of pyrene fluorescence in the presence of TiO(2) nanoparticles occurs from the increase in the extinction coefficient of pyrene, demonstrating the charge transfer between pyrene and metal oxide nanoparticle. Crown Copyright © 2010. Published by Elsevier Inc. All rights reserved.

Magneto-plasmonic Au-Coated Co nanoparticles synthesized via hot-injection method

NASA Astrophysics Data System (ADS)

Souza, João B., Jr.; Varanda, Laudemir C.

2018-02-01

A synthetic procedure is described for the obtaining of superparamagnetic Co nanoparticles (NPs) via hot-injection method in the presence of sodium borohydride. The Co NPs obtained have an average diameter of 5.3 nm and saturation magnetization of 115 emu g-1. A modified Langevin equation is fitted to the magnetization curves using a log-normal distribution for the particle diameter and an effective field to account for dipolar interactions. The calculated magnetic diameter of the Co NPs is 0.6 nm smaller than TEM-derived values, implying a magnetic dead layer of 0.3 nm. The magnetic core is coated with Au to prevent oxidation, resulting in water-stable magneto-plasmonic Co/Au core/shell NPs with saturation of 71.6 emu g-1. The coating adds a localized surface plasmon resonance property with absorbance in the so-called ‘therapeutic window’ (690-900 nm), suitable for biomedical applications. It is suggested that these multifunctional NPs are distinguished as a potential platform for applied and fundamental research.

Optical Properties of Nano-Spherical Gold Doped Dye Solution Hybrid

NASA Astrophysics Data System (ADS)

Hoa, D. Q.; Lien, N. T. H.; Ha, C. V.; Nhung, T. H.; Long, P.

2011-03-01

Gold nanoparticles with average diameter of 16 nm which are coated with Cetrimonium Bromide (CTAB) by chemical method are dissolved in dye solution at different concentrations. The absorption spectra of the dye mixture appeared almost unchanged at low concentrations of gold nanoparticles (around 1×1014 cm-3) despite its fluorescence intensity increased many-fold. Energy transfer from gold nanoparticles to dye molecules occurs through surface plasmon resonance(SPR). The fluorescence of rhodamine 610 (Rh610) dye molecules co-adsorbed within 16 nm gold nanoparticles assemblies can be useful for enhancing gain in lasing emission. An increase in laser efficiency by a factor of one and half times stronger compared to the single Rh610 dye suggest the potential of using the mixture of rhodamine dye with gold nanoparticles as laser medium in the configuration of quenching distributed feedback dye laser.

Adsorption of Small Cationic Nanoparticles onto Large Anionic Particles from Aqueous Solution: A Model System for Understanding Pigment Dispersion and the Problem of Effective Particle Density.

PubMed

North, S M; Jones, E R; Smith, G N; Mykhaylyk, O O; Annable, T; Armes, S P

2017-02-07

The present study focuses on the use of copolymer nanoparticles as a dispersant for a model pigment (silica). Reversible addition-fragmentation chain transfer (RAFT) alcoholic dispersion polymerization was used to synthesize sterically stabilized diblock copolymer nanoparticles. The steric stabilizer block was poly(2-(dimethylamino)ethyl methacrylate) (PDMA) and the core-forming block was poly(benzyl methacrylate) (PBzMA). The mean degrees of polymerization for the PDMA and PBzMA blocks were 71 and 100, respectively. Transmission electron microscopy (TEM) studies confirmed a near-monodisperse spherical morphology, while dynamic light scattering (DLS) studies indicated an intensity-average diameter of 30 nm. Small-angle X-ray scattering (SAXS) reported a volume-average diameter of 29 ± 0.5 nm and a mean aggregation number of 154. Aqueous electrophoresis measurements confirmed that these PDMA 71 -PBzMA 100 nanoparticles acquired cationic character when transferred from ethanol to water as a result of protonation of the weakly basic PDMA chains. Electrostatic adsorption of these nanoparticles from aqueous solution onto 470 nm silica particles led to either flocculation at submonolayer coverage or steric stabilization at or above monolayer coverage, as judged by DLS. This technique indicated that saturation coverage was achieved on addition of approximately 465 copolymer nanoparticles per silica particle, which corresponds to a fractional surface coverage of around 0.42. These adsorption data were corroborated using thermogravimetry, UV spectroscopy and X-ray photoelectron spectroscopy. TEM studies indicated that the cationic nanoparticles remained intact on the silica surface after electrostatic adsorption, while aqueous electrophoresis confirmed that surface charge reversal occurred below pH 7. The relatively thick layer of adsorbed nanoparticles led to a significant reduction in the effective particle density of the silica particles from 1.99 g cm -3 to approximately 1.74 g cm -3 , as judged by disk centrifuge photosedimentometry (DCP). Combining the DCP and SAXS data suggests that essentially no deformation of the PBzMA cores occurs during nanoparticle adsorption onto the silica particles.

Average and local crystal structures of (Ga 1–xZn x)(N 1–xO x) solid solution nanoparticles

DOE PAGES

Feygenson, Mikhail; Neuefeind, Joerg C.; Tyson, Trevor A.; ...

2015-11-06

We report the comprehensive study of the crystal structure of (Ga 1–xZn x)(N 1–xO x) solid solution nanoparticles by means of neutron and synchrotron x-ray scattering. In our study we used four different types of (Ga 1–xZn x)(N 1–xO x) nanoparticles, with diameters of 10–27 nm and x = 0.075–0.51, which show the narrow energy-band gaps from 2.21 to 2.61 eV. The Rietveld analysis of the neutron diffraction data revealed that the average crystal structure is the hexagonal wurtzite (space group P6 3mc), in agreement with previous reports on similar bulk materials. The pair-distribution function (PDF) analysis of the samemore » data found that the local structure is more disordered than the average one. It is best described by the model with a lower symmetry space group P1, where atoms are quasirandomly distorted from their nominal positions in the hexagonal wurtzite lattice.« less

Facile synthesis of cobalt ferrite nanotubes using bacterial nanocellulose as template.

PubMed

Menchaca-Nal, S; Londoño-Calderón, C L; Cerrutti, P; Foresti, M L; Pampillo, L; Bilovol, V; Candal, R; Martínez-García, R

2016-02-10

A facile method for the preparation of cobalt ferrite nanotubes by use of bacterial cellulose nanoribbons as a template is described. The proposed method relays on a simple coprecipitation operation, which is a technique extensively used for the synthesis of nanoparticles (either isolated or as aggregates) but not for the synthesis of nanotubes. The precursors employed in the synthesis are chlorides, and the procedure is carried out at low temperature (90 °C). By the method proposed a homogeneous distribution of cobalt ferrite nanotubes with an average diameter of 217 nm in the bacterial nanocellulose (BC) aerogel (3%) was obtained. The obtained nanotubes are formed by 26-102 nm cobalt ferrite clusters of cobalt ferrite nanoparticles with diameters in the 9-13 nm interval. The nanoparticles that form the nanotubes showed to have a certain crystalline disorder, which could be attributed in a greater extent to the small crystallite size, and, in a lesser extent, to microstrains existing in the crystalline lattice. The BC-templated-CoFe2O4 nanotubes exhibited magnetic behavior at room temperature. The magnetic properties showed to be influenced by a fraction of nanoparticles in superparamagnetic state. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effect of surface roughness on substrate-tuned gold nanoparticle gap plasmon resonances.

PubMed

Lumdee, Chatdanai; Yun, Binfeng; Kik, Pieter G

2015-03-07

The effect of nanoscale surface roughness on the gap plasmon resonance of gold nanoparticles on thermally evaporated gold films is investigated experimentally and numerically. Single-particle scattering spectra obtained from 80 nm diameter gold particles on a gold film show significant particle-to-particle variation of the peak scattering wavelength of ±28 nm. The experimental results are compared with numerical simulations of gold nanoparticles positioned on representative rough gold surfaces, modeled based on atomic force microscopy measurements. The predicted spectral variation and average resonance wavelength show good agreement with the measured data. The study shows that nanometer scale surface roughness can significantly affect the performance of gap plasmon-based devices.

Dielectrophoretic immobilisation of nanoparticles as isolated singles in regular arrays

NASA Astrophysics Data System (ADS)

Knigge, Xenia; Wenger, Christian; Bier, Frank F.; Hölzel, Ralph

2018-02-01

We demonstrate the immobilisation of polystyrene nanoparticles on vertical nano-electrodes by means of dielectrophoresis. The electrodes have diameters of 500 nm or 50 nm, respectively, and are arranged in arrays of several thousand electrodes, allowing many thousands of experiments in parallel. At a frequency of 15 kHz, which is found favourable for polystyrene, several occupation patterns are observed, and both temporary and permanent immobilisation is achieved. In addition, a histogram method is applied, which allows to determine the number of particles occupying the electrodes. These results are validated with scanning electron microscopy images. Immobilising exactly one particle at each electrode tip is achieved for electrode tip diameters with half the particle size. Extension of this system down to the level of single molecules is envisaged, which will avoid ensemble averaging at still statistically large sample sizes.

Influence of Substrate, Additives, and Pulse Parameters on Electrodeposition of Gold Nanoparticles from Potassium Dicyanoaurate

NASA Astrophysics Data System (ADS)

Vahdatkhah, Parisa; Sadrnezhaad, Sayed Khatiboleslam

2015-12-01

Gold nanoparticles (AuNPs) of less than 50 nm diameter were electrodeposited from cyanide solution by pulsating electric current on modified copper and indium tin oxide (ITO) films coated on glass. Morphology, size, and composition of the deposited AuNPs were studied by X-ray photoelectron spectroscopy, atomic force microscopy, and field emission scanning electron microscopy. Effects of peak current density, pulse frequency, potassium iodide and cysteine on grain size, and morphology of the AuNPs were determined. Experiments showed that cathode current efficiency increases with the pulse frequency and the iodide ion. Size of the AuNPs increased with the current density. The number of nucleation sites was larger on ITO than on Cu layer; while the average diameter of the crystallites on ITO was smaller than on Cu layer.

Facile synthesis of palladium nanoparticle doped polyaniline nanowires in soft templates for catalytic applications

NASA Astrophysics Data System (ADS)

Kshirasagar, Krushna J.; Markad, Uddhav S.; Saha, Abhijit; Sharma, Kiran Kumar K.; Sharma, Geeta K.

2017-02-01

Palladium nanoparticles doped polyaniline (Pd-PANI) nanocomposite (NCs) is synthesized in surfactant based liquid crystalline mesophase by chemical oxidation followed by radiolysis. The confinement of the liquid crystalline mesophase facilitates polymerization of aniline monomers and their 1D growth into polyaniline (PANI) nanowires by using ammonium persulfate. The PANI nanowires have an average diameter of 30-40 nm. The in situ radiolytic reduction of palladium ions ensures uniform size distribution of the palladium (Pd) nanoparticles on the surface of the PANI nanowires. The synthesized Pd-PANI nanocomposites show wire like structures of PANI (diameter ~30-40 nm) on which Pd nanoparticles of the size 10 nm are decorated. The identical average diameter of the PANI nanowires before and post gamma irradiation suggest high stability of the PANI nanowires in liquid crystalline mesophase. Surface characterization of the NCs were carried out using BET and XPS. The catalytic activity of Pd-PANI NCs are investigated in the reduction of methylene blue (MB) and 4-nitro phenol (4-NP) by sodium borohydride (NaBH4). The kinetics of the Pd-PANI NCs catalysed reactions are analysed using the Langmuir-Hinshelwood model. The apparent rate constant (k app) for the MB and 4-NP reduction reactions is 29  ×  10-3 s-1 and 20  ×  10-3 s-1 respectively with an actual Pd catalyst loading of 2.665  ×  10-4 ppm. Further, the recyclability of the Pd-PANI NCs catalyst in both the reduction reactions shows the stability of the catalyst up to four reaction cycles tested in this investigation and the multifunctional nature of the catalyst. The study provides a new approach for the directional synthesis of conducting polymer-metal nanocomposites and their possible application as a nanocatalyst in environmental remediation.

Ag nanoparticles-decorated ZnO nanorod array on a mechanical flexible substrate with enhanced optical and antimicrobial properties

NASA Astrophysics Data System (ADS)

Chen, Yi; Tse, Wai Hei; Chen, Longyan; Zhang, Jin

2015-03-01

Heteronanostructured zinc oxide nanorod (ZnO NR) array are vertically grown on polydimethylsiloxane (PDMS) through a hydrothermal method followed by an in situ deposition of silver nanoparticles (Ag NPs) through a photoreduction process. The Ag-ZnO heterostructured nanorods on PDMS are measured with an average diameter of 160 nm and an average length of 2 μm. ZnO NRs measured by high-resolution transmission electron microscope (HRTEM) shows highly crystalline with a lattice fringe of 0.255 nm, which corresponds to the (0002) planes in ZnO crystal lattice. The average diameter of the Ag NPs in situ deposited on the ZnO NRs is estimated at 22 ± 2 nm. As compared to the bare ZnO NRs, the heterostructured Ag-ZnO nanorod array shows enhanced ultraviolet (UV) absorption at 440 nm, and significant emission in the visible region (λem = 542 nm). In addition, the antimicrobial efficiency of Ag-ZnO heterostructured nanorod array shows obvious improvement as compared to bare ZnO nanorod array. The cytotoxicity of ZnO nanorod array with and without Ag NPs was studied by using 3 T3 mouse fibroblast cell line. No significant toxic effect is imposed on the cells.

Ag nanoparticles-decorated ZnO nanorod array on a mechanical flexible substrate with enhanced optical and antimicrobial properties.

PubMed

Chen, Yi; Tse, Wai Hei; Chen, Longyan; Zhang, Jin

2015-01-01

Heteronanostructured zinc oxide nanorod (ZnO NR) array are vertically grown on polydimethylsiloxane (PDMS) through a hydrothermal method followed by an in situ deposition of silver nanoparticles (Ag NPs) through a photoreduction process. The Ag-ZnO heterostructured nanorods on PDMS are measured with an average diameter of 160 nm and an average length of 2 μm. ZnO NRs measured by high-resolution transmission electron microscope (HRTEM) shows highly crystalline with a lattice fringe of 0.255 nm, which corresponds to the (0002) planes in ZnO crystal lattice. The average diameter of the Ag NPs in situ deposited on the ZnO NRs is estimated at 22 ± 2 nm. As compared to the bare ZnO NRs, the heterostructured Ag-ZnO nanorod array shows enhanced ultraviolet (UV) absorption at 440 nm, and significant emission in the visible region (λem = 542 nm). In addition, the antimicrobial efficiency of Ag-ZnO heterostructured nanorod array shows obvious improvement as compared to bare ZnO nanorod array. The cytotoxicity of ZnO nanorod array with and without Ag NPs was studied by using 3 T3 mouse fibroblast cell line. No significant toxic effect is imposed on the cells.

Gold nano-decorated aligned polyurethane nanofibers for enhancement of neurite outgrowth and elongation.

PubMed

Demir, Ulku Selcen; Shahbazi, Reza; Calamak, Semih; Ozturk, Sukru; Gultekinoglu, Merve; Ulubayram, Kezban

2018-06-01

Neurite outgrowth and elongation of neural cells is the most important subject that is considered in nerve tissue engineering. In this regard, aligned nanofibers have taken much attention in terms of providing guidance for newly outgrown neurites. The main objective of this study was to fabricate aligned polyurethane nanofibers by electrospinning process and decorate them with gold nanoparticles to further investigate the synergistic effects of nanotopography, biological nerve growth factor (NGF) and electrical stimulations on neurite outgrowth and elongation of pheochromocytoma (PC-12) model cells. In this regard, smooth and uniform aligned polyurethane nanofibers with the average diameter of 519 ± 56 nm were fabricated and decorated with the gold nanoparticles with the average diameter of ∼50 nm. PC-12 cells were cultured on the various nanofiber surfaces inside the bio-mimetic bioreactor system and exposed either to NGF alone or combination of NGF and electrical stimulation. It was found that 50 ng/mL NGF concentration is an optimal value for the stimulation of neurite outgrowth. After 4 days of culture under 100 mV, 10 ms electrical stimulation in 1 h/day period it was found that the gold nanoparticle decorated aligned polyurethane nanofibers increased the neurite outgrowth and elongation more with the combinational NGF and electrical stimulation. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1604-1613, 2018. © 2018 Wiley Periodicals, Inc.

Magnetically targeted delivery through cartilage

NASA Astrophysics Data System (ADS)

Jafari, Sahar; Mair, Lamar O.; Chowdhury, Sagar; Nacev, Alek; Hilaman, Ryan; Stepanov, Pavel; Baker-McKee, James; Ijanaten, Said; Koudelka, Christian; English, Bradley; Malik, Pulkit; Weinberg, Irving N.

2018-05-01

In this study, we have invented a method of delivering drugs deep into articular cartilage with shaped dynamic magnetic fields acting on small metallic magnetic nanoparticles with polyethylene glycol coating and average diameter of 30 nm. It was shown that transport of magnetic nanoparticles through the entire thickness of bovine articular cartilage can be controlled by a combined alternating magnetic field at 100 Hz frequency and static magnetic field of 0.8 tesla (T) generated by 1" dia. x 2" thick permanent magnet. Magnetic nanoparticles transport through bovine articular cartilage samples was investigated at various settings of magnetic field and time durations. Combined application of an alternating magnetic field and the static field gradient resulted in a nearly 50 times increase in magnetic nanoparticles transport in bovine articular cartilage tissue as compared with static field conditions. This method can be applied to locally deliver therapeutic-loaded magnetic nanoparticles deep into articular cartilage to prevent cartilage degeneration and promote cartilage repair in osteoarthritis.

Synthesis and characterization of tat-mediated O-CMC magnetic nanoparticles having anticancer function

NASA Astrophysics Data System (ADS)

Zhao, Aijie; Yao, Peng; Kang, Chunshang; Yuan, Xubo; Chang, Jin; Pu, Peiyu

2005-08-01

This paper describes a new formulation of magnetic nanoparticles coated by a novel polymer matrix—O-carboxylmethylated chitosan (O-CMC) as drug/gene carrier. The O-CMC magnetic nanoparticles were derivatized with a peptide sequence from the HIV-tat protein to improve the translocational property and cellar uptake of the nanoparticles. To evaluate the O-MNPs-tat as drug carriers, MTX was incorporated as a model drug and MTX-loaded O-MNPs-tat with an average diameter of 45-60 nm were prepared and characterized by TEM, AFM and VSM. The cytotoxicity of MTX-loaded O-MNPs-tat was investigated with U-937 tumor cells. The results showed that the MTX-loaded O-MNPs-tat retained significant antitumor toxicity; additionally, sustained release of MTX from O-CMC nanoparticles was observed in vitro, suggesting that the tat-O-MNPs could be a novel magnetic targeting carrier.

Sol-Gel assembly of CdSe nanoparticles to form porous aerogel networks.

PubMed

Arachchige, Indika U; Brock, Stephanie L

2006-06-21

A detailed study of CdSe aerogels prepared by oxidative aggregation of primary nanoparticles (prepared at room temperature and high temperature conditions, >250 degrees C), followed by CO2 supercritical drying, is described. The resultant materials are mesoporous, with an interconnected network of colloidal nanoparticles, and exhibit BET surface areas up to 224 m2/g and BJH average pore diameters in the range of 16-32 nm. Powder X-ray diffraction studies indicate that these materials retain the crystal structure of the primary nanoparticles, with a slight increase in primary particle size upon gelation and aerogel formation. Optical band gap measurements and photoluminescence studies show that the as-prepared aerogels retain the quantum-confined optical properties of the nanoparticle building blocks despite being connected into a 3-D network. The specific optical characteristics of the aerogel can be further modified by surface ligand exchange at the wet-gel stage, without destroying the gel network.

Direct observation of metal nanoparticles as heterogeneous nuclei for the condensation of supersaturated organic vapors: nucleation of size-selected aluminum nanoparticles in acetonitrile and n-hexane vapors.

PubMed

Abdelsayed, Victor; El-Shall, M Samy

2014-08-07

This work reports the direct observation and separation of size-selected aluminum nanoparticles acting as heterogeneous nuclei for the condensation of supersaturated vapors of both polar and nonpolar molecules. In the experiment, we study the condensation of supersaturated acetonitrile and n-hexane vapors on charged and neutral Al nanoparticles by activation of the metal nanoparticles to act as heterogeneous nuclei for the condensation of the organic vapor. Aluminum seed nanoparticles with diameters of 1 and 2 nm are capable of acting as heterogeneous nuclei for the condensation of supersaturated acetonitrile and hexane vapors. The comparison between the Kelvin and Fletcher diameters indicates that for the heterogeneous nucleation of both acetonitrile and hexane vapors, particles are activated at significantly smaller sizes than predicted by the Kelvin equation. The activation of the Al nanoparticles occurs at nearly 40% and 65% of the onset of homogeneous nucleation of acetonitrile and hexane supersaturated vapors, respectively. The lower activation of the charged Al nanoparticles in acetonitrile vapor is due to the charge-dipole interaction which results in rapid condensation of the highly polar acetonitrile molecules on the charged Al nanoparticles. The charge-dipole interaction decreases with increasing the size of the Al nanoparticles and therefore at low supersaturations, most of the heterogeneous nucleation events are occurring on neutral nanoparticles. No sign effect has been observed for the condensation of the organic vapors on the positively and negatively charged Al nanoparticles. The present approach of generating metal nanoparticles by pulsed laser vaporization within a supersaturated organic vapor allows for efficient separation between nucleation and growth of the metal nanoparticles and, consequently controls the average particle size, particle density, and particle size distribution within the liquid droplets of the condensing vapor. Strong correlation is found between the seed nanoparticle's size and the degree of the supersaturation of the condensing vapor. This result and the agreement among the calculated Kelvin diameters and the size of the nucleating Al nanoparticles determined by transmission electron microscopy provide strong proof for the development of a new approach for the separation and characterization of heterogeneous nuclei formed in organic vapors. These processes can take place in the atmosphere by a combination of several organic species including polar compounds which could be very efficient in activating charged nanoparticles and cluster ions of atmospheric relevance.

Direct observation of metal nanoparticles as heterogeneous nuclei for the condensation of supersaturated organic vapors: Nucleation of size-selected aluminum nanoparticles in acetonitrile and n-hexane vapors

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

Abdelsayed, Victor; Samy El-Shall, M., E-mail: mselshal@vcu.edu

This work reports the direct observation and separation of size-selected aluminum nanoparticles acting as heterogeneous nuclei for the condensation of supersaturated vapors of both polar and nonpolar molecules. In the experiment, we study the condensation of supersaturated acetonitrile and n-hexane vapors on charged and neutral Al nanoparticles by activation of the metal nanoparticles to act as heterogeneous nuclei for the condensation of the organic vapor. Aluminum seed nanoparticles with diameters of 1 and 2 nm are capable of acting as heterogeneous nuclei for the condensation of supersaturated acetonitrile and hexane vapors. The comparison between the Kelvin and Fletcher diameters indicatesmore » that for the heterogeneous nucleation of both acetonitrile and hexane vapors, particles are activated at significantly smaller sizes than predicted by the Kelvin equation. The activation of the Al nanoparticles occurs at nearly 40% and 65% of the onset of homogeneous nucleation of acetonitrile and hexane supersaturated vapors, respectively. The lower activation of the charged Al nanoparticles in acetonitrile vapor is due to the charge-dipole interaction which results in rapid condensation of the highly polar acetonitrile molecules on the charged Al nanoparticles. The charge-dipole interaction decreases with increasing the size of the Al nanoparticles and therefore at low supersaturations, most of the heterogeneous nucleation events are occurring on neutral nanoparticles. No sign effect has been observed for the condensation of the organic vapors on the positively and negatively charged Al nanoparticles. The present approach of generating metal nanoparticles by pulsed laser vaporization within a supersaturated organic vapor allows for efficient separation between nucleation and growth of the metal nanoparticles and, consequently controls the average particle size, particle density, and particle size distribution within the liquid droplets of the condensing vapor. Strong correlation is found between the seed nanoparticle's size and the degree of the supersaturation of the condensing vapor. This result and the agreement among the calculated Kelvin diameters and the size of the nucleating Al nanoparticles determined by transmission electron microscopy provide strong proof for the development of a new approach for the separation and characterization of heterogeneous nuclei formed in organic vapors. These processes can take place in the atmosphere by a combination of several organic species including polar compounds which could be very efficient in activating charged nanoparticles and cluster ions of atmospheric relevance.« less

A facile construction strategy of stable lipid nanoparticles for drug delivery using a hydrogel-thickened microemulsion system

NASA Astrophysics Data System (ADS)

Chen, Huabing; Xiao, Ling; Du, Danrong; Mou, Dongsheng; Xu, Huibi; Yang, Xiangliang

2010-01-01

We report a novel facile method for preparing stable nanoparticles with inner spherical solid spheres and an outer hydrogel matrix using a hot O/W hydrogel-thickened microemulsion with spontaneous stability. The nanoparticles with average diameters of about 30.0 nm and 100.0 nm were constructed by cooling the hot hydrogel-thickened microemulsion at different temperatures, respectively. We explained the application of these nanoparticles by actualizing the cutaneous delivery of drug-loaded nanoparticles. The in vitro skin permeation studies showed that the nanoparticles could significantly reduce the penetration of model drugs through skin and resulted in their dermal uptakes in skin. The sol-gel process of TEOS was furthermore used in the template of HTM to regulate the particle size of nanoparticles. The coating of silica on the surface of nanoparticles could regulate the penetration of drug into skin from dermal delivery to transdermal delivery. This strategy provides a facile method to produce nanoparticles with long-term stability and ease of manufacture, which might have a promising application in drug delivery.

TOPO-capped silver selenide nanoparticles and their incorporation into polymer nanofibers using electrospinning technique

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

More, D.S.; Moloto, M.J., E-mail: makwenam@vut.ac.za; Moloto, N.

Highlights: • Ag{sub 2}Se nanoparticles produced spherical particles with sizes 12 nm (180 °C) and 27 nm (200 °C). • Higher temperature produced increased particle size (∼75 nm) and changed in shape. • Ag{sub 2}Se nanoparticles (0.2–0.6%) added into PVP (35–45%) to yield reduced fiber beading. • Polymer nanofibers electrospun at 11–20 kV produced fiber diameters of 425–461 nm. • Optical properties in the fibers were observed due to the Ag{sub 2}Se nanoparticles loaded. - Abstract: Electrospinning is the most common technique for fabricating polymer fibers as well as nanoparticles embedded polymer fibers. Silver selenide nanoparticles were synthesized using tri-n-octylphosphinemore » (TOP) as solvent and tri-n-octylphosphine oxide (TOPO) as capping environment. Silver selenide was prepared by reacting silver nitrate and selenium with tri-n-octylphosphine (TOP) to form TOP–Ag and TOP–Se solutions. Both absorption and emission spectra signify the formation of nanoparticles as well as the TEM which revealed spherical particles with an average particle size of 22 nm. The polymer, PVP used was prepared at concentrations ranging from (35 to 45 wt%) and the TOPO-capped silver selenide nanoparticles (0.2 and 0.6 wt%) were incorporated into them and electrospun by varying the voltage from 11 to 20 kV. The SEM images of the Ag{sub 2}Se/PVP composite fibers revealed the fibers of diameters with average values of 425 and 461 nm. The X-ray diffraction results show peaks which were identified due to α-Ag{sub 2}Se body centered cubic compound. The sharp peak observed for all the samples at 2θ = 44.5 suggest the presence of Ag in the face centered cubic which can be attributed to higher concentration of silver nitrate used with molar ratio of selenium to silver and the abundance of silver in the silver selenide crystal. Fourier transform infrared spectroscopy, thermogravimetric analysis (TGA) and ultraviolet–visible spectroscopy were used to characterize the structure of the PVP/Ag{sub 2}Se composite fibers.« less

Application of gallium nitride nanostructures and nitrogen doped carbon spheres as supports for the hydrogenation of cinnamaldehyde.

PubMed

Kente, Thobeka; Dube, Sibongile M A; Coville, Neil J; Mhlanga, Sabelo D

2013-07-01

This paper reports on the synthesis and use of nanostructures of gallium nitride (GaN NSs) and nitrogen doped carbon spheres (NCSs) as support materials for the hydrogenation of cinnamaldehyde. This study provides the first investigation of GaN as a catalyst support in hydrogenation reactions. The GaN NSs were synthesized via chemical vapour deposition (CVD) in a double stage furnace (750 degrees C) while NCSs were made by CVD in a single stage furnace (950 degrees C) respectively. TEM analysis revealed that the GaN NSs were rod-like with average diameters of 200 nm, while the NCSs were solid with smoother surfaces, and with diameters of 450 nm. Pd nanoparticles (1 and 3% loadings) were uniformly dispersed on acid functionalized GaN NSs and NCS. The Pd nanoparticles had average diameters that were influenced by the type of support material used. The GaN NSs and NCSs were tested for the selective hydrogenation of cinnamaldehyde in isopropanol at 40 and 60 degrees C under atmospheric pressure. A comparative study of the activity of the nanostructured materials revealed that the order of catalyst activity was 3% Pd/GaN > 3% Pd/NCSs > 1% Pd/NCSs > 1% Pd/GaN. However, 100% selectivity to hydrocinnamaldehyde (HCALD) was obtained with 1% Pd/GaN at reasonable conversion rates.

Photodegradation of Eosin Y Using Silver-Doped Magnetic Nanoparticles

PubMed Central

Alzahrani, Eman

2015-01-01

The purification of industrial wastewater from dyes is becoming increasingly important since they are toxic or carcinogenic to human beings. Nanomaterials have been receiving significant attention due to their unique physical and chemical properties compared with their larger-size counterparts. The aim of the present investigation was to fabricate magnetic nanoparticles (MNPs) using a coprecipitation method, followed by coating with silver (Ag) in order to enhance the photocatalytic activity of the MNPs by loading metal onto them. The fabricated magnetic nanoparticles coated with Ag were characterised using different instruments such as a scanning electron microscope (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray (EDAX) spectroscopy, and X-ray diffraction (XRD) analysis. The average size of the magnetic nanoparticles had a mean diameter of about 48 nm, and the average particle size changed to 55 nm after doping. The fabricated Ag-doped magnetic nanoparticles were used for the degradation of eosin Y under UV-lamp irradiation. The experimental results revealed that the use of fabricated magnetic nanoparticles coated with Ag can be considered as reliable methods for the removal of eosin Y since the slope of evaluation of pseudo-first-order rate constant from the slope of the plot between ln⁡(C o/C) and the irradiation time was found to be linear. Ag-Fe3O4 nanoparticles would be considered an efficient photocatalyst to degrade textile dyes avoiding the tedious filtration step. PMID:26617638

Hierarchically assembled Au microspheres and sea urchin-like architectures: formation mechanism and SERS study.

PubMed

Wang, Xiansong; Yang, Da-Peng; Huang, Peng; Li, Min; Li, Chao; Chen, Di; Cui, Daxiang

2012-12-21

The hierarchically assembled Au microspheres/sea urchin-like structures have been synthesized in aqueous solution at room temperature with and without proteins (bovine serum albumin, BSA) as mediators. The average diameter of an individual Au microsphere is 300-600 nm, which is composed of some compact nanoparticles with an average diameter of about 15 nm. Meanwhile, the sea urchin-like Au architecture exhibits an average diameter of 600-800 nm, which is made up of some nanopricks with an average length of 100-200 nm. These products are characterized by means of scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electronic microscopy (TEM). It is found that the BSA and ascorbic acid (AA) have great effects on the morphology of the resulting products. Two different growth mechanisms are proposed. The study on surface enhanced Raman scattering (SERS) activities is also carried out between Au microspheres and Au sea urchin-like architectures. It is found that Au urchin-like architectures possess much higher SERS activity than the Au microspheres. Our work may shed light on the design and synthesis of hierarchically self-assembled 3D micro/nano-architectures for SERS, catalysis and biosensors.

Biocellulose-based flexible magnetic paper

NASA Astrophysics Data System (ADS)

Barud, H. S.; Tercjak, A.; Gutierrez, J.; Viali, W. R.; Nunes, E. S.; Ribeiro, S. J. L.; Jafellici, M.; Nalin, M.; Marques, R. F. C.

2015-05-01

Biocellulose or bacterial cellulose (BC) is a biocompatible (nano) material produced with a three-dimensional network structure composed of microfibrils having nanometric diameters obtained by the Gluconacetobacter xylinus bacteria. BC membranes present relatively high porosity, allowing the incorporation or synthesis in situ of inorganic nanoparticles for multifunctional applications and have been used as flexible membranes for incorporation of magnetic nanocomposite. In this work, highly stable superparamagnetic iron oxide nanoparticles (SPION), functionalized with polyethylene glycol (PEG), with an average diameter of 5 nm and a saturation magnetization of 41 emu/g at 300 K were prepared. PEG-Fe2O3 hybrid was dispersed by mixing a pristine BC membrane in a stable aqueous dispersion of PEG-SPION. The PEG chains at PEG-SPION's surface provide a good permeability and strong affinity between the BC chains and SPION through hydrogen-bonding interactions. PEG-SPION also allow the incorporation of higher content of nanoparticles without compromising the mechanical properties of the nanocomposite. Structural and magnetic properties of the composite have been characterized by XRD, SEM, energy-dispersive X-ray spectroscopy (EDX), magnetization, Raman spectroscopy, and magnetic force microscopy.

Numerical simulation of the nanoparticle diameter effect on the thermal performance of a nanofluid in a cooling chamber

NASA Astrophysics Data System (ADS)

Ghafouri, A.; Pourmahmoud, N.; Jozaei, A. F.

2017-03-01

The thermal performance of a nanofluid in a cooling chamber with variations of the nanoparticle diameter is numerically investigated. The chamber is filled with water and nanoparticles of alumina (Al2O3). Appropriate nanofluid models are used to approximate the nanofluid thermal conductivity and dynamic viscosity by incorporating the effects of the nanoparticle concentration, Brownian motion, temperature, nanoparticles diameter, and interfacial layer thickness. The horizontal boundaries of the square domain are assumed to be insulated, and the vertical boundaries are considered to be isothermal. The governing stream-vorticity equations are solved by using a secondorder central finite difference scheme coupled with the mass and energy conservation equations. The results of the present work are found to be in good agreement with the previously published data for special cases. This study is conducted for the Reynolds number being fixed at Re = 100 and different values of the nanoparticle volume fraction, Richardson number, nanofluid temperature, and nanoparticle diameter. The results show that the heat transfer rate and the Nusselt number are enhanced by increasing the nanoparticle volume fraction and decreasing the Richardson number. The Nusselt number also increases as the nanoparticle diameter decreases.

The correlation between gelatin macroscale differences and nanoparticle properties: providing insight into biopolymer variability.

PubMed

Stevenson, André T; Jankus, Danny J; Tarshis, Max A; Whittington, Abby R

2018-05-21

From therapeutic delivery to sustainable packaging, manipulation of biopolymers into nanostructures imparts biocompatibility to numerous materials with minimal environmental pollution during processing. While biopolymers are appealing natural based materials, the lack of nanoparticle (NP) physicochemical consistency has decreased their nanoscale translation into actual products. Insights regarding the macroscale and nanoscale property variation of gelatin, one of the most common biopolymers already utilized in its bulk form, are presented. Novel correlations between macroscale and nanoscale properties were made by characterizing similar gelatin rigidities obtained from different manufacturers. Samples with significant differences in clarity, indicating sample purity, obtained the largest deviations in NP diameter. Furthermore, a statistically significant positive correlation between macroscale molecular weight dispersity and NP diameter was determined. New theoretical calculations proposing the limited number of gelatin chains that can aggregate and subsequently get crosslinked for NP formation were presented as one possible reason to substantiate the correlation analysis. NP charge and crosslinking extent were also related to diameter. Lower gelatin sample molecular weight dispersities produced statistically smaller average diameters (<75 nm), and higher average electrostatic charges (∼30 mV) and crosslinking extents (∼95%), which were independent of gelatin rigidity, conclusions not shown in the literature. This study demonstrates that the molecular weight composition of the starting material is one significant factor affecting gelatin nanoscale properties and must be characterized prior to NP preparation. Identifying gelatin macroscale and nanoscale correlations offers a route toward greater physicochemical property control and reproducibility of new NP formulations for translation to industry.

Enhanced magnetization in VxFe3-xO4 nanoparticles

NASA Astrophysics Data System (ADS)

Pool, V. L.; Kleb, M. T.; Chorney, C. L.; Arenholz, E.; Idzerda, Y. U.

2015-12-01

Nanoparticles of VxFe3-xO4 with up to 33% vanadium doping (x=0 to 1) and a 9 nm diameter are investigated in order to determine the site preference of the vanadium and the magnetic behavior of the nanoparticles. The iron and vanadium L23-edge X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (MCD) spectra are used to identify that vanadium initially substitutes into the tetrahedral iron site as V3+ and that the average iron moment is observed to increase with vanadium concentration up to 12.5% (x=.375). When the vanadium incorporation exceeds 12.5%, the XAS and MCD show that the vanadium begins substituting as V2+ in the octahedral coordination. This coincides with a rapid reduction of the average moment to zero by 25% (x=.75). The frequency-dependent alternating-current magnetic susceptibility (ACMS) displays a substantial increase in blocking temperature with vanadium concentration and indicated substantial variation in the strength of inter-particle interactions.

Facile fabrication of silver nanoparticles with temperature-responsive sizes as highly active SERS substrates

NASA Astrophysics Data System (ADS)

Wu, Jing; Fang, Jinghuai; Cheng, Mingfei; Gong, Xiao

2016-12-01

In our work, large-scale silver NPs (nanoparticles) are successfully synthesized on zinc foils with controllable size by regulating the temperature of the displacement reaction. Our results show that when the temperature is 70 °C, the average size of silver NPs is approximately 88 nm in diameter, and they exhibit the strongest SERS activity. The gap between nanoparticles is simultaneously regulated as near as possible, which produces abundant "hot spots" and nanogaps. Crystal violet (CV) was used as probe molecules, and the SERS signals show that the values of relative standard deviation in the intensity of the main vibration modes are less than 10%, demonstrating excellent reproducibility of the silver NPs. Furthermore, the high surface-average enhancement factor of 3.86 × 107 is achieved even when the concentration of CV is 10-7 M, which is sufficient for single-molecule detection. We believe that this low cost and rapid route would get wide applications in chemical synthesis.

Development of hyaluronic acid-Fe2O3 hybrid magnetic nanoparticles for targeted delivery of peptides.

PubMed

Kumar, Arun; Sahoo, Bishwabhusan; Montpetit, Alison; Behera, Sumita; Lockey, Richard F; Mohapatra, Shyam S

2007-06-01

Novel hybrid nanoparticles comprised of hyaluronic acid (HA) and iron oxide were synthesized and characterized for the first time with the average diameter of less than 160 nm. The iron oxide (Fe2O3) particles are hybridized between HA layers by electrostatic interactions between the positive surface charge of the Fe2O3 nanoparticles and the negative charge of the carboxylate groups of HA, forming a corral-like structure. The particles were also characterized by FTIR and NMR to verify the hybridization. The particles were tested for their ability to deliver peptides to the cells using HEK293 and A549 cells. Results show that these particles delivered peptides at about 100% level. These HA-iron oxide nanoparticles are expected to be useful in developing effective tissue and cell targeting systems.

MnFe2O4 as a gas sensor towards SO2 and NO2 gases

NASA Astrophysics Data System (ADS)

Rathore, Deepshikha; Mitra, Supratim

2016-05-01

The chemical co-precipitation method was used to synthesize MnFe2O4 nanoparticles. Single cubic phase formation of nanoparticles was confirmed by X-ray diffraction technique. The average particle size of MnFe2O4 nanoparticles was found to be 10.7 nm using Scherrer formula. The ultrafine powder of MnFe2O4 nanoparticles was pressed to design pellet of 10 mm diameter and 1mm thickness. Copper electrodes have been deposited on the surface of pellet using silver paste in the form of capacitor. Fabricated gas sensing device of MnFe2O4 nanoparticles was tested towards SO2 and NO2 gases. Cole-Cole plot of MnFe2O4 was investigated with the help of electrochemical workstation. The performance of the sensors including sensitivity, response and recovery time was also determined. It was observed that the MnFe2O4 nanoparticles are more sensible for NO2 gas as compared to SO2 gas.

High efficiency protein separation with organosilane assembled silica coated magnetic nanoparticles

NASA Astrophysics Data System (ADS)

Chang, Jeong Ho; Kang, Ki Ho; Choi, Jinsub; Jeong, Young Keun

2008-10-01

This work describes the development of high efficiency protein separation with functionalized organosilanes on the surface of silica coated magnetic nanoparticles. The magnetic nanoparticles were synthesized with average particle size of 9 nm and silica coated magnetic nanoparticles were obtained by controlling the coating thicknesses on magnetic nanoparticles. The silica coating thickness could be uniformly sized with a diameter of 10-40 nm by a sol-gel approach. The surface modification was performed with four kinds of functionalized organosilanes such as carboxyl, aldehyde, amine, and thiol groups. The protein separation work with organosilane assembled silica coated magnetic nanoparticles was achieved for model proteins such as bovine serum albumin (BSA) and lysozyme (LSZ) at different pH conditions. Among the various functionalities, the thiol group showed good separation efficiency due to the change of electrostatic interactions and protein conformational structure. The adsorption efficiency of BSA and LSZ was up to 74% and 90% corresponding pH 4.65 and pH 11.

Development of Iron Doped Silicon Nanoparticles as Bimodal Imaging Agents

PubMed Central

Singh, Mani P.; Atkins, Tonya M.; Muthuswamy, Elayaraja; Kamali, Saeed; Tu, Chuqiao; Louie, Angelique Y.; Kauzlarich, Susan M.

2012-01-01

We demonstrate the synthesis of water-soluble allylamine terminated Fe doped Si (SixFe) nanoparticles as bimodal agents for optical and magnetic imaging. The preparation involves the synthesis of a single source iron containing precursor, Na4Si4 with x% Fe (x = 1, 5, 10), and its subsequent reaction with NH4Br to produce hydrogen terminated SixFe nanoparticles. The hydrogen-capped nanoparticles are further terminated with allylamine via thermal hydrosilylation. Transmission electron microscopy (TEM) indicates that the average particle diameter is ~3.0±1.0 nm. The Si5Fe nanoparticles show strong photoluminescence quantum yield in water (~ 10 %) with significant T2 contrast (r2/r1value of 4.31). Electron paramagnetic resonance (EPR) and Mössbauer spectroscopies indicate that iron in the nanoparticles is in the +3 oxidation state. Analysis of cytotoxicity using the resazurin assay on HepG2 liver cells indicates that the particles have minimal toxicity. PMID:22616623

Development of iron-doped silicon nanoparticles as bimodal imaging agents.

PubMed

Singh, Mani P; Atkins, Tonya M; Muthuswamy, Elayaraja; Kamali, Saeed; Tu, Chuqiao; Louie, Angelique Y; Kauzlarich, Susan M

2012-06-26

We demonstrate the synthesis of water-soluble allylamine-terminated Fe-doped Si (Si(xFe)) nanoparticles as bimodal agents for optical and magnetic imaging. The preparation involves the synthesis of a single-source iron-containing precursor, Na(4)Si(4) with x% Fe (x = 1, 5, 10), and its subsequent reaction with NH(4)Br to produce hydrogen-terminated Si(xFe) nanoparticles. The hydrogen-capped nanoparticles are further terminated with allylamine via thermal hydrosilylation. Transmission electron microscopy indicates that the average particle diameter is ∼3.0 ± 1.0 nm. The Si(5Fe) nanoparticles show strong photoluminescence quantum yield in water (∼10%) with significant T(2) contrast (r(2)/r(1) value of 4.31). Electron paramagnetic resonance and Mössbauer spectroscopies indicate that iron in the nanoparticles is in the +3 oxidation state. Analysis of cytotoxicity using the resazurin assay on HepG2 liver cells indicates that the particles have minimal toxicity.

Palladium nanoparticles deposited on silanized halloysite nanotubes: synthesis, characterization and enhanced catalytic property

PubMed Central

Zhang, Yi; He, Xi; Ouyang, Jing; Yang, Huaming

2013-01-01

Palladium (Pd) nanoparticles were deposited on the surface of halloysite nanotubes (HNTs) modified with γ-aminopropyltriethoxysilane (APTES) to produce Pd/NH2-HNTs nanocomposites. The results indicated that Pd nanoparticles were densely immobilized onto NH2-HNTs with an average diameter of ~ 3 nm. The Pd distribution on the surface of silanized HNTs showed much more uniform, and the Pd nanoparticle size became smaller compared with those directly deposited onto HNTs without silanization. Systematic characterization demonstrated that APTES were chemically bonded onto HNTs, and further confirmed the bond formation between Pd and -NH2 groups, which could ensure the firm deposit of Pd nanoparticles on the surface of silanized HNTs. The as-synthesized Pd/NH2-HNTs exhibited an excellent catalytic activity in the liquid-phase hydrogenation of styrene to ethylbenzene with full conversion within 30 min. The mechanism of the deposit of Pd nanoparticles on silanized HNTs was also investigated. PMID:24126604

Preparation of novel stable antibacterial nanoparticles using hydroxyethylcellulose and application in paper.

PubMed

Wei, Dafu; Chen, Yan; Zhang, Youwei

2016-01-20

Taking advantage of the self-assembly between the components, novel stable antibacterial nanoparticles were efficiently fabricated via a facile one-step co-polymerization of acrylic acid (AA) and N,N'-methylenebisacrylamide (MBA) on a mixed aqueous solution of poly(hexamethylene guanidine hydrochloride) (PHMG) and hydroxyethylcellulose (HEC). The z-average hydrodynamic diameters of the nanoparticles ranged from 220 nm to 450 nm. The inner layer of the nanoparticles is composed of water-insoluble interpolymer complexes of PHMG and PAA networks, while the outer layer is composed of PHMG and HEC. The nanoparticles are stabilized by electrostatic interactions, hydrogen bonding interactions, and the chemical bonds. The nanoparticle solution remained stable in a wide pH range of 2.0-12.0 and at salt concentrations below 0.25 mol/L. The nanoparticles were incorporated into handsheets using a dipping treatment. The resulted handsheets exhibited excellent antimicrobial activities even after multiple water washing treatments. The nanoparticles are promising in fabricating paper, water-based coatings and textiles with permanent antibacterial activity. Copyright © 2015 Elsevier Ltd. All rights reserved.

Mixed Phytochemicals Mediated Synthesis of Multifunctional Ag-Au-Pd Nanoparticles for Glucose Oxidation and Antimicrobial Applications.

PubMed

Rao, K Jagajjanani; Paria, Santanu

2015-07-01

The growing awareness toward the environment is increasing commercial demand for nanoparticles by green route syntheses. In this study, alloy-like Ag-Au-Pd trimetallic nanoparticles have been prepared by two plants extracts Aegle marmelos leaf (LE) and Syzygium aromaticum bud extracts (CE). Compositionally different Ag-Au-Pd nanoparticles with an atomic ratio of 5.26:2.16:1.0 (by LE) and 11.36:13.14:1.0 (by LE + CE) of Ag:Au:Pd were easily synthesized within 10 min at ambient conditions by changing the composition of phytochemicals. The average diameters of the nanoparticles by LE and LE + CE are ∼8 and ∼11 nm. The catalytic activity of the trimetallic nanoparticles was studied, and they were found to be efficient catalysts for the glucose oxidation process. The prepared nanoparticles also exhibited efficient antibacterial activity against a model Gram-negative bacteria Escherichia coli. The catalytic and antimicrobial properties of these readymade trimetallic nanoparticles have high possibility to be utilized in diverse fields of applications such as health care to environmental.

The effect of silver nanoparticles on composite shear bond strength to dentin with different adhesion protocols.

PubMed

Fatemeh, Koohpeima; Mohammad Javad, Mokhtari; Samaneh, Khalafi

2017-01-01

The purpose of this study was to investigate the effect of silver nanoparticles on composite shear bond strength using one etch and rinse and one self-etch adhesive systems. Silver nanoparticles were prepared. Transmission electron microscope and X-ray diffraction were used to characterize the structure of the particles. Nanoparticles were applied on exposed dentin and then different adhesives and composites were applied. All samples were tested by universal testing machine and shear bond strength was assesed. Particles with average diameter of about 20 nm and spherical shape were found. Moreover, it was shown that pretreatment by silver nanoparticles enhanced shear bond strength in both etch and rinse, and in self-etch adhesive systems (p≤0.05). Considering the positive antibacterial effects of silver nanoparticles, using them is recommended in restorative dentistry. It seems that silver nanoparticles could have positive effects on bond strength of both etch-and-rinse and self-etch adhesive systems. The best results of silver nanoparticles have been achieved with Adper Single Bond and before acid etching.

One-pot synthesis of pegylated ultrasmall iron-oxide nanoparticles and their in vivo evaluation as magnetic resonance imaging contrast agents.

PubMed

Lutz, Jean-François; Stiller, Sabrina; Hoth, Ann; Kaufner, Lutz; Pison, Ulrich; Cartier, Régis

2006-11-01

A well-defined copolymer poly(oligo(ethylene glycol) methacrylate-co-methacrylic acid) P(OEGMA-co-MAA) was studied as a novel water-soluble biocompatible coating for superparamagnetic iron oxide nanoparticles. This copolymer was prepared via a two-step procedure: a well-defined precursor poly(oligo(ethylene glycol) methacrylate-co-tert-butyl methacrylate), P(OEGMA-co-tBMA) (M(n) = 17300 g mol(-1); M(w)/M(n) = 1.22), was first synthesized by atom-transfer radical polymerization in the presence of the catalyst system copper(I) chloride/2,2'-bipyridyl and subsequently selectively hydrolyzed in acidic conditions. The resulting P(OEGMA-co-MAA) was directly utilized as a polymeric stabilizer in the nanoparticle synthesis. Four batches of ultrasmall PEGylated magnetite nanoparticles (i.e., with an average diameter below 30 nm) were prepared via aqueous coprecipitation of iron salts in the presence of variable amounts of P(OEGMA-co-MAA). The diameter of the nanoparticles could be easily tuned in the range 10-25 nm by varying the initial copolymer concentration. Moreover, the formed PEGylated ferrofluids exhibited a long-term colloidal stability in physiological buffer and could therefore be studied in vivo by magnetic resonance (MR) imaging. Intravenous injection into rats showed no detectable signal in the liver within the first 2 h. Maximum liver accumulation was found after 6 h, suggesting a prolongated circulation of the nanoparticles in the bloodstream as compared to conventional MR imaging contrast agents.

Modeling Nanoparticle Wrapping or Translocation in Bilayer Membranes

PubMed Central

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

2015-01-01

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

Controlling Growth High Uniformity Indium Selenide (In2Se3) Nanowires via the Rapid Thermal Annealing Process at Low Temperature.

PubMed

Hsu, Ya-Chu; Hung, Yu-Chen; Wang, Chiu-Yen

2017-09-15

High uniformity Au-catalyzed indium selenide (In 2 Se 3) nanowires are grown with the rapid thermal annealing (RTA) treatment via the vapor-liquid-solid (VLS) mechanism. The diameters of Au-catalyzed In 2 Se 3 nanowires could be controlled with varied thicknesses of Au films, and the uniformity of nanowires is improved via a fast pre-annealing rate, 100 °C/s. Comparing with the slower heating rate, 0.1 °C/s, the average diameters and distributions (standard deviation, SD) of In 2 Se 3 nanowires with and without the RTA process are 97.14 ± 22.95 nm (23.63%) and 119.06 ± 48.75 nm (40.95%), respectively. The in situ annealing TEM is used to study the effect of heating rate on the formation of Au nanoparticles from the as-deposited Au film. The results demonstrate that the average diameters and distributions of Au nanoparticles with and without the RTA process are 19.84 ± 5.96 nm (30.00%) and about 22.06 ± 9.00 nm (40.80%), respectively. It proves that the diameter size, distribution, and uniformity of Au-catalyzed In 2 Se 3 nanowires are reduced and improved via the RTA pre-treated. The systemic study could help to control the size distribution of other nanomaterials through tuning the annealing rate, temperatures of precursor, and growth substrate to control the size distribution of other nanomaterials. Graphical Abstract Rapid thermal annealing (RTA) process proved that it can uniform the size distribution of Au nanoparticles, and then it can be used to grow the high uniformity Au-catalyzed In 2 Se 3 nanowires via the vapor-liquid-solid (VLS) mechanism. Comparing with the general growth condition, the heating rate is slow, 0.1 °C/s, and the growth temperature is a relatively high growth temperature, > 650 °C. RTA pre-treated growth substrate can form smaller and uniform Au nanoparticles to react with the In 2 Se 3 vapor and produce the high uniformity In 2 Se 3 nanowires. The in situ annealing TEM is used to realize the effect of heating rate on Au nanoparticle formation from the as-deposited Au film. The byproduct of self-catalyzed In 2 Se 3 nanoplates can be inhibited by lowering the precursors and growth temperatures.

Physical and anti-microbial characteristics of carbon nanoparticles prepared from lamp soot

NASA Astrophysics Data System (ADS)

Mohanty, B.; Verma, Anita K.; Claesson, P.; Bohidar, H. B.

2007-11-01

Soot originating from the burning of butter and mustard oil in a lamp with a cotton wick was collected on a brass plate and dispersed in water and carbon tetrachloride (CCl4) as naked, and as Gum Arabic (GA, a anionic polyelectrolyte)-coated nanoparticles in water. They were physically characterized, and their anti-bacterial activities were probed on gram positive and negative bacterial colonies. TEM data revealed the presence of 35-55 nm diameter spherical carbon nanoparticles in water and CCl4. The dynamic light scattering determined the average hydrodynamic diameter for the same samples, which was found to be ≈100 nm (in CCl4) and ≈240 nm (in water), implying the packing of these nanoparticles into clusters. GA-coated particles yielded stable suspensions in water, but the clusters were almost the same in size (≈250 nm). The zeta potential distributions of the naked and the GA-coated nanoparticles were found to be unimodal and bimodal, respectively, with both yielding mean zeta potential values nearly equal to zero. Results of energy-dispersive x-ray analysis (EDAX) confirmed the absence of toxic metallic elements inside the specimen. X-ray diffraction study confirmed the presence of amorphous as well as graphitized carbon in these nanostructures. The anti-microbial activities in terms of growth inhibition for the carbon nanoparticles against Staphylococcus aureus, ATCC 13709 (native strain) and Klebsiella pneumonia ATCC 29655 (native strain) were assayed in agar gel. In vitro testing revealed significant anti-microbial activity against Klebsiella pneumonia, but carbon nanoparticles were unable to kill Staphylococcus aureus.

Synthesis, spectroscopic, structural and optical studies of Ru2S3 nanoparticles prepared from single-source molecular precursors

NASA Astrophysics Data System (ADS)

Mbese, Johannes Z.; Ajibade, Peter A.

2017-09-01

Homonuclear tris-dithiocarbamato ruthenium(III) complexes, [Ru(S2CNR2)3] were prepared and characterized by spectroscopic techniques and thermogravimetric analyses. The thermogravimetric analyses (TGA) of the ruthenium complexes showed that the complexes decompose to ruthenium(III) sulfide nanoparticles. The ruthenium(III) complexes were dispersed in oleic acid and thermolysed in hexadecylamine to prepared oleic acid/hexadecylamine capped Ru2S3 nanoparticles. FTIR revealed that Ru2S3 nanoparticles are capped through the interaction of the -NH2 group of hexadecylamine HDA adsorbed on the surfaces of nanoparticles and it also showed that oleic acid (OA) is acting as both coordinating stabilizing surfactant and capping agent. EDS spectra revealed that the prepared nanoparticles are mainly composed of Ru and S, confirming the formation of Ru2S3 nanoparticles. Powder XRD confirms that the nanoparticles are in cubic phase. The inner morphology of nanoparticles obtained from transmission electron microscopy (TEM) showed nanoparticles with narrow particle size distributions characterized by an average diameter of 8.45 nm with a standard deviation of 1.6 nm. The optical band gap (Eg) determined from Tauc plot are in the range 3.44-4.18 eV.

Synthesis of Metal Nanoparticles and Metal Fluoride Nanoparticles from Metal Amidinate Precursors in 1-Butyl-3-Methylimidazolium Ionic Liquids and Propylene Carbonate.

PubMed

Schütte, Kai; Barthel, Juri; Endres, Manuel; Siebels, Marvin; Smarsly, Bernd M; Yue, Junpei; Janiak, Christoph

2017-02-01

Decomposition of transition-metal amidinates [M{MeC(N i Pr) 2 } n ] [M(AMD) n ; M=Mn II , Fe II , Co II , Ni II , n= 2; Cu I , n= 1) induced by microwave heating in the ionic liquids (ILs) 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIm][BF 4 ]), 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIm][PF 6 ]), 1-butyl-3-methylimidazolium trifluoromethanesulfonate (triflate) ([BMIm][TfO]), and 1-butyl-3-methylimidazolium tosylate ([BMIm][Tos]) or in propylene carbonate (PC) gives transition-metal nanoparticles (M-NPs) in non-fluorous media (e.g. [BMIm][Tos] and PC) or metal fluoride nanoparticles (MF 2 -NPs) for M=Mn, Fe, and Co in [BMIm][BF 4 ]. FeF 2 -NPs can be prepared upon Fe(AMD) 2 decomposition in [BMIm][BF 4 ], [BMIm][PF 6 ], and [BMIm][TfO]. The nanoparticles are stable in the absence of capping ligands (surfactants) for more than 6 weeks. The crystalline phases of the metal or metal fluoride synthesized in [BMIm][BF 4 ] were identified by powder X-ray diffraction (PXRD) to exclusively Ni- and Cu-NPs or to solely MF 2 -NPs for M=Mn, Fe, and Co. The size and size dispersion of the nanoparticles were determined by transmission electron microscopy (TEM) to an average diameter of 2(±2) to 14(±4) nm for the M-NPs, except for the Cu-NPs in PC, which were 51(±8) nm. The MF 2 -NPs from [BMIm][BF 4 ] were 15(±4) to 65(±18) nm. The average diameter from TEM is in fair agreement with the size evaluated from PXRD with the Scherrer equation. The characterization was complemented by energy-dispersive X-ray spectroscopy (EDX). Electrochemical investigations of the CoF 2 -NPs as cathode materials for lithium-ion batteries were simply evaluated by galvanostatic charge/discharge profiles, and the results indicated that the reversible capacity of the CoF 2 -NPs was much lower than the theoretical value, which may have originated from the complex conversion reaction mechanism and residue on the surface of the nanoparticles.

EPR and Structural Characterization of Water-Soluble Mn2+-Doped Si Nanoparticles

PubMed Central

2016-01-01

Water-soluble poly(allylamine) Mn2+-doped Si (SiMn) nanoparticles (NPs) were prepared and show promise for biologically related applications. The nanoparticles show both strong photoluminescence and good magnetic resonance contrast imaging. The morphology and average diameter were obtained through transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM); spherical crystalline Si NPs with an average diameter of 4.2 ± 0.7 nm were observed. The doping maximum obtained through this process was an average concentration of 0.4 ± 0.3% Mn per mole of Si. The water-soluble SiMn NPs showed a strong photoluminescence with a quantum yield up to 13%. The SiMn NPs had significant T1 contrast with an r1 relaxivity of 11.1 ± 1.5 mM–1 s–1 and r2 relaxivity of 32.7 ± 4.7 mM–1 s–1 where the concentration is in mM of Mn2+. Dextran-coated poly(allylamine) SiMn NPs produced NPs with T1 and T2 contrast with a r1 relaxivity of 27.1 ± 2.8 mM–1 s–1 and r2 relaxivity of 1078.5 ± 1.9 mM–1 s–1. X-band electron paramagnetic resonance spectra are fit with a two-site model demonstrating that there are two types of Mn2+ in these NP’s. The fits yield hyperfine splittings (A) of 265 and 238 MHz with significant zero field splitting (D and E terms). This is consistent with Mn in sites of symmetry lower than tetrahedral due to the small size of the NP’s. PMID:28154618

Tuning of optical properties of CdS nanoparticles synthesized in a glass matrix

NASA Astrophysics Data System (ADS)

Popov, Ivan D.; Kuznetsova, Yulia V.; Rempel, Svetlana V.; Rempel, Andrey A.

2018-03-01

Attempts were made to provide the data concerning directed synthesis of semiconductor nanoparticles in a dielectric silica-based glass matrix. These attempts involve finding out the connections between the structure, size of CdS nanoparticles, and optical properties of the nanocomposites produced. High-resolution focused ion beam scanning electron microscopy images of CdS nanoparticles incorporated in glass and SAXS results confirm the formation of uniformly distributed spherical CdS nanoparticles with an average diameter of about 6.2 nm. UV-Vis measurements show that CdS composites possess a direct bandgap wider than 2.45 eV depending on the heat treatment conditions; thus, heat treatment can be used to control nanoparticle size in each selected composite. The emission spectra showed a maximum at about 603 nm and a red shift of about 100 nm with increasing annealing temperature that is associated with the presence of defect states in the nanoparticles. In addition, semiconductor phase concentration in the glass matrix was found by using optical absorption data for the first time, which allows understanding the effect of nanocomposite structure on luminescence properties.

Microwave assisted facile green synthesis of silver and gold nanocatalysts using the leaf extract of Aerva lanata.

PubMed

Joseph, Siby; Mathew, Beena

2015-02-05

Herein, we report a simple microwave assisted method for the green synthesis of silver and gold nanoparticles by the reduction of aqueous metal salt solutions using leaf extract of the medicinal plant Aerva lanata. UV-vis., FTIR, XRD, and HR-TEM studies were conducted to assure the formation of nanoparticles. XRD studies clearly confirmed the crystalline nature of the synthesized nanoparticles. From the HR-TEM images, the silver nanoparticles (AgNPs) were found to be more or less spherical and gold nanoparticles (AuNPs) were observed to be of different morphology with an average diameter of 18.62nm for silver and 17.97nm for gold nanoparticles. In order to evaluate the effect of microwave heating upon rate of formation, the synthesis was also conducted under ambient condition without the assistance of microwave radiation and the former method was found to be much faster than the later. The synthesized nanoparticles were used as nanocatalysts in the reduction of 4-nitrophenol to 4-aminophenol by NaBH4. Copyright © 2014 Elsevier B.V. All rights reserved.

Characterization of Aerosols of Titanium Dioxide Nanoparticles Following Three Generation Methods Using an Optimized Aerosolization System Designed for Experimental Inhalation Studies

PubMed Central

Pujalté, Igor; Serventi, Alessandra; Noël, Alexandra; Dieme, Denis; Haddad, Sami; Bouchard, Michèle

2017-01-01

Nanoparticles (NPs) can be released in the air in work settings, but various factors influence the exposure of workers. Controlled inhalation experiments can thus be conducted in an attempt to reproduce real-life exposure conditions and assess inhalation toxicology. Methods exist to generate aerosols, but it remains difficult to obtain nano-sized and stable aerosols suitable for inhalation experiments. The goal of this work was to characterize aerosols of titanium dioxide (TiO2) NPs, generated using a novel inhalation system equipped with three types of generators—a wet collision jet nebulizer, a dry dust jet and an electrospray aerosolizer—with the aim of producing stable aerosols with a nano-diameter average (<100 nm) and monodispersed distribution for future rodent exposures and toxicological studies. Results showed the ability of the three generation systems to provide good and stable dispersions of NPs, applicable for acute (continuous up to 8 h) and repeated (21-day) exposures. In all cases, the generated aerosols were composed mainly of small aggregates/agglomerates (average diameter <100 nm) with the electrospray producing the finest (average diameter of 70–75 mm) and least concentrated aerosols (between 0.150 and 2.5 mg/m3). The dust jet was able to produce concentrations varying from 1.5 to 150 mg/m3, and hence, the most highly concentrated aerosols. The nebulizer collision jet aerosolizer was the most versatile generator, producing both low (0.5 mg/m3) and relatively high concentrations (30 mg/m3). The three optimized generators appeared suited for possible toxicological studies of inhaled NPs. PMID:29051446

Rapid microwave-assisted synthesis of sub-30nm lipid nanoparticles.

PubMed

Dunn, Stuart S; Beckford Vera, Denis R; Benhabbour, S Rahima; Parrott, Matthew C

2017-02-15

Accessing the phase inversion temperature by microwave heating may enable the rapid synthesis of small lipid nanoparticles. Nanoparticle formulations consisted of surfactants Brij 78 and Vitamin E TPGS, and trilaurin, trimyristin, or miglyol 812 as nanoparticle lipid cores. Each formulation was placed in water and heated by microwave irradiation at temperatures ranging from 65°C to 245°C. We observed a phase inversion temperature (PIT) for these formulations based on a dramatic decrease in particle Z-average diameters. Subsequently, nanoparticles were manufactured above and below the PIT and studied for (a) stability toward dilution, (b) stability over time, (c) fabrication as a function of reaction time, and (d) transmittance of lipid nanoparticle dispersions. Lipid-based nanoparticles with distinct sizes down to 20-30nm and low polydispersity could be attained by a simple, one-pot microwave synthesis. This was carried out by accessing the phase inversion temperature using microwave heating. Nanoparticles could be synthesized in just one minute and select compositions demonstrated high stability. The notable stability of these particles may be explained by the combination of van der Waals interactions and steric repulsion. 20-30nm nanoparticles were found to be optically transparent. Published by Elsevier Inc.

Photoinduced silver nanoparticles/nanorings on plasmid DNA scaffolds.

PubMed

Liu, Jianhua; Zhang, Xiaoliang; Yu, Mei; Li, Songmei; Zhang, Jindan

2012-01-23

Biological scaffolds are being actively explored for the synthesis of nanomaterials with novel structures and unexpected properties. Toroidal plasmid DNA separated from the Bacillus host is applied as a sacrificial mold for the synthesis of silver nanoparticles and nanorings. The photoirradiation method is applied to reduce Ag(I) on the plasmid. The nanoparticles are obtained by varying the concentration of the Ag(I) ion solution and the exposure time of the plasmid-Ag(I) complex under UV light at 254 nm and room temperature. It is found that the plasmid serves not only as a template but also as a reductant to drive the silver nucleation and deposition. The resulting nanoparticles have a face-centered cubic (fcc) crystal structure and 20-30 nm average diameter. The detailed mechanism is discussed, and other metals or alloys could also be synthesized with this method. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effects of para-substituents of styrene derivatives on their chemical reactivity on platinum nanoparticle surfaces

NASA Astrophysics Data System (ADS)

Hu, Peiguang; Chen, Limei; Deming, Christopher P.; Lu, Jia-En; Bonny, Lewis W.; Chen, Shaowei

2016-06-01

Stable platinum nanoparticles were successfully prepared by the self-assembly of para-substituted styrene derivatives onto the platinum surfaces as a result of platinum-catalyzed dehydrogenation and transformation of the vinyl groups to the acetylene ones, forming platinum-vinylidene/-acetylide interfacial bonds. Transmission electron microscopic measurements showed that the nanoparticles were well dispersed without apparent aggregation, suggesting sufficient protection of the nanoparticles by the organic capping ligands, and the average core diameter was estimated to be 2.0 +/- 0.3 nm, 1.3 +/- 0.2 nm, and 1.1 +/- 0.2 nm for the nanoparticles capped with 4-tert-butylstyrene, 4-methoxystyrene, and 4-(trifluoromethyl)styrene, respectively, as a result of the decreasing rate of dehydrogenation with the increasing Taft (polar) constant of the para-substituents. Importantly, the resulting nanoparticles exhibited unique photoluminescence, where an increase of the Hammett constant of the para-substituents corresponded to a blue-shift of the photoluminescence emission, suggesting an enlargement of the HOMO-LUMO band gap of the nanoparticle-bound acetylene moieties. Furthermore, the resulting nanoparticles exhibited apparent electrocatalytic activity towards oxygen reduction in acidic media, with the best performance among the series of samples observed with the 4-tert-butylstyrene-capped nanoparticles due to an optimal combination of the nanoparticle core size and ligand effects on the bonding interactions between platinum and oxygen species.Stable platinum nanoparticles were successfully prepared by the self-assembly of para-substituted styrene derivatives onto the platinum surfaces as a result of platinum-catalyzed dehydrogenation and transformation of the vinyl groups to the acetylene ones, forming platinum-vinylidene/-acetylide interfacial bonds. Transmission electron microscopic measurements showed that the nanoparticles were well dispersed without apparent aggregation, suggesting sufficient protection of the nanoparticles by the organic capping ligands, and the average core diameter was estimated to be 2.0 +/- 0.3 nm, 1.3 +/- 0.2 nm, and 1.1 +/- 0.2 nm for the nanoparticles capped with 4-tert-butylstyrene, 4-methoxystyrene, and 4-(trifluoromethyl)styrene, respectively, as a result of the decreasing rate of dehydrogenation with the increasing Taft (polar) constant of the para-substituents. Importantly, the resulting nanoparticles exhibited unique photoluminescence, where an increase of the Hammett constant of the para-substituents corresponded to a blue-shift of the photoluminescence emission, suggesting an enlargement of the HOMO-LUMO band gap of the nanoparticle-bound acetylene moieties. Furthermore, the resulting nanoparticles exhibited apparent electrocatalytic activity towards oxygen reduction in acidic media, with the best performance among the series of samples observed with the 4-tert-butylstyrene-capped nanoparticles due to an optimal combination of the nanoparticle core size and ligand effects on the bonding interactions between platinum and oxygen species. Electronic supplementary information (ESI) available: TGA curves and additional voltammograms. See DOI: 10.1039/c6nr02296k

A new probe using hybrid virus-dye nanoparticles for near-infrared fluorescence tomography

NASA Astrophysics Data System (ADS)

Wu, Changfeng; Barnhill, Hannah; Liang, Xiaoping; Wang, Qian; Jiang, Huabei

2005-11-01

A fluorescent probe based on bionanoparticle cowpea mosaic virus has been developed for near-infrared fluorescence tomography. A unique advantage of this probe is that over 30 dye molecules can be loaded onto each viral nanoparticle with an average diameter of 30 nm, making high local dye concentration (∼1.8 mM) possible without significant fluorescence quenching. This ability of high loading of local dye concentration would increase the signal-to-noise ratio considerably, thus sensitivity for detection. We demonstrate successful tomographic fluorescence imaging of a target containing the virus-dye nanoparticles embedded in a tissue-like phantom. Tomographic fluorescence data were obtained through a multi-channel frequency-domain system and the spatial maps of fluorescence quantum yield were recovered with a finite-element-based reconstruction algorithm.

Antibacterial gold nanoparticles-biomass assisted synthesis and characterization.

PubMed

Badwaik, Vivek D; Willis, Chad B; Pender, Dillon S; Paripelly, Rammohan; Shah, Monic; Kherde, Yogesh A; Vangala, Lakshmisri M; Gonzalez, Matthew S; Dakshinamurthy, Rajalingam

2013-10-01

Xylose is a natural monosaccharide found in biomass such as straw, pecan shells, cottonseed hulls, and corncobs. Using this monosaccharide, we report the facile, green synthesis and characterization of stable xylose encapsulated gold nanoparticles (Xyl-GNPs) with potent antibacterial activity. Xyl-GNPs were synthesized using the reduction property of xylose in an aqueous solution containing choloraurate anions carried out at room temperature and atmospheric pressure. These nanoparticles were stable and near spherical in shape with an average diameter of 15 +/- 5 nm. Microbiological assay results showed the concentration dependent antibacterial activity of these particles against both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus epidermidis) bacteria. Thus the facile, environmentally friendly Xyl-GNPs have many potential applications in chemical and biomedical industries, particularly in the development of antibacterial agents in the field of biomedicine.

Plant-mediated synthesis of biosilver nanoparticles using Pandanus amaryllifolius extract and its bactericidal activity

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

Akhir, Rabiatuladawiyah Md.; Fairuzi, Afiza Ahmad; Ismail, Nur Hilwani

In this work, we describe a cost effective, easily scaled up and environmental friendly technique for green synthesis of silver nanoparticles (AgNPs) from 5 mM AgNO{sub 3} solution using aqueous extract of Pandanus amaryllifolius (P. amaryllifolius) leaves as reducing agent. Biosynthesized silver nanoparticles was confirmed by sampling the reaction mixture at regular intervals and the absorption maxima was scanned by Ultraviolet-Visible (UV-Vis) spectroscopy at wavelength of 200-500 nm. Images from Field Emission Scanning Electron Microscope (FESEM) have shown that the silver nanoparticles are 17-30 nm in range and assembled in mostly spherical shape. Elemental composition analysis by using Energy Dispersive X-ray (EDX) confirmedmore » the presence of silver. Low concentration of biosynthesized silver nanoparticles have been found to exhibit good antibacterial activity against Staphylococcus aureus bacteria with average mean diameter of zone of inhibition (ZOI) of 16 mm.« less

Green synthesis of silver nanoparticles from Moringa oleifera leaf extracts and its antimicrobial potential

NASA Astrophysics Data System (ADS)

Moodley, Jerushka S.; Babu Naidu Krishna, Suresh; Pillay, Karen; Sershen; Govender, Patrick

2018-03-01

In this study we report on the synthesis of silver nanoparticles (AgNPs) from the leaf extracts of Moringa oleifera using sunlight irradiation as primary source of energy, and its antimicrobial potential. Silver nanoparticle formation was confirmed by surface plasmon resonance at 450 nm and 440 nm, respectively for both fresh and freeze-dried leaf samples. Crystanality of AgNPs was confirmed by transmission electron microscopy, scanning electron microscopy with energy dispersive x-ray spectroscopy and Fourier transform infrared (FTIR) spectroscopy analysis. FTIR spectroscopic analysis suggested that flavones, terpenoids and polysaccharides predominate and are primarily responsible for the reduction and subsequent capping of AgNPs. X-ray diffraction analysis also demonstrated that the size range of AgNPs from both samples exhibited average diameters of 9 and 11 nm, respectively. Silver nanoparticles showed antimicrobial activity on both bacterial and fungal strains. The biosynthesised nanoparticle preparations from M. oleifera leaf extracts exhibit potential for application as broad-spectrum antimicrobial agents.

Synthesis and Luminescence Properties of Core/Shell ZnS:Mn/ZnO Nanoparticles.

PubMed

Jiang, Daixun; Cao, Lixin; Liu, Wei; Su, Ge; Qu, Hua; Sun, Yuanguang; Dong, Bohua

2009-01-01

In this paper the influence of ZnO shell thickness on the luminescence properties of Mn-doped ZnS nanoparticles is studied. Transmission electron microscopy (TEM) images showed that the average diameter of ZnS:Mn nanoparticles is around 14 nm. The formation of ZnO shells on the surface of ZnS:Mn nanoparticles was confirmed by X-ray diffraction (XRD) patterns, high-resolution TEM (HRTEM) images, and X-ray photoelectron spectroscopy (XPS) measurements. A strong increase followed by a gradual decline was observed in the room temperature photoluminescence (PL) spectra with the thickening of the ZnO shell. The photoluminescence excitation (PLE) spectra exhibited a blue shift in ZnO-coated ZnS:Mn nanoparticles compared with the uncoated ones. It is shown that the PL enhancement and the blue shift of optimum excitation wavelength are led by the ZnO-induced surface passivation and compressive stress on the ZnS:Mn cores.

Effect of Particle Size on Thermal Conductivity of Nanofluid

NASA Astrophysics Data System (ADS)

Chopkar, M.; Sudarshan, S.; Das, P. K.; Manna, I.

2008-07-01

Nanofluids, containing nanometric metallic or oxide particles, exhibit extraordinarily high thermal conductivity. It is reported that the identity (composition), amount (volume percent), size, and shape of nanoparticles largely determine the extent of this enhancement. In the present study, we have experimentally investigated the impact of Al2Cu and Ag2Al nanoparticle size and volume fraction on the effective thermal conductivity of water and ethylene glycol based nanofluid prepared by a two-stage process comprising mechanical alloying of appropriate Al-Cu and Al-Ag elemental powder blend followed by dispersing these nanoparticles (1 to 2 vol pct) in water and ethylene glycol with different particle sizes. The thermal conductivity ratio of nanofluid, measured using an indigenously developed thermal comparator device, shows a significant increase of up to 100 pct with only 1.5 vol pct nanoparticles of 30- to 40-nm average diameter. Furthermore, an analytical model shows that the interfacial layer significantly influences the effective thermal conductivity ratio of nanofluid for the comparable amount of nanoparticles.

The bipyridine adducts of N-phenyldithiocarbamato complexes of Zn(II) and Cd(II); synthesis, spectral, thermal decomposition studies and use as precursors for ZnS and CdS nanoparticles

NASA Astrophysics Data System (ADS)

Onwudiwe, Damian C.; Strydom, Christien A.

2015-01-01

Bipyridine adducts of N-phenyldithiocarbamato complexes, [ML12L2] (M = Cd(II), Zn(II); L1 = N-phenyldithiocarbamate, L2 = 2,2‧ bipyridine), have been synthesized and characterised. The decomposition of these complexes to metal sulphides has been investigated by thermogravimetric analysis (TGA). The complexes were used as single-source precursors to synthesize MS (M = Zn, Cd) nanoparticles (NPs) passivated by hexadecyl amine (HDA). The growth of the nanoparticles was carried out at two different temperatures: 180 and 220 °C, and the optical and structural properties of the nanoparticles were studied using UV-Vis spectroscopy, photoluminescence spectroscopy (PL), transmission emission microscopy (TEM) and powdered X-ray diffraction (p-XRD). Nanoparticles, whose average diameters are 2.90 and 3.54 nm for ZnS, and 8.96 and 9.76 nm for CdS grown at 180 and 220 °C respectively, were obtained.

In vitro evaluation of paclitaxel loaded amorphous chitin nanoparticles for colon cancer drug delivery.

PubMed

Smitha, K T; Anitha, A; Furuike, T; Tamura, H; Nair, Shantikumar V; Jayakumar, R

2013-04-01

Chitin and its derivatives have been widely used in drug delivery applications due to its biocompatible, biodegradable and non-toxic nature. In this study, we have developed amorphous chitin nanoparticles (150±50 nm) and evaluated its potential as a drug delivery system. Paclitaxel (PTX), a major chemotherapeutic agent was loaded into amorphous chitin nanoparticles (AC NPs) through ionic cross-linking reaction using TPP. The prepared PTX loaded AC NPs had an average diameter of 200±50 nm. Physico-chemical characterization of the prepared nanoparticles was carried out. These nanoparticles were proven to be hemocompatible and in vitro drug release studies showed a sustained release of PTX. Cellular internalization of the NPs was confirmed by fluorescent microscopy as well as by flow cytometry. Anticancer activity studies proved the toxicity of PTX-AC NPs toward colon cancer cells. These preliminary results indicate the potential of PTX-AC NPs in colon cancer drug delivery. Copyright © 2012 Elsevier B.V. All rights reserved.

"Synthesis, characterization and studies on antioxidant activity of silver nanoparticles using Elephantopus scaber leaf extract".

PubMed

Kharat, Sopan N; Mendhulkar, Vijay D

2016-05-01

The simple, eco-friendly and cost effective method of green synthesis of silver nanoparticle in the leaf extract of medicinal plant Elephantopus scaber L. is illustrated in the present work. The synthesized silver nanoparticles (AgNPs) were characterized with UV-Vis-spectroscopy, nanoparticle tracking analysis (NTA), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) analysis. The UV-spectra show maximum absorbance at 435 nm, NTA analysis shows 78 nm average sizes of nanoparticles, TEM analysis indicates spherical shape of the nanoparticles with the average diameter of 50 nm. The XRD peaks at 2θ range of 30-80° correspond to (111), (200), (220), (311) reflection planes that indicate the structure of metallic silver. FTIR analysis reveals surface capping of phenolic groups. Existence of peaks in the range of 1611 to 1400 cm(-1) indicates the presence of aromatic rings in the leaf extract. The peak at 1109 cm(-1) is due to the presence of OH groups. The antioxidant activity of synthesized nanoparticles was evaluated performing DPPH assay and it is observed that the photosynthesized nanoparticle also possesses antioxidant potentials. Thus, it can be used as potential free radical scavenger. Silver particles have tremendous applications in the field of diagnostics and therapeutics. To this context, the surface coating of plant metabolite constituents has great potentials. Therefore, the present work has been undertaken to synthesize the AgNPs using leaf extract of medicinal plant, E. scaber, to characterize and access their antioxidant properties. Copyright © 2016 Elsevier B.V. All rights reserved.

Synthesis of gold nanoparticles with graphene oxide.

PubMed

Wang, Wenshuo; He, Dawei; Zhang, Xiqing; Duan, Jiahua; Wu, Hongpeng; Xu, Haiteng; Wang, Yongsheng

2014-05-01

Single sheets of functionalized graphene oxide are derived through chemical exfoliation of natural flake graphite. We present an effective synthetic method of graphene-gold nanoparticles hybrid nanocomposites. AFM (Atomic Force Microscope) was used to measure the thickness of the individual GO nanosheet. FTIR (Fourier transform infrared) spectroscopy was used to verify the attachment of oxygen functionalities on the surface of graphene oxide. TEM (Transmission Electron Microscope) data revealed the average diameters of the gold colloids and characterized the composite particles situation. Absorption spectroscopy showed that before and after synthesis the gold particle size did not change. Our studies indicate that the hybrid is potential substrates for catalysts and biosensors.

Characterization and anticancer potential of ferulic acid-loaded chitosan nanoparticles against ME-180 human cervical cancer cell lines

NASA Astrophysics Data System (ADS)

Panwar, Richa; Sharma, Asvene K.; Kaloti, Mandeep; Dutt, Dharm; Pruthi, Vikas

2016-08-01

Ferulic acid (FA) is a widely distributed hydroxycinnamic acid found in various cereals and fruits exhibiting potent antioxidant and anticancer activities. However, due to low solubility and permeability, its availability to biological systems is limited. Non-toxic chitosan-tripolyphosphate pentasodium (CS-TPP) nanoparticles (NPs) are used to load sparingly soluble molecules and drugs, increasing their bioavailability. In the present work, we have encapsulated FA into the CS-TPP NPs to increase its potential as a therapeutic agent. Different concentrations of FA were tested to obtain optimum sized FA-loaded CS-TPP nanoparticles (FA/CS-TPP NPs) by ionic gelation method. Nanoparticles were characterized by scanning electron microscopy, Fourier transformation infrared spectroscopy (FTIR), thermogravimetric analyses and evaluated for their anticancer activity against ME-180 human cervical cancer cell lines. The FTIR spectra confirmed the encapsulation of FA and thermal analysis depicted its degradation profile. A concentration-dependent relationship between FA encapsulation efficiency and FA/CS-TPP NPs diameter was observed. Smooth and spherical FA-loaded cytocompatible nanoparticles with an average diameter of 125 nm were obtained at 40 µM FA conc. The cytotoxicity of 40 µM FA/CS-TPP NPs against ME-180 cervical cancer cell lines was found to be higher as compared to 40 µM native FA. Apoptotic morphological changes as cytoplasmic remnants and damaged wrinkled cells in ME-180 cells were visualized using scanning electron microscopic and fluorescent microscopic techniques. Data concluded that chitosan enveloped FA nanoparticles could be exploited as an excellent therapeutic drug against cancer cells proliferation.

Temperature-responsive magnetite/PEO-PPO-PEO block copolymer nanoparticles for controlled drug targeting delivery.

PubMed

Chen, Shu; Li, Ying; Guo, Chen; Wang, Jing; Ma, Junhe; Liang, Xiangfeng; Yang, Liang-Rong; Liu, Hui-Zhou

2007-12-04

In this study, temperature-responsive magnetite/polymer nanoparticles were developed from iron oxide nanoparticles and poly(ethyleneimine)-modified poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) block copolymer. The particles were characterized by TEM, XRD, DLS, VSM, FTIR, and TGA. A typical product has an approximately 20 nm magnetite core and an approximately 40 nm hydrodynamic diameter with a narrow size distribution and is superparamagnetic with large saturation magnetization (51.34 emu/g) at room temperature. The most attractive feature of the nanoparticles is their temperature-responsive volume-transition property. DLS results indicated that their average hydrodynamic diameter underwent a sharp decrease from 45 to 25 nm while evaluating the temperature from 20 to 35 degrees C. The temperature-dependent evolution of the C-O stretching band in the FTIR spectra of the aqueous nanoparticles solution revealed that thermo-induced self-assembly of the immobilized block copolymers occurred on the magnetite solid surfaces, which is accompanied by a conformational change from a fully extended state to a highly coiled state of the copolymer. Consequently, the copolymer shell could act as a temperature-controlled "gate" for the transit of guest substance. The uptake and release of both hydrophobic and hydrophilic model drugs were well controlled by switching the transient opening and closing of the polymer shell at different temperatures. A sustained release of about 3 days was achieved in simulated human body conditions. In primary mouse experiments, drug-entrapped magnetic nanoparticles showed good biocompatibility and effective therapy for spinal cord damage. Such intelligent magnetic nanoparticles are attractive candidates for widespread biomedical applications, particularly in controlled drug-targeting delivery.

Workplace performance of a loose-fitting powered air purifying respirator during nanoparticle synthesis

NASA Astrophysics Data System (ADS)

Koivisto, Antti J.; Aromaa, Mikko; Koponen, Ismo K.; Fransman, Wouter; Jensen, Keld A.; Mäkelä, Jyrki M.; Hämeri, Kaarle J.

2015-04-01

Nanoparticle (particles with diameter ≤100 nm) exposure is recognized as a potentially harmful size fraction for pulmonary particle exposure. During nanoparticle synthesis, the number concentrations in the process room may exceed 10 × 106 cm-3. During such conditions, it is essential that the occupants in the room wear highly reliable high-performance respirators to prevent inhalation exposure. Here we have studied the in-use program protection factor (PPF) of loose-fitting powered air purifying respirators, while workers were coating components with TiO2 or Cu x O y nanoparticles under a hood using a liquid flame spray process. The PPF was measured using condensation particle counters, an electrical low pressure impactor, and diffusion chargers. The room particle concentrations varied from 4 × 106 to 40 × 106 cm-3, and the count median aerodynamic diameter ranged from 32 to 180 nm. Concentrations inside the respirator varied from 0.7 to 7.2 cm-3. However, on average, tidal breathing was assumed to increase the respirator concentration by 2.3 cm-3. The derived PPF exceeded 1.1 × 106, which is more than 40 × 103 times the respirator assigned protection factor. We were unable to measure clear differences in the PPF of respirators with old and new filters, among two male and one female user, or assess most penetrating particle size. This study shows that the loose-fitting powered air purifying respirator provides very efficient protection against nanoparticle inhalation exposure if used properly.

Fabrication and evaluation of SDF-1 loaded galactosylated chitosan nanoparticles for liver targeting

NASA Astrophysics Data System (ADS)

Xue-Hui, Chu; Zhang-Qi, Feng; Qian, Xu; Jiang-Qiang, Xiao; Xian-Wen, Yuan; Xi-Tai, Sun

2017-03-01

Objective. SDF-1 loaded galactosylated chitosan (GC) nanoparticles for liver targeting were synthesized by electrospraying technique, and its biocompatibility and liver targeting effect were evaluated. Method. The SDF-1 loaded GC nanoparticles were constructed and its morphology was observed by the scanning electron microscopy (SEM). Hepatocytes were harvested and cocultured with the nanoparticles, and the albumin secretion and urea synthesis were detected by enzyme-linked immunosorbent assay assay, the concentration of lactate dehydrogenase (LDH) and tumor necrosis factor-α (TNF-α) was also measured. Finally, the nanoparticles were injected intravenously through the caudal vein of rat, and its liver targeting effect was evaluated. Result. SEM showed the nanoparticles distributed uniformly, with an average diameter of 100 nm and a regular spherical shape. There was no significant difference in urea synthesis, albumin secretion, concentration of LDH and TNF-α between two groups (p > 0.05). The nanoparticles were significantly accumulated in the liver tissue after its injection, but seldom fluorescence signals were observed in the lung, spleen, heart and kidney. Conclusion. The SDF-1 loaded GC nanoparticles showed uniform distribution, good biocompatibility and liver targeting effect, and suggested its potential application as a liver targeting delivery system.

SiO(x) nanoparticles synthesized by an evaporation and condensation process using induction melting of silicon and gas injection.

PubMed

Jang, Bo Yun; Lee, Jin Seok; Kim, Joon Soo

2013-05-01

SiO(x) nanoparticles were synthesized using a specially designed induction melting system equipped with a segmented graphite crucible. The graphite crucible with the segmented wall was the key to enhancing the evaporation rate due to the increase of the evaporation area and convection of the silicon melt. Injection of the gas mixture of oxygen (O2) and argon (Ar) on silicon (Si) melt caused the formation of SiO(x) nanoparticles. The evaporated SiO(x) nanoparticles were then cooled and condensed in a process chamber. The effects of the O2/Ar ratio in the injection gas on the microstructures of the SiO(x) nanoparticles were then investigated. Synthesized SiO(x) nanoparticles were proven to be of a homogeneous amorphous phase with average diameters of 30-35 nm. The microstructures were independent from the O2/Ar ratio of the injected gas. However, x increased from 1.36 to 1.84 as the O2/Ar ratio increased. The purity of the synthesized nanoparticles was about 99.9%. SiO(x) nanoparticles could be applied as the active anode material in a lithium (Li) ion secondary battery.

Development and in vitro evaluation of oxytetracycline-loaded PMMA nanoparticles for oral delivery against anaplasmosis.

PubMed

SadguruPrasad, Lakshminarayana Turuvekere; Madhusudhan, Basavaraj; Kodihalli B, Prakash; Ghosh, Prahlad Chandra

2017-02-01

Poly-methyl methacrylate (PMMA) polymer with remarkable properties and merits are being preferred in various biomedical applications due to its biocompatibility, non-toxicity and cost effectiveness. In this investigation, oxytetracycline-loaded PMMA nanoparticles were prepared using nano-precipitation method for the treatment of anaplasmosis. The prepared nanoparticles were characterised using dynamic light scattering (DLS), atomic force microscopy (AFM), differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy. The mean average diameter of the nanoparticles ranged between 190-240 nm and zeta potential was found to be -19 mV. The drug loading capacity and entrapment efficiency of nanoparticles was found varied between 33.7-62.2% and 40.5-60.0%. The in vitro drug release profile exhibited a biphasic phenomenon indicating controlled drug release. The uptake of coumarin-6(C-6)-loaded PMMA nanoparticles in Plasmodium falciparum ( Pf 3D7) culture model was studied. The preferential uptake of C-6-loaded nanoparticles by the Plasmodium infected erythrocytes in comparison with the uninfected erythrocytes was observed under fluorescence microscopy. These findings suggest that oxytetracycline-loaded PMMA nanoparticles were found to be an effective oral delivery vehicle and an alternative pharmaceutical formulation in anaplasmosis treatment, too.

Optical Degradation of Colloidal Eu-Complex Embedded in Silica Glass Film Using Reprecipitation and Sol-Gel Methods.

PubMed

Fukuda, Takeshi; Kurabayashi, Tomokazu; Yamaki, Tatsuki

2016-04-01

A reprecipitation method has been investigated for fabricating colloidal nanoparticles using Eu-complex. Herein, we investigated optical degradation characteristics of (1,10-phenanthroline)tris [4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedionato]europium(III) colloidal nanoparticles, which were embedded into a silica glass film fabricated by a conventional sol-gel process. At first, we tried several types of good solvents for the reprecipitation method, and dimethyl sulfoxide (DMSO) is found to be a suitable solvent for realizing the small diameter and the high long-term stability against the ultraviolet irradiation even though the boing point of DMSO is higher than that of water used as a poor solvent. By optimizing the good solvent and the concentration of Eu-complex, the relative photoluminescence intensity of 0.96 was achieved even though the ultraviolet light was continuously irradiated for 90 min. In addition, the average diameter of 106 nm was achieved when DMSO was used as a good solvent, resulting in the high transmittance at a visible wavelength region. Therefore, we can achieve the transparent emissive thin film with a center wavelength of 612 nm, and the optical degradation was drastically reduced by forming nanoparticles.

Pulsed Laser Ablation-Induced Green Synthesis of TiO2 Nanoparticles and Application of Novel Small Angle X-Ray Scattering Technique for Nanoparticle Size and Size Distribution Analysis.

PubMed

Singh, Amandeep; Vihinen, Jorma; Frankberg, Erkka; Hyvärinen, Leo; Honkanen, Mari; Levänen, Erkki

2016-12-01

This paper aims to introduce small angle X-ray scattering (SAXS) as a promising technique for measuring size and size distribution of TiO 2 nanoparticles. In this manuscript, pulsed laser ablation in liquids (PLAL) has been demonstrated as a quick and simple technique for synthesizing TiO 2 nanoparticles directly into deionized water as a suspension from titanium targets. Spherical TiO 2 nanoparticles with diameters in the range 4-35 nm were observed with transmission electron microscopy (TEM). X-ray diffraction (XRD) showed highly crystalline nanoparticles that comprised of two main photoactive phases of TiO 2 : anatase and rutile. However, presence of minor amounts of brookite was also reported. The traditional methods for nanoparticle size and size distribution analysis such as electron microscopy-based methods are time-consuming. In this study, we have proposed and validated SAXS as a promising method for characterization of laser-ablated TiO 2 nanoparticles for their size and size distribution by comparing SAXS- and TEM-measured nanoparticle size and size distribution. SAXS- and TEM-measured size distributions closely followed each other for each sample, and size distributions in both showed maxima at the same nanoparticle size. The SAXS-measured nanoparticle diameters were slightly larger than the respective diameters measured by TEM. This was because SAXS measures an agglomerate consisting of several particles as one big particle which slightly increased the mean diameter. TEM- and SAXS-measured mean diameters when plotted together showed similar trend in the variation in the size as the laser power was changed which along with extremely similar size distributions for TEM and SAXS validated the application of SAXS for size distribution measurement of the synthesized TiO 2 nanoparticles.

Characterization and antimicrobial activity of silver nanoparticles, biosynthesized using Bacillus species

NASA Astrophysics Data System (ADS)

Ghiuță, I.; Cristea, D.; Croitoru, C.; Kost, J.; Wenkert, R.; Vyrides, I.; Anayiotos, A.; Munteanu, D.

2018-04-01

In this work, the biosynthesis of silver nanoparticles, using AgNO3 as a precursor, by two Bacillus species, namely Bacillus amyloliquefaciens and Bacillus subtillis, is reported. After the synthesis stages, the absorbance of the brown nanoparticle colloidal solutions was assessed by UV-vis spectrophotometry, which showed the peak absorbance values at 418 nm and 414 nm, corresponding to surface plasmon resonance of silver nanoparticles. The EDX, SEM and DLS analyses confirmed the formation of spherical silver nanoparticles with an average diameter smaller than 140 nm. XRD confirmed the presence of face-centered cubic silver crystals, with the highest intensity peak at 2θ = 38.12°, which corresponds to the (111) diffraction planes. The antibacterial activity after 24 h of incubation was observed against gram negative bacteria: Escherichia coli, Pseudomonas aeruginosa, Salmonella, as well as gram positive: Staphylococcus aureus, Streptococcus pyogenes. Furthermore, the antifungal activity was assessed against Candida albicans. The inhibition zone was clearly observed on the plates containing silver nanoparticles, either standalone or in combination with antibiotics, thus showing their potentiating antibacterial effect.

[Preparation and characterization of magnetic nano-particles with radiofrequency-induced hyperthermia for cancer treatment].

PubMed

Fan, Xiangshan; Zhang, Dongsheng; Zheng, Jie; Gu, Ning; Ding, Anwei; Jia, Xiupeng; Qing, Hongyun; Jin, Liqiang; Wan, Meiling; Li, Qunhui

2006-08-01

Mn0.5Zn0.5Fe2O4 nano-particles were prepared by the chemical co-precipitation, their characteristics were observed with transmission electron microscope (TEM), X-ray diffractometer (XRD) and thermal analysis system, and etc. The temperature changes of the nano-particles of Mn0.5Zn0.5Fe2O4 and its magnetic fluid explored in radiofrequency(RF,200 KHz, 4 KW) were measured. The proliferation ratio of L929 cells cultured in soak of Mn0.5Zn0.5Fe2O4 nano-particles were observed. The experiment indicates that the magnetic particles were about 40 nm diameter in average, round, had strong magnetism, and were proved to be consistent with the standard data of chart of XRD. Its magnetic fluid exposed to RF could be heated up to temperature range from 40 degrees C to 51 degrees C due to the amount of the magnetic nano-particles and intensity of the alternating magnetic field. Magnetic nano-particles were found to have no obvious cytotoxicity to L929 cells.

Green synthesis of soya bean sprouts-mediated superparamagnetic Fe 3O 4 nanoparticles

NASA Astrophysics Data System (ADS)

Cai, Yan; Shen, Yuhua; Xie, Anjian; Li, Shikuo; Wang, Xiufang

2010-10-01

Superparamagnetic Fe 3O 4 nanoparticles were first synthesized via soya bean sprouts (SBS) templates under ambient temperature and normal atmosphere. The reaction process was simple, eco-friendly, and convenient to handle. The morphology and crystalline phase of the nanoparticles were determined from scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and X-ray diffraction (XRD) spectra. The effect of SBS template on the formation of Fe 3O 4 nanoparticles was investigated using X-ray photoemission spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FT-IR). The results indicate that spherical Fe 3O 4 nanoparticles with an average diameter of 8 nm simultaneously formed on the epidermal surface and the interior stem wall of SBS. The SBS are responsible for size and morphology control during the whole formation of Fe 3O 4 nanoparticles. In addition, the superconducting quantum interference device (SQUID) results indicate the products are superparamagnetic at room temperature, with blocking temperature ( TB) of 150 K and saturation magnetization of 37.1 emu/g.

Enhancement of antioxidant and antibacterial properties for tannin acid/chitosan/tripolyphosphate nanoparticles filled electrospinning films: Surface modification of sliver nanoparticles.

PubMed

Zhan, Fuchao; Sheng, Feng; Yan, Xiangxing; Zhu, Yingrui; Jin, Weiping; Li, Jing; Li, Bin

2017-11-01

The tannin acid/chitosan/tripolyphosphate nanoparticles were encapsulated in polyvinyl alcohol (PVA)/poly-acrylic acid (PAA) electrospinning films by electrostatic spinning technology. To optimize the prepared condition, properties and morphology of nanoparticles were characterized by dynamic light scattering (DLS) and transmission electron microscope (TEM). The optimized initial concentration of tannin, chitosan and tripolyphosphate solutions were 1, 1, 0.5mg/ml, respectively, with adding proportion for 5:5:1. The average diameter of tannin acid/chitosan/tripolyphosphate nanoparticles was ∼80nm. The electrospinning films showed an excellent water-resistant property with 0.5wt%N,N'-Methylenebisacrylamide (MBA). Due to the antioxidant and antibacterial of tannic acid, the films possessed these properties. The antioxidant and antibacterial of these fibers significantly improved after in situ formation of silver nanoparticles (AgNPs). Electrospun films were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectra (FT-IR), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Copyright © 2017 Elsevier B.V. All rights reserved.

Enhancement of transport of curcumin to brain in mice by poly( n-butylcyanoacrylate) nanoparticle

NASA Astrophysics Data System (ADS)

Sun, Min; Gao, Yan; Guo, Chenyu; Cao, Fengliang; Song, Zhimei; Xi, Yanwei; Yu, Aihua; Li, Aiguo; Zhai, Guangxi

2010-10-01

Curcumin, a widely used coloring agent and spice in food, has a potential in blocking brain tumor formation and curing Alzheimer's disease. Due to the specific properties of blood-brain barrier (BBB), only traces of curcumin were transported across BBB. The aim of the present study was to design and characterize curcumin loaded polybutylcyanoacrylate nanoparticles (PBCN) coated with polysorbate 80, and to evaluate the effect of PBCN as a delivery system on carrying curcumin across BBB. Curcumin loaded nanoparticles were prepared by an anionic polymerization method, and they presented in a core-shell spherical shape under transmission electron microscopy, with an average diameter of 152.0 nm. The average drug loading was 21.1%. Physicochemical status of curcumin in the nanoparticles was confirmed with differential scanning colorimetry and Fourier transform infrared spectroscopy. The in vitro release behavior of drug from the nanoparticles was fitted to a double phase kinetics model. The studies of pharmacokinetic and bio-distribution to brain were conducted in mice after intravenous administration of the nanoparticle formulation at the dose of 5 mg/kg and curcumin solution at the dose of 10 mg/kg via the tail vein. The results showed that in plasma, the area under concentration-time curve (AUC0-∞) for curcumin loaded nanoparticles was greater than that for the control solution, moreover, the mean residence time of curcumin loaded nanoparticles was 14-fold that of the control solution. In brain, AUC0-∞ for curcumin loaded nanoparticles was 2.53-fold that for the control solution. In conclusion, the present study demonstrated that PBCN could enhance the transport of curcumin to brain and have a potential as a delivery system to cross the BBB.

Nanoparticle diffusion in, and microrheology of, the bovine vitreous ex vivo

PubMed Central

Xu, Qingguo; Boylan, Nicholas J.; Suk, Jung Soo; Wang, Ying-Ying; Nance, Elizabeth; Yang, Jeh-Chang; McDonnell, Peter; Cone, Richard; Duh, Elia J.; Hanes, Justin

2013-01-01

Intravitreal injection of biodegradable nanoparticles (NP) holds promise for gene therapy and drug delivery to the back of the eye. In some cases, including gene therapy, NP need to diffuse rapidly from the site of injection in order to reach targeted cell types in the back of the eye, whereas in other cases it may be preferred for the particles to remain at the injection site and slowly release drugs that may then diffuse to the site of action. We studied the movements of polystyrene (PS) nanoparticles of various sizes and surface chemistries in fresh bovine vitreous. PS NP as large as 510 nm rapidly penetrated the vitreous gel when coated with polyethylene glycol (PEG), whereas the movements of NP 1190 nm in diameter or larger were highly restricted regardless of surface chemistry owing to steric obstruction. PS NP coated with primary amine groups (–NH2) possessed positively charged surfaces at the pH of bovine vitreous (pH = 7.2), and were immobilized within the vitreous gel. In comparison, PS NP coated with –COOH (possessing negatively charged surfaces) in the size range of 100–200 nm and at particle concentrations below 0.0025% (w/v) readily diffused through the vitreous meshwork; at higher concentrations (~0.1% w/v), these nanoparticles aggregated within vitreous. Based on the mobility of different sized PS-PEG NP, we estimated the average mesh size of fresh bovine vitreous to be ~550 ± 50 nm. The bovine vitreous behaved as an impermeable elastic barrier to objects sized 1190 nm and larger, but as a highly permeable viscoelastic liquid to non-adhesive objects smaller than 510 nm in diameter. Guided by these studies, we next sought to examine the transport of drug- and DNA-loaded nanoparticles in bovine vitreous. Biodegradable NP with diameter of 227 nm, composed of a poly(lactic-co-glycolic acid) (PLGA)-based core coated with poly(vinyl alcohol) rapidly penetrated vitreous. Rod-shaped, highly-compacted CK30PEG10k/DNA with PEG coating (neutral surface charge; diameter ~60 nm) diffused rapidly within vitreous. These findings will help guide the development of nanoparticle-based therapeutics for the treatment of vision-threatening ocular diseases. PMID:23369761

One-pot green synthesis of zinc oxide nano rice and its application as sonocatalyst for degradation of organic dye and synthesis of 2-benzimidazole derivatives

NASA Astrophysics Data System (ADS)

Paul, Bappi; Vadivel, Sethumathavan; Dhar, Siddhartha Sankar; Debbarma, Shyama; Kumaravel, M.

2017-05-01

In this paper, we report novel and green approach for one-pot biosynthesis of zinc oxide (ZnO) nanoparticles (NPs). Highly stable and hexagonal phase ZnO nanoparticles were synthesized using seeds extract from the tender pods of Parkia roxburghii and characterized by XRD, FT-IR, EDX, TEM, and N2 adsorption-desorption (BET) studies. The present method of synthesis of ZnO NPs is very efficient and cost effective. The powder XRD pattern furnished evidence for the formation of hexagonal close packing structure of ZnO NPs having average crystallite size 25.6 nm. The TEM image reveals rice shapes ZnO NPs are with an average diameter of 40-60 nm. The as-synthesized ZnO NPs has proved to be an excellent sonocatalysts for degradation of organic dye and synthesis of 2-benzimidazole derivatives.

Thermal and ultrasonic influence in the formation of nanometer scale hydroxyapatite bio-ceramic

PubMed Central

Poinern, GJE; Brundavanam, R; Le, X Thi; Djordjevic, S; Prokic, M; Fawcett, D

2011-01-01

Hydroxyapatite (HAP) is a widely used biocompatible ceramic in many biomedical applications and devices. Currently nanometer-scale forms of HAP are being intensely investigated due to their close similarity to the inorganic mineral component of the natural bone matrix. In this study nano-HAP was prepared via a wet precipitation method using Ca(NO3)2 and KH2PO4 as the main reactants and NH4OH as the precipitator under ultrasonic irradiation. The Ca/P ratio was set at 1.67 and the pH was maintained at 9 during the synthesis process. The influence of the thermal treatment was investigated by using two thermal treatment processes to produce ultrafine nano-HAP powders. In the first heat treatment, a conventional radiant tube furnace was used to produce nano-particles with an average size of approximately 30 nm in diameter, while the second thermal treatment used a microwave-based technique to produce particles with an average diameter of 36 nm. The crystalline structure and morphology of all nanoparticle powders produced were investigated using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FT-IR). Both thermal techniques effectively produced ultrafine powders with similar crystalline structure, morphology and particle sizes. PMID:22114473

Preparation and Characterization of Gelatin Nanofibers Containing Silver Nanoparticles

PubMed Central

Jeong, Lim; Park, Won Ho

2014-01-01

Ag nanoparticles (NPs) were synthesized in formic acid aqueous solutions through chemical reduction. Formic acid was used for a reducing agent of Ag precursor and solvent of gelatin. Silver acetate, silver tetrafluoroborate, silver nitrate, and silver phosphate were used as Ag precursors. Ag+ ions were reduced into Ag NPs by formic acid. The formation of Ag NPs was characterized by a UV-Vis spectrophotometer. Ag NPs were quickly generated within a few minutes in silver nitrate (AgNO3)/formic acid solution. As the water content of formic acid aqueous solution increased, more Ag NPs were generated, at a higher rate and with greater size. When gelatin was added to the AgNO3/formic acid solution, the Ag NPs were stabilized, resulting in smaller particles. Moreover, gelatin limits further aggregation of Ag NPs, which were effectively dispersed in solution. The amount of Ag NPs formed increased with increasing concentration of AgNO3 and aging time. Gelatin nanofibers containing Ag NPs were fabricated by electrospinning. The average diameters of gelatin nanofibers were 166.52 ± 32.72 nm, but these decreased with the addition of AgNO3. The average diameters of the Ag NPs in gelatin nanofibers ranged between 13 and 25 nm, which was confirmed by transmission electron microscopy (TEM). PMID:24758929

Small-Sized Mg–Al LDH Nanosheets Supported on Silica Aerogel with Large Pore Channels: Textural Properties and Basic Catalytic Performance after Activation

PubMed Central

Wang, Yusen; Wang, Xiaoxia; Feng, Xiaolan; Ye, Xiao; Fu, Jie

2018-01-01

Layered double hydroxides (LDHs) have been widely used as an important subset of solid base catalysts. However, developing low-cost, small-sized LDH nanoparticles with enhanced surface catalytic sites remains a challenge. In this work, silica aerogel (SA)-supported, small-sized Mg–Al LDH nanosheets were successfully prepared by one-pot coprecipitation of Mg and Al ions in an alkaline suspension of crushed silica aerogel. The supported LDH nanosheets were uniformly dispersed in the SA substrate with the smallest average radial diameter of 19.2 nm and the thinnest average thickness of 3.2 nm, both dimensions being significantly less than those of the vast majority of LDH nanoparticles reported. The SA/LDH composites also showed large pore volume (up to 1.3 cm3·g) and pore diameter (>9 nm), and therefore allow efficient access of reactants to the edge catalytic sites of LDH nanosheets. In a base-catalyzed Henry reaction of benzaldehyde with nitromethane, the SA/LDH catalysts showed high reactant conversions and favorable stability in 6 successive cycles of reactions. The low cost of the SA carrier and LDH precursors, easy preparation method, and excellent catalytic properties make these SA/LDH composites a competitive example of solid-base catalysts. PMID:29462941

Small-Sized Mg-Al LDH Nanosheets Supported on Silica Aerogel with Large Pore Channels: Textural Properties and Basic Catalytic Performance after Activation.

PubMed

Wang, Lijun; Wang, Yusen; Wang, Xiaoxia; Feng, Xiaolan; Ye, Xiao; Fu, Jie

2018-02-16

Layered double hydroxides (LDHs) have been widely used as an important subset of solid base catalysts. However, developing low-cost, small-sized LDH nanoparticles with enhanced surface catalytic sites remains a challenge. In this work, silica aerogel (SA)-supported, small-sized Mg-Al LDH nanosheets were successfully prepared by one-pot coprecipitation of Mg and Al ions in an alkaline suspension of crushed silica aerogel. The supported LDH nanosheets were uniformly dispersed in the SA substrate with the smallest average radial diameter of 19.2 nm and the thinnest average thickness of 3.2 nm, both dimensions being significantly less than those of the vast majority of LDH nanoparticles reported. The SA/LDH composites also showed large pore volume (up to 1.3 cm3·g) and pore diameter (>9 nm), and therefore allow efficient access of reactants to the edge catalytic sites of LDH nanosheets. In a base-catalyzed Henry reaction of benzaldehyde with nitromethane, the SA/LDH catalysts showed high reactant conversions and favorable stability in 6 successive cycles of reactions. The low cost of the SA carrier and LDH precursors, easy preparation method, and excellent catalytic properties make these SA/LDH composites a competitive example of solid-base catalysts.

Stacking fault density and bond orientational order of fcc ruthenium nanoparticles

NASA Astrophysics Data System (ADS)

Seo, Okkyun; Sakata, Osami; Kim, Jae Myung; Hiroi, Satoshi; Song, Chulho; Kumara, Loku Singgappulige Rosantha; Ohara, Koji; Dekura, Shun; Kusada, Kohei; Kobayashi, Hirokazu; Kitagawa, Hiroshi

2017-12-01

We investigated crystal structure deviations of catalytic nanoparticles (NPs) using synchrotron powder X-ray diffraction. The samples were fcc ruthenium (Ru) NPs with diameters of 2.4, 3.5, 3.9, and 5.4 nm. We analyzed average crystal structures by applying the line profile method to a stacking fault model and local crystal structures using bond orientational order (BOO) parameters. The reflection peaks shifted depending on rules that apply to each stacking fault. We evaluated the quantitative stacking faults densities for fcc Ru NPs, and the stacking fault per number of layers was 2-4, which is quite large. Our analysis shows that the fcc Ru 2.4 nm-diameter NPs have a considerably high stacking fault density. The B factor tends to increase with the increasing stacking fault density. A structural parameter that we define from the BOO parameters exhibits a significant difference from the ideal value of the fcc structure. This indicates that the fcc Ru NPs are highly disordered.

Analytical determination of the reducing and stabilization agents present in different Zostera noltii extracts used for the biosynthesis of gold nanoparticles.

PubMed

Zarzuela, Rafael; Luna, Manuel Jesús; Gil, María Luisa Almoraima; Ortega, María Jesús; Palacios-Santander, José María; Naranjo-Rodríguez, Ignacio; Delgado, Juan José; Cubillana-Aguilera, Laura María

2018-02-01

The objective of this work was to ascertain the nature of the components responsible for the reducing and stabilizing properties of Zostera noltii extracts that lead to gold nanoparticle formation using chemical techniques of analysis. In order to achieve this aim, we try the synthesis of AuNPs with three different extracts from plants collected in the Bay of Cádiz (Spain). The n-butanol extract produced the best results. Taking this into account, four fractions were isolated by Sephadex LH-20 column chromatography from this extract and we studied their activity. The chemical study of these fractions led to the isolation of several flavone sulfates and these were identified as the species' responsible for the formation and stabilization of the AuNPs. Flavone sulfates were purified by high performance liquid chromatography and the structures were established by means of spectroscopic methods nuclear magnetic resonance and mass spectroscopy. AuNPs have an average lifetime of about 16weeks. Additionally, the morphology and crystalline phase of the gold nanoparticles were characterized by transmission electron microscopy. The composition of the nanoparticles was evaluated by electron diffraction and energy dispersive X-ray spectroscopy. An 88% of the gold nanoparticles has a diameter in the range 20-35nm, with an average size of 26±2nm. Copyright © 2017 Elsevier B.V. All rights reserved.

Experimental study on the coalescence process of SiO2 supported colloidal Au nanoparticles

NASA Astrophysics Data System (ADS)

Ruffino, F.; Torrisi, V.; Grimaldi, M. G.

2015-11-01

We report on an experimental study of the coalescence-driven grow process of colloidal Au nanoparticles on SiO2 surface. Nanoparticles with 30, 50, 80, 100 nm nominal diameters on a SiO2 substrate were deposited, from solutions, by the drop-casting method. Then, annealing processes, in the 573-1173 K temperature range and 900-3600 s time range, were performed. Using scanning electron microscopy analyses, the temporal evolution of the nanoparticles sizes has been studied. In particular, for all classes of nanoparticles, the experimental-obtained diameters distributions evidenced double-peak shapes (i. e. bimodal distributions): a first peak centered (and unchanged changing the annealing temperature and/or time) at the nominal diameter of the as-deposited nanoparticles, , and a second peak shifting at higher mean diameters, , increasing the annealing temperature and/or time. This observation suggested us a coalescence-driven growth process of a nanoparticles sub-population. As a consequence, the temporal evolution of (for each class of nanoparticles and each annealing temperature), within the well-established particles coalescence theoretical framework, has been analyzed. In particular, by the analyses of the experimental data using relations as prescribed by the theoretical model, a characteristic size-dependent activation energy for the Au nanoparticles coalescence process has been evaluated.

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

Khezri, Khezrollah, E-mail: kh.khezri@ut.ac.ir; Roghani-Mamaqani, Hossein

Graphical abstract: Effect of mesoporous silica nanoparticles (MCM-41) on the activator generated by electron transfer for atom transfer radical polymerization (AGET ATRP) is investigated. Decrement of conversion and number average molecular weight and also increment of polydispersity index (PDI) values are three main results of addition of MCM-41 nanoparticles. Incorporation of MCM-41 nanoparticles in the polystyrene matrix can clearly increase thermal stability and decrease glass transition temperature of the nanocomposites. - Highlights: • Spherical morphology, hexagonal structure, and high surface area with regular pore diameters of the synthesized MCM-41 nanoparticles are examined. • AGET ATRP of styrene in the presencemore » of MCM-41 nanoparticles is performed. • Effect of MCM-41 nanoparticles addition on the polymerization rate, conversion and molecular weights of the products are discussed. • Improvement in thermal stability of the nanocomposites and decreasing T{sub g} values was also observed by incorporation of MCM-41 nanoparticles. - Abstract: Activator generated by electron transfer for atom transfer radical polymerization was employed to synthesize well-defined mesoporous silica nanoparticles/polystyrene composites. Inherent features of spherical mesoporous silica nanoparticles were evaluated by nitrogen adsorption/desorption isotherm, X-ray diffraction and scanning electron microscopy analysis techniques. Conversion and molecular weight evaluations were carried out using gas and size exclusion chromatography respectively. By the addition of only 3 wt% mesoporous silica nanoparticles, conversion decreases from 81 to 58%. Similarly, number average molecular weight decreases from 17,116 to 12,798 g mol{sup −1}. However, polydispersity index (PDI) values increases from 1.24 to 1.58. A peak around 4.1–4.2 ppm at proton nuclear magnetic resonance spectroscopy results clearly confirms the living nature of the polymerization. Thermogravimetric analysis shows that thermal stability of the nanocomposites increases by adding nanoparticles content. Decrease of glass transition temperature is also demonstrated by the addition of 3 wt% of silica nanoparticles according to the differential scanning calorimetry results.« less

Mineralization and optical characterization of copper oxide nanoparticles using a high aspect ratio bio-template

NASA Astrophysics Data System (ADS)

Zaman, Mohammed Shahriar; Haberer, Elaine D.

2014-10-01

Organized chains of copper oxide nanoparticles were synthesized, without palladium (Pd) activation, using the M13 filamentous virus as a biological template. The interaction of Cu precursor ions with the negatively charged viral coat proteins were studied with Fourier transform infrared spectroscopy, transmission electron microscopy, and energy dispersive x-ray spectroscopy. Discrete nanoparticles with an average diameter of 4.5 nm and narrow size distribution were closely spaced along the length of the high aspect ratio templates. The synthesized material was identified as a mixture of cubic Cu2O and monoclinic CuO. UV/Vis absorption measurements were completed and a direct optical band gap of 2.87 eV was determined using Tauc's method. This value was slightly larger than bulk, signaling quantum confinement effects within the templated materials.

Mineralization and optical characterization of copper oxide nanoparticles using a high aspect ratio bio-template

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

Zaman, Mohammed Shahriar; Haberer, Elaine D., E-mail: haberer@ucr.edu; Materials Science and Engineering Program, University of California, Riverside, California 92521

Organized chains of copper oxide nanoparticles were synthesized, without palladium (Pd) activation, using the M13 filamentous virus as a biological template. The interaction of Cu precursor ions with the negatively charged viral coat proteins were studied with Fourier transform infrared spectroscopy, transmission electron microscopy, and energy dispersive x-ray spectroscopy. Discrete nanoparticles with an average diameter of 4.5 nm and narrow size distribution were closely spaced along the length of the high aspect ratio templates. The synthesized material was identified as a mixture of cubic Cu₂O and monoclinic CuO. UV/Vis absorption measurements were completed and a direct optical band gap ofmore » 2.87 eV was determined using Tauc's method. This value was slightly larger than bulk, signaling quantum confinement effects within the templated materials.« less

Delivery of human NKG2D-IL-15 fusion gene by chitosan nanoparticles to enhance antitumor immunity.

PubMed

Yan, Chen; Jie, Leng; Yongqi, Wang; Weiming, Xiao; Juqun, Xi; Yanbing, Ding; Li, Qian; Xingyuan, Pan; Mingchun, Ji; Weijuan, Gong

2015-07-31

Nanoparticles are becoming promising carriers for gene delivery because of their high capacity in gene loading and low cell cytotoxicity. In this study, a chitosan-based nanoparticle encapsulated within a recombinant pcDNA3.1-dsNKG2D-IL-15 plasmid was generated. The fused dsNKG2D-IL-15 gene fragment consisted of double extracellular domains of NKG2D with IL-15 gene at downstream. The average diameter of the gene nanoparticles ranged from 200 nm to 400 nm, with mean zeta potential value of 53.8 ± 6.56 mV. The nanoparticles which were loaded with the dsNKG2D-IL-15 gene were uptaken by tumor cells with low cytotoxicity. Tumor cells pre-transfected by gene nanopartilces stimulated NK and T cells in vitro. Intramuscular injection of gene nanoparticles suppressed tumor growth and prolonged survival of tumor-bearing mice through activation of NK and CD8(+) T cells. Thus, chitosan-based nanoparticle delivery of dsNKG2D-IL-15 gene vaccine can be potentially used for tumor therapy. Copyright © 2015 Elsevier Inc. All rights reserved.

Development of new magnetic nanoparticles: Oligochitosan obtained by γ-rays and -coated Fe3O4 nanoparticles

NASA Astrophysics Data System (ADS)

Le Thi, Thao Nguyen; Nguyen, Thi Hiep; Hoang, Dong Quy; Tran, Tuong, Vi; Nguyen, Ngoc Thuy; Nguyen, Dai Hai

2017-11-01

Oligochitosan (OCS) have been utilized as a potential bioactive material for improving food quality and human health. In this study, superparamagnetic iron oxide (Fe3O4) nanoparticles were originally coated with OCS irradiated by gamma rays for their possible biomedical applications. The formation of Fe3O4@OCS was characterized by Fourier transform infrared (FT-IR), X-ray diffraction patterns (XRD), energy dispersive X-ray spectroscopy (EDS) and thermogravimetric analysis (TGA). In addition, the superparamagnetic properties and sizes and morphologies of Fe3O4 and Fe3O4@OCS nanoparticles were demonstrated by vibrating sample magnetometer (VSM) and transmission electron microscopy (TEM), respectively. These results indicated that Fe3O4@OCS nanoparticles still maintained their superparamagnetic properties after polymeric coating, and were nearly spherical in shape with average diameter of 14.4 ± 0.31 nm, compared with 11.8 ± 0.52 nm of bare Fe3O4 nanoparticles, respectively. As a result, Fe3O4@OCS nanoparticles may serve as a promising platform for the development of new magnetic materials, which could be useful for biomedical applications.

Ni-Fe2O4 nanoparticles as contrast agents for magnetic resonance imaging.

PubMed

Ahmad, Tanveer; Rhee, Ilsu; Hong, Sungwook; Chang, Yongmin; Lee, Jaejun

2011-07-01

Reported herein is the synthesis of a dextran coating on nickel ferrite (Ni-Fe2O4) nanoparticles via chemical coprecipitation. The aqueous solution of the synthesized nanoparticles showed good colloidal stability, and no precipitate was observed 20 months after the synthesis. The coated nanoparticles were found to be cylindrical in shape in the TEM images, and showed a uniform size distribution with an average length and diameter of 17 and 4 nm, respectively. The coated particles were evaluated as potential T1 and T2 contrast agents for MRI. The T1 and T2 relaxations of the hydrogen protons in the water molecules in an aqueous solution of dextran-coated Ni-Fe2O4 nanoparticles were studied. It was found that the T1 relaxivity for the aqueous solution of dextran-coated nanoparticles was slightly greater than that of a commercial Gd-DTPA-BMA contrast agent. The T2 relaxivity, however, was almost twice that of the commercial Gd-DTPA-BMA contrast agent. Animal experimentation also demonstrated that the dextran-coated Ni-Fe2O4 nanoparticles are suitable for use as either T1 or T2 contrast agents in MRI.

Magentite nanoparticle for arsenic remotion.

NASA Astrophysics Data System (ADS)

Viltres, H.; Odio, O. F.; Borja, R.; Aguilera, Y.; Reguera, E.

2017-01-01

Inorganic As (V) and As (III) species are commonly found in groundwater in many countries around the world. It is known that arsenic is highly toxic and carcinogenic, at present exist reports of diverse countries with arsenic concentrations in drinking water higher than those proposed by the World Health Organization (10 μg/L). It has been reported that adsorption strategies using magnetic nanoparticles as magnetite (<20 nm) proved to be very efficient for the removal of arsenic in drinking water. Magnetic nanoparticles (magnetite) were prepared using a co-precipitation method with FeCl3 and FeCl2 as metal source and NaOH aqueous solution as precipitating agent. Magnetite nanoparticles synthesized were put in contact with As2O3 and As2O5 solutions at room temperature to pH 4 and 7. The nanoparticles were characterized by FT-IR, DRX, UV-vis, and XRF. The results showed that synthesized magnetite had an average diameter of 11 nm and a narrow size distribution. The presence of arsenic on magnetite nanoparticles surface was confirmed, which is more remarkable when As (V) is employed. Besides, it is possible to observe that no significant changes in the band gap values after adsorption of arsenic in the nanoparticles.

Resistive switching characteristics of manganese oxide thin film and nanoparticle assembly hybrid devices

NASA Astrophysics Data System (ADS)

Abbas, Haider; Park, Mi Ra; Abbas, Yawar; Hu, Quanli; Kang, Tae Su; Yoon, Tae-Sik; Kang, Chi Jung

2018-06-01

Improved resistive switching characteristics are demonstrated in a hybrid device with Pt/Ti/MnO (thin film)/MnO (nanoparticle)/Pt structure. The hybrid devices of MnO thin film and nanoparticle assembly were fabricated. MnO nanoparticles with an average diameter of ∼30 nm were chemically synthesized and assembled as a monolayer on a Pt bottom electrode. A MnO thin film of ∼40 nm thickness was deposited on the nanoparticle assembly to form the hybrid structure. Resistive switching could be induced by the formation and rupture of conducting filaments in the hybrid oxide layers. The hybrid device exhibited very stable unipolar switching with good endurance and retention characteristics. It showed a larger and stable memory window with a uniform distribution of SET and RESET voltages. Moreover, the conduction mechanisms of ohmic conduction, space-charge-limited conduction, Schottky emission, and Poole–Frenkel emission have been investigated as possible conduction mechanisms for the switching of the devices. Using MnO nanoparticles in the thin film and nanoparticle heterostructures enabled the appropriate control of resistive random access memory (RRAM) devices and markedly improved their memory characteristics.

Gold and Iron Oxide Nanoparticle-Based Ethylcellulose Nanocapsules for Cisplatin Drug Delivery

PubMed Central

Sathish Kumar, Kannaiyan; Jaikumar, Vasudevan

2011-01-01

The present study is aimed at the overall improvement in the efficacy, reduced toxicity and enhancement of therapeutic index of cisplatin. Nanocapsules of cisplatin containing ethylcellulose have been prepared using solvent evaporation technique under ambient conditions. The prepared nanocapsules were used for controlled drug release of anticancer agents with gold and iron oxide nanoparticles. The drug-entrapped nanocapsules were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Fourier transform infrared (FTIR) studies indicated the absence of chemical interactions between the drug, polymer and metal nanoparticles. The drug loaded nanoparticles are spherical in shape and had average diameter in the range of 100-300 nm. Drug release study showed that the acidic media provided a faster release than the phosphate buffer media. These findings were also compared statistically through calculating mean, standard deviation and coefficient of variation for various polymer nanocapsules. However, the drug release for gold nanoparticles/anticancer drug (Au-cis) incorporated ethylcellulose nanocapsules was controlled and slow compared to iron oxide nanoparticles-cisplatin incorporated ethylcellulose nanocapsules. Hence, gold nanoparticles act as good trapping agents which slow down the rate of drug release from nanocapsules. PMID:24250373

Noncrystalline structure of Ni-P nanoparticles prepared by liquid pulse discharge.

PubMed

Tan, Yuanyuan; Yu, Hongying; Wu, Zhonghua; Yang, Bin; Gong, Yu; Yan, Shi; Du, Rong; Chen, Zhongjun; Sun, Dongbai

2015-03-01

Noncrystalline nickel phosphide (Ni-P) nanoparticles have drawn great attention due to their high potential as catalysts. However, the structure of noncrystalline Ni-P nanoparticles is still unknown, which may shed light on explaining the catalysis mechanism of the Ni-P nanoparticles. In this paper, noncrystalline Ni-P nanoparticles were synthesized. Their morphology, particle size, element contents, local atomic structures, as well as the catalysis in the thermal decomposition of ammonium perchlorate were studied. The results demonstrate that the as-prepared Ni-P nanoparticles are spherical with an average diameter of about 13.5 nm. The Ni and P contents are, respectively, 78.15% and 21.85%. The noncrystalline nature of the as-prepared Ni-P nanoparticles can be attributed to cross-linkage between P-doping f.c.c.-like Ni centers and Ni3P-like P centers. The locally ordered Ni centers and P centers are the nuclei sites, which can explain well the origin of initial nuclei to form the crystalline phases after high-temperature annealing. The starting temperature of high-temperature decomposition of ammonium perchlorate was found having a significant decrease in the presence of the noncrystalline Ni-P nanoparticles. Therefore, the as-prepared noncrystalline Ni-P nanoparticles can be used as a potential catalyst in the thermal decomposition of ammonium perchlorate.

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

Yan, Chen; Jie, Leng; Yongqi, Wang

Nanoparticles are becoming promising carriers for gene delivery because of their high capacity in gene loading and low cell cytotoxicity. In this study, a chitosan-based nanoparticle encapsulated within a recombinant pcDNA3.1-dsNKG2D-IL-15 plasmid was generated. The fused dsNKG2D-IL-15 gene fragment consisted of double extracellular domains of NKG2D with IL-15 gene at downstream. The average diameter of the gene nanoparticles ranged from 200 nm to 400 nm, with mean zeta potential value of 53.8 ± 6.56 mV. The nanoparticles which were loaded with the dsNKG2D-IL-15 gene were uptaken by tumor cells with low cytotoxicity. Tumor cells pre-transfected by gene nanopartilces stimulated NK and T cells in vitro. Intramuscularmore » injection of gene nanoparticles suppressed tumor growth and prolonged survival of tumor-bearing mice through activation of NK and CD8{sup +} T cells. Thus, chitosan-based nanoparticle delivery of dsNKG2D-IL-15 gene vaccine can be potentially used for tumor therapy. - Highlights: • Generation of a nanoparticle for delivery of dsNKG2D-IL-15 gene. • Characterization of the gene nanoparticle. • Antitumor activity mediated by the gene nanoparticle.« less

Quercetin conjugated with silica nanoparticles inhibits tumor growth in MCF-7 breast cancer cell lines.

PubMed

Aghapour, Fahimeh; Moghadamnia, Ali Akbar; Nicolini, Andrea; Kani, Seydeh Narges Mousavi; Barari, Ladan; Morakabati, Payam; Rezazadeh, Leyla; Kazemi, Sohrab

2018-06-12

Quercetin is a plant polyphenol from the flavonoid group that plays a fundamental role in controlling homeostasis due to its potent antioxidant properties. However, quercetin has extremely low water solubility, which is a major challenge in drug absorption. In this study, we described a simple method for the synthesis of quercetin nanoparticles. The quercetin nanoparticles had an average diameter of 82 nm and prominent yellow emission under UV irradiation. Therefore, we used an in vitro model treated with quercetin and quercetin nanoparticles to investigate the effects of quercetin nanoparticles on MCF-7 breast cancer cell line. MCF-7 cells were cultured with different concentrations (1-100 μM) of quercetin nanoparticles at the 24th, 48th and 72 nd hours, and cell cycle and apoptosis assays were detected by flow cytometry (FCM). In this study, we found that quercetin nanoparticles (1-100 μM) could significantly reduce cell vitality, growth rate and colony formation of MCF-7 cells. Quercetin nanoparticles can inhibit cell growth by blocking the cell cycle and promoting apoptosis in MCF-7 cells more than quercetin. As a result, quercetin nanoparticles may be useful therapy or prevention on breast cancer. Copyright © 2018 Elsevier Inc. All rights reserved.

Green synthesis of silver nanoparticles using methanolic root extracts of Diospyros paniculata and their antimicrobial activities.

PubMed

Rao, N Hanumanta; N, Lakshmidevi; Pammi, S V N; Kollu, Pratap; S, Ganapaty; P, Lakshmi

2016-05-01

Since the discovery and subsequent widespread use of antibiotics, a variety of bacterial species of human and animal origin have developed numerous mechanisms that render bacteria resistant to some, and in certain cases to nearly all antibiotics, thereby limiting the treatment options and compromising effective therapy. In the present study, the green synthesis of nanoparticles is carried out by the reduction of silver acetate in the presence of crude methanolic root extracts of Diospyros paniculata, a member of family Ebenaceae. The UV-Vis absorption spectrum of the biologically reduced reaction mixture showed the surface plasmon peak at 428 nm, a characteristic peak of silver nanoparticles. X-ray diffraction (XRD) analysis confirmed the face-centered cubic crystalline structure of metallic silver. The average diameter of Ag NPs is about 17 nm from Transmission Electron Microscopy (TEM) which is in good agreement with the average crystallite size (19 nm) calculated from XRD analysis. Further the study has been extended to the antimicrobial activity against test pathogenic Gram (+), Gram (-) bacterial and fungal strains. The biologically synthesized silver nanoparticles showed promising activity against all the tested pathogenic strains and the activity has been enhanced with the increased dose levels. Copyright © 2016 Elsevier B.V. All rights reserved.

Visible-light-assisted SLCs template synthesis of sea anemone-like Pd/PANI nanocomposites with high electrocatalytic activity for methane oxidation in acidic medium

NASA Astrophysics Data System (ADS)

Tan, De-Xin; Wang, Yan-Li

2018-03-01

Sea anemone-like palladium (Pd)/polyaniline (PANI) nanocomposites were synthesized via visible-light-assisted swollen liquid crystals (SLCs) template method. The resulting samples were characterized by transmission electron microscopy (TEM), selected area electron diffraction (SAED), energy dispersive spectrometer (EDS), x-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), ultraviolet-visible (UV–vis) absorption spectroscopy and Fourier transform infrared (FT-IR) spectroscopy, respectively. The electrocatalytic properties of Pd/PANI nanocomposites modified glass carbon electrode (GCE) for methane oxidation were investigated by cycle voltammetry (CV) and chronoamperometry. Those dispersed sea anemone-like Pd/PANI nanocomposites had an average diameter of 320 nm. The obtained Pd nanoparticles with an average diameter of about 45 nm were uniformly distributed in PANI matrix. Sea anemone-like Pd/PANI nanocomposites exhibited excellent electrocatalytic activity and stability for oxidation of methane (CH4).

Low toxic maghemite nanoparticles for theranostic applications.

PubMed

Kuchma, Elena A; Zolotukhin, Peter V; Belanova, Anna A; Soldatov, Mikhail A; Lastovina, Tatiana A; Kubrin, Stanislav P; Nikolsky, Anatoliy V; Mirmikova, Lidia I; Soldatov, Alexander V

2017-01-01

Iron oxide nanoparticles have numerous and versatile biological properties, ranging from direct and immediate biochemical effects to prolonged influences on tissues. Most applications have strict requirements with respect to the chemical and physical properties of such agents. Therefore, developing rational design methods of synthesis of iron oxide nanoparticles remains of vital importance in nanobiomedicine. Low toxic superparamagnetic iron oxide nanoparticles (SPIONs) for theranostic applications in oncology having spherical shape and maghemite structure were produced using the fast microwave synthesis technique and were fully characterized by several complementary methods (transmission electron microscopy [TEM], X-ray diffraction [XRD], dynamic light scattering [DLS], X-ray photoelectron spectroscopy [XPS], X-ray absorption near edge structure [XANES], Mossbauer spectroscopy, and HeLa cells toxicity testing). TEM showed that the majority of the obtained nanoparticles were almost spherical and did not exceed 20 nm in diameter. The averaged DLS hydrodynamic size was found to be ~33 nm, while that of nanocrystallites estimated by XRD waŝ16 nm. Both XRD and XPS studies evidenced the maghemite (γ-Fe 2 O 3 ) atomic and electronic structure of the synthesized nanoparticles. The XANES data analysis demonstrated the structure of the nanoparticles being similar to that of macroscopic maghemite. The Mossbauer spectroscopy revealed the γ-Fe 2 O 3 phase of the nanoparticles and vibration magnetometry study showed that reactive oxygen species in HeLa cells are generated both in the cytoplasm and the nucleus. Quasispherical Fe 3+ SPIONs having the maghemite structure with the average size of 16 nm obtained by using the fast microwave synthesis technique are expected to be of great value for theranostic applications in oncology and multimodal anticancer therapy.

Structure and optical properties of ZnO with silver nanoparticles

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

Lyadov, N. M., E-mail: nik061287@mail.ru; Gumarov, A. I.; Kashapov, R. N.

Textured nanocrystalline ZnO thin films are synthesized by ion beam assisted deposition. According to X-ray diffraction data, the crystallite size is ∼25 nm. Thin (∼15 nm) ZnO layers containing Ag nanoparticles are formed in a thin surface region of the films by the implantation of Ag ions with an energy of 30 keV and a dose in the range (0.25–1) × 10{sup 17} ion/cm{sup 2}. The structure and optical properties of the layers are studied. Histograms of the size distribution of Ag nanoparticles are obtained. The average size of the Ag nanoparticles varies from 0.5 to 1.5–2 nm depending onmore » the Ag-ion implantation dose. The optical transmittance of the samples in the visible and ultraviolet regions increases, as the implantation dose is increased. The spectra of the absorption coefficient of the implanted films are calculated in the context of the (absorbing film)/(transparent substrate) model. It is found that the main changes in the optical-density spectra occur in the region of ∼380 nm, in which the major contribution to absorption is made by Ag nanoparticles smaller than 0.75 nm in diameter. In this spectral region, absorption gradually decreases, as the Ag-ion irradiation dose is increased. This is attributed to an increase in the average size of the Ag nanoparticles. It is established that the broad surface-plasmon-resonance absorption bands typical of nanocomposite ZnO films with Ag nanoparticles synthesized by ion implantation are defined by the fact that the size of the nanoparticles formed does not exceed 1.5–2 nm.« less

Low toxic maghemite nanoparticles for theranostic applications

PubMed Central

Zolotukhin, Peter V; Belanova, Anna A; Soldatov, Mikhail A; Lastovina, Tatiana A; Kubrin, Stanislav P; Nikolsky, Anatoliy V; Mirmikova, Lidia I

2017-01-01

Background Iron oxide nanoparticles have numerous and versatile biological properties, ranging from direct and immediate biochemical effects to prolonged influences on tissues. Most applications have strict requirements with respect to the chemical and physical properties of such agents. Therefore, developing rational design methods of synthesis of iron oxide nanoparticles remains of vital importance in nanobiomedicine. Methods Low toxic superparamagnetic iron oxide nanoparticles (SPIONs) for theranostic applications in oncology having spherical shape and maghemite structure were produced using the fast microwave synthesis technique and were fully characterized by several complementary methods (transmission electron microscopy [TEM], X-ray diffraction [XRD], dynamic light scattering [DLS], X-ray photoelectron spectroscopy [XPS], X-ray absorption near edge structure [XANES], Mossbauer spectroscopy, and HeLa cells toxicity testing). Results TEM showed that the majority of the obtained nanoparticles were almost spherical and did not exceed 20 nm in diameter. The averaged DLS hydrodynamic size was found to be ~33 nm, while that of nanocrystallites estimated by XRD waŝ16 nm. Both XRD and XPS studies evidenced the maghemite (γ-Fe2O3) atomic and electronic structure of the synthesized nanoparticles. The XANES data analysis demonstrated the structure of the nanoparticles being similar to that of macroscopic maghemite. The Mossbauer spectroscopy revealed the γ-Fe2O3 phase of the nanoparticles and vibration magnetometry study showed that reactive oxygen species in HeLa cells are generated both in the cytoplasm and the nucleus. Conclusion Quasispherical Fe3+ SPIONs having the maghemite structure with the average size of 16 nm obtained by using the fast microwave synthesis technique are expected to be of great value for theranostic applications in oncology and multimodal anticancer therapy. PMID:28919740

Synthesis of Metal Nanoparticles and Metal Fluoride Nanoparticles from Metal Amidinate Precursors in 1‐Butyl‐3‐Methylimidazolium Ionic Liquids and Propylene Carbonate

PubMed Central

Schütte, Kai; Barthel, Juri; Endres, Manuel; Siebels, Marvin; Smarsly, Bernd M.; Yue, Junpei

2016-01-01

Abstract Decomposition of transition‐metal amidinates [M{MeC(NiPr)2}n] [M(AMD)n; M=MnII, FeII, CoII, NiII, n=2; CuI, n=1) induced by microwave heating in the ionic liquids (ILs) 1‐butyl‐3‐methylimidazolium tetrafluoroborate ([BMIm][BF4]), 1‐butyl‐3‐methylimidazolium hexafluorophosphate ([BMIm][PF6]), 1‐butyl‐3‐methylimidazolium trifluoromethanesulfonate (triflate) ([BMIm][TfO]), and 1‐butyl‐3‐methylimidazolium tosylate ([BMIm][Tos]) or in propylene carbonate (PC) gives transition‐metal nanoparticles (M‐NPs) in non‐fluorous media (e.g. [BMIm][Tos] and PC) or metal fluoride nanoparticles (MF2‐NPs) for M=Mn, Fe, and Co in [BMIm][BF4]. FeF2‐NPs can be prepared upon Fe(AMD)2 decomposition in [BMIm][BF4], [BMIm][PF6], and [BMIm][TfO]. The nanoparticles are stable in the absence of capping ligands (surfactants) for more than 6 weeks. The crystalline phases of the metal or metal fluoride synthesized in [BMIm][BF4] were identified by powder X‐ray diffraction (PXRD) to exclusively Ni‐ and Cu‐NPs or to solely MF2‐NPs for M=Mn, Fe, and Co. The size and size dispersion of the nanoparticles were determined by transmission electron microscopy (TEM) to an average diameter of 2(±2) to 14(±4) nm for the M‐NPs, except for the Cu‐NPs in PC, which were 51(±8) nm. The MF2‐NPs from [BMIm][BF4] were 15(±4) to 65(±18) nm. The average diameter from TEM is in fair agreement with the size evaluated from PXRD with the Scherrer equation. The characterization was complemented by energy‐dispersive X‐ray spectroscopy (EDX). Electrochemical investigations of the CoF2‐NPs as cathode materials for lithium‐ion batteries were simply evaluated by galvanostatic charge/discharge profiles, and the results indicated that the reversible capacity of the CoF2‐NPs was much lower than the theoretical value, which may have originated from the complex conversion reaction mechanism and residue on the surface of the nanoparticles. PMID:28168159

Light-induced switching of 1,3-diazabicyclo-[3.1.0]hex-3-enes on gold nanoparticles

NASA Astrophysics Data System (ADS)

Mahmoodi, Nosrat O.; Ahmadi, Narges Khatoon; Ghavidast, Atefeh

2018-05-01

The fabrication of hybrid nanoassemblies involving sulfure-modified photochromic derivatives (SMPDs) on the gold nanoparticles (AuNPs) was carried out to investigate the influence of AuNPs surface plasmons on the SMPDs photoisomerization. The size of the AuNPs obtained was <30 nm in average diameter. Upon irradiation by alternating UV and Vis light, a reversible photochemical isomerization along with bathochromic shift in the absorption band takes place on the surface of the AuNPs in analogy with free SMPDs in solutions. Furthermore, in some cases a significant quenching of photochromic reactivity was observed due to the excited energy transfer from the photochromic molecules to the AuNPs core.

High potential of Mn-doped ZnS nanoparticles with different dopant concentrations as novel MRI contrast agents: synthesis and in vitro relaxivity studies

NASA Astrophysics Data System (ADS)

Jahanbin, Tania; Gaceur, Meriem; Gros-Dagnac, Hélène; Benderbous, Soraya; Merah, Souad Ammar

2015-06-01

Over several decades, metal-doped quantum dots (QDs) with core-shell structure have been studied as dual probes: fluorescence and magnetic resonance imaging (MRI) probes (Dixit et al., Mater Lett 63(30):2669-2671, 2009). However, metal-doped nanoparticles, in which the majority of metal ions are close to the surface, can affect their efficacy as MRI contrast agents (CAs). In this context, herein the high potential of synthesized Mn-doped ZnS QDs via polyol method as imaging probe is demonstrated. The mean diameters of QDs were measured via transmission electron microscopy (TEM) and X-ray diffraction (XRD). Optical and magnetic properties of MnZnS nanoparticles were characterized using fluorescence spectroscopy and super quanducting interference devices magnetometer and electron paramagnetic resonance system, respectively. T1- and T2-weighted images of nanoparticles in aqueous solution were acquired from spin-echo sequences at 3 T. From TEM images and XRD spectra of the prepared nanoparticles, it is observed that the average diameter of particles does not significantly change with Mn dopant content ( 1.6-1.9 nm). All three samples exhibit broad blue emission under UV light excitation. According to the MRI studies, MnZnS nanoparticles generate strong T1 contrast enhancement (bright T1-weighted images) at the low concentration (<0.1 mM). The MnZnS nanoparticles exhibit the high longitudinal ( r 1) relaxivity that increases from 20.34 to 75.5 mM-1 s-1 with the Mn dopant contents varying between 10 and 30 %. Strong signal intensity on T1-weighted images and high r 1 with {r2 }/{r_{1 }} ≈ 1 can demonstrate the high potential of the synthesized Mn:ZnS nanoparticles, which can serve as an effective T1 CA.

In-situ precipitation of ultra-stable nano-magnetite slurry

NASA Astrophysics Data System (ADS)

Ramimoghadam, Donya; Bagheri, Samira; Hamid, Sharifah Bee Abd

2015-04-01

In this contribution, we prepared water-based magnetic fluids of iron oxide nanoparticles using an in-situ precipitation method. The effect of dodecanoic acid addition as a surfactant on the physico-chemical and magnetic properties of iron oxide nanoparticles was investigated as well. The quantity of the surfactant was varied between 3 and 5 g. Raman spectroscopy and X-ray diffraction (XRD) were utilized to confirm the presence of spinel phase magnetites (Fe3O4). Dynamic light scattering (DLS) and transmission electron microscopy (TEM) were used to characterize the resulting magnetic nanoparticles' size and morphology. The results showed polydispersed hexagonal nanoparticles (average diameter of ca. 70 nm) as a result of the protocol. Moreover, the pH-dependent stability of the samples confirms that magnetite nanofluids were highly stable in the wide range of pH, from 4-12. The optimal amount of dodecanoic acid to produce ultra-stable nano-magnetite slurry with the highest saturation magnetization of 8.6 emu g-1 was determined to be 4.5 g.

Preparation and Properties of Electrospun Poly (Vinyl Pyrrolidone)/Cellulose Nanocrystal/Silver Nanoparticle Composite Fibers

PubMed Central

Huang, Siwei; Zhou, Ling; Li, Mei-Chun; Wu, Qinglin; Kojima, Yoichi; Zhou, Dingguo

2016-01-01

Poly (vinyl pyrrolidone) (PVP)/cellulose nanocrystal (CNC)/silver nanoparticle composite fibers were prepared via electrospinning using N,N′-dimethylformamide (DMF) as a solvent. Rheology, morphology, thermal properties, mechanical properties, and antimicrobial activity of nanocomposites were characterized as a function of material composition. The PVP/CNC/Ag electrospun suspensions exhibited higher conductivity and better rheological properties compared with those of the pure PVP solution. The average diameter of the PVP electrospun fibers decreased with the increase in the amount of CNCs and Ag nanoparticles. Thermal stability of electrospun composite fibers was decreased with the addition of CNCs. The CNCs help increase the composite tensile strength, while the elongation at break decreased. The composite fibers included Ag nanoparticles showed improved antimicrobial activity against both the Gram-negative bacterium Escherichia coli (E. coli) and the Gram-positive bacterium Staphylococcus aureus (S. aureus). The enhanced strength and antimicrobial performances of PVP/CNC/Ag electrospun composite fibers make the mat material an attractive candidate for application in the biomedical field. PMID:28773644

Palladium and platinum-based nanoparticle functional sensor layers for selective H2 sensing

DOEpatents

Ohodnicki, Jr., Paul R.; Baltrus, John P.; Brown, Thomas D.

2017-07-04

The disclosure relates to a plasmon resonance-based method for H.sub.2 sensing in a gas stream utilizing a hydrogen sensing material. The hydrogen sensing material is comprises Pd-based or Pt-based nanoparticles having an average nanoparticle diameter of less than about 100 nanometers dispersed in an inert matrix having a bandgap greater than or equal to 5 eV, and an oxygen ion conductivity less than approximately 10.sup.-7 S/cm at a temperature of 700.degree. C. Exemplary inert matrix materials include SiO.sub.2, Al.sub.2O.sub.3, and Si.sub.3N.sub.4 as well as modifications to modify the effective refractive indices through combinations and/or doping of such materials. The hydrogen sensing material utilized in the method of this disclosure may be prepared using means known in the art for the production of nanoparticles dispersed within a supporting matrix including sol-gel based wet chemistry techniques, impregnation techniques, implantation techniques, sputtering techniques, and others.

Cell viability study of thermo-responsive core-shell superparamagnetic nanoparticles for multimodal cancer therapy

NASA Astrophysics Data System (ADS)

Shah, Saqlain A.; Majeed, A.; Shafique, M. A.; Rashid, K.; Awan, Saif-Ullah

2014-02-01

This is a vital extension of our previously published work. Thermo-responsive copolymer coated superparamagnetic MnFe2O4 nanoparticles are tested for cell viability and affinity on HeLa carcinoma cells under different conditions. Nanoparticles were loaded with anticancer drug doxorubicin. Composite nanoparticles of average diameter 45 nm were of core-shell structure having magnetic core of about 18 nm. Magnetic hyperthermia effects on cell viability and drug delivery were studied by exposing the cell suspension to high frequency magnetic field, and living cells were quantified using MTT method. There was almost absence of drug release at 37 °C. Drug was released at temperatures above lower critical solution temperature (LCST) by magnetic heating. LCST of the thermo-responsive copolymer was observed to be around 39 °C. Below this temperature, copolymer was hydrophilic and swelled. But above LCST, copolymer could become hydrophobic, expel water and drug and shrink in volume. Combination of hyperthermia and drug delivery effectively treated cancer cells.

Thermal stability and electrochemical properties of PVP-protected Ru nanoparticles synthesized at room temperature

NASA Astrophysics Data System (ADS)

Kumar, Manish; Devi, Pooja; Shivling, V. D.

2017-08-01

Stable ruthenium nanoparticles (RuNPs) have been synthesized by the chemical reduction of ruthenium trichloride trihydrate (RuCl3 · 3H2O) using sodium borohydride (NaBH4) as a reductant and polyvinylpyrrolidone (PVP) as a protecting agent in the aqueous medium at room temperature. The nanoparticles thus prepared were characterized by their morphology and structural analysis from transmission electron microscopy (TEM), X-ray powder diffraction (XRD), UV-vis spectroscopy, Fourier transformation infrared and thermogravimetric analysis (TGA) techniques. The TEM image suggested a homogeneous distribution of PVP-protected RuNPs having a small average diameter of 2-4 nm with a chain-like network structure. The XRD pattern also confirmed that a crystallite size is around 2 nm of PVP-protected RuNPs having a single broad peak. The thermal stability studied using TGA, indicated good stability and the electrochemical properties of these nanoparticles revealed that saturation current increases for PVP-protected RuNPs/GC.

Temperature and composition dependent density of states extracted using overlapping large polaron tunnelling model in MnxCo1-xFe2O4 (x=0.25, 0.5, 0.75) nanoparticles

NASA Astrophysics Data System (ADS)

Jamil, Arifa; Afsar, M. F.; Sher, F.; Rafiq, M. A.

2017-03-01

We report detailed ac electrical and structural characterization of manganese cobalt ferrite nanoparticles, prepared by coprecipitation technique. X-ray diffraction (XRD) confirmed single-phase cubic spinel structure of the nanoparticles. Tetrahedral (A) and octahedral (B) group complexes were present in the spinel lattice as determined by Fourier Transform Infrared Spectroscopy (FTIR). Scanning Electron Microscope (SEM) images revealed presence of spherical shape nanoparticles having an average diameter 50-80 nm. Composition, temperature and frequency dependent ac electrical study of prepared nanoparticles interpreted the role of cationic distribution between A and B sites. Overlapping large polaron tunnelling (OLPT) conduction mechanism was observed from 290 to 200 K. Frequency exponent s was fitted theoretically using OLPT model. High values of Density of States (DOS) of the order of 1022-1024 eV-1 cm-3 were extracted from ac conductivity for different compositions. We found that DOS was dependent on distribution of cations in the tunnel-type cavities along the a and b axis.

Effect of Fe{sub 3}O{sub 4} nanoparticles on positive streamer propagation in transformer oil

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

Lv, Yuzhen, E-mail: yzlv@ncepu.edu.cn; School of Energy, Power and Mechanical Engineering, North China Electric Power University, Beijing, 102206; Wang, Qi

Fe{sub 3}O{sub 4} nanoparticles with an average diameter of 10 nm were prepared and used to modify streamer characteristic of transformer oil. It was found that positive streamer propagation velocity in transformer oil-based Fe{sub 3}O{sub 4} nanofluid is greatly reduced by 51% in comparison with that in pure oil. The evolution of streamer shape is also dramatically affected by the presence of nanoparticles, changing from a tree-like shape with sharp branches in pure oil to a bush-like structure with thicker and denser branches in nanofluid. The TSC results reveal that the modification of Fe{sub 3}O{sub 4} nanoparticle can greatly increasemore » the density of shallow trap and change space charge distribution in nanofluid by converting fast electrons into slow electrons via trapping and de-trapping process in shallow traps. These negative space charges induced by nanoparticles greatly alleviate the electric field distortion in front of the positive streamer tip and significantly hinder the propagation of positive streamer.« less

The bipyridine adducts of N-phenyldithiocarbamato complexes of Zn(II) and Cd(II); synthesis, spectral, thermal decomposition studies and use as precursors for ZnS and CdS nanoparticles.

PubMed

Onwudiwe, Damian C; Strydom, Christien A

2015-01-25

Bipyridine adducts of N-phenyldithiocarbamato complexes, [ML(1)2L(2)] (M=Cd(II), Zn(II); L(1)=N-phenyldithiocarbamate, L(2)=2,2' bipyridine), have been synthesized and characterised. The decomposition of these complexes to metal sulphides has been investigated by thermogravimetric analysis (TGA). The complexes were used as single-source precursors to synthesize MS (M=Zn, Cd) nanoparticles (NPs) passivated by hexadecyl amine (HDA). The growth of the nanoparticles was carried out at two different temperatures: 180 and 220 °C, and the optical and structural properties of the nanoparticles were studied using UV-Vis spectroscopy, photoluminescence spectroscopy (PL), transmission emission microscopy (TEM) and powdered X-ray diffraction (p-XRD). Nanoparticles, whose average diameters are 2.90 and 3.54 nm for ZnS, and 8.96 and 9.76 nm for CdS grown at 180 and 220 °C respectively, were obtained. Copyright © 2014 Elsevier B.V. All rights reserved.

Hydrothermal synthesis of superparamagnetic Fe{sub 3}O{sub 4} nanoparticles with ionic liquids as stabilizer

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

Liu, Xiao-Di, E-mail: liuxiaodiny@126.com; Chen, Hao; Liu, Shan-Shan

2015-02-15

Highlights: • Superparamagnetic Fe{sub 3}O{sub 4} nanoparticles with good dispersity have been synthesized via hydrothermal method. • Ionic liquid [C{sub 16}mim]Cl acts as stabilizer for the Fe{sub 3}O{sub 4} nanoparticles. • Fe{sub 3}O{sub 4} nanoparticles have a saturation magnetization of 67.69 emu/g at 300 K. - Abstract: Superparamagnetic Fe{sub 3}O{sub 4} nanoparticles have been successfully synthesized under hydrothermal condition with the assistant of ionic liquid 1-hexadecyl-3-methylimidazolium chloride ([C{sub 16}mim]Cl). The structure and morphology of the sample have been investigated by X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), transmission electron microscopy (TEM), and high-resolution TEM (HRTEM), and the results indicate thatmore » the as-synthesized inverse spinel Fe{sub 3}O{sub 4} nanoparticles have an average diameter of about 10 nm and exhibit relatively good dispersity. More importantly, it is found that [C{sub 16}mim]Cl acts as stabilizer for the Fe{sub 3}O{sub 4} nanoparticles by adsorbing on the particles surfaces to prevent the agglomeration. In addition, the obtained superparamagnetic Fe{sub 3}O{sub 4} nanoparticles have a saturation magnetization of 67.69 emu/g at 300 K.« less

Induction of apoptosis in cancer cells by NiZn ferrite nanoparticles through mitochondrial cytochrome C release.

PubMed

Al-Qubaisi, Mothanna Sadiq; Rasedee, Abdullah; Flaifel, Moayad Husein; Ahmad, Sahrim Hj; Hussein-Al-Ali, Samer; Hussein, Mohd Zobir; Zainal, Zulkarnain; Alhassan, Fatah H; Taufiq-Yap, Yun H; Eid, Eltayeb E M; Arbab, Ismail Adam; Al-Asbahi, Bandar A; Webster, Thomas J; El Zowalaty, Mohamed Ezzat

2013-01-01

The long-term objective of the present study was to determine the ability of NiZn ferrite nanoparticles to kill cancer cells. NiZn ferrite nanoparticle suspensions were found to have an average hydrodynamic diameter, polydispersity index, and zeta potential of 254.2 ± 29.8 nm, 0.524 ± 0.013, and -60 ± 14 mV, respectively. We showed that NiZn ferrite nanoparticles had selective toxicity towards MCF-7, HepG2, and HT29 cells, with a lesser effect on normal MCF 10A cells. The quantity of Bcl-2, Bax, p53, and cytochrome C in the cell lines mentioned above was determined by colorimetric methods in order to clarify the mechanism of action of NiZn ferrite nanoparticles in the killing of cancer cells. Our results indicate that NiZn ferrite nanoparticles promote apoptosis in cancer cells via caspase-3 and caspase-9, downregulation of Bcl-2, and upregulation of Bax and p53, with cytochrome C translocation. There was a concomitant collapse of the mitochondrial membrane potential in these cancer cells when treated with NiZn ferrite nanoparticles. This study shows that NiZn ferrite nanoparticles induce glutathione depletion in cancer cells, which results in increased production of reactive oxygen species and eventually, death of cancer cells.

Seed mediated synthesis of highly mono-dispersed gold nanoparticles in the presence of hydroquinone

NASA Astrophysics Data System (ADS)

Kumar, Dhiraj; Mutreja, Isha; Sykes, Peter

2016-09-01

Gold nanoparticles (AuNPs) are being studied for several biomedical applications, including drug delivery, biomedical imaging, contrast agents and tumor targeting. The synthesis of nanoparticles with a narrow size distribution is critical for these applications. We report the synthesis of highly mono-dispersed AuNPs by a seed mediated approach, in the presence of tri-sodium citrate and hydroquinone (HQ). AuNPs with an average size of 18 nm were used for the synthesis of highly mono-dispersed nanocrystals of an average size 40 nm, 60 nm, 80 nm and ˜100 nm; but the protocol is not limited to these sizes. The colloidal gold was subjected to UV-vis absorbance spectroscopy, showing a red shift in lambda max wavelength, peaks at 518.47 nm, 526.37 nm, 535.73 nm, 546.03 nm and 556.50 nm for AuNPs seed (18 nm), 40 nm, 60 nm, 80 nm and ˜100 nm respectively. The analysis was consistent with dynamic light scattering and electron microscopy. Hydrodynamic diameters measured were 17.6 nm, 40.8 nm, 59.8 nm, 74.1 nm, and 91.4 nm (size by dynamic light scattering—volume %); with an average poly dispersity index value of 0.088, suggesting mono-dispersity in the size distribution, which was also confirmed by transmission electron microscopy analysis. The advantage of a seed mediated approach is a multi-step growth of nanoparticle size that enables us to control the number of nanoparticles in the suspension, for size ranging from 24.5 nm to 95.8 nm. In addition, the HQ-based synthesis of colloidal nanocrystals allowed control of the particle size and size distribution by tailoring either the number of seeds, amount of gold precursor or reducing agent (HQ) in the final reaction mixture.

The Fate of Polyol-Made ZnO and CdS Nanoparticles in Seine River Water (Paris, France).

PubMed

da Rocha, Alice; Sivry, Yann; Gelabert, Alexandre; Beji, Zyed; Benedetti, Marc F; Menguy, Nicolas; Brayner, Roberta

2015-05-01

This study aims to characterize nanoparticles with different compositions and structures as well as seeing their evolutions over time in a natural environment such as Seine river water (Paris, France). Face centered cubic (fcc) and hexagonal (hcp) CdS as well as hexagonal (hcp) ZnO nanoparticles were synthesized by the Polyol method. CdS nanoparticles (i) cfc structure: are agglomerated, present 100 nm length with heterogeneous diameter and 10 m2 g(-1) specific surface area (S(g)) from Brunauer Emett and Teller (BET) measurements; (ii) hcp structure: 20 nm and S(g) = 67 m2 g(-1). ZnO hcp nanoparticles presents 50 nm length and 15 nm diameter and S(g) = 54 m2 g(-1). These results are in agreement with X-ray diffraction (XRD), and small angle X-ray scattering (SAXs). After 48 h interaction with Seine river water, cryo-TEM analysis showed that ZnO nanoparticles form spherical agglomerates with 300 nm diameter; CdS nanoparticles (fcc) are agglomerated presenting large diameters (> 500 nm); and CdS nanoparticles (hcp) are not agglomerated and present the same characteristics of the starting material. After 168h of contact with Seine river water, CdS (fcc) presents only 14% of dissolution, CdS (hcp) presents both 60% dissolution and 30% reprecipitation in a cadmium carbonate form and finally almost 90% of ZnO nanoparticles are dissolved.

Parameters optimization for synthesis of Al-doped ZnO nanoparticles by laser ablation in water

NASA Astrophysics Data System (ADS)

Krstulović, Nikša; Salamon, Krešimir; Budimlija, Ognjen; Kovač, Janez; Dasović, Jasna; Umek, Polona; Capan, Ivana

2018-05-01

Al-doped ZnO crystalline colloidal nanoparticles were synthesized by a laser ablation of ZnO:Al2O3 in MilliQ water. Experiments were performed systematically by changing the number of applied laser pulses and laser output energy with the aim to affect the nanoparticle size, composition (Al/Zn ratio) and characteristics (band-gap, crystallinity). Distinctly, set of nanoparticle syntheses was performed in deionized water for comparison. SEM investigation of colloidal nanoparticles revealed that the formed nanoparticles are 30 nm thick discs with average diameters ranging from 450 to 510 nm. It was found that craters in the target formed during the laser ablation influence the size of synthesized colloidal nanoparticles. This is explained by efficient nanoparticle growth through diffusion process which take place in spatially restricted volume of the target crater. When laser ablation takes place in deionized water the synthesized nanoparticles have a mesh-like structure with sparse concentration of disc-like nanoparticles. Al/Zn ratio and band-gap energy of nanoparticles are highly influenced by the number and output energy of applied laser pulses. In addition, the procedure how to calculate the concentration of colloidal nanoparticles synthesized by laser ablation in liquids is proposed. The Al-doped ZnO colloidal nanoparticles properties were obtained using different techniques like scanning electron microscopy, optical microscopy, energy-dispersive X-ray spectroscopy, grazing-incidence X-ray diffraction, photoabsorption, photoluminescence and X-ray photoelectron spectroscopy.

Effects of para-substituents of styrene derivatives on their chemical reactivity on platinum nanoparticle surfaces.

PubMed

Hu, Peiguang; Chen, Limei; Deming, Christopher P; Lu, Jia-En; Bonny, Lewis W; Chen, Shaowei

2016-06-09

Stable platinum nanoparticles were successfully prepared by the self-assembly of para-substituted styrene derivatives onto the platinum surfaces as a result of platinum-catalyzed dehydrogenation and transformation of the vinyl groups to the acetylene ones, forming platinum-vinylidene/-acetylide interfacial bonds. Transmission electron microscopic measurements showed that the nanoparticles were well dispersed without apparent aggregation, suggesting sufficient protection of the nanoparticles by the organic capping ligands, and the average core diameter was estimated to be 2.0 ± 0.3 nm, 1.3 ± 0.2 nm, and 1.1 ± 0.2 nm for the nanoparticles capped with 4-tert-butylstyrene, 4-methoxystyrene, and 4-(trifluoromethyl)styrene, respectively, as a result of the decreasing rate of dehydrogenation with the increasing Taft (polar) constant of the para-substituents. Importantly, the resulting nanoparticles exhibited unique photoluminescence, where an increase of the Hammett constant of the para-substituents corresponded to a blue-shift of the photoluminescence emission, suggesting an enlargement of the HOMO-LUMO band gap of the nanoparticle-bound acetylene moieties. Furthermore, the resulting nanoparticles exhibited apparent electrocatalytic activity towards oxygen reduction in acidic media, with the best performance among the series of samples observed with the 4-tert-butylstyrene-capped nanoparticles due to an optimal combination of the nanoparticle core size and ligand effects on the bonding interactions between platinum and oxygen species.

Radiosensitization effect of folate-conjugated gold nanoparticles on HeLa cancer cells under orthovoltage superficial radiotherapy techniques

NASA Astrophysics Data System (ADS)

Khoshgard, Karim; Hashemi, Bijan; Arbabi, Azim; Javad Rasaee, Mohammad; Soleimani, Masoud

2014-05-01

Due to the high atomic number of gold nanoparticles (GNPs), they are known as new radiosensitizer agents for enhancing the efficiency of superficial radiotherapy techniques by increasing the dose absorbed in tumor cells wherein they can be accumulated selectively. The aim of this study was to compare the effect of various common low energy levels of orthovoltage x-rays and megavoltage γ-rays (Co-60) on enhancing the therapeutic efficiency of HeLa cancer cells in the presence of conjugated folate and non-conjugated (pegylated) GNPs. To achieve this, GNPs with an average diameter of 52 nm were synthesized and conjugated to folic acid molecules. Pegylated GNPs with an average diameter of 47 nm were also synthesized and used as non-conjugated folate GNPs. Cytotoxicity assay of the synthesized folate-conjugated and pegylated GNPs was performed using different levels of nanoparticle concentration incubated with HeLa cells for 24 h. The radiosensitizing effect of both the conjugated and pegylated GNPs on the cells at a concentration of 50 µM was compared using MTT as well as clonogenic assays after exposing them to 2 Gy ionizing radiation produced by an orthovoltage x-ray machine at four different kVps and γ-rays of a Co-60 unit. Significant differences were noted among various irradiated groups with and without the folate conjugation, with an average dose enhancement factor (DEF) of 1.64 ± 0.05 and 1.35 ± 0.05 for the folate-conjugated and pegylated GNPs, respectively. The maximum DEF was obtained with the 180 kVp x-ray beam for both of the GNPs. Folate-conjugated GNPs can significantly enhance the cell killing potential of orthovoltage x-ray energies (especially at 180 kVp) in folate receptor-expressing cancer cells, such as HeLa, in superficial radiotherapy techniques.

Radiosensitization effect of folate-conjugated gold nanoparticles on HeLa cancer cells under orthovoltage superficial radiotherapy techniques.

PubMed

Khoshgard, Karim; Hashemi, Bijan; Arbabi, Azim; Rasaee, Mohammad Javad; Soleimani, Masoud

2014-05-07

Due to the high atomic number of gold nanoparticles (GNPs), they are known as new radiosensitizer agents for enhancing the efficiency of superficial radiotherapy techniques by increasing the dose absorbed in tumor cells wherein they can be accumulated selectively. The aim of this study was to compare the effect of various common low energy levels of orthovoltage x-rays and megavoltage γ-rays (Co-60) on enhancing the therapeutic efficiency of HeLa cancer cells in the presence of conjugated folate and non-conjugated (pegylated) GNPs. To achieve this, GNPs with an average diameter of 52 nm were synthesized and conjugated to folic acid molecules. Pegylated GNPs with an average diameter of 47 nm were also synthesized and used as non-conjugated folate GNPs. Cytotoxicity assay of the synthesized folate-conjugated and pegylated GNPs was performed using different levels of nanoparticle concentration incubated with HeLa cells for 24 h. The radiosensitizing effect of both the conjugated and pegylated GNPs on the cells at a concentration of 50 µM was compared using MTT as well as clonogenic assays after exposing them to 2 Gy ionizing radiation produced by an orthovoltage x-ray machine at four different kVps and γ-rays of a Co-60 unit. Significant differences were noted among various irradiated groups with and without the folate conjugation, with an average dose enhancement factor (DEF) of 1.64 ± 0.05 and 1.35 ± 0.05 for the folate-conjugated and pegylated GNPs, respectively. The maximum DEF was obtained with the 180 kVp x-ray beam for both of the GNPs. Folate-conjugated GNPs can significantly enhance the cell killing potential of orthovoltage x-ray energies (especially at 180 kVp) in folate receptor-expressing cancer cells, such as HeLa, in superficial radiotherapy techniques.

Opening the black box: imaging nanoparticle transport with MRI

NASA Astrophysics Data System (ADS)

Phoenix, V.; Holmes, W. M.

2009-12-01

While most renown for its use in medicine, magnetic resonance imaging (MRI) has tremendous potential in the study of environmental processes. Its ability to non-invasively image inside materials that are opaque to other imaging methods (in particular light based techniques) is a particular strength. MRI has already been used, for example, to study fluid flow in rocks and image mass transport and biogeochemical processes in biofilms [1-4]. Here, we report of the use of MRI to image nanoparticle transport through porous geologic media (in this case packed gravel columns). Packed column experiments are key to understanding nanoparticulate transport in porous geologic media. Whilst highly informative, the data obtained can be a bulk average of a complex and heterogeneous array of interactions within the column. Natural environmental systems are often complex, displaying heterogeneity in geometry, hydrodynamics, geochemistry and microbiology throughout. MRI enables us to quantify better how this heterogeneity may influence nanoparticle transport and fate by enabling us to look inside the column and image the movement of nanoparticles within. To make the nanoparticle readily visible to MRI, it is labelled with a paramagnetic tag (commonly gadolinium). Indeed, a wide variety of off-the-shelf paramagnetically tagged nanoparticles and macromolecules are available, each with different properties enabling us to explore the impact of particle charge, size etc on their transport behaviour. In this preliminary study, packed columns of quartz or marble based gravels (approx 5 mm diameter) were first imaged to check their suitability for MR imaging. This was done as geologic material can contain sufficiently high concentrations of ferro- and paramagnetic ions to induce unwanted artefacts in the MR image. All gravels imaged (Rose quartz, Creswick quartz gravel and Ben Deulin white marble) produced minimal or no artefacts. A solution of the nanoparticle GadoCELLTrack (BioPAL), was prepared and connected to a 30 mm diameter flow cell containing rose quartz. GadoCELLTrack is a 30 nm diameter, neutrally charged gadolinium colloid. MR images were collected as the nanoparticle solution was pumped through the flow cell. These images were calibrated to provide fully quantitative maps of nanoparticle concentration at regular time intervals throughout the column. Such data can be used to help develop predictive models of nanoparticulate transport. [1] Holmes WM, Packer KJ (2003) Magnetic Resonance Imaging 21,389-391 [2] Seymour JD et al., (2004) Journal of Magnetic Resonance 167, 322-327 [3] McLean JS et al., (2008) ISME, 2, 121-131 [4] Phoenix et al., (2008) Applied and Environmental Microbiology, 74, 4934-4943

MnFe{sub 2}O{sub 4} as a gas sensor towards SO{sub 2} and NO{sub 2} gases

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

Rathore, Deepshikha, E-mail: deep.nano@gmail.com; Mitra, Supratim

2016-05-06

The chemical co-precipitation method was used to synthesize MnFe{sub 2}O{sub 4} nanoparticles. Single cubic phase formation of nanoparticles was confirmed by X-ray diffraction technique. The average particle size of MnFe{sub 2}O{sub 4} nanoparticles was found to be 10.7 nm using Scherrer formula. The ultrafine powder of MnFe{sub 2}O{sub 4} nanoparticles was pressed to design pellet of 10 mm diameter and 1mm thickness. Copper electrodes have been deposited on the surface of pellet using silver paste in the form of capacitor. Fabricated gas sensing device of MnFe{sub 2}O{sub 4} nanoparticles was tested towards SO{sub 2} and NO{sub 2} gases. Cole-Cole plot of MnFe{submore » 2}O{sub 4} was investigated with the help of electrochemical workstation. The performance of the sensors including sensitivity, response and recovery time was also determined. It was observed that the MnFe{sub 2}O{sub 4} nanoparticles are more sensible for NO{sub 2} gas as compared to SO{sub 2} gas.« less

The controlled release of tilmicosin from silica nanoparticles.

PubMed

Song, Meirong; Li, Yanyan; Fai, Cailing; Cui, Shumin; Cui, Baoan

2011-06-01

The aim of this study was to use silica nanoparticles as the carrier for controlled release of tilmicosin. Tilmicosin was selected as a drug model molecule because it has a lengthy elimination half-life and a high concentration in milk after subcutaneous administration. Three samples of tilmicosin-loaded silica nanoparticles were prepared with different drug-loading weight. The drug-loading weight in three samples, as measured by thermal gravimetric analysis, was 29%, 42%, and 64%, respectively. With increased drug-loading weight, the average diameter of the drug-loaded silica nanoparticles was increased from 13.4 to 25.7 nm, and the zeta potential changed from-30.62 to-6.78 mV, indicating that the stability of the drug-loaded particles in the aqueous solution decreases as drug-loading weight increases. In vitro release studies in phosphate-buffered saline showed the sample with 29% drug loading had a slow and sustained drug release, reaching 44% after 72 h. The release rate rose with increased drug-loading weight; therefore, the release of tilmicosin from silica nanoparticles was well-controlled by adjusting the drug loading. Finally, kinetics analysis suggested that drug released from silica nanoparticles was mainly a diffusion-controlled process.

Hydrothermally synthesized PEGylated calcium phosphate nanoparticles incorporating Gd-DTPA for contrast enhanced MRI diagnosis of solid tumors.

PubMed

Mi, Peng; Kokuryo, Daisuke; Cabral, Horacio; Kumagai, Michiaki; Nomoto, Takahiro; Aoki, Ichio; Terada, Yasuko; Kishimura, Akihiro; Nishiyama, Nobuhiro; Kataoka, Kazunori

2014-01-28

Organic-inorganic hybrid nanoparticles with calcium phosphate (CaP) core and PEGylated shell were developed to incorporate magnetic resonance imaging (MRI) contrast agent diethylenetriaminepentaacetic acid gadolinium (III) (Gd-DTPA) for noninvasive diagnosis of solid tumors. A two-step preparation method was applied to elaborate hybrid nanoparticles with a z-average hydrodynamic diameter about 80nm, neutral surface ξ-potential and high colloidal stability in physiological environments by self-assembly of poly(ethylene glycol)-b-poly(aspartic acid) block copolymer, Gd-DTPA, and CaP in aqueous solution, followed with hydrothermal treatment. Incorporation into the hybrid nanoparticles allowed Gd-DTPA to show significant enhanced retention ratio in blood circulation, leading to high accumulation in tumor positions due to enhanced permeability and retention (EPR) effect. Moreover, Gd-DTPA revealed above 6 times increase of relaxivity in the nanoparticle system compared to free form, and eventually, selective and elevated contrast enhancements in the tumor positions were observed. These results indicate the high potential of Gd-DTPA-loaded PEGylated CaP nanoparticles as a novel contrast agent for noninvasive cancer diagnosis. Copyright © 2013 Elsevier B.V. All rights reserved.

Synthesis and characterization of bracelet-like magnetic nanorings consisting of Ag-Fe3O4 bi-component nanoparticles.

PubMed

Zhou, Shuai; Chen, Qianwang

2011-09-14

Stable bracelet-like magnetic nanorings, formed by Ag-Fe(3)O(4) nanoparticles with an average size around 40 nm, have been successfully prepared in large scale by means of reducing Ag(+) and Fe(3+) simultaneously under mild conditions. In the reaction, tiny grains of silver are used as seeds to prompt small Fe(3)O(4) nanoparticles to grow larger, which is essential to enhance the magnetic dipole-dipole interactions, while only superparamagnetic Fe(3)O(4) nanoparticles (about 10 nm in size) can be obtained in the absence of Ag seeds. The XRD, TEM, SAED and the EDS line scan data reveal that these nanoparticles are in the core-shell structure. These magnetic Ag-Fe(3)O(4) nanoparticles assembled into nanorings by magnetic dipole-dipole interactions with a diameter of 100-200 nm. The saturation magnetization of the nanorings is 39.5 emu g(-1) at room temperature. The MRI images indicate that these kind of nanorings have the potential application in diagnostics as a T(2) MRI contrast agent. This journal is © The Royal Society of Chemistry 2011

Characteristic of nanoparticles generated from different nano-powders by using different dispersion methods

NASA Astrophysics Data System (ADS)

Tsai, Chuen-Jinn; Lin, Guan-Yu; Liu, Chun-Nan; He, Chi-En; Chen, Chun-Wan

2012-03-01

A standard rotating drum with a modified sampling train (RD), a vortex shaker (VS), and a SSPD (small-scale powder disperser) were used to investigate the emission characteristics of nano-powders, including nano-titanium dioxide (nano-TiO2, primary diameter: 21 nm), nano-zinc oxide (nano-ZnO, primary diameter: 30-50 nm), and nano-silicon dioxide (nano-SiO2, primary diameter: 10-30 nm). A TSI SMPS (scanning mobility particle sizer), a TSI APS (aerodynamic particle sizer), and a MSP MOUDI (micro-orifice uniform deposit impactor) were used to measure the number and mass distributions of generated particles. Significant differences in specific number and mass concentration or distributions were found among different methods and nano-powders with the most specific number and mass concentration and the smallest particles being generated by the most energetic SSPD, followed by VS and RD. Near uni-modal number or mass distributions were observed for the SSPD while bi-modal number or mass distributions existed for nano-powders except nano-SiO2 which also exhibited bimodal mass distributions. The 30-min average results showed that the mass median aerodynamic diameter (MMAD) and number median diameter (NMD) of the SSPD ranged 1.1-2.1 μm and 166-261 nm, respectively, for all three nano-powders, which were smaller than those of the VS (MMAD: 3.3-6.0 μm and NMD: 156-462 nm), and the RD (MMAD: 5.2-11.2 μm and NMD: 198-479 nm). For nano-particles (electric mobility diameter < 100 nm), specific mass concentrations were nearly negligible for all three nano-powders and test methods. Specific number concentrations of nano-particles were low for the RD tester but were elevated when more energetic VS and SSPD testers were used. The quantitative size and concentration data obtained in this study is useful to elucidate the field emission and personal exposure data in the future provided that particle loss in the generation system is carefully assessed.

Bulk Preparation of Holey Graphene via Controlled Catalytic Oxidation

NASA Technical Reports Server (NTRS)

Connell, John (Inventor); Watson, Kent (Inventor); Ghose, Sayata (Inventor); Lin, Yi (Inventor)

2015-01-01

A scalable method allows preparation of bulk quantities of holey carbon allotropes with holes ranging from a few to over 100 nm in diameter. Carbon oxidation catalyst nanoparticles are first deposited onto a carbon allotrope surface in a facile, controllable, and solvent-free process. The catalyst-loaded carbons are then subjected to thermal treatment in air. The carbons in contact with the carbon oxidation catalyst nanoparticles are selectively oxidized into gaseous byproducts such as CO or CO.sub.2, leaving the surface with holes. The catalyst is then removed via refluxing in diluted nitric acid to obtain the final holey carbon allotropes. The average size of the holes correlates strongly with the size of the catalyst nanoparticles and is controlled by adjusting the catalyst precursor concentration. The temperature and time of the air oxidation step, and the catalyst removal treatment conditions, strongly affect the morphology of the holes.

Naturally inspired SERS substrates fabricated by photocatalytically depositing silver nanoparticles on cicada wings

PubMed Central

2014-01-01

Densely stacked Ag nanoparticles with an average diameter of 199 nm were effectively deposited on TiO2-coated cicada wings (Ag/TiO2-coated wings) from a water-ethanol solution of AgNO3 using ultraviolet light irradiation at room temperature. It was seen that the surfaces of bare cicada wings contained nanopillar array structures. In the optical absorption spectra of the Ag/TiO2-coated wings, the absorption peak due to the localized surface plasmon resonance (LSPR) of Ag nanoparticles was observed at 440 nm. Strong Surface-enhanced Raman scattering (SERS) signals of Rhodamine 6G adsorbed on the Ag/TiO2-coated wings were clearly observed using the 514.5-nm line of an Ar+ laser. The Ag/TiO2-coated wings can be a promising candidate for naturally inspired SERS substrates. PMID:24959110

Essential oils nanoformulations for stored-product pest control - characterization and biological properties.

PubMed

Werdin González, Jorge Omar; Gutiérrez, María Mercedes; Ferrero, Adriana Alicia; Fernández Band, Beatriz

2014-04-01

The lethal and sublethal activity of poly(ethylene glycol) (PEG) nanoparticles containing essential oils (EO), also the physicochemical characterization, were determined against Tribolium castaneum and Rhizopertha dominica. The 10% ratio EO-PEG nanoparticles showed an average diameter<235 nm (PDI<0.280) and a loading efficacy>75%; after 6 month of storage their size did not change significantly and the amount of the EOs decreased 25%, approximately. Furthermore, during this period, no chemical derivates were observed. The EOs nanoparticles produced a notable increase of the residual contact toxicity apparently due to the slow and persistent release of the active terpenes. In addition, the nanoformulation enhanced the EO contact toxicity and altered the nutritional physiology of both stored product pest. The results indicated that these novel systems could be used in integrated pest management program for T. castaneum and R. dominica control. Copyright © 2013 Elsevier Ltd. All rights reserved.

Naturally inspired SERS substrates fabricated by photocatalytically depositing silver nanoparticles on cicada wings

NASA Astrophysics Data System (ADS)

Tanahashi, Ichiro; Harada, Yoshiyuki

2014-06-01

Densely stacked Ag nanoparticles with an average diameter of 199 nm were effectively deposited on TiO2-coated cicada wings (Ag/TiO2-coated wings) from a water-ethanol solution of AgNO3 using ultraviolet light irradiation at room temperature. It was seen that the surfaces of bare cicada wings contained nanopillar array structures. In the optical absorption spectra of the Ag/TiO2-coated wings, the absorption peak due to the localized surface plasmon resonance (LSPR) of Ag nanoparticles was observed at 440 nm. Strong Surface-enhanced Raman scattering (SERS) signals of Rhodamine 6G adsorbed on the Ag/TiO2-coated wings were clearly observed using the 514.5-nm line of an Ar+ laser. The Ag/TiO2-coated wings can be a promising candidate for naturally inspired SERS substrates.

Plasma-assisted synthesis and study of structural and magnetic properties of Fe/C core shell

NASA Astrophysics Data System (ADS)

Shinde, K. P.; Ranot, M.; Choi, C. J.; Kim, H. S.; Chung, K. C.

2017-07-01

Pure and carbon-encapsulated iron nanoparticles with an average diameter of 25 nm were synthesized by using the DC plasma arc discharge method. Fe core nanoparticles were encapsulated with carbon layer, which is acting as protection layer against both oxidation and chemical reaction. The morphology and the Fe/C core/shell structure of the nanoparticles were studied by using field emission scanning electron microscopy and transmission electron microscopy. The x-ray diffraction study showed that the α-Fe phase exists with γ-Fe as an impurity. The studied samples have been interrelated with the variation of saturation magnetization, remanent magnetization and coercive field with the amount of carbon coating. The pure α-Fe sample shows saturation magnetization = 172 emu/g, and coercive field = 150 Oe, on the other hand few layer carbon coated α-Fe sample shows saturation magnetization =169 emu/g with higher coercive field 398 Oe.

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

NASA Astrophysics Data System (ADS)

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

2018-05-01

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

Thermoelectric properties of conducting polyaniline/BaTiO3 nanoparticle composite films

NASA Astrophysics Data System (ADS)

Anno, H.; Yamaguchi, K.; Nakabayashi, T.; Kurokawa, H.; Akagi, F.; Hojo, M.; Toshima, N.

2011-05-01

Conducting polyaniline (PANI)/BaTiO3 nanoparticle composite films with different molar ratio values R=1, 5, 10, and 100 have been prepared on a quartz substrate by casting the m-cresol solution of PANI, (±)-10-camphorsulfonic acid (CSA) and BaTiO3 nanoparticle with an average diameter of about 20 nm. The CSA-doped PANI/BaTiO3 composite films were characterized by x-ray diffraction, Fourier transform infrared spectroscopy, and UV-Vis transmission spectroscopy. The Seebeck coefficient and the electrical conductivity of the films with different R values, together with CSA-doped PANI films, were measured in the temperature range from room temperature to ~400 K. The relation between the Seebeck coefficient and the electrical conductivity in the composite films are discussed from a comparison of them with those of CSA-doped PANI films and other PANI composite films.

Targeted delivery of polyoxometalate nanocomposites.

PubMed

Geisberger, Georg; Paulus, Susann; Gyenge, Emina Besic; Maake, Caroline; Patzke, Greta R

2011-10-04

Polyoxometalate/carboxymethyl chitosan nanocomposites with an average diameter of 130 nm are synthesized and labeled with fluorescein isothiocyanate (FITC) for a combined drug-carrier and cellular-monitoring approach. [Eu(β(2) -SiW(11) O(39) )(2) ](13-) /CMC nanospheres as a representative example do not display cytotoxicity for POM concentrations up to 2 mg mL(-1) . Cellular uptake of fluoresecently labelled {EuSiW(11) O(39) }/FITC-CMC nanoparticles is monitored with confocal laser scanning microscopy. Nanoparticle uptake occurs after incubation times of around 1 h and no cyctotoxic effects are observed upon prolonged treatment. The preferential location of the POM/CMC nanocomposites in the perinuclear region is furthermore verified with transmission electron microscopy investigations on unlabeled nanoparticles. Therefore, this approach is a promising dual strategy for the safe cellular transfer and monitoring of bioactive POMs. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Long-circulating Janus nanoparticles made by electrohydrodynamic co-jetting for systemic drug delivery applications.

PubMed

Rahmani, Sahar; Villa, Carlos H; Dishman, Acacia F; Grabowski, Marika E; Pan, Daniel C; Durmaz, Hakan; Misra, Asish C; Colón-Meléndez, Laura; Solomon, Michael J; Muzykantov, Vladimir R; Lahann, Joerg

2015-01-01

Nanoparticles with controlled physical properties have been widely used for controlled release applications. In addition to shape, the anisotropic nature of the particles can be an important design criterion to ensure selective surface modification or independent release of combinations of drugs. Electrohydrodynamic (EHD) co-jetting is used for the fabrication of uniform anisotropic nanoparticles with individual compartments and initial physicochemical and biological characterization is reported. EHD co-jetting is used to create nanoparticles, which are characterized at each stage with scanning electron microscopy (SEM), structured illumination microscopy (SIM), dynamic light scattering (DLS) and nanoparticle tracking analysis (NTA). Surface immobilization techniques are used to incorporate polyethylene glycol (PEG) and I(125) radiolabels into the nanoparticles. Particles are injected in mice and the particle distribution after 1, 4 and 24 hours is assessed. Nanoparticles with an average diameter of 105.7 nm are prepared by EHD co-jetting. The particles contain functional chemical groups for further surface modification and radiolabeling. The density of PEG molecules attached to the surface of nanoparticles is determined to range between 0.02 and 6.04 ligands per square nanometer. A significant fraction of the nanoparticles (1.2% injected dose per mass of organ) circulates in the blood after 24 h. EHD co-jetting is a versatile method for the fabrication of nanoparticles for drug delivery. Circulation of the nanoparticles for 24 h is a pre-requisite for subsequent studies to explore defined targeting of the nanoparticles to a specific anatomic site.

Terahertz pulse generation from metal nanoparticle ink

NASA Astrophysics Data System (ADS)

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

2016-11-01

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

Gold nanoparticle uptake in whole cells in liquid examined by environmental scanning electron microscopy.

PubMed

Peckys, Diana B; de Jonge, Niels

2014-02-01

The size of gold nanoparticles (AuNPs) can influence various aspects of their cellular uptake. Light microscopy is not capable of resolving most AuNPs, while electron microscopy (EM) is not practically capable of acquiring the necessary statistical data from many cells and the results may suffer from various artifacts. Here, we demonstrate the use of a fast EM method for obtaining high-resolution data from a much larger population of cells than is usually feasible with conventional EM. A549 (human lung carcinoma) cells were subjected to uptake protocols with 10, 15, or 30 nm diameter AuNPs with adsorbed serum proteins. After 20 min, 24 h, or 45 h, the cells were fixed and imaged in whole in a thin layer of liquid water with environmental scanning electron microscopy equipped with a scanning transmission electron microscopy detector. The fast preparation and imaging of 145 whole cells in liquid allowed collection of nanoscale data within an exceptionally small amount of time of ~80 h. Analysis of 1,041 AuNP-filled vesicles showed that the long-term AuNP storing lysosomes increased their average size by 80 nm when AuNPs with 30 nm diameter were uptaken, compared to lysosomes of cells incubated with AuNPs of 10 and 15 nm diameter.

Microbial synthesis of Flower-shaped gold nanoparticles.

PubMed

Singh, Priyanka; Kim, Yeon Ju; Wang, Chao; Mathiyalagan, Ramya; Yang, Deok Chun

2016-09-01

The shape of nanoparticles has been recognized as an important attribute that determines their applicability in various fields. The flower shape (F-shape) has been considered and is being focused on, because of its enhanced properties when compared to the properties of the spherical shape. The present study proposed the microbial synthesis of F-shaped gold nanoparticles within 48 h using the Bhargavaea indica DC1 strain. The F-shaped gold nanoparticles were synthesized extracellularly by the reduction of auric acid in the culture supernatant of B. indica DC1. The shape, size, purity, and crystalline nature of F-shaped gold nanoparticles were revealed by various instrumental techniques including UV-Vis, FE-TEM, EDX, elemental mapping, XRD, and DLS. The UV-Vis absorbance showed a maximum peak at 536 nm. FE-TEM revealed the F-shaped structure of nanoparticles. The EDX peak obtained at 2.3 keV indicated the purity. The peaks obtained on XRD analysis corresponded to the crystalline nature of the gold nanoparticles. In addition, the results of elemental mapping indicated the maximum distribution of gold elements in the nanoproduct obtained. Particle size analysis revealed that the average diameter of the F-shaped gold nanoparticles was 106 nm, with a polydispersity index (PDI) of 0.178. Thus, the methodology developed for the synthesis of F-shaped gold nanoparticles is completely green and economical.

Chitosan-based biocatalytic nanoparticles for pollutant removal from wastewater.

PubMed

Alarcón-Payán, Dulce A; Koyani, Rina D; Vazquez-Duhalt, Rafael

2017-05-01

Chitosan, a renewable biopolymer has the prospective applications in different fields due to its gelation capacity. Nanoconfiguration of chitosan through ionotropic gelation to encapsulate enzymatic activity offers numerous potential applications. In the present study, the preparation and characterization of chitosan nanoparticles loaded with versatile peroxidase are reported. Their performance in bioremediation process and the resistance enhancement against natural microbial biodegradation were studied. The average diameter of enzymatic nanoparticles was 120nm and showed a high enzyme loading capacity. The kinetic parameters of nanoparticles exhibited a slightly lower catalytic activity (k cat ), similar affinity constant (Km) for hydrogen peroxide and higher Km value for the phenolic compound when compared with the free enzyme. The enzymatic nanoparticles showed higher thermostability and the same pH activity profile than those from free enzyme. Ten phenolic compounds, including pesticides, halogenated compounds, endocrine disruptors and antibacterials were transformed by the enzymatic nanoparticles. The transformation rate was lower than those obtained with free enzyme suggesting mass transfer limitations. But very importantly, the enzymatic nanoparticles showed a significant increase of the operational stability in real conditions of wastewater treatment process. Moreover, chemical modification of nanoparticles with different aldehydes still enhanced the operational stability of nanoparticulated enzymes. This enhancement of stability in real conditions and the potential use of biocatalytic nanoparticles in bioremediation processes are discussed. Copyright © 2017 Elsevier Inc. All rights reserved.

Imaging of Biological Cells Using Luminescent Silver Nanoparticles

NASA Astrophysics Data System (ADS)

Kravets, Vira; Almemar, Zamavang; Jiang, Ke; Culhane, Kyle; Machado, Rosa; Hagen, Guy; Kotko, Andriy; Dmytruk, Igor; Spendier, Kathrin; Pinchuk, Anatoliy

2016-01-01

The application of luminescent silver nanoparticles as imaging agents for neural stem and rat basophilic leukemia cells was demonstrated. The experimental size dependence of the extinction and emission spectra for silver nanoparticles were also studied. The nanoparticles were functionalized with fluorescent glycine dimers. Spectral position of the resonance extinction and photoluminescence emission for particles with average diameters ranging from 9 to 32 nm were examined. As the particle size increased, the spectral peaks for both extinction and the intrinsic emission of silver nanoparticles shifted to the red end of the spectrum. The intrinsic photoluminescence of the particles was orders of magnitude weaker and was spectrally separated from the photoluminescence of the glycine dimer ligands. The spectral position of the ligand emission was independent of the particle size; however, the quantum yield of the nanoparticle-ligand system was size-dependent. This was attributed to the enhancement of the ligand's emission caused by the local electric field strength's dependence on the particle size. The maximum quantum yield determined for the nanoparticle-ligand complex was (5.2 ± 0.1) %. The nanoparticles were able to penetrate cell membranes of rat basophilic leukemia and neural stem cells fixed with paraformaldehyde. Additionally, toxicity studies were performed. It was found that towards rat basophilic leukemia cells, luminescent silver nanoparticles had a toxic effect in the silver atom concentration range of 10-100 μM.

Lactoferrin conjugated iron oxide nanoparticles for targeting brain glioma cells in magnetic particle imaging

NASA Astrophysics Data System (ADS)

Tomitaka, Asahi; Arami, Hamed; Gandhi, Sonu; Krishnan, Kannan M.

2015-10-01

Magnetic Particle Imaging (MPI) is a new real-time imaging modality, which promises high tracer mass sensitivity and spatial resolution directly generated from iron oxide nanoparticles. In this study, monodisperse iron oxide nanoparticles with median core diameters ranging from 14 to 26 nm were synthesized and their surface was conjugated with lactoferrin to convert them into brain glioma targeting agents. The conjugation was confirmed with the increase of the hydrodynamic diameters, change of zeta potential, and Bradford assay. Magnetic particle spectrometry (MPS), performed to evaluate the MPI performance of these nanoparticles, showed no change in signal after lactoferrin conjugation to nanoparticles for all core diameters, suggesting that the MPI signal is dominated by Néel relaxation and thus independent of hydrodynamic size difference or presence of coating molecules before and after conjugations. For this range of core sizes (14-26 nm), both MPS signal intensity and spatial resolution improved with increasing core diameter of nanoparticles. The lactoferrin conjugated iron oxide nanoparticles (Lf-IONPs) showed specific cellular internalization into C6 cells with a 5-fold increase in MPS signal compared to IONPs without lactoferrin, both after 24 h incubation. These results suggest that Lf-IONPs can be used as tracers for targeted brain glioma imaging using MPI.

Polymer Stabilized Nanosuspensions Formed via Flash Nanoprecipitation: Nanoparticle Formation, Formulation, and Stability

NASA Astrophysics Data System (ADS)

Zhu, ZhengXi

Nanoparticles loaded with hydrophobic components (e.g., active pharmaceutical ingredients, medical diagnostic agents, nutritional or personal care chemicals, catalysts, dyes/pigments, and substances with exceptional magnetic/optical/electronic/thermal properties) have tremendous industrial applications. The common desire is to efficiently generate nanoparticles with a desired size, size distribution, and size stability. Recently, Flash NanoPrecipition (FNP) technique with a fast, continuous, and easily scalable process has been developed to efficiently generate hydrophobe-loaded nanoparticles. This dissertation extended this technique, optimized process conditions and material formulations, and gave new insights into the mechanism and kinetics of nanoparticle formation. This dissertation demonstrated successful generation of spherical beta-carotene nanoparticles with an average diameter of 50--100 nm (90 wt% nanoparticles below 200 nm), good size stability (maintained an average diameter below 200 nm for at least one week in saline), and much higher loading (80--90 wt%) than traditional carriers, such as micelles and polymersomes (typically <20 wt%). Moreover, the nanoparticles are amorphous and expected to have a high dissolution rate and bioavailability. To give insights into the mechanism and kinetics of nanoparticle formation, much remarkable evidence supported the kinetically frozen structures of the nanoparticles rather than the thermodynamic equilibrium micelles. Time scales of the particle formation via FNP were proposed. To optimize the material formulations, either polyelectrolytes (i.e., epsilon-polylysine, branched and linear poly(ethylene imine), and chitosan) or amphiphilic diblock copolymers (i.e., polystyrene-b-poly(ethylene glycol) (PS-b-PEG), polycarprolactone-b-poly(ethylene glycol) (PCL-b-PEG), poly(lactic acid)-b-poly(ethylene glycol) (PLA-b-PEG), and poly(lactic-co-glycolic acid)-b-poly(ethylene glycol) (PLGA-b-PEG)) were selectively screened to study the nanoparticle size, distribution, and stability. The effect of the molecular weight of the polymers and pH were also studied. Chitosan and PLGA-b-PEG best stabilized the beta-carotene nanoparticles. Solubility of the hydrophobic drug solute in the aqueous mixture was considered to dominate the nanoparticle stability (i.e., size and morphology) in terms of Ostwald ripening and recrystallization. The lower solubility the drug is of, the greater stability the nanoparticles have. Chemically bonding drug compounds with cleavable hydrophobic moieties to form prodrugs were used to enhance their hydrophobicity and thus the nanoparticle stability. It opened a generic strategy to enhance the stability of nanoparticles formed via FNP. beta-carotene, paclitaxel, paclitaxel prodrug, betulin, hydrocortisone, and hydrocortisone prodrug as the drugs were studied. Solubility parameter (delta), and octanol/water partition coefficients (LogP), provide hydrophobicity indicators for the compounds. LogP showed a good correlation with the nanoparticle stability. An empirical rule was built to conveniently predict particle stability for randomly selected drugs. To optimize the process conditions, two-stream confined impinging jet mixer (CIJ) and four-stream confined vortex jet mixer were used. The particle size was studied by varying drug and polymer concentrations, and flow rate (corresponding to Reynolds number (Re)). To extend the FNP technique, this dissertation demonstrated successful creation of stabilized nanoparticles by integrating an in-situ reactive coupling of a hydrophilic polymer block with a hydrophobic one with FNP. The kinetics of the fast coupling reaction was studied. This dissertation also introduced polyelectrolytes (i.e., epsilon-polylysine, poly(ethylene imine), and chitosan) into FNP to electrosterically stabilize nanoparticles.

Two-Dimensional Self-Assembly and Chemical Synthesis of Charged Gold Nanoparticles in Non-Polar Solvents

NASA Astrophysics Data System (ADS)

Martin, Matthew Nichols

Gold nanoparticles between 1 and 10 nm in diameter exhibit size-dependent electronic and optical properties that cannot be explained by molecular science and which deviate significantly from their bulk counterparts. For example, the melting temperature of gold nanoparticles less than 5 nm in diameter is around 300 °C [1], whereas bulk gold melts at over 1000 °C [2]. Gold nanoparticles require precise control over particle diameter in order to exploit and tailor their unique properties; however, tuning the size reproducibly and predictably has proved to be a challenge. One of the most difficult obstacles to overcome is nanoparticle aggregation, since nanoparticles flocculate at room temperature quite readily. In 1994, Brust et al. solved the aggregation problem by introducing monolayer protection coatings on gold nanoparticles, in which organic ligand molecules are attached to the nanoparticle surface and create a physical barrier between the gold core and solvent. This was a definitive solution to size stability, since nanoparticles never aggregate, however the synthesis method does not generate monodisperse nanoparticles and has poor size-tuning capabilities. We developed a synthesis method for gold nanoparticles that improves greatly upon the Brust method. Starting from scratch, we discovered a "sweet zone" for aqueous gold nanoparticles, revealing how to make "naked" (stabilizer-free) gold nanoparticles which are continuously and precisely controlled between 3.2 and 5.2 nm in diameter, both reproducibly and predictably. Naked nanoparticles are then coated with organic 1-dodecanethiol ligand molecules, and transferred to hexane. Since all reaction byproducts remain in the water-phase, no postsynthesis cleaning or size-filtering is necessary, reducing the total synthesis time from ~24 hours in the Brust method, to less than 10 minutes. Surprisingly, our nanoparticles are highly negatively charged in nonpolar solvents. This unexpectedly caused nanoparticles to be unstable in toluene but stable in hexane. Consequently, nanoparticles float to the air-toluene interface, and after evaporation of toluene, form large 2D monolayer films of nanoparticle that are uniform at nanometer, micrometer, and millimeter length scales. This facile 2D self-assembly method also displays extremely size-dependent features in the 3.2 -- 5.2 nm range. Additionally, we managed to expand our synthesis method to include smaller gold nanoparticles. Since small gold clusters less than 2 nm in diameter are exponentially more efficient than other conventional catalysts, we labored to synthesize nanoclusters with diameters less than 2 nm, and fortunately, reduced the synthesis time to 2 minutes. With complete size control of gold nanoparticles between 1 and 5 nm, we have developed a truly novel synthesis method that forms a strong basis for many interesting studies. We have also discovered a novel method for place exchange reactions of organic molecular coatings. Ligand exchange of water-soluble thiols for alkylamines was performed at room temperature and occurred in less than 10 seconds, and allowed for the phase-transfer of nanoparticles from nonpolar solvents back to water. This method is extremely useful for the biological nanoparticle community as they are already using nanoparticles for drug delivery, DNA sensing, and molecular recognition.

Photocatalytic activity of SnO{sub 2} nanoparticles in methylene blue degradation

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

Kim, Sung Phil; Choi, Myong Yong, E-mail: mychoi@gnu.ac.kr; Choi, Hyun Chul, E-mail: chc12@chonnam.ac.kr

2016-02-15

Highlights: • Nanosized SnO{sub 2} photocatalysts were prepared with a precipitation method. • SnO{sub 2} nanoparticles displayed high photocatalytic activities for the MB degradation. • OH radicals are the main active species in photocatalysis on the SnO{sub 2} nanoparticles. - Abstract: Nanosized SnO{sub 2} photocatalysts were prepared with a precipitation method and were characterized by performing transmission electron microscopy (TEM), powder X-ray diffraction (XRD), and X-ray absorption spectroscopy (XAS). The powder XRD results revealed that the SnO{sub 2} nanoparticles have a typical tetragonal rutile (cassiterite) structure and the average crystallite size was found to be approximately 4.5 nm by usingmore » the Debye–Scherrer equation. The prepared SnO{sub 2} nanoparticles consist of agglomerated particles with a mean diameter of around 4–5 nm according to the analysis of TEM images. The XAS data confirmed that the prepared samples have cassiterite structures with tin oxidation state of +4. The prepared SnO{sub 2} nanoparticles were found to exhibit approximately 3.8 times higher activity than bulk SnO{sub 2} in the photodegradation of methylene blue. On the basis of a trapping experiment, we developed a possible mechanism for the photodegradation on SnO{sub 2} nanoparticles.« less

Ferroxidase activity of apoferritin is increased in the presence of platinum nanoparticles.

PubMed

Sennuga, Afolake; van Marwijk, Jacqueline; Whiteley, Chris G

2012-01-27

The ferroxidase activity of horse spleen apoferritin (HSAF) is increased by nine-fold in the presence of platinum nanoparticles. HSAF was mixed with varying concentrations of K2PtCl4 followed by a 20-fold concentration of sodium borohydride to afford Pt:HSAF nanoparticle complexes in a ratio of between 1:250 and 1:4000. Typical colour changes, from colourless or pale yellow to brown, occurred that were dependent on the amount of platinum present. These complexes were characterized by UV/vis, inductively coupled plasma optical emission spectroscopy, Fourier transform infrared, transmission electron microscopy and energy dispersive x-ray spectroscopy. Transmission electron microscopy analysis revealed that the size of nanoparticles increased as the molar ratio of platinum to HSAF increased with an average size diameter of 2-6 nm generated with HSAF:platinum molar ratios of 1:250-1:4000. Fourier transform infrared spectroscopy (FTIR) spectra showed no distinct changes in the structure of HSAF but confirmed that the nanoparticles were attached to the protein. The effect of platinum nanoparticles on the ferroxidase activity of HSAF showed a specific activity of 360 ρmol min(-1) mg(-1), (nine-fold increase over the control) at the molar ratio of HSAF:platinum nanoparticles of 1:1000.

Laser-generated bismuth nanoparticles for applications in imaging and radiotherapy

NASA Astrophysics Data System (ADS)

Torrisi, L.; Silipigni, L.; Restuccia, N.; Cuzzocrea, S.; Cutroneo, M.; Barreca, F.; Fazio, B.; Di Marco, G.; Guglielmino, S.

2018-08-01

Bismuth nanoparticles were obtained by laser ablation in water and characterized by using different physical techniques. Their shape, estimated by SEM measurements, was approximately spherical with an average diameter of about 25 nm, and a solution concentration of about 0.8 mg/ml was prepared. The formation of pure Bi nanoparticles was also confirmed by micro-Raman spectra which showed the characteristic first order Raman modes of rhombohedral bismuth. The presence of this phase was also supported by the XRD pattern. The EDX analysis indicated that the as-prepared nanoparticles contained Bi metallic element. The high Z of the nanoparticles in the solution shows effects of surface plasmon resonance in the near ultraviolet and visible regions, high mass absorption coefficient for X-ray interaction and high electronic and nuclear stopping powers for electron and ion beams. Such biocompatible solution can be injected in living systems, such as mice, in order to study the presence of uptake in different organs with high contrast spatial localization in the tissues where Bi nanoparticles are confined. The results indicate that Bi nanoparticles can be employed as high contrast medium for high resolution imaging in biological systems as well as target for exposition to ionizing radiation during radiotherapy or to visible light during hyperthermia of diseased cells.

Threshold heating temperature for magnetic hyperthermia: Controlling the heat exchange with the blocking temperature of magnetic nanoparticles

NASA Astrophysics Data System (ADS)

Pimentel, B.; Caraballo-Vivas, R. J.; Checca, N. R.; Zverev, V. I.; Salakhova, R. T.; Makarova, L. A.; Pyatakov, A. P.; Perov, N. S.; Tishin, A. M.; Shtil, A. A.; Rossi, A. L.; Reis, M. S.

2018-04-01

La0.75Sr0.25MnO3 nanoparticles with average diameter close to 20.9 nm were synthesized using a sol-gel method. Measurements showed that the heating process stops at the blocking temperaturesignificantly below the Curie temperature. Measurements of Specific Absorption Rate (SAR) as a function of AC magnetic field revealed a superquadratic power law, indicating that, in addition to usual Néel and Brown relaxation, the hysteresis also plays an important role in the mechanism of heating. The ability to control the threshold heating temperature, a low remanent magnetization and a low field needed to achieve the magnetic saturation are the advantages of this material for therapeutic magnetic hyperthermia.

Preparation of curcumin-loaded PCL-PEG-PCL triblock copolymeric nanoparticles by a microchannel technology.

PubMed

Guo, Fangyuan; Guo, Dingjia; Zhang, Wei; Yan, Qinying; Yang, Yan; Hong, Weiyong; Yang, Gensheng

2017-03-01

Biodegradable polymeric nanoparticles (NPs) have potential therapeutic applications; however, preparing NPs of a specific diameter and uniform size distribution is a challenge. In this work, we fabricated a microchannel system for the preparation of curcumin (Cur)-loaded NPs by the interfacial precipitation method, which rapidly and consistently generated stable NPs with a relatively smaller diameter, narrow size distribution, and higher drug-loading capacity and entrapment efficiency. Poly(ε-caprolactone)-poly(ethylene glycol)-poly (ε-caprolactone) triblock copolymers(PCEC) used as the carrier material was synthesized and characterized. Cur-loaded PCEC NPs had an average size of 167.2nm with a zeta potential of -29.23mV, and showed a loading capacity and drug entrapment efficiency of 15.28%±0.23% and 96.11%±0.13%, respectively. Meanwhile, the NPs demonstrated good biocompatibility and bioavailability, efficient cellular uptake, and long circulation time and a possible liver targeting effect in vivo. These results indicate that the Cur-loaded PCEC NPs can be used as drug carriers in controlled delivery systems and other biomedical applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Physico-chemical characterization of engineered metal oxide nanoparticles: the critical role of microscopy

NASA Astrophysics Data System (ADS)

La Fontaine, A.; Coleman, V. A.; Jämting, A. K.; Lawn, M.; Herrmann, J.; Miles, J. R.

2010-06-01

Three different methods for extracting zinc oxide (ZnO) and titanium dioxide (TiO2) nanoparticles from commercially available sunscreen were investigated to determine the most appropriate route for producing a sample suitable for measuring the primary particle size. Direct dilution of the formulation, centrifugal methods and chemical washing were trialed in combination with ultrasonic processing and surfactant addition to generate samples that are suitable for particle size analysis. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) were used to monitor the extraction and re-dispersion process. Washing with hexane, methanol and water to remove the formulation, in combination with pulsed high-powered ultrasonication and the addition of a charge-stabilizing surfactant was found to be the most efficient way of producing de-agglomerated samples. DLS measurements gave average hydrodynamic particle diameters of 87 nm for ZnO and 76 nm for TiO2, compared to equivalent spherical particle diameters of 21 +/- 12 nm for ZnO (81 particles) and 19 +/- 14 nm for TiO2 (81 particles) obtained from TEM analysis.

Room temperature ferromagnetism in Fe-doped CuO nanoparticles.

PubMed

Layek, Samar; Verma, H C

2013-03-01

The pure and Fe-doped CuO nanoparticles of the series Cu(1-x)Fe(x)O (x = 0.00, 0.02, 0.04, 0.06 and 0.08) were successfully prepared by a simple low temperature sol-gel method using metal nitrates and citric acid. Rietveld refinement of the X-ray diffraction data showed that all the samples were single phase crystallized in monoclinic structure of space group C2/c with average crystallite size of about 25 nm and unit cell volume decreases with increasing iron doping concentration. TEM micrograph showed nearly spherical shaped agglomerated particles of 4% Fe-doped CuO with average diameter 26 nm. Pure CuO showed weak ferromagnetic behavior at room temperature with coercive field of 67 Oe. The ferromagnetic properties were greatly enhanced with Fe-doping in the CuO matrix. All the doped samples showed ferromagnetism at room temperature with a noticeable coercive field. Saturation magnetization increases with increasing Fe-doping, becomes highest for 4% doping then decreases for further doping which confirms that the ferromagnetism in these nanoparticles are intrinsic and are not resulting from any impurity phases. The ZFC and FC branches of the temperature dependent magnetization (measured in the range of 10-350 K by SQUID magnetometer) look like typical ferromagnetic nanoparticles and indicates that the ferromagnetic Curie temperature is above 350 K.

Effect of AOT Microemulsion Composition on the Hydrodynamic Diameter and Electrophoretic Mobility of Titanium Oxide Nanoparticles

NASA Astrophysics Data System (ADS)

Shaparenko, N. O.; Beketova, D. I.; Demidova, M. G.; Bulavchenko, A. I.

2018-05-01

The hydrodynamic diameter and electrophoretic mobility of titania nanoparticles in AOT microemulsions are studied depending on their water content (from 0 to 1.5 vol %), chloroform content in n-decane-chloroform mixture (from 0 to 30 vol %) and temperature (from 0 to 60°C). Considerable changes in diameter (from 20 to 400 nm) are detected upon adding water to the microemulsion. The electrophoretic mobility grows by 2-3 times upon adding chloroform, or as the temperature falls. The observed features allow us to halve the time of electrophoretic concentration for 140 nm TiO2 nanoparticles, and to concentrate 14 nm nanoparticles that do not exhibit electrophoretic mobility in the absence of chloroform.

Green biosynthesis of silver nanoparticles using leaves extract of Artemisia vulgaris and their potential biomedical applications.

PubMed

Rasheed, Tahir; Bilal, Muhammad; Iqbal, Hafiz M N; Li, Chuanlong

2017-10-01

Biosynthesis of nanoparticles from plant extracts is receiving enormous interest due to their abundant availability and a broad spectrum of bioactive reducing metabolites. In this study, the reducing potential of Artemisia vulgaris leaves extract (AVLE) was investigated for synthesizing silver nanoparticles without the addition of any external reducing or capping agent. The appearance of blackish brown color evidenced the complete synthesis of nanoparticles. The synthesized silver nanoparticles were characterized by UV-vis spectroscopy, scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscope (TEM), atomic force microscopy (AFM) and Fourier transforms infrared spectroscopy (FT-IR) analysis. UV-vis absorption profile of the bio-reduced sample elucidated the main peak around 420nm, which correspond to the surface plasmon resonance of silver nanoparticles. SEM and AFM analyses confirmed the morphology of the synthesized nanoparticles. Similarly, particles with a distinctive peak of silver were examined with EDX. The average diameter of silver nanoparticles was about 25nm from Transmission Electron Microscopy (TEM). FTIR spectroscopy scrutinized the involvement of various functional groups during nanoparticle synthesis. The green synthesized nanoparticles presented effective antibacterial activity against pathogenic bacteria than AVLE alone. In-vitro antioxidant assays revealed that silver nanoparticles (AV-AgNPs) exhibited promising antioxidant properties. The nanoparticles also displayed a potent cytotoxic effect against HeLa and MCF-7 cell lines. In conclusion, the results supported the advantages of employing a bio-green approach for developing silver nanoparticles with antimicrobial, antioxidant, and antiproliferative activities in a simple and cost- competitive manner. Copyright © 2017 Elsevier B.V. All rights reserved.

Polarized Optical Scattering Measurements of Metallic Nanoparticles on a Thin Film Silicon Wafer

NASA Astrophysics Data System (ADS)

Liu, Cheng-Yang; Liu, Tze-An; Fu, Wei-En

2009-09-01

Light scattering has shown its powerful diagnostic capability to characterize optical quality surfaces. In this study, the theory of bidirectional reflectance distribution function (BRDF) was used to analyze the metallic nanoparticles' sizes on wafer surfaces. The BRDF of a surface is defined as the angular distribution of radiance scattered by the surface normalized by the irradiance incident on the surface. A goniometric optical scatter instrument has been developed to perform the BRDF measurements on polarized light scattering on wafer surfaces for the diameter and distribution measurements of metallic nanoparticles. The designed optical scatter instrument is capable of distinguishing various types of optical scattering characteristics, which are corresponding to the diameters of the metallic nanoparticles, near surfaces by using the Mueller matrix calculation. The metallic nanoparticle diameter of measurement is 60 nm on 2 inch thin film wafers. These measurement results demonstrate that the polarization of light scattered by metallic particles can be used to determine the size of metallic nanoparticles on silicon wafers.

Biopersistence of silver nanoparticles in tissues from Sprague–Dawley rats

PubMed Central

2013-01-01

Silver nanoparticles are known to be distributed in many tissues after oral or inhalation exposure. Thus, understanding the tissue clearance of such distributed nanoparticles is very important to understand the behavior of silver nanoparticles in vivo. For risk assessment purposes, easy clearance indicates a lower overall cumulative toxicity. Accordingly, to investigate the clearance of tissue silver concentrations following oral silver nanoparticle exposure, Sprague–Dawley rats were assigned to 3 groups: control, low dose (100 mg/kg body weight), and high dose (500 mg/kg body weight), and exposed to two different sizes of silver nanoparticles (average diameter 10 and 25 nm) over 28 days. Thereafter, the rats were allowed to recover for 4 months. Regardless of the silver nanoparticle size, the silver content in most tissues gradually decreased during the 4-month recovery period, indicating tissue clearance of the accumulated silver. The exceptions were the silver concentrations in the brain and testes, which did not clear well, even after the 4-month recovery period, indicating an obstruction in transporting the accumulated silver out of these tissues. Therefore, the results showed that the size of the silver nanoparticles did not affect their tissue distribution. Furthermore, biological barriers, such as the blood–brain barrier and blood-testis barrier, seemed to play an important role in the silver clearance from these tissues. PMID:24059869

Induction of apoptosis in cancer cells by NiZn ferrite nanoparticles through mitochondrial cytochrome C release

PubMed Central

Al-Qubaisi, Mothanna Sadiq; Rasedee, Abdullah; Flaifel, Moayad Husein; Ahmad, Sahrim Hj; Hussein-Al-Ali, Samer; Hussein, Mohd Zobir; Zainal, Zulkarnain; Alhassan, Fatah H; Taufiq-Yap, Yun H; Eid, Eltayeb EM; Arbab, Ismail Adam; Al-Asbahi, Bandar A; Webster, Thomas J; Zowalaty, Mohamed Ezzat El

2013-01-01

The long-term objective of the present study was to determine the ability of NiZn ferrite nanoparticles to kill cancer cells. NiZn ferrite nanoparticle suspensions were found to have an average hydrodynamic diameter, polydispersity index, and zeta potential of 254.2 ± 29.8 nm, 0.524 ± 0.013, and −60 ± 14 mV, respectively. We showed that NiZn ferrite nanoparticles had selective toxicity towards MCF-7, HepG2, and HT29 cells, with a lesser effect on normal MCF 10A cells. The quantity of Bcl-2, Bax, p53, and cytochrome C in the cell lines mentioned above was determined by colorimetric methods in order to clarify the mechanism of action of NiZn ferrite nanoparticles in the killing of cancer cells. Our results indicate that NiZn ferrite nanoparticles promote apoptosis in cancer cells via caspase-3 and caspase-9, downregulation of Bcl-2, and upregulation of Bax and p53, with cytochrome C translocation. There was a concomitant collapse of the mitochondrial membrane potential in these cancer cells when treated with NiZn ferrite nanoparticles. This study shows that NiZn ferrite nanoparticles induce glutathione depletion in cancer cells, which results in increased production of reactive oxygen species and eventually, death of cancer cells. PMID:24204141

Time-dependent growth of crystalline Au(0)-nanoparticles in cyanobacteria as self-reproducing bioreactors: 2. Anabaena cylindrica.

PubMed

Rösken, Liz M; Cappel, Felix; Körsten, Susanne; Fischer, Christian B; Schönleber, Andreas; van Smaalen, Sander; Geimer, Stefan; Beresko, Christian; Ankerhold, Georg; Wehner, Stefan

2016-01-01

Microbial biosynthesis of metal nanoparticles as needed in catalysis has shown its theoretical ability as an extremely environmentally friendly production method in the last few years, even though the separation of the nanoparticles is challenging. Biosynthesis, summing up biosorption and bioreduction of diluted metal ions to zero valent metals, is especially ecofriendly, when the bioreactor itself is harmless and needs no further harmful reagents. The cyanobacterium Anabaena cylindrica (SAG 1403.2) is able to form crystalline Au(0)-nanoparticles from Au(3+) ions and does not release toxic anatoxin-a. X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and laser-induced breakdown spectroscopy (LIBS) are applied to monitor the time-dependent development of gold nanoparticles for up to 40 hours. Some vegetative cells (VC) are filled with nanoparticles within minutes, while the extracellular polymeric substances (EPS) of vegetative cells and the heterocyst polysaccharide layer (HEP) are the regions, where the first nanoparticles are detected on most other cells. The uptake of gold starts immediately after incubation and within four hours the average size remains constant around 10 nm. Analyzing the TEM images with an image processing program reveals a wide distribution for the diameter of the nanoparticles at all times and in all regions of the cyanobacteria. Finally, the nanoparticle concentration in vegetative cells of Anabaena cylindrica is about 50% higher than in heterocysts (HC). These nanoparticles are found to be located along the thylakoid membranes.

Molecular dynamics simulations of aggregation of copper nanoparticles with different heating rates

NASA Astrophysics Data System (ADS)

Li, Qibin; Wang, Meng; Liang, Yunpei; Lin, Liyang; Fu, Tao; Wei, Peitang; Peng, Tiefeng

2017-06-01

Molecular dynamics simulations were employed to investigate the heating rates' effect on aggregation of two copper nanoparticles. The aggregation can be distinguished into three distinct regimes by the contacting and melting of nanoparticles. The nanoparticles contacting at a lower temperature during the sintering with lower heating rate, meanwhile, some temporary stacking fault exists at the contacting neck. The aggregation properties of the system, i.e. neck diameter, shrinkage ratio, potential energy, mean square displacement (MSD) and relative gyration radius, experience drastic changes due to the free surface annihilation. After the nanoparticles coalesced for a stable period, the shrinkage ratio, MSD, relative gyration radius and neck diameter of the system are dramatically changed during the melting process. It is shown that the shrinkage ratio and MSD have relative larger increasing ratio for a lower heating rate. While the evolution of the relative gyration radius and neck diameter is only sensitive to the temperature.

One-step green route to narrowly dispersed copper nanocrystals

NASA Astrophysics Data System (ADS)

Wu, Chunwei; Mosher, Brian P.; Zeng, Taofang

2006-12-01

We report a total "green" chemical method in aqueous solution for synthesizing stable narrowly distributed copper nanoparticles with average diameter less than 5 nm in the presence of Polyvinylpyrrolidone (PVP) as a stabilizer and without any inert gas protection. In our synthesis route, ascorbic acid, natural vitamin C (VC), an excellent oxygen scavenger, acts as both reducing agent and antioxidant, to reduce the metallic ion precursor, and to effectively prevent the common oxidation process of the newborn pure copper nanoclusters.

Solvothermal in situ synthesis of Fe{sub 3}O{sub 4}-multi-walled carbon nanotubes with enhanced heterogeneous Fenton-like activity

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

Deng, Jingheng; Wen, Xianghua, E-mail: xhwen@tsinghua.edu.cn; Wang, Qinian

Graphical abstract: After purification, the multi-wall carbon nanotubes (MWCNTs) act as seeds for Fe{sub 3}O{sub 4} nanoparticles heterogeneous nucleation. The Fe{sub 3}O{sub 4} nanoparticles with diameter range of 4.2–10.0 nm synthesized in situ on the MWCNTs under solvothermal condition. The formed nano Fe{sub 3}O{sub 4}-MWCNTs decolorized the Acid Orange II effectively via Fenton-like reaction. Highlights: ► The amount of water tunes size and size distribution of the Fe{sub 3}O{sub 4} nanoparticles (FNs). ► FNs are homogeneously coated on the multi-walled carbon nanotubes (MWCNTs). ► FNs have diameters in the range of 4.2–10.0 nm, average grain size of 7.4 nm. ►more » Fe{sub 3}O{sub 4}-MWCNTs are used as a Fenton-like catalyst to decompose Acid Orange II. ► Fe{sub 3}O{sub 4}-MWCNTs displayed a higher activity than nanometer-size Fe{sub 3}O{sub 4}. -- Abstract: Fe{sub 3}O{sub 4}-multi-walled carbon nanotubes (Fe{sub 3}O{sub 4}-MWCNTs) hybrid materials were synthesized by a solvothermal process using acid treated MWCNTs and iron acetylacetonate in a mixed solution of ethylene glycol and ultrapure water. The materials were characterized using X-ray powder diffraction, scanning and transmission electron microscopy, X-ray photoelectron spectroscopy, and vibrating sample magnetometry. The results showed that a small amount of water in the synthesis system played a role in controlling crystal phase formation, size of Fe{sub 3}O{sub 4}, and the homogeneous distribution of the Fe{sub 3}O{sub 4} nanoparticles deposited on the MWCNTs. The Fe{sub 3}O{sub 4} nanoparticles had diameters in the range of 4.2–10.0 nm. They displayed good superparamagnetism at room temperature and their magnetization was influenced by the reaction conditions. They were used as a Fenton-like catalyst to decompose Acid Orange II and displayed a higher activity than nanometer-size Fe{sub 3}O{sub 4}.« less

Fabrication, Characterization and Cytotoxicity of Spherical-Shaped Conjugated Gold-Cockle Shell Derived Calcium Carbonate Nanoparticles for Biomedical Applications

NASA Astrophysics Data System (ADS)

Kiranda, Hanan Karimah; Mahmud, Rozi; Abubakar, Danmaigoro; Zakaria, Zuki Abubakar

2018-01-01

The evolution of nanomaterial in science has brought about a growing increase in nanotechnology, biomedicine, and engineering fields. This study was aimed at fabrication and characterization of conjugated gold-cockle shell-derived calcium carbonate nanoparticles (Au-CSCaCO3NPs) for biomedical application. The synthetic technique employed used gold nanoparticle citrate reduction method and a simple precipitation method coupled with mechanical use of a Programmable roller-ball mill. The synthesized conjugated nanomaterial was characterized for its physicochemical properties using transmission electron microscope (TEM), field emission scanning electron microscope (FESEM) equipped with energy dispersive X-ray (EDX) and Fourier transform infrared spectroscopy (FTIR). However, the intricacy of cellular mechanisms can prove challenging for nanomaterial like Au-CSCaCO3NPs and thus, the need for cytotoxicity assessment. The obtained spherical-shaped nanoparticles (light-green purplish) have an average diameter size of 35 ± 16 nm, high carbon and oxygen composition. The conjugated nanomaterial, also possesses a unique spectra for aragonite polymorph and carboxylic bond significantly supporting interactions between conjugated nanoparticles. The negative surface charge and spectra absorbance highlighted their stability. The resultant spherical shaped conjugated Au-CSCaCO3NPs could be a great nanomaterial for biomedical applications.

Detection and Monitoring of Toxic Chemical at Ultra Trace Level by Utilizing Doped Nanomaterial

PubMed Central

Khan, Sher Bahadar; Rahman, Mohammed M.; Akhtar, Kalsoom; Asiri, Abdullah M.

2014-01-01

Composite nanoparticles were synthesized by eco-friendly hydrothermal process and characterized by different spectroscopic techniques. All the spectroscopic techniques suggested the synthesis of well crystalline optically active composite nanoparticles with average diameter of ∼30 nm. The synthesized nanoparticles were applied for the development of chemical sensor which was fabricated by coating the nanoparticles on silver electrode for the recognition of phthalimide using simple I–V technique. The developed sensor exhibited high sensitivity (1.7361 µA.mM−1.cm−2), lower detection limit (8.0 µM) and long range of detection (77.0 µM to 0.38 M). Further the resistances of composite nanoparticles based sensor was found to be 2.7 MΩ which change from 2.7 to 1.7 with change in phthalimide concentration. The major advantages of the designed sensor over existing sensors are its simple technique, low cost, lower detection limit, high sensitivity and long range of detection. It can detect phthalimide even at trace level and sense over wide range of concentrations. Therefore the composite nanoparticals would be a better choice for the fabrication of phthalimide chemical sensor and would be time and cost substituted implement for environmental safety. PMID:25329666

Biotinylated vanadium and chromium sulfide nanoparticles as probes for colocalization of membrane proteins.

PubMed

Loukanov, Alexandre; Emin, Saim

2016-09-01

We report the microemulsion synthesis of vanadium and chromium sulfide nanoparticles (NPs) and their biological application as nanoprobes for colocalization of membrane proteins. Spherical V2 S3 and Cr2 S3 NPs were prepared in reverse microemulsion droplets, as nanoreactors, obtained by the surfactant sodium bis(2-ethylhexyl) sulfosuccinate (AOT) in nonpolar organic phase (heptane). Electron microscopic data indicated that the size distribution of the nanoparticles was uniform with an average diameter between 3 ÷ 5 nm. The prepared hydrophobic nanocrystals were transferred in aqueous phase by surface cap exchange of AOT with biotin-dihydrolipoic ligands. This substitution allows the nanoparticles solubility in aqueous solutions and confer their bioactivity. In addition, we report the conjugation procedure between α-Lipoic acid (LA) and biotin (abbreviated as biotin-LA). The biotin-LA structure was characterized by 1D and 2D NMR spectroscopy. The biotinylated vanadium and chromium sulfide nanoparticles were tested as probes for colocalization of glutamate receptors on sodium-dodecyl-sulfate-digested replica prepared from rat hippocampus. The method suggests their high labeling efficiency for study of membrane biological macromolecules. Microsc. Res. Tech. 79:799-805, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Control of Partial Coalescence of Self-Assembled Metal Nano-Particles across Lyotropic Liquid Crystals Templates towards Long Range Meso-Porous Metal Frameworks Design

PubMed Central

Dumée, Ludovic F.; Lemoine, Jean-Baptiste; Ancel, Alice; Hameed, Nishar; He, Li; Kong, Lingxue

2015-01-01

The formation of purely metallic meso-porous metal thin films by partial interface coalescence of self-assembled metal nano-particles across aqueous solutions of Pluronics triblock lyotropic liquid crystals is demonstrated for the first time. Small angle X-ray scattering was used to study the influence of the thin film composition and processing conditions on the ordered structures. The structural characteristics of the meso-structures formed demonstrated to primarily rely on the lyotropic liquid crystal properties while the nature of the metal nano-particles used as well as the their diameters were found to affect the ordered structure formation. The impact of the annealing temperature on the nano-particle coalescence and efficiency at removing the templating lyotropic liquid crystals was also analysed. It is demonstrated that the lyotropic liquid crystal is rendered slightly less thermally stable, upon mixing with metal nano-particles and that low annealing temperatures are sufficient to form purely metallic frameworks with average pore size distributions smaller than 500 nm and porosity around 45% with potential application in sensing, catalysis, nanoscale heat exchange, and molecular separation. PMID:28347094

Toxicity of silver nanoparticles in biological systems: Does the complexity of biological systems matter?

PubMed

Vazquez-Muñoz, Roberto; Borrego, Belen; Juárez-Moreno, Karla; García-García, Maritza; Mota Morales, Josué D; Bogdanchikova, Nina; Huerta-Saquero, Alejandro

2017-07-05

Currently, nanomaterials are more frequently in our daily life, specifically in biomedicine, electronics, food, textiles and catalysis just to name a few. Although nanomaterials provide many benefits, recently their toxicity profiles have begun to be explored. In this work, the toxic effects of silver nanoparticles (35nm-average diameter and Polyvinyl-Pyrrolidone-coated) on biological systems of different levels of complexity was assessed in a comprehensive and comparatively way, through a variety of viability and toxicological assays. The studied organisms included viruses, bacteria, microalgae, fungi, animal and human cells (including cancer cell lines). It was found that biological systems of different taxonomical groups are inhibited at concentrations of silver nanoparticles within the same order of magnitude. Thus, the toxicity of nanomaterials on biological/living systems, constrained by their complexity, e.g. taxonomic groups, resulted contrary to the expected. The fact that cells and virus are inhibited with a concentration of silver nanoparticles within the same order of magnitude could be explained considering that silver nanoparticles affects very primitive cellular mechanisms by interacting with fundamental structures for cells and virus alike. Copyright © 2017 Elsevier B.V. All rights reserved.

Long-circulating Janus nanoparticles made by electrohydrodynamic co-jetting for systemic drug delivery applications

PubMed Central

Rahmani, Sahar; Villa, Carlos H.; Dishman, Acacia F.; Grabowski, Marika E.; Pan, Daniel C.; Durmaz, Hakan; Misra, Asish C; Colón-Meléndez, Laura; Solomon, Michael J.; Muzykantov, Vladimir R.; Lahann, Joerg

2016-01-01

Background Nanoparticles with controlled physical properties have been widely used for controlled release applications. In addition to shape, the anisotropic nature of the particles can be an important design criterion to ensure selective surface modification or independent release of combinations of drugs. Purpose Electrohydrodynamic (EHD) co-jetting is used for the fabrication of uniform anisotropic nanoparticles with individual compartments and initial physicochemical and biological characterization is reported. Methods EHD co-jetting is used to create nanoparticles, which are characterized at each stage with scanning electron microscopy (SEM), structured illumination microscopy (SIM), dynamic light scattering (DLS) and nanoparticle tracking analysis (NTA). Surface immobilization techniques are used to incorporate polyethylene glycol (PEG) and I125 radiolabels into the nanoparticles. Particles are injected in mice and the particle distribution after 1, 4 and 24 hours is assessed. Results and discussion Nanoparticles with an average diameter of 105.7 nm are prepared by EHD co-jetting. The particles contain functional chemical groups for further surface modification and radiolabeling. The density of PEG molecules attached to the surface of nanoparticles is determined to range between 0.02 and 6.04 ligands per square nanometer. A significant fraction of the nanoparticles (1.2% injected dose per mass of organ) circulates in the blood after 24 h. Conclusion EHD co-jetting is a versatile method for the fabrication of nanoparticles for drug delivery. Circulation of the nanoparticles for 24 h is a pre-requisite for subsequent studies to explore defined targeting of the nanoparticles to a specific anatomic site. PMID:26453170

Fast removal of malachite green dye using novel superparamagnetic sodium alginate-coated Fe3O4 nanoparticles.

PubMed

Mohammadi, Abbas; Daemi, Hamed; Barikani, Mehdi

2014-08-01

In this study, superparamagnetic sodium alginate-coated Fe3O4 nanoparticles (Alg-Fe3O4) as a novel magnetic adsorbent were prepared by in situ coprecipitation method, in which Fe3O4 nanoparticles were precipitated from FeCl3 and FeCl2 under alkaline medium in the presence of sodium alginate. The Alg-Fe3O4 nanoparticles were used for removal of malachite green (MG) from aqueous solutions using batch adsorption technique. The characterization of synthesized nanoparticles was performed using XRD, FTIR, TEM, TGA and vibrating sample magnetometer (VSM) techniques. FTIR analysis of synthesized nanoparticles provided the evidence that sodium alginate was successfully coated on the surface of Fe3O4 nanoparticles. The FT-IR and TGA characterization showed that the Alg-Fe3O4 nanoparticles contained about 14% (w/w) of sodium alginate. Moreover, TEM analysis indicated that the average diameter of the Alg-Fe3O4 nanoparticles was about 12nm. The effects of adsorbent dosage, pH and temperature were investigated on the adsorption properties of MG onto Alg-Fe3O4 nanoparticles. The equilibrium adsorption data were modeled using the Langmuir and Freundlich isotherms. The maximum adsorption capacity obtained from Langmuir isotherm equation was 47.84mg/g. The kinetics of adsorption of MG onto Alg-Fe3O4 nanoparticles were investigated using the pseudo-first-order and pseudo-second-order kinetic models. The results showed that the adsorption of MG onto nanoparticles followed pseudo-second-order kinetic model. Copyright © 2014 Elsevier B.V. All rights reserved.

Nitric oxide-releasing polymeric nanoparticles against Trypanosoma cruzi

NASA Astrophysics Data System (ADS)

Seabra, A. B.; Kitice, N. A.; Pelegrino, M. T.; Lancheros, C. A. C.; Yamauchi, L. M.; Pinge-Filho, P.; Yamada-Ogatta, S. F.

2015-05-01

Chagas disease, also known as American trypanosomiasis, is a potentially life-threatening illness caused by the protozoan parasite, Trypanosoma cruzi (T. cruzi), and the disease remains a major health problem in many Latin American countries. Several papers report that the killing of the parasite is dependent on the production of nitric oxide (NO). The endogenous free radical NO is an important cellular signalling molecule that plays a key role in the defense against pathogens, including T. cruzi. As T. cruzi is able to compromise host macrophages decreasing endogenous NO production, the administration of exogenous NO donors represents an interesting strategy to combat Chagas disease. Thus, the aims of this study were to prepare and evaluate the antimicrobial activity of NO-releasing polymeric nanoparticles against T. cruzi. Biocompatible polymeric nanoparticles composed of chitosan/sodium tripolyphosphate(TPP) were prepared and used to encapsulate mercaptosuccinic acid (MSA), which is a thiol-containing molecule. Nitrosation of free thiols (SH) groups of MSA were performed by the addition of equimolar amount of sodium nitrite (NaNO2), leading to the formation of S-nitroso-MSA-containing nanoparticles. These polymeric nanoparticles act as spontaneous NO donors, with free NO release. The results show the formation of nanoparticles with average hydrodynamic diameter ranging from 270 to 500 nm, average of polydispersity index of 0.35, and encapsulation efficiency in the range of 99%. The NO release kinetics from the S-nitroso-MSA-containing nanoparticles showed sustained and controlled NO release over several hours. The microbicidal activity of S-nitroso-MSA-containing nanoparticles was evaluated by incubating NO-releasing nanoparticles (200 - 600 μg/mL) with replicative and non-infective epimastigote, and non-replicative and infective trypomastigote forms of T. cruzi. In addition, a significant decrease in the percentage of macrophage-infected (with amastigotes) and NO-releasing nanoparticle-treated cells was observed. Taken together, our results reveal a potent toxic effect of NO-releasing polymeric nanoparticles against different life cycle forms of T. cruzi, indicating that the encapsulation of the NO donor S-nitroso-MSA represents an interesting approach to combat and to prevent Chagas disease.

Formulation and Evaluation of Solid Lipid Nanoparticles of Ramipril

PubMed Central

Ekambaram, P; Abdul, Hasan Sathali A

2011-01-01

Solid lipid nanoparticles are typically spherical with an average diameter between 1 and 1000 nm. It is an alternative carrier system to tradition colloidal carriers, such as, emulsions, liposomes, and polymeric micro and nanoparticles. Ramipril is an antihypertensive agent used in the treatment of hypertension. Its oral bioavailability is 28% and it is rapidly excreted through the renal route. This drug has many side effects such as, postural hypotension, hyperkalemia, and angioedema, when given as an immediate dosage form. To overcome the side effects and to increase the bioavailability of ramipril, solid lipid nanoparticles of ramipril are prepared by using lipids (glyceryl monostearate and glyceryl monooleate) with stabilizers (tween 80, poloxamer 188, and span 20). The prepared formulations have been evaluated for entrapment efficiency, drug content, in-vitro drug release, particle size analysis, scanning electron spectroscopy, Fourier transform-infrared studies, and stability. A formulation containing glyceryl monooleate, stabilized with span 20 as surfactant showed prolonged drug release, smaller particle size, and narrow particle size distribution, as compared to other formulations with different surfactants and lipids. PMID:21897661

IF-WS{sub 2} nanoparticles size design and synthesis via chemical reduction

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

Ghoreishi, S.M., E-mail: ghoreshi@cc.iut.ac.ir; Meshkat, S.S.; Dadkhah, A.A.

2010-05-15

An innovative synthesis of inorganic fullerene-like disulfide tungsten (IF-WS{sub 2}) nanoparticles was developed using a chemical reduction reaction in a horizontal quartz reactor. In this process, first tungsten trisulfide (WS{sub 3}) was formed via a chemical reaction of tetra thiotungstate ammonium ((NH{sub 4}){sub 2}WS{sub 4}), polyethylene glycol (PEG), and hydrochloric acid (HCl) at ambient temperature and pressure. Subsequently, WS{sub 3} was reacted with hydrogen (H{sub 2}) at high temperature (1173-1373 K) in a quartz tube. The produced WS{sub 2} nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDAX), and transmission electron microscopy (TEM). Themore » characterization results indicated that the high-purity (100%) IF-WS{sub 2} nanoparticles were produced. Moreover, addition of surfactant (PEG) and higher operating temperature (1173-1373 K) decreased the particles agglomeration, and consequently led to the reduction of average diameter of WS{sub 2} particles in the range of 50-78 nm. The developed method is simple, environmentally compatible, and cost-effective in contrast to the conventional techniques.« less

The Enhanced Photo-Electrochemical Detection of Uric Acid on Au Nanoparticles Modified Glassy Carbon Electrode

NASA Astrophysics Data System (ADS)

Shi, Yuting; Wang, Jin; Li, Shumin; Yan, Bo; Xu, Hui; Zhang, Ke; Du, Yukou

2017-07-01

In this work, a sensitive and novel method for determining uric acid (UA) has been developed, in which the glassy carbon electrode (GCE) was modified with electrodeposition Au nanoparticles and used to monitor the concentration of UA with the assistant of visible light illumination. The morphology of the Au nanoparticles deposited on GCE surface were characterized by scanning electron microscope (SEM) and the nanoparticles were found to be well-dispersed spheres with the average diameter approaching 26.1 nm. A series of cyclic voltammetry (CV) and differential pulse voltammetry (DPV) measurements have revealed that the introduction of visible light can greatly enhance both the strength and stability of response current due to the surface plasmon resonance (SPR). Specifically, the DPV showed a linear relationship between peak current and UA concentration in the range of 2.8 to 57.5 μM with the equation of I pa (μA) = 0.0121 c UA (μM) + 0.3122 ( R 2 = 0.9987). Herein, the visible light illuminated Au/GCE possesses a potential to be a sensitive electrochemical sensor in the future.

Bacterial adhesion and inactivation on Ag decorated TiO2-nanotubes under visible light: Effect of the nanotubes geometry on the photocatalytic activity.

PubMed

Hajjaji, A; Elabidi, M; Trabelsi, K; Assadi, A A; Bessais, B; Rtimi, S

2018-06-05

This study investigates the effect of the diameter of TiO 2 nanotubes and silver decorated nanotubes on optical properties and photocatalytic inactivation of Escherichia coli under visible light. The TiO 2 nanotubes (TiO 2 -NTs) were prepared using the electrochemical method varying the anodization potential starting from 20 V until 70 V. The Ag nanoparticles were carried out using the photoreduction process under the same experimental conditions. The diameter size was determined using the scanning electronic microscopy (SEM). TiO 2 -NTs diameter reached ∼100 nm at 70 V. Transmission electronic microscopy (TEM) imaging confirmed the TiO 2 -NTs surface decoration by silver nanoparticles. The Ag-NPs average size was found to be equal to 8 nm. The X-Ray diffraction (XRD) analysis confirm that all TiO 2 -NTs crystallize in the anatase phases regardless the used anodization potential. The decrease of the photoluminescence (PL) intensity of Ag NPs decorated TiO 2 -NTs indicates the decrease of the specific area when the nanotubes diameter increases. The UV-vis absorbance show that the absorption edges was bleu shifted with the increasing of nanotubes diameter, which can be explained by the increase of the crystallites average size. The bacterial adhesion and inactivation tests were carried in the dark and under light. Bacteria were seen to adhere on TiO 2 -NTs in the dark; however, under light the bacteria were killed before they establish a strong contact with the TiO 2 -NTs and Ag/TiO 2 -NTs surfaces. Bacterial inactivation kinetics were faster when the anodizing potential of the NTs-preparation increases. A total bacterial inactivation was obtained on ∼100 nm nanotubes diameter within 90 min. This result was attributed to the enhancement of the TNTs crystallinity leading to reduced surface defects. Redox catalysis was seen to occur under light on the TiO 2 -NTs and Ag/TiO 2 -NTs. the photo-induced antibacterial activity on the AgO/Ag 2 O decorated TiO 2 -NTs was attributed to the interfacial charge transfer mechanism (IFCT). Copyright © 2018 Elsevier B.V. All rights reserved.

Cytotoxicity and cellular uptake of different sized gold nanoparticles in ovarian cancer cells

NASA Astrophysics Data System (ADS)

Kumar, Dhiraj; Mutreja, Isha; Chitcholtan, Kenny; Sykes, Peter

2017-11-01

Nanomedicine has advanced the biomedical field with the availability of multifunctional nanoparticles (NPs) systems that can target a disease site enabling drug delivery and helping to monitor the disease. In this paper, we synthesised the gold nanoparticles (AuNPs) with an average size 18, 40, 60 and 80 nm, and studied the effect of nanoparticles size, concentration and incubation time on ovarian cancer cells namely, OVCAR5, OVCAR8, and SKOV3. The size measured by transmission electron microscopy images was slightly smaller than the hydrodynamic diameter; measured size by ImageJ as 14.55, 38.13, 56.88 and 78.56 nm. The cellular uptake was significantly controlled by the AuNPs size, concentration, and the cell type. The nanoparticles uptake increased with increasing concentration, and 18 and 80 nm AuNPs showed higher uptake ranging from 1.3 to 5.4 μg depending upon the concentration and cell type. The AuNPs were associated with a temporary reduction in metabolic activity, but metabolic activity remained more than 60% for all sample types; NPs significantly affected the cell proliferation activity in first 12 h. The increase in nanoparticle size and concentration induced the production of reactive oxygen species in 24 h.

Tannase immobilisation by amino-functionalised magnetic Fe3O4-chitosan nanoparticles and its application in tea infusion.

PubMed

Li, Ruyi; Fu, Guiming; Liu, Chengmei; McClements, David Julian; Wan, Yin; Wang, Shaoman; Liu, Ting

2018-07-15

The tannase (from Aspergillus niger) was immobilised by glutaraldehyde conjugation to amino-functionalised chitosan-coated magnetic nanoparticles (Fe 3 O 4 -CS nanoparticles). Fourier-transform infrared spectroscopy and thermo-gravimetric analysis showed that chitosan was coated on the surface of magnetic nanoparticles. Transmission electron microscopy indicated that the synthesised nanoparticles (Fe 3 O 4 -CS) were almost spherical or ellipsoidal with an average diameter of 5.97 ± 1.25 nm. The stability and functionality of free and immobilised tannase were compared. Both forms of tannase exhibited the same optimal temperature of 30 °C, whereas the optimal pH value of immobilised tannase (pH 4.5) was lower than that of the free tannase (pH 5.5). The pH and thermal stabilities of immobilised tannase were significantly better than those of free tannase. Immobilised tannase retained over 50% of its initial activity after repeated utilisation for eight cycles. Furthermore, the immobilised tannase effectively improve the clarity and colour of black and green tea infusions. These results showed that amino-functionalised Fe 3 O 4 -CS nanoparticles are an efficient carrier for immobilising tannase, and immobilised tannase can be used in the clarification of tea infusion. Copyright © 2018 Elsevier B.V. All rights reserved.

Nanoparticles Formed by Acoustic Destruction of Microbubbles and Their Utilization for Imaging and Effects on Therapy by High Intensity Focused Ultrasound.

PubMed

Blum, Nicholas T; Yildirim, Adem; Chattaraj, Rajarshi; Goodwin, Andrew P

2017-01-01

This work reports that when PEG-lipid-shelled microbubbles with fluorocarbon interior (C 4 F 10 , C 5 F 12 , or C 6 F 14 ) are subjected to ultrasound pulses, they produce metastable, fluid-filled nanoparticles that can be re-imaged upon administration of HIFU. The nanoparticles produced by destruction of the microbubbles (MBNPs) are of 150 nm average diameter and can be re-imaged for up to an hour after creation for C 4 F 10 , and for at least one day for C 5 F 12 . The active species were found to be fluid (gas or liquid) filled nanoparticles rather than lipid debris. The acoustic droplet vaporization threshold of the nanoparticles was found to vary with the vapor pressure of the encapsulated fluorocarbon, and integrated image brightness was found to increase dramatically when the temperature was raised above the normal boiling point of the fluorocarbon. Finally, the vaporization threshold decreases in serum as compared to buffer, and administration of HIFU to the nanoparticles caused breast cancer cells to completely detach from their culture substrate. This work demonstrates a new functionality of microbubbles that could serve as a platform technology for ultrasound-based theranostics.

Room-temperature solution synthesis of Ag nanoparticle functionalized molybdenum oxide nanowires and their catalytic applications.

PubMed

Dong, Wenjun; Huang, Huandi; Zhu, Yanjun; Li, Xiaoyun; Wang, Xuebin; Li, Chaorong; Chen, Benyong; Wang, Ge; Shi, Zhan

2012-10-26

A simple chemical solution route for the synthesis of large-scale high-quality Ag nanoparticle functionalized molybdenum oxide nanowire at room temperature has been developed. In the synthesis, the protonated amine was intercalated into the molybdenum bronze layers to reduce the electrostatic force of the lamellar structures, and then the Ag nanoparticle functionalized long nanowires could be easily induced by a redox reaction between a molybdenum oxide-amine intermediate and Ag(+) at room temperature. The intercalation lamellar structures improved the nucleation and growth of the Ag nanoparticles, with the result that uniform Ag nanoparticles occurred on the surface of the MoO(3) nanowire. In this way Ag nanoparticles with average sizes of around 6 nm, and high-purity nanowires with mean diameter of around 50 nm and with typical lengths of several tens to hundreds of micrometers were produced. The heteronanostructured nanowires were intricately and inseparably connected to each other with hydrogen bonds and/or bridge oxygen atoms and packed together, forming a paper-like porous network film. The Ag-MoO(3) nanowire film performs a promoted catalytic property for the epoxidation of cis-cyclooctene, and the heteronanostructured nanowire film sensor shows excellent sensing performance to hydrogen and oxygen at room temperature.

Charge order suppression, emergence of ferromagnetism and absence of exchange bias effect in Bi0.25Ca0.75MnO3 nanoparticles: Electron paramagnetic resonance and magnetization studies

NASA Astrophysics Data System (ADS)

Singh, Geetanjali; Bhat, S. V.

2012-06-01

We report the results of magnetization and electron paramagnetic resonance (EPR) studies on nanoparticles (average diameter ˜ 30 nm) of Bi0.25Ca0.75MnO3 (BCMO) and compare them with the results on bulk BCMO. The nanoparticles were prepared using the nonaqueous sol-gel technique and characterized by XRD and TEM analysis. Magnetization measurements were carried out with a commercial physical property measurement system (PPMS). While the bulk BCMO exhibits a charge ordering transition at ˜230 K and an antiferromagnetic (AFM) transition at ˜130 K, in the nanoparticles, the CO phase is seen to have disappeared and a transition to a ferromagnetic (FM) state is observed at Tc ˜ 120 K. However, interestingly, the exchange bias effect observed in other nanomanganite ferromagnets is absent in BCMO nanoparticles. EPR measurements were carried out in the X-band between 8 and 300 K. Lineshape fitting to a Lorentzian with two terms (accounting for both the clockwise and anticlockwise rotations of the microwave field) was employed to obtain the relevant EPR parameters as functions of temperature. The results confirm the occurrence of ferromagnetism in the nanoparticles of BCMO.

Preparation and in vitro evaluation of actively targetable nanoparticles for SN-38 delivery against HT-29 cell lines.

PubMed

Ebrahimnejad, Pedram; Dinarvand, Rassoul; Sajadi, Abolghasem; Jaafari, Mahmoud Reza; Nomani, Ali Reza; Azizi, Ebrahim; Rad-Malekshahi, Mazda; Atyabi, Fatemeh

2010-06-01

SN-38 (7-ethyl-10-hydroxycamptothecin) is the active metabolite of irinotecan, which is 100-to 1000-fold more cytotoxic than irinotecan. Nevertheless, extreme hydrophobicity of SN-38 has prevented its clinical use. One way of improving the solubility and stability of SN-38 is to formulate the drug into nanoparticles. Folic acid has been widely used as a targeting moiety for various anticancer drugs. For folate-receptor-targeted anticancer therapy, SN-38 nanoparticles were produced using poly-lactide-co-glycolide-polyethylene glycol-folate (PLGA-PEG-FOL) conjugate by emulsification/solvent evaporation method. The FOL-conjugated di-block copolymer was synthesized by coupling the PLGA-PEG-NH(2) di-block copolymer with an activated folic acid. The conjugates were used for the formation of SN-38 nanoparticles with an average size of 200 nm in diameter. The SN-38 targeted nanoparticles showed a greater cytotoxicity against HT-29 cancer cells than SN-38 nontargeted nanoparticles. These results suggested that folate-targeted nanoparticles could be a potentially useful delivery system for SN-38 as an anticancer agent. SN-38 is the active metabolite of the chemotherapy agent irinotecan, which is 100-1000 fold more cytotoxic than irinotecan, but its extreme hydrophobicity has prevented its clinical use. In this paper, the authors present a nanotechnology-based approach targeting the folate-receptor with SN-38 loaded nanoparticles, demonstrating stronger cytotoxicity against HT-29 cancer cells than with control nanoparticles.

D, L-Sulforaphane Loaded Fe3O4@ Gold Core Shell Nanoparticles: A Potential Sulforaphane Delivery System.

PubMed

Kheiri Manjili, Hamidreza; Ma'mani, Leila; Tavaddod, Sharareh; Mashhadikhan, Maedeh; Shafiee, Abbas; Naderi-Manesh, Hossein

2016-01-01

A novel design of gold-coated iron oxide nanoparticles was fabricated as a potential delivery system to improve the efficiency and stability of d, l-sulforaphane as an anticancer drug. To this purpose, the surface of gold-coated iron oxide nanoparticles was modified for sulforaphane delivery via furnishing its surface with thiolated polyethylene glycol-folic acid and thiolated polyethylene glycol-FITC. The synthesized nanoparticles were characterized by different techniques such as FTIR, energy dispersive X-ray spectroscopy, UV-visible spectroscopy, scanning and transmission electron microscopy. The average diameters of the synthesized nanoparticles before and after sulforaphane loading were obtained ∼ 33 nm and ∼ 38 nm, respectively, when ∼ 2.8 mmol/g of sulforaphane was loaded. The result of cell viability assay which was confirmed by apoptosis assay on the human breast cancer cells (MCF-7 line) as a model of in vitro-cancerous cells, proved that the bare nanoparticles showed little inherent cytotoxicity, whereas the sulforaphane-loaded nanoparticles were cytotoxic. The expression rate of the anti-apoptotic genes (bcl-2 and bcl-xL), and the pro-apoptotic genes (bax and bak) were quantified, and it was found that the expression rate of bcl-2 and bcl-xL genes significantly were decreased when MCF-7 cells were incubated by sulforaphane-loaded nanoparticles. The sulforaphane-loaded into the designed gold-coated iron oxide nanoparticles, acceptably induced apoptosis in MCF-7 cells.

3D plasmonic transducer based on gold nanoparticles produced by laser ablation on silica nanowires

NASA Astrophysics Data System (ADS)

Gontad, F.; Caricato, A. P.; Manera, M. G.; Colombelli, A.; Resta, V.; Taurino, A.; Cesaria, M.; Leo, C.; Convertino, A.; Klini, A.; Perrone, A.; Rella, R.; Martino, M.

2016-05-01

Silica two-dimensional substrates and nanowires (NWs) forests have been successfully decorated with Au nanoparticles (NPs) through laser ablation by using a pulsed ArF excimer laser, for sensor applications. A uniform coverage of both substrate surfaces with NPs has been achieved controlling the number of laser pulses. The annealing of the as-deposited particles resulted in a uniform well-defined distribution of spherical NPs with an increased average diameter up to 25 nm. The deposited samples on silica NWs forest present a very good plasmonic resonance which resulted to be very sensitive to the changes of the environment (ethanol/water solutions with increasing concentration of ethanol) allowing the detection of changes on the second decimal digit of the refractive index, demonstrating its potentiality for further biosensing functionalities.

Amorphous Slater-Pauling like behaviour in magnetic nanoparticles alloys synthesized in liquids

NASA Astrophysics Data System (ADS)

Boyer, Paul; Ménard, David; Meunier, Michel

2012-09-01

Nanoparticles of Fe, Co, Ni, and their alloys, with an average diameter of 12 nm were synthesized in liquids using a laser. Their saturation magnetization exhibited a Slater-Pauling-like behaviour with two main differences compared to that expected in bulk materials. First, the amplitude of the magnetization was found to be roughly 5 times smaller. Second, the disappearance of the ferromagnetic (FM) behaviour occurred at Ni instead of the expected Ni0.6Cu0.4. The behaviour can be explained by the presence of non-magnetic oxidized shells which reduced the fraction of ferromagnetic atoms and induce through strain an amorphous structure in the metallic core. Annealing at 500 K leads to some crystallization of the particles and thus to a partial recovery of the expected magnetization.

Effects of ICG concentration and particle diameter on photophysical properties of ICG-doped nanoparticles

NASA Astrophysics Data System (ADS)

Crovisier, Jason; Bahmani, Baharak; Saleh, Reema; Vullev, Valentine; Anvari, Bahman

2014-03-01

The variety of nanoparticles developed by numerous investigators has presented a diverse platform for various optical imaging applications in biomedicine. We have previously reported that the FDA-approved chromophore Indocyanine Green (ICG) can be successfully encapsulated by cross-linked poly-allylamine hydrochloride (PAH)-Disodium Monophosphate (Na2HPO4) to form a nanoparticle for near-infrared imaging applications. The diameter of the constructs is dependent on the charge ratio between the polymer and salt used to encapsulate the chromophore. Modifications of the synthesis methods can alter the photophysical properties of the capsules, either through the adjustment of the charge ratio between PAH and Na2HPO4 or concentration of ICG successfully impregnated into the capsule. Through understanding the effects of tuning the nanoparticle properties, the photophysical characteristics of the constructs can be optimized. Here we present the results of adjusting the diameter of the nanoparticle and amount of ICG on the hydrodynamic diameters, absorption and fluorescence characteristics, and the relative fluorescence quantum yield. Optimizing the photophysical properties of the constructs can lead to increased imaging sensitivity and contrast for potential translational applications, including tumor imaging, which may utilize these nanoconstructs.

A molecular dynamics study of melting and dissociation of tungsten nanoparticles

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

Li, Min; Wang, Jun; Fu, Baoqin

2015-12-15

Molecular dynamics simulations were conducted to study the melting and dissociation of free tungsten nanoparticles. For the various interatomic potentials applied, the melting points of the tungsten nanoparticles increased with increasing nanoparticle diameter. Combining these results with the melting point of bulk tungsten in the experiment, the melting point of nanoparticles with diameters ranging from 4 to 12 nm could be determined. As the temperature increases, free nanoparticles are subject to dissociation phenomena. The dissociation rate was observed to follow Arrhenius behavior, and the Meyer–Neldel rule was obeyed. These results are useful in understanding the behavior of tungsten dust generatedmore » in nuclear fusion devices as well as for the preparation, formation, and application of tungsten powders.« less

A new measure of molecular attractions between nanoparticles near kT adhesion energy

NASA Astrophysics Data System (ADS)

Kendall, Kevin; Dhir, Aman; Du, Shangfeng

2009-07-01

The weak molecular attractions of nanoparticles are important because they drive self-assembly mechanisms, allow processing in dispersions e.g. of pigments, catalysts or device structures, influence disease through the attraction of viruses to cells and also cause potential toxic effects through nanoparticle interference with biomolecules and organs. The problem is to understand these small forces which pull nanoparticles into intimate contact; forces which are comparable with 3kT/2z the thermal impact force experienced by an average Brownian particle hitting a linear repulsive potential of range z. Here we describe a new method for measuring the atomic attractions of nanoparticles based on the observation of aggregates produced by these small forces. The method is based on the tracking of individual monosize nanoparticles whose diameter can be calculated from the Stokes-Einstein analysis of the tracks in aqueous suspensions. Then the doublet aggregates are distinguished because they move slower and are also very much brighter than the dispersed nanoparticles. By finding the ratio of doublets to singlets, the adhesive energy between the particles can be calculated from known statistical thermodynamic theory using assumptions about the shape of the interaction potential. In this way, very small adhesion energies of 2kT have been measured, smaller than those seen previously by atomic force microscopy (AFM) and scanning tunneling microscopy (STM).

Surface modification of protein enhances encapsulation in chitosan nanoparticles

NASA Astrophysics Data System (ADS)

Koyani, Rina D.; Andrade, Mariana; Quester, Katrin; Gaytán, Paul; Huerta-Saquero, Alejandro; Vazquez-Duhalt, Rafael

2018-04-01

Chitosan nanoparticles have a huge potential as nanocarriers for environmental and biomedical purposes. Protein encapsulation in nano-sized chitosan provides protection against inactivation, proteolysis, and other alterations due to environmental conditions, as well as the possibility to be targeted to specific tissues by ligand functionalization. In this work, we demonstrate that the chemical modification of the protein surface enhances the protein loading in chitosan nanocarriers. Encapsulation of green fluorescent protein and the cytochrome P450 was studied. The increase of electrostatic interactions between the free amino groups of chitosan and the increased number of free carboxylic groups in the protein surface enhance the protein loading, protein retention, and, thus, the enzymatic activity of chitosan nanoparticles. The chemical modification of protein surface with malonic acid moieties reduced drastically the protein isoelectric point increasing the protein interaction with the polycationic biomaterial and chitosan. The chemical modification of protein does not alter the morphology of chitosan nanoparticles that showed an average diameter of 18 nm, spheroidal in shape, and smooth surfaced. The strategy of chemical modification of protein surface, shown here, is a simple and efficient technique to enhance the protein loading in chitosan nanoparticles. This technique could be used for other nanoparticles based on polycationic or polyanionic materials. The increase of protein loading improves, doubtless, the performance of protein-loaded chitosan nanoparticles for biotechnological and biomedical applications.

The effect of the averaged structural and energetic features on the cohesive energy of nanocrystals

NASA Astrophysics Data System (ADS)

Ali Safaei

2010-03-01

The size dependency of the cohesive energy of nanocrystals is obtained in terms of their averaged structural and energetic properties, which are in direct proportion with their cohesive energies. The significance of the effect of the geometrical shape of nanoparticles on their thermal stability has been discussed. The model has been found to have good prediction for the case of Cu and Al nanoparticles, with sizes in the ranges of 1-22 nm and 2-22 nm, respectively. Defining a new parameter, named as the surface-to-volume energy-contribution ratio, the relative thermal stabilities of different nanoclusters and their different surface-crystalline faces are discussed and compared to the molecular dynamic (MD) simulation results of copper nanoclusters. Finally, based on the size dependency of the cohesive energy, a formula for the size-dependent diffusion coefficient has been presented which includes the structural and energetic effects. Using this formula, the faster-than-expected interdiffusion/alloying of Au(core)-Ag(shell) nanoparticles with the core-shell structure, the Au-core diameter of 20 nm and the Ag-shell thickness of 2.91 nm, has been discussed and the calculated diffusion coefficient has been found to be consistent with its corresponding experimental value.

Hierarchically self-assembled hexagonal honeycomb and kagome superlattices of binary 1D colloids.

PubMed

Lim, Sung-Hwan; Lee, Taehoon; Oh, Younghoon; Narayanan, Theyencheri; Sung, Bong June; Choi, Sung-Min

2017-08-25

Synthesis of binary nanoparticle superlattices has attracted attention for a broad spectrum of potential applications. However, this has remained challenging for one-dimensional nanoparticle systems. In this study, we investigate the packing behavior of one-dimensional nanoparticles of different diameters into a hexagonally packed cylindrical micellar system and demonstrate that binary one-dimensional nanoparticle superlattices of two different symmetries can be obtained by tuning particle diameter and mixing ratios. The hexagonal arrays of one-dimensional nanoparticles are embedded in the honeycomb lattices (for AB 2 type) or kagome lattices (for AB 3 type) of micellar cylinders. The maximization of free volume entropy is considered as the main driving force for the formation of superlattices, which is well supported by our theoretical free energy calculations. Our approach provides a route for fabricating binary one-dimensional nanoparticle superlattices and may be applicable for inorganic one-dimensional nanoparticle systems.Binary mixtures of 1D particles are rarely observed to cooperatively self-assemble into binary superlattices, as the particle types separate into phases. Here, the authors design a system that avoids phase separation, obtaining binary superlattices with different symmetries by simply tuning the particle diameter and mixture composition.

Binding Preferences of Amino Acids for Gold Nanoparticles: A Molecular Simulation Study.

PubMed

Shao, Qing; Hall, Carol K

2016-08-09

A better understanding of the binding preference of amino acids for gold nanoparticles of different diameters could aid in the design of peptides that bind specifically to nanoparticles of a given diameter. Here we identify the binding preference of 19 natural amino acids for three gold nanoparticles with diameters of 1.0, 2.0, and 4.0 nm, and investigate the mechanisms that govern these preferences. We calculate potentials of mean force between 36 entities (19 amino acids and 17 side chains) and the three gold nanoparticles in explicit water using well-tempered metadynamics simulations. Comparing these potentials of mean force determines the amino acids' nanoparticle binding preferences and if these preferences are controlled by the backbone, the side chain, or both. Twelve amino acids prefer to bind to the 4.0 nm gold nanoparticle, and seven prefer to bind to the 2.0 nm one. We also use atomistic molecular dynamics simulations to investigate how water molecules near the nanoparticle influence the binding of the amino acids. The solvation shells of the larger nanoparticles have higher water densities than those of the smaller nanoparticles while the orientation distributions of the water molecules in the shells of all three nanoparticles are similar. The nanoparticle preferences of the amino acids depend on whether their binding free energy is determined mainly by their ability to replace or to reorient water molecules in the nanoparticle solvation shell. The amino acids whose binding free energy depends mainly on the replacement of water molecules are likely to prefer to bind to the largest nanoparticle and tend to have relatively simple side chain structures. Those whose binding free energy depends mainly on their ability to reorient water molecules prefer a smaller nanoparticle and tend to have more complex side chain structures.

Continual model of magnetic dynamics for antiferromagnetic particles in analyzing size effects on Morin transition in hematite nanoparticles

NASA Astrophysics Data System (ADS)

Mishchenko, I.; Chuev, M.; Kubrin, S.; Lastovina, T.; Polyakov, V.; Soldatov, A.

2018-05-01

Alternative explanation to the effect of disappearance of the Morin transition on hematite nanoparticles with their size decreasing is proposed basing on an idea of the predominant role of the shape anisotropy for nanosize particles. Three types of the magnetic structure of hematite nanoparticles with various sizes are found by Mössbauer spectroscopy: coexistence of the well-pronounced antiferromagnetic and weakly ferromagnetic phases for particles with average diameters of about 55 nm, non-uniform distribution of the magnetization axes which concentrate on the vicinity of the basal plane (111) for prolonged particles with cross sections of about 20 nm, and uniform distribution of the easy axes in regard to the crystalline directions for 3-nm particles. Description of the temperature evolution of experimental data within novel model of the magnetic dynamics for antiferromagnetic particles which accounts the exchange, relativistic, and anisotropy interactions is provided, and the structural as well as energy characteristics of the studied systems are reconstructed.

On the synthesis and magnetic properties of multiwall carbon nanotube-superparamagnetic iron oxide nanoparticle nanocomposites.

PubMed

Narayanan, T N; Mary, A P Reena; Shaijumon, M M; Ci, Lijie; Ajayan, P M; Anantharaman, M R

2009-02-04

Multiwall carbon nanotubes (MWCNTs) possessing an average inner diameter of 150 nm were synthesized by template assisted chemical vapor deposition over an alumina template. Aqueous ferrofluid based on superparamagnetic iron oxide nanoparticles (SPIONs) was prepared by a controlled co-precipitation technique, and this ferrofluid was used to fill the MWCNTs by nanocapillarity. The filling of nanotubes with iron oxide nanoparticles was confirmed by electron microscopy. Selected area electron diffraction indicated the presence of iron oxide and graphitic carbon from MWCNTs. The magnetic phase transition during cooling of the MWCNT-SPION composite was investigated by low temperature magnetization studies and zero field cooled (ZFC) and field cooled experiments. The ZFC curve exhibited a blocking at approximately 110 K. A peculiar ferromagnetic ordering exhibited by the MWCNT-SPION composite above room temperature is because of the ferromagnetic interaction emanating from the clustering of superparamagnetic particles in the constrained volume of an MWCNT. This kind of MWCNT-SPION composite can be envisaged as a good agent for various biomedical applications.

Encapsulation of ascorbyl palmitate in chitosan nanoparticles by oil-in-water emulsion and ionic gelation processes.

PubMed

Yoksan, Rangrong; Jirawutthiwongchai, Jatesuda; Arpo, Kridsada

2010-03-01

The encapsulation of ascorbyl palmitate (AP) in chitosan particles was carried out by droplet formation via an oil-in-water emulsion, followed by droplet solidification via ionic gelation using sodium triphosphate pentabasic (TPP) as a cross-linking agent. The success of AP encapsulation was confirmed by FT-IR, UV-vis spectrophotometry, TGA, and XRD techniques. The obtained AP-loaded chitosan particles were spherical in shape with an average diameter of 30-100nm as observed by SEM and TEM. Loading capacity (LC) and encapsulation efficiency (EE) of AP in the nanoparticles were about 8-20% and 39-77%, respectively, when the initial AP concentration was in the range of 25-150% (w/w) of chitosan. Augmentation of the initial AP concentration led to an increase of LC and a reduction of EE. The amount of AP released from the nanoparticles in ethanol and tris buffer (pH approximately 8.0) increased with increasing LC and decreasing TPP concentration.

Thermo-responsive human α-elastin self-assembled nanoparticles for protein delivery.

PubMed

Kim, Jae Dong; Jung, Youn Jae; Woo, Chang Hee; Choi, Young Chan; Choi, Ji Suk; Cho, Yong Woo

2017-01-01

Self-assembled nanoparticles based on PEGylated human α-elastin were prepared as a potential vehicle for sustained protein delivery. The α-elastin was extracted from human adipose tissue and modified with methoxypolyethyleneglycol (mPEG) to control particle size and enhance the colloidal stability. The PEGylated human α-elastin showed sol-to-particle transition with a lower critical solution temperature (LCST) of 25°C-40°C in aqueous media. The PEGylated human α-elastin nanoparticles (PhENPs) showed a narrow size distribution with an average diameter of 330±33nm and were able to encapsulate significant amounts of insulin and bovine serum albumin (BSA) upon simple mixing at low temperature in water and subsequent heating to physiological temperature. The release profiles of insulin and BSA showed sustained release for 72h. Overall, the thermo-responsive self-assembled PhENPs provide a useful tool for a range of protein delivery and tissue engineering applications. Copyright © 2016 Elsevier B.V. All rights reserved.

Dark solitons in erbium-doped fiber lasers based on indium tin oxide as saturable absorbers

NASA Astrophysics Data System (ADS)

Guo, Jia; Zhang, Huanian; Li, Zhen; Sheng, Yingqiang; Guo, Quanxin; Han, Xile; Liu, Yanjun; Man, Baoyuan; Ning, Tingyin; Jiang, Shouzhen

2018-04-01

Dark solitons, which have good stability, long transmission distance and strong anti-interference ability. By using a coprecipitation method, the high quality indium tin oxide (ITO) were prepared with an average diameter of 34.1 nm. We used a typical Z-scan scheme involving a balanced twin-detector measurement system to investigated nonlinear optical properties of the ITO nanoparticles. The saturation intensity and modulation depths are 13.21 MW/cm2 and 0.48%, respectively. In an erbium-doped fiber (EDF) lasers, we using the ITO nanoparticles as saturable absorber (SA), and the formation of dark soliton is experimentally demonstrated. The generated dark solitons are centered at the wavelength of 1561.1 nm with a repetition rate of 22.06 MHz. Besides, the pulse width and pulse-to-pulse interval of the dark solitons is ∼1.33ns and 45.11 ns, respectively. These results indicate that the ITO nanoparticles is a promising nanomaterial for ultrafast photonics.

Reproducible fabrication of stable small nano Pt with high activity for sensor applications.

PubMed

Ye, Pingping; Guo, Xiaoyu; Liu, Guiting; Chen, Huifen; Pan, Yuxia; Wen, Ying; Yang, Haifeng

2013-07-26

Pt nanoparticles with an average size of 2-3 nm in diameter were reproducibly synthesized by reduction of H₂PtCl₆ solution containing inositol hexaphosphate (IP₆) as the stabilizing agent. Single crystals with Pt(111) faces of the resulting cubic nanoparticles were revealed by the electron diffraction pattern. The PtNPs-IP₆ nanoparticles were used to modify an electrode as a nonenzymatic sensor for H₂O₂ detection, exhibiting a fast response and high sensitivity. A low detection limit of 2.0 × 10⁻⁷ M (S/N = 3) with two linear ranges between 2.4 × 10⁻⁷ and 1.3 × 10⁻³ M (R² = 0.9987) and between 1.3 × 10⁻³ and 1.3 × 10⁻² M (R² = 0.9980) was achieved. The attractive electrochemical performance of PtNPs-IP₆ enables it to be employed as a promising material for the development of Pt-based analytical systems and other applications.

Lippia javanica: a cheap natural source for the synthesis of antibacterial silver nanocolloid

NASA Astrophysics Data System (ADS)

Kumar, Santosh; Singh, Mukesh; Halder, Dipankar; Mitra, Atanu

2016-10-01

Aqueous silver nanocolloid was synthesized in a single step by a biogenic approach using aqueous leaf extract of Lippia javanica plant which acts as both reducing as well as capping agent. The as-synthesized silver nanoparticles were characterized by UV-visible absorption spectroscopy, high-resolution transmission electron microscopy and Fourier transform infrared spectroscopy (FTIR). The UV-Vis absorption spectra of colloidal silver nanoparticles showed characteristic surface plasmon resonance peak centered at a wavelength of 415 nm. The kinetic study showed that the reduction process was complete within 2 h of time. The TEM analysis showed that most of the particles were spherical in shape and their average diameter was about 17.5 nm. FTIR study confirmed the presence of some organic functional groups in leaf extract and their participation during the reduction as well as stabilization process. In addition, the as-synthesized silver nanoparticles showed antimicrobial activity against clinically isolated pathogenic strain of E. coli and B. subtilis.

Gold Functionalized Mesoporous Silica Nanoparticle Mediated Protein and DNA Codelivery to Plant Cells Via the Biolistic Method

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

Martin-Ortigosa, Susana; Valenstein, Justin S.; Lin, Victor S.-Y.

2012-09-11

The synthesis and characterization of a gold nanoparticle functionalized mesoporous silica nanoparticle (Au-MSN) platform for codelivery of proteins and plasmid DNA to plant tissues using a biolistic particle delivery system is reported. The in vitro uptake and release profiles of fluorescently labeled bovine serum albumin (BSA) and enhanced green fluorescent protein (eGFP) are investigated. As a proof-of-concept demonstration, Au-MSN with large average pore diameters (10 nm) are shown to deliver and subsequently release proteins and plasmid DNA to the same cell after passing through the plant cell wall upon bombardment. Release of fluorescent eGFP indicates the delivery of active, non-denaturedmore » proteins to plant cells. This advance represents the first example of biolistic-mediated codelivery of proteins and plasmid DNA to plant cells via gold-functionalized MSN and provides a powerful tool for both fundamental and applied research of plant sciences.« less

Performance of SMARTer at Very Low Scattering Vector q-Range Revealed by Monodisperse Nanoparticles

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

Putra, E. Giri Rachman; Ikram, A.; Bharoto

2008-03-17

A monodisperse nanoparticle sample of polystyrene has been employed to determine performance of the 36 meter small-angle neutron scattering (SANS) BATAN spectrometer (SMARTer) at the Neutron Scattering Laboratory (NSL)--Serpong, Indonesia, in a very low scattering vector q-range. Detector position at 18 m from sample position, beam stopper of 50 mm in diameter, neutron wavelength of 5.66 A as well as 18 m-long collimator had been set up to achieve very low scattering vector q-range of SMARTer. A polydisperse smeared-spherical particle model was applied to fit the corrected small-angle scattering data of monodisperse polystyrene nanoparticle sample. The mean average of particlemore » radius of 610 A, volume fraction of 0.0026, and polydispersity of 0.1 were obtained from the fitting results. The experiment results from SMARTer are comparable to SANS-J, JAEA - Japan and it is revealed that SMARTer is powerfully able to achieve the lowest scattering vector down to 0.002 A{sup -1}.« less

Generation of polypeptide-templated gold nanoparticles using ionizing radiation.

PubMed

Walker, Candace Rae; Pushpavanam, Karthik; Nair, Divya Geetha; Potta, Thrimoorthy; Sutiyoso, Caesario; Kodibagkar, Vikram D; Sapareto, Stephen; Chang, John; Rege, Kaushal

2013-08-13

Ionizing radiation, including γ rays and X-rays, are high-energy electromagnetic radiation with diverse applications in nuclear energy, astrophysics, and medicine. In this work, we describe the use of ionizing radiation and cysteine-containing elastin-like polypeptides (C(n)ELPs, where n = 2 or 12 cysteines in the polypeptide sequence) for the generation of gold nanoparticles. In the presence of C(n)ELPs, ionizing radiation doses higher than 175 Gy resulted in the formation of maroon-colored gold nanoparticle dispersions, with maximal absorbance at 520 nm, from colorless metal salts. Visible color changes were not observed in any of the control systems, indicating that ionizing radiation, gold salt solution, and C(n)ELPs were all required for nanoparticle formation. The hydrodynamic diameters of nanoparticles, determined using dynamic light scattering, were in the range of 80-150 nm, while TEM imaging indicated the formation of gold cores 10-20 nm in diameter. Interestingly, C2ELPs formed 1-2 nm diameter gold nanoparticles in the absence of radiation. Our results describe a facile method of nanoparticle formation in which nanoparticle size can be tailored based on radiation dose and C(n)ELP type. Further improvements in these polypeptide-based systems can lead to colorimetric detection of ionizing radiation in a variety of applications.

Photoacoustic spectral characterization of perfluorocarbon droplets

NASA Astrophysics Data System (ADS)

Strohm, Eric; Gorelikov, Ivan; Matsuura, Naomi; Kolios, Michael

2012-02-01

Perfluorocarbon droplets containing optical absorbing nanoparticles have been developed for use as theranostic agents (for both imaging and therapy) and as dual-mode contrast agents. Droplets can be used as photoacoustic contrast agents, vaporized via optical irradiation, then the resulting bubbles can be used as ultrasound imaging and therapeutic agents. The photoacoustic signals from micron-sized droplets containing silica coated gold nanospheres were measured using ultra-high frequencies (100-1000 MHz). The spectra of droplets embedded in a gelatin phantom were compared to a theoretical model which calculates the pressure wave from a spherical homogenous liquid undergoing thermoelastic expansion resulting from laser absorption. The location of the spectral features of the theoretical model and experimental spectra were in agreement after accounting for increases in the droplet sound speed with frequency. The agreement between experiment and model indicate that droplets (which have negligible optical absorption in the visible and infrared spectra by themselves) emitted pressure waves related to the droplet composition and size, and was independent of the physical characteristics of the optical absorbing nanoparticles. The diameter of individual droplets was calculated using three independent methods: the time domain photoacoustic signal, the time domain pulse echo ultrasound signal, and a fit to the photoacoustic model, then compared to the diameter as measured by optical microscopy. It was found the photoacoustic and ultrasound methods calculated diameters an average of 2.6% of each other, and 8.8% lower than that measured using optical microscopy. The discrepancy between the calculated diameters and the optical measurements may be due to the difficulty in resolving the droplet edges after being embedded in the translucent gelatin medium.

Thermal Decomposition Synthesis of Iron Oxide Nanoparticles with Diminished Magnetic Dead Layer by Controlled Addition of Oxygen.

PubMed

Unni, Mythreyi; Uhl, Amanda M; Savliwala, Shehaab; Savitzky, Benjamin H; Dhavalikar, Rohan; Garraud, Nicolas; Arnold, David P; Kourkoutis, Lena F; Andrew, Jennifer S; Rinaldi, Carlos

2017-02-28

Decades of research focused on size and shape control of iron oxide nanoparticles have led to methods of synthesis that afford excellent control over physical size and shape but comparatively poor control over magnetic properties. Popular synthesis methods based on thermal decomposition of organometallic precursors in the absence of oxygen have yielded particles with mixed iron oxide phases, crystal defects, and poorer than expected magnetic properties, including the existence of a thick "magnetically dead layer" experimentally evidenced by a magnetic diameter significantly smaller than the physical diameter. Here, we show how single-crystalline iron oxide nanoparticles with few defects and similar physical and magetic diameter distributions can be obtained by introducing molecular oxygen as one of the reactive species in the thermal decomposition synthesis. This is achieved without the need for any postsynthesis oxidation or thermal annealing. These results address a significant challenge in the synthesis of nanoparticles with predictable magnetic properties and could lead to advances in applications of magnetic nanoparticles.

Synthesis of stable ZnO nanocolloids with enhanced optical limiting properties via simple solution method

NASA Astrophysics Data System (ADS)

Ramya, M.; Nideep, T. K.; Vijesh, K. R.; Nampoori, V. P. N.; Kailasnath, M.

2018-07-01

In present work, we report the synthesis of stable ZnO nanocolloids through a simple solution method which exhibit enhanced optical limiting threshold. The influences of reaction temperature on the crystal structure as well as linear and nonlinear optical properties of prepared ZnO nanoparticles were carried out. The XRD and Raman analysis reveal that the prepared ZnO nanoparticles retain the hexagonal wurtzite crystal structure. HRTEM analysis confirms the effect of reaction temperature, solvent effect on crystallinity as well as nanostructure of ZnO nanoparticles. It has been found that crystallinity and average diameter increase with reaction temperature where ethylene glycol act as both solvent and growth inhibiter. EDS spectra shows formation of pure ZnO nanoparticles. The direct energy band gap of the nanoparticles increases with decrease in particle size due to quantum confinement effect. The third order nonlinear optical properties of ZnO nanoparticles were investigated by z scan technique using a frequency doubled Nd-YAG nanosecond laser at 532 nm wavelength. The z-scan result reveals that the prepared ZnO nanoparticles exhibit self - defocusing nonlinearity. The two photon absorption coefficient and third - order nonlinear optical susceptibility increases with increasing particle size. The third-order susceptibility of the ZnO nanoparticles is found to be in the order of 10-10 esu, which is at least three order magnitude greater than the bulk ZnO. The optical limiting threshold of the nanoparticles varies in the range of 54 to 17 MW/cm2. The results suggest that ZnO nanoparticles considered as a promising candidates for the future photonic devices.

Probing plasmon resonances of individual aluminum nanoparticles

NASA Astrophysics Data System (ADS)

Wei, Zhongxia; Mao, Peng; Cao, Lu; Song, Fengqi

2018-01-01

The plasmon resonances of individual aluminum nanoparticles are investigated by electron energy-loss spectroscopy (EELS) in scanning transmission electron microscope (STEM). Surface plasmon mode and bulk plasmon mode of Al nanoparticles are clearly characterized in the EEL spectra. Discrete dipole approximation (DDA) calculations show that as the particle diameter increases from 20 nm to 100 nm, the plasmon resonance shifts to lower energy and higher mode of surface plasmon arises when the diameter reaches 60 nm and larger.

Effect of Nanoparticles on the Survival and Development of Vitrified Porcine GV Oocytes.

PubMed

Li, W J; Zhou, X L; Liu, B L; Dai, J J; Song, P; Teng, Y

BACKGROUND: Some mammalian oocytes have been successfully cryopreserved by vitrification. However, the survival and developmental rate of vitrified oocytes is still low. The incorporation of nanoparticles into cryoprotectant (CPA) may improve the efficiency of vitrification by changing the properties of solutions. The toxicity of different concentrations of hydroxy apatite (HA), silica dioxide (SO 2 ), aluminum oxide (Al 2 O 3 ) and titanium dioxide (TiO 2 ) nanoparticles (20 nm in diameter) to oocytes was tested and the toxicity threshold value of each nanoparticle was determined. Porcine GV oocytes were vitrified in optimized nano-CPA, and effects of diameter and concentration of nanoparticles on the survival rate and developmental rate of porcine GV oocytes were compared. HA nanoparticles have demonstrated the least toxicity among four nanoparticles and the developmental rate of GV-stage porcine oocytes was 100% when its concentration was lower than 0.5%. By adding 0.1% HA into VS, the developmental rate of GV-stage porcine oocytes (22%) was significantly higher than other groups. The effect of vitrification in nano-CPA on oocytes was related to the concentration of HA nanoparticles rather than their size. By adding 0.05% HA nanoparticles (60nm in diameter), the developmental rate increased dramatically from 14.7% to 30.4%. Nano-cryopreservation offers a new way to improve the effect of survival and development of oocytes, but the limitation of this technology shall not be ignored.

Evolution of silver nanoparticles in the rat lung investigated by X-ray absorption spectroscopy

DOE PAGES

Davidson, R. Andrew; Anderson, Donald S.; Van Winkle, Laura S.; ...

2014-12-16

Following a 6-h inhalation exposure to aerosolized 20 and 110 nm diameter silver nanoparticles, lung tissues from rats were investigated with X-ray absorption spectroscopy, which can identify the chemical state of silver species. Lung tissues were processed immediately after sacrifice of the animals at 0, 1, 3, and 7 days post exposure and the samples were stored in an inert and low-temperature environment until measured. We found that it is critical to follow a proper processing, storage and measurement protocol; otherwise only silver oxides are detected after inhalation even for the larger nanoparticles. The results of X-ray absorption spectroscopy measurementsmore » taken in air at 85 K suggest that the dominating silver species in all the postexposure lung tissues were metallic silver, not silver oxide, or solvated silver cations. The results further indicate that the silver nanoparticles in the tissues were transformed from the original nanoparticles to other forms of metallic silver nanomaterials and the rate of this transformation depended on the size of the original nanoparticles. Furthermore, we found that 20 nm diameter silver nanoparticles were significantly modified after aerosolization and 6-h inhalation/deposition, whereas larger, 110 nm diameter nanoparticles were largely unchanged. Over the seven-day postexposure period the smaller 20 nm silver nanoparticles underwent less change in the lung tissue than the larger 110 nm silver nanoparticles. In contrast, silica-coated gold nanoparticles did not undergo any modification processes and remained as the initial nanoparticles throughout the 7-day study period.« less

Evolution of silver nanoparticles in the rat lung investigated by X-ray absorption spectroscopy

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

Davidson, R. Andrew; Anderson, Donald S.; Van Winkle, Laura S.

Following a 6-h inhalation exposure to aerosolized 20 and 110 nm diameter silver nanoparticles, lung tissues from rats were investigated with X-ray absorption spectroscopy, which can identify the chemical state of silver species. Lung tissues were processed immediately after sacrifice of the animals at 0, 1, 3, and 7 days post exposure and the samples were stored in an inert and low-temperature environment until measured. We found that it is critical to follow a proper processing, storage and measurement protocol; otherwise only silver oxides are detected after inhalation even for the larger nanoparticles. The results of X-ray absorption spectroscopy measurementsmore » taken in air at 85 K suggest that the dominating silver species in all the postexposure lung tissues were metallic silver, not silver oxide, or solvated silver cations. The results further indicate that the silver nanoparticles in the tissues were transformed from the original nanoparticles to other forms of metallic silver nanomaterials and the rate of this transformation depended on the size of the original nanoparticles. Furthermore, we found that 20 nm diameter silver nanoparticles were significantly modified after aerosolization and 6-h inhalation/deposition, whereas larger, 110 nm diameter nanoparticles were largely unchanged. Over the seven-day postexposure period the smaller 20 nm silver nanoparticles underwent less change in the lung tissue than the larger 110 nm silver nanoparticles. In contrast, silica-coated gold nanoparticles did not undergo any modification processes and remained as the initial nanoparticles throughout the 7-day study period.« less

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

Liu, Zheng; Li, Zhilin; Institute of Carbon Fibers and Composites, Beijing University of Chemical Technology, Beijing 100029

Graphical abstract: The MWCNT/Ni-B catalyst has been successfully prepared by an electroless deposition process. The Ni-B nanoparticles on the supporter are amorphous and are well-distributed. The catalytic conversion towards hydrogenation of styrene shows excellent catalytic activity of the obtained materials. Highlights: Black-Right-Pointing-Pointer A two-step treatment of MWCNTs enabled the homogeneous growth of Ni-B nanoparticles. Black-Right-Pointing-Pointer Ni-B nanoparticles were amorphous with an average size of 60 nm. Black-Right-Pointing-Pointer There were electron transfer between Ni and B. Black-Right-Pointing-Pointer The catalyst had excellent catalytic activity towards hydrogenation of styrene. -- Abstract: Nickel-boron (Ni-B) nanoparticles supported on multi-walled carbon nanotubes (MWCNTs) were successfully synthesizedmore » through an electroless deposition process using the plating bath with sodium borohydride as a reducing agent. The structural and morphological analyses using field-emission scanning electron microscopy, X-ray diffractometry and high-resolution transmission electron microscopy have shown that the Ni-B nanoparticles deposited on the sidewalls of MWCNTs are fine spheres comprised of amorphous structure with the morphologically unique fine-structure like flowers, and homogenously dispersed with a narrow particle size distribution centered at around 60 nm diameter. The catalytic activity of MWCNT/Ni-B nanoparticles was evaluated with respect to hydrogenation of styrene. The hydrogenation catalyzed by MWCNT-supported Ni-B nanoparticles has been found to make styrene selectively converted into ethylbenzene. The highest conversion reaches 99.8% under proper reaction conditions, which demonstrates the high catalytic activity of MWCNT/Ni-B nanoparticles.« less

Oxidative stress mediated cytotoxicity of biologically synthesized silver nanoparticles in human lung epithelial adenocarcinoma cell line

NASA Astrophysics Data System (ADS)

Han, Jae Woong; Gurunathan, Sangiliyandi; Jeong, Jae-Kyo; Choi, Yun-Jung; Kwon, Deug-Nam; Park, Jin-Ki; Kim, Jin-Hoi

2014-09-01

The goal of the present study was to investigate the toxicity of biologically prepared small size of silver nanoparticles in human lung epithelial adenocarcinoma cells A549. Herein, we describe a facile method for the synthesis of silver nanoparticles by treating the supernatant from a culture of Escherichia coli with silver nitrate . The formation of silver nanoparticles was characterized using various analytical techniques. The results from UV-visible (UV-vis) spectroscopy and X-ray diffraction analysis show a characteristic strong resonance centered at 420 nm and a single crystalline nature, respectively. Fourier transform infrared spectroscopy confirmed the possible bio-molecules responsible for the reduction of silver from silver nitrate into nanoparticles. The particle size analyzer and transmission electron microscopy results suggest that silver nanoparticles are spherical in shape with an average diameter of 15 nm. The results derived from in vitro studies showed a concentration-dependent decrease in cell viability when A549 cells were exposed to silver nanoparticles. This decrease in cell viability corresponded to increased leakage of lactate dehydrogenase (LDH), increased intracellular reactive oxygen species generation (ROS), and decreased mitochondrial transmembrane potential (MTP). Furthermore, uptake and intracellular localization of silver nanoparticles were observed and were accompanied by accumulation of autophagosomes and autolysosomes in A549 cells. The results indicate that silver nanoparticles play a significant role in apoptosis. Interestingly, biologically synthesized silver nanoparticles showed more potent cytotoxicity at the concentrations tested compared to that shown by chemically synthesized silver nanoparticles. Therefore, our results demonstrated that human lung epithelial A549 cells could provide a valuable model to assess the cytotoxicity of silver nanoparticles.

Oxidative stress mediated cytotoxicity of biologically synthesized silver nanoparticles in human lung epithelial adenocarcinoma cell line

PubMed Central

2014-01-01

The goal of the present study was to investigate the toxicity of biologically prepared small size of silver nanoparticles in human lung epithelial adenocarcinoma cells A549. Herein, we describe a facile method for the synthesis of silver nanoparticles by treating the supernatant from a culture of Escherichia coli with silver nitrate. The formation of silver nanoparticles was characterized using various analytical techniques. The results from UV-visible (UV-vis) spectroscopy and X-ray diffraction analysis show a characteristic strong resonance centered at 420 nm and a single crystalline nature, respectively. Fourier transform infrared spectroscopy confirmed the possible bio-molecules responsible for the reduction of silver from silver nitrate into nanoparticles. The particle size analyzer and transmission electron microscopy results suggest that silver nanoparticles are spherical in shape with an average diameter of 15 nm. The results derived from in vitro studies showed a concentration-dependent decrease in cell viability when A549 cells were exposed to silver nanoparticles. This decrease in cell viability corresponded to increased leakage of lactate dehydrogenase (LDH), increased intracellular reactive oxygen species generation (ROS), and decreased mitochondrial transmembrane potential (MTP). Furthermore, uptake and intracellular localization of silver nanoparticles were observed and were accompanied by accumulation of autophagosomes and autolysosomes in A549 cells. The results indicate that silver nanoparticles play a significant role in apoptosis. Interestingly, biologically synthesized silver nanoparticles showed more potent cytotoxicity at the concentrations tested compared to that shown by chemically synthesized silver nanoparticles. Therefore, our results demonstrated that human lung epithelial A549 cells could provide a valuable model to assess the cytotoxicity of silver nanoparticles. PMID:25242904

Low-temperature synthesis of single-walled carbon nanotubes with a narrow diameter distribution using size-classified catalyst nanoparticles

NASA Astrophysics Data System (ADS)

Kondo, Daiyu; Sato, Shintaro; Awano, Yuji

2006-05-01

Single-walled carbon nanotubes (SWNTs) with a narrow diameter distribution have been synthesized by hot-filament chemical vapor deposition using acetylene at 590 °C. Iron nanoparticles with diameters of 1.6, 2.0, 2.5, 5.0 and 10 nm (standard deviation: ≈10%) obtained with a differential mobility analyzer were used as a catalyst without any supporting materials on a substrate. SWNTs were obtained from 2.0 nm or smaller particles. The ratio of G band to D band in Raman spectra was as high as 35 without purification, indicating that high-quality SWNTs were synthesized. The SWNT diameters correlated with the particle diameters, demonstrating diameter-controlled SWNT growth.

Evolution of the magnetic properties of Co10Cu90 nanoparticles prepared by wet chemistry with thermal annealing.

PubMed

García, I; Echeberria, J; Kakazei, G N; Golub, V O; Saliuk, O Y; Ilyn, M; Guslienko, K Y; González, J M

2012-09-01

Nanoparticles of Co10Cu90 alloy have been prepared by sonochemical wet method. According to transmission electron microscopy, bimetallic particles with typical diameter of 50-100 nm consisting of nanocrystallites with average diameter of 15-20 nm were obtained. The samples were annealed at 300 degrees C and 450 degrees C. Zero field cooled and field cooled temperature dependences of magnetization in the temperature range of 5-400 K at 50 Oe, as well as magnetization hysteresis loops at 15, 100 and 305 K were measured by vibrating sample magnetometry. Presence of antiferromagnetic phase, most probably of the oxide Co3O4, was observed in as-prepared sample. The lowest coercivity was found for the CoCu sample annealed at-300 degrees C, whereas for as prepared sample and the one annealed at 450 degrees C it was significantly higher. The samples were additionally probed by continuous wave ferromagnetic resonance at room, temperature using a standard X-band electron spin resonance spectrometer. A good correspondence between evolution of the coercivity and the microwave resonance fields with annealing temperature was observed.

Aerobic method for the synthesis of nearly size-monodisperse bismuth nanoparticles from a redox non-innocent precursor

NASA Astrophysics Data System (ADS)

Winter, H.; Christopher-Allison, E.; Brown, A. L.; Goforth, A. M.

2018-04-01

Herein, we report an aerobic synthesis method to produce bismuth nanoparticles (Bi NPs) with average diameters in the range 40-80 nm using commercially available bismuth triiodide (BiI3) as the starting material; the method uses only readily available chemicals and conventional laboratory equipment. Furthermore, size data from replicates of the synthesis under standard reaction conditions indicate that this method is highly reproducible in achieving Bi NP populations with low standard deviations in the mean diameters. We also investigated the mechanism of the reaction, which we determined results from the reduction of a soluble alkylammonium iodobismuthate precursor species formed in situ. Under appropriate concentration conditions of iodobismuthate anion, we demonstrate that burst nucleation of Bi NPs results from reduction of Bi3+ by the coordinated, redox non-innocent iodide ligands when a threshold temperature is exceeded. Finally, we demonstrate phase transfer and silica coating of the Bi NPs, which results in stable aqueous colloids with retention of size, morphology, and colloidal stability. The resultant, high atomic number, hydrophilic Bi NPs prepared using this synthesis method have potential for application in emerging x-ray contrast and x-ray therapeutic applications.

Many Body Effects on Particle Diffusion in Polymer Nanocomposites

NASA Astrophysics Data System (ADS)

Dell, Zachary E.; Schweizer, Kenneth S.

2014-03-01

Recent statistical mechanical theories of nanoparticle motion in polymer melts and networks have focused on the dilute particle limit. By combining PRISM theory predictions for microscopic structural correlations, and a new formulation of self-consistent dynamical mode coupling theory, we extend dilute theories to finite filler loading. As a minimalist model, the polymer dynamics are first assumed to be unperturbed by the presence of the nanoparticles. The long time particle diffusivity in unentangled and entangled melts is determined as a function of polymer tube diameter and radius of gyration, nanoparticle diameter, and polymer-filler attraction strength under both constant volume and constant pressure situations. The influence of nanocomposite statistical structure (depletion, steric stabilization, bridging) on dynamics is also investigated. Using recent theoretical developments for predicting tube diameters in nanocomposites, the consequences of filler-induced tube dilation on nanoparticle motion is established. In entangled melts, increasing filler loading first modestly speeds up diffusion, and then dramatically when the inter-filler separation becomes smaller than the tube diameter. At very high loadings, a filler glass transition is generically predicted.

Nanoparticle flotation collectors--the influence of particle softness.

PubMed

Yang, Songtao; Razavizadeh, Bi Bi Marzieh; Pelton, Robert; Bruin, Gerard

2013-06-12

The ability of polymeric nanoparticles to promote glass bead and pentlandite (Pn, nickel sulfide mineral) attachment to air bubbles in flotation was measured as a function of the nanoparticle glass transition temperature using six types of nanoparticles based on styrene/N-butylacrylate copolymers. Nanoparticle size, surface charge density, and hydrophobicity were approximately constant over the series. The ability of the nanoparticles to promote air bubble attachment and perform as flotation collectors was significantly greater for softer nanoparticles. We propose that softer nanoparticles were more firmly attached to the glass beads or mineral surface because the softer particles had a greater glass/polymer contact areas and thus stronger overall adhesion. The diameters of the contact areas between polymeric nanoparticles and glass surfaces were estimated with the Young-Laplace equation for soft, liquidlike particles, whereas JKR adhesion theory was applied to the harder polystyrene particles. The diameters of the contact areas were estimated to be more than an order of magnitude greater for the soft particles compared to harder polystyrene particles.

Curcumin-containing chitosan nanoparticles as a potential mucoadhesive delivery system to the colon.

PubMed

Chuah, Lay Hong; Billa, Nashiru; Roberts, Clive J; Burley, Jonathan C; Manickam, Sivakumar

2013-01-01

In the present study, we investigate the mucoadhesive characteristics and release of the anticancer agent curcumin, contained in chitosan nanoparticles (CS-NPs). Such a system has potential therapeutic benefits in the treatment of colon cancer through prolonged retention and delivery. The CS-NPs were ionically gelled with tripolyphosphate (TPP) and registered an isoelectric pH of 6.2 (z-average diameter of 214 nm ± 1.0 nm). pH variations around the isoelectric point caused a reduction in CS-NPs electrical charge which correspondingly increased the z-average due to agglomeration. Curcumin release from CS-NPs was slowest at chitosan to TPP weight ratio of 3:1, with a significant retention (36%) at the end of 6 h. Adsorption isotherms of mucin on CS-NPs fitted both the Freundlich and Langmuir models, suggesting a monolayer-limited adsorption on heterogeneous sites with varied affinities. Encapsulated curcumin exerted an influence on the adsorption of mucin due to H-bonding as well as π-π interactions between the phenolic moieties of curcumin and mucin.

Viscosity, density, and thermal conductivity of aluminum oxide and zinc oxide nanolubricants

PubMed Central

Kedzierski, M.A.; Brignoli, R.; Quine, K.T.; Brown, J.S.

2017-01-01

This paper presents liquid kinematic viscosity, density, and thermal conductivity measurements of eleven different synthetic polyolester-based nanoparticle nanolubricants (dispersions) at atmospheric pressure over the temperature range 288 K to 318 K. Aluminum oxide (Al2O3) and zinc oxide (ZnO) nanoparticles with nominal diameters of 127 nm and 135 nm, respectively, were investigated. A good dispersion of the spherical and non-spherical nanoparticles in the lubricant was maintained with a surfactant. Viscosity, density, and thermal conductivity measurements were made for the neat lubricant along with eleven nanolubricants with differing nanoparticle and surfactant mass fractions. Existing models were used to predict kinematic viscosity (±20%), thermal conductivity (±1%), and specific volume (±6%) of the nanolubricant as a function of temperature, nanoparticle mass fraction, surfactant mass fraction, and nanoparticle diameter. The liquid viscosity, density and thermal conductivity were shown to increase with respect to increasing nanoparticle mass fraction. PMID:28736463

Nickel-Salen supported paramagnetic nanoparticles for 6-His-target recombinant protein affinity purification.

PubMed

Rashid, Zahra; Ghahremanzadeh, Ramin; Nejadmoghaddam, Mohammad-Reza; Nazari, Mahboobeh; Shokri, Mohammad-Reza; Naeimi, Hossein; Zarnani, Amir-Hassan

2017-03-24

In this research, a simple, efficient, inexpensive, rapid and high yield method for the purification of 6×histidine-tagged recombinant protein was developed. For this purpose, manganese ferrite magnetic nanoparticles (MNPs) were synthesized through a co-precipitation method and then they were conveniently surface-modified with tetraethyl orthosilicate (TEOS) in order to prevent oxidation and form high density of hydroxyl groups. Next, the salen ligand was prepared from condensation reaction of salicylaldehyde and 3-aminopropyl (trimethoxy) silane (APTMS) in 1:1 molar ratio; followed by complexation with Ni(OAc) 2 .4H 2 O. Finally, the prepared Ni(II)-salen complex conjugated to silica coated MNPs and MnFe 2 O 4 @SiO 2 @Ni-Salen complex nanoparticles were obtained. The functionalized nanoparticles were spherical with an average diameter around 70nm. The obtained MNPs had a saturation magnetization about 54 emu/g and had super paramagnetic character. These MNPs were used efficiently to enrich recombinant histidine-tagged (His-tagged) protein-A from bacterial cell lysate. In about 45min, highly pure His-tagged recombinant protein was obtained, as judged by SDS-PAGE analysis and silver staining. The amount of target protein in flow through and washing fractions was minimal denoting the high efficiency of purification process. The average capacity of the matrix was found to be high and about 180±15mgg -1 (protein/MnFe 2 O 4 @SiO 2 @Ni-Salen complex). Collectively, purification process with MnFe 2 O 4 @SiO 2 @Ni-Salen complex nanoparticles is rapid, efficient, selective and whole purification can be carried out in only a single tube without the need for expensive systems. Copyright © 2017 Elsevier B.V. All rights reserved.

Cutaneous penetration of soft nanoparticles via photodamaged skin: Lipid-based and polymer-based nanocarriers for drug delivery.

PubMed

Hung, Chi-Feng; Chen, Wei-Yu; Hsu, Ching-Yun; Aljuffali, Ibrahim A; Shih, Hui-Chi; Fang, Jia-You

2015-08-01

Photoaging is recognized as the factor damaging skin-barrier function. The aim of this study was to examine the impact of ultraviolet (UV) irradiation on the cutaneous penetration of soft nanoparticles, including nanostructured lipid carriers (NLCs) and poly(lactic-co-glycolic acid) polymer nanoparticles (PNs). In vitro cutaneous permeation of retinoic acid (RA) carried by nanoparticles was evaluated. In vivo nude mouse skin distribution of topically applied nanoparticles was observed by fluorescence and confocal microscopies. The association of nanoparticles with cultured keratinocytes was measured by flow cytometry and fluorescence microscopy. The average diameter and surface charge were 236nm and -32mV for NLCs, and 207nm and -12mV for PNs. The ultrastructural images of skin demonstrated that the application of UV produced a loss of Odland bodies and desmosomes, the organelles regulating skin-barrier function. UVA exposure increased skin deposition of RA regardless of nanoparticle formulation. UVB did not alter RA deposition from nanoparticles as compared to the non-treated group. Exposure to UVA promoted RA delivery into hair follicles from NLCs and PNs by 4.2- and 4.9-fold, respectively. The in vivo skin distribution also showed a large accumulation of Nile red-loaded nanoparticles in follicles after UVA treatment. The soft nanoparticles were observed deep in the dermis. PNs with higher lipophilicity showed a greater association with keratinocytes compared to NLCs. The cell association of PNs was increased by UVA application, whereas the association between NLCs and keratinocytes was reduced two times by UVA. It was concluded that both follicles and intercellular spaces were the main pathways for nanoparticle diffusion into photodamaged skin. Copyright © 2015 Elsevier B.V. All rights reserved.

Ethylene glycol monolayer protected nanoparticles: synthesis, characterization, and interactions with biological molecules.

PubMed

Zheng, Ming; Li, Zhigang; Huang, Xueying

2004-05-11

The usefulness of the hybrid materials of nanoparticles and biological molecules on many occasions depends on how well one can achieve a rational design based on specific binding and programmable assembly. Nonspecific binding between nanoparticles and biomolecules is one of the major barriers for achieving their utilities in a biological system. In this paper, we demonstrate a new approach to eliminate nonspecific interactions between nanoparticles and biological molecules by shielding the nanoparticle with a monolayer of ethylene glycol. A direct synthesis of di-, tri-, and tetra(ethylene glycol)-protected gold nanoparticles (Au-S-EGn, n = 2, 3, and 4) was achieved under the condition that the water content was optimized in the range of 9-18% in the reaction mixture. With controlled ratio of [HAuCl4]/[EGn-SH] at 2, the synthesized particles have an average diameter of 3.5 nm and a surface plasma resonance band around 510 nm. Their surface structures were confirmed by 1H NMR spectra. These gold nanoparticles are bonded with a uniform monolayer with defined lengths of 0.8, 1.2, and 1.6 nm for Au-S-EG2, Au-S-EG3, and Au-S-EG4, respectively. They have great stabilities in aqueous solutions with a high concentration of electrolytes as well as in organic solvents. Thermogravimetric analysis revealed that the ethylene glycol monolayer coating is ca. 14% of the total nanoparticle weight. Biological binding tests by using ion-exchange chromatography and gel electrophoresis demonstrated that these Au-S-EGn (n = 2, 3, or 4) nanoparticles are free of any nonspecific bindings with various proteins, DNA, and RNA. These types of nanoparticles provide a fundamental starting material for designing hybrid materials composed of metallic nanoparticles and biomolecules.

IgA response and protection following nasal vaccination of chickens with Newcastle disease virus DNA vaccine nanoencapsulated with Ag@SiO2 hollow nanoparticles

PubMed Central

Zhao, Kai; Rong, Guangyu; Hao, Yan; Yu, Lu; Kang, Hong; Wang, Xin; Wang, Xiaohua; Jin, Zheng; Ren, Zhiyu; Li, Zejun

2016-01-01

Newcastle disease caused by ND virus (NDV) is a highly contagious disease of birds. Vaccine for effective protection of poultry animals from NDV infection is urgently needed. Mucosal immunity plays a very important role in the antiviral immune response. In this study, a NDV F gene-containing DNA vaccine encapsulated in Ag@SiO2 hollow nanoparticles (pFDNA-Ag@SiO2-NPs) with an average diameter of 500 nm were prepared to assess the mucosal immune response. These nanoparticles exhibited low cytotoxicity and did not destroy the bioactivity of plasmid DNA, which could be expressed in vitro. The plasmid DNA was sustainably released after an initial burst release. In vivo immunization showed that the intranasal immunization of chickens with pFDNA-Ag@SiO2-NPs induced high titers of serum antibody, significantly promoted lymphocyte proliferation and induced higher expression levels of IL-2 and IFN-γ in a dose-dependent manner. These results indicated that the Ag@SiO2 hollow nanoparticles could serve as an efficient and safe delivery carrier for NDV DNA vaccine to induce mucosal immunity. This study has provided promising results for the further development of mucosal vaccines encapsulated in inorganic nanoparticles. PMID:27170532

Formation and nitrile hydrogenation performance of Ru nanoparticles on a K-doped Al2O3 surface.

PubMed

Muratsugu, Satoshi; Kityakarn, Sutasinee; Wang, Fei; Ishiguro, Nozomu; Kamachi, Takashi; Yoshizawa, Kazunari; Sekizawa, Oki; Uruga, Tomoya; Tada, Mizuki

2015-10-14

Decarbonylation-promoted Ru nanoparticle formation from Ru3(CO)12 on a basic K-doped Al2O3 surface was investigated by in situ FT-IR and in situ XAFS. Supported Ru3(CO)12 clusters on K-doped Al2O3 were converted stepwise to Ru nanoparticles, which catalyzed the selective hydrogenation of nitriles to the corresponding primary amines via initial decarbonylation, the nucleation of the Ru cluster core, and the growth of metallic Ru nanoparticles on the surface. As a result, small Ru nanoparticles, with an average diameter of less than 2 nm, were formed on the support and acted as efficient catalysts for nitrile hydrogenation at 343 K under hydrogen at atmospheric pressure. The structure and catalytic performance of Ru catalysts depended strongly on the type of oxide support, and the K-doped Al2O3 support acted as a good oxide for the selective nitrile hydrogenation without basic additives like ammonia. The activation of nitriles on the modelled Ru catalyst was also investigated by DFT calculations, and the adsorption structure of a nitrene-like intermediate, which was favourable for high primary amine selectivity, was the most stable structure on Ru compared with other intermediate structures.

IgA response and protection following nasal vaccination of chickens with Newcastle disease virus DNA vaccine nanoencapsulated with Ag@SiO2 hollow nanoparticles

NASA Astrophysics Data System (ADS)

Zhao, Kai; Rong, Guangyu; Hao, Yan; Yu, Lu; Kang, Hong; Wang, Xin; Wang, Xiaohua; Jin, Zheng; Ren, Zhiyu; Li, Zejun

2016-05-01

Newcastle disease caused by ND virus (NDV) is a highly contagious disease of birds. Vaccine for effective protection of poultry animals from NDV infection is urgently needed. Mucosal immunity plays a very important role in the antiviral immune response. In this study, a NDV F gene-containing DNA vaccine encapsulated in Ag@SiO2 hollow nanoparticles (pFDNA-Ag@SiO2-NPs) with an average diameter of 500 nm were prepared to assess the mucosal immune response. These nanoparticles exhibited low cytotoxicity and did not destroy the bioactivity of plasmid DNA, which could be expressed in vitro. The plasmid DNA was sustainably released after an initial burst release. In vivo immunization showed that the intranasal immunization of chickens with pFDNA-Ag@SiO2-NPs induced high titers of serum antibody, significantly promoted lymphocyte proliferation and induced higher expression levels of IL-2 and IFN-γ in a dose-dependent manner. These results indicated that the Ag@SiO2 hollow nanoparticles could serve as an efficient and safe delivery carrier for NDV DNA vaccine to induce mucosal immunity. This study has provided promising results for the further development of mucosal vaccines encapsulated in inorganic nanoparticles.

Facile synthesis of titanium (IV) ion immobilized adenosine triphosphate functionalized silica nanoparticles for highly specific enrichment and analysis of intact phosphoproteins.

PubMed

Wang, Hao; Tian, Zhixin

2018-06-06

Analysis of phosphoproteins always faces the challenge of low stoichiometry, which demands highly selective and efficient enrichment in the initial sample preparation. Here we report our synthesis of the novel titanium (IV) ion immobilized adenosine triphosphate functionalized silica nanoparticles (Ti 4+ -ATP-NPs) for efficient enrichment of intact phosphoproteins. The average diameter of Ti 4+ -ATP-NPs was about 128 nm with good dispersibility and the saturated adsorption capacity for β-casein was 1046.5 mg/g. In addition, Ti 4+ -ATP-NPs exhibited high specificity and selectivity in enriching phosphoproteins from both standard protein mixtures and complex biological samples (non-fat milk, chicken egg white and mouse heart tissue extract) as demonstrated by SDS-PAGE. Copyright © 2018 Elsevier B.V. All rights reserved.

Gel Electrophoresis of Gold-DNA Nanoconjugates

DOE PAGES

Pellegrino, T.; Sperling, R. A.; Alivisatos, A. P.; ...

2007-01-01

Gold-DNA conjugates were investigated in detail by a comprehensive gel electrophoresis study based on 1200 gels. A controlled number of single-stranded DNA of different length was attached specifically via thiol-Au bonds to phosphine-stabilized colloidal gold nanoparticles. Alternatively, the surface of the gold particles was saturated with single stranded DNA of different length either specifically via thiol-Au bonds or by nonspecific adsorption. From the experimentally determined electrophoretic mobilities, estimates for the effective diameters of the gold-DNA conjugates were derived by applying two different data treatment approaches. The first method is based on making a calibration curve for the relation between effectivemore » diameters and mobilities with gold nanoparticles of known diameter. The second method is based on Ferguson analysis which uses gold nanoparticles of known diameter as reference database. Our study shows that effective diameters derived from gel electrophoresis measurements are affected with a high error bar as the determined values strongly depend on the method of evaluation, though relative changes in size upon binding of molecules can be detected with high precision. Furthermore, in this study, the specific attachment of DNA via gold-thiol bonds to Au nanoparticles is compared to nonspecific adsorption of DNA. Also, the maximum number of DNA molecules that can be bound per particle was determined.« less

Synthesis, characterization and application of Lagerstroemia speciosa embedded magnetic nanoparticle for Cr(VI) adsorption from aqueous solution.

PubMed

Srivastava, Shalini; Agrawal, Shashi Bhushan; Mondal, Monoj Kumar

2017-05-01

Lagerstroemia speciosa bark (LB) embedded magnetic nanoparticles were prepared by co-precipitation of Fe 2+ and Fe 3+ salt solution with ammonia and LB for Cr(VI) removal from aqueous solution. The native LB, magnetic nanoparticle (MNP), L. speciosa embedded magnetic nanoparticle (MNPLB) and Cr(VI) adsorbed MNPLB particles were characterized by SEM-EDX, TEM, BET-surface area, FT-IR, XRD and TGA methods. TEM analysis confirmed nearly spherical shape of MNP with an average diameter of 8.76nm and the surface modification did not result in the phase change of MNP as established by XRD analysis, while led to the formation of secondary particles of MNPLB with diameter of 18.54nm. Characterization results revealed covalent binding between the hydroxyl group of MNP and carboxyl group of LB particles and further confirmed its physico-chemical nature favorable for Cr(VI) adsorption. The Cr(VI) adsorption on to MNPLB particle as an adsorbent was tested under different contact time, initial Cr(VI) concentration, adsorbent dose, initial pH, temperature and agitation speed. The results of the equilibrium and kinetics of adsorption were well described by Langmuir isotherm and pseudo-second-order model, respectively. The thermodynamic parameters suggest spontaneous and endothermic nature of Cr(VI) adsorption onto MNPLB. The maximum adsorption capacity for MNPLB was calculated to be 434.78mg/g and these particles even after Cr(VI) adsorption were collected effortlessly from the aqueous solution by a magnet. The desorption of Cr(VI)-adsorbed MNPLB was found to be more than 93.72% with spent MNPLB depicting eleven successive adsorption-desorption cycles. Copyright © 2016. Published by Elsevier B.V.

Green production of microalgae-based silver chloride nanoparticles with antimicrobial activity against pathogenic bacteria.

PubMed

da Silva Ferreira, Veronica; ConzFerreira, Mateus Eugenio; Lima, Luís Maurício T R; Frasés, Susana; de Souza, Wanderley; Sant'Anna, Celso

2017-02-01

Silver nanoparticles are powerful antimicrobial agents. Here, the synthesis of silver chloride nanoparticles (AgCl-NPs) was consistently evidenced from a commercially valuable microalgae species, Chlorella vulgaris. Incubation of C. vulgaris conditioned medium with AgNO 3 resulted in a medium color change to yellow/brown (with UV-vis absorbance at 415nm), indicative of silver nanoparticle formation. Energy-dispersive X-ray spectroscopy (EDS) of purified nanoparticles confirmed the presence of both silver and chlorine atoms, and X-ray diffraction (XRD) showed the typical pattern of cubic crystalline AgCl-NPs. Transmission electron microscopy (TEM) showed that most particles (65%) were spherical, with average diameter of 9.8±5.7nm. Fourier transform infrared spectroscopy (FTIR) of purified nanoparticle fractions suggested that proteins are the main molecular entities involved in AgCl-NP formation and stabilization. AgCl-NPs (from 10μg/mL) decreased by 98% the growth of Gram-positive Staphylococcus aureus and Gram-negative Klebsiella pneumoniae bacterial pathogens, and had a dose-dependent effect on cell viability, which was measured by automated image-based high content screening (HCS). Ultrastructural analysis of treated bacteria by TEM revealed the abnormal arrangement of the chromosomal DNA. Our findings strongly indicated that the AgCl-NPs from C. vulgaris conditioned medium is a promising 'green' alternative for biomedical application as antimicrobials. Copyright © 2016 Elsevier Inc. All rights reserved.

Size characterization of airborne SiO2 nanoparticles with on-line and off-line measurement techniques: an interlaboratory comparison study

NASA Astrophysics Data System (ADS)

Motzkus, C.; Macé, T.; Gaie-Levrel, F.; Ducourtieux, S.; Delvallee, A.; Dirscherl, K.; Hodoroaba, V.-D.; Popov, I.; Popov, O.; Kuselman, I.; Takahata, K.; Ehara, K.; Ausset, P.; Maillé, M.; Michielsen, N.; Bondiguel, S.; Gensdarmes, F.; Morawska, L.; Johnson, G. R.; Faghihi, E. M.; Kim, C. S.; Kim, Y. H.; Chu, M. C.; Guardado, J. A.; Salas, A.; Capannelli, G.; Costa, C.; Bostrom, T.; Jämting, Å. K.; Lawn, M. A.; Adlem, L.; Vaslin-Reimann, S.

2013-10-01

Results of an interlaboratory comparison on size characterization of SiO2 airborne nanoparticles using on-line and off-line measurement techniques are discussed. This study was performed in the framework of Technical Working Area (TWA) 34—"Properties of Nanoparticle Populations" of the Versailles Project on Advanced Materials and Standards (VAMAS) in the project no. 3 "Techniques for characterizing size distribution of airborne nanoparticles". Two types of nano-aerosols, consisting of (1) one population of nanoparticles with a mean diameter between 30.3 and 39.0 nm and (2) two populations of non-agglomerated nanoparticles with mean diameters between, respectively, 36.2-46.6 nm and 80.2-89.8 nm, were generated for characterization measurements. Scanning mobility particle size spectrometers (SMPS) were used for on-line measurements of size distributions of the produced nano-aerosols. Transmission electron microscopy, scanning electron microscopy, and atomic force microscopy were used as off-line measurement techniques for nanoparticles characterization. Samples were deposited on appropriate supports such as grids, filters, and mica plates by electrostatic precipitation and a filtration technique using SMPS controlled generation upstream. The results of the main size distribution parameters (mean and mode diameters), obtained from several laboratories, were compared based on metrological approaches including metrological traceability, calibration, and evaluation of the measurement uncertainty. Internationally harmonized measurement procedures for airborne SiO2 nanoparticles characterization are proposed.

Synthesis of mono-dispersed nanofluids using solution plasma

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

Heo, Yong Kang, E-mail: yk@rd.numse.nagoya-u.ac.jp; Bratescu, Maria Antoaneta, E-mail: maria@rd.numse.nagoya-u.ac.jp; Knowledge Hub Aichi, Yakusa-cho, Nagakute-ku, Toyota

2014-07-14

Small-sized and well-dispersed gold nanoparticles (NPs) for nanofluidics have been synthesized by electrical discharge in liquid environment using termed solution plasma processing (SPP). Electrons and the hydrogen radicals are reducing the gold ions to the neutral form in plasma gas phase and liquid phase, respectively. The gold NPs have the smallest diameter of 4.9 nm when the solution temperature was kept at 20 °C. Nucleation and growth theory describe the evolution of the NP diameter right after the reduction reaction in function of the system temperature, NP surface energy, dispersion energy barrier, and nucleation rate. Negative charges on the NPs surface duringmore » and after SPP generate repulsive forces among the NPs avoiding their agglomeration in solution. Increasing the average energy in the SPP determines a decrease of the zeta potential and an increase of the NPs diameter. An important enhancement of the thermal conductivity of 9.4% was measured for the synthesized nanofluids containing NPs with the smallest size.« less

Green Synthesis and Characterization of Silver Nanoparticles Using Citrullus lanatus Fruit Rind Extract

PubMed Central

Ndikau, Michael; Andala, Dickson M.; Masika, Eric

2017-01-01

The wide-scale application of silver nanoparticles (AgNPs) in areas such as chemical sensing, nanomedicine, and electronics has led to their increased demand. Current methods of AgNPs synthesis involve the use of hazardous reagents and toxic solvents. There is a need for the development of new methods of synthesizing AgNPs that use environmentally safe reagents and solvents. This work reports a green method where silver nanoparticles (AgNPs) were synthesized using silver nitrate and the aqueous extract of Citrullus lanatus fruit rind as the reductant and the capping agent. The optimized conditions for the AgNPs synthesis were a temperature of 80°C, pH 10, 0.001 M AgNO3, 250 g/L watermelon rind extract (WMRE), and a reactant ratio of 4 : 5 (AgNO3 to WMRE). The AgNPs were characterized by Ultraviolet-Visible (UV-Vis) spectroscopy exhibiting a λmax at 404 nm which was consistent with the spectra of spherical AgNPs within the wavelength range of 380–450 nm, and Cyclic Voltammetry (CV) results showed a distinct oxidation peak at +291 mV while the standard reference AgNPs (20 nm diameter) oxidation peak occurred at +290 mV, and Transmission Electron Microscopy (TEM) revealed spherical shaped AgNPs. The AgNPs were found to have an average diameter of 17.96 ± 0.16 nm. PMID:28316627

Identifying a size-specific hazard of silica nanoparticles after intravenous administration and its relationship to the other hazards that have negative correlations with the particle size in mice

NASA Astrophysics Data System (ADS)

Handa, Takayuki; Hirai, Toshiro; Izumi, Natsumi; Eto, Shun-ichi; Tsunoda, Shin-ichi; Nagano, Kazuya; Higashisaka, Kazuma; Yoshioka, Yasuo; Tsutsumi, Yasuo

2017-03-01

Many of the beneficial and toxic biological effects of nanoparticles have been shown to have a negative correlation with particle size. However, few studies have demonstrated biological effects that only occur at specific nanoparticle sizes. Further elucidation of the size-specific biological effects of nanoparticles may reveal not only unknown toxicities, but also novel benefits of nanoparticles. We used surface-unmodified silica particles with a wide range of diameters and narrow size intervals between the diameters (10, 30, 50, 70, 100, 300, and 1000 nm) to investigate the relationship between particle size and acute toxicity after intravenous administration in mice. Negative correlations between particle size and thrombocytopenia, liver damage, and lethal toxicity were observed. However, a specific size-effect was observed for the severity of hypothermia, where silica nanoparticles with a diameter of 50 nm induced the most severe hypothermia. Further investigation revealed that this hypothermia was mediated not by histamine, but by platelet-activating factor, and it was independent of the thrombocytopenia and the liver damage. In addition, macrophages/Kupffer cells and platelets, but not neutrophils, play a critical role in the hypothermia. The present results reveal that silica nanoparticles have particle size-specific toxicity in mice, suggesting that other types of nanoparticles may also have biological effects that only manifest at specific particle sizes. Further study of the size-specific effects of nanoparticles is essential for safer and more effective nanomedicines.

Comparative studies on Indian traditional nanomedicine Yashadha Bhasma and zinc oxide nanoparticles for anti-diabetic activity

NASA Astrophysics Data System (ADS)

Durgalakshmi, D.; Ajay Rakkesh, R.; Bhargavi Ram, T.; Balakumar, S.

2017-07-01

Diabetes mellitus is the most common endocrine disorder due to carbohydrate metabolism. Also, zinc and its supplements have been used in Indian traditional medicines for treating urinary tract infections. In this work, an attempt has been made to compare the properties of ‘Yashadha Bhasma’ a traditional ayurvedic ZnO supplement for diabetic treatment with the laboratory-synthesized ZnO nanoparticles. The nano-sized ZnO particles are synthesized using co-precipitation method and calcined at 400 °C for further purification. Confirmation of ZnO and presence of Ca and K elements additional to Zn in Yashadha Bhasma is confirmed from XPS. The morphology of ZnO is found to be spherical with average diameter of 15 nm. TEM results show that ZnO rods of Yashadha Bhasma are porous and non-uniform. Glucose degradation studies revealed good performance with ZnO nanoparticles with 80% degradation occurring within 15 min itself. Antibacterial studies also performed well establishing efficacy of ZnO nanoparticles against both gram-positive and gram-negative bacterial strains, thereby establishing suitable material for treating diabetes mellitus and also curing bacterial wound infections arising due to diabetes mellitus.

Silver nanoparticle induced cytotoxicity, oxidative stress, and DNA damage in CHO cells

NASA Astrophysics Data System (ADS)

Awasthi, Kumud Kant; Awasthi, Anjali; Kumar, Narender; Roy, Partha; Awasthi, Kamlendra; John, P. J.

2013-09-01

Silver nanoparticles (Ag NPs) are being used increasingly in wound dressings, catheters, and in various household products due to their antimicrobial activity. The present study reports the toxicity evaluation of synthesized and well characterized Ag NPs using Chinese hamster ovary (CHO) cells. The UV-Vis spectroscopy reveals the formation of silver nanoparticles by exhibiting the typical surface plasmon absorption maxima at 408-410 nm. Transmission electron microscopy (TEM) reveals that the average diameter of silver nanoparticles is about 5.0 ± 1.0 nm and that they have spherical shape. Cell visibility and cell viability percentage show dose-dependent cellular toxicity of Ag NPs. The half maximal inhibitory concentration (IC50) for CHO cells is 68.0 ± 2.65 μg/ml after 24 h Ag NPs exposure. Toxicity evaluations, including cellular morphology, mitochondrial function (MTT assay), reactive oxygen species (ROS), and DNA fragmentation assay (Ladder pattern) were assessed in unexposed CHO cells (control) and the cells exposed to Ag NPs concentrations of 15, 30, and 60 μg/ml for 24 h. The findings may assist in the designing of Ag NPs for various applications and provide insights into their toxicity.

Synthesis, structure and magnetic properties of porous magnetic composite, based on MCM-41 molecular sieve with Fe{sub 3}O{sub 4} nanoparticles

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

Kolotilov, Sergey V.; Shvets, Oleksiy; Cador, Olivier

2006-08-15

Porous magnetic composites were prepared by the synthesis of molecular sieve MCM-41 in the presence of Fe{sub 3}O{sub 4} nanoparticles with average diameter of 15 nm. Nanoparticles were captured by porous silica matrix MCM-41, which resulted in their incorporation, as it was confirmed by TEM, SEM and X-ray diffraction. The materials possessed high surface area (392-666 m{sup 2} g{sup -1}), high pore volume (0.39-0.73 cm{sup 3} g{sup -1}) along with high magnetic response (M {sub S} up to 28.4 emu g{sup -1} at 300 K). Calcination of samples resulted in partial oxidation of Fe{sub 3}O{sub 4} to {alpha}-Fe{sub 2}O{sub 3}.more » The influence of nanoparticles content on sorption and magnetic properties of the composites was shown. No hysteresis was found for the samples at 300 K; at 5 K, H {sub C} was in the range 370-385 G for non-calcinated samples and 350-356 G for calcinated ones. - Graphical abstract: Schematic presentation of MCM-41/Fe{sub 3}O{sub 4} composite.« less

Electrospinning of doxorubicin loaded silica/poly(ɛ-caprolactone) hybrid fiber mats for sustained drug release

NASA Astrophysics Data System (ADS)

El Gohary, Mohammed I.; El Hady, Bothaina M. Abd; Saeed, Aziza A. Al; Tolba, Emad; El Rashedi, Ahlam M. I.; Saleh, Safaa

2018-06-01

Loading of anticancer drugs into electrospun fiber matrices is a portentous approach for clinical treatment of diseased tissues or organs. In this study, doxorubicin hydrochloride (DOX) is added to silica nanoparticles () during the formation of via the sol-gel approach. The obtained nanoparticles are then added to poly(-caprolactone) (PCL) and poly(ethylene oxide) (PEO) blend before electrospinning process via different methods. The effects of DOX addition as a free form or as nanoparticles on physical and chemical properties of obtained PCL-PEO fibers, as well as release profiles are evaluated to give a continual DOX release for several days. The morphology observed with scanning electron microscope (FESEM) revealed significant changes in the average diameter of obtained fibers ranging from 2164 nm to 659 nm and distribution of drug-loaded nanoparticles in the final mats according to the mode of additions. With the same manner, the releasing performances of obtained mats are quite different. Therefore, fabrication of drug loaded mats would offer a powerful approach to minimize serious side effects for clinical patients and allows us to control the drug concentration in the bloodstream.

Highly monodisperse multiple twinned AuCu-Pt trimetallic nanoparticles with high index surfaces.

PubMed

Khanal, Subarna; Bhattarai, Nabraj; McMaster, David; Bahena, Daniel; Velazquez-Salazar, J Jesus; Jose-Yacaman, Miguel

2014-08-14

Trimetallic nanoparticles possess different properties than their mono- and bi-metallic counterparts, opening a wide range of possibilities for diverse potential applications with the notion to study possible morphology, atomic ordering, reduce precious metal consumption and many others. In this paper, we present a comprehensive experimental study on AuCu-Pt trimetallic nanoparticles with an average diameter of 15 ± 1.0 nm, synthesized in a one-pot synthesis method and characterized by the Cs-corrected scanning transmission electron microscopy technique that allowed us to probe the structure at the atomic level resolution. A new way to control the nanoparticle morphology by the presence of third metal (Pt) is also discussed by the overgrowth of Pt on the as prepared AuCu core by Frank-van der Merwe (FM) layer-by-layer and Stranski-Krastanov (SK) island-on-wetting-layer growth modes. With the application of this research, we are now a step closer to produce optimum catalysts in which the active phase forms only surface monolayers. In addition, the nanoalloy exhibits high index facet surfaces with {211} and {321} families that are highly open-structure surfaces and are interesting for the catalytic applications.

Highly Monodisperse Multiple Twinned AuCu/Pt Trimetallic Nanoparticles with High Index Surfaces

PubMed Central

Khanal, Subarna; Bhattarai, Nabraj; McMaster, David; Bahena, Daniel; Velazquez-Salazar, J. Jesus

2014-01-01

Trimetallic nanoparticles present different properties than their mono- and bi-metallic counterparts, opening a wide range of possibilities for diverse potential applications with the notion to study possible morphology, atomic ordering, reduce precious metal consumption and many others. In this paper, we are presenting a comprehensive experimental study on AuCu/Pt trimetallic nanoparticles with an average diameter 15 ± 1.0 nm, synthesized in one-pot synthesis method and characterized by Cs-corrected scanning transmission electron microscopy technique that allowed us to probe the structure at the atomic level resolution. A new way to control the nanoparticle morphology by the presence of third metal (Pt) is also discussed by the overgrowth of Pt on as prepared AuCu core by Frank–van der Merwe (FM) layer-by-layer and Stranski–Krastanov (SK) island-on-wetting-layer growth modes. With the application of this research, we are now a step closer to produce optimum catalysts in which the active phase forms only surface monolayers. In addition, the nanoalloy presents high index facet surfaces with {211} and {321} families, that are highly open-structure surfaces and are interesting for the catalytic applications. PMID:24975090

Room Temperature Radiolytic Synthesized Cu@CuAlO2-Al2O3 Nanoparticles

PubMed Central

Abedini, Alam; Saion, Elias; Larki, Farhad; Zakaria, Azmi; Noroozi, Monir; Soltani, Nayereh

2012-01-01

Colloidal Cu@CuAlO2-Al2O3 bimetallic nanoparticles were prepared by a gamma irradiation method in an aqueous system in the presence of polyvinyl pyrrolidone (PVP) and isopropanol respectively as a colloidal stabilizer and scavenger of hydrogen and hydroxyl radicals. The gamma irradiation was carried out in a 60Co gamma source chamber with different doses up to 120 kGy. The formation of Cu@CuAlO2-Al2O3 nanoparticles was observed initially by the change in color of the colloidal samples from colorless to brown. Fourier transform infrared spectroscopy (FTIR) confirmed the presence of bonds between polymer chains and the metal surface at all radiation doses. Results of transmission electron microscopy (TEM), energy dispersive X-ray spectrometry (EDX), and X-ray diffraction (XRD) showed that Cu@CuAlO2-Al2O3 nanoparticles are in a core-shell structure. By controlling the absorbed dose and precursor concentration, nanoclusters with different particle sizes were obtained. The average particle diameter increased with increased precursor concentration and decreased with increased dose. This is due to the competition between nucleation, growth, and aggregation processes in the formation of nanoclusters during irradiation. PMID:23109893

Room temperature radiolytic synthesized Cu@CuAlO(2)-Al(2)O(3) nanoparticles.

PubMed

Abedini, Alam; Saion, Elias; Larki, Farhad; Zakaria, Azmi; Noroozi, Monir; Soltani, Nayereh

2012-01-01

Colloidal Cu@CuAlO(2)-Al(2)O(3) bimetallic nanoparticles were prepared by a gamma irradiation method in an aqueous system in the presence of polyvinyl pyrrolidone (PVP) and isopropanol respectively as a colloidal stabilizer and scavenger of hydrogen and hydroxyl radicals. The gamma irradiation was carried out in a (60)Co gamma source chamber with different doses up to 120 kGy. The formation of Cu@CuAlO(2)-Al(2)O(3) nanoparticles was observed initially by the change in color of the colloidal samples from colorless to brown. Fourier transform infrared spectroscopy (FTIR) confirmed the presence of bonds between polymer chains and the metal surface at all radiation doses. Results of transmission electron microscopy (TEM), energy dispersive X-ray spectrometry (EDX), and X-ray diffraction (XRD) showed that Cu@CuAlO(2)-Al(2)O(3) nanoparticles are in a core-shell structure. By controlling the absorbed dose and precursor concentration, nanoclusters with different particle sizes were obtained. The average particle diameter increased with increased precursor concentration and decreased with increased dose. This is due to the competition between nucleation, growth, and aggregation processes in the formation of nanoclusters during irradiation.

Synthesis and characterization of Pd(0), PdS, and Pd-PdO core-shell nanoparticles by solventless thermolysis of a Pd-thiolate cluster

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

Jose, Deepa; Jagirdar, Balaji R., E-mail: jagirdar@ipc.iisc.ernet.i

2010-09-15

Colloids of palladium nanoparticles have been prepared by the solvated metal atom dispersion (SMAD) method. The as-prepared Pd colloid consists of particles with an average diameter of 2.8{+-}0.1 nm. Digestive ripening of the as-prepared Pd colloid, a process involving refluxing the as-prepared colloid at or near the boiling point of the solvent in the presence of a passivating agent, dodecanethiol resulted in a previously reported Pd-thiolate cluster, [Pd(SC{sub 12}H{sub 25}){sub 2}]{sub 6} but did not render the expected narrowing down of the particle size distribution. Solventless thermolysis of the Pd-thiolate complex resulted in various Pd systems such as Pd(0), PdS,more » and Pd-PdO core-shell nanoparticles thus demonstrating its versatility. These Pd nanostructures have been characterized using high-resolution electron microscopy and powder X-ray diffraction methods. - Graphical abstract: Solventless thermolysis of a single palladium-thiolate cluster affords various Pd systems such as Pd(0), Pd-PdO core-shell, and PdS nanoparticles demonstrating the versatility of the precursor and the methodology.« less

Gastrointestinal bioavailability of 2.0 nm diameter gold nanoparticles.

PubMed

Smith, Candice A; Simpson, Carrie A; Kim, Ganghyeok; Carter, Carly J; Feldheim, Daniel L

2013-05-28

The use of gold nanoparticles as imaging agents and therapeutic delivery systems is growing rapidly. However, a significant limitation of gold nanoparticles currently is their low absorption efficiencies in the gastrointestinal (GI) tract following oral administration. In an attempt to identify ligands that facilitate gold nanoparticle absorption in the GI tract, we have studied the oral bioavailability of 2.0 nm diameter gold nanoparticles modified with the small molecules p-mercaptobenzoic acid and glutathione, and polyethylene glycols (PEG) of different lengths and charge (neutral and anionic). We show that GI absorption of gold nanoparticles modified with the small molecules tested was undetectable. However, the absorption of PEGs depended upon PEG length, with the shortest PEG studied yielding gold nanoparticle absorptions that are orders-of-magnitude larger than observed previously. As the oral route is the most convenient one for administering drugs and diagnostic reagents, these results suggest that short-chain PEGs may be useful in the design of gold nanoparticles for the diagnosis and treatment of disease.

Solar light-driven photocatalysis using mixed-phase bismuth ferrite (BiFeO3/Bi25FeO40) nanoparticles for remediation of dye-contaminated water: kinetics and comparison with artificial UV and visible light-mediated photocatalysis.

PubMed

Kalikeri, Shankramma; Shetty Kodialbail, Vidya

2018-05-01

Mixed-phase bismuth ferrite (BFO) nanoparticles were prepared by co-precipitation method using potassium hydroxide as the precipitant. X-ray diffractogram (XRD) of the particles showed the formation of mixed-phase BFO nanoparticles containing BiFeO 3 /Bi 25 FeO 40 phases with the crystallite size of 70 nm. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed the formation of quasi-spherical particles. The BFO nanoparticles were uniform sized with narrow size range and with the average hydrodynamic diameter of 76 nm. The band gap energy of 2.2 eV showed its ability to absorb light even in the visible range. Water contaminated with Acid Yellow (AY-17) and Reactive Blue (RB-19) dye was treated by photocatalysis under UV, visible, and solar light irradiation using the BFO nanoparticles. The BFO nanoparticles showed maximum photocatalytical activity under solar light as compared to UV and visible irradiations, and photocatalysis was favored under acidic pH. Complete degradation of AY-17 dyes and around 95% degradation of RB-19 could be achieved under solar light at pH 5. The kinetics of degradation followed the Langmuir-Hinshelhood kinetic model showing that the heterogeneous photocatalysis is adsorption controlled. The findings of this work prove the synthesized BFO nanoparticles as promising photocatalysts for the treatment of dye-contaminated industrial wastewater.

Enhanced debromination of decabrominated diphenyl ether in aqueous solution by attapulgite supported Fe/Ni bimetallic nanoparticles: kinetics and pathways

NASA Astrophysics Data System (ADS)

Liu, Zongtang; Gu, Chenggang; Bian, Yongrong; Jiang, Xin; Sun, Yufeng; Fei, Zhenghao; Dai, Jingtao

2017-08-01

In this study, Fe/Ni bimetallic nanoparticles were supported on the attapulgite (A-Fe/Ni) to enhance the degradation reactivity of decabrominated diphenyl ether (BDE209) in aqueous solution. The Fe/Ni nanoparticles were well distributed on the attapulgite surface with an average diameter of 20-40 nm. The removal percentage of BDE209 by A-Fe/Ni was 1.59 times higher than Fe/Ni nanoparticles alone because attapulgite could act as supporting material to disperse Fe/Ni nanoparticles and prevent Fe/Ni nanoparticles from aggregation. The degradation kinetics for BDE209 debromination by A-Fe/Ni could be well described by a pseudo-first-order model, and the debromination rate constant of BDE209 increased with increasing the dosage of A-Fe/Ni, water/THF ratio, and decreasing the initial BDE209 concentration and solution pH. The degradation products were identified using a third-order polynomial regression equation between the experimental and reference gas chromatography relative retention times. Stepwise debromination from n-bromo-DE to (n  -  1)-bromo-DE was a possible pathway with bromines being substituted sequentially by hydrogen. The preferred elimination of bromines of BDE209 by A-Fe/Ni followed the debromination preference of para-Br  >  meta-Br  >  ortho-Br. The results provide evidences for understanding the debromination mechanism of polybrominated diphenyl ether by clay-supported Fe/Ni nanoparticles.

Uneven distribution of inorganic pollutants in marine air originating from ocean-going ships.

PubMed

Bencs, László; Horemans, Benjamin; Buczyńska, Anna Jolanta; Van Grieken, René

2017-03-01

The distribution of mass, water-soluble inorganic salts and mineral elements of size-segregated aerosols (PM 1 , PM 2.5-1 and PM 10-2.5 ), precursor gaseous pollutants, black carbon, and nanoparticles (10-300 nm size range) at the Southern Bight of the North Sea has been studied. The concentrations of air pollutants peaked over shipping lanes, open-water anchorage areas and frequently navigated waters, due to the presence of mobile emission sources. A considerable decrease in air pollutant levels was seen when diverting from these marine areas towards remote or coastal banks. These findings showed the rapid dispersion of pollutants in the marine air. The nano-aerosol count, originating from ocean-going ships, peaked at lower average aerodynamic diameters (e.g., ≈28 nm) than those, observed from low-displacement vessels (45-50 nm, e.g., for fishing boats). The average diameter of nano-PM depended also on weather conditions, e.g., it was higher (≈50 nm) in air of higher humidity. Copyright © 2016 Elsevier Ltd. All rights reserved.

Specific Internalisation of Gold Nanoparticles into Engineered Porous Protein Cages via Affinity Binding

PubMed Central

Peng, Tao; Free, Paul; Fernig, David G.; Lim, Sierin; Tomczak, Nikodem

2016-01-01

Porous protein cages are supramolecular protein self-assemblies presenting pores that allow the access of surrounding molecules and ions into their core in order to store and transport them in biological environments. Protein cages’ pores are attractive channels for the internalisation of inorganic nanoparticles and an alternative for the preparation of hybrid bioinspired nanoparticles. However, strategies based on nanoparticle transport through the pores are largely unexplored, due to the difficulty of tailoring nanoparticles that have diameters commensurate with the pores size and simultaneously displaying specific affinity to the cages’ core and low non-specific binding to the cages’ outer surface. We evaluated the specific internalisation of single small gold nanoparticles, 3.9 nm in diameter, into porous protein cages via affinity binding. The E2 protein cage derived from the Geobacillus stearothermophilus presents 12 pores, 6 nm in diameter, and an empty core of 13 nm in diameter. We engineered the E2 protein by site-directed mutagenesis with oligohistidine sequences exposing them into the cage’s core. Dynamic light scattering and electron microscopy analysis show that the structures of E2 protein cages mutated with bis- or penta-histidine sequences are well conserved. The surface of the gold nanoparticles was passivated with a self-assembled monolayer made of a mixture of short peptidols and thiolated alkane ethylene glycol ligands. Such monolayers are found to provide thin coatings preventing non-specific binding to proteins. Further functionalisation of the peptide coated gold nanoparticles with Ni2+ nitrilotriacetic moieties enabled the specific binding to oligohistidine tagged cages. The internalisation via affinity binding was evaluated by electron microscopy analysis. From the various mutations tested, only the penta-histidine mutated E2 protein cage showed repeatable and stable internalisation. The present work overcomes the limitations of currently available approaches and provides a new route to design tailored and well-controlled hybrid nanoparticles. PMID:27622533

Films of brookite TiO2 nanorods/nanoparticles deposited by matrix-assisted pulsed laser evaporation as NO2 gas-sensing layers

NASA Astrophysics Data System (ADS)

Caricato, A. P.; Buonsanti, R.; Catalano, M.; Cesaria, M.; Cozzoli, P. D.; Luches, A.; Manera, M. G.; Martino, M.; Taurino, A.; Rella, R.

2011-09-01

Titanium dioxide (TiO2) nanorods in the brookite phase, with average dimensions of 3-4 nm × 20-50 nm, were synthesized by a wet-chemical aminolysis route and used as precursors for thin films that were deposited by the matrix-assisted pulsed laser evaporation (MAPLE) technique. A nanorod solution in toluene (0.016 wt% TiO2) was frozen at the liquid-nitrogen temperature and irradiated with a KrF excimer laser at a fluence of 350 mJ/cm2 and repetition rate of 10 Hz. Single-crystal Si wafers, silica slides, carbon-coated Cu grids and alumina interdigitated slabs were used as substrates to allow performing different characterizations. Films fabricated with 6000 laser pulses had an average thickness of ˜150 nm, and a complete coverage of the selected substrate as achieved. High-resolution scanning and transmission electron microscopy investigations evidenced the formation of quite rough films incorporating individually distinguishable TiO2 nanorods and crystalline spherical nanoparticles with an average diameter of ˜13 nm. Spectrophotometric analysis showed high transparency through the UV-Vis spectral range. Promising resistive sensing responses to 1 ppm of NO2 mixed in dry air were obtained.

Progress toward clonable inorganic nanoparticles

NASA Astrophysics Data System (ADS)

Ni, Thomas W.; Staicu, Lucian C.; Nemeth, Richard S.; Schwartz, Cindi L.; Crawford, David; Seligman, Jeffrey D.; Hunter, William J.; Pilon-Smits, Elizabeth A. H.; Ackerson, Christopher J.

2015-10-01

Pseudomonas moraviensis stanleyae was recently isolated from the roots of the selenium (Se) hyperaccumulator plant Stanleya pinnata. This bacterium tolerates normally lethal concentrations of SeO32- in liquid culture, where it also produces Se nanoparticles. Structure and cellular ultrastructure of the Se nanoparticles as determined by cellular electron tomography shows the nanoparticles as intracellular, of narrow dispersity, symmetrically irregular and without any observable membrane or structured protein shell. Protein mass spectrometry of a fractionated soluble cytosolic material with selenite reducing capability identified nitrite reductase and glutathione reductase homologues as NADPH dependent candidate enzymes for the reduction of selenite to zerovalent Se nanoparticles. In vitro experiments with commercially sourced glutathione reductase revealed that the enzyme can reduce SeO32- (selenite) to Se nanoparticles in an NADPH-dependent process. The disappearance of the enzyme as determined by protein assay during nanoparticle formation suggests that glutathione reductase is associated with or possibly entombed in the nanoparticles whose formation it catalyzes. Chemically dissolving the nanoparticles releases the enzyme. The size of the nanoparticles varies with SeO32- concentration, varying in size form 5 nm diameter when formed at 1.0 μM [SeO32-] to 50 nm maximum diameter when formed at 100 μM [SeO32-]. In aggregate, we suggest that glutathione reductase possesses the key attributes of a clonable nanoparticle system: ion reduction, nanoparticle retention and size control of the nanoparticle at the enzyme site.Pseudomonas moraviensis stanleyae was recently isolated from the roots of the selenium (Se) hyperaccumulator plant Stanleya pinnata. This bacterium tolerates normally lethal concentrations of SeO32- in liquid culture, where it also produces Se nanoparticles. Structure and cellular ultrastructure of the Se nanoparticles as determined by cellular electron tomography shows the nanoparticles as intracellular, of narrow dispersity, symmetrically irregular and without any observable membrane or structured protein shell. Protein mass spectrometry of a fractionated soluble cytosolic material with selenite reducing capability identified nitrite reductase and glutathione reductase homologues as NADPH dependent candidate enzymes for the reduction of selenite to zerovalent Se nanoparticles. In vitro experiments with commercially sourced glutathione reductase revealed that the enzyme can reduce SeO32- (selenite) to Se nanoparticles in an NADPH-dependent process. The disappearance of the enzyme as determined by protein assay during nanoparticle formation suggests that glutathione reductase is associated with or possibly entombed in the nanoparticles whose formation it catalyzes. Chemically dissolving the nanoparticles releases the enzyme. The size of the nanoparticles varies with SeO32- concentration, varying in size form 5 nm diameter when formed at 1.0 μM [SeO32-] to 50 nm maximum diameter when formed at 100 μM [SeO32-]. In aggregate, we suggest that glutathione reductase possesses the key attributes of a clonable nanoparticle system: ion reduction, nanoparticle retention and size control of the nanoparticle at the enzyme site. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr04097c

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

Nathanael, A. Joseph; Department of Nanomaterials Engineering, Chungnam National University, Daejeon, 305-764; Mangalaraj, D., E-mail: dmraj800@yahoo.com

In this study, undoped and yttrium (Y) doped nanocrystalline hydroxyapatite crystals were synthesized by the hydrothermal method at 180 Degree-Sign C for 24 h. Highly ordered and oriented hydroxyapatite (HAp) nanorods were prepared by yttrium doping and their nanostructure and physical properties were compared with those of undoped HAp rods. FESEM images showed that the doping with Y ions reduced the diameter (from 25 nm to 15 nm) and increased the length (from 95 nm to 115 nm) of the synthesized rods. The aspect ratio of the undoped and Y-doped nanorods were calculated to be 4.303 (SD = 0.0959) andmore » 7.61 (SD = 0.0355), respectively. Specific surface area (SSA) analysis showed that SSA also increased from 66.74 m{sup 2}/g to 68.57 m{sup 2}/g with the addition of yttrium. Y-doped HAp nanorod reinforced HMWPE composites displayed the better mechanical performance than those reinforced with pure HAp nanorods. The possible strengthening of nanorods and the increase of SSA due to the reduction in the size of nanorods in the presence of yttrium may have contributed to the strengthening of Y-doped HAp/HMWPE composites. - Graphical Abstract: Highly ordered and oriented yttrium doped hydroxyapatite (HAp) nanorods were prepared by hydrothermal method. For undoped HAp the average length of the nanorod is 95 nm with mean diameter of 24 nm and for a Y doped nanorod the average length is {approx} 115 nm and the mean diameter is 15 nm. Mechanical analysis was carried out by polymer/nanoparticle composite method. Highlights: Black-Right-Pointing-Pointer Yttrium doped hydroxyapatite nanorods were prepared by hydrothermal method. Black-Right-Pointing-Pointer The nanorods have highly uniform size distribution. Black-Right-Pointing-Pointer Yttrium substitution and nanostructure formation was confirmed by careful analysis. Black-Right-Pointing-Pointer Mechanical strength was analyzed by polymer nanoparticle reinforcement method.« less

MO-FG-BRA-08: A Preliminary Study of Gold Nanoparticles Enhanced Diffuse Optical Tomography

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

Xu, K; Dogan, N; Yang, Y

2015-06-15

Purpose: To develop an imaging method by using gold nanoparticles (GNP) to enhance diffuse optical tomography (DOT) for better tumor detection. Methods: Experiments were performed on a tissue-simulating cylindrical optical phantom (30mm diameter, 60mm length). The GNP used are gold nanorods (10nm diameter, 44nm length) with peak light absorption at 840nm. 0.085ml GNP colloid of 96nM concentration was loaded into a 6mm diameter cylindrical hole in the phantom. An 856nm laser beam (14mW) was used as light source to irradiate the phantom at multiple locations through rotating and elevating the phantom. A CCD camera captured the light transmission through themore » phantom for each irradiation with total 40 projections (8 rotation angles in 45degree steps and 5 elevations with 3mm apart). Cone beam CT of the phantom was used to generate the three-dimensional mesh for DOT reconstruction and to identify the true location of the GNP volume. A forward simulation was performed with known phantom optical properties to establish a relationship between the absorption coefficient and concentration of the GNP by matching the simulated and measured transmission. DOT image reconstruction was performed to restore the GNP within the phantom. In addition, a region-constrained reconstruction was performed by confining the solutions within the GNP volume detected from CT. Results: The position of the GNP volume was reconstructed with <2mm error. The reconstructed average GNP concentration within an identical volume was 104nM, 8% difference from the truth. When the CT was used as “a priori”, the reconstructed average GNP concentration was 239nM, about 2.5 times of the true concentration. Conclusion: This study is the first to demonstrate GNP enhanced DOT with phantom imaging. The GNP can be differentiated from their surrounding background. However, the reconstruction methods needs to be improved for better spatial and quantification accuracy.« less

Antimicrobial Activity of New Materials Based on Lavender and Basil Essential Oils and Hydroxyapatite.

PubMed

Predoi, Daniela; Iconaru, Simona Liliana; Buton, Nicolas; Badea, Monica Luminita; Marutescu, Luminita

2018-04-30

This study presents, for the first-time, the results of a study on the hydrodynamic diameter of essential oils (EOs) of basil and lavender in water, and solutions of EOs of basil (B) and lavender (L) and hydroxyapatite (HAp). The possible influence of basil and lavender EOs on the size of hydroxyapatite nanoparticles was analyzed by Scanning Electron Microscopy (SEM). We also investigated the in vitro antimicrobial activity of plant EOs and plant EOs hydroxyapatite respectively, against Gram-positive bacteria (methicillin-resistant Staphylococcus aureus 1144 (MRSA 1144) and S. aureus 1426) and Gram-negative bacteria ( Escherichia coli ATCC 25922 and Escherichia coli ESBL 4493). From the autocorrelation function, obtained by Dynamic Light Scattering (DLS) measurements it was observed that basil yielded one peak at an average hydrodynamic diameter of 354.16 nm, while lavender yielded one peak at an average hydrodynamic diameter of 259.76 nm. In the case of HAp nanoparticles coated with basil (HApB) and lavender (HApL) essential oil, the aggregation was minimal. We found that the lavender EO exhibited a very good inhibitory growth activity (MIC values ranging from <0.1% for E. coli reference strain to 0.78% for S. aureus strains). The biological studies indicated that HapL material displayed an enhanced antimicrobial activity, indicating the potential use of HAp as vehicle for low concentrations of lavender EO with antibacterial properties. Flow cytometry analysis (FCM) allowed us to determine some of the potential mechanisms of the antimicrobial activities of EOs, suggesting that lavender EO was active against E. coli by interfering with membrane potential, the membrane depolarization effect being increased by incorporation of the EOs into the microporous structure of HAp. These findings could contribute to the development of new antimicrobial agents that are urgently needed for combating the antibiotic resistance phenomena.

Laboratory assessment of the mobility of water-dispersed engineered nanoparticles in a red soil (Ultisol)

NASA Astrophysics Data System (ADS)

Wang, Dengjun; Su, Chunming; Zhang, Wei; Hao, Xiuzhen; Cang, Long; Wang, Yujun; Zhou, Dongmei

2014-11-01

Soils are major sinks of engineered nanoparticles (ENPs) as results of land applications of sewage sludge, accidental spills, or deliberate applications of ENPs (e.g., nano-pesticides). In this study, the transport behaviors of four widely used ENPs (i.e., titanium dioxide [TiO2], buckminsterfullerene [C60], single-walled carbon nanotube [SWNT], and elemental silver [Ag0]) were investigated in water-saturated columns packed with either a quartz sand, a red soil (Ultisol), or sand/soil mixtures with soil mass fraction (λ) from 0% to 100% at slightly acidic solution pH (4.0-5.0). The mobility of tested ENPs decreased significantly with increasing λ, which was attributed to increased surface area and/or retention sites imparted by iron oxides, clay minerals, and organic matter in the red soil. Breakthrough curves of all ENPs exhibited blocking effects (decreasing deposition rate over time) and were well-described using an unfavorable and favorable, two-site kinetic attachment model accounting for random sequential adsorption on the favorable site. Modeled maximum retention capacity and first-order attachment rate coefficient on the favorable site both increased linearly with increasing λ, suggesting that transport parameters of ENPs in natural soils may be accurately extrapolated from transport parameters in the sand/soil mixtures. In addition, the mobility of three negatively charged ENPs (C60, SWNT, and Ag0 NPs) was reversely correlated with their average hydrodynamic diameters, highlighting that the average hydrodynamic diameter of negatively charged ENPs is the dominant physicochemical characteristics controlling their mobility in the Ultisol.

In situ measurements of plasma properties during gas-condensation of Cu nanoparticles

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

Koten, M. A., E-mail: mark.koten@gmail.com; Shield, J. E.; Voeller, S. A.

2016-03-21

Since the mean, standard deviation, and modality of nanoparticle size distributions can vary greatly between similar input conditions (e.g., power and gas flow rate), plasma diagnostics were carried out in situ using a double-sided, planar Langmuir probe to determine the effect the plasma has on the heating of clusters and their final size distributions. The formation of Cu nanoparticles was analyzed using cluster-plasma physics, which relates the processes of condensation and evaporation to internal plasma properties (e.g., electron temperature and density). Monitoring these plasma properties while depositing Cu nanoparticles with different size distributions revealed a negative correlation between average particlemore » size and electron temperature. Furthermore, the modality of the size distributions also correlated with the modality of the electron energy distributions. It was found that the maximum cluster temperature reached during plasma heating and the material's evaporation point regulates the growth process inside the plasma. In the case of Cu, size distributions with average sizes of 8.2, 17.3, and 24.9 nm in diameter were monitored with the Langmuir probe, and from the measurements made, the cluster temperatures for each deposition were calculated to be 1028, 1009, and 863 K. These values are then compared with the onset evaporation temperature of particles of this size, which was estimated to be 1059, 1068, and 1071 K. Thus, when the cluster temperature is too close to the evaporation temperature, less particle growth occurs, resulting in the formation of smaller particles.« less

Bioselective synthesis of gold nanoparticles from diluted mixed Au, Ir, and Rh ion solution by Anabaena cylindrica

NASA Astrophysics Data System (ADS)

Rochert, Anna S.; Rösken, Liz M.; Fischer, Christian B.; Schönleber, Andreas; Ecker, Dennis; van Smaalen, Sander; Geimer, Stefan; Wehner, Stefan

2017-11-01

Over the last years, an environmentally friendly and economically efficient way of nanoparticle production has been found in the biosynthesis of metal nanoparticles by bacteria and cyanobacteria. In this study, Anabaena cylindrica, a non-toxic cyanobacterium, is deployed in a diluted ionic aqueous mixture of equal concentrations of gold, iridium, and rhodium, of 0.1 mM each, for the selective biosynthesis of metal nanoparticles (NPs). To analyze the cyanobacterial metal uptake, X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and inductively coupled plasma mass spectrometry (ICP-MS) were applied. Only gold can be found in crystalline and nanoparticle form inside the cells of A. cylindrica, and it is the only metal for which ICP-MS analyses show a rapid decrease of the concentration in the culture medium. A slight decrease of rhodium and none of iridium was observed in the evaluated timeline of 51 h. The average diameter size of the emerging gold nanoparticles increased over the first few days, but is found to be below 10 nm even after more than 2 days. A new evaluation method was used to determine the spatially resolved distribution of the nanoparticles inside the cyanobacterial cells. This new method was also used to analyze TEM images from earlier studies of A. cylindrica and Anabaena sp., both incubated with an overall concentration of 0.8 mM Au3+ to compare the metal uptake. A. cylindrica was found to be highly selective towards the formation of gold nanoparticles in the presence of rhodium and iridium.

Silver/poly(vinyl alcohol) nanocomposite film prepared using water in oil microemulsion for antibacterial applications.

PubMed

Fatema, Ummul K; Rahman, M Muhibur; Islam, M Rakibul; Mollah, M Yousuf A; Susan, Md Abu Bin Hasan

2018-03-15

Water in oil microemulsion (w/o) is a simple preparative route for nanoparticles where water droplets (dispersed in continuous oil medium and stabilized by surfactants and cosurfactants) act as nanoreactors to carry out chemical reactions. If polymeric matrix is incorporated inside the core of the microemulsions, it should prevent the agglomeration of nanoparticles after separation from microemulsions. Thus polymer nanocomposite films prepared from w/o microemulsions are expected to give narrow and homogeneous size distribution of nanoparticles throughout the polymer host. Silver/poly(vinyl alcohol) (Ag/PVA) nanocomposite film was successfully prepared, for the first time, using Triton X-100 (TX-100)/1-butanol/cyclohexane/water microemulsion. Reduction of the metal salt was carried out in the core of w/o microemulsion droplets containing PVA polymeric matrix. After separation from the microemulsion, Ag/PVA nanocomposite film was then prepared by solution casting method. The antibacterial activity of the nanocomposites was tested against Gram-negative, Escherichia coli and Gram-positive, Staphylococcus aureus by agar diffusion method. Ag nanoparticles with an average diameter of 105 nm could be synthesized using PVA, whereas in the absence of PVA the nanoparticles agglomerated. The distribution of Ag nanoparticles on PVA surface of the nanocomposite film prepared using microemulsion was uniform, whereas the film prepared through in situ generation of Ag nanoparticles by chemical reduction process on PVA host showed non-uniform, coagulated, bunches of Ag nanoparticles. The film synthesized using microemulsion exhibited enhanced antibacterial efficacy compared to that prepared through in situ synthesis under the same test condition. Copyright © 2017 Elsevier Inc. All rights reserved.

Random Walk of Single Gold Nanoparticles in Zebrafish Embryos Leading to Stochastic Toxic Effects on Embryonic Developments

PubMed Central

Browning, Lauren M.; Lee, Kerry J.; Huang, Tao; Nallathamby, Prakash D.; Lowman, Jill E.; Xu, Xiao-Hong Nancy

2010-01-01

We have synthesized and characterized stable (non-aggregation, non-photobleaching and non-blinking), nearly monodisperse and highly-purified Au nanoparticles, and used them to probe transport of cleavage-stage zebrafish embryos and to study their effects on embryonic development in real time. We found that single Au nanoparticles (11.6 ± 0.9 nm in diameter) passively diffused into chorionic space of the embryos via their chorionic-pore-canals and continued their random-walk through chorionic space and into inner mass of embryos. Diffusion coefficients of single nanoparticles vary dramatically (2.8×10-11 to 1.3×10-8 cm2/s) as nanoparticles diffuse through various parts of embryos, suggesting highly diverse transport barriers and viscosity gradients of embryos. The amount of Au nanoparticles accumulated in embryos increase with its concentration. Interestingly, their effects on embryonic development are not proportionally related to the concentration. Majority of embryos (74% on average) incubated chronically with 0.025-1.2 nM Au nanoparticles for 120 h developed to normal zebrafish, with some (24%) being dead and few (2%) deformed. We developed a new approach to image and characterize individual Au nanoparticles embedded in tissues using histology sample preparation methods and LSRP spectra of single nanoparticles. We found that Au nanoparticles in various parts of normally developed and deformed zebrafish, suggesting that random-walk of nanoparticles in embryos during their development might have led to stochastic effects on embryonic development. These results show that Au nanoparticles are much more biocompatible (less toxic) to the embryos than Ag nanoparticles that we reported previously, suggesting that they are better suited as biocompatible probes for imaging embryos in vivo. The results provide powerful evidences that biocompatibility and toxicity of nanoparticles highly depend on their chemical properties, and the embryos can serve as effective in-vivo assays to screen their biocompatibility. PMID:20644873

TiO2 nanoparticles aggregation and disaggregation in presence of alginate and Suwannee River humic acids. pH and concentration effects on nanoparticle stability.

PubMed

Loosli, Frédéric; Le Coustumer, Philippe; Stoll, Serge

2013-10-15

The behavior of manufactured TiO2 nanoparticles is studied in a systematic way in presence of alginate and Suwannee River humic acids at variable concentrations. TiO2 nanoparticles aggregation, disaggregation and stabilization are investigated using dynamic light scattering and electrophoretic experiments allowing the measurement of z-average hydrodynamic diameters and zeta potential values. Stability of the TiO2 nanoparticles is discussed by considering three pH-dependent electrostatic scenarios. In the first scenario, when pH is below the TiO2 nanoparticle point of zero charge, nanoparticles exhibit a positively charged surface whereas alginate and Suwannee River humic acids are negatively charged. Fast adsorption at the TiO2 nanoparticles occurs, promotes surface charge neutralization and aggregation. By increasing further alginate and Suwannee River humic acids concentrations charge inversion and stabilization of TiO2 nanoparticles are obtained. In the second electrostatic scenario, at the surface charge neutralization pH, TiO2 nanoparticles are rapidly forming aggregates. Adsorption of alginate and Suwannee River humic acids on aggregates leads to their partial fragmentation. In the third electrostatic scenario, when nanoparticles, alginate and Suwannee River humic acids are negatively charged, only a small amount of Suwannee River humic acids is adsorbed on TiO2 nanoparticles surface. It is found that the fate and behavior of individual and aggregated TiO2 nanoparticles in presence of environmental compounds are mainly driven by the complex interplay between electrostatic attractive and repulsive interactions, steric and van der Waals interactions, as well as concentration ratio. Results also suggest that environmental aquatic concentration ranges of humic acids and biopolymers largely modify the stability of aggregated or dispersed TiO2 nanoparticles. Copyright © 2013 Elsevier Ltd. All rights reserved.

Growth of textured thin Au coatings on iron oxide nanoparticles with near infrared absorbance

PubMed Central

Ma, L L; Borwankar, A U; Willsey, B W; Yoon, K Y; Tam, J O; Sokolov, K V; Feldman, M D; Milner, T E; Johnston, K P

2013-01-01

A homologous series of Au-coated iron oxide nanoparticles, with hydrodynamic diameters smaller than 60 nm was synthesized with very low Auto-iron mass ratios as low as 0.15. The hydrodynamic diameter was determined by dynamic light scattering and the composition by atomic absorption spectroscopy and energy dispersive x-ray spectroscopy (EDS). Unusually low Au precursor supersaturation levels were utilized to nucleate and grow Au coatings on iron oxide relative to formation of pure Au nanoparticles. This approach produced unusually thin coatings, by lowering autocatalytic growth of Au on Au, as shown by transmission electron microscopy (TEM). Nearly all of the nanoparticles were attracted by a magnet indicating a minimal amount of pure Au particles The coatings were sufficiently thin to shift the surface plasmon resonance (SPR) to the near infrared (NIR), with large extinction coefficients., despite the small particle hydrodynamic diameters, observed from dynamic light scattering to be less than 60 nm. PMID:23238021

Spin Polarization and Quantum Spins in Au Nanoparticles

PubMed Central

Li, Chi-Yen; Karna, Sunil K.; Wang, Chin-Wei; Li, Wen-Hsien

2013-01-01

The present study focuses on investigating the magnetic properties and the critical particle size for developing sizable spontaneous magnetic moment of bare Au nanoparticles. Seven sets of bare Au nanoparticle assemblies, with diameters from 3.5 to 17.5 nm, were fabricated with the gas condensation method. Line profiles of the X-ray diffraction peaks were used to determine the mean particle diameters and size distributions of the nanoparticle assemblies. The magnetization curves M(Ha) reveal Langevin field profiles. Magnetic hysteresis was clearly revealed in the low field regime even at 300 K. Contributions to the magnetization from different size particles in the nanoparticle assemblies were considered when analyzing the M(Ha) curves. The results show that the maximum particle moment will appear in 2.4 nm Au particles. A similar result of the maximum saturation magnetization appearing in 2.3 nm Au particles is also concluded through analysis of the dependency of the saturation magnetization MP on particle size. The MP(d) curve departs significantly from the 1/d dependence, but can be described by a log-normal function. Magnetization can be barely detected for Au particles larger than 27 nm. Magnetic field induced Zeeman magnetization from the quantum confined Kubo gap opening appears in Au nanoparticles smaller than 9.5 nm in diameter. PMID:23989607

The effect of nanoparticle packing on capacitive electrode performance.

PubMed

Lee, Younghee; Noh, Seonmyeong; Kim, Min-Sik; Kong, Hye Jeong; Im, Kyungun; Kwon, Oh Seok; Kim, Sungmin; Yoon, Hyeonseok

2016-06-09

Nanoparticles pack together to form macro-scale electrodes in various types of devices, and thus, optimization of the nanoparticle packing is a prerequisite for the realization of a desirable device performance. In this work, we provide in-depth insight into the effect of nanoparticle packing on the performance of nanoparticle-based electrodes by combining experimental and computational findings. As a model system, polypyrrole nanospheres of three different diameters were used to construct pseudocapacitive electrodes, and the performance of the electrodes was examined at various nanosphere diameter ratios and mixed weight fractions. Two numerical algorithms are proposed to simulate the random packing of the nanospheres on the electrode. The binary nanospheres exhibited diverse, complicated packing behaviors compared with the monophasic packing of each nanosphere species. The packing of the two nanosphere species with lower diameter ratios at an optimized composition could lead to more dense packing of the nanospheres, which in turn could contribute to better device performance. The dense packing of the nanospheres would provide more efficient transport pathways for ions because of the reduced inter-nanosphere pore size and enlarged surface area for charge storage. Ultimately, it is anticipated that our approach can be widely used to define the concept of "the best nanoparticle packing" for desirable device performance.

An experimental study of the flow boiling of refrigerant-based nanofluids

NASA Astrophysics Data System (ADS)

Kolekar, Rahul Dadasaheb

The use of nanofluids for various heat transfer applications has been a topic of intense research over the last decade. A number of studies to evaluate the thermophysical properties and single-phase heat transfer behavior of nanofluids have been reported. The current study is focused on the use of nanofluids in flow boiling applications, with CO2 and R134a used as the base refrigerants. CuO nanoparticles 40nm in size, and TiO2 nanoparticles 200nm in size are used to create partially stable CO2-based nanofluids. Stable nanofluids are created in R134a by mixing it with dispersions of surface-treated nanoparticles in polyolester (POE) oil (RL22H and RL68H). The particles (Al 2O3, ZnO, CuO, and ATO) at particle mass fractions from 0.08% to 1.34%, with particle sizes of 20nm and 40nm are coated with polar and non-polar surface treatments. The thermal properties of R134a-based nanofluids are measured. Thermal conductivity shows limited improvements; the largest increase of 13% is observed with CuO nanoparticles. Significant increases in viscosity, as high as 2147%, are observed due to CuO nanoparticles. Only the ATO nanofluid exhibited a decrease in the measured viscosity. Heat transfer coefficients during flow boiling of nanofluids are measured over a range of mass flux from 100 to 1000 kg/m2s, with a heat flux from 5 to 25kW/m2, and vapor quality up to 1. The test section is a smooth copper tube, 6.23mm in diameter and 1.8m in length. Average decreases of 5% and 28% are observed in heat transfer coefficients during flow boiling of CuO/CO2 and TiO2/CO2 nanofluids, respectively. For the R134a-based nanofluids, average decreases in heat transfer during flow boiling at the highest particle mass fraction are 15% and 22% for Al2O3 and ZnO nanoparticles, respectively. CuO nanoparticles exhibit an average decrease of 7% for particle mass fraction of 0.08%. An average increase of 10% is observed with ATO nanoparticles at a 0.22% mass fraction. Heat transfer performance deteriorates with increase in viscosity and particle number density. The performance is also worse for partially stable nanofluids that modify the test section surface. Modifications to the thermophysical properties is the primary mechanism that affects heat transfer performance during flow boiling of nanofluids; increased thermal conductivity enhances while increased viscosity and surface tension reduce heat transfer in nucleate boiling-dominated flows. A secondary mechanism of nanoparticles filling up the micro-cavities on test surface is also responsible for decreased heat transfer and is a strong function of particle number density.

The importance of “going nano” for high power battery materials

NASA Astrophysics Data System (ADS)

Bresser, Dominic; Paillard, Elie; Copley, Mark; Bishop, Peter; Winter, Martin; Passerini, Stefano

2012-12-01

The electrochemical performance of spinel Li4Ti5O12 (LTO) nanoparticles synthesized by flame spray pyrolysis with an average diameter of approximately 20-30 nm is reported in this manuscript and compared with that of micro-sized LTO particles (1-2 μm) formed by a thermal post-treatment of the nanoparticles. The significantly advanced high rate capability of nano-sized LTO is evidenced by the results from the galvanostatic tests with applied current densities of up to 17.5 A g-1, corresponding to a full (dis-)charge of the cell within less than 40 s. For nano-sized LTO, specific capacities of 115 and 70 mAh g-1 were obtained for applied rates of 10 C and 100 C, respectively, thus confirming the essential influence of particle size of lithium titanate on its high rate capability and practical power density. Moreover, a capacity retention of around 94.8% was observed after 1000 cycles at 10 C, presenting LTO nanoparticles synthesized by FSP as highly promising anode material for high power lithium-ion battery applications.

Fresnel Lorentz Microscopy Imaging of Domains in Fe3O4 Nanoparticle Arrays

NASA Astrophysics Data System (ADS)

Majetich, S. A.; Evarts, E. R.; Hogg, C.; Yamamoto, K.; Hirayama, T.

2009-03-01

Fresnel Lorentz microscopy was used to study the magnetic domain structures of self-assembled nanoparticle arrays as a function of temperature, from 24 to 605 C. 11 nm diameter Fe3O4 nanoparticles with an edge-to-edge spacing of 2.5 nm form magnetic domains through magnetostatic interactions alone. At room temperature stripe domains were evident in monolayer arrays. The average domain size in monolayer regions is larger than that in bilayers. Mean field theories predict a reduced stabilization energy for bilayers, relative to that for monolayers. The domain wall positions were fairly stable up to 500 C, though the contrast in the walls diminished, indicating reduced magnetic order. Above 500 C there were large temperature-dependent changes. The walls surrounding the smaller domains disappeared at lower temperatures than those of the larger domains. Some magnetic contrast was visible up to 575 C, close to the Curie temperature of Fe3O4 (585 C). Transmission electron microscopy after cooling showed that the particle shape and position in the ordered arrays had been preserved during the high temperature imaging experiments.

Modified WO3 nanorod with Pt nanoparticle as retrievable materials in catalytic and photocatalytic aerobic oxidation of alcohols

NASA Astrophysics Data System (ADS)

Hosseini, Farnaz; Safaei, Elham; Mohebbi, Sajjad

2017-07-01

This study has focused on catalytic and photocatalytic oxidation of aromatic alcohols using WO3 nanorod and a series of Pt/WO3 nanocomposite Pt nanoparticles was loaded on WO3 nanorod with several mass ratios 0.1, 0.2, and 0.3 via a photoreduction process (PRP) and characterized by TEM, FE-SEM imaging, EDAX, XRD, DRS, ICP, and XPS. WO3 nanorods were obtained monodispersed with average 40-nm diameter and square cross section without significant size change by the loading of platinum nanoparticles on it. Progress of oxidation reaction was monitored by GC and the yield of aerobic photocatalytic oxidation of alcohols reached up to 98% for Pt/WO3 and 69% for WO3 while, no oxidation was detected in the absence of light. The highest photocatalytic performance was obtained for mass ratio 0.2 with the selectivity >99%. So, this nanocomposite has potentials to be used as high-performance heterogeneous catalyst and photocatalyst under visible light irradiation with advantages of high activity, high selectivity, and reusability.

Magnetic nanoparticles for a new drug delivery system to control quercetin releasing for cancer chemotherapy

NASA Astrophysics Data System (ADS)

Barreto, A. C. H.; Santiago, V. R.; Mazzetto, S. E.; Denardin, J. C.; Lavín, R.; Mele, Giuseppe; Ribeiro, M. E. N. P.; Vieira, Icaro G. P.; Gonçalves, Tamara; Ricardo, N. M. P. S.; Fechine, P. B. A.

2011-12-01

Quercetin belongs to the chemical class of flavonoids and can be found in many common foods, such as apples, nuts, berries, etc. It has been demonstrated that quercetin has a wide array of biological effects that are considered beneficial to health treatment, mainly as anticancer. However, therapeutic applications of quercetin have been restricted to oral administration due to its sparing solubility in water and instability in physiological medium. A drug delivery methodology was proposed in this work to study a new quercetin release system in the form of magnetite-quercetin-copolymer (MQC). These materials were characterized through XRD, TEM, IR, and Thermal analysis. In addition, the magnetization curves and quercetin releasing experiments were performed. It was observed a nanoparticle average diameter of 11.5 and 32.5 nm at Fe3O4 and MQC, respectively. The presence of magnetic nanoparticles in this system offers the promise of targeting specific organs within the body. These results indicate the great potential for future applications of the MQC to be used as a new quercetin release system.

Synthesis, self-assembly, and properties of Mn doped ZnO nanoparticles.

PubMed

Barick, K C; Bahadur, D

2007-06-01

We report here a novel process to prepare Mn doped ZnO nanoparticles by a soft chemical route at low temperature. The synthesis process is based on the hydrolysis of zinc acetate dihydrate and manganese acetate tetrahydrate heated under reflux to 160-175 degrees C using diethylene glycol as a solvent. X-ray diffraction analysis reveals that the Mn doped ZnO crystallizes in a wurtzite structure with crystal size of 15-25 nm. These nano size crystallites of Mn doped ZnO self-organize into polydisperse spheres in size ranging from 100-400 nm. Transmission Electron Microscopy image also shows that each sphere is made up of numerous nanocrystals of average diameter 15-25 nm. By means of X-ray photoelectron spectroscopy and electron spin resonance spectroscopy, we determined the valence state of Mn ions as 2+. These nanoparticles were found to be ferromagnetic at room temperature. Monodisperse porous spheres (approximately 250 nm) were obtained by size selective separation technique and then self-assembled in a closed pack periodic array through sedimentation with slow solvent evaporation, which gives strong opalescence in visible region.

Development of a new sensitive immunostrip assay based on mesoporous silica and colloidal Au nanoparticles.

PubMed

Omidfar, Kobra; Khorsand, Behnosh; Larijani, Bagher

2012-02-01

A new competitive immunostrip assay was developed to detect human serum albumin (HSA) in urine sample with use of conjugated monoclonal antibody gold nanoparticles (mAb-AuNPs) and mobile crystalline material (MCM)-41-HSA bioconjugate. To prepare the immunostrip, the colloidal AuNPs with an average particle diameter of 20 nm, was synthesized, labeled with antibody and applied on the conjugate pad as the detection reagent. Then, HSA was attached to the MCM-41 mesoporous nanoparticles and immobilized to a nitrocellulose membrane as the test line. In the optimized investigational conditions, the immunostrip could detect HSA in a high linear range (from 1 to 200 μg/ml) and low detection limit (ng/ml). The reliability of the testing procedure was examined by performing the immunostrip test with 30 urine samples and comparing the results with those obtained via immunoturbidimetry. The immunostrip was adequately sensitive and accurate for a rapid screening of HSA in the urine. This new strategy for competitive immunostrip design can be used and developed for other antigen based immunostrip assay.

Flux pinning and inhomogeneity in magnetic nanoparticle doped MgB2/Fe wires

NASA Astrophysics Data System (ADS)

Novosel, Nikolina; Pajić, Damir; Mustapić, Mislav; Babić, Emil; Shcherbakov, Andrey; Horvat, Joseph; Skoko, Željko; Zadro, Krešo

2010-06-01

The effects of magnetic nanoparticle doping on superconductivity of MgB2/Fe wires have been investigated. Fe2B and SiO2-coated Fe2B particles with average diameters 80 and 150 nm, respectively, were used as dopands. MgB2 wires with different nanoparticle contents (0, 3, 7.5, 12 wt.%) were sintered at temperature 750°C. The magnetoresistivity and critical current density Jc of wires were measured in the temperature range 2-40 K in magnetic field B <= 16 T. Both transport and magnetic Jc were determined. Superconducting transition temperature Tc of doped wires decreases quite rapidly with doping level (~ 0.5 K per wt.%). This results in the reduction of the irreversibility fields Birr(T) and critical current densities Jc(B,T) in doped samples (both at low (5 K) and high temperatures (20 K)). Common scaling of Jc(B,T) curves for doped and undoped wires indicates that the main mechanism of flux pinning is the same in both types of samples. Rather curved Kramer's plots for Jc of doped wires imply considerable inhomogeneity.

In Vitro Sustained Release Study of Gallic Acid Coated with Magnetite-PEG and Magnetite-PVA for Drug Delivery System

PubMed Central

Kura, Aminu Umar; Hussein-Al-Ali, Samer Hasan; Bin Hussein, Mohd Zobir; Fakurazi, Sharida; Shaari, Abdul Halim; Ahmad, Zalinah

2014-01-01

The efficacy of two nanocarriers polyethylene glycol and polyvinyl alcohol magnetic nanoparticles coated with gallic acid (GA) was accomplished via X-ray diffraction, infrared spectroscopy, magnetic measurements, thermal analysis, and TEM. X-ray diffraction and TEM results showed that Fe3O4 nanoparticles were pure iron oxide having spherical shape with the average diameter of 9 nm, compared with 31 nm and 35 nm after coating with polyethylene glycol-GA (FPEGG) and polyvinyl alcohol-GA (FPVAG), respectively. Thermogravimetric analyses proved that after coating the thermal stability was markedly enhanced. Magnetic measurements and Fourier transform infrared (FTIR) revealed that superparamagnetic iron oxide nanoparticles could be successfully coated with two polymers (PEG and PVA) and gallic acid as an active drug. Release behavior of gallic acid from two nanocomposites showed that FPEGG and FPVAG nanocomposites were found to be sustained and governed by pseudo-second-order kinetics. Anticancer activity of the two nanocomposites shows that the FPEGG demonstrated higher anticancer effect on the breast cancer cell lines in almost all concentrations tested compared to FPVAG. PMID:24737969

Functional biocompatible magnetite-cellulose nanocomposite fibrous networks: Characterization by fourier transformed infrared spectroscopy, X-ray powder diffraction and field emission scanning electron microscopy analysis.

PubMed

Habibi, Neda

2015-02-05

The preparation and characterization of functional biocompatible magnetite-cellulose nano-composite fibrous material is described. Magnetite-cellulose nano-composite was prepared by a combination of the solution-based formation of magnetic nano-particles and subsequent coating with amino celluloses. Characterization was accomplished using X-ray powder diffraction (XRD), fourier transformed infrared (FTIR) and field emission scanning electron microscopy (FESEM) analysis. The peaks of Fe3O4 in the XRD pattern of nanocomposite confirm existence of the nanoparticles in the amino cellulose matrix. Magnetite-cellulose particles exhibit an average diameter of roughly 33nm as demonstrated by field emission scanning electron microscopy. Magnetite nanoparticles were irregular spheres dispersed in the cellulose matrix. The vibration corresponding to the NCH3 functional group about 2850cm(-1) is assigned in the FTIR spectra. Functionalized magnetite-cellulose nano-composite polymers have a potential range of application as targeted drug delivery system in biomedical field. Copyright © 2014 Elsevier B.V. All rights reserved.

Combined Effect of Ultrasound Stimulations and Autoclaving on the Enhancement of Antibacterial Activity of ZnO and SiO₂/ZnO Nanoparticles.

PubMed

Rokbani, Hajer; Daigle, France; Ajji, Abdellah

2018-02-25

This study investigates the antibacterial activity (ABA) of suspensions of pure ZnO nanoparticles (ZnO-NPs) and mesoporous silica doped with ZnO (ZnO-UVM7), as well as electrospun nanofibers containing those nanoparticles. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of these two materials were also determined under the same conditions. The results showed a concentration-dependent effect of antibacterial nanoparticles on the viability of Escherichia coli ( E. coli ). Moreover, the combination of the stimulations and sterilization considerably enhanced the antimicrobial activity (AMA) of the ZnO suspensions. Poly (lactic acid) (PLA) solutions in 2,2,2-trifluoroethanol (TFE) were mixed with different contents of nanoparticles and spun into nonwoven mats by the electrospinning process. The morphology of the mats was analyzed by scanning electron microscopy (SEM). The amount of nanoparticles contained in the mats was determined by thermogravimetric analysis (TGA). The obtained PLA-based mats showed a fibrous morphology, with an average diameter ranging from 350 to 450 nm, a porosity above 85%, but with the nanoparticles agglomeration on their surface. TGA analysis showed that the loss of ZnO-NPs increased with the increase of ZnO-NPs content in the PLA solutions and reached 79% for 1 wt % of ZnO-NPs, which was mainly due to the aggregation of nanoparticles in solution. The ABA of the obtained PLA mats was evaluated by the dynamic method according to the ASTM standard E2149. The results showed that, above an optimal concentration, the nanoparticle agglomeration reduced the antimicrobial efficiency of PLA mats. These mats have potential features for use as antimicrobial food packaging material.

Estradiol-loaded PLGA nanoparticles for improving low bone mineral density of cancellous bone caused by osteoporosis: Application of enhanced charged nanoparticles with iontophoresis.

PubMed

Takeuchi, Issei; Kobayashi, Shiori; Hida, Yukari; Makino, Kimiko

2017-07-01

Postmenopausal osteoporosis among older women, which occurs by an ovarian hormone deficiency, is one of the major public health problems. 17 β-estradiol (E2) is used to prevent and treat this disease as a drug of hormone replacement therapy. In oral administration, E2 is significantly affected by first-pass hepatic metabolism, and high dose administration must be needed to obtain drug efficacy. Therefore, alternative administration route is needed, and we have focused on the transdermal drug delivery system. In this study, we have prepared E2-loaded poly(DL-lactide-co-glycolide) (PLGA) nanoparticles for osteoporosis by using a combination of an antisolvent diffusion method with preferential solvation. The average particle diameter of the nanoparticles was 110.0±41.0nm and the surface charge number density was 82 times higher than that of conventional E2-loaded PLGA nanoparticles. Therapeutic evaluation of E2-loaded PLGA nanoparticles was carried out using ovariectomized female rats. Therapeutic efficacy was evaluated to measure bone mineral density of cancellous bone using an X-ray CT system. When the E2-loaded PLGA nanoparticles were administrated once a week, bone mineral density was significantly higher than that of the non-treated group at 60days after the start of treatment. Also, in the group administered this nanoparticle twice a week, the bone mineral density increased significantly at 45days after the start of treatment. From these results, it was revealed that E2-loaded PLGA nanoparticles with iontophoresis were useful to recover bone mineral density of cancellous bone, and it was also suggested that they extend the dosing interval of E2. Copyright © 2017 Elsevier B.V. All rights reserved.

The antihypertensive effect of orally administered nifedipine-loaded nanoparticles in spontaneously hypertensive rats.

PubMed

Kim, Y I; Fluckiger, L; Hoffman, M; Lartaud-Idjouadiene, I; Atkinson, J; Maincent, P

1997-02-01

1. The therapeutic use of nifedipine is limited by the rapidity of the onset of its action and its short biological half-life. In order to produce a form devoid of these disadvantages we made nanoparticles of nifedipine from three different polymers, poly-epsilon-caprolactone (PCL), polylactic and glycolic acid (1:1) copolymers (PLAGA), and Eudragit RL/RS (Eudragit). Nifedipine in polyethylene glycol 400 (PEG) solution was used as a control. 2. The average diameters of the nanoparticles ranged from 0.12 to 0.21 micron; the encapsulation ratio was 82% to 88%. 3. In spontaneously hypertensive rats (SHR), the initial rapid fall in systolic arterial blood pressure following oral administration of nifedipine in PEG solution (from 193 +/- 3 to 102 +/- 2 mmHg) was not seen following administration of the same dose in Eudragit nanoparticles (from 189 +/- 2 to 156 +/- 2 mmHg); with PCL and PLAGA nanoparticles the initial fall in blood pressure was significantly reduced (nadirs PCL 124 +/- 2 and PLAGA 113 +/- 2 mmHg). Ten hours following administration, blood pressure in rats administered the nifedipine/PEG preparation had returned to normal (183 +/- 3 mmHg) whereas that of animals given nifedipine in nanoparticles (PCL 170 +/- 3, PLAGA 168 +/- 2, Eudragit 160 +/- 3 mmHg) was still significantly reduced. 4. All of the nanoparticle dosage forms decreased Cmax and increased Tmax and the mean residence time (MRT) values. Relative bioavailability was significantly increased with Eudragit nanoparticles compared to the nifedipine/PEG solution. 5. There was an inverse linear correlation between the fall in blood pressure and plasma nifedipine concentration with all preparations. 6. The nanoparticle nifedipine preparations represent sustained release forms with increased bioavailability, a less pronounced initial antihypertensive effect and a long-lasting action.

Combined Effect of Ultrasound Stimulations and Autoclaving on the Enhancement of Antibacterial Activity of ZnO and SiO2/ZnO Nanoparticles

PubMed Central

Rokbani, Hajer; Ajji, Abdellah

2018-01-01

This study investigates the antibacterial activity (ABA) of suspensions of pure ZnO nanoparticles (ZnO-NPs) and mesoporous silica doped with ZnO (ZnO-UVM7), as well as electrospun nanofibers containing those nanoparticles. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of these two materials were also determined under the same conditions. The results showed a concentration-dependent effect of antibacterial nanoparticles on the viability of Escherichia coli (E. coli). Moreover, the combination of the stimulations and sterilization considerably enhanced the antimicrobial activity (AMA) of the ZnO suspensions. Poly (lactic acid) (PLA) solutions in 2,2,2-trifluoroethanol (TFE) were mixed with different contents of nanoparticles and spun into nonwoven mats by the electrospinning process. The morphology of the mats was analyzed by scanning electron microscopy (SEM). The amount of nanoparticles contained in the mats was determined by thermogravimetric analysis (TGA). The obtained PLA-based mats showed a fibrous morphology, with an average diameter ranging from 350 to 450 nm, a porosity above 85%, but with the nanoparticles agglomeration on their surface. TGA analysis showed that the loss of ZnO-NPs increased with the increase of ZnO-NPs content in the PLA solutions and reached 79% for 1 wt % of ZnO-NPs, which was mainly due to the aggregation of nanoparticles in solution. The ABA of the obtained PLA mats was evaluated by the dynamic method according to the ASTM standard E2149. The results showed that, above an optimal concentration, the nanoparticle agglomeration reduced the antimicrobial efficiency of PLA mats. These mats have potential features for use as antimicrobial food packaging material. PMID:29495334

Iron oxide nanoparticles stabilized with dendritic polyglycerols as selective MRI contrast agents

NASA Astrophysics Data System (ADS)

Nordmeyer, Daniel; Stumpf, Patrick; Gröger, Dominic; Hofmann, Andreas; Enders, Sven; Riese, Sebastian B.; Dernedde, Jens; Taupitz, Matthias; Rauch, Ursula; Haag, Rainer; Rühl, Eckart; Graf, Christina

2014-07-01

Monodisperse small iron oxide nanoparticles functionalized with dendritic polyglycerol (dPG) or dendritic polyglycerol sulfate (dPGS) are prepared. They are highly stable in aqueous solutions as well as physiological media. In particular, oleic acid capped iron oxide particles (core diameter = 11 +/- 1 nm) were modified by a ligand exchange process in a one pot synthesis with dPG and dPGS bearing phosphonate as anchor groups. Dynamic light scattering measurements performed in water and different biological media demonstrate that the hydrodynamic diameter of the particles is only slightly increased by the ligand exchange process resulting in a final diameter of less than 30 nm and that the particles are stable in these media. It is also revealed by magnetic resonance studies that their magnetic relaxivity is reduced by the surface modification but it is still sufficient for high contrast magnetic resonance imaging (MRI). Additionally, incubation of dPGS functionalized iron oxide nanoparticles with human umbilical vein endothelial cells showed a 50% survival at 85 nM (concentration of nanoparticles). Surface plasmon resonance (SPR) studies demonstrate that the dPGS functionalized iron oxide nanoparticles inhibit L-selectin ligand binding whereas the particles containing only dPG do not show this effect. Experiments in a flow chamber with human myelogenous leukemia cells confirmed L-selectin inhibition of the dPGS functionalized iron oxide nanoparticles and with that the L-selectin mediated leukocyte adhesion. These results indicate that dPGS functionalized iron oxide nanoparticles are a promising contrast agent for inflamed tissue probed by MRI.Monodisperse small iron oxide nanoparticles functionalized with dendritic polyglycerol (dPG) or dendritic polyglycerol sulfate (dPGS) are prepared. They are highly stable in aqueous solutions as well as physiological media. In particular, oleic acid capped iron oxide particles (core diameter = 11 +/- 1 nm) were modified by a ligand exchange process in a one pot synthesis with dPG and dPGS bearing phosphonate as anchor groups. Dynamic light scattering measurements performed in water and different biological media demonstrate that the hydrodynamic diameter of the particles is only slightly increased by the ligand exchange process resulting in a final diameter of less than 30 nm and that the particles are stable in these media. It is also revealed by magnetic resonance studies that their magnetic relaxivity is reduced by the surface modification but it is still sufficient for high contrast magnetic resonance imaging (MRI). Additionally, incubation of dPGS functionalized iron oxide nanoparticles with human umbilical vein endothelial cells showed a 50% survival at 85 nM (concentration of nanoparticles). Surface plasmon resonance (SPR) studies demonstrate that the dPGS functionalized iron oxide nanoparticles inhibit L-selectin ligand binding whereas the particles containing only dPG do not show this effect. Experiments in a flow chamber with human myelogenous leukemia cells confirmed L-selectin inhibition of the dPGS functionalized iron oxide nanoparticles and with that the L-selectin mediated leukocyte adhesion. These results indicate that dPGS functionalized iron oxide nanoparticles are a promising contrast agent for inflamed tissue probed by MRI. Electronic supplementary information (ESI) available: A detailed description of the synthesis of the ligands as well as the preparation and functionalization of the iron oxide nanoparticles including their physico-chemical characterization are presented. Further, details of the cell experiments and the SPR experiments are given. Two representative movies are provided showing leukocyte rolling on the ligand coated surface of the flow chamber. See DOI: 10.1039/c3nr04793h

Morphology and stability in a half-metallic ferromagnetic CrO 2 compound of nanoparticles synthesized via a polymer precursor

NASA Astrophysics Data System (ADS)

Biswas, S.; Ram, S.

2004-11-01

Nanoparticles of stable CrO2 of a half-metallic ferromagnet are synthesized with a novel chemical method involving a Cr4+-polymer composite precursor. A single phase CrO2 of D4h 14 : P42 / mnm tetragonal crystal structure (lattice parameters a = 0.4250 and c = 0.3190 nm) lies after firing the precursor at 350 °C for 1 h in air. Microstructure reveals single domain CrO2 particles of thin platelets (aspect ratio ∼1) of average 50 nm diameter and 35 nm thickness. In air, unless heating at temperatures above 500 °C, no due CrO2 → Cr2O3 phase transformation encounters. The results are presented in terms of X-ray diffraction and thermal or thermogravimetric analysis of precursor and derived CrO2 powder.

Size-dependent antimicrobial properties of sugar-encapsulated gold nanoparticles synthesized by a green method

PubMed Central

2012-01-01

The antimicrobial properties of dextrose-encapsulated gold nanoparticles (dGNPs) with average diameters of 25, 60, and 120 nm (± 5) and synthesized by green chemistry principles were investigated against both Gram-negative and Gram-positive bacteria. Studies were performed involving the effect of dGNPs on the growth, morphology, and ultrastructural properties of bacteria. dGNPs were found to have significant dose-dependent antibacterial activity which was also proportional to their size. Experiments revealed the dGNPs to be bacteriostatic as well as bactericidal. The dGNPs exhibited their bactericidal action by disrupting the bacterial cell membrane which leads to the leakage of cytoplasmic content. The overall outcome of this study suggests that green-synthesized dGNPs hold promise as a potent antibacterial agent against a wide range of disease-causing bacteria by preventing and controlling possible infections or diseases. PMID:23146145

Decorrelation correction for nanoparticle tracking analysis of dilute polydisperse suspensions in bulk flow

NASA Astrophysics Data System (ADS)

Hartman, John; Kirby, Brian

2017-03-01

Nanoparticle tracking analysis, a multiprobe single particle tracking technique, is a widely used method to quickly determine the concentration and size distribution of colloidal particle suspensions. Many popular tools remove non-Brownian components of particle motion by subtracting the ensemble-average displacement at each time step, which is termed dedrifting. Though critical for accurate size measurements, dedrifting is shown here to introduce significant biasing error and can fundamentally limit the dynamic range of particle size that can be measured for dilute heterogeneous suspensions such as biological extracellular vesicles. We report a more accurate estimate of particle mean-square displacement, which we call decorrelation analysis, that accounts for correlations between individual and ensemble particle motion, which are spuriously introduced by dedrifting. Particle tracking simulation and experimental results show that this approach more accurately determines particle diameters for low-concentration polydisperse suspensions when compared with standard dedrifting techniques.

A high brightness probe of polymer nanoparticles for biological imaging

NASA Astrophysics Data System (ADS)

Zhou, Sirong; Zhu, Jiarong; Li, Yaping; Feng, Liheng

2018-03-01

Conjugated polymer nanoparticles (CPNs) with high brightness in long wavelength region were prepared by the nano-precipitation method. Based on fluorescence resonance energy transfer (FRET) mechanism, the high brightness property of the CPNs was realized by four different emission polymers. Dynamic light scattering (DLS) and scanning electron microscopy (SEM) displayed that the CPNs possessed a spherical structure and an average diameter of 75 nm. Analysis assays showed that the CPNs had excellent biocompatibility, good photostability and low cytotoxicity. The CPNs were bio-modified with a cell penetrating peptide (Tat, a targeted element) through covalent link. Based on the entire wave fluorescence emission, the functionalized CPNs1-4 can meet multichannel and high throughput assays in cell and organ imaging. The contribution of the work lies in not only providing a new way to obtain a high brightness imaging probe in long wavelength region, but also using targeted cell and organ imaging.

One-step formation of TiO2 hollow spheres via a facile microwave-assisted process for photocatalytic activity

NASA Astrophysics Data System (ADS)

Mohamad Alosfur, Firas K.; Ridha, Noor J.; Hafizuddin Haji Jumali, Mohammad; Radiman, S.

2018-04-01

Mesoporous TiO2 hollow spherical nanostructures with high surface areas were successfully prepared using a microwave method. The prepared hollow spheres had a size range between 200 and 500 nm. The spheres consisted of numerous smaller TiO2 nanoparticles with an average diameter of 8 nm. The particles had an essentially mesoporous structure, with a pore size in the range of 2-50 nm. The results confirmed that the synthesised of anatase TiO2 nanoparticles with specific surface area approximately 172.3 m2 g-1. The effect of ultraviolet and visible light irradiation and catalyst dosage on the TiO2 photocatalytic activity was studied by measuring the degradation rate of methylene blue. The maximum dye degradation performances with low catalyst loading (30 mg) were 99% and 63.4% using the same duration of ultraviolet and visible light irradiation, respectively (120 min).

A facile growth mechanism, structural, optical, dielectric and electrical properties of ZnSe nanosphere via hydrothermal process

NASA Astrophysics Data System (ADS)

Javed, Qurat-Ul-Ain; Baqi, Sabah; Abbas, Hussain; Bibi, Maryam

2017-02-01

Hydrothermal method was chosen as a convenient method to fabricate zinc selenide (ZnSe) nanoparticle materials. The prepared nanospheres were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM), where its different properties were observed using UV-visible spectroscopy and LCR meter. It was found that the pure ZnSe nanoparticles have a Zinc blende structure with crystallite size 10.91 nm and in a spherical form with average diameter of 35 nm (before sonication) and 18 nm (after sonication) with wide band gap of 4.28 eV. It was observed that there is inverse relation of frequency with dielectric constant and dielectric loss while AC conductivity grows up by increasing frequency. Such nanostructures were determined to be effectively used in optoelectronic devices as UV detector and in those devices where high-dielectric constant materials are required.

Effects of ion and nanosecond-pulsed laser co-irradiation on the surface nanostructure of Au thin films on SiO{sub 2} glass substrates

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

Yu, Ruixuan; Meng, Xuan; Takayanagi, Shinya

2014-04-14

Ion irradiation and short-pulsed laser irradiation can be used to form nanostructures on the surfaces of substrates. This work investigates the synergistic effects of ion and nanosecond-pulsed laser co-irradiation on surface nanostructuring of Au thin films deposited under vacuum on SiO{sub 2} glass substrates. Gold nanoparticles are randomly formed on the surface of the substrate after nanosecond-pulsed laser irradiation under vacuum at a wavelength of 532 nm with a repetition rate of 10 Hz and laser energy density of 0.124 kJ/m{sup 2}. Gold nanoparticles are also randomly formed on the substrate after 100-keV Ar{sup +} ion irradiation at doses of upmore » to 3.8 × 10{sup 15} ions/cm{sup 2}, and nearly all of these nanoparticles are fully embedded in the substrate. With increasing ion irradiation dose (number of incident laser pulses), the mean diameter of the Au nanoparticles decreases (increases). However, Au nanoparticles are only formed in a periodic surface arrangement after co-irradiation with 6000 laser pulses and 3.8 × 10{sup 15} ions/cm{sup 2}. The periodic distance is ∼540 nm, which is close to the wavelength of the nanosecond-pulsed laser, and the mean diameter of the Au nanoparticles remains at ∼20 nm with a relatively narrow distribution. The photoabsorption peaks of the ion- or nanosecond-pulsed laser-irradiated samples clearly correspond to the mean diameter of Au nanoparticles. Conversely, the photoabsorption peaks for the co-irradiated samples do not depend on the mean nanoparticle diameter. This lack of dependence is likely caused by the periodic nanostructure formed on the surface by the synergistic effects of co-irradiation.« less

Clinically Approved Nanoparticle Imaging Agents

PubMed Central

Thakor, Avnesh S.; Jokerst, Jesse V.; Ghanouni, Pejman; Campbell, Jos L.; Mittra, Erik

2016-01-01

Nanoparticles are a new class of imaging agent used for both anatomic and molecular imaging. Nanoparticle-based imaging exploits the signal intensity, stability, and biodistribution behavior of submicron-diameter molecular imaging agents. This review focuses on nanoparticles used in human medical imaging, with an emphasis on radionuclide imaging and MRI. Newer nanoparticle platforms are also discussed in relation to theranostic and multimodal uses. PMID:27738007

Pronounced effects of the nominal concentrations of WO3 and Ag: WO3 nano-plates (obtained by a co-precipitation method) on their structural, morphological and optical properties

NASA Astrophysics Data System (ADS)

Rajendran, V.; Deepa, B.

2018-03-01

Tungsten oxide and different concentration of silver (Ag)-doped tungsten oxide nano material were synthesized by co-precipitation technique. The functional vibrations, structure, and morphology of as-prepared nano material were studied by Fourier transmission infrared spectroscopy, X-ray diffraction, scanning electron microscopy (SEM) and High-resolution transmission electron microscopy (HR-TEM) techniques. The SEM and HR-TEM analysis revealed the formation of nano-plate/nano rods with an average diameter of 40-80 nm diameter and 1-1.5 mm length. Fluorescence (PL) and UV-visible absorption techniques have been used to study the optical properties of the prepared nanoparticles. The observed red shift in the visible absorption spectra confirmed the promoted electron-phonon interaction in WO3 and Ag: WO3 nanoparticles compared to bulk structures. The photoluminescence of nanocrystalline Ag2+ doped WO3 exhibited a strong violet-blue, blue-green emission. Concentration dependence of the emission intensity of Ag2+ in WO3 was studied, and the significant concentration was found to be 0.5% of Ag: WO3. The effluent dye degradation executed for the 0.5% of Ag: WO3 sample under the visible light which reveals the highest degradation efficiency in appropriate time.

Observations of internal flow inside an evaporating nanofluid sessile droplet in the presence of an entrapped air bubble

PubMed Central

Shin, Dong Hwan; Allen, Jeffrey S.; Lee, Seong Hyuk; Choi, Chang Kyoung

2016-01-01

Using a unique, near-field microscopy technique, fringe patterns and nanoparticle motions are visualized immediately following a nanofluid droplet deposition on a glass substrate in which an air bubble is entrapped. The nanofluid consists of DI-water, 0.10% Aluminum Oxide nanoparticles with an average diameter of 50 nm, and 0.0005% yellow-green polystyrene fluorescent particles of 1 μm diameter. High-speed, fluorescent-mode confocal imaging enables investigation of depth-wise sectioned particle movements in the nanofluid droplet inside which a bubble is entrapped. The static contact angle is increased when a bubble is applied. In the presence of the bubble in the droplet, the observed flow toward the center of the droplet is opposite to the flow observed in a droplet without the bubble. When the bubble is present, the evaporation process is retarded. Also, random motion is observed in the contact line region instead of the typical evaporation-driven flow toward the droplet edge. Once the bubble bursts, however, the total evaporation time decreases due to the change in the contact line characteristics. Moreover, the area of fringe patterns beneath the bubble increases with time. Discussed herein is a unique internal flow that has not been observed in nanofluid droplet evaporation. PMID:27615999

Observations of internal flow inside an evaporating nanofluid sessile droplet in the presence of an entrapped air bubble.

PubMed

Shin, Dong Hwan; Allen, Jeffrey S; Lee, Seong Hyuk; Choi, Chang Kyoung

2016-09-12

Using a unique, near-field microscopy technique, fringe patterns and nanoparticle motions are visualized immediately following a nanofluid droplet deposition on a glass substrate in which an air bubble is entrapped. The nanofluid consists of DI-water, 0.10% Aluminum Oxide nanoparticles with an average diameter of 50 nm, and 0.0005% yellow-green polystyrene fluorescent particles of 1 μm diameter. High-speed, fluorescent-mode confocal imaging enables investigation of depth-wise sectioned particle movements in the nanofluid droplet inside which a bubble is entrapped. The static contact angle is increased when a bubble is applied. In the presence of the bubble in the droplet, the observed flow toward the center of the droplet is opposite to the flow observed in a droplet without the bubble. When the bubble is present, the evaporation process is retarded. Also, random motion is observed in the contact line region instead of the typical evaporation-driven flow toward the droplet edge. Once the bubble bursts, however, the total evaporation time decreases due to the change in the contact line characteristics. Moreover, the area of fringe patterns beneath the bubble increases with time. Discussed herein is a unique internal flow that has not been observed in nanofluid droplet evaporation.

Fabrication and Testing of Electrospun Polyurethane Blended with Chitosan Nanoparticles for Vascular Graft Applications.

PubMed

Subramaniam, Ranjeeta; Mani, Mohan Prasath; Jaganathan, Saravana Kumar

2018-04-26

In this study, a small vascular graft based on polyurethane (PU) blended with chitosan (Ch) nanoparticles was fabricated using electrospinning technique. Initially, the chitosan nanoparticles were synthesized using ionic gelation method. UV-Vis spectrophotometer confirmed the presence of synthesized Ch nanoparticles by exhibiting absorption peak at 288 nm and the Fourier-transform infrared spectroscopy (FTIR) analysis confirmed the existence of the chitosan. Further, the synthesized Ch nanoparticles showed size diameter in the range of 134 ± 58 nm as measured using ImageJ. In the electrospun PU/chitosan graft, the fiber diameter and pore size diameter was found to be reduced compared to the pure PU owing to incorporation of chitosan into PU matrix. The FTIR spectrum revealed the presence of chitosan in the prepared nanocomposite membrane by the formation of the hydrogen bond and peak shift of CH and NH stretching. Moreover, the contact angle measurements revealed that the prepared graft showed decreased contact angle indicating hydrophilic nature compared to the pristine PU. The cytocompatibility studies revealed the non-toxic behavior of the fabricated graft. Hence, the prepared graft exhibiting significant physiochemical and non-toxic properties may be a plausible candidate for cardiovascular graft applications.

[Enrichment of glycoproteins in human serum using concanavalin A-functionalized magnetic nanoparticles and identification by mass spectrometry].

PubMed

Li, Feng; Kang, Jingwu

2014-04-01

Biomedical sciences, and in particular biomarker research, demand efficient glycoprotein enrichment platforms. Herein novel magnetic nanoparticles with an average size around 135 nm in diameter were prepared for the enrichment of glycoproteins in human serum. The prepared magnetic nanoparticles possessed uniform core/shell/shell structure which was composed of 8 nm magnetite internal core and double layers consisting of silica and poly glycidyl methacrylate (GMA). The latter was constructed by seed polymerization. Modified by a polyethylene hydrophilic linker, it made the surfaces of the magnetic nanoparticles highly hydrophilic so as to reduce the nonspecific adsorption of proteins. We examined affinity purification of glycoprotein in diluted human serum using our prepared magnetic nanoparticles with immobilization of concanavalin A (MNP @ ConA). The enriched proteins were reduced, alkylated and digested with trypsin. These peptides then were separated by offline two-dimensional chromatography. Protein identification was realized with nano-high performance liquid chromatography-orbitrap mass spectrometry. A total of 80 proteins were identified, among them 76 proteins were found to be glycoproteins by use of bioinformatic tools. /3-2-Glycoprotein 1 present in serum at low mass concentration around 0.000 01 g/L was also identified. This demonstrates the capability of magnetic nanoparticle for recovering minute amounts of glycoproteins from a fluid exhibiting a dynamic concentration range more than 12 orders of magnitude. Overall, MNP @ ConA has been proven to be an efficient alternative to currently available immobilization supports.

Synthesis and Applications of Multimodal Hybrid Albumin Nanoparticles for Chemotherapeutic Drug Delivery and Photothermal Therapy Platforms

NASA Astrophysics Data System (ADS)

Peralta, Donna V.

Progress has been made in using human serum albumin nanoparticles (HSAPs) as carrier systems for targeted treatment of cancer. Human serum albumin (HSA), the most abundant human blood protein, can form HSAPs via a desolvation and crosslinking method, with the size of the HSAPs having crucial importance for drug loading and in vivo performance. Gold nanoparticles have also gained medicinal attention due to their ability to absorb near-infrared (NIR) light. These relatively non-toxic particles offer combinational therapy via imaging and photothermal therapy (PPTT) capabilities. A desolvation and crosslinking approach was employed to encapsulate gold nanoparticles (AuNPs), hollow gold nanoshells (AuNSs), and gold nanorods (AuNRs), into efficiently sized HSAPs for future tumor heat ablation via PPTT. The AuNR-HSAPs, AuNP-HSAPs and AuNS-HSAPs had average particle diameters of 222 +/- 5, 195 +/- 9 and 156 +/- 15, respectively. We simultaneously encapsulated AuNRs and the anticancer drug paclitaxel (PAC), forming PAC-AuNR-HSAPs with overall average particle size of 299 +/- 6 nm. Loading of paclitaxel into PAC-AuNR-HSAPs reached 3microg PAC/mg HSA. PAC-AuNR-HSAPs experienced photothermal heating of 46 °C after 15 minutes of NIR laser exposure; the temperature necessary to cause severe cellular hyperthermia. There was a burst release of paclitaxel up to 188 ng caused by the irradiation session, followed by a temporal drug release. AuNR-HSAPs were tested for ablation of renal cell carcinoma using NIR irradiation in vitro. Particles created with the same amount of AuNRs, but varying HSA (1, 5 or 20 mg) showed overall particle size diameters 409 +/- 224, 294 +/- 83 and 167 +/- 4 nm, respectively. Increasing HSAPs causes more toxicity under non-irradiated treatment conditions: AuNR-HSAPs with 20 mg versus 5 mg HSA caused cell viability of 64.5% versus 87%, respectively. All AuNR-HSAPs batches experienced photothermal heating above 42 °C. Coumarin-6, was used to visualize the cellular uptake of AuNR-HSAPs via fluorescence microscopy. Finally, camptothecin (CPT) an antineoplastic agent and BACPT (7-butyl-10-aminocamptothecin) were loaded into HSAPs to combat their aqueous insolubility. BACPT-HSAPs loaded up to 5.25 micrograms BACPT/ mg of HSA. CPT encapsulation could not be determined. BACPT-HSAPs and CPT-HSAPs showed cytotoxicity to human sarcoma cells in vitro. Key words: Hybrid Nanoparticles, Photothermal Therapy, Gold Nanomaterials, Drug Delivery, Combinational Cancer Therapies, Materials, Human Serum Albumin, Colloidal Carriers.

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

NASA Astrophysics Data System (ADS)

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

2015-12-01

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

Physical-chemical properties of nanocomposites based on poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and titanium dioxide nanoparticles

NASA Astrophysics Data System (ADS)

Braga, Natália F.; da Silva, Ana Paula; Moraes Arantes, Tatiane; Lemes, Ana Paula; Cristovan, Fernando Henrique

2018-01-01

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) was reinforced with titanium dioxide (TiO2) in concentrations of 1.0%, 2.5% and 5.0% (m/m) to produce nanocomposites by the solvent casting technique. TiO2 was synthesized by a hydrothermal treatment to produce nanoparticles. The nanostructure of the nanoparticles was studied by x-ray diffraction analysis (XRD) and transmission electron microscopy (TEM). The XRD confirmed TiO2 crystalline nanoparticles, with a mixture of anatase and rutile phases. Through TEM analysis, the formation of TiO2 nanorod agglomerates with an average diameter and length of 40 and 12 nm, respectively, was observed. The thermal and mechanical properties of the pure PHBV and nanocomposite films were characterized by differential scanning calorimetry (DSC) and dynamic mechanical analysis. The DSC analysis showed that the glass transition temperature decreased with the inclusion of TiO2 in the PHBV matrix in relation to pure PHBV. The results of biodegradation assays for the PHBV and nanocomposites in an aqueous medium and in soil showed morphological and structural changes for all samples, indicating a high biodegradation rate for this material. The most important conclusion is that the biodegradation of the PHBV was not affected by the addition of nanoparticles, thus enabling the use of nanocomposites in applications requiring biodegradable materials.

Green synthesis and antibacterial effects of aqueous colloidal solutions of silver nanoparticles using camomile terpenoids as a combined reducing and capping agent.

PubMed

Parlinska-Wojtan, Magdalena; Kus-Liskiewicz, Małgorzata; Depciuch, Joanna; Sadik, Omowunmi

2016-08-01

Green synthesis method using camomile extract was applied to synthesize silver nanoparticles to tune their antibacterial properties merging the synergistic effect of camomile and Ag. Scanning transmission electron microscopy revealed that camomile extract (CE) consisted of porous globular nanometer sized structures, which were a perfect support for Ag nanoparticles. The Ag nanoparticles synthesized with the camomile extract (AgNPs/CE) of 7 nm average sizes, were uniformly distributed on the CE support, contrary to the pure Ag nanoparticles synthesized with glucose (AgNPs/G), which were over 50 nm in diameter and strongly agglomerated. The energy dispersive X-ray spectroscopy chemical analysis showed that camomile terpenoids act as a capping and reducing agent being adsorbed on the surface of AgNPs/CE enabling their reduction from Ag(+) and preventing them from agglomeration. Fourier transform infrared and ultraviolet-visible spectroscopy measurements confirmed these findings, as the spectra of AgNPs/CE, compared to pure CE, did not contain the 1109 cm(-1) band, corresponding to -C-O groups of terpenoids and the peaks at 280 and 320 nm, respectively. Antibacterial tests using four bacteria strains showed that the AgNPs/CE performed five times better compared to CE AgNPs/G samples, reducing totally all the bacteria in 2 h.

Green synthesis of silver nanoparticles using Achillea biebersteinii flower extract and its anti-angiogenic properties in the rat aortic ring model.

PubMed

Baharara, Javad; Namvar, Farideh; Ramezani, Tayebe; Hosseini, Nasrin; Mohamad, Rosfarizan

2014-04-15

Silver nanoparticles display unique physical and biological properties which have attracted intensive research interest because of their important medical applications. In this study silver nanoparticles (Ab.Ag-NPs) were synthesized for biomedical applications using a completely green biosynthetic method using Achillea biebersteinii flowers extract. The structure and properties of Ab.Ag-NPs were investigated using UV-visible spectroscopic techniques, transmission electron microscopy (TEM), zeta potential and energy dispersive X-ray spectrometers (EDS). The UV-visible spectroscopic analysis showed the absorbance peak at 460 nm, which indicates the synthesis of silver nanoparticles. The average particle diameter as determined by TEM was found to be 12±2 nm. The zeta potential analysis indicated that Ab.Ag-NPs have good stability EDX analysis also exhibits presentation of silver element. As angiogenesis is an important phenomenon and as growth factors imbalance in this process causes the acceleration of several diseases including cancer, the anti-angiogenic properties of Ab.Ag-NPs were evaluated using the rat aortic ring model. The results showed that Ab.Ag-NPs (200 μg/mL) lead to a 50% reduction in the length and number of vessel-like structures. The synthesized silver nanoparticles from the Achillea biebersteinii flowers extract, which do not involve any harmful chemicals were well-dispersed and stabilized through this green method and showed potential therapeutic benefits against angiogenesis.

Effects of chlorine and other water quality parameters on the release of silver nanoparticles from a ceramic surface.

PubMed

Bielefeldt, Angela R; Stewart, Michael W; Mansfield, Elisabeth; Scott Summers, R; Ryan, Joseph N

2013-08-01

A quartz crystal microbalance was used to determine the effects of different water quality parameters on the detachment of silver nanoparticles from surfaces representative of ceramic pot filters (CPFs). Silver nanoparticles stabilized with casein were used in the experiments. The average hydrodynamic diameter of the nanoparticles ranged from 20 nm to 100 nm over a pH range of 6.5-10.5. The isoelectric point was about 3.5 and the zeta potential was -45 mV from pH 4.5 to 9.5. The silver nanoparticles were deposited onto silica surfaces and a quartz crystal microbalance was used to monitor silver release from the surface. At environmentally relevant ranges of pH (4.8-9.3), ionic strength (0 and 150 mol/m(3) NaNO3 or 150 mol/m(3) Ca(NO3)2), and turbidity (0 and 51.5 NTU kaolin clay), the rates of silver release were similar. A high concentration of sodium chloride and bacteria (Echerichia coli in 10% tryptic soy broth) caused rapid silver release. Water containing sodium hypochlorite removed 85% of the silver from the silica surface within 3 h. The results suggest that contact between CPFs and prechlorinated water or bleach CPF cleaning should be avoided. Copyright © 2013 Elsevier Ltd. All rights reserved.

Pleuropterus multiflorus (Hasuo) mediated straightforward eco-friendly synthesis of silver, gold nanoparticles and evaluation of their anti-cancer activity on A549 lung cancer cell line.

PubMed

Castro-Aceituno, Verónica; Abbai, Ragavendran; Moon, Seong Soo; Ahn, Sungeun; Mathiyalagan, Ramya; Kim, Yu-Jin; Kim, Yeon-Ju; Yang, Deok Chun

2017-09-01

Pleuropterus multiflorus (Hasuo) is a widely used medicinal plant in Korea and China for treating amnesia, isnomia, heart throbbing etc. With the constructive idea of promoting the wide-spread usage of P. multiflorus, we propose its indirect usage in the form of biologically active silver (Pm-AgNPs) and gold nanoparticles (Pm-AuNPs). The synthesized nanoparticles were predominantly spherical, crystalline with the Z-average hydrodynamic diameter of 274.8nm and 104.8nm respectively. Also, proteins and phenols were identified as the major players involved in their synthesis and stability. Further, Pm-AgNPs at 25μg/mL were significantly cytotoxic to lung cancer cells, whereas, Pm-AuNPs were not cytotoxic to both normal keratinocyte and lung cancer cells even at 100μg/mL. In addition, further evaluation of the anti-cancer activity of these new nanoparticles, such as migration and apoptosis, shown that Pm-AgNPs have a potential therapeutic effect on A549 lung cancer cell treatment. To the best of our knowledge, this is the first report dissecting out the ability of the endemic P. multiflorus for the synthesis of bioactive silver and gold nanoparticle which would open up doors for its extensive usage in medicinal field. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

INFLUENCE OF LIPOPHILIC AND HYDROPHILIC CO-MONOMERS ON THE HYDRODYNAMIC DIAMETER OF THERMOSENSITIVE NIPA DERIVATIVES FOR THERMALLY CONTROLLED DRUG DELIVERY.

PubMed

Musial, Witold; Gasztych, Monika; Kokol, Vanja; Mucha, Igor; Makanis, Aleksandra; Kolodziejczyk, Woiciech; Gola, Agnieszka

2017-01-01

For modem drug delivery, new drug carriers sensitive to various factors and with size in the range of micro- and nanometers are required. The aim of this work was to evaluate the influence of hydrophilic and hydrophobic co-monomers on the hydrodynamic diameter of three co-polymers of N-isopropylacrylamide (NIPA) nanogels synthesized at 70*C in the presence of potassium persulfate (KPS) as the initiator and N.N'-methylene bis-acrylamide (MBA) as the cross-linker. The first batch of nanoparticles was synthesized without co-monomer, whereas poly(ethylene glycol) methyl ether acrylate (PEG-MEA), and N-teii-butylacrylamide (NTB), were implemented as co-monomers for the second and third batch. Hydrodynamic diameter of nanoparticles was in the range 550-800 rn. The compositions of the synthesized co-polymer nanoparticles were con- firmed via IR and NMR analyses. The SFPP conditions resulted in hydrodynamic diameters ranging from approximately 550 to 800 nm at temperatures lower than the volume phase transition temperature (VPTT) and diameters ranging from 250 to 600 nm at temperatures above the VPTT, where the VPTT was between 26 and 41'C. The polydispersity index (PDI) showed a maximum or a minimum value at the VPTT, which was an important indicator of the volume phase transition. According to the PDI observation during thermal cycling, the addition of NTB into the polymeric chain resulted in maximal values of the PDI at the VPIT, similar to the case of nanoparticles without any additional co-monomers. In contrast, in the case of PEG-MEA, the PDI presented a minimal value. Dynamic light scattering (DLS) volume measurements, performed simultaneously with spectral methods, may lead to a fast evaluation of nanoparticles prepared by SFPP.

Quantitative characterization of gold nanoparticles by field-flow fractionation coupled online with light scattering detection and inductively coupled plasma mass spectrometry.

PubMed

Schmidt, Bjørn; Loeschner, Katrin; Hadrup, Niels; Mortensen, Alicja; Sloth, Jens J; Koch, Christian Bender; Larsen, Erik H

2011-04-01

An analytical platform coupling asymmetric flow field-flow fractionation (AF(4)) with multiangle light scattering (MALS), dynamic light scattering (DLS), and inductively coupled plasma mass spectrometry (ICPMS) was established and used for separation and quantitative determination of size and mass concentration of nanoparticles (NPs) in aqueous suspension. Mixtures of three polystyrene (PS) NPs between 20 and 100 nm in diameter and mixtures of three gold (Au) NPs between 10 and 60 nm in diameter were separated by AF(4). The geometric diameters of the separated PS NPs and the hydrodynamic diameters of the Au and PS NPs were determined online by MALS and DLS, respectively. The three separated Au NPs were quantified by ICPMS and recovered at 50-95% of the injected masses, which ranged between approximately 8-80 ng of each nanoparticle size. Au NPs adhering to the membrane in the separation channel was found to be a major cause for incomplete recoveries. The lower limit of detection (LOD) ranged between 0.02 ng Au and 0.4 ng Au, with increasing LOD by increasing nanoparticle diameter. The analytical platform was applied to characterization of Au NPs in livers of rats, which were dosed with 10 nm, 60 nm, or a mixture of 10 and 60 nm nanoparticles by intravenous injection. The homogenized livers were solubilized in tetramethylammonium hydroxide (TMAH), and the recovery of Au NPs from the livers amounted to 86-123% of their total Au content. In spite of successful stabilization with bovine serum albumin even in alkaline medium, separation of the Au NPs by AF(4) was not possible due to association with undissolved remains of the alkali-treated liver tissues as demonstrated by electron microscopy images.

High Pressure Structure and Electrical Resistance Measurements on Cadmium Sulfide Nanoparticles

NASA Astrophysics Data System (ADS)

Montgomery, J. M.; Stemshorn, A. K.; Stanishevsky, A.; Vohra, Y. K.; Weir, S. T.

2010-03-01

Room-temperature four-probe electrical resistance and synchrotron x-ray diffraction measurements have been performed on dried and aqueous suspensions of CdS nanoparticles (25 nm in diameter) to 35 GPa. Nanoparticles used in these experiments were synthesized using the reaction between a cadmium salt and thiourea under hydrothermal conditions without using any surfactants. While the x-ray structure data confirms the irreversible wurtzite -> rocksalt transition seen at 2.5 GPa in bulk CdS, the corresponding resistance drop was not observed in the measured range, indicating that the nanoparticle boundaries may prevent electronic communication between particles. Further studies on dry and aqueous 10 nm nano-spheres and 9 nm diameter nano-rods are planned, and the results of these experiments will be presented.

Magnetic properties of superparamagnetic nanoparticles loaded into silicon nanotubes.

PubMed

Granitzer, Petra; Rumpf, Klemens; Gonzalez, Roberto; Coffer, Jeffery; Reissner, Michael

2014-01-01

In this work, the magnetic properties of silicon nanotubes (SiNTs) filled with Fe3O4 nanoparticles (NPs) are investigated. SiNTs with different wall thicknesses of 10 and 70 nm and an inner diameter of approximately 50 nm are prepared and filled with superparamagnetic iron oxide nanoparticles of 4 and 10 nm in diameter. The infiltration process of the NPs into the tubes and dependence on the wall-thickness is described. Furthermore, data from magnetization measurements of the nanocomposite systems are analyzed in terms of iron oxide nanoparticle size dependence. Such biocompatible nanocomposites have potential merit in the field of magnetically guided drug delivery vehicles. 61.46.Fg; 62.23.Pq; 75.75.-c; 75.20.-g.

One-pot, exchange-free, room-temperature synthesis of sub-10 nm aqueous, noninteracting, and stable zwitterated iron oxide nanoparticles.

PubMed

Estephan, Zaki G; Hariri, Hanaa H; Schlenoff, Joseph B

2013-02-26

Stable aqueous dispersions of superparamagnetic iron oxide nanoparticles were synthesized in one step in the presence of a zwitterionic siloxane as the stabilizing/capping/solubilizing ligand. The hydrodynamic diameter of the particles was tuned by controlling the concentration of zwitterion siloxane, which ultimately yielded monodisperse nanoparticles small enough for renal filtration (<6 nm diameter). The zwitterated nanoparticles were readily dispersed and stable in aqueous media in the pH range 6-9 but exhibited lower magnetization values than nonzwitterated materials due to amorphous content and spin canting, typical for particles of such size. Turbidimetry and light scattering studies revealed no interaction between the particles and proteins, suggesting the materials will circulate well in vivo.

Biosynthesis of silver nanoparticles from Cavendish banana peel extract and its antibacterial and free radical scavenging assay: a novel biological approach

NASA Astrophysics Data System (ADS)

Kokila, T.; Ramesh, P. S.; Geetha, D.

2015-12-01

Biosynthesis of metallic silver nanoparticles has now become an alternative to physical and chemical approaches. In the present study, silver nanoparticles (AgNPs) were synthesized from Cavendish banana peel extract (CBPE) and characterized by UV-visible spectroscopy, X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, Atomic force microscopy (AFM), Field emission scanning electronic microscope (FESEM), Dynamic light scattering (DLS) and zeta potential (ZP). The AgNPs formation was confirmed by UV-visible spectroscopy through color conversion due to surface plasma resonance band at 430 nm. The effect of pH on nanoparticle synthesis was determined by adjusting the various pH of the reaction mixtures. The crystalline nature of nanoparticles was confirmed from the XRD pattern, and the grain size was found to be around 34 nm. To identify the compounds responsible for the bioreduction of Ag+ ion and the stabilization of AgNPs produced, the functional group present in Cavendish banana peel extract was investigated using FTIR. AFM has proved to be very helpful in determining morphological features and the diameter of AgNPs in the range of 23-30 nm was confirmed by FESEM. DLS studies revealed that the average size of AgNPs was found to be around 297 nm. Zeta potential value for AgNPs obtained was -11 mV indicating the moderate stability of synthesized nanoparticles. The antibacterial activity of the nanoparticles was studied against Gram-positive and Gram-negative bacteria. Biosynthesized AgNPs showed a strong DPPH radical and ABTS scavengers compared to the aqueous peel extract of Cavendish banana.

Synthesis and property investigation of metal-based nanomaterials for biotechnological applications

NASA Astrophysics Data System (ADS)

Darsanasiri, Nalin Dammika

Luminescent lanthanide-based materials have drawn recent interest due to their applications in in vitro cellular imaging. Sensitive biological analysis requires optical labels with high water dispersibility & stability and excellent luminescent properties. Most literature reported lanthanide complexes with high luminescence intensity are hydrophobic and unstable, limiting their biological applications. This project was designed to incorporate a highly luminescent lanthanide beta-diketonate complex in a silica nanoparticle. Eu(btfa)3dmph complex was synthesized, which exhibits red luminescence at 614 nm with a narrow (15 nm) full with half-maximum (btfa=4,4,4-trifluoro-1-phenyl-1,3-butanedione, dmph=4,7-dimethyl,1,10-phenanthroline). A synthetic procedure was optimized to incorporate the Eu-complex in a silica-based nanoparticle with an average particle diameter of 36 nm. Eu-complex based silica nanoparticles exhibit high stability and water-dispersibility with a luminescence quantum yield of 10 %. The nanoparticles showed antimicrobial activity against clinically important E.coli, S.aureus and S.epidermidis. Synthesis, materials characterization, and antimicrobial studies of the complex and the nanoparticles was discussed in the first part of this thesis. Nanotechnology is emerging as a new interdisciplinary field combining biology, chemistry, physics, and material science. Recent advances promise developments in the synthesis, modification and practical applications of polymer-coated manganese (Mn)-based zinc oxide (ZnO) nanoparticles (NPs). The size distribution, shape, and surface modification of metal-based ZnO nanoparticles are the key factors determining their specific physical properties. Due to the strong antibacterial properties and low toxicity towards mammalian cells, ZnO NPs have been successfully used in a wide range of applications including wound dressing, protective clothing, antibacterial surfaces, food preservation, and cosmetics as biocidal and disinfecting agents. In this study, cotton textiles with antimicrobial activity were developed by incorporating polymer-coated Mn-doped ZnO nanoparticles. Antimicrobial potential of synthesized Mn-doped zinc oxide (ZnO) nanoparticles against two bacteria strains ( Escherichia coli as Gram-negative bacteria, Staphylococcus aureus as Gram-positive bacteria) in liquid and solid phases was studied in this work. Polymer-coated Mn-doped ZnO nanoparticles were prepared by the modified co-precipitation method. Characterization of the nanoparticles was carried out using Ultra-violet visible spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray powder diffraction (XRD). The average particle size of the nanoparticles was found to be less than 15 nm. The antibacterial activity of the nanoparticles was evaluated using minimum inhibitory concentration (MIC) and agar diffusion method. Disk diffusion studies revealed that the nanoparticles have excellent antimicrobial activity against E.coli and S.aureus bacterial species. Therefore, it was concluded that the polymer-coated Mn-doped ZnO nanoparticles were excellent antibacterial agents with potential clinical applications.

Enhanced tolerance and antitumor efficacy by docetaxel-loaded albumin nanoparticles.

PubMed

Tang, Xiaolei; Wang, Guijun; Shi, Runjie; Jiang, Ke; Meng, Lingtong; Ren, Hao; Wu, Jinhui; Hu, Yiqiao

2016-10-01

Docetaxel is one of the most active chemotherapeutic agents for cancer treatment. The traditional docetaxel injection (TAXOTERE®) is currently formulated in the surfactant polysorbate 80, which has been associated with severe adverse reactions. To avoid the use of polysorbate 80 as well as to reduce the systemic toxicity of docetaxel, in this study, docetaxel-loaded albumin nanoparticles were fabricated by a novel simple self-assembly method. The resulting nanoparticles showed a mean diameter size of 150 nm. After being encapsulated into nanoparticles, docetaxel displayed similar cytotoxicity to traditional injection. Since polysorbate 80 was not involved in nanoparticles, the hemolysis was completely eliminated. The maximal tolerance dose of nanoparticles was also increased, which allowed a higher dose to be safely intravenously injected and produced ideal antitumor effects. The 150 nm diameter also allowed the nanoparticles to accumulate in tumor tissue via the enhanced permeability and retention effect. The passive targeting ability further caused the higher antitumor effects of nanoparticles than that of traditional injection at the same dose (7.5 mg/kg). Therefore, docetaxel-loaded albumin nanoparticles fabricated by our strategy showed higher promise in their safety and effectiveness than the traditional docetaxel injection.

Synthesis and characterization of pHLIP® coated gold nanoparticles.

PubMed

Daniels, Jennifer L; Crawford, Troy M; Andreev, Oleg A; Reshetnyak, Yana K

2017-07-01

Novel approaches in synthesis of spherical and multispiked gold nanoparticles coated with polyethylene glycol (PEG) and pH Low Insertion Peptide (pHLIP ® ) were introduced. The presence of a tumor-targeting pHLIP ® peptide in the nanoparticle coating enhances the stability of particles in solution and promotes a pH-dependent cellular uptake. The spherical particles were prepared with sodium citrate as a gold reducing agent to form particles of 7.0±2.5 nm in mean metallic core diameter and ∼43 nm in mean hydrodynamic diameter. The particles that were injected into tumors in mice (21 µg of gold) were homogeneously distributed within a tumor mass with no staining of the muscle tissue adjacent to the tumor. Up to 30% of the injected gold dose remained within the tumor one hour post-injection. The multispiked gold nanoparticles with a mean metallic core diameter of 146.0±50.4 nm and a mean hydrodynamic size of ~161 nm were prepared using ascorbic acid as a reducing agent and disk-like bicelles as a template. Only the presence of a soft template, like bicelles, ensured the appearance of spiked nanoparticles with resonance in the near infrared region. The irradiation of spiked gold nanoparticles by an 805 nm laser led to the time- and concentration-dependent increase of temperature. Both pHLIP ® and PEG coated gold spherical and multispiked nanoparticles might find application in radiation and thermal therapies of tumors.

Preparation, characterization and in vitro release study of carvacrol-loaded chitosan nanoparticles.

PubMed

Keawchaoon, Lalita; Yoksan, Rangrong

2011-05-01

The fabrication of carvacrol-loaded chitosan nanoparticles was achieved by a two-step method, i.e., oil-in-water emulsion and ionic gelation of chitosan with pentasodium tripolyphosphate. The obtained particles possessed encapsulation efficiency (EE) and loading capacity (LC) in the ranges of 14-31% and 3-21%, respectively, when the initial carvacrol content was 0.25-1.25 g/g of chitosan. The individual particles exhibited a spherical shape with an average diameter of 40-80 nm, and a positively charged surface with a zeta potential value of 25-29 mV. The increment of initial carvacrol content caused a reduction of surface charge. Carvacrol-loaded chitosan nanoparticles showed antimicrobial activity against Staphylococcus aureus, Bacillus cereus and Escherichia coli with an MIC of 0.257 mg/mL. The release of carvacrol from chitosan nanoparticles reached plateau level on day 30, with release amounts of 53% in acetate buffer solution with pH of 3, and 23% and 33% in phosphate buffer solutions with pH of 7 and 11, respectively. The release mechanism followed a Fickian behavior. The release rate was superior in an acidic medium to either alkaline or neutral media, respectively. Copyright © 2011 Elsevier B.V. All rights reserved.

Development and Application of a Label-Free Fluorescence Method for Determining the Composition of Gold Nanoparticle–Protein Conjugates

PubMed Central

Sotnikov, Dmitriy V.; Zherdev, Anatoly V.; Dzantiev, Boris B.

2014-01-01

A method was developed for determining the composition of the conjugates between gold nanoparticles and proteins based on the intrinsic fluorescence of unbound protein molecules. The fluorescence was evaluated after separation of the conjugates from the reaction mixture by centrifugation. Gold nanoparticles obtained using the citrate technique (average diameter 24 nm) were conjugated at pH 5.4 with the following four proteins: human immunoglobulin G (IgG), bovine serum albumin (BSA), recombinant streptococcal protein G (protein G), and Kunitz-type soybean trypsin inhibitor (STI). The compositions of these conjugates were determined using the developed method. The conjugate compositions were dependent on the concentration of the added protein, and in all cases reached saturation. The equilibrium dissociation constants of the gold nanoparticle conjugates with IgG, BSA, protein G, STI in the initial section of the concentration dependence curve were 4, 6, 10, and 15 nM, respectively. Close to saturation, the corresponding values were 25, 76, 175, and 100 nM, respectively. The maximal binding capacities of a single gold nanoparticle for IgG, BSA, Protein G, and STI were 52, 90, 500, and 550, respectively, which agrees well with the hypothesis of monolayer immobilization. PMID:25561238

Effects of gold nanoparticles on the photophysical and photosynthetic parameters of leaves and chloroplasts.

PubMed

Torres, Rocio; Diz, Virginia E; Lagorio, M Gabriela

2018-04-18

Effects of gold nanoparticles (average diameter: 10-14 nm) on leaves and chloroplasts have been studied. Gold nanoparticles (AuNPs) quenched significantly chlorophyll fluorescence when introduced both in intact leaves and isolated chloroplasts. Additionally, the fluorescence spectra corrected for light re-absorption processes showed a net decrease in the fluorescence ratio calculated as the quotient between the maximum fluorescence at 680 and 735 nm. This fact gave evidence for a reduction in the fluorescence emission of the PSII relative to that of the PSI. Strikingly, the photosynthetic parameters derived from the analysis of the slow phase of Kautsky's kinetics, the rate of oxygen evolution and the rate of photo-reduction of 2,6-dichlorophenolindophenol were increased in the presence of AuNPs indicating an apparent greater photosynthetic capacity. The observed results were consistent with an electron transfer process from the excited PSII, which was thermodynamically possible, and which competed with both the electron transport process that initiated photosynthesis and the deactivation of the excited PSII by fluorescence emission. Additionally, it is here explained, in terms of a completely rational kinetic scheme and their corresponding algebraic expressions, why the photosynthetic parameters and the variable and non-variable fluorescence of chlorophyll are modified in a photosynthetic tissue containing gold nanoparticles.

Synthesis of nano-sized silicon from natural halloysite clay and its high performance as anode for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Zhou, Xiangyang; Wu, Lili; Yang, Juan; Tang, Jingjing; Xi, Lihua; Wang, Biao

2016-08-01

Recently, nanostructured Si has been intensively studied as a promising anode candidate for lithium ion batteries due to its ultrahigh capacity. However, the downsizing of Si to nanoscale dimension is often impeded by complicated and expensive methods. In this work, natural halloysite clay was utilized for the production of Si nanoparticles through selective acid etching and modified magnesiothermic reduction processes. The physical and chemical changes of these samples during the various processes have been analyzed. The as-prepared Hsbnd Si from halloysite clay is composed of many interconnected Si nanoparticles with an average diameter of 20-50 nm. Owing to the small size and porous nature, the Hsbnd Si nanoparticles exhibit a satisfactory performance as an anode for lithium ion batteries. Without further modification, a stable capacity over 2200 mAh g-1 at a rate of 0.2 C after 100 cycles and a reversible capacity above 800 mAh g-1 at a rate of 1 C after 1000 cycles can be obtained. As a result, this synthetic route is cost-effective and can be scaled up for mass production of Si nanoparticles, which may facilitate valuable utilization of halloysite clay and further commercial application of Si-based anode materials.

Thermal dewetting with a chemically heterogeneous nano-template for self-assembled L1(0) FePt nanoparticle arrays.

PubMed

Wang, Liang-Wei; Cheng, Chung-Fu; Liao, Jung-Wei; Wang, Chiu-Yen; Wang, Ding-Shuo; Huang, Kuo-Feng; Lin, Tzu-Ying; Ho, Rong-Ming; Chen, Lih-Juann; Lai, Chih-Huang

2016-02-21

A design for the fabrication of metallic nanoparticles is presented by thermal dewetting with a chemically heterogeneous nano-template. For the template, we fabricate a nanostructured polystyrene-b-polydimethylsiloxane (PS-b-PDMS) film on a Si|SiO2 substrate, followed by a thermal annealing and reactive ion etching (RIE) process. This gives a template composed of an ordered hexagonal array of SiOC hemispheres emerging in the polystyrene matrix. After the deposition of a FePt film on this template, we utilize the rapid thermal annealing (RTA) process, which provides in-plane stress, to achieve thermal dewetting and structural ordering of FePt simultaneously. Since the template is composed of different composition surfaces with periodically varied morphologies, it offers more tuning knobs to manipulate the nanostructures. We show that both the decrease in the area of the PS matrix and the increase in the strain energy relaxation transfer the dewetted pattern from the randomly distributed nanoparticles into a hexagonal periodic array of L10 FePt nanoparticles. Transmission electron microscopy with the in situ heating stage reveals the evolution of the dewetting process, and confirms that the positions of nanoparticles are aligned with those of the SiOC hemispheres. The nanoparticles formed by this template-dewetting show an average diameter and center-to-center distance of 19.30 ± 2.09 nm and 39.85 ± 4.80 nm, respectively. The hexagonal array of FePt nanoparticles reveals a large coercivity of 1.5 T, much larger than the nanoparticles fabricated by top-down approaches. This approach offers an efficient pathway toward self-assembled nanostructures in a wide range of material systems.

Interaction of gold nanoparticles with nanosecond laser pulses: Nanoparticle heating

NASA Astrophysics Data System (ADS)

Nedyalkov, N. N.; Imamova, S. E.; Atanasov, P. A.; Toshkova, R. A.; Gardeva, E. G.; Yossifova, L. S.; Alexandrov, M. T.; Obara, M.

2011-04-01

Theoretical and experimental results on the heating process of gold nanoparticles irradiated by nanosecond laser pulses are presented. The efficiency of particle heating is demonstrated by in-vitro photothermal therapy of human tumor cells. Gold nanoparticles with diameters of 40 and 100 nm are added as colloid in the cell culture and the samples are irradiated by nanosecond pulses at wavelength of 532 nm delivered by Nd:YAG laser system. The results indicate clear cytotoxic effect of application of nanoparticle as more efficient is the case of using particles with diameter of 100 nm. The theoretical analysis of the heating process of nanoparticle interacting with laser radiation is based on the Mie scattering theory, which is used for calculation of the particle absorption coefficient, and two-dimensional heat diffusion model, which describes the particle and the surrounding medium temperature evolution. Using this model the dependence of the achieved maximal temperature in the particles on the applied laser fluence and time evolution of the particle temperature is obtained.

Determination of Conjugation Efficiency of Antibodies and Proteins to the Superparamagnetic Iron Oxide Nanoparticles by Capillary Electrophoresis with Laser-Induced Fluorescence Detection

NASA Astrophysics Data System (ADS)

Wang, Fu-Hua; Yoshitake, Takashi; Kim, Do-Kyung; Muhammed, Mamoun; Bjelke, Börje; Kehr, Jan

2003-04-01

The method based on capillary electrophoresis with laser-induced fluorescence detection (CE/LIF) was developed for determination of magnetic iron oxide nanoparticles (hydrodynamic diameters of 100 nm) functionalized with molecules containing primary amino groups. The magnetic nanoparticles with carboxylic or aminopropyl-trimethoxysilane groups at their surface were conjugated to the model proteins (bovine serum albumin, BSA; streptavidin or goat anti-rabbit immunoglobulin G, IgG) using carbodiimide as a zero-length cross-linker. The nanoparticle-protein conjugates (hydrodynamic diameter 163-194 nm) were derivatized with naphthalene-2,3-dicarboxaldehyde reagent and separated by CE/LIF with a helium-cadmium laser (excitation at 442 nm, emission at 488 nm). The separations were carried out by using a fused-silica capillary (effective length 48 cm, inner diameter 75 um) and 100 mM sodium borate buffer (pH 9.2), the potential was 30 kV. The detection limit for BSA-conjugate was 1.3 pg/10 nl, i.e. about 20 amol. The present method provides an efficient and fast tool for sensitive determination of the efficacy of biomolecular functionalization of magnetic nanoparticles. The CE/LIF technique requires only negligible sample volumes for analysis, which is especially suitable for controlling the process of preparation of functionalized nanoparticles with unique properties aimed to be used for diagnostic or therapeutic purposes.

Multicore Magnetic Nanoparticles Coated with Oligomeric Micelles: Characterization and Potential for the Extraction of Contaminants over a Wide Polarity Range.

PubMed

Naous, Mohamed; García-Gómez, Diego; López-Jiménez, Francisco José; Bouanani, Farida; Lunar, María Loreto; Rubio, Soledad

2017-01-17

Oligomeric micelles from sodium undecylenate (oSUD) were chemisorbed to magnetic iron oxide nanoparticles (MNPs) through a single-step synthetic route involving the simultaneous nanoparticle formation and functionalization in an aqueous medium. The resulting spherical nanoparticles (MNPs-oSUD) consisted of a concatenation of iron oxide cores, with an average size of 7.7 nm, bound by oSUD micelles (particle average diameter of ca. 200 nm). Micellar coverage was ∼50% of the MNP-oSUD (by weight) and offered multiple retention mechanisms (e.g., dispersion, hydrogen bonding, polar, and ionic) for solute solubilization while keeping it intact during analyte elution. The high density of micelles and variety of interactions provided by this sorbent rendered it highly efficient for the extraction of aromatic amines in a wide polarity range (log K ow values from -0.80 to 4.05) from textiles, urine, and wastewater. Extraction took 5 min, no cleanup or evaporation of the extracts was needed and the method, based on LC-MS/MS quantitation, proved matrix-independent. Recoveries for 17 aromatic amines in samples were in the range of 93%-123% while those with negative log K ow values were in the range of 69%-87%. Detection limits for aromatic amines in textiles (0.007-2 mg kg -1 ) were well below the limits legislated by the European Union (EU) (30 mg kg -1 ) and those in urine and wastewater (0.004-1.5 μg L -1 ) were at the level usually found in real-world applications. All the analyzed samples were positive in aromatic amines. The easy synthesis and excellent extraction properties of MNPs-oSUD anticipate their high potential not only for multiresidue analysis but also in other fields such as water remediation.

The effect of microemulsion composition on the morphology of Pd nanoparticles deposited at the surface of TiO2 and photoactivity of Pd-TiO2

NASA Astrophysics Data System (ADS)

Długokęcka, Marta; Łuczak, Justyna; Polkowska, Żaneta; Zaleska-Medynska, Adriana

2017-05-01

A series of microemulsion (ME) system, constituted by different water to surfactant molar ratios (Wo) and oil to surfactant mass ratios (S), have been applied for Pd-TiO2 preparation. The effect of ME properties on the morphology of Pd nanoparticles formed at TiO2 surface and an effect of Pd size and distribution on the surface and photocatalytic properties of Pd-TiO2 were investigated. Microemulsion systems were characterized by means of viscosity, density, dynamic light scattering as well as surface tension measurements to find a correlation between the conditions of Pd nanoparticles formation, their morphology and photocatalyst features. The photocatalysts were characterized by transmission electron microscopy (TEM), X-ray diffraction analysis (XRD), UV-vis diffuse-reflectance spectroscopy (DRS), BET surface area and elemental analysis. The photocatalytic properties of Pd-modified TiO2 particles were studied in a model reaction of phenol photodegradation under Vis irradiation, as well as active species involved in the photocatalytic reaction were determined. Microemulsion composition was found to be a crucial parameter in determining the features of the TiO2-based photocatalysts covered by metallic nanoparticles. The highest photocatalytic activity under Vis radiation was observed for the Pd-TiO2 sample (average diameter 2.4 nm) obtained using 0.1 mol% Pd in the ME system containing 1.5 wt% of water and 82.8 wt% of cyclohexane with average droplet size of 2.83 ± 0.18 nm. In this regard, synthesis of such metal-semiconductor composites through the microemulsion route should always be preceded by investigation of ME properties in order to the eliminate the inhibitory effect of ME internal structure.

Uniformly sized gold nanoparticles derived from PS-b-P2VP block copolymer templates for the controllable synthesis of Si nanowires.

PubMed

Lu, Jennifer Q; Yi, Sung Soo

2006-04-25

A monolayer of gold-containing surface micelles has been produced by spin-coating solution micelles formed by the self-assembly of the gold-modified polystyrene-b-poly(2-vinylpyridine) block copolymer in toluene. After oxygen plasma removed the block copolymer template, highly ordered and uniformly sized nanoparticles have been generated. Unlike other published methods that require reduction treatments to form gold nanoparticles in the zero-valent state, these as-synthesized nanoparticles are in form of metallic gold. These gold nanoparticles have been demonstrated to be an excellent catalyst system for growing small-diameter silicon nanowires. The uniformly sized gold nanoparticles have promoted the controllable synthesis of silicon nanowires with a narrow diameter distribution. Because of the ability to form a monolayer of surface micelles with a high degree of order, evenly distributed gold nanoparticles have been produced on a surface. As a result, uniformly distributed, high-density silicon nanowires have been generated. The process described herein is fully compatible with existing semiconductor processing techniques and can be readily integrated into device fabrication.

Selectivity of Glycine for Facets on Gold Nanoparticles.

PubMed

Shao, Qing; Hall, Carol K

2018-04-05

The performance of nanoparticles in medical applications depends on their interactions with various molecules. Despite extensive research on this subject, it remains unclear where on an inhomogeneous nanoparticle molecules prefer to adsorb. Here we investigate the selectivity of glycine molecules for facets on five bare gold nanoparticles with diameters from 1.0 to 5.0 nm. Well-tempered metadynamics simulations are conducted to calculate the adsorption free-energy landscapes of a glycine molecule on various locations for the five gold nanoparticles in explicit water. We also calculate the glycine molecule's adsorption free energies on the five gold nanoparticles in vacuum and on three flat gold surfaces as a reference. The simulation results show that glycine molecules prefer to adsorb on the (110) facet for the 1.0 and 2.0 nm nanoparticles, the edges for the 3.0 nm nanoparticle, and the (111) facet for the 4.0 and 5.0 nm nanoparticles in water. The effect of water solvent on the selectivity is investigated through comparing the adsorption free-energy landscapes for glycine molecules on the nanoparticles in water and in vacuum. The area of the facet plays a key role in determining the selectivity of glycine molecules for the different facets, especially the shift of the selectivity as the nanoparticle diameter changes. Our simulations suggest that nanoparticle size and shape can be engineered to control the preferred adsorption location of molecules.

[Health effects of nanoparticles and nanomaterials (II) methods for measurement of nanoparticles and their presence in the air].

PubMed

Fujitani, Yuji; Hirano, Seishiro

2008-05-01

The mass concentrations of airborne particles in the atmospheric, indoor, and industrial environments are regulated by air quality standards. Epidemiological studies show that there are significant positive correlations between particle mass concentrations and adverse health effects. In this context nanoparticles in the air, which are defined as particles with a diameter (Dp) of less than 50 nm or 100 nm for engineered ones, are gaining increasing attention despite a small contribution to the mass of total airborn particles. Contrary to the mass concentration the number concentrations of atmospheric nanoparticles are quite high in most cases. Moreover there is limited toxicological information on nanoparticles, although the deposition rate of nanoparticles in the respiratory region is known to be relatively high. Accordingly there are a lot of debates about what metric is best to depict the size distribution of nanoparticles, number, surface area, or mass. In this paper, we report methods for measurement of nanoparticles on the basis of those metrics. We also report sources of nanoparticle in the environment and occupational settings. The high number concentration of nanoparticles of 20-30 nm modal diameters have been documented at roadsides. Diesel-powered vehicles are major sources of those nanoparticles in the urban atmosphere. Engineered nanoparticles generate in some occupational settings in the handling processes such as bagging and cleaning with vacuum cleaners.

Template assisted synthesis and optical properties of gold nanoparticles.

NASA Astrophysics Data System (ADS)

Fodor, Petru; Lasalvia, Vincenzo

2009-03-01

A hybrid nanofabrication method (interference lithography + self assembly) was explored for the fabrication of arrays of gold nanoparticles. To ensure the uniformity of the nanoparticles, a template assisted synthesis was used in which the gold is electrodeposited in the pores of anodized aluminum membranes. The spacing between the pores and their ordering is controlled in the first fabrication step of the template in which laser lithography and metal deposition are used to produce aluminum films with controlled strain profiles. The diameter of the pores produced after anodizing the aluminum film in acidic solution determines the diameter of the gold particles, while their aspect ratio is controlled through the deposition time. Optical absorbance spectroscopy is used to evaluate the ability to tune the nanoparticles plasmon resonance spectra through control over their size and aspect ratio.

Impact of Particle Size and Polydispersity Index on the Clinical Applications of Lipidic Nanocarrier Systems.

PubMed

Danaei, M; Dehghankhold, M; Ataei, S; Hasanzadeh Davarani, F; Javanmard, R; Dokhani, A; Khorasani, S; Mozafari, M R

2018-05-18

Lipid-based drug delivery systems, or lipidic carriers, are being extensively employed to enhance the bioavailability of poorly-soluble drugs. They have the ability to incorporate both lipophilic and hydrophilic molecules and protecting them against degradation in vitro and in vivo. There is a number of physical attributes of lipid-based nanocarriers that determine their safety, stability, efficacy, as well as their in vitro and in vivo behaviour. These include average particle size/diameter and the polydispersity index (PDI), which is an indication of their quality with respect to the size distribution. The suitability of nanocarrier formulations for a particular route of drug administration depends on their average diameter, PDI and size stability, among other parameters. Controlling and validating these parameters are of key importance for the effective clinical applications of nanocarrier formulations. This review highlights the significance of size and PDI in the successful design, formulation and development of nanosystems for pharmaceutical, nutraceutical and other applications. Liposomes, nanoliposomes, vesicular phospholipid gels, solid lipid nanoparticles, transfersomes and tocosomes are presented as frequently-used lipidic drug carriers. The advantages and limitations of a range of available analytical techniques used to characterize lipidic nanocarrier formulations are also covered.

Large-scale synthesis of water-soluble luminescent hydroxyapatite nanorods for security printing.

PubMed

Chen, Xiaohu; Jin, Xiaoying; Tan, Junjun; Li, Wei; Chen, Minfang; Yao, Lan; Yang, Haitao

2016-04-15

Luminescent hydroxyapatite nanoparticles, which have excellent biocompatibility, excellent photostability, and strong fluorescence, have received increasing attention as bioprobes in cell imaging. However, they are also excellent candidates for use in ink-jet security printing. Successful products for related applications usually require highly crystalline, mono-dispersible hydroxyapatite nanorods with good colloidal stability and high fluorescence in aqueous media. These requirements are hard to simultaneously satisfy using most synthetic methods. In this paper, we report a simple and versatile hydrothermal method that incorporates the use of sodium citrate to prepare water-dispersible Eu(3+)-doped hydroxyapatite nanorods. The hydroxyapatite nanorods obtained using this method are highly crystalline rod-shaped particles with an average length of 50-80 nm and an average diameter of 15-30 nm. Dispersions of these hydroxyapatite nanorods, which are transparent with a slightly milky color under natural light and a bright red color when excited with 241 nm UV light, display zeta potentials of -35 mV and hydrodynamic diameters of 120 nm. These dispersions remain colloidally stable for a few months. Dispersions with these properties could be easily applied to security printing for confidential information storage and anti-counterfeiting technologies. Copyright © 2016 Elsevier Inc. All rights reserved.

Surface Modification and Damage of MeV-Energy Heavy Ion Irradiation on Gold Nanowires.

PubMed

Cheng, Yaxiong; Yao, Huijun; Duan, Jinglai; Xu, Lijun; Zhai, Pengfei; Lyu, Shuangbao; Chen, Yonghui; Maaz, Khan; Mo, Dan; Sun, Youmei; Liu, Jie

2017-05-15

Gold nanowires with diameters ranging from 20 to 90 nm were fabricated by the electrochemical deposition technique in etched ion track polycarbonate templates and were then irradiated by Xe and Kr ions with the energy in MeV range. The surface modification of nanowires was studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) characterizations. Different craters with and without protrusion on the gold nanowires were analyzed, and the two corresponding formation mechanisms, i.e., plastic flow and micro-explosion, were investigated. In addition, the sputtered gold nanoparticles caused by ion irradiation were studied and it was confirmed that the surface damage produced in gold nanowires was increased as the diameter of the nanowires decreased. It was also found that heavy ion irradiation can also create stacking fault tetrahedrons (SFTs) in gold nanowires and three different SFTs were confirmed in irradiated nanowires. A statistical analysis of the size distribution of SFTs in gold nanowires proved that the average size distribution of SFT was positively related to the nuclear stopping power of incident ions, i.e., the higher nuclear stopping power of incident ions could generate SFT with a larger average size in gold nanowires.

Surface Modification and Damage of MeV-Energy Heavy Ion Irradiation on Gold Nanowires

PubMed Central

Cheng, Yaxiong; Yao, Huijun; Duan, Jinglai; Xu, Lijun; Zhai, Pengfei; Lyu, Shuangbao; Chen, Yonghui; Maaz, Khan; Mo, Dan; Sun, Youmei; Liu, Jie

2017-01-01

Gold nanowires with diameters ranging from 20 to 90 nm were fabricated by the electrochemical deposition technique in etched ion track polycarbonate templates and were then irradiated by Xe and Kr ions with the energy in MeV range. The surface modification of nanowires was studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) characterizations. Different craters with and without protrusion on the gold nanowires were analyzed, and the two corresponding formation mechanisms, i.e., plastic flow and micro-explosion, were investigated. In addition, the sputtered gold nanoparticles caused by ion irradiation were studied and it was confirmed that the surface damage produced in gold nanowires was increased as the diameter of the nanowires decreased. It was also found that heavy ion irradiation can also create stacking fault tetrahedrons (SFTs) in gold nanowires and three different SFTs were confirmed in irradiated nanowires. A statistical analysis of the size distribution of SFTs in gold nanowires proved that the average size distribution of SFT was positively related to the nuclear stopping power of incident ions, i.e., the higher nuclear stopping power of incident ions could generate SFT with a larger average size in gold nanowires. PMID:28505116

Photoluminescence Analysis of White-Light-Emitting Si Nanoparticles Using Effective Mass Approximation Method

NASA Astrophysics Data System (ADS)

Lee, Soojin; Cho, Woon Jo; Kim, Yang Do; Kim, Eun Kyu; Park, Jae Gwan

2005-07-01

White-light-emitting Si nanoparticles were prepared from the sodium silicide (NaSi) precursor. The photoluminescence of colloidal Si nanoparticles has been fitted by effective mass approximation (EMA). We analyzed the correlation between experimental photoluminescence and simulated fitting curves. Both the mean diameter and the size dispersion of the white-light-emitting Si nanoparticles were estimated.

Inorganic fullerene-like nanoparticles of TiS 2

NASA Astrophysics Data System (ADS)

Margolin, Alexander; Popovitz-Biro, Ronit; Albu-Yaron, Ana; Rapoport, Lev; Tenne, Reshef

2005-08-01

Inorganic closed-cage nanoparticles of TiS 2 were synthesized using gas-phase synthesis. The reported nanoparticles are perfectly spherical with diameters centered between 60 and 80 nm, consisting from up to 80-100 concentric layers. The nucleation and growth mechanism was proposed for the formation of these nanoparticles. Tribological experiments emphasized the important role played by the spherical shape of the nanoparticles in providing rolling friction with a reduced friction coefficient and wear.

Microbes make average 2 nanometer diameter crystalline UO2 particles.

NASA Astrophysics Data System (ADS)

Suzuki, Y.; Kelly, S. D.; Kemner, K. M.; Banfield, J. F.

2001-12-01

It is well known that phylogenetically diverse groups of microorganisms are capable of catalyzing the reduction of highly soluble U(VI) to highly insoluble U(IV), which rapidly precipitates as uraninite (UO2). Because biological uraninite is highly insoluble, microbial uranyl reduction is being intensively studied as the basis for a cost-effective in-situ bioremediation strategy. Previous studies have described UO2 biomineralization products as amorphous or poorly crystalline. The objective of this study is to characterize the nanocrystalline uraninite in detail in order to determine the particle size, crystallinity, and size-related structural characteristics, and to examine the implications of these for reoxidation and transport. In this study, we obtained U-contaminated sediment and water from an inactive U mine and incubated them anaerobically with nutrients to stimulate reductive precipitation of UO2 by indigenous anaerobic bacteria, mainly Gram-positive spore-forming Desulfosporosinus and Clostridium spp. as revealed by RNA-based phylogenetic analysis. Desulfosporosinus sp. was isolated from the sediment and UO2 was precipitated by this isolate from a simple solution that contains only U and electron donors. We characterized UO2 formed in both of the experiments by high resolution-TEM (HRTEM) and X-ray absorption fine structure analysis (XAFS). The results from HRTEM showed that both the pure and the mixed cultures of microorganisms precipitated around 1.5 - 3 nm crystalline UO2 particles. Some particles as small as around 1 nm could be imaged. Rare particles around 10 nm in diameter were also present. Particles adhere to cells and form colloidal aggregates with low fractal dimension. In some cases, coarsening by oriented attachment on \\{111\\} is evident. Our preliminary results from XAFS for the incubated U-contaminated sample also indicated an average diameter of UO2 of 2 nm. In nanoparticles, the U-U distance obtained by XAFS was 0.373 nm, 0.012 nm smaller than found in the bulk structure of UO2 (0.385 nm). This indicates contraction within the nanoparticles due to tensile surface stress. Microbially formed UO2 is highly reactive, thus will be oxidized quickly as redox conditions change. Our findings support a growing number of studies that indicate that biominerals formed as the result of enzyme-mediated redox reactions are nanoparticulate. Preliminary results suggest that these particles will be readily transported through sandy aquifers, especially when conditions prevent high degrees of flocculation. Thus, despite its low (but size-dependent) solubility, UO2 nanoparticle transport may exert a fundamental control on mobility of U in contaminated environments.

Functionalizing large nanoparticles for small gaps in dimer nanoantennas

NASA Astrophysics Data System (ADS)

Vietz, Carolin; Lalkens, Birka; Acuna, Guillermo P.; Tinnefeld, Philip

2016-04-01

The process of functionalizing gold nanoparticles with DNA commonly competes with nanoparticle aggregation, especially for larger particles of more than 80 nm diameter. Longer DNA strands reduce the tendency for aggregation but commonly lead to larger gaps when applied in certain geometrical arrangements such as gap nanoantennas. Here, we demonstrate that reversing the polarization of one of the strands for hybridization (yielding a zipper-like geometry) is sterically possible with uncompromised yields. Using the single dye molecule’s fluorescence lifetime as an indicator of the proximity of the nanoparticle in combination with electrodynamic simulations, we determine the distance between the nanoparticle and the dye placed in a DNA origami pillar. Importantly, compared to the common shear geometry smaller distances between the connected structures are obtained which are independent of the length of the DNA connector. Using the zipper geometry, we then arranged nanoparticles of 100 and 150 nm diameter on DNA origami and formed gap nanoantennas. We find that the previously reported trend of increased fluorescence enhancement of ATTO647N with increasing particle size for 20-100 nm nanoparticles is stopped. Gap nanoantennas built with 150 nm nanoparticles exhibit smaller enhancement than those with 100 nm nanoparticles. These results are discussed with the aid of electrodynamic simulations.

Uncaria gambir Roxb. mediated green synthesis of silver nanoparticles using diethanolamine as capping agent

NASA Astrophysics Data System (ADS)

Labanni, A.; Zulhadjri; Handayani, D.; Arief, S.

2018-01-01

Studies of silver nanoparticles preparation has been developed increasingly due to the wide application in various areas and field, such as medicine, energy, catalysis, and electronic. An environmental-friendly method is needed to fabricate biocompatible silver nanoparticles without producing hazardous materials to the environment. In this study, we synthesized silver nanoparticles by green synthesis method, using leaf extract of gambir (Uncaria gambir Roxb.) as bioreducing agent and aqueous diethanolamine (DEA) solution as capping agents. The AgNO3/DEA molar ratio was varied to investigate the effect of DEA concentration to the properties of silver nanoparticles. The formation of silver nanoparticles was indicated by colour changes to yellowish brown and confirmed by result of UV-Vis spectrophotometer analysis which shown absorption band at 400 to 410 nm. The absorbance was increased to the reaction time of 24 hours, and was decrease by the increasing of DEA concentration in reaction. TEM analysis showed that prepared silver nanoparticles were spherical in shape with diameter of 3,5 - 45,5 nm. The diameter of DEA capped silver nanoparticles was 13 nm, smaller than uncapped silver nanoparticles which was 26 nm It exhibited good stability to time reaction of one month which was potential to be developed in some fields.

Visualization and quantification of magnetic nanoparticles into vesicular systems by combined atomic and magnetic force microscopy

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

Dong, C.; Department of Physics, SAPIENZA University of Rome, Piazzale A. Moro 5, 00185, Rome; Corsetti, S.

2015-06-23

We report a phenomenological approach for the quantification of the diameter of magnetic nanoparticles (MNPs) incorporated in non-ionic surfactant vesicles (niosomes) using magnetic force microscopy (MFM). After a simple specimen preparation, i.e., by putting a drop of solution containing MNPs-loaded niosomes on flat substrates, topography and MFM phase images are collected. To attempt the quantification of the diameter of entrapped MNPs, the method is calibrated on the sole MNPs deposited on the same substrates by analyzing the MFM signal as a function of the MNP diameter (at fixed tip-sample distance) and of the tip-sample distance (for selected MNPs). After calibration,more » the effective diameter of the MNPs entrapped in some niosomes is quantitatively deduced from MFM images.« less

Selectivity shifting behavior of Pd nanoparticles loaded zinc stannate/zinc oxide (Zn2SnO4/ZnO) nanowires sensors

NASA Astrophysics Data System (ADS)

Arafat, M. M.; Ong, J. Y.; Haseeb, A. S. M. A.

2018-03-01

In this research, the gas sensing behavior of Pd nanoparticles loaded zinc stannate/zinc oxide (Zn2SnO4/ZnO) nanowires were investigated. The Zn2SnO4/ZnO nanowires were grown on Au interdigitated alumina substrate by carbon assisted thermal evaporation process. Pd nanoparticles were loaded on the Zn2SnO4/ZnO nanowires by wet reduction process. The nanowires were characterized by X-ray diffractometer, field emission scanning electron microscope and energy dispersive X-ray spectroscope. The Zn2SnO4/ZnO and Pd nanoparticles loaded Zn2SnO4/ZnO nanowires were investigated for detecting H2, H2S and C2H5OH gases in N2 background. Results revealed that the average diameter and length of as-grown Zn2SnO4/ZnO nanowires were 74 nm and 30 μm, respectively. During wet reduction process,Pd particles having size of 20-60 nm were evenly distributed on the Zn2SnO4/ZnO nanowires. The Zn2SnO4/ZnO nanowires based sensors showed selective response towards C2H5OH whereas Pd nanoparticles loaded Zn2SnO4/ZnO nanowires showed selective response towards H2. The recovery time of the sensors reduced with Pd loading on Zn2SnO4/ZnO nanowires. A mechanism is proposed to elucidate the gas sensing mechanism of Pd nanoparticles loaded Zn2SnO4/ZnO nanowires.

Electron magnetic resonance and magnetooptical studies of nanoparticle-containing borate glasses

NASA Astrophysics Data System (ADS)

Kliava, Janis; Edelman, Irina; Ivanova, Oxana; Ivantsov, Ruslan; Petrakovskaja, Eleonora; Hennet, Louis; Thiaudière, Dominique; Saboungi, Marie-Louise

2011-03-01

We report electron magnetic resonance (EMR) and magnetooptical studies of borate glasses of molar composition 22.5K 2O-22.5Al 2O 3-55B 2O 3 co-doped with low concentrations of Fe 2O 3 and MnO. In as-prepared samples the paramagnetic ions, as a rule, are in diluted state. However, in the case where the ratio of the iron and manganese oxides in the charge is 3/2, magnetic nanoparticles with characteristics close to those of manganese ferrite are formed already at the first stage of the glass preparation, as evidenced by both magnetic circular dichroism (MCD) and EMR. After thermal treatment all glasses show characteristic MCD and EMR spectra, attesting to the presence of magnetic nanoparticles, predominantly including iron ions. Preliminary EXAFS measurements at the Fe K-absorption edge show an emergence of nanoparticles with a structure close to MnFe 2O 4 after annealing the glasses at 560 °C. By computer simulating the EMR spectra at variable temperatures, a superparamagnetic nature of relatively broad size and shape distribution with the average diameter of ca. 3-4 nm. The characteristic temperature-dependent shift of the apparent resonance field is explained by a strong temperature dependence of the magnetic anisotropy in the nanoparticles. The formation of magnetic nanoparticles confers to the potassium-alumina-borate glasses magnetic and magneto-optical properties typical of magnetically ordered substances. At the same time, they remain transparent in a part of the visible and near infrared spectral range and display a high Faraday rotation value.

Structural phase transitions in SrTiO 3 nanoparticles

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

Zhang, Han; Liu, Sizhan; Scofield, Megan E.

2017-07-31

Pressure dependent structural measurements on monodispersed nanoscale SrTiO3 samples with average diameters of 10 to ~80 nm were conducted to enhance the understanding of the structural phase diagram of nanoscale SrTiO3. A robust pressure independent polar structure was found in the 10 nm sample for pressures up to 13 GPa, while a size dependent cubic to tetragonal transition occurs (at P = Pc) for larger particle sizes. The results suggest that the growth of ~10 nm STO particles on substrates with significant lattice mismatch may maintain a polar state for a large range of strain values, possibly enabling device use.

Probing the atomic structure of metallic nanoclusters with the tip of a scanning tunneling microscope.

PubMed

Schouteden, Koen; Lauwaet, Koen; Janssens, Ewald; Barcaro, Giovanni; Fortunelli, Alessandro; Van Haesendonck, Chris; Lievens, Peter

2014-02-21

Preformed Co clusters with an average diameter of 2.5 nm are produced in the gas phase and are deposited under controlled ultra-high vacuum conditions onto a thin insulating NaCl film on Au(111). Relying on a combined experimental and theoretical investigation, we demonstrate visualization of the three-dimensional atomic structure of the Co clusters by high-resolution scanning tunneling microscopy (STM) using a Cl functionalized STM tip that can be obtained on the NaCl surface. More generally, use of a functionalized STM tip may allow for systematic atomic structure determination with STM of nanoparticles that are deposited on metal surfaces.

Carbothermal transformation of a graphitic carbon nanofiber/silica aerogel composite to a SiC/silica nanocomposite.

PubMed

Lu, Weijie; Steigerwalt, Eve S; Moore, Joshua T; Sullivan, Lisa M; Collins, W Eugene; Lukehart, C M

2004-09-01

Carbon nanofiber/silica aerogel composites are prepared by sol-gel processing of surface-enhanced herringbone graphitic carbon nanofibers (GCNF) and Si(OMe)4, followed by supercritical CO2 drying. Heating the resulting GCNF/silica aerogel composites to 1650 degrees C under a partial pressure of Ar gas initiates carbothermal reaction between the silica aerogel matrix and the carbon nanofiber component to form SiC/silica nanocomposites. The SiC phase is present as nearly spherical nanoparticles, having an average diameter of ca. 8 nm. Formation of SiC is confirmed by powder XRD and by Raman spectroscopy.

Exposure assessment of nano-sized and respirable particles at different workplaces

NASA Astrophysics Data System (ADS)

Tsai, Chuen-Jinn; Huang, Cheng-Yu; Chen, Sheng-Chieh; Ho, Chi-En; Huang, Cheng-Hsiung; Chen, Chun-Wan; Chang, Cheng-Ping; Tsai, Su-Jung; Ellenbecker, Michael J.

2011-09-01

In this study, nanoparticle (NP, diameter < 100 nm) and respirable particles measurements were conducted at three different nanopowder workplaces, including the mixing area of a nano-SiO2-epoxy molding compound plant (primary diameter: 15 nm), bagging areas of a nano-carbon black (nano-CB) (primary diameter: 32 nm) and a nano-CaCO3 (primary diameter: 94 nm) manufacturing plant. Chemical analysis of respirable particle mass (RPM) and NPs was performed to quantify the content of manufactured nanoparticles in the collected samples. Nanopowder products obtained from the plants were used in the laboratory dustiness testing using a rotating drum tester to obtain particle mass and number distributions. The obtained laboratory data were then used to elucidate the field data. Both field and laboratory data showed that NP number and mass concentrations of manufactured materials were close to the background level. Number concentration was elevated only for particles with the electrical mobility diameter >100 nm during bagging or feeding processes, unless there were combustion-related incidental sources existed. Large fraction of nanomaterials was found in the RPM due to agglomeration of nanomaterials or attachment of nanomaterials to the larger particles. From this study, it is concluded that RPM concentration measurements are necessary for the exposure assessment of nanoparticles in workplaces.

Simultaneous surface display and cargo loading of encapsulin nanocompartments and their use for rational vaccine design.

PubMed

Lagoutte, Priscillia; Mignon, Charlotte; Stadthagen, Gustavo; Potisopon, Supanee; Donnat, Stéphanie; Mast, Jan; Lugari, Adrien; Werle, Bettina

2018-05-11

In the past decades protein nanoparticles have successfully been used for vaccine applications. Their particulate nature and dense repetitive subunit organization makes them perfect carriers for antigen surface display and confers high immunogenicity. Nanoparticles have emerged as excellent candidates for vectorization of biological and immunostimulating molecules. Nanoparticles and biomolecular nanostructures such as ferritins or virus like particles have been used as diagnostic and therapeutic delivery systems, in vaccine development, as nanoreactors, etc. Recently, a new class of bacterial protein compartment has been discovered referred to as encapsulin nanocompartment. These compartments have been used for targeted diagnostics, as therapeutic delivery systems and as nanoreactors. Their biological origin makes them conveniently biocompatible and allows genetic functionalization. The aim of our study was to implement encapsulin nanocompartements for simultaneous epitope surface display and heterologous protein loading for rational vaccine design. For this proof-of-concept-study, we produced Thermotoga maritima encapsulin nanoparticles in E. coli. We demonstrated the ability of simultaneous display in our system by inserting Matrix protein 2 ectodomain (M2e) of influenza A virus at the nanoparticle surface and by packaging of a fluorescent reporter protein (GFP) into the internal cavity. Characterization of the nanoparticles by electronic microscopy confirmed homogenously shaped particles of 24 nm diameter in average. The results further show that engineering of the particle surface improved the loading capacity of the heterologous reporter protein suggesting that surface display may induce a critical elastic deformation resulting in improved stiffness. In Balb/c mice, nanoparticle immunization elicited antibody responses against both the surface epitope and the loaded cargo protein. These results confirm the potential of encapsulin nanocompartments for customized vaccine design and antigen delivery. Copyright © 2018 Elsevier Ltd. All rights reserved.

Design of eudragit RL nanoparticles by nanoemulsion method as carriers for ophthalmic drug delivery of ketotifen fumarate

PubMed Central

Soltani, Saieede; Zakeri-Milani, Parvin; Barzegar-Jalali, Mohammad; Jelvehgari, Mitra

2016-01-01

Objective(s): Ketotifen fumarate (KF) is a selective and noncompetitive histamine antagonist (H1-receptor) that is used topically in the treatment of allergic conditions of rhinitis and conjunctivitis. The aim of this study was to formulate and improve an ophthalmic delivery system of KF. Ocular nanoparticles were prepared with the objective of reducing the frequency of administration and obtaining controlled release to improve the anti-inflammatory drug delivery. Materials and Methods: In the present study, ocular KF loaded Eudragit RL 100 nanoparticles were prepared using O/W solvent diffusion method. The nanoparticles were evaluated for particle size, entrapment efficiency, surface morphology, X-ray diffraction (XRD), Fourier transform spectroscopy (FTIR), and differential scanning calorimetry (DSC). In vitro release and permeation studies were also carried out on nanoparticles. Results: An average size range of 182 to 314.30 nm in diameter was obtained and encapsulation efficiency up to 95.0% was observed for all the formulations. Drug release for all formulations after 24 hr was between 65.51% and 88.82% indicating effective controlled release property of KF. The mechanism of drug release for best formulation was found to be fickian diffusion mechanism. KF nanoparticles containing high polymer concentration (1:15) presented a faster drug release and a higher drug penetration; on the contrary, nanoparticles containing low polymer concentration (1:7.5) were able to give a more sustained release of the drug and thus a slower KF permeation through the cornea. Conclusion: The study revealed that KF NPs were capable of releasing the drug for a prolonged period of time and increasing the ocular bioavailability. PMID:27403262

Chitosan nanoparticles for targeting and sustaining minoxidil sulphate delivery to hair follicles.

PubMed

Matos, Breno Noronha; Reis, Thaiene Avila; Gratieri, Taís; Gelfuso, Guilherme Martins

2015-04-01

This work developed minoxidil sulphate-loaded chitosan nanoparticles (MXS-NP) for targeted delivery to hair follicles, which could sustain drug release and improve the topical treatment of alopecia. Chitosan nanoparticles were obtained using low-molecular weight chitosan and tripolyphosphate as crosslink agent. MXS-NP presented a monomodal distribution with hydrodynamic diameter of 235.5 ± 99.9 nm (PDI of 0.31 ± 0.01) and positive zeta potential (+38.6 ± 6.0 mV). SEM analysis confirmed nanoparticles average size and spherical shape. A drug loading efficiency of 73.0 ± 0.3% was obtained with polymer:drug ratio of 1:1 (w/w). Drug release through cellulose acetate membranes from MXS-NP was sustained in about 5 times in comparison to the diffusion rate of MXS from the solution (188.9 ± 6.0 μg/cm(2)/h and 35.4 ± 1.8 μg/cm(2)/h). Drug permeation studies through the skin in vitro, followed by selective recovery of MXS from the hair follicles, showed that MXS-NP application resulted in a two-fold MXS increase into hair follicles after 6h in comparison to the control solution (5.9 ± 0.6 μg/cm(2) and 2.9 ± 0.8 μg/cm(2)). MXS-loading in nanoparticles appears as a promising and easy strategy to target and sustain drug delivery to hair follicles, which may improve the topical treatment of alopecia. Copyright © 2015 Elsevier B.V. All rights reserved.

Synthesis of iron oxide nanoparticles in Listeria innocua Dps (DNA-binding protein from starved cells): a study with the wild-type protein and a catalytic centre mutant.

PubMed

Ceci, Pierpaolo; Chiancone, Emilia; Kasyutich, Oksana; Bellapadrona, Giuliano; Castelli, Lisa; Fittipaldi, Maria; Gatteschi, Dante; Innocenti, Claudia; Sangregorio, Claudio

2010-01-11

A comparative analysis of the magnetic properties of iron oxide nanoparticles grown in the cavity of the DNA-binding protein from starved cells of the bacterium Listeria innocua, LiDps, and of its triple-mutant lacking the catalytic ferroxidase centre, LiDps-tm, is presented. TEM images and static and dynamic magnetic and electron magnetic resonance (EMR) measurements reveal that, under the applied preparation conditions, namely alkaline pH, high temperature (65 degrees C), exclusion of oxygen, and the presence of hydrogen peroxide, maghemite and/or magnetite nanoparticles with an average diameter of about 3 nm are mineralised inside the cavities of both LiDps and LiDps-tm. The magnetic nanoparticles (MNPs) thus formed show similar magnetic properties, with superparamagnetic behaviour above 4.5 K and a large magnetic anisotropy. Interestingly, in the EMR spectra an absorption at half-field is observed, which can be considered as a manifestation of the quantum behaviour of the MNPs. These results indicate that Dps proteins can be advantageously used for the production of nanomagnets at the interface between molecular clusters and traditional MNPs and that the presence of the ferroxidase centre, though increasing the efficiency of nanoparticle formation, does not affect the nature and fine structure of the MNPs. Importantly, the self-organisation of MNP-containing Dps on HRTEM grids suggests that Dps-enclosed MNPs can be deposited on surfaces in an ordered fashion.

Green synthesis of gold nanoparticles using chlorogenic acid and their enhanced performance for inflammation.

PubMed

Hwang, Su Jung; Jun, Sang Hui; Park, Yohan; Cha, Song-Hyun; Yoon, Minho; Cho, Seonho; Lee, Hyo-Jong; Park, Youmie

2015-10-01

Here we developed a novel green synthesis method for gold nanoparticles (CGA-AuNPs) using chlorogenic acid (CGA) as reductants without the use of other chemicals and validated the anti-inflammatory efficacy of CGA-AuNPs in vitro and in vivo. The resulting CGA-AuNPs appeared predominantly spherical in shape with an average diameter of 22.25±4.78nm. The crystalline nature of the CGA-AuNPs was confirmed by high-resolution X-ray diffraction and by selected-area electron diffraction analyses. High-resolution liquid chromatography/electrospray ionization mass spectrometry revealed that the caffeic acid moiety of CGA forms quinone structure through a two-electron oxidation causing the reduction of Au(3+) to Au(0). When compared to CGA, CGA-AuNPs exhibited enhanced anti-inflammatory effects on NF-κB-mediated inflammatory network, as well as cell adhesion. Collectively, green synthesis of CGA-AuNPs using bioactive reductants and mechanistic studies based on mass spectrometry may open up new directions in nanomedicine and CGA-AuNPs can be an anti-inflammatory nanomedicine for future applications. Gold nanoparticles (Au NPs) have been shown to be very useful in many applications due to their easy functionalization capability. In this article, the authors demonstrated a novel method for the synthesis of gold nanoparticles using chlorogenic acid (CGA) as reductants. In-vitro experiments also confirmed biological activity of the resultant gold nanoparticles. Further in-vivo studies are awaited. Copyright © 2015 Elsevier Inc. All rights reserved.

NIR-labeled perfluoropolyether nanoemulsions for drug delivery and imaging

PubMed Central

O’Hanlon, Claire E.; Amede, Konjit G.; O’Hear, Meredith R.; Janjic, Jelena M.

2012-01-01

Theranostic nanoparticle development recently took center stage in the field of drug delivery nanoreagent design. Theranostic nanoparticles combine therapeutic delivery systems (liposomes, micelles, nanoemulsions, etc.) with imaging reagents (MRI, optical, PET, CT). This combination allows for non-invasive in vivo monitoring of therapeutic nanoparticles in diseased organs and tissues. Here, we report a novel perfluoropolyether (PFPE) nanoemulsion with a water-insoluble lipophilic drug. The formulation enables non-invasive monitoring of nanoemulsion biodistribution using two imaging modalities, 19F MRI and near-infrared (NIR) optical imaging. The nanoemulsion is composed of PFPE-tyramide as a 19F MRI tracer, hydrocarbon oil, surfactants, and a NIR dye. Preparation utilizes a combination of self-assembly and high energy emulsification methods, resulting in droplets with average diameter 180 nm and low polydispersity index (PDI less than 0.2). A model nonsteroidal anti-inflammatory drug (NSAID), celecoxib, was incorporated into the formulation at 0.2 mg/mL. The reported nanoemulsion’s properties, including small particle size, visibility under 19F NMR and NIR fluorescence spectroscopy, and the ability to carry drugs make it an attractive potential theranostic agent for cancer imaging and treatment. PMID:22675234

Fabrication of water-repellent cellulose fiber coated with magnetic nanoparticles under supercritical carbon dioxide

NASA Astrophysics Data System (ADS)

Xu, Shengjie; Shen, Danping; Wu, Peiyi

2013-04-01

Hematite nanoparticle-coated magnetic composite fiber was prepared in supercritical carbon dioxide (scCO2). With the help of scCO2, cellulose did not need to be dissolved and regenerated and it could be in any form (e.g., cotton wool, filter paper, textile, etc.). The penetrating and swelling effect of scCO2, the slowing reaction rate of weak alkalis, and the template effect of cellulose fibers were discovered to be the key factors for the fabrication of ordered cellulose/Fe2O3 composite fibers. The structures of the composite fibers as well as the layers of Fe2O3 particles were characterized by means of scanning/transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and Raman investigation. It was found that α-Fe2O3 granules which ranged from 30 to 85 nm with average diameter around 55 nm would be generated on the surface of cellulose fibers via potassium acetate, while irregular square prisms (ranged from 200 to 600 nm) which were composed of smaller nanoparticles ( 10 nm) would be fabricated via urea. And, the obtained composite was highly water repellent with superparamagnetic or ferromagnetic properties.

Catalytic applications of bio-inspired nanomaterials

NASA Astrophysics Data System (ADS)

Pacardo, Dennis Kien Balaong

The biomimetic synthesis of Pd nanoparticles was presented using the Pd4 peptide, TSNAVHPTLRHL, isolated from combinatorial phage display library. Using this approach, nearly monodisperse and spherical Pd nanoparticles were generated with an average diameter of 1.9 +/- 0.4 nm. The peptide-based nanocatalyst were employed in the Stille coupling reaction under energy-efficient and environmentally friendly reaction conditions of aqueous solvent, room temperature and very low catalyst loading. To this end, the Pd nanocatalyst generated high turnover frequency (TOF) value and quantitative yields using ≥ 0.005 mol% Pd as well as catalytic activities with different aryl halides containing electron-withdrawing and electron-donating groups. The Pd4-capped Pd nanoparticles followed the atom-leaching mechanism and were found to be selective with respect to substrate identity. On the other hand, the naturally-occurring R5 peptide (SSKKSGSYSGSKGSKRRIL) was employed in the synthesis of biotemplated Pd nanomaterials which showed morphological changes as a function of Pd:peptide ratio. TOF analysis for hydrogenation of olefinic alcohols showed similar catalytic activity regardless of nanomorphology. Determination of catalytic properties of these bio-inspired nanomaterials are important as they serve as model system for alternative green catalyst with applications in industrially important transformations.

Biomass-based magnetic fluorescent nanoparticles: One-step scalable synthesis, application as drug carriers and mechanism study.

PubMed

Li, Lei; Wang, Feijun; Shao, Ziqiang

2018-03-15

A biomass-based magnetic fluorescent nanoparticle (MFNPs) was successively in situ synthesized via a one-step high-gravity approach, which constructed by a magnetic core of Fe 3 O 4 nanoparticles, the fluorescent marker of carbon dots (CDs), and shells of chitosan (CS). The obtained MFNPs had a 10 nm average diameter and narrow particle size distribution, low cytotoxicity, superior fluorescent emission and superparamagnetic properties. The encapsulating and release 5-fluorouracil experiments confirmed that the introduction of CS/CDs effectively improved the drug loading capacity. Mechanism and kinetic studies proved that: (i) the monolayer adsorption was the main sorption mode under the studied conditions; (ii) the whole adsorption process was controlled by intra-liquid diffusion mass transfer and governed by chemisorption; and (iii) the release process was controlled by Fickian diffusion. These results demonstrated this method to one-step continuously produce MFNPs and the construction of non-toxic nanostructure possessed great superiority in currently Nano-delivery systems, which would show high application value in targeted drug delivery, magnetic fluid hyperthermia treatment, magnetic resonance imaging (MRI), in vitro testing and relative research. Copyright © 2017 Elsevier Ltd. All rights reserved.

A high-coverage nanoparticle monolayer for the fabrication of a subwavelength structure on InP substrates.

PubMed

Kim, Dae-Seon; Park, Min-Su; Jang, Jae-Hyung

2011-08-01

Subwavelength structures (SWSs) were fabricated on the Indium Phosphide (InP) substrate by utilizing the confined convective self-assembly (CCSA) method followed by reactive ion etching (RIE). The surface condition of the InP substrate was changed by depositing a 30-nm-thick SiO2 layer and subsequently treating the surface with O2 plasma to achieve better surface coverage. The surface coverage of nanoparticle monolayer reached 90% by using O2 plasma-treated SiO2/InP substrate among three kinds of starting substrates such as the bare InP, SiO2/InP and O2 plasma-treated SiO2/InP substrate. A nanoparticle monolayer consisting of polystyrene spheres with diameter of 300 nm was used as an etch mask for transferring a two-dimensional periodic pattern onto the InP substrate. The fabricated conical SWS with an aspect ratio of 1.25 on the O2 plasma-treated SiO2/InP substrate exhibited the lowest reflectance. The average reflectance of the conical SWS was 5.84% in a spectral range between 200 and 900 nm under the normal incident angle.

Blood-pool contrast agent for pre-clinical computed tomography

NASA Astrophysics Data System (ADS)

Cruje, Charmainne; Tse, Justin J.; Holdsworth, David W.; Gillies, Elizabeth R.; Drangova, Maria

2017-03-01

Advances in nanotechnology have led to the development of blood-pool contrast agents for micro-computed tomography (micro-CT). Although long-circulating nanoparticle-based agents exist for micro-CT, they are predominantly based on iodine, which has a low atomic number. Micro-CT contrast increases when using elements with higher atomic numbers (i.e. lanthanides), particularly at higher energies. The purpose of our work was to develop and evaluate a lanthanide-based blood-pool contrast agent that is suitable for in vivo micro-CT. We synthesized a contrast agent in the form of polymer-encapsulated Gd nanoparticles and evaluated its stability in vitro. The synthesized nanoparticles were shown to have an average diameter of 127 +/- 6 nm, with good size dispersity. Particle size distribution - evaluated by dynamic light scattering over the period of two days - demonstrated no change in size of the contrast agent in water and saline. Additionally, our contrast agent was stable in a mouse serum mimic for up to 30 minutes. CT images of the synthesized contrast agent (containing 27 mg/mL of Gd) demonstrated an attenuation of over 1000 Hounsfield Units. This approach to synthesizing a Gd-based blood-pool contrast agent promises to enhance the capabilities of micro-CT imaging.

Arrays of size and distance controlled platinum nanoparticles fabricated by a colloidal method

NASA Astrophysics Data System (ADS)

Manzke, Achim; Vogel, Nicolas; Weiss, Clemens K.; Ziener, Ulrich; Plettl, Alfred; Landfester, Katharina; Ziemann, Paul

2011-06-01

Based on emulsion polymerization in the presence of a Pt complex, polystyrene (PS) particles were prepared exhibiting a well defined average diameter with narrow size-distribution. Furthermore, the colloids contain a controlled concentration of the Pt precursor complex. Optimized coating of Si substrates with such colloids leads to extended areas of hexagonally ordered close-packed PS particles. Subsequent application of plasma etching and annealing steps allows complete removal of the PS carriers and in parallel nucleation and growth of Pt nanoparticles (NPs) which are located at the original center of the PS colloids. In this way, hexagonally arranged spherical Pt NPs are obtained with controlled size and interparticle distances demonstrating variability and precision with so far unknown parameter scalability. This control is demonstrated by the fabrication of Pt NP arrays at a fixed particle distance of 185 nm while systematically varying the diameters between 8 and 15 nm. Further progress could be achieved by seeded emulsion polymerization. Here, Pt loaded PS colloids of 130 nm were used as seeds for a subsequent additional emulsion polymerization, systematically enlarging the diameter of the PS particles. Applying the plasma and annealing steps as above, in this way hexagonally ordered arrays of 9 nm Pt NPs could be obtained at distances up to 260 nm. To demonstrate their stability, such Pt particles were used as etching masks during reactive ion etching thereby transferring their hexagonal pattern into the Si substrate resulting in corresponding arrays of nanopillars.Based on emulsion polymerization in the presence of a Pt complex, polystyrene (PS) particles were prepared exhibiting a well defined average diameter with narrow size-distribution. Furthermore, the colloids contain a controlled concentration of the Pt precursor complex. Optimized coating of Si substrates with such colloids leads to extended areas of hexagonally ordered close-packed PS particles. Subsequent application of plasma etching and annealing steps allows complete removal of the PS carriers and in parallel nucleation and growth of Pt nanoparticles (NPs) which are located at the original center of the PS colloids. In this way, hexagonally arranged spherical Pt NPs are obtained with controlled size and interparticle distances demonstrating variability and precision with so far unknown parameter scalability. This control is demonstrated by the fabrication of Pt NP arrays at a fixed particle distance of 185 nm while systematically varying the diameters between 8 and 15 nm. Further progress could be achieved by seeded emulsion polymerization. Here, Pt loaded PS colloids of 130 nm were used as seeds for a subsequent additional emulsion polymerization, systematically enlarging the diameter of the PS particles. Applying the plasma and annealing steps as above, in this way hexagonally ordered arrays of 9 nm Pt NPs could be obtained at distances up to 260 nm. To demonstrate their stability, such Pt particles were used as etching masks during reactive ion etching thereby transferring their hexagonal pattern into the Si substrate resulting in corresponding arrays of nanopillars. Electronic supplementary information (ESI) available: Detailed description of the experimental part (S1-S4) platinum concentration inside the polymer particles synthesized by a seeded polymerization from the same seed particles measured by ICP-OES (Fig. S1 and S5); SEM image of Pt complex containing PS particles after oxygen plasma treatment (Fig. S2 and S6); effect of hydrofluoric acid treatment on silicon oxide elevation under Pt NPs (Fig. S3 and S6); SEM images demonstrating the variability of Pt NP distance while keeping the diameter constant (Fig. S4 and S8); results of experimental determination of Pt content by ICP-OES (Tables S1 and S9); diameter of the particles at different fabrication states (Tables S2 and S10). See DOI: 10.1039/c1nr10169b

Silver metal nanoparticles study for biomedical and green house applications

NASA Astrophysics Data System (ADS)

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

2017-02-01

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

Particokinetics: computational analysis of the superparamagnetic iron oxide nanoparticles deposition process

PubMed Central

Cárdenas, Walter HZ; Mamani, Javier B; Sibov, Tatiana T; Caous, Cristofer A; Amaro, Edson; Gamarra, Lionel F

2012-01-01

Background Nanoparticles in suspension are often utilized for intracellular labeling and evaluation of toxicity in experiments conducted in vitro. The purpose of this study was to undertake a computational modeling analysis of the deposition kinetics of a magnetite nanoparticle agglomerate in cell culture medium. Methods Finite difference methods and the Crank–Nicolson algorithm were used to solve the equation of mass transport in order to analyze concentration profiles and dose deposition. Theoretical data were confirmed by experimental magnetic resonance imaging. Results Different behavior in the dose fraction deposited was found for magnetic nanoparticles up to 50 nm in diameter when compared with magnetic nanoparticles of a larger diameter. Small changes in the dispersion factor cause variations of up to 22% in the dose deposited. The experimental data confirmed the theoretical results. Conclusion These findings are important in planning for nanomaterial absorption, because they provide valuable information for efficient intracellular labeling and control toxicity. This model enables determination of the in vitro transport behavior of specific magnetic nanoparticles, which is also relevant to other models that use cellular components and particle absorption processes. PMID:22745539

Tunable UV- and Visible-Light Photoresponse Based on p-ZnO Nanostructures/n-ZnO/Glass Peppered with Au Nanoparticles.

PubMed

Hsu, Cheng-Liang; Lin, Yu-Hong; Wang, Liang-Kai; Hsueh, Ting-Jen; Chang, Sheng-Po; Chang, Shoou-Jinn

2017-05-03

UV- and visible-light photoresponse was achieved via p-type K-doped ZnO nanowires and nanosheets that were hydrothermally synthesized on an n-ZnO/glass substrate and peppered with Au nanoparticles. The K content of the p-ZnO nanostructures was 0.36 atom %. The UV- and visible-light photoresponse of the p-ZnO nanostructures/n-ZnO sample was roughly 2 times higher than that of the ZnO nanowires. The Au nanoparticles of various densities and diameter sizes were deposited on the p-ZnO nanostructures/n-ZnO samples by a simple UV photochemical reaction method yielding a tunable and enhanced UV- and visible-light photoresponse. The maximum UV and visible photoresponse of the Au nanoparticle sample was obtained when the diameter size of the Au nanoparticle was approximately 5-35 nm. On the basis of the localized surface plasmon resonance effect, the UV, blue, and green photocurrent/dark current ratios of Au nanoparticle/p-ZnO nanostructures/n-ZnO are ∼1165, ∼94.6, and ∼9.7, respectively.

Nanowire-Intensified Metal-Enhanced Fluorescence in Hybrid Polymer-Plasmonic Electrospun Filaments.

PubMed

Camposeo, Andrea; Jurga, Radoslaw; Moffa, Maria; Portone, Alberto; Cardarelli, Francesco; Della Sala, Fabio; Ciracì, Cristian; Pisignano, Dario

2018-05-01

Hybrid polymer-plasmonic nanostructures might combine high enhancement of localized fields from metal nanoparticles with light confinement and long-range transport in subwavelength dielectric structures. Here, the complex behavior of fluorophores coupling to Au nanoparticles within polymer nanowires, which features localized metal-enhanced fluorescence (MEF) with unique characteristics compared to conventional structures, is reported. The intensification effect when the particle is placed in the organic filaments is remarkably higher with respect to thin films of comparable thickness, thus highlighting a specific, nanowire-related enhancement of MEF effects. A dependence on the confinement volume in the dielectric nanowire is also indicated, with MEF significantly increasing upon reduction of the wire diameter. These findings are rationalized by finite element simulations, predicting a position-dependent enhancement of the quantum yield of fluorophores embedded in the fibers. Calculation of the ensemble-averaged fluorescence enhancement unveils the possibility of strongly enhancing the overall emission intensity for structures with size twice the diameter of the embedded metal particles. These new, hybrid fluorescent systems with localized enhanced emission, and the general nanowire-enhanced MEF effects associated to them, are highly relevant for developing nanoscale light-emitting devices with high efficiency and intercoupled through nanofiber networks, highly sensitive optical sensors, and novel laser architectures. © 2018 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA Weinheim.

Designed synthesis and stacking architecture of solid and mesoporous TiO(2) nanoparticles for enhancing the light-harvesting efficiency of dye-sensitized solar cells.

PubMed

Ahn, Ji Young; Moon, Kook Joo; Kim, Ji Hoon; Lee, Sang Hyun; Kang, Jae Wook; Lee, Hyung Woo; Kim, Soo Hyung

2014-01-22

We fabricated solid and mesoporous TiO2 nanoparticles (NPs) with relatively large primary sizes of approximately 200 nm via inorganic templates for aero-sol-gel and subsequent aqueous-washing processes. The amount of dye molecules adsorbed by the internal pores in the mesoporous TiO2 NPs was increased by creating the nanopores within the solid TiO2 NPs. Simultaneously, the light-scattering effect of the mesoporous TiO2 NPs fabricated by this approach was secured by maintaining their spherical shape and relatively large average size. By precisely accumulating the fabricated solid or mesoporous 200 nm diameter TiO2 NPs on top of a conventional 25 nm diameter TiO2 NP-based underlayer, we could systematically examine the effect of the solid and mesoporous TiO2 NPs on the photovoltaic performance of dye-sensitized solar cells (DSSCs). Consequently, the stacking architecture of the mesoporous TiO2 NP-based overlayer, which functioned as both a light-scattering and dye-supporting medium, on top of a conventional solid TiO2 NP-based underlayer in a DSSC photoelectrode (i.e., double-layer structures) was found to be very promising for significantly improving the photovoltaic properties of conventional solid TiO2 NP single-layer-based DSSCs.

Enhancement in visible light photocatalytic activity by embedding Cu nanoparticles over CuS/MCM-41 nanocomposite

NASA Astrophysics Data System (ADS)

Sohrabnezhad, Sh.; Karamzadeh, M.

2017-07-01

This article indicate the biogenic synthesis of copper nanoparticles (Cu NPs) using the borage flowers extract of Borago officinalis over CuS/MCM-41 nanocomposite (NC). No external reducing was utilized in the developed method. The CuS-MCM-41 NC was used as stabilizing agent. The synthesis of CuS nanostructure in MCM-41 material has been realized by hydrothermal method. Their physiochemical properties have been characterized by X-ray diffraction, transmission electron microscopy (TEM), UV-Visible diffuse reflectance spectroscopy, and Fourier transform infrared spectroscopy. On the basis of TEM images, a layer of Cu NPs has been located over CuS/MCM-41 NC with average diameter of 60-80 nm. The results revealed the spherical nature of the prepared Cu NPs with diameter less than 10 nm. The DR spectra of Cu NPs in MCM-41 and CuS-MCM-41 NCs showed surface plasmon resonance bands at 570 and 500-600 nm, respectively. The photocatalytic activity was evaluated under visible light irradiation using the photocatalytic degradation of methylene blue (MB) as a model reaction. The prepared Cu/CuS/MCM-41 nanocomposite microspheres showed higher photodegradation ability for MB than CuS/MCM-41. The degradation of MB achieved up to 80% after 60 min and the nanocomposite could be recycled and reused.

Antibacterial electrospun chitosan-polyethylene oxide nanocomposite mats containing ZIF-8 nanoparticles.

PubMed

Kohsari, Iraj; Shariatinia, Zahra; Pourmortazavi, Seied Mahdi

2016-10-01

Antimicrobial chitosan-polyethylene oxide (CS-PEO) nanofiber mats loaded with 3, 5 and 10% (w/w) of zeolitic imidazolate framework-8 nanoparticles (ZIF-8 NPs, ∼60nm diameter) were developed by electrospinning technique. The CS-PEO-GA-3% ZIF-8 NPs crosslinked with glutaraldehyde (GA) vapor was also prepared. The electrospun mats were characterized by various analysis including FE-SEM, EDAX, elemental mapping, FT-IR, contact angle, TGA/DSC as well as tensile strength analysis. The nanofibers had average diameters within the range ∼70-120nm. Antimicrobial activities of the CS-PEO and CS-PEO-3% ZIF-8 mats were evaluated by the viable cell-counting method for determining their effectiveness in reducing or halting the growth of Staphylococcus aureus and Escherichia coli bacteria so that the CS-PEO mat containing 3% ZIF-8 revealed 100% bactericidal activity against both kinds of bacteria. The crosslinked CS-PEO-GA-3% ZIF-8 NPs sample was less thermally stable but more hydrophilic than its related non-crosslinked mat reflecting there was no need to crosslink the fibers using a chemical crosslinker having adverse effects. The highest hydrophobicity and appropriate thermal and tensile properties of CS-PEO-3% ZIF-8 NPs among those of the mats including 5 and 10% ZIF-8 NPs suggested that the mentioned mat is the most suitable sample for food coating applications. Copyright © 2016 Elsevier B.V. All rights reserved.

Green synthesis of Ag nanoparticles for water treatment (antimicrobial on Eschirichia coli)

NASA Astrophysics Data System (ADS)

Darus, Mazlina Mat; Mahusin, Wan Norazwani

2017-05-01

Green synthesis approach was used to synthesis silver (Ag) nanoparticles. In this study, a one-step method was employed via hydrothermal technique. Samples are synthesized at different temperatures and times. All samples were characterized by Field Emission Scanning Electron Microscopy (FESEM). The morphology of the as-synthesized Ag samples are consists of nanoparticles and nanoplates with the diameter is in the range of 45 - 140 nm. The Ag nanoparticles were tested on Gram-Negative bacteria, Eschirichia coli (E.coli) which represent as an indicator for water pollution by using disc diffusion methods. Different concentrations of Ag nanoparticles were used to treat E.coli which is at 25 µg/ml, 50 µg/ml and 100 µg/ml respectively. The results show that for every samples, the inhibition zone of the E.coli increased as the concentration of Ag nanoparticles increased. Ag nanoparticles which synthesized at 100 °C/ 8 hrs exhibits the most optimum inhibition zone for the growth of E.coli due to its smaller size and the triangular nanoplate shaped. The diameter of the inhibition zone is between 6.17 ± 0.03 to 8.03 ± 0.03 mm.

Green Route for Silver Nanoparticles Synthesis by Raphanus Sativus Extract in a Continuous Flow Tubular Microreactor

NASA Astrophysics Data System (ADS)

Jolhe, P. D.; Bhanvase, B. A.; Patil, V. S.; Sonawane, S. H.

The present work deals with the investigation of the greener route for the production of silver nanoparticles using Raphanus sativus (R. sativus) bioextract in a continuous flow tubular microreactor. The parameters affecting the particle size and distribution were investigated. From the results obtained it can be inferred that the ascorbic acid (reducing agent) present in the R. sativus bioextract is responsible for the reduction of silver ions. At optimum condition, the particle size distribution of nanoparticles is found between 18nm and 39nm. The absorbance value was found to be decreased with an increase in the diameter of the microreactor. It indicates that a number of nuclei are formed in the micrometer sized (diameter) reactor because of the better solute transfer rate leading to the formation of large number of silver nanoparticles. The study of antibacterial activity of green synthesized silver nanoparticles shows effective inhibitory activity against waterborne pathogens, Shegella and Listeria bacteria.

Diffusive dynamics of nanoparticles in ultra-confined media

DOE PAGES

Jacob, Jack Deodato; Conrad, Jacinta; Krishnamoorti, Ramanan; ...

2015-08-10

Differential dynamic microscopy (DDM) was used to investigate the diffusive dynamics of nanoparticles of diameter 200 400 nm that were strongly confined in a periodic square array of cylindrical nanoposts. The minimum distance between posts was 1.3 5 times the diameter of the nanoparticles. The image structure functions obtained from the DDM analysis were isotropic and could be fit by a stretched exponential function. The relaxation time scaled diffusively across the range of wave vectors studied, and the corresponding scalar diffusivities decreased monotonically with increased confinement. The decrease in diffusivity could be described by models for hindered diffusion that accountedmore » for steric restrictions and hydrodynamic interactions. The stretching exponent decreased linearly as the nanoparticles were increasingly confined by the posts. Altogether, these results are consistent with a picture in which strongly confined nanoparticles experience a heterogeneous spatial environment arising from hydrodynamics and volume exclusion on time scales comparable to cage escape, leading to multiple relaxation processes and Fickian but non-Gaussian diffusive dynamics.« less

Size Control of Porous Silicon-Based Nanoparticles via Pore-Wall Thinning.

PubMed

Secret, Emilie; Leonard, Camille; Kelly, Stefan J; Uhl, Amanda; Cozzan, Clayton; Andrew, Jennifer S

2016-02-02

Photoluminescent silicon nanocrystals are very attractive for biomedical and electronic applications. Here a new process is presented to synthesize photoluminescent silicon nanocrystals with diameters smaller than 6 nm from a porous silicon template. These nanoparticles are formed using a pore-wall thinning approach, where the as-etched porous silicon layer is partially oxidized to silica, which is dissolved by a hydrofluoric acid solution, decreasing the pore-wall thickness. This decrease in pore-wall thickness leads to a corresponding decrease in the size of the nanocrystals that make up the pore walls, resulting in the formation of smaller nanoparticles during sonication of the porous silicon. Particle diameters were measured using dynamic light scattering, and these values were compared with the nanocrystallite size within the pore wall as determined from X-ray diffraction. Additionally, an increase in the quantum confinement effect is observed for these particles through an increase in the photoluminescence intensity of the nanoparticles compared with the as-etched nanoparticles, without the need for a further activation step by oxidation after synthesis.

Ultrasonic-assisted chemical reduction synthesis and structural characterization of copper nanoparticles

NASA Astrophysics Data System (ADS)

Anh-Nga, Nguyen T.; Tuan-Anh, Nguyen; Thanh-Quoc, Nguyen; Ha, Do Tuong

2018-04-01

Copper nanoparticles, due to their special properties, small dimensions and low-cost preparation, have many potential applications such as in optical, electronics, catalysis, sensors, antibacterial agents. In this study, copper nanoparticles were synthesized by chemical reduction method with different conditions in order to investigate the optimum conditions which gave the smallest (particle diameter) dimensions. The synthesis step used copper (II) acetate salt as precursor, ascorbic acid as reducing agent, glycerin and polyvinylpyrrolidone (PVP) as protector and stabilizer. The assistance of ultrasonic was were considered as the significant factor affecting the size of the synthesized particles. The results showed that the copper nanoparticles have been successfully synthesized with the diameter as small as 20-40 nm and the conditions of ultrasonic waves were 48 kHz of frequency, 20 minutes of treated time and 65-70 °C of temperature. The synthesized copper nanoparticles were characterized by optical absorption spectrum, scanning electron microscopy (SEM), and Fourier Transform Infrared Spectrometry.

Surface spins disorder in uncoated and SiO2 coated maghemite nanoparticles

NASA Astrophysics Data System (ADS)

Zeb, F.; Nadeem, K.; Shah, S. Kamran Ali; Kamran, M.; Gul, I. Hussain; Ali, L.

2017-05-01

We studied the surface spins disorder in uncoated and silica (SiO2) coated maghemite (γ-Fe2O3) nanoparticles using temperature and time dependent magnetization. The average crystallite size for SiO2 coated and uncoated nanoparticles was about 12 and 29 nm, respectively. Scanning electron microscopy (SEM) showed that the nanoparticles are spherical in shape and well separated. Temperature scans of zero field cooled (ZFC)/field cooled (FC) magnetization measurements showed lower average blocking temperature (TB) for SiO2 coated maghemite nanoparticles as compared to uncoated nanoparticles. The saturation magnetization (Ms) of SiO2 coated maghemite nanoparticles was also lower than the uncoated nanoparticles and is attributed to smaller average crystallite size of SiO2 coated nanoparticles. For saturation magnetization vs. temperature data, Bloch's law (M(T)= M(0).(1- BTb)) was fitted well for both uncoated and SiO2 coated nanoparticles and yields: B =3×10-7 K-b, b=2.22 and B=0.0127 K-b, b=0.57 for uncoated and SiO2 coated nanoparticles, respectively. Higher value of B for SiO2 coated nanoparticles depicts decrease in exchange coupling due to enhanced surface spins disorder (broken surface bonds) as compared to uncoated nanoparticles. The Bloch's exponent b was decreased for SiO2 coated nanoparticles which is due to their smaller average crystallite size or finite size effects. Furthermore, a sharp increase of coercivity at low temperatures (<25 K) was observed for SiO2 coated nanoparticles which is also due to contribution of increased surface anisotropy or frozen surface spins in these smaller nanoparticles. The FC magnetic relaxation data was fitted to stretched exponential law which revealed slower magnetic relaxation for SiO2 coated nanoparticles. All these measurements revealed smaller average crystallite size and enhanced surface spins disorder in SiO2 coated nanoparticles than in uncoated γ-Fe2O3 nanoparticles.

Preparation and characterization of 6-mercaptopurine-coated magnetite nanoparticles as a drug delivery system.

PubMed

Dorniani, Dena; Hussein, Mohd Zobir Bin; Kura, Aminu Umar; Fakurazi, Sharida; Shaari, Abdul Halim; Ahmad, Zalinah

2013-01-01

Iron oxide nanoparticles are of considerable interest because of their use in magnetic recording tape, ferrofluid, magnetic resonance imaging, drug delivery, and treatment of cancer. The specific morphology of nanoparticles confers an ability to load, carry, and release different types of drugs. We synthesized superparamagnetic nanoparticles containing pure iron oxide with a cubic inverse spinal structure. Fourier transform infrared spectra confirmed that these Fe3O4 nanoparticles could be successfully coated with active drug, and thermogravimetric and differential thermogravimetric analyses showed that the thermal stability of iron oxide nanoparticles coated with chitosan and 6-mercaptopurine (FCMP) was markedly enhanced. The synthesized Fe3O4 nanoparticles and the FCMP nanocomposite were generally spherical, with an average diameter of 9 nm and 19 nm, respectively. The release of 6-mercaptopurine from the FCMP nanocomposite was found to be sustained and governed by pseudo-second order kinetics. In order to improve drug loading and release behavior, we prepared a novel nanocomposite (FCMP-D), ie, Fe3O4 nanoparticles containing the same amounts of chitosan and 6-mercaptopurine but using a different solvent for the drug. The results for FCMP-D did not demonstrate "burst release" and the maximum percentage release of 6-mercaptopurine from the FCMP-D nanocomposite reached about 97.7% and 55.4% within approximately 2,500 and 6,300 minutes when exposed to pH 4.8 and pH 7.4 solutions, respectively. By MTT assay, the FCMP nanocomposite was shown not to be toxic to a normal mouse fibroblast cell line. Iron oxide coated with chitosan containing 6-mercaptopurine prepared using a coprecipitation method has the potential to be used as a controlled-release formulation. These nanoparticles may serve as an alternative drug delivery system for the treatment of cancer, with the added advantage of sparing healthy surrounding cells and tissue.

Preparation and characterization of 6-mercaptopurine-coated magnetite nanoparticles as a drug delivery system

PubMed Central

Dorniani, Dena; Hussein, Mohd Zobir bin; Kura, Aminu Umar; Fakurazi, Sharida; Shaari, Abdul Halim; Ahmad, Zalinah

2013-01-01

Background Iron oxide nanoparticles are of considerable interest because of their use in magnetic recording tape, ferrofluid, magnetic resonance imaging, drug delivery, and treatment of cancer. The specific morphology of nanoparticles confers an ability to load, carry, and release different types of drugs. Methods and results We synthesized superparamagnetic nanoparticles containing pure iron oxide with a cubic inverse spinal structure. Fourier transform infrared spectra confirmed that these Fe3O4 nanoparticles could be successfully coated with active drug, and thermogravimetric and differential thermogravimetric analyses showed that the thermal stability of iron oxide nanoparticles coated with chitosan and 6-mercaptopurine (FCMP) was markedly enhanced. The synthesized Fe3O4 nanoparticles and the FCMP nanocomposite were generally spherical, with an average diameter of 9 nm and 19 nm, respectively. The release of 6-mercaptopurine from the FCMP nanocomposite was found to be sustained and governed by pseudo-second order kinetics. In order to improve drug loading and release behavior, we prepared a novel nanocomposite (FCMP-D), ie, Fe3O4 nanoparticles containing the same amounts of chitosan and 6-mercaptopurine but using a different solvent for the drug. The results for FCMP-D did not demonstrate “burst release” and the maximum percentage release of 6-mercaptopurine from the FCMP-D nanocomposite reached about 97.7% and 55.4% within approximately 2,500 and 6,300 minutes when exposed to pH 4.8 and pH 7.4 solutions, respectively. By MTT assay, the FCMP nanocomposite was shown not to be toxic to a normal mouse fibroblast cell line. Conclusion Iron oxide coated with chitosan containing 6-mercaptopurine prepared using a coprecipitation method has the potential to be used as a controlled-release formulation. These nanoparticles may serve as an alternative drug delivery system for the treatment of cancer, with the added advantage of sparing healthy surrounding cells and tissue. PMID:24106420

The antihypertensive effect of orally administered nifedipine-loaded nanoparticles in spontaneously hypertensive rats

PubMed Central

Il Kim, Young; Fluckiger, Laurence; Hoffman, Maurice; Lartaud-Idjouadiene, Isabelle; Atkinson, Jeffrey; Maincent, Philippe

1997-01-01

The therapeutic use of nifedipine is limited by the rapidity of the onset of its action and its short biological half-life. In order to produce a form devoid of these disadvantages we made nanoparticles of nifedipine from three different polymers, poly-ε-caprolactone (PCL), polylactic and glycolic acid (1 : 1) copolymers (PLAGA), and Eudragit RL/RS (Eudragit). Nifedipine in polyethylene glycol 400 (PEG) solution was used as a control.The average diameters of the nanoparticles ranged from 0.12 to 0.21 μm; the encapsulation ratio was 82% to 88%.In spontaneously hypertensive rats (SHR), the initial rapid fall in systolic arterial blood pressure following oral administration of nifedipine in PEG solution (from 193±3 to 102±2 mmHg) was not seen following administration of the same dose in Eudragit nanoparticles (from 189±2 to 156±2 mmHg); with PCL and PLAGA nanoparticles the initial fall in blood pressure was significantly reduced (nadirs PCL 124±2 and PLAGA 113±2 mmHg). Ten hours following administration, blood pressure in rats administered the nifedipine/PEG preparation had returned to normal (183±3 mmHg) whereas that of animals given nifedipine in nanoparticles (PCL 170±3, PLAGA 168±2, Eudragit 160±3 mmHg) was still significantly reduced.All of the nanoparticle dosage forms decreased Cmax and increased Tmax and the mean residence time (MRT) values. Relative bioavailability was significantly increased with Eudragit nanoparticles compared to the nifedipine/PEG solution.There was an inverse linear correlation between the fall in blood pressure and plasma nifedipine concentration with all preparations.The nanoparticle nifedipine preparations represent sustained release forms with increased bioavailability, a less pronounced initial antihypertensive effect and a long-lasting action. PMID:9031742

Ex vivo assessment of polyol coated-iron oxide nanoparticles for MRI diagnosis applications: toxicological and MRI contrast enhancement effects

NASA Astrophysics Data System (ADS)

Bomati-Miguel, Oscar; Miguel-Sancho, Nuria; Abasolo, Ibane; Candiota, Ana Paula; Roca, Alejandro G.; Acosta, Milena; Schwartz, Simó; Arus, Carles; Marquina, Clara; Martinez, Gema; Santamaria, Jesus

2014-03-01

Polyol synthesis is a promising method to obtain directly pharmaceutical grade colloidal dispersion of superparamagnetic iron oxide nanoparticles (SPIONs). Here, we study the biocompatibility and performance as T2-MRI contrast agents (CAs) of high quality magnetic colloidal dispersions (average hydrodynamic aggregate diameter of 16-27 nm) consisting of polyol-synthesized SPIONs (5 nm in mean particle size) coated with triethylene glycol (TEG) chains (TEG-SPIONs), which were subsequently functionalized to carboxyl-terminated meso-2-3-dimercaptosuccinic acid (DMSA) coated-iron oxide nanoparticles (DMSA-SPIONs). Standard MTT assays on HeLa, U87MG, and HepG2 cells revealed that colloidal dispersions of TEG-coated iron oxide nanoparticles did not induce any loss of cell viability after 3 days incubation with dose concentrations below 50 μg Fe/ml. However, after these nanoparticles were functionalized with DMSA molecules, an increase on their cytotoxicity was observed, so that particles bearing free terminal carboxyl groups on their surface were not cytotoxic only at low concentrations (<10 μg Fe/ml). Moreover, cell uptake assays on HeLa and U87MG and hemolysis tests have demonstrated that TEG-SPIONs and DMSA-SPIONs were well internalized by the cells and did not induce any adverse effect on the red blood cells at the tested concentrations. Finally, in vitro relaxivity measurements and post mortem MRI studies in mice indicated that both types of coated-iron oxide nanoparticles produced higher negative T2-MRI contrast enhancement than that measured for a similar commercial T2-MRI CAs consisting in dextran-coated ultra-small iron oxide nanoparticles (Ferumoxtran-10). In conclusion, the above attributes make both types of as synthesized coated-iron oxide nanoparticles, but especially DMSA-SPIONs, promising candidates as T2-MRI CAs for nanoparticle-enhanced MRI diagnosis applications.

Oligonucleotide flexibility dictates crystal quality in DNA-programmable nanoparticle superlattices.

PubMed

Senesi, Andrew J; Eichelsdoerfer, Daniel J; Brown, Keith A; Lee, Byeongdu; Auyeung, Evelyn; Choi, Chung Hang J; Macfarlane, Robert J; Young, Kaylie L; Mirkin, Chad A

2014-11-12

The evolution of crystallite size and microstrain in DNA-mediated nanoparticle superlattices is dictated by annealing temperature and the flexibility of the interparticle bonds. This work addresses a major challenge in synthesizing optical metamaterials based upon noble metal nanoparticles by enabling the crystallization of large nanoparticles (100 nm diameter) at high volume fractions (34% metal). © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Deposition of functional nanoparticle thin films by resonant infrared laser ablation.

NASA Astrophysics Data System (ADS)

Haglund, Richard; Johnson, Stephen; Park, Hee K.; Appavoo, Kannatessen

2008-03-01

We have deposited thin films containing functional nanoparticles, using tunable infrared light from a picosecond free-electron laser (FEL). Thin films of the green light-emitting molecule Alq3 were first deposited by resonant infrared laser ablation at 6.68 μm, targeting the C=C ring mode of the Alq3. TiO2 nanoparticles 50-100 nm diameter were then suspended in a water matrix, frozen, and transferred by resonant infrared laser ablation at 2.94 μm through a shadow mask onto the Alq3 film. Photoluminescence was substantially enhanced in the regions of the film covered by the TiO2 nanoparticles. In a second experiment, gold nanoparticles with diameters in the range of 50-100 nm were suspended in the conducting polymer and anti-static coating material PEDOT:PSS, which was diluted by mixing with N-methyl pyrrolidinone (NMP). The gold nanoparticle concentration was 8-10% by weight. The mixture was frozen and then ablated by tuning the FEL to 3.47 μm, the C-H stretch mode of NMP. Optical spectroscopy of the thin film deposited by resonant infrared laser ablation exhibited the surface-plasmon resonance characteristic of the Au nanoparticles. These experiments illustrate the versatility of matrix-assisted resonant infrared laser ablation as a technique for depositing thin films containing functionalized nanoparticles.

A fast and remote magnetonanothermometry for a liquid environment

NASA Astrophysics Data System (ADS)

He, Le; Liu, Wenzhong; Xie, Qingguo; Pi, Shiqiang; Morais, P. C.

2016-02-01

This study reports on a new approach for remote nanothermometry with short response time (milliseconds) aiming to operate in liquid media using AC susceptibility components of a suspended magnetic nanoparticle subjected to the Brownian relaxation mechanism. A simple, low cost, and accurate system was designed to measure AC susceptibility using an AC magnetic field at small amplitude (6 Oe) and frequency range (5 kHz) superimposed on a weak DC magnetic field (up to 30 Oe). A model based on the AC susceptibility of magnetic nanoparticles (30 nm average diameter) was constructed to describe the temperature measurement sensitivity of the dominated Brownian relaxation time. A new approach for remote nanothermometry was achieved with measured AC susceptibility by the designed system and the proposed model. Our experimental results show that our magnetonanothermometer allows temperature errors lower than 0.3 K with standard deviations lower than 0.1 K in the temperature range from 310 to 320 K.

Estimation of lattice strain in nanocrystalline RuO2 by Williamson-Hall and size-strain plot methods

NASA Astrophysics Data System (ADS)

Sivakami, R.; Dhanuskodi, S.; Karvembu, R.

2016-01-01

RuO2 nanoparticles (RuO2 NPs) have been successfully synthesized by the hydrothermal method. Structure and the particle size have been determined by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and transmission electron microscopy (TEM). UV-Vis spectra reveal that the optical band gap of RuO2 nanoparticles is red shifted from 3.95 to 3.55 eV. BET measurements show a high specific surface area (SSA) of 118-133 m2/g and pore diameter (10-25 nm) has been estimated by Barret-Joyner-Halenda (BJH) method. The crystallite size and lattice strain in the samples have been investigated by Williamson-Hall (W-H) analysis assuming uniform deformation, deformation stress and deformation energy density, and the size-strain plot method. All other relevant physical parameters including stress, strain and energy density have been calculated. The average crystallite size and the lattice strain evaluated from XRD measurements are in good agreement with the results of TEM.

Continuous, size and shape-control synthesis of hollow silica nanoparticles enabled by a microreactor-assisted rapid mixing process.

PubMed

He, Yujuan; Kim, Ki-Joong; Chang, Chih-Hung

2017-06-09

Hollow silica nanoparticles (HSNPs) were synthesized using a microreactor-assisted system with a hydrodynamic focusing micromixer. Due to the fast mixing of each precursor in the system, the poly(acrylic acid) (PAA) thermodynamic-locked (TML) conformations were protected from their random aggregations by the immediately initiated growth of silica shells. When altering the mixing time through varying flow rates and flow rate ratios, the different degrees of the aggregation of PAA TML conformations were observed. The globular and necklace-like TML conformations were successfully captured by modifying the PAA concentration at the optimized mixing condition. Uniform HSNPs with an average diameter ∼30 nm were produced from this system. COMSOL numerical models was established to investigate the flow and concentration profiles, and their effects on the formation of PAA templates. Finally, the quality and utility of these uniform HSNPs were demonstrated by the fabrication of antireflective thin films on monocrystalline photovoltaic cells which showed a 3.8% increase in power conversion efficiency.

Gold nanoparticles stabilized by poly(4-vinylpyridine) grafted cellulose nanocrystals as efficient and recyclable catalysts.

PubMed

Zhang, Zhen; Sèbe, Gilles; Wang, Xiaosong; Tam, Kam C

2018-02-15

pH-responsive poly(4-vinylpyridine) (P4VP) grafted cellulose nanocrystals (P4VP-g-CNC) were prepared by Surface-Initiated Atom Transfer Radical Polymerization (SI-ATRP) and subsequently used to stabilize gold nanoparticles (Au NPs) as efficient and recyclable nanocatalysts for the reduction of 4-nitrophenol (4NP). The presence of P4VP brushes on the CNC surface controlled the growth of Au NPs yielding smaller averaged diameter compared to Au NPs deposited directly on pristine CNC. The catalytic performances of pristine Au NPs, Au@CNC and Au@P4VP-g-CNC were compared by measuring the turnover frequency (TOF) for the catalytic reduction of 4NP. Compared to pristine Au NPs, the catalytic activity of Au@CNC and Au@P4VP-g-CNC were 10 and 24 times better. Moreover, the Au@P4VP-g-CNC material could be recovered via flocculation at pH>5, and the recycled nanocatalyst remained highly active. Copyright © 2017 Elsevier Ltd. All rights reserved.

Influence of silver nanoparticles on the spectroscopic properties of Sm{sup 3+} doped boro-phosphate glasses

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

Suthanthirakumar, P.; Marimuthu, K., E-mail: emari-ram2000@yahoo.com

The Sm{sup 3+} doped novel boro-phosphate glasses containing silver nanoparticles (NPs) (SmBPxA) have been prepared following the melt quenching technique and their structural and spectroscopic behavior were studied through HR-TEM, optical absorption and photoluminescence spectral measurements. The TEM analysis validates the existence of Ag NPs with an average diameter of ~8 nm. The Surface plasmon resonance (SPR) band of silver NPs was found at around 600 nm from the absorption spectrum of the Sm{sup 3+} ions free glass sample. The optical band gap energy (E{sub opt}) corresponding to the direct and indirect allowed transitions and the Urbach energy (ΔE) valuesmore » were determined from the absorption spectral measurements. The luminescence intensity is found to get enhance when the Ag NPs were embedded along with the Sm{sup 3+} ions in the prepared glasses due to the local electric field effect around the rare earth (RE) ion site produced by the SPR of Ag NPs.« less

Continuous, size and shape-control synthesis of hollow silica nanoparticles enabled by a microreactor-assisted rapid mixing process

NASA Astrophysics Data System (ADS)

He, Yujuan; Kim, Ki-Joong; Chang, Chih-Hung

2017-06-01

Hollow silica nanoparticles (HSNPs) were synthesized using a microreactor-assisted system with a hydrodynamic focusing micromixer. Due to the fast mixing of each precursor in the system, the poly(acrylic acid) (PAA) thermodynamic-locked (TML) conformations were protected from their random aggregations by the immediately initiated growth of silica shells. When altering the mixing time through varying flow rates and flow rate ratios, the different degrees of the aggregation of PAA TML conformations were observed. The globular and necklace-like TML conformations were successfully captured by modifying the PAA concentration at the optimized mixing condition. Uniform HSNPs with an average diameter ∼30 nm were produced from this system. COMSOL numerical models was established to investigate the flow and concentration profiles, and their effects on the formation of PAA templates. Finally, the quality and utility of these uniform HSNPs were demonstrated by the fabrication of antireflective thin films on monocrystalline photovoltaic cells which showed a 3.8% increase in power conversion efficiency.

Protein Attachment on Nanodiamonds.

PubMed

Lin, Chung-Lun; Lin, Cheng-Huang; Chang, Huan-Cheng; Su, Meng-Chih

2015-07-16

A recent advance in nanotechnology is the scale-up production of small and nonaggregated diamond nanoparticles suitable for biological applications. Using detonation nanodiamonds (NDs) with an average diameter of ∼4 nm as the adsorbents, we have studied the static attachment of three proteins (myoglobin, bovine serum albumin, and insulin) onto the nanoparticles by optical spectroscopy, mass spectrometry, and dynamic light scattering, and electrophoretic zeta potential measurements. Results show that the protein surface coverage is predominantly determined by the competition between protein-protein and protein-ND interactions, giving each protein a unique and characteristic structural configuration in its own complex. Specifically, both myoglobin and bovine serum albumin show a Langmuir-type adsorption behavior, forming 1:1 complexes at saturation, whereas insulin folds into a tightly bound multimer before adsorption. The markedly different adsorption patterns appear to be independent of the protein concentration and are closely related to the affinity of the individual proteins for the NDs. The present study provides a fundamental understanding for the use of NDs as a platform for nanomedical drug delivery.

Silver Nanoparticles Synthesized Using Caesalpinia sappan Extract as Potential Novel Nanoantibiotics Against Methicillin-Resistant Staphylococcus aureus.

PubMed

Jun, Sang Hui; Cha, Song-Hyun; Kim, Jae-Hyun; Yoon, Minho; Cho, Seonho; Park, Youmie

2015-08-01

Silver nanoparticles (AgNPs) have been shown to be effective antibacterial agents against methicillin-resistant Staphylococcus aureus (MRSA). In this study, AgNPs were synthesized using Caesalpinia sappan extract as a reducing agent to convert Ag+ to AgNPs. Seven stabilizers (surfactants and polymers) were added during the reduction step to increase the colloidal stability and to enhance the antibacterial activity of the AgNPs. Spherical and amorphous particles were primarily observed, with estimated diameters ranging from 30.2 to 47.5 nm. X-ray diffraction confirmed the face centered cubic structures of the AgNPs. Among the employed stabilizers, the cationic surfactant cetyltrimethylammonium bromide (CTAB) exhibited the highest antibacterial activity against 19 strains of MRSA, followed by polyvinylpyrrolidone (PVP, average molecular weight of 10,000). In contrast, the anionic surfactants sodium dodecyl sulfate (SDS) and sodium dodecylbenzene sulfonate (NaDDBS) did not exhibit any significant antibacterial activity, suggesting that the cationic surfactant head group contributed to the higher antibacterial activity of the AgNPs against MRSA.

Formation of Porous Germanium Layers by Silver-Ion Implantation

NASA Astrophysics Data System (ADS)

Stepanov, A. L.; Vorob'ev, V. V.; Nuzhdin, V. I.; Valeev, V. F.; Osin, Yu. N.

2018-04-01

We propose a method for the formation of porous germanium ( P-Ge) layers containing silver nanoparticles by means of high-dose implantation of low-energy Ag+ ions into single-crystalline germanium ( c-Ge). This is demonstrated by implantation of 30-keV Ag+ ions into a polished c-Ge plate to a dose of 1.5 × 1017 ion/cm2 at an ion beam-current density of 5 μA/cm2. Examination by high-resolution scanning electron microscopy (SEM), atomic-force microscopy (AFM), X-ray diffraction (XRD), energy-dispersive X-ray (EDX) microanalysis, and reflection high-energy electron diffraction (RHEED) showed that the implantation of silver ions into c-Ge surface led to the formation of a P-Ge layer with spongy structure comprising a network of interwoven nanofibers with an average diameter of ˜10-20 nm Ag nanoparticles on the ends of fibers. It is also established that the formation of pores during Ag+ ion implantation is accompanied by effective sputtering of the Ge surface.

Nanocomposite thin films for high temperature optical gas sensing of hydrogen

DOEpatents

Ohodnicki, Jr., Paul R.; Brown, Thomas D.

2013-04-02

The disclosure relates to a plasmon resonance-based method for H.sub.2 sensing in a gas stream at temperatures greater than about 500.degree. C. utilizing a hydrogen sensing material. The hydrogen sensing material is comprised of gold nanoparticles having an average nanoparticle diameter of less than about 100 nanometers dispersed in an inert matrix having a bandgap greater than or equal to 5 eV, and an oxygen ion conductivity less than approximately 10.sup.-7 S/cm at a temperature of 700.degree. C. Exemplary inert matrix materials include SiO.sub.2, Al.sub.2O.sub.3, and Si.sub.3N.sub.4 as well as modifications to modify the effective refractive indices through combinations and/or doping of such materials. At high temperatures, blue shift of the plasmon resonance optical absorption peak indicates the presence of H.sub.2. The method disclosed offers significant advantage over active and reducible matrix materials typically utilized, such as yttria-stabilized zirconia (YSZ) or TiO.sub.2.

Nanocomposite thin films for optical gas sensing

DOEpatents

Ohodnicki, Paul R; Brown, Thomas D

2014-06-03

The disclosure relates to a plasmon resonance-based method for gas sensing in a gas stream utilizing a gas sensing material. In an embodiment the gas stream has a temperature greater than about 500.degree. C. The gas sensing material is comprised of gold nanoparticles having an average nanoparticle diameter of less than about 100 nanometers dispersed in an inert matrix having a bandgap greater than or equal to 5 eV, and an oxygen ion conductivity less than approximately 10.sup.-7 S/cm at a temperature of 700.degree. C. Exemplary inert matrix materials include SiO.sub.2, Al.sub.2O.sub.3, and Si.sub.3N.sub.4 as well as modifications to modify the effective refractive indices through combinations and/or doping of such materials. Changes in the chemical composition of the gas stream are detected by changes in the plasmon resonance peak. The method disclosed offers significant advantage over active and reducible matrix materials typically utilized, such as yttria-stabilized zirconia (YSZ) or TiO.sub.2.

Antiviral activity of silver nanoparticle/chitosan composites against H1N1 influenza A virus

NASA Astrophysics Data System (ADS)

Mori, Yasutaka; Ono, Takeshi; Miyahira, Yasushi; Nguyen, Vinh Quang; Matsui, Takemi; Ishihara, Masayuki

2013-02-01

Silver nanoparticle (Ag NP)/chitosan (Ch) composites with antiviral activity against H1N1 influenza A virus were prepared. The Ag NP/Ch composites were obtained as yellow or brown floc-like powders following reaction at room temperature in aqueous medium. Ag NPs (3.5, 6.5, and 12.9 nm average diameters) were embedded into the chitosan matrix without aggregation or size alternation. The antiviral activity of the Ag NP/Ch composites was evaluated by comparing the TCID50 ratio of viral suspensions treated with the composites to untreated suspensions. For all sizes of Ag NPs tested, antiviral activity against H1N1 influenza A virus increased as the concentration of Ag NPs increased; chitosan alone exhibited no antiviral activity. Size dependence of the Ag NPs on antiviral activity was also observed: antiviral activity was generally stronger with smaller Ag NPs in the composites. These results indicate that Ag NP/Ch composites interacting with viruses exhibit antiviral activity.

Developmental Toxicity of Nanoparticles on the Brain.

PubMed

Umezawa, Masakazu; Onoda, Atsuto; Takeda, Ken

2017-01-01

The toxicity of nanoparticles (nanotoxicology) is being investigated to understand both the health impacts of atmospheric ultrafine particles-the size of which is a fraction (<0.1 μm aerodynamic diameter) of that of PM 2.5 (<2.5 μm diameter)-and the safer use of engineered nanomaterials. Developmental toxicity of nanoparticles has been studied since their transfer from pregnant body to fetal circulation and offspring body was first reported. Here we reviewed the developmental toxicity of nanoparticles on the brain, one of the most important organs in maintenance of mental health and high quality of life. Recently the dose- and size-dependency of transplacental nanoparticle transfer to the fetus was reported. It is important to understand both the mechanism of direct effect of nanoparticles transferred to the fetus and offspring and the indirect effect mediated by induction of oxidative stress and inflammation in the pregnant body. Locomotor activity, learning and memory, motor coordination, and social behavior were reported as potential neurobehavioral targets of maternal nanoparticle exposure. Histopathologically, brain perivascular cells, including perivascular macrophages and surrounding astrocytes, have an important role in waste clearance from the brain parenchyma. They are potentially the most sensitive target of maternal exposure to low-dose nanoparticles. Further investigations will show the detailed mechanism of developmental toxicity of nanoparticles and preventive strategies against intended and unintended nanoparticle exposure. This knowledge will contribute to the safer design of nanoparticles through the development of sensitive and quantitative endpoints for prediction of their developmental toxicity.

Inhibition of HIV Fusion with Multivalent Gold Nanoparticles

PubMed Central

Bowman, Mary-Catherine; Ballard, T. Eric; Ackerson, Christopher J.; Feldheim, Daniel L.; Margolis, David M.; Melander, Christian

2010-01-01

The design and synthesis of a multivalent gold nanoparticle therapeutic is presented. SDC-1721, a fragment of the potent HIV inhibitor TAK-779, was synthesized and conjugated to 2.0 nm diameter gold nanoparticles. Free SDC-1721 had no inhibitory effect on HIV infection; however, the (SDC-1721)-gold nanoparticle conjugates displayed activity comparable to that of TAK-779. This result suggests that multivalent presentation of small molecules on gold nanoparticle surfaces can convert inactive drugs into potent therapeutics. PMID:18473457

Dendronization-induced phase-transfer, stabilization and self-assembly of large colloidal Au nanoparticles

NASA Astrophysics Data System (ADS)

Malassis, Ludivine; Jishkariani, Davit; Murray, Christopher B.; Donnio, Bertrand

2016-07-01

The phase-transfer of CTAB-coated aqueous, spherical gold nanoparticles, with metallic core diameters ranging from ca. 27 to 54 nm, into organic solvents by exchanging the primitive polar bilayer with lipophilic, disulfide dendritic ligands is reported. The presence of such a thick nonpolar organic shell around these large nanoparticles enhances their stabilization against aggregation, in addition to enabling their transfer into a variety of solvents such as chloroform, toluene or tetrahydrofuran. Upon the slow evaporation of a chloroform suspension deposited on a solid support, the dendronized hybrids were found to self-assemble into ring structures of various diameters. Moreover, their self-assembly at the liquid-air interface affords the formation of fairly long-range ordered monolayers, over large areas, that can then be entirely transferred onto solid substrates.The phase-transfer of CTAB-coated aqueous, spherical gold nanoparticles, with metallic core diameters ranging from ca. 27 to 54 nm, into organic solvents by exchanging the primitive polar bilayer with lipophilic, disulfide dendritic ligands is reported. The presence of such a thick nonpolar organic shell around these large nanoparticles enhances their stabilization against aggregation, in addition to enabling their transfer into a variety of solvents such as chloroform, toluene or tetrahydrofuran. Upon the slow evaporation of a chloroform suspension deposited on a solid support, the dendronized hybrids were found to self-assemble into ring structures of various diameters. Moreover, their self-assembly at the liquid-air interface affords the formation of fairly long-range ordered monolayers, over large areas, that can then be entirely transferred onto solid substrates. Electronic supplementary information (ESI) available: TEM microscope images. See DOI: 10.1039/c6nr03404g

Effect of BaTiO3 nano-particles on breakdown performance of propylene carbonate.

PubMed

Hou, Yanpan; Zhang, Zicheng; Zhang, Jiande; Liu, Zhuofeng; Song, Zuyin

2015-05-01

As an alternative to water, propylene carbonate (PC) has a good application prospect in the compact pulsed power sources for its breakdown strength higher than that of water, resistivity bigger than 10(9) Ω m, and low freezing temperature (-49 °C). In this paper, the investigation into dielectric breakdown of PC and PC-based nano-fluids (NFs) subjected to high amplitude electric field is presented with microsecond pulses applied to a 1 mm gap full of PC or NFs between spherical electrodes. One kind of NF is composed of PC mixed with 0.5-1.4 vol. % BaTiO3 (BT) nano-particles of mean diameter ≈100 nm and another is mixed with 0.3-0.8 vol. % BT nano-particles of mean diameter ≈30 nm. The experimental results demonstrate the rise of permittivity and improvement of the breakdown strength of NFs compared with PC. Moreover, it is found that there exists an optimum fraction for these NFs corresponding to tremendous surface area in nano-composites with finite mesoscopic thickness. In concrete, the dielectric breakdown voltage of NFs is 33% higher than that of PC as the volume concentration of nano-particles with a 100 nm diameter is 0.9% and the breakdown voltage of NFs is 40% higher as the volume concentration of nano-particles with a 30 nm diameter is 0.6%. These phenomena are considered as the dielectric breakdown voltage of PC-based NFs is increased because the interfaces between nano-fillers and PC matrices provide myriad trap sites for charge carriers, which play a dominant role in the breakdown performance of NFs.

Experiment and Artificial Neural Network Prediction of Thermal Conductivity and Viscosity for Alumina-Water Nanofluids

PubMed Central

Zhao, Ningbo; Li, Zhiming

2017-01-01

To effectively predict the thermal conductivity and viscosity of alumina (Al2O3)-water nanofluids, an artificial neural network (ANN) approach was investigated in the present study. Firstly, using a two-step method, four Al2O3-water nanofluids were prepared respectively by dispersing different volume fractions (1.31%, 2.72%, 4.25%, and 5.92%) of nanoparticles with the average diameter of 30 nm. On this basis, the thermal conductivity and viscosity of the above nanofluids were analyzed experimentally under various temperatures ranging from 296 to 313 K. Then a radial basis function (RBF) neural network was constructed to predict the thermal conductivity and viscosity of Al2O3-water nanofluids as a function of nanoparticle volume fraction and temperature. The experimental results showed that both nanoparticle volume fraction and temperature could enhance the thermal conductivity of Al2O3-water nanofluids. However, the viscosity only depended strongly on Al2O3 nanoparticle volume fraction and was increased slightly by changing temperature. In addition, the comparative analysis revealed that the RBF neural network had an excellent ability to predict the thermal conductivity and viscosity of Al2O3-water nanofluids with the mean absolute percent errors of 0.5177% and 0.5618%, respectively. This demonstrated that the ANN provided an effective way to predict the thermophysical properties of nanofluids with limited experimental data. PMID:28772913

Experiment and Artificial Neural Network Prediction of Thermal Conductivity and Viscosity for Alumina-Water Nanofluids.

PubMed

Zhao, Ningbo; Li, Zhiming

2017-05-19

To effectively predict the thermal conductivity and viscosity of alumina (Al₂O₃)-water nanofluids, an artificial neural network (ANN) approach was investigated in the present study. Firstly, using a two-step method, four Al₂O₃-water nanofluids were prepared respectively by dispersing different volume fractions (1.31%, 2.72%, 4.25%, and 5.92%) of nanoparticles with the average diameter of 30 nm. On this basis, the thermal conductivity and viscosity of the above nanofluids were analyzed experimentally under various temperatures ranging from 296 to 313 K. Then a radial basis function (RBF) neural network was constructed to predict the thermal conductivity and viscosity of Al₂O₃-water nanofluids as a function of nanoparticle volume fraction and temperature. The experimental results showed that both nanoparticle volume fraction and temperature could enhance the thermal conductivity of Al₂O₃-water nanofluids. However, the viscosity only depended strongly on Al₂O₃ nanoparticle volume fraction and was increased slightly by changing temperature. In addition, the comparative analysis revealed that the RBF neural network had an excellent ability to predict the thermal conductivity and viscosity of Al₂O₃-water nanofluids with the mean absolute percent errors of 0.5177% and 0.5618%, respectively. This demonstrated that the ANN provided an effective way to predict the thermophysical properties of nanofluids with limited experimental data.

Distinguishing magnetic blocking and surface spin-glass freezing in nickel ferrite nanoparticles

NASA Astrophysics Data System (ADS)

Nadeem, K.; Krenn, H.; Traussing, T.; Letofsky-Papst, I.

2011-01-01

Nickel ferrite nanoparticles dispersed in SiO2 matrix have been synthesized by sol-gel method. Structural analysis has been performed by using x-ray diffraction and transmission electron microscopy. Magnetic properties have been investigated by using superconducting quantum interference device magnetometry. In addition to the average blocking temperature peak at TB=120 K measured by a zero field cooled temperature scan of the dc susceptibility, an additional hump near 15 K is observed. Temperature dependent out-of-phase ac susceptibility shows the same features: one broad peak at high temperature and a second narrow peak at low temperature. The high temperature peak corresponds to magnetic blocking of individual nanoparticles, while the low temperature peak is attributed to surface spin-glass freezing which becomes dominant for decreasing particle diameter. To prove the dynamics of the spin (dis)order in both regimes of freezing and blocking, the frequency dependent ac susceptibility is investigated under a biasing dc field. The frequency shift in the "frozen" low-temperature ac susceptibility peak is fitted to a dynamic scaling law with a critical exponent zv=7.5, which indicates a spin-glass phase. Exchange bias is turned on at low temperature which signifies the existence of a strong core-shell interaction. Aging and memory effects are further unique fingerprints of a spin-glass freezing on the surface of isolated magnetic nanoparticles.

Photodecomposition of volatile organic compounds using TiO2 nanoparticles.

PubMed

Jwo, Ching-Song; Chang, Ho; Kao, Mu-Jnug; Lin, Chi-Hsiang

2007-06-01

This study examined the photodecomposition of volatile organic compounds (VOCs) using TiO2 catalyst fabricated by the Submerged Arc Nanoparticle Synthesis System (SANSS). TiO2 catalyst was employed to decompose volatile organic compounds and compare with Degussa-P25 TiO2 in terms of decomposition efficiency. In the electric discharge manufacturing process, a Ti bar, applied as the electrode, was melted and vaporized under high temperature. The vaporized Ti powders were then rapidly quenched under low-temperature and low-pressure conditions in deionized water, thus nucleating and forming nanocrystalline powders uniformly dispersed in the base solvent. The average diameter of the TiO2 nanoparticles was 20 nm. X-ray diffraction analysis confirmed that the nanoparticles in the deionized water were Anatase type TiO2. It was found that gaseous toluene exposed to UV irradiation produced intermediates that were even harder to decompose. After 60-min photocomposition, Degussa-P25 TiO2 reduced the concentration of gaseous toluene to 8.18% while the concentration after decomposition by SANSS TiO2 catalyst dropped to 0.35%. Under UV irradiation at 253.7 +/- 184.9 nm, TiO2 prepared by SANSS can produce strong chemical debonding energy, thus showing great efficiency, superior to that of Degussa-P25 TiO2, in decomposing gaseous toluene and its intermediates.

Multifunctional guest-host particles engineered by reversal nanoimprint lithography

NASA Astrophysics Data System (ADS)

Ha, Uh-Myong; Kaban, Burhan; Tomita, Andreea; Krekić, Kristijan; Klintuch, Dieter; Pietschnig, Rudolf; Ehresmann, Arno; Holzinger, Dennis; Hillmer, Hartmut

2018-03-01

Particulate polymeric microfibers with incorporated europium(III)oxide (Eu2O3) nanoparticles were introduced as a magneto-photoluminescent multifunctional material fabricated via reversal nanoimprint lithography. To specifically address the volume properties of these guest-host particles, the guest, Eu2O3, was milled down to an average particle size of 350 nm in diameter and mixed with the host-polymer, AMONIL®, before in situ hardening in the imprint stamp. The variation of the fabrication process parameters, i.e. delay time, spin coating speed, as well as the concentration of Eu2O3 nanoparticles was proven to have a significant impact on both the structure quality and the stamp release of the microfibers with respect to the formation of a thinner residual layer. Structural characterization performed by SEM revealed optimum fabrication process parameters for a homogeneous spatial distribution of Eu2O3 nanoparticles within the microfibers while simultaneously avoiding the formation of undesired agglomerates. The magneto-photoluminescent properties of Eu2O3 nanoparticles, i.e. a red emission at 613 nm and a paramagnetic response, were found to be superimposed to the optic and the diamagnetic behaviors of AMONIL®. The results imply that guest-host interdependence of these properties can be excluded and that the suggested technique enables for specific tailoring of particulate multifunctional materials with focus on their volume properties.

Green synthesis, characterization and evaluation of biocompatibility of silver nanoparticles

NASA Astrophysics Data System (ADS)

Ahamed, Maqusood; Majeed Khan, M. A.; Siddiqui, M. K. J.; AlSalhi, Mohamad S.; Alrokayan, Salman A.

2011-04-01

Although green synthesis of silver nanoparticles (Ag NPs) by various plants and microorganisms has been reported, the potential of plants as biological materials for the synthesis of nanoparticles and their compatibility to biological systems is yet to be fully explored. In this study, we report a simple green method for the synthesis of Ag NPs using garlic clove extract as a reducing and stabilizing agent. In addition to green synthesis, biological response of Ag NPs in human lung epithelial A549 cells was also assessed. Ag NPs were rapidly synthesized using garlic clove extract and the formation of nanoparticles was observed within 30 min. The green synthesized Ag NPs were characterized using UV-vis spectrum, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), field emission transmission electron microscopy (FETEM), X-ray energy-dispersive spectroscopy (EDX) and dynamic light scattering (DLS). Characterization data demonstrated that the particles were crystalline in nature and spherical shaped with an average diameter of 12 nm. Measurements of cell viability, cell membrane integrity and intracellular production of reactive oxygen species have shown that the green synthesized Ag NPs were nontoxic to human lung epithelial A549 cells. This study demonstrated a simple, cost-effective and environmentally benign synthesis of Ag NPs with excellent biocompatibility to human lung epithelial A549 cells. This preliminary in vitro investigation needs to be followed up by future studies with various biological systems.

Methotrexate-conjugated magnetic nanoparticles for thermochemotherapy and magnetic resonance imaging of tumor

NASA Astrophysics Data System (ADS)

Gao, Fuping; Yan, Zixing; Zhou, Jing; Cai, Yuanyuan; Tang, Jintian

2012-10-01

There is significant interest in recent years in developing magnetic nanoparticles (MNPs) having multifunctional characteristics with complimentary roles. In this study, methotrexate (MTX) was conjugated on the iron oxide magnetic nanoparticles surface via a poly(ethyleneimine) self-assembled monolayer (MTX-MNPs). The novel platform combined cancer chemotherapy, hyperthermia and potential monitoring of the progression of disease through magnetic resonance imaging (MRI). The conjugation of MTX on the magnetite surface was confirmed by Fourier transform infrared spectroscopy and change of zeta potential. Transmission electron microscope (TEM) showed that MTX-MNPs were morphologically spherical. The average diameter of MTX-MNPs was 30.1 ± 5.2 nm determined by dynamic light scattering. Magnetic measurements revealed that the saturation magnetization of MTX-MNPs reached 68.8 emu/g and the nanoparticles were superparamagnetic. The MTX-MNPs had good heating properties in an alternating magnetic field. TEM results showed that a larger number of MTX-MNPs were internalized into the MCF-7 cellular cytoplasm compared with the MNPs. The MTX-MNPs demonstrated highly synergistic antiproliferative effects of simultaneous chemotherapy and hyperthermia in MCF-7 breast cancer cells. A significant negative contrast enhancement was observed with magnetic resonance phantom imaging for MCF-7 cells over L929cells, when both were cultured with the nanoconjugate. The MTX-MNPs with combined characteristics of thermochemotherapy and MRI could be of high clinical significance in the treatment of tumor.

Water treatment with exceptional virus inactivation using activated carbon modified with silver (Ag) and copper oxide (CuO) nanoparticles.

PubMed

Shimabuku, Quelen Letícia; Arakawa, Flávia Sayuri; Fernandes Silva, Marcela; Ferri Coldebella, Priscila; Ueda-Nakamura, Tânia; Fagundes-Klen, Márcia Regina; Bergamasco, Rosangela

2017-08-01

Continuous flow experiments (450 mL min -1 ) were performed in household filter in order to investigate the removal and/or inactivation of T4 bacteriophage, using granular activated carbon (GAC) modified with silver and/or copper oxide nanoparticles at different concentrations. GAC and modified GAC were characterized by X-ray diffractometry, specific surface area, pore size and volume, pore average diameter, scanning electron microscopy, transmission electron microscopy, zeta potential and atomic absorption spectroscopy. The antiviral activity of the produced porous media was evaluated by passing suspensions of T4 bacteriophage (∼10 5  UFP/mL) through filters. The filtered water was analyzed for the presence of the bacteriophage and the release of silver and copper oxide. The porous media containing silver and copper oxide nanoparticles showed high inactivation capacity, even reaching reductions higher than 3 log. GAC6 (GAC/Ag0.5%Cu1.0%) was effective in the bacteriophage inactivation, reaching 5.53 log reduction. The levels of silver and copper released in filtered water were below the recommended limits (100 ppb for silver and 1000 ppb for copper) in drinking water. From this study, it is possible to conclude that activated carbon modified with silver and copper oxide nanoparticles can be used as a filter for virus removal in the treatment of drinking water.

Heat transfer enhancement and entropy generation analysis of Al2O3-water nanofluid in an alternating oval cross-section tube using two-phase mixture model under turbulent flow

NASA Astrophysics Data System (ADS)

Najafi Khaboshan, Hasan; Nazif, Hamid Reza

2018-04-01

Heat transfer and turbulent flow of Al2O3-water nanofluid within alternating oval cross-section tube are numerically simulated using Eulerian-Eulerian two-phase mixture model. The primary goal of the present study is to investigate the effects of nanoparticles volume fraction, nanoparticles diameter and different inlet velocities on heat transfer, pressure drop and entropy generation characteristics of the alternating oval cross-section tube. For numerical simulation validation, the numerical results were compared with experimental data. Also, constant wall temperature boundary condition was considered on the tube wall. In addition, the comparison of thermal-hydraulic performance and the entropy generation characteristics between alternating oval cross-section tube and circular tube under same fluids were done. The results show that the heat transfer coefficient and pressure drop of alternating oval cross-section tube is more than base tube under same fluids. Also, these two parameters are increased when adding Al2O3 nanoparticle into water fluid, at any inlet velocity for both tubes. Furthermore, compared to the base fluid, the value of the heat transfer enhancement of nanofluid is higher than the increase of friction factor of nanofluid at the same given inlet boundary conditions. The results of entropy generation analysis illustrate that the total entropy generation increase with increasing the nanoparticles volume fraction and decreasing the nanoparticles diameter of nanofluid. The generation of thermal entropy is the main part of irreversibility, and Bejan number with an increase of the nanoparticles diameter slightly increases. Finally, at any given inlet velocity the frictional irreversibility is grown with an increase the nanoparticles volume fraction.

Influence of Temperature on the Colloidal Stability of Polymer-Coated Gold Nanoparticles in Cell Culture Media.

PubMed

Zyuzin, Mikhail V; Honold, Tobias; Carregal-Romero, Susana; Kantner, Karsten; Karg, Matthias; Parak, Wolfgang J

2016-04-06

The temperature-dependence of the hydrodynamic diameter and colloidal stability of gold-polymer core-shell particles with temperature-sensitive (poly(N-isopropylacrylamide)) and temperature-insensitive shells (polyallylaminine hydrochloride/polystyrensulfonate, poly(isobutylene-alt-maleic anhydride)-graft-dodecyl) are investigated in various aqueous media. The data demonstrate that for all nanoparticle agglomeration, i.e., increase in effective nanoparticle size, the presence of salts or proteins in the dispersion media has to be taken into account. Poly(N-isopropylacrylamide) coated nanoparticles show a reversible temperature-dependent increase in size above the volume phase transition of the polymer shell when they are dispersed in phosphate buffered saline or in media containing protein. In contrast, the nanoparticles coated with temperature-insensitive polymers show a time-dependent increase in size in phosphate buffered saline or in medium containing protein. This is due to time-dependent agglomeration, which is particularly strong in phosphate buffered saline, and induces a time-dependent, irreversible increase in the hydrodynamic diameter of the nanoparticles. This demonstrates that one has to distinguish between temperature- and time-induced agglomerations. Since the size of nanoparticles regulates their uptake by cells, temperature-dependent uptake of thermosensitive and non-thermosensitive nanoparticles by cells lines is compared. No temperature-specific difference between both types of nanoparticles could be observed. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sorting and measurement of single gold nanoparticles in an optofluidic chip

NASA Astrophysics Data System (ADS)

Shi, Y. Z.; Xiong, S.; Zhang, Y.; Chin, L. K.; Wu, J. H.; Chen, T. N.; Liu, A. Q.

2017-08-01

Gold nanoparticles have sparked strong interest owing to their unique optical and chemical properties. Their sizedependent refractive index and plasmon resonance are widely used for optical sorting, biomedicine and chemical sensing. However, there are only few examples of optical separation of different gold nanoparticles. Only separating 100-200 nm gold nanoparticles using wavelength selected resonance of the extinction spectrum has been demonstrated. This paper reports an optofluidic chip for sorting single gold nanoparticles using loosely overdamped optical potential wells, which are created by building optical and fluidic barriers. It is the first demonstration of sorting single nanoparticles with diameters ranging from 60 to 100 nm in a quasi-Bessel beam with an optical trapping stiffness from 10-10 to 10-9 N/m. The nanoparticles oscillate in the loosely overdamped potential wells with a displacement amplitude of 3-7 μm in the microchannel. The sizes and refractive indices of the nanoparticles can be determined from their trapping positions using Drude and Mie theory, with a resolution of 0.35 nm/μm for the diameter, 0.0034/μm and 0.0017/μm for the real and imaginary parts of the refractive index, respectively. Here we experimentally demonstrate the sorting of bacteria and protozoa on the optofluidic chip. The chip has high potential for the sorting and characterization of nanoparticles in biomedical applications such as tumour targeting, drug delivery and intracellular imaging.

SIMS depth profiling of working environment nanoparticles

NASA Astrophysics Data System (ADS)

Konarski, P.; Iwanejko, I.; Mierzejewska, A.

2003-01-01

Morphology of working environment nanoparticles was analyzed using sample rotation technique in secondary ion mass spectrometry (SIMS). The particles were collected with nine-stage vacuum impactor during gas tungsten arc welding (GTAW) process of stainless steel and shielded metal arc welding (SMAW) of mild steel. Ion erosion of 300-400 nm diameter nanoparticles attached to indium substrate was performed with 2 keV, 100 μm diameter, Ar + ion beam at 45° ion incidence and 1 rpm sample rotation. The results show that both types of particles have core-shell morphology. A layer of fluorine, chlorine and carbon containing compounds covers stainless steel welding fume particles. The cores of these particles are enriched in iron, manganese and chromium. Outer shell of mild steel welding fume particles is enriched in carbon, potassium, chlorine and fluorine, while the deeper layers of these nanoparticles are richer in main steel components.

Wrinkling of graphene membranes supported by silica nanoparticles on substrates

NASA Astrophysics Data System (ADS)

Yamamoto, Mahito; Cullen, William; Fuhrer, Michael; Einstein, Theodore; Department of Physics, University of Maryland Team

2011-03-01

The challenging endeavor of modulating the morphology of graphene via a patterned substrate to produce a controlled deformation has great potential importance for strain engineering the electronic properties of graphene. An essential step in this direction is to understand the response of graphene to substrate features of known geometry. Here we employ silica nanoparticles with a diameter of 10-100 nm to uniformly decorate Si O2 and mica substrates before depositing graphene, to promote nanoscale modulation of graphene geometry. The morphology of graphene on this modified substrate is then characterized by atomic force spectroscopy. We find that graphene on the substrate is locally raised by the supporting nanoparticles, and wrinkling propagates radially from the protrusions to form a ridge network which links the protrusions. We discuss the dependence of the wrinkled morphology on nanoparticle diameter and graphene thickness in terms of graphene elasticity and adhesion energy. Supported by NSF-MRSEC, Grant DMR 05-20471

The Effect of Metal Oxide on Nanoparticles from Thermite Reactions

ERIC Educational Resources Information Center

Moore, Lewis Ryan

2006-01-01

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

Role of SiO2 coating in multiferroic CoCr2O4 nanoparticles

NASA Astrophysics Data System (ADS)

Kamran, M.; Ullah, Asmat; Mehmood, Y.; Nadeem, K.; Krenn, H.

2017-02-01

Effect of silica (SiO2) coating concentration on structural and magnetic properties of multiferroic cobalt chromite (CoCr2O4) nanoparticles have been studied. The nanoparticles with average crystallite size in the range 19 to 28 nm were synthesised by sol-gel method. X-ray diffraction (XRD) analysis has verified the composition of single-phase cubic normal spinel structure of CoCr2O4 nanoparticles. The average crystallite size and cell parameter decreased with increasing SiO2 concentration. TEM image revealed that the shape of nanoparticles was non-spherical. Zero field cooled/field cooled (ZFC/FC) curves revealed that nanoparticles underwent a transition from paramagnetic (PM) state to collinear short-range ferrimagnetic (FiM) state, and this PM-FiM transition temperature decreased from 101 to 95 K with increasing SiO2 concentration or decreasing crystallite size. A conical spin state at Ts = 27 K was also observed for all the samples which decreased with decreasing average crystallite size. Low temperature lock-in transition was also observed in these nanoparticles at 12 K for uncoated nanoparticles which slightly shifted towards low temperature with decreasing average crystallite size. Saturation magnetization (Ms) showed decreasing trend with increasing SiO2 concentration, which was due to decrease in average crystallite size of nanoparticles and enhanced surface disorder in smaller nanoparticles. The temperature dependent AC-susceptibility also showed the decrease in the transition temperature (Tc), broadening of the Tc peak and decrease in magnetization with increasing SiO2 concentration or decreasing average crystallite size. In summary, the concentration of SiO2 has significantly affected the structural and magnetic properties of CoCr2O4 nanoparticles.

Surface modification of nanoporous alumina layers by deposition of Ag nanoparticles. Effect of alumina pore diameter on the morphology of silver deposit and its influence on SERS activity

NASA Astrophysics Data System (ADS)

Pisarek, Marcin; Nowakowski, Robert; Kudelski, Andrzej; Holdynski, Marcin; Roguska, Agata; Janik-Czachor, Maria; Kurowska-Tabor, Elżbieta; Sulka, Grzegorz D.

2015-12-01

Self-organized Al2O3 nanoporous/nanotubular (Al2O3-NP) oxide layers decorated with silver nanoparticles (Ag-NPs) exhibiting specific properties may serve as attractive SERS substrates for investigating the interactions between an adsorbate and adsorbent, or as stable platforms for detecting various organic compounds. This article presents the influence of the size of the alumina nanopores with a deposit of silver nanoparticles obtained by the magnetron sputtering technique on the morphology of silver film. Moreover, the effect of pore diameter on the intensity of SERS spectra in Ag-NPs/Al2O3-NP/Al composites has also been estimated. For such investigations we used pyridine as a probe molecule, since it has a large cross-section for Raman scattering. To characterize the morphology of the composite oxide layer Ag-NPs/Al2O3-NP/Al, before and after deposition of Ag-NPs by PVD methods (Physical Vapor Deposition), we used scanning electron microscopy (SEM) and atomic force microscopy (AFM). The surface analytical technique of surface-enhanced Raman spectroscopy (SERS) was used to investigate the surface activity of the composite. The results obtained show that, for a carefully controlled amount of Ag (0.020 mg/cm2 - deposited on the top of alumina nanopores whose average size varies from ∼86 nm up to ∼320 nm) in the composites investigated, pore size significantly affects SERS enhancement. We obtained distinctly higher intensities of SERS spectra for substrates with an Ag-NPs deposit having a larger diameter of the alumina nanopores. AFM results suggest that both the lateral and perpendicular distribution of Ag-NPs within and on the top of the largest pores is responsible for the highest SERS activity of the resulting Ag-NPs/Al2O3-NP/Al composite layer, since it produces a variety of cavities and slits which function as resonators for the adsorbed molecules. The Ag-NPs/MeOx-NP/Me composite layers obtained ensure a good reproducibility of the SERS measurements.

Synthesis and Size Dependent Reflectance Study of Water Soluble SnS Nanoparticles

PubMed Central

Xu, Ying; Al-Salim, Najeh; Tilley, Richard D.

2012-01-01

Near-monodispersed water soluble SnS nanoparticles in the diameter range of 3–6 nm are synthesized by a facile, solution based one-step approach using ethanolamine ligands. The optimal amount of triethanolamine is investigated. The effect of further heat treatment on the size of these SnS nanoparticles is discussed. Diffuse reflectance study of SnS nanoparticles agrees with predictions from quantum confinement model. PMID:28348295

Effect of nanoparticles size and polyelectrolyte on nanoparticles aggregation in a cellulose fibrous matrix

DOE PAGES

Raghuwanshi, Vikram Singh; Garusinghe, Uthpala Manavi; Ilavsky, Jan; ...

2017-09-18

Controlling nanoparticles (NPs) aggregation in cellulose/NPs composites allows to optimise NPs driven properties and their applications. Polyelectrolytes are used to control NPs aggregation and their retention within the fibrous matrix. Here in this study, we aim at evaluating how a polyelectrolyte (Cationic Polyacrylamide; CPAM, molecular weight: 13 MDa, charge: 50%, Radius of gyration: 30–36 nm) adsorbs and re-conforms onto the surface of silica(SiO 2) NPs differing in diameter (8, 22 and 74 nm) and to investigate the respective NPs aggregation in cellulose matrices. SEM shows the local area distribution of NPs in composites. Ultra-SAXS (USAXS) allows to evaluate the averagemore » NPs size distribution and the inter-particle interactions at length scale ranging from 1 to 1000 nm. USAXS data analysis reveals that CPAM covers multiple NPs of the smaller diameter (8 nm), presumably with a single chain to form large size NPs aggregates. As the NPs diameter is increased to 22 nm, CPAM re-conforms over NP surface forming a large shell of thickness 5.5 nm. For the composites with NPs of diameter 74 nm, the CPAM chain re-conforms further onto NP surface and the surrounding shell thickness decreases to 2.2 nm. Lastly, structure factor analysis reveals higher structural ordering for NPs as increases their diameter, which is caused by different conformations adopted by CPAM onto NPs surface.« less

A Dense Poly(ethylene glycol) Coating Improves Penetration of Large Polymeric Nanoparticles within Brain Tissue

PubMed Central

Nance, Elizabeth A.; Woodworth, Graeme F.; Sailor, Kurt A.; Shih, Ting-Yu; Xu, Qingguo; Swaminathan, Ganesh; Xiang, Dennis; Eberhart, Charles; Hanes, Justin

2013-01-01

Prevailing opinion suggests that only substances up to 64 nm in diameter can move at appreciable rates through the brain extracellular space (ECS). This size range is large enough to allow diffusion of signaling molecules, nutrients, and metabolic waste products, but too small to allow efficient penetration of most particulate drug delivery systems and viruses carrying therapeutic genes, thereby limiting effectiveness of many potential therapies. We analyzed the movements of nanoparticles of various diameters and surface coatings within fresh human and rat brain tissue ex vivo and mouse brain in vivo. Nanoparticles as large as 114-nm in diameter diffused within the human and rat brain, but only if they were densely coated with poly(ethylene glycol) (PEG). Using these minimally adhesive PEG-coated particles, we estimated that human brain tissue ECS has some pores larger than 200 nm, and that more than one-quarter of all pores are ≥100 nm. These findings were confirmed in vivo in mice, where 40- and 100-nm, but not 200-nm, nanoparticles, spread rapidly within brain tissue, only if densely coated with PEG. Similar results were observed in rat brain tissue with paclitaxel-loaded biodegradable nanoparticles of similar size (85 nm) and surface properties. The ability to achieve brain penetration with larger nanoparticles is expected to allow more uniform, longer-lasting, and effective delivery of drugs within the brain, and may find use in the treatment of brain tumors, stroke, neuroinflammation, and other brain diseases where the blood-brain barrier is compromised or where local delivery strategies are feasible. PMID:22932224

Small Particle Driven Chain Disentanglements in Polymer Nanocomposites

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

Senses, Erkan; Ansar, Siyam M.; Kitchens, Christopher L.

2017-04-01

Using neutron spin-echo spectroscopy, X-ray photon correlation spectroscopy and bulk rheology, we studied the effect of particle size on the single chain dynamics, particle mobility, and bulk viscosity in athermal polyethylene oxide-gold nanoparticle composites. The results reveal an ≈ 25 % increase in the reptation tube diameter with addition of nanoparticles smaller than the entanglement mesh size (≈ 5 nm), at a volume fraction of 20 %. The tube diameter remains unchanged in the composite with larger (20 nm) nanoparticles at the same loading. In both cases, the Rouse dynamics is insensitive to particle size. These results provide a directmore » experimental observation of particle size driven disentanglements that can cause non-Einstein-like viscosity trends often observed in polymer nanocomposites.« less

Synthesis of 5-hydroxymethylfurural from carbohydrates using large-pore mesoporous tin phosphate.

PubMed

Dutta, Arghya; Gupta, Dinesh; Patra, Astam K; Saha, Basudeb; Bhaumik, Asim

2014-03-01

A large-pore mesoporous tin phosphate (LPSnP-1) material has been synthesized hydrothermally by using Pluronic P123 as the structure-directing agent. The material is composed of aggregated nanoparticles of 10-15 nm in diameter and has a BET surface area of 216 m(2)  g(-1) with an average pore diameter of 10.4 nm. This pore diameter is twice as large as that of mesoporous tin phosphate materials synthesized through the surfactant-templating pathways reported previously. LPSnP-1 shows excellent catalytic activity for the conversion of fructose, glucose, sucrose, cellobiose, and cellulose to 5-hydroxymethylfurfural (HMF) in a water/methyl isobutyl ketone biphasic solvent to give maximum yields of HMF of 77, 50, 51, 39, and 32 mol %, respectively, under microwave-assisted heating at 423 K. Under comparable reaction conditions, LPSnP-1 gives 12 % more HMF yield than a small-pore mesoporous tin phosphate catalyst that has an identical framework composition. This confirms the beneficial role of large mesopores and nanoscale particle morphology in catalytic reactions that involve bulky natural carbohydrate molecules. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Efficient drug delivery using SiO2-layered double hydroxide nanocomposites.

PubMed

Li, Li; Gu, Zi; Gu, Wenyi; Liu, Jian; Xu, Zhi Ping

2016-05-15

MgAl-layered double hydroxide (MgAl-LDH) nanoparticles have great potentials in drug and siRNA delivery. In this work, we used a nanodot-coating strategy to prepare SiO2 dot-coated layered double hydroxide (SiO2@MgAl-LDH) nanocomposites with good dispersibility and controllable size for drug delivery. The optimal SiO2@MgAl-LDH nanocomposite was obtained by adjusting synthetic parameters including the mass ratio of MgAl-LDH to SiO2, the mixing temperature and time. The optimal SiO2@MgAl-LDH nanocomposite was shown to have SiO2 nanodots (10-15nm in diameter) evenly deposited on the surface of MgAl-LDHs (110nm in diameter) with the plate-like morphology and the average hydrodynamic diameter of 170nm. We further employed SiO2@MgAl-LDH nanocomposite as a nanocarrier to deliver methotrexate (MTX), a chemotherapy drug, to the human osteosarcoma cell (U2OS) and found that MTX delivered by SiO2@MgAl-LDH nanocomposite apparently inhibited the U2OS cell growth. Copyright © 2016 Elsevier Inc. All rights reserved.

Mesoporous silica coatings for cephalosporin active release at the bone-implant interface

NASA Astrophysics Data System (ADS)

Rădulescu, Dragoş; Voicu, Georgeta; Oprea, Alexandra Elena; Andronescu, Ecaterina; Grumezescu, Valentina; Holban, Alina Maria; Vasile, Bogdan Stefan; Surdu, Adrian Vasile; Grumezescu, Alexandru Mihai; Socol, Gabriel; Mogoantă, Laurenţiu; Mogoşanu, George Dan; Balaure, Paul Cătălin; Rădulescu, Radu; Chifiriuc, Mariana Carmen

2016-06-01

In this study, we investigated the potential of MAPLE-deposited coatings mesoporous silica nanoparticles (MSNs) to release Zinforo (ceftarolinum fosmil) in biologically active form. The MSNs were prepared by using a classic procedure with cetyltrimethylammonium bromide as sacrificial template and tetraethylorthosilicate as the monomer. The Brunauer-Emmett-Teller (BET) and transmission electron microscopy (TEM) analyses revealed network-forming granules with diameters under 100 nm and an average pore diameter of 2.33 nm. The deposited films were characterized by SEM, TEM, XRD and IR. Microbiological analyses performed on ceftaroline-loaded films demonstrated that the antibiotic was released in an active form, decreasing the microbial adherence rate and colonization of the surface. Moreover, the in vitro and in vivo assays proved the excellent biodistribution and biocompatibility of the prepared systems. Our results suggest that the obtained bioactive coatings possess a significant potential for the design of drug delivery systems and antibacterial medical-use surfaces, with great applications in bone implantology.

Preparation and antibacterial properties of Ag@polydopamine/graphene oxide sheet nanocomposite

NASA Astrophysics Data System (ADS)

Zhou, Hao; Liu, Yunfang; Chi, Weidong; Yu, Changyuan; Yu, Yingjie

2013-10-01

Immobilization of silver nanoparticles (Ag NPs) on poly-dopamine (PDA) functionalized graphene oxide sheets (GOSs) were carried out by an easy in situ reduction method. The PDA layer was coated on the surface of the GOSs via the self-polymerization of dopamine under atmosphere condition. The PDA layer not only works as the chemisorption and reduction sites for silver ions to form Ag NPs but also stabilizes them. High-resolution transmission electron microscopy observation shows that the average size of the Ag NPs anchored on the PDA/GOS composite is about 2.8 nm. The inhibition zone diameter of the Ag@PDA/GOS nanocomposite is about 23.7 mm, whereas said diameter of the Ag NPs is only 18.5 mm. The minimum bactericidal concentration of the Ag@PDA/GOS nanocomposite is about 25 μg/ml that is only half of said concentration of the Ag NPs. The Ag@PDA/GOS nanocomposite exhibits an excellent antibacterial property.

Facile, one-pot synthesis, and antibacterial activity of mesoporous silica nanoparticles decorated with well-dispersed silver nanoparticles.

PubMed

Tian, Yue; Qi, Juanjuan; Zhang, Wei; Cai, Qiang; Jiang, Xingyu

2014-08-13

In this study, we exploit a facile, one-pot method to prepare MCM-41 type mesoporous silica nanoparticles decorated with silver nanoparticles (Ag-MSNs). Silver nanoparticles with diameter of 2-10 nm are highly dispersed in the framework of mesoporous silica nanoparticles. These Ag-MSNs possess an enhanced antibacterial effect against both Gram-positive and Gram-negative bacteria by preventing the aggregation of silver nanoparticles and continuously releasing silver ions for one month. The cytotoxicity assay indicates that the effective antibacterial concentration of Ag-MSNs shows little effect on human cells. This report describes an efficient and economical route to synthesize mesoporous silica nanoparticles with uniform silver nanoparticles, and these nanoparticles show promising applications as antibiotics.

Diameter control of vertically aligned carbon nanotubes using CoFe2O4 nanoparticle Langmuir-Blodgett films

NASA Astrophysics Data System (ADS)

Tamiya, Shuhei; Sato, Taiga; Kushida, Masahito

2018-03-01

Vertically aligned carbon nanotubes (VA-CNTs) are suggested for utilization as a new catalyst support of polymer electrolyte fuel cells (PEFCs). The independent control of the diameter and number density of VA-CNTs is essential for application in PEFCs. As the catalyst for VA-CNT growth, we fabricated CoFe2O4 nanoparticle (NP) films using the Langmuir-Blodgett (LB) technique. Using the LB technique, we were able to separately control the diameter and number density of VA-CNTs. The number density of VA-CNTs was changed by mixing with the filler moleculer, palmitic acid (C16). The VA-CNT diameter was changed by the adjusting the CoFe2O4 NP diameter. However, the heat-induced aggregation of CoFe2O4 NPs occurred in thermal chemical vapor deposition to synthesize VA-CNTs. Therefore, we examined how to minimize the effect of heat-induced aggregation of CoFe2O4 NPs. As a result, selection of the appropriate number density and diameter of CoFe2O4 NPs was found to be important for the control of VA-CNT diameter.

Radionuclide therapy using ¹³¹I-labeled anti-epidermal growth factor receptor-targeted nanoparticles suppresses cancer cell growth caused by EGFR overexpression.

PubMed

Li, Wei; Liu, Zhongyun; Li, Chengxia; Li, Ning; Fang, Lei; Chang, Jin; Tan, Jian

2016-03-01

Anti-epidermal growth factor receptor (EGFR)-targeted nanoparticles can be used to deliver a therapeutic and imaging agent to EGFR-overexpressing tumor cells. (131)I-labeled anti-EGFR nanoparticles derived from cetuximab were used as a tumor-targeting vehicle in radionuclide therapy. This paper describes the construction of the anti-EGFR nanoparticle EGFR-BSA-PCL. This nanoparticle was characterized for EGFR-targeted binding and cellular uptake in EGFR-overexpressing cancer cells by using flow cytometry and confocal microscopy. Anti-EGFR and non-targeted nanoparticles were labeled with (131)I using the chloramine-T method. Analyses of cytotoxicity and targeted cell killing with (131)I were performed using the MTT assay. The time-dependent cellular uptake of (131)I-labeled anti-EGFR nanoparticles proved the slow-release effects of nanoparticles. A radioiodine therapy study was also performed in mice. The EGFR-targeted nanoparticle EGFR-BSA-PCL and the non-targeted nanoparticle BSA-PCL were constructed; the effective diameters were approximately 100 nm. The results from flow cytometry and confocal microscopy revealed significant uptake of EGFR-BSA-PCL in EGFR-overexpressing tumor cells. Compared with EGFR-BSA-PCL, BSA-PCL could also bind to cells, but tumor cell retention was minimal and weak. In MTT assays, the EGFR-targeted radioactive nanoparticle (131)I-EGFR-BSA-PCL showed greater cytotoxicity and targeted cell killing than the non-targeted nanoparticle (131)I-BSA-PCL. The radioiodine uptake of both (131)I-labeled nanoparticles, (131)I-EGFR-BSA-PCL and (131)I-BSA-PCL, was rapid and reached maximal levels 4 h after incubation, but the (131)I uptake of (131)I-EGFR-BSA-PCL was higher than that of (131)I-BSA-PCL. On day 15, the average tumor volumes of the (131)I-EGFR-BSA-PCL and (131)I-BSA-PCL groups showed a slow growth relationship compared with that of the control group. The EGFR-targeted nanoparticle EGFR-BSA-PCL demonstrated superior cellular binding and uptake compared with those of the control BSA-PCL. The EGFR-targeted radioactive nanoparticle (131)I-EGFR-BSA-PCL exhibited favorable intracellular retention of (131)I. Radionuclide therapy using (131)I-EGFR-BSA-PCL, which showed excellent targeted cell killing, suppressed cancer cell growth caused by EGFR overexpression.

Use of Fe3O4 Nanoparticles for Enhancement of Biosensor Response to the Herbicide 2,4-Dichlorophenoxyacetic Acid

PubMed Central

Loh, Kee-Shyuan; Lee, Yook Heng; Musa, Ahmad; Salmah, Abdul Aziz; Zamri, Ishak

2008-01-01

Magnetic nanoparticles of Fe3O4 were synthesized and characterized using transmission electron microscopy and X-ray diffraction. The Fe3O4 nanoparticles were found to have an average diameter of 5.48 ±1.37 nm. An electrochemical biosensor based on immobilized alkaline phosphatase (ALP) and Fe3O4 nanoparticles was studied. The amperometric biosensor was based on the reaction of ALP with the substrate ascorbic acid 2-phosphate (AA2P). The incorporation of the Fe3O4 nanoparticles together with ALP into a sol gel/chitosan biosensor membrane has led to the enhancement of the biosensor response, with an improved linear response range to the substrate AA2P (5-120 μM) and increased sensitivity. Using the inhibition property of the ALP, the biosensor was applied to the determination of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). The use of Fe3O4 nanoparticles gives a two-fold improvement in the sensitivity towards 2,4-D, with a linear response range of 0.5-30 μgL-1. Exposure of the biosensor to other toxicants such as heavy metals demonstrated only slight interference from metals such as Hg2+, Cu2+, Ag2+ and Pb2+. The biosensor was shown to be useful for the determination of the herbicide 2, 4-D because good recovery of 95-100 percent was obtained, even though the analysis was performed in water samples with a complex matrix. Furthermore, the results from the analysis of 2,4-D in water samples using the biosensor correlated well with a HPLC method. PMID:27873839

Effect of Nanoencapsulated Vitamin B1 Derivative on Inhibition of Both Mycelial Growth and Spore Germination of Fusarium oxysporum f. sp. raphani

PubMed Central

Cho, Jeong Sub; Seo, Yong Chang; Yim, Tae Bin; Lee, Hyeon Yong

2013-01-01

Nanoencapsulation of thiamine dilauryl sulfate (TDS), a vitamin B1 derivative, was proved to effectively inhibit the spore germination of Fusarium oxysporum f. sp. raphani (F. oxysporum), as well as mycelial growth. The average diameter of nanoparticles was measured as 136 nm by being encapsulated with an edible encapsulant, lecithin, whose encapsulation efficiency was about 55% in containing 200 ppm of TDS concentration: the 100 ppm TDS nanoparticle solution showed a mycelial growth inhibition rate of 59%. These results were about similar or even better than the cases of treating 100 ppm of dazomet, a positive antifungal control (64%). Moreover, kinetic analysis of inhibiting spore germination were estimated as 6.6% reduction of spore germination rates after 24 h treatment, which were 3.3% similar to the case of treating 100 ppm of a positive control (dazomet) for the same treatment time. It was also found that TDS itself could work as an antifungal agent by inhibiting both mycelial growth and spore germination, even though its efficacy was lower than those of nanoparticles. Nanoparticles especially played a more efficient role in limiting the spore germination, due to their easy penetration into hard cell membranes and long resident time on the surface of the spore shell walls. In this work, it was first demonstrated that the nanoparticle of TDS not a harmful chemical can control the growth of F. oxysporum by using a lower dosage than commercial herbicides, as well as the inhibiting mechanism of the TDS. However, field trials of the TDS nanoparticles encapsulated with lecithin should be further studied to be effectively used for field applications. PMID:23429270

Tailoring sub-micron PLGA particle release profiles via centrifugal fractioning

PubMed Central

Dutta, Dipankar; Salifu, Mariama; Sirianni, Rachael W.; Stabenfeldt, Sarah E.

2016-01-01

Poly(D,L-lactic-co-glycolic) acid (PLGA)-based submicron particles are uniquely posed to overcome limitations of conventional drug delivery systems. However, tailoring cargo/payload release profiles from PLGA micro/nanoparticles typically requires optimization of the multi-parameter formulation, where small changes may cause drastic shifts in the resulting release profiles. In this study, we aimed to establish whether refining the average diameter of submicron particle populations after formulation alters protein release profiles. PLGA particles were first produced via double emulsion-solvent evaporation method to encapsulate bovine serum albumin. Particles were then subjected to centrifugal fractioning protocols varying in both spin time and force to determine encapsulation efficiency and release profile of differently sized populations that originated from a single batch. We found the average particle diameter was related to marked alterations in encapsulation efficiencies (range: 36.4–49.4%), burst release (range: 15.8–49.1%), and time for total cargo release (range: 38–78 days). Our data corroborate previous reports relating PLGA particle size with such release characteristics, however, this is the first study, to our knowledge, to directly compare particle population size while holding all formulation parameters constant. In summary, centrifugal fractioning to selectively control the population distribution of sub-micron PLGA particles represents a feasible tool to tailor release characteristics. PMID:26517011

A facile approach for cupric ion detection in aqueous media using polyethyleneimine/PMMA core-shell fluorescent nanoparticles

NASA Astrophysics Data System (ADS)

Chen, Jian; Zeng, Fang; Wu, Shuizhu; Su, Junhua; Zhao, Jianqing; Tong, Zhen

2009-09-01

A facile approach was developed to produce a dye-doped core-shell nanoparticle chemosensor for detecting Cu2+ in aqueous media. The core-shell nanoparticle sensor was prepared by a one-step emulsifier-free polymerization, followed by the doping of the fluorescent dye Nile red (9-diethylamino- 5H-benzo[alpha] phenoxazine-5-one, NR) into the particles. For the nanoparticles, the hydrophilic polyethyleneimine (PEI) chain segments serve as the shell and the hydrophobic polymethyl methacrylate (PMMA) constitutes the core of the nanoparticles. The non-toxic and biocompatible PEI chain segments on the nanoparticle surface exhibit a high affinity for Cu2+ ions in aqueous media, and the quenching of the NR fluorescence is observed upon binding of Cu2+ ions. This makes the core-shell nanoparticle system a water-dispersible chemosensor for Cu2+ ion detection. The quenching of fluorescence arises through intraparticle energy transfer (FRET) from the dye in the hydrophobic PMMA core to the Cu2+/PEI complexes on the nanoparticle surface. The energy transfer efficiency for PEI/PMMA particles with different diameters was determined, and it is found that the smaller nanoparticle sample exhibits higher quenching efficiency, and the limit for Cu2+ detection is 1 µM for a nanoparticle sample with a diameter of ~30 nm. The response of the fluorescent nanoparticle towards different metal ions was investigated and the nanoparticle chemosensor displays high selectivity and antidisturbance for the Cu2+ ion among the metal ions examined (Na+, K+, Mg2+, Ca2+, Zn2+, Hg2+, Mn2+, Fe2+, Ni2+, Co2+ and Pb2+). This emulsifier-free, biocompatible and sensitive fluorescent nanoparticle sensor may find applications in cupric ion detection in the biological and environmental areas.

A facile approach for cupric ion detection in aqueous media using polyethyleneimine/PMMA core-shell fluorescent nanoparticles.

PubMed

Chen, Jian; Zeng, Fang; Wu, Shuizhu; Su, Junhua; Zhao, Jianqing; Tong, Zhen

2009-09-09

A facile approach was developed to produce a dye-doped core-shell nanoparticle chemosensor for detecting Cu(2+) in aqueous media. The core-shell nanoparticle sensor was prepared by a one-step emulsifier-free polymerization, followed by the doping of the fluorescent dye Nile red (9-diethylamino- 5H-benzo[alpha] phenoxazine-5-one, NR) into the particles. For the nanoparticles, the hydrophilic polyethyleneimine (PEI) chain segments serve as the shell and the hydrophobic polymethyl methacrylate (PMMA) constitutes the core of the nanoparticles. The non-toxic and biocompatible PEI chain segments on the nanoparticle surface exhibit a high affinity for Cu(2+) ions in aqueous media, and the quenching of the NR fluorescence is observed upon binding of Cu(2+) ions. This makes the core-shell nanoparticle system a water-dispersible chemosensor for Cu(2+) ion detection. The quenching of fluorescence arises through intraparticle energy transfer (FRET) from the dye in the hydrophobic PMMA core to the Cu(2+)/PEI complexes on the nanoparticle surface. The energy transfer efficiency for PEI/PMMA particles with different diameters was determined, and it is found that the smaller nanoparticle sample exhibits higher quenching efficiency, and the limit for Cu(2+) detection is 1 microM for a nanoparticle sample with a diameter of approximately 30 nm. The response of the fluorescent nanoparticle towards different metal ions was investigated and the nanoparticle chemosensor displays high selectivity and antidisturbance for the Cu(2+) ion among the metal ions examined (Na(+), K(+), Mg(2+), Ca(2+), Zn(2+), Hg(2+), Mn(2+), Fe(2+), Ni(2+), Co(2+) and Pb(2+)). This emulsifier-free, biocompatible and sensitive fluorescent nanoparticle sensor may find applications in cupric ion detection in the biological and environmental areas.

Facile Large-scale synthesis of stable CuO nanoparticles

NASA Astrophysics Data System (ADS)

Nazari, P.; Abdollahi-Nejand, B.; Eskandari, M.; Kohnehpoushi, S.

2018-04-01

In this work, a novel approach in synthesizing the CuO nanoparticles was introduced. A sequential corrosion and detaching was proposed in the growth and dispersion of CuO nanoparticles in the optimum pH value of eight. The produced CuO nanoparticles showed six nm (±2 nm) in diameter and spherical feather with a high crystallinity and uniformity in size. In this method, a large-scale production of CuO nanoparticles (120 grams in an experimental batch) from Cu micro-particles was achieved which may met the market criteria for large-scale production of CuO nanoparticles.

Cytoprotective nanoparticles by conjugation of a polyhis tagged annexin V to a nanoparticle drug.

PubMed

Chen, Howard H; Yuan, Hushan; Cho, Hoonsung; Sosnovik, David E; Josephson, Lee

2015-02-14

We synthesized a cytoprotective magnetic nanoparticle by reacting a maleimide functionalized Feraheme (FH) with a disulfide linked dimer of a polyhis tagged annexin V. Following reductive cleavage of disulfide, the resulting annexin-nanoparticle (diameter = 28.0 ± 2.0 nm by laser light scattering, 7.6 annexin's/nanoparticle) was cytoprotective to cells subjected to plasma membrane disrupting chemotherapeutic or mechanical stresses, and significantly more protective than the starting annexin V. Annexin-nanoparticles provide an approach to the design of nanomaterials which antagonize the plasma membrane permeability characteristic of necrosis and which may have applications as cytoprotective agents.

Preparation and characterization of APTES modified magnetic MMT capable of using as anisotropic nanoparticles

NASA Astrophysics Data System (ADS)

Li, Yingjun; Chen, Hua; Wu, Jie; He, Qin; Li, Yintao; Yang, Wenbin; Zhou, Yuanlin

2018-07-01

Montmorillonite (MMT) based anisotropic magnetic nanoparticles (Fe3O4/APTES/MMT) with high anisotropy and reliable magnetism were prepared by using Fe3O4 as magnetic nanoparticles and γ-aminopropyltriethoxysilane (ATPES) as modifier. The characterization indicated that the interactions between Fe3O4 nanoparticles and MMT in Fe3O4/APTES/MMT were stronger than that of directly deposited on to MMT (Fe3O4-MMT) because APTES was chemically bonded to both Fe3O4 and MMT. Fe3O4/APTES/MMT had a greater Ms value (25.16 emu/g) than Fe3O4-MMT (23.71 emu/g). Also, ultrasonication was used to test the interactions between Fe3O4 and MMT. With 30 min of ultrasonication, the amount of Fe3O4 nanoparticles on the surface of Fe3O4/APTES/MMT was more than that of Fe3O4-MMT, and Fe3O4/APTES/MMT had a faster magnetic response to a magnetic field than that of Fe3O4-MMT because of enhanced interactions between Fe3O4 and MMT in Fe3O4/APTES/MMT. In addition, Fe3O4 nanoparticles were densely immobilized onto Fe3O4/APTES/MMT with a smaller average diameter, and the distribution of Fe3O4 nanoparticles on the surface of MMT was more uniform than that of Fe3O4-MMT. Fe3O4/APTES/MMT possessed stable and high magnetism, in ease of orientation and recycling in the magnetic field, and this makes it a promising candidate as anisotropic nanoparticles for use in preparing anisotropic inorganic/polymer composites and anisotropic adsorbents used in wastewater treatment. Finally, the mechanism of ATPES-modified magnetic MMT was investigated.

Metal matrix-metal nanoparticle composites with tunable melting temperature and high thermal conductivity for phase-change thermal storage.

PubMed

Liu, Minglu; Ma, Yuanyu; Wu, Hsinwei; Wang, Robert Y

2015-02-24

Phase-change materials (PCMs) are of broad interest for thermal storage and management applications. For energy-dense storage with fast thermal charging/discharging rates, a PCM should have a suitable melting temperature, large enthalpy of fusion, and high thermal conductivity. To simultaneously accomplish these traits, we custom design nanocomposites consisting of phase-change Bi nanoparticles embedded in an Ag matrix. We precisely control nanoparticle size, shape, and volume fraction in the composite by separating the nanoparticle synthesis and nanocomposite formation steps. We demonstrate a 50-100% thermal energy density improvement relative to common organic PCMs with equivalent volume fraction. We also tune the melting temperature from 236-252 °C by varying nanoparticle diameter from 8.1-14.9 nm. Importantly, the silver matrix successfully prevents nanoparticle coalescence, and no melting changes are observed during 100 melt-freeze cycles. The nanocomposite's Ag matrix also leads to very high thermal conductivities. For example, the thermal conductivity of a composite with a 10% volume fraction of 13 nm Bi nanoparticles is 128 ± 23 W/m-K, which is several orders of magnitude higher than typical thermal storage materials. We complement these measurements with calculations using a modified effective medium approximation for nanoscale thermal transport. These calculations predict that the thermal conductivity of composites with 13 nm Bi nanoparticles varies from 142 to 47 W/m-K as the nanoparticle volume fraction changes from 10 to 35%. Larger nanoparticle diameters and/or smaller nanoparticle volume fractions lead to larger thermal conductivities.

Structural phase transitions in SrTiO 3 nanoparticles

DOE PAGES

Zhang, Han; Liu, Sizhan; Scofield, Megan E.; ...

2017-08-04

We present that pressure dependent structural measurements on monodispersed nanoscale SrTiO 3 samples with average diameters of 10 to ~80 nm were conducted to enhance the understanding of the structural phase diagram of nanoscale SrTiO 3. A robust pressure independent polar structure was found in the 10 nm sample for pressures up to 13 GPa, while a size dependent cubic to tetragonal transition occurs (at P = P c) for larger particle sizes. In conclusion, the results suggest that the growth of ~10 nm STO particles on substrates with significant lattice mismatch may maintain a polar state for a largemore » range of strain values, possibly enabling device use.« less

Facile Synthesis of Uniform Virus-like Mesoporous Silica Nanoparticles for Enhanced Cellular Internalization

PubMed Central

2017-01-01

The low-efficiency cellular uptake property of current nanoparticles greatly restricts their application in the biomedical field. Herein, we demonstrate that novel virus-like mesoporous silica nanoparticles can easily be synthesized, showing greatly superior cellular uptake property. The unique virus-like mesoporous silica nanoparticles with a spiky tubular rough surface have been successfully synthesized via a novel single-micelle epitaxial growth approach in a low-concentration-surfactant oil/water biphase system. The virus-like nanoparticles’ rough surface morphology results mainly from the mesoporous silica nanotubes spontaneously grown via an epitaxial growth process. The obtained nanoparticles show uniform particle size and excellent monodispersity. The structural parameters of the nanoparticles can be well tuned with controllable core diameter (∼60–160 nm), tubular length (∼6–70 nm), and outer diameter (∼6–10 nm). Thanks to the biomimetic morphology, the virus-like nanoparticles show greatly superior cellular uptake property (invading living cells in large quantities within few minutes, <5 min), unique internalization pathways, and extended blood circulation duration (t1/2 = 2.16 h), which is much longer than that of conventional mesoporous silica nanoparticles (0.45 h). Furthermore, our epitaxial growth strategy can be applied to fabricate various virus-like mesoporous core–shell structures, paving the way toward designed synthesis of virus-like nanocomposites for biomedicine applications. PMID:28852697

When Anatase Nanoparticles Become Bulklike: Properties of Realistic TiO2 Nanoparticles in the 1-6 nm Size Range from All Electron Relativistic Density Functional Theory Based Calculations.

PubMed

Lamiel-Garcia, Oriol; Ko, Kyoung Chul; Lee, Jin Yong; Bromley, Stefan T; Illas, Francesc

2017-04-11

All electron relativistic density functional theory (DFT) based calculations using numerical atom-centered orbitals have been carried out to explore the relative stability, atomic, and electronic structure of a series of stoichiometric TiO 2 anatase nanoparticles explicitly containing up to 1365 atoms as a function of size and morphology. The nanoparticles under scrutiny exhibit octahedral or truncated octahedral structures and span the 1-6 nm diameter size range. Initial structures were obtained using the Wulff construction, thus exhibiting the most stable (101) and (001) anatase surfaces. Final structures were obtained from geometry optimization with full relaxation of all structural parameters using both generalized gradient approximation (GGA) and hybrid density functionals. Results show that, for nanoparticles of a similar size, octahedral and truncated octahedral morphologies have comparable energetic stabilities. The electronic structure properties exhibit a clear trend converging to the bulk values as the size of the nanoparticles increases but with a marked influence of the density functional employed. Our results suggest that electronic structure properties, and hence reactivity, for the largest anatase nanoparticles considered in this study will be similar to those exhibited by even larger mesoscale particles or by bulk systems. Finally, we present compelling evidence that anatase nanoparticles become effectively bulklike when reaching a size of ∼20 nm diameter.

Fabrication of ZnS nanoparticle chains on a protein template

PubMed Central

Hulleman, J.; Kim, S. M.; Tumkur, T.; Rochet, J.-C.; Stach, E.; Stanciu, L.

2011-01-01

In the present study, we have exploited the properties of a fibrillar protein for the template synthesis of zinc sulfide (ZnS) nanoparticle chains. The diameter of the ZnS nanoparticle chains was tuned in range of ~30 to ~165 nm by varying the process variables. The nanoparticle chains were characterized by field emission scanning electron microscopy, UV–Visible spectroscopy, transmission electron microscopy, electron energy loss spectroscopy, and high-resolution transmission electron microscopy. The effect of incubation temperature on the morphology of the nanoparticle chains was also studied. PMID:21804765

Formation of polymer nanoparticles by UV pulsed laser ablation of poly (bisphenol A carbonate) in liquid environment

NASA Astrophysics Data System (ADS)

Martínez-Tong, Daniel E.; Sanz, Mikel; Ezquerra, Tiberio A.; Nogales, Aurora; Marco, José F.; Castillejo, Marta; Rebollar, Esther

2017-10-01

Suspensions of poly(bisphenol A carbonate) (PBAC) nanoparticles of varying size and shape have been produced by ablation of a PBAC target in liquid media with the fourth harmonic of a Q-switched Nd:YAG laser (wavelength 266 nm, full width at half maximum 4 ns, repetition rate 10 Hz). The polymer target was placed at the bottom of a rotating glass vessel filled with around a 10 mm column of liquid. Laser ablation in water leads to spherical nanoparticles with diameters of several tens of nanometers for fluences close to 1 J/cm2. Ablation at lower fluences, around 0.1 J/cm2, results in the production of nanoparticles of smaller diameters and also of non-spherical nanoparticles. Additional irradiations at the fluence of 0.1 J/cm2 were performed in several liquid media with different properties, in terms of density, viscosity, thermal conductivity, boiling temperature, isothermal compressibility and polarity. The different size distributions observed were related to the thermal conductivity of the systems, while their viscosity seems to be responsible for the development of nanostructures with different morphologies.

Characterization of nZVI mobility in a field scale test.

PubMed

Kocur, Chris M; Chowdhury, Ahmed I; Sakulchaicharoen, Nataphan; Boparai, Hardiljeet K; Weber, Kela P; Sharma, Prabhakar; Krol, Magdalena M; Austrins, Leanne; Peace, Christopher; Sleep, Brent E; O'Carroll, Denis M

2014-01-01

Nanoscale zerovalent iron (nZVI) particles were injected into a contaminated sandy subsurface area in Sarnia, Ontario. The nZVI was synthesized on site, creating a slurry of 1 g/L nanoparticles using the chemical precipitation method with sodium borohydride (NaBH4) as the reductant in the presence of 0.8% wt. sodium carboxymethylcellulose (CMC) polymer to form a stable suspension. Individual nZVI particles formed during synthesis had a transmission electron microscopy (TEM) quantified particle size of 86.0 nm and dynamic light scattering (DLS) quantified hydrodynamic diameter for the CMC and nZVI of 624.8 nm. The nZVI was delivered to the subsurface via gravity injection. Peak normalized total Fe breakthrough of 71% was observed 1m from the injection well and remained above 50% for the 24 h injection period. Samples collected from a monitoring well 1 m from the injection contained nanoparticles with TEM-measured particle diameter of 80.2 nm and hydrodynamic diameter of 562.9 nm. No morphological changes were discernible between the injected nanoparticles and nanoparticles recovered from the monitoring well. Energy dispersive X-ray spectroscopy (EDS) was used to confirm the elemental composition of the iron nanoparticles sampled from the downstream monitoring well, verifying the successful transport of nZVI particles. This study suggests that CMC stabilized nZVI can be transported at least 1 m to the contaminated source zone at significant Fe(0) concentrations for reaction with target contaminants.

Biodistribution of a High Dose of Diamond, Graphite, and Graphene Oxide Nanoparticles After Multiple Intraperitoneal Injections in Rats.

PubMed

Kurantowicz, Natalia; Strojny, Barbara; Sawosz, Ewa; Jaworski, Sławomir; Kutwin, Marta; Grodzik, Marta; Wierzbicki, Mateusz; Lipińska, Ludwika; Mitura, Katarzyna; Chwalibog, André

2015-12-01

Carbon nanoparticles have recently drawn intense attention in biomedical applications. Hence, there is a need for further in vivo investigations of their biocompatibility and biodistribution via various exposure routes. We hypothesized that intraperitoneally injected diamond, graphite, and graphene oxide nanoparticles may have different biodistribution and exert different effects on the intact organism. Forty Wistar rats were divided into four groups: the control and treated with nanoparticles by intraperitoneal injection (4 mg of nanoparticles/kg body weight) eight times during the 4-week period. Blood was collected for evaluation of blood morphology and biochemistry parameters. Photographs of the general appearance of each rat's interior were taken immediately after sacrifice. The organs were excised and their macroscopic structure was visualized using a stereomicroscope. The nanoparticles were retained in the body, mostly as agglomerates. The largest agglomerates (up to 10 mm in diameter) were seen in the proximity of the injection place in the stomach serous membrane, between the connective tissues of the abdominal skin, muscles, and peritoneum. Numerous smaller, spherical-shaped aggregates (diameter around 2 mm) were lodged among the mesentery. Moreover, in the connective and lipid tissue in the proximity of the liver and spleen serosa, small aggregates of graphite and graphene oxide nanoparticles were observed. However, all tested nanoparticles did not affect health and growth of rats. The nanoparticles had no toxic effects on blood parameters and growth of rats, suggesting their potential applicability as remedies or in drug delivery systems.

Characterizing the Role of Nanoparticle Design on Tumor Transport and Stability in the Extracellular Environment

NASA Astrophysics Data System (ADS)

Albanese, Alexandre

Nanotechnology has emerged as an exciting strategy for the delivery of diagnostic and therapeutic agents into established tumors. Advancements in nanomaterial synthesis have generated an extensive number of nanoparticle designs made from different materials. Unfortunately, it remains impossible to predict a design's effectiveness for in vivo tumor accumulation. Little is known about how a nanoparticle's morphology and surface chemistry affect its interactions with cells and proteins inside the tumor tissue. This thesis focuses on the development of in vitro experimental tools to evaluate how nanoparticle design affects transport in a three-dimensional tumor tissue and stability in the tumor microenvironment. Nanoparticle transport was evaluated using a novel 'tumor-on-a-chip' system where multicellular tumor spheroids were immobilized in a microfluidic channel. This setup created a three-dimensional tumor environment displaying physiological cell density, extracellular matrix organization, and interstitial flow rates. The tumor-on-a-chip demonstrated that accumulation of nanoparticles was limited to diameters below 110 nm and was improved by receptor targeting. Nanoparticle stability in the tumor microenvironment was evaluated using media isolated from different tumor cell lines. Nanoparticle diameter and surface chemistry were important determinants of stability in cancer cell-conditioned media. Small nanoparticles with unstable surface chemistries adsorbed cellular proteins on their surface and were prone to aggregation. Nanoparticle aggregation altered cellular interactions leading to changes in cell uptake. Using a novel technique to generate different aggregate sizes possessing a uniform surface composition, it was determined that aggregation can change receptor affinity, cell internalization mechanisms and sub-cellular sequestration patterns. Data from this thesis characterize the behavior of nanoparticles within modeled tumor environments and provide some preliminary design guidelines for maximizing nanoparticle tumor accumulation. This work highlights the importance of characterizing nano-bio interactions for engineering successful nanomaterial-based delivery systems.

Synthesis of composite magnetic nanoparticles Fe3O4 with alendronate for osteoporosis treatment

PubMed Central

Lee, Ming-Song; Su, Chao-Ming; Yeh, Jih-Chao; Wu, Pei-Ru; Tsai, Tien-Yao; Lou, Shyh-Liang

2016-01-01

Osteoporosis is a result of imbalance between bone formation by osteoblasts and resorption by osteoclasts (OCs). In the present study, we investigated the potential of limiting the aggravation of osteoporosis by reducing the activity of OCs through thermolysis. The proposed method is to synthesize bisphosphonate (Bis)-conjugated iron (II, III) oxide (Fe3O4) nanoparticles and incorporate them into OCs. The cells should be subsequently exposed to radiofrequency (RF) to induce thermolysis. In this study, particles of Fe3O4 were first synthesized by chemical co-precipitation and then coated with dextran (Dex). The Dex/Fe3O4 particles were then conjugated with Bis to form Bis/Dex/Fe3O4. Transmission electron microscopy revealed that the average diameter of the Bis/Dex/Fe3O4 particles was ~20 nm. All three kinds of nanoparticles were found to have cubic inverse spinel structure of Fe3O4 by the X-ray diffraction analysis. Fourier transform infrared spectroscopy confirmed that the Dex/Fe3O4 and Bis/Dex/Fe3O4 nanoparticles possessed their respective Dex and Bis functional groups, while a superconducting quantum interference device magnetometer measured the magnetic moment to be 24.5 emu. In addition, the Bis/Dex/Fe3O4 nanoparticles were fully dispersed in double-distilled water. Osteoblasts and OCs were individually cultured with the nanoparticles, and an MTT assay revealed that they were non-cytotoxic. An RF system (42 kHz and 450 A) was used to raise the temperature of the nanoparticles for 20 minutes, and the thermal effect was found to be sufficient to destroy OCs. Furthermore, in vivo studies verified that nanoparticles were indeed magnetic resonance imaging contrast agents and that they accumulated after being injected into the body of rats. In conclusion, we developed a water-dispersible magnetic nanoparticle that had RF-induced thermogenic properties, and the results indicated that the Bis/Dex/Fe3O4 nanoparticle had the potential for controlling osteoporosis. PMID:27695319

Size-dependent phase diagrams of metallic alloys: A Monte Carlo simulation study on order–disorder transitions in Pt–Rh nanoparticles

PubMed Central

Stahl, Christian; Albe, Karsten

2012-01-01

Summary Nanoparticles of Pt–Rh were studied by means of lattice-based Monte Carlo simulations with respect to the stability of ordered D022- and 40-phases as a function of particle size and composition. By thermodynamic integration in the semi-grand canonical ensemble, phase diagrams for particles with a diameter of 7.8 nm, 4.3 nm and 3.1 nm were obtained. Size-dependent trends such as the lowering of the critical ordering temperature, the broadening of the compositional stability range of the ordered phases, and the narrowing of the two-phase regions were observed and discussed in the context of complete size-dependent nanoparticle phase diagrams. In addition, an ordered surface phase emerges at low temperatures and low platinum concentration. A decrease of platinum surface segregation with increasing global platinum concentration was observed, when a second, ordered phase is formed inside the core of the particle. The order–disorder transitions were analyzed in terms of the Warren–Cowley short-range order parameters. Concentration-averaged short-range order parameters were used to remove the surface segregation bias of the conventional short-range order parameters. Using this procedure, it was shown that the short-range order in the particles at high temperatures is bulk-like. PMID:22428091

Colloidal stability of carbonate-coated silver nanoparticles in synthetic and natural freshwater.

PubMed

Piccapietra, Flavio; Sigg, Laura; Behra, Renata

2012-01-17

To gain important information on fate, mobility, and bioavailability of silver nanoparticles (AgNP) in aquatic systems, the influence of pH, ionic strength, and humic substances on the stability of carbonate-coated AgNP (average diameter 29 nm) was systematically investigated in 10 mM carbonate and 10 mM MOPS buffer, and in filtered natural freshwater. Changes in the physicochemical properties of AgNP were measured using nanoparticle tracking analysis, dynamic light scattering, and ultraviolet-visible spectroscopy. According to the pH-dependent carbonate speciation, below pH 4 the negatively charged surface of AgNP became positive and increased agglomeration was observed. Electrolyte concentrations above 2 mM Ca(2+) and 100 mM Na(+) enhanced AgNP agglomeration in the synthetic media. In the considered concentration range of humic substances, no relevant changes in the AgNP agglomeration state were measured. Agglomeration of AgNP exposed in filtered natural freshwater was observed to be primarily controlled by the electrolyte type and concentration. Moreover, agglomerated AgNP were still detected after 7 days of exposure. Consequently, slow sedimentation and high mobility of agglomerated AgNP could be expected under the considered natural conditions. A critical evaluation of the different methods used is presented as well.

Synthesis of colloidal silver iron oxide nanoparticles--study of their optical and magnetic behavior.

PubMed

Kumar, Anil; Singhal, Aditi

2009-07-22

Silver iron oxide nanoparticles of fairly small size (average diameter approximately 1 nm) with narrow size distribution have been synthesized by the interaction of colloidal beta- Fe2O3 and silver nanoparticles. The surface morphology and size of these particles have been analyzed by using atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). Their structural analysis has been carried out by employing x-ray diffraction (XRD), selected-area electron diffraction (SAED), optical and infrared (IR) spectroscopic techniques. The ageing of these particles exhibits the formation of self-assembly, possibly involving weak supramolecular interactions between Ag(I)O4 and Fe(III)O4 species. These particles display the onset of absorption in the near-infrared region and have higher absorption coefficient in the visible range compared to that of its precursors. Magnetic measurements reveal an interesting transition in their magnetic behavior from diamagnetic to superparamagnetic. The magnetic moment of these particles attains a limiting value of about 0.19 emu cm(-2), which is more than two times higher than that of colloidal beta- Fe2O3. With enhanced optical and magnetic properties, this system is suggested to have possible applications in optoelectronic and magnetic devices.

Chitosan film loaded with silver nanoparticles-sorbent for solid phase extraction of Al(III), Cd(II), Cu(II), Co(II), Fe(III), Ni(II), Pb(II) and Zn(II).

PubMed

Djerahov, Lubomir; Vasileva, Penka; Karadjova, Irina; Kurakalva, Rama Mohan; Aradhi, Keshav Krishna

2016-08-20

The present study describes the ecofriendly method for the preparation of chitosan film loaded with silver nanoparticles (CS-AgNPs) and application of this film as efficient sorbent for separation and enrichment of Al(III), Cd(II), Cu(II), Co(II), Fe(III), Ni(II), Pb(II) and Zn(II). The stable CS-AgNPs colloid was prepared by dispersing the AgNPs sol in chitosan solution at appropriate ratio and further used to obtain a cast film with very good stability under storage and good mechanical strength for easy handling in aqueous medium. The incorporation of AgNPs in the structure of CS film and interaction between the polymer matrix and nanoparticles were confirmed by UV-vis and FTIR spectroscopy. The homogeneously embedded AgNPs (average diameter 29nm, TEM analysis) were clearly observed throughout the film by SEM. The CS-AgNPs nanocomposite film shows high sorption activity toward trace metals under optimized chemical conditions. The results suggest that the CS-AgNPs nanocomposite film can be feasibly used as a novel sorbent material for solid-phase extraction of metal pollutants from surface waters. Copyright © 2016 Elsevier Ltd. All rights reserved.

Aptamer conjugated silver nanoparticles for the detection of interleukin 6

NASA Astrophysics Data System (ADS)

Locke, Andrea K.; Norwood, Nicole; Marks, Haley L.; Schechinger, Monika; Jackson, George W.; Graham, Duncan; Coté, Gerard L.

2016-03-01

The controlled assembly of plasmonic nanoparticles by a molecular binding event has emerged as a simple yet sensitive methodology for protein detection. Metallic nanoparticles (NPs) coated with functionalized aptamers can be utilized as biosensors by monitoring changes in particle optical properties, such as the LSPR shift and enhancement of the SERS spectra, in the presence of a target protein. Herein we test this method using two modified aptamers selected for the protein biomarker interleukin 6, an indicator of the dengue fever virus and other diseases including certain types of cancers, diabetes, and even arthritis. IL6 works by inducing an immunological response within the body that can be either anti-inflammatory or pro-inflammatory. The results show that the average hydrodynamic diameter of the NPs as measured by Dynamic Light Scattering was ~42 nm. After conjugation of the aptamers, the peak absorbance of the AgNPs shifted from 404 to 408 nm indicating a surface modification of the NPs due to the presence of the aptamer. Lastly, preliminary results were obtained showing an increase in SERS intensity occurs when the IL-6 protein was introduced to the conjugate solution but the assay will still need to be optimized in order for it to be able to monitor varying concentration changes within and across the desired range.

Design and characterization of plasmids encoding antigenic peptides of Aha1 from Aeromonas hydrophila as prospective fish vaccines.

PubMed

Rauta, Pradipta R; Nayak, Bismita; Monteiro, Gabriel A; Mateus, Marília

2017-01-10

The current investigation aimed at designing DNA vaccines against Aeromonas hydrophila infections. The DNA vaccine candidates were designed to express two antigenic outer membrane protein (Aha1) peptides and to be delivered by a nanoparticle-based delivery system. Gene sequences of conserved regions of antigenic Aha1 [aha1(211-381), aha1(211-381)opt, aha1(703-999) and aha1(703-999)opt] were cloned into pVAX-GFP expression vector. The selected DNA vaccine candidates were purified from E. coli DH5α and transfected into Chinese hamster ovary cells. The expression of the antigenic peptides was measured in cells along post-transfection time, through the fluorescence intensity of the reporter GFP. The lipofection efficiency of aha-pVAX-GFP was highest after 24h incubation. Formulated PLGA-chitosan nanoparticle/plasmid DNA complexes were characterized in terms of size, size distribution and zeta potential. Nanocomplexes with average diameters in the range of 150-170nm transfected in a similar fashion into CHO cells confirmed transfection efficiency comparable to that of lipofection. DNA entrapment and further DNase digestion assays demonstrated ability for pDNA protection by the nanoparticles against enzymatic digestion. Copyright © 2016 Elsevier B.V. All rights reserved.

Enhancing the Antibacterial Activity of Light-Activated Surfaces Containing Crystal Violet and ZnO Nanoparticles: Investigation of Nanoparticle Size, Capping Ligand, and Dopants.

PubMed

Sehmi, Sandeep K; Noimark, Sacha; Pike, Sebastian D; Bear, Joseph C; Peveler, William J; Williams, Charlotte K; Shaffer, Milo S P; Allan, Elaine; Parkin, Ivan P; MacRobert, Alexander J

2016-09-30

Healthcare-associated infections pose a serious risk for patients, staff, and visitors and are a severe burden on the National Health Service, costing at least £1 billion annually. Antimicrobial surfaces significantly contribute toward reducing the incidence of infections as they prevent bacterial adhesion and cause bacterial cell death. Using a simple, easily upscalable swell-encapsulation-shrink method, novel antimicrobial surfaces have been developed by incorporating metal oxide nanoparticles (NPs) and crystal violet (CV) dye into medical-grade polyurethane sheets. This study compares the bactericidal effects of polyurethane incorporating ZnO, Mg-doped ZnO, and MgO. All metal oxide NPs are well defined, with average diameters ranging from 2 to 18 nm. These materials demonstrate potent bactericidal activity when tested against clinically relevant bacteria such as Escherichia coli and Staphylococcus aureus . Additionally, these composites are tested against an epidemic strain of methicillin-resistant Staphylococcus aureus (MRSA) that is rife in hospitals throughout the UK. Furthermore, we have tested these materials using a low light intensity (∼500 lx), similar to that present in many clinical environments. The highest activity is achieved from polymer composites incorporating CV and ∼3 nm ZnO NPs, and the different performances of the metal oxides have been discussed.

Infrared thermometry study of nanofluid pool boiling phenomena

PubMed Central

2011-01-01

Infrared thermometry was used to obtain first-of-a-kind, time- and space-resolved data for pool boiling phenomena in water-based nanofluids with diamond and silica nanoparticles at low concentration (<0.1 vol.%). In addition to macroscopic parameters like the average heat transfer coefficient and critical heat flux [CHF] value, more fundamental parameters such as the bubble departure diameter and frequency, growth and wait times, and nucleation site density [NSD] were directly measured for a thin, resistively heated, indium-tin-oxide surface deposited onto a sapphire substrate. Consistent with other nanofluid studies, the nanoparticles caused deterioration in the nucleate boiling heat transfer (by as much as 50%) and an increase in the CHF (by as much as 100%). The bubble departure frequency and NSD were found to be lower in nanofluids compared with water for the same wall superheat. Furthermore, it was found that a porous layer of nanoparticles built up on the heater surface during nucleate boiling, which improved surface wettability compared with the water-boiled surfaces. Using the prevalent nucleate boiling models, it was possible to correlate this improved surface wettability to the experimentally observed reductions in the bubble departure frequency, NSD, and ultimately to the deterioration in the nucleate boiling heat transfer and the CHF enhancement. PMID:21711754

Enhancing the Antibacterial Activity of Light-Activated Surfaces Containing Crystal Violet and ZnO Nanoparticles: Investigation of Nanoparticle Size, Capping Ligand, and Dopants

PubMed Central

2016-01-01

Healthcare-associated infections pose a serious risk for patients, staff, and visitors and are a severe burden on the National Health Service, costing at least £1 billion annually. Antimicrobial surfaces significantly contribute toward reducing the incidence of infections as they prevent bacterial adhesion and cause bacterial cell death. Using a simple, easily upscalable swell–encapsulation–shrink method, novel antimicrobial surfaces have been developed by incorporating metal oxide nanoparticles (NPs) and crystal violet (CV) dye into medical-grade polyurethane sheets. This study compares the bactericidal effects of polyurethane incorporating ZnO, Mg-doped ZnO, and MgO. All metal oxide NPs are well defined, with average diameters ranging from 2 to 18 nm. These materials demonstrate potent bactericidal activity when tested against clinically relevant bacteria such as Escherichia coli and Staphylococcus aureus. Additionally, these composites are tested against an epidemic strain of methicillin-resistant Staphylococcus aureus (MRSA) that is rife in hospitals throughout the UK. Furthermore, we have tested these materials using a low light intensity (∼500 lx), similar to that present in many clinical environments. The highest activity is achieved from polymer composites incorporating CV and ∼3 nm ZnO NPs, and the different performances of the metal oxides have been discussed. PMID:27840856

Amine functional magnetic nanoparticles via waterborne thiol-ene suspension photopolymerization for antibody immobilization.

PubMed

Muhsir, Pelin; Çakmakçi, Emrah; Demir, Serap; Ogan, Ayşe

2018-05-28

The modification of magnetic nanoparticles (MNPs) via different routes for biomolecule binding is an attractive area of research. Waterborne thiol-ene suspension photopolymerization (TESP) can be a useful method for preparing functional MNPs. In this study, for the very first time waterborne TESP was performed in the presence of MNPs. Neat MNPs were coated and in situ functionalized with amine groups by using thiol-ene chemistry. Engrailed-2 (EN2) protein, a potential biomarker for various cancers such as prostate cancer, bladder cancer, breast cancer and ovarian cancer, is known to be a strong binder to a specific DNA sequence (50-TAATTA-30) to regulate transcription. Anti-EN2 antibodies were immobilized onto these MNPs by physical adsorption and covalent bonding methods, respectively. The amount of the physically immobilized antibodies (0.54 mg/g) were found to be lower than the loading of the covalently bonded antibodies (1.775 mg/g). The biomarker level in the artificial solutions prepared was determined by enzyme-linked immunosorbent assay. Coated MNPs were characterized by FTIR, TGA, SEM and STEM. After TESP, the average diameter of the neat magnetite nanoparticles increased from ∼15 nm to ∼32 nm. Copyright © 2018 Elsevier B.V. All rights reserved.

Spatial redistribution of nano-particles using electrokinetic micro-focuser

NASA Astrophysics Data System (ADS)

Garcia, Daniel E.; Silva, Aleidy; Ho, Chih-Ming

2007-09-01

Current microfabrication technologies rely on top-down, photolithographic techniques that are ultimately limited by the wavelength of light. While systems for nanofabrication do exist, they frequently suffer from high costs and slow processing times, creating a need for a new manufacturing paradigm. The combination of top-down and bottom-up fabrication approaches in device construction creates a new paradigm in micro- and nano-manufacturing. The pre-requisite for the realization of the manufacturing paradigm relies on the manipulation of molecules in a deterministic and controlled manner. The use of AC electrokinetic forces, such as dielectrophoresis (DEP) and AC electroosmosis, is a promising technology for manipulating nano-sized particle in a parallel fashion. A three-electrode micro-focusing system was designed to expoit this forces in order to control the spatial distribution of nano-particles in different frequency ranges. Thus far, we have demonstrated the ability to concentrate 40 nm and 300 nm diameter particles using a 50 μm diameter focusing system. AC electroosmotic motion of the nano-particles was observed while using low frequencies (in a range of 30 Hz - 1 KHz). By using different frequencies and changing the ground location, we have manipulated the nano-particles into circular band structures with different width, and focused the nanoparticles into circular spots with different diameters. Currently, we are in the progress of optimizing the operation parameters (e.g. frequency and AC voltages) by using the technique of particle image velocimetry (PIV). In the future, design of different electrode geometries and the numerical simulation of electric field distribution will be carried out to manipulate the nano-particles into a variety of geometries.