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1

Anti-reflective optical coatings incorporating nanoparticles.  

PubMed

This paper presents a simple approach for forming anti-reflective film stacks on plastic substrates employing aqueous colloidal dispersions of metal oxide nanoparticles. Results demonstrate that it is possible to fabricate a polymeric thin film of continuously tunable refractive index over a wide range by loading the film with varying concentrations of metal oxide nanoparticles. Specifically, the refractive index for the polymer film was tuned from 1.46 to 1.54 using silica nanoparticle loadings from 50 to 0wt% and from 1.54 to 1.95 using ceria nanoparticle loadings from 0 to 90wt%, respectively. The low and high refractive index layers are then combined to create an anti-reflective coating which exhibits a reflectance spectrum, abrasion resistance, haze and transmission values that compare well with those produced using state-of-the-art vacuum based techniques. Furthermore, the results show that it is possible to begin with aqueous dispersions and then dilute them with organic solvents for use in a spin coating method to prepare the polymer-metal oxide nanoparticle composite films. PMID:21727450

Krogman, Kevin C; Druffel, Thad; Sunkara, Mahendra K

2005-07-01

2

Hybrid monolithic columns with nanoparticles incorporated for capillary electrochromatography.  

PubMed

The core-shell silica nanoparticles Fe(3)O(4)@SiO(2)/NH(2), wormlike and hexagonal SBA-15 silica were incorporated into polymethacrylate monolithic columns containing butyl methacrylate (BMA) and ethylene dimethacrylate (EDMA), respectively to develop novel stationary phases with mixing mechanism of reverse phase and ion exchange. Experimental conditions including types of nanoparticles, dispersion pattern, nanoparticles concentration, column placement mode, and reaction temperature were optimized for simple and stable column preparation. The poly(BMA-EDMA-Fe(3)O(4)@SiO(2)/NH(2)) and poly(BMA-EDMA-SBA-15/NH(2)) (both wormlike and hexagonal shape nanoparticles) monolithic columns were evaluated with mixture of organic acids as sample in capillary electrochromatography (CEC) mode and the relative column efficiency reaches 290,000plates/m. The results indicate that the incorporation of nanoparticles with various shapes enhances both selectivity and column efficiency due to high specific surface area of nanoparticles and mixing separation mechanism. In addition, poly(BMA-EDMA-Fe(3)O(4)@SiO(2)/NH(2)) monolith capillary column was applied to separation of aqueous extract of rhizoma gastrodiae and showed great potential in the method development of complex samples. PMID:22503585

Lei, Wen; Zhang, Ling-Yi; Wan, Li; Shi, Bian-Fang; Wang, Yan-Qin; Zhang, Wei-Bing

2012-05-25

3

Inorganic-organic materials incorporating alumoxane nanoparticles  

NASA Astrophysics Data System (ADS)

Chemically functionalized alumina nanoparticles (carboxylate-alumoxanes) are used as the inorganic component of a new class of inorganic-organic material. Lysine- or para-hydroxybenzoic acid-derivatized alumoxanes are prepared from the reaction of boehmite, [Al(O)(OH)]n, with the appropriate carboxylic acid. The peripheral hydroxides and amines of these alumoxanes react directly with DER 332 epoxide to form a hybrid material, or in the presence of a resin and hardener system, to form a composite material. Solid state NMR spectroscopy demonstrates that the alumoxanes are chemically bound to the resin matrix. The properties and cure times of the alumoxane materials are distinct from both the pure resins and from a physical blend of the resins with traditional fillers. A significant increase in thermal stability and tensile strength is observed for the resin systems. In order to produce molecular coupling layers, epoxides cross-linked with self-assembled monolayers (SAMs) grown on the native oxide of aluminum thin films on silicon substrates have been investigated. Specifically, SAMs have been formed by the attachment of different carboxylic acids. In order to investigate the cross-linking reaction between carboxylate monolayers and an epoxide, grown monolayers were reacted with a mono-epoxy resin. In addition to these surface materials, aluminum oxide surfaces supporting carboxylate monolayers were reacted in pairs with DER 332 to form a structural adhesive. These materials have been characterized variously by SEM, AFM, XPS, EDX, and contact angle measurements. The particle size dependence on pH of a series of alumoxanes was investigated. For each of the alumoxanes, PCS particle size measurements were obtained as a function of pH. In all cases, particle size control was afforded by variations in pH. Finally, crystal structures of several model compounds were determined by X-ray crystallography, and shown to form either sheets of dimers or tetrameric units. Through a review of structures found in the Cambridge Crystallographic Database, compounds of the type X-CH(OH)CH 2NH-Y were investigated. The results of this study lead to a generalized approach for predicting the packing motifs of racemic mixtures in polar space groups.

Vogelson, Cullen Taylor

4

Nanoparticle Incorporation of Melittin Reduces Sperm and Vaginal Epithelium Cytotoxicity  

PubMed Central

Melittin is a cytolytic peptide component of bee venom which rapidly integrates into lipid bilayers and forms pores resulting in osmotic lysis. While the therapeutic utility of free melittin is limited by its cytotoxicity, incorporation of melittin into the lipid shell of a perfluorocarbon nanoparticle has been shown to reduce its toxicity in vivo. Our group has previously demonstrated that perfluorocarbon nanoparticles containing melittin at concentrations <10 然 inhibit HIV infectivity in vitro. In the current study, we assessed the impact of blank and melittin-containing perfluorocarbon nanoparticles on sperm motility and the viability of both sperm and vaginal epithelial cells. We found that free melittin was toxic to sperm and vaginal epithelium at concentrations greater than 2 然 (p<0.001). However, melittin nanoparticles were not cytotoxic to sperm (p?=?0.42) or vaginal epithelium (p?=?0.48) at an equivalent melittin concentration of 10 然. Thus, nanoparticle formulation of melittin reduced melittin cytotoxicity fivefold and prevented melittin toxicity at concentrations previously shown to inhibit HIV infectivity. Melittin nanoparticles were toxic to vaginal epithelium at equivalent melittin concentrations ?20 然 (p<0.001) and were toxic to sperm at equivalent melittin concentrations ?40 然 (p<0.001). Sperm cytotoxicity was enhanced by targeting of the nanoparticles to the sperm surface antigen sperm adhesion molecule 1. While further testing is needed to determine the extent of cytotoxicity in a more physiologically relevant model system, these results suggest that melittin-containing nanoparticles could form the basis of a virucide that is not toxic to sperm and vaginal epithelium. This virucide would be beneficial for HIV serodiscordant couples seeking to achieve natural pregnancy. PMID:24748389

Jallouk, Andrew P.; Moley, Kelle H.; Omurtag, Kenan; Hu, Grace; Lanza, Gregory M.; Wickline, Samuel A.; Hood, Joshua L.

2014-01-01

5

Preparation of Silver Nanoparticles Incorporated Electrospun Polyurethane Nano-fibrous Mat for Wound Dressing  

Microsoft Academic Search

Polyurethane foam is currently used as an exudate absorptive wound dressing material. In this study silver (Ag) nanoparticles were incorporated into electrospun polyurethane (PU) nanofiber to enhance the antibacterial as well as wound healing properties. The electrospinning parameters were optimized for PU with and without silver nanoparticles. Silver nanoparticles were synthesized by aqueous and organic methods. The water absorption, antibacterial

Lakshmi R. Lakshman; K. T. Shalumon; Sreeja V. Nair; R. Jayakumar

2010-01-01

6

Kaempferol Induces Cell Cycle Arrest in HT-29 Human Colon Cancer Cells  

PubMed Central

Background: A greater intake of vegetables and fruits has been linked to a reduced incidence of colon cancer. Flavonoids are polyphenolic compounds which are broadly distributed in fruits and vegetables and display a remarkable spectrum of physiological activities, including anti-carcinogenic effects. The objective of this study was to determine the mechanisms by which kaempferol, a flavonol present in tea, apples, strawberries, and beans, inhibits the growth of HT-29 human colon cancer cells. Methods: To examine the effects of kaempferol on cell cycle progression in HT-29 cells, cells were treated with various concentrations (060 ?mol/L) of kaempferol. Cell proliferation and DNA synthesis were evaluated by MTT assay and [3H]thymidine incorporation assay, respectively. Fluorescence-activated cell sorting analyses were conducted to calculate cell cycle phase distribution. Western blot analyses and in vitro kinase assays were used to estimate the expression of proteins involved in the regulation of cell cycle progression and the activity of cyclin-dependent kinase (CDK)s, respectively. Results: Kaempferol decreased viable cell numbers and [3H]thymidine incorporation into DNA of HT-29 cells in a dose-dependent manner. Kaempferol induced G1 cell cycle arrest within 6 h and G2/M arrest at 12 h. Kaempferol inhibited the activity of CDK2 and CDK4 as well as the protein expression of CDK2, CDK4, cyclins D1, cyclin E, and cyclin A, and suppressed the phosphorylation of retinoblastoma protein. Additionally, kaempferol decreased the levels of Cdc25C, Cdc2, and cyclin B1 proteins, as well as the activity of Cdc2. Conclusions: The present results indicate that kaempferol induces G1 and G2/M cell cycle arrest by inhibiting the activity of CDK2, CDK4, and Cdc2. The induction of cell cycle arrest may be one of the mechanisms by which kaempferol exerts anti-carcinogenic effects in colon cancer cells. PMID:25337553

Cho, Han Jin; Park, Jung Han Yoon

2013-01-01

7

Cisplatin-incorporated nanoparticles of poly(acrylic acid-co-methyl methacrylate) copolymer  

PubMed Central

Background Although cisplatin is extensively used in the clinical field, its intrinsic toxicity limits its clinical use. We investigated nanoparticle formations of poly(acrylic acid-co-methyl methacrylate) (PAA-MMA) incorporating cisplatin and their antitumor activity in vitro and in vivo. Methods Cisplatin-incorporated nanoparticles were prepared through the ion-complex formation between acrylic acid and cisplatin. The anticancer activity of cisplatin-incorporated nanoparticles was assessed with CT26 colorectal carcinoma cells. Results Cisplatin-incorporated nanoparticles have small particle sizes of less than 200 nm with spherical shapes. Drug content was increased according to the increase of the feeding amount of cisplatin and acrylic acid content in the copolymer. The higher acrylic acid content in the copolymer induced increase of particle size and decrease of zeta potential. Cisplatin-incorporated nanoparticles showed a similar growth-inhibitory effect against CT26 tumor cells in vitro. However, cisplatin-incorporated nanoparticles showed improved antitumor activity against an animal tumor xenograft model. Conclusion We suggest that PAA-MMA nanoparticles incorporating cisplatin are promising carriers for an antitumor drug-delivery system. PMID:23966778

Lee, Kyung Dong; Jeong, Young-Il; Kim, Da Hye; Lim, Gyun-Taek; Choi, Ki-Choon

2013-01-01

8

Hybrid organic-inorganic monolithic enzymatic reactor with SBA-15 nanoparticles incorporated.  

PubMed

A novel enzymatic reactor was prepared by incorporating SBA-15 nanoparticles into hybrid organic-inorganic monolith and immobilizing trypsin with glutaraldehyde as bridging reagent. Preparation and operation conditions including nanoparticles percentage and residence time were optimized to improve the digestion efficiency. The digestion products were characterized by Matrix Assisted Laser Desorption Ionization Time of Flight Mass Spectrometry (MALDI-TOF-MS) with sequence coverage of 50%, 93% and 71% for bovine serum albumin, myoglobin and cytochrome C, while consuming only about 19s in dynamic mode. Compared with enzymatic reactor without nanoparticles incorporated, the enzymatic reactor with SBA-15 nanoparticles embedded achieved higher digestion efficiency by introducing more trypsin, which was originated from combination of SBA-15 nanoparticles and hybrid organic-inorganic monolith. PMID:24401445

Zhang, Zhaodi; Zhang, Lingyi; Zhang, Chenggong; Zhang, Weibing

2014-02-01

9

Silver nanoparticles incorporated onto ordered mesoporous silica from Tollen's reagent  

NASA Astrophysics Data System (ADS)

Noble metal nanostructures supported on mesoporous silica are bridge between traditional silica adsorbents and modern catalysts. In this work the Ag/SBA-15 mesoporous materials were synthesized and characterized. Various forms of nanosilver supported on ordered mesoporous template have been successfully obtained via proposed procedures. In all synthesized materials, Tollen's reagent (diammine silver complex [Ag(NH3)2]+) was used as a silver source. Silver nanoparticles were prepared by reduction of ammoniacal silver complex by formaldehyde in the solution of stabilizer. After reduction, Ag nanoparticles could be deposited on SBA-15, or added during traditional synthesis of SBA-15 giving silver or silver chloride nanoparticles in the combination with porous silica. Silver nanostructures as nanoparticles or nanowires were also embedded onto the SBA-15 by incipient wetness impregnation of silver ions. Absorbed silver ions were next reduced under hydrogen at high temperature. There are many advantages of utilized ammoniacal silver complex as a silver source. Proposed method is capable to synthesis of various metal nanostructures with controlled composition and morphology. The silver ammonia complex is composed of two ions surrounding and protecting the central silver ion, so it is possible to obtain very small nanoparticles using simple approach without any functionalization of external and internal surface of SBA-15. This approach allows obtaining greatly small silver nanoparticles on SBA-15 (4 nm) or nanowires depending on the metal loading amount. Moreover, the colloidal silver solution prepared from Tollen's reagent, in the presence of triblock copolymer, remains stable for a long time. Reduction of Tollen's reagent to silver colloidal solution seems to be efficient, fast and interesting approach for the preparation of supported silver nanostructures Obtained samples were characterized by powder X-ray diffraction, small angle X-ray scattering (SAXS), UV-vis spectroscopy, transmission electron microscopy (TEM), nitrogen adsorption-desorption isotherms and photoacoustic spectroscopy (PAS).

Zienkiewicz-Strza?ka, M.; Pasieczna-Patkowska, S.; Kozak, M.; Pikus, S.

2013-02-01

10

Conjugated polymer nanoparticles incorporating antifade additives for improved brightness and photostability.  

PubMed

Conjugated polymer nanoparticles with incorporated antifade agents were prepared, and ensemble and single particle measurements showed that incorporation of antifade agents effectively improves the fluorescence quantum yield and photostability of the conjugated polymer nanoparticles, likely by a combination of triplet quenching and suppression of processes involved in photogeneration of hole polarons (cations), which act as fluorescence quenchers. The photostability of conjugated polymer nanoparticles and CdSe quantum dots was compared, at both the ensemble and single particle level. The results provide confirmation of the hypothesis that quenching by photogenerated hole polarons is a key factor limiting the fluorescence quantum yield and maximum emission rate in conjugated polymer nanoparticles. Additionally, the results indicate the involvement of oxygen in photogeneration of hole polarons. The results also provide insight into the origin of quenching processes that could limit the performance of conjugated polymer devices. PMID:23214470

Tian, Zhiyuan; Yu, Jiangbo; Wang, Xiaoli; Groff, Louis C; Grimland, Jennifer L; McNeill, Jason D

2013-04-25

11

X-ray photoelectron spectroscopic study of nitrogen incorporated amorphous carbon films embedded with nanoparticles  

Microsoft Academic Search

The effect of substrate bias on X-ray photoelectron spectroscopy (XPS) study of nitrogen incorporated amorphous carbon (a-C:N) films embedded with nanoparticles deposited by filtered cathodic jet carbon arc technique is discussed. High resolution transmission electron microscope exhibited initially the amorphous structure but on closer examination the film was constituted of amorphous phase with the nanoparticle embedded in the amorphous matrix.

Ishpal; O. S. Panwar; Mahesh Kumar; Sushil Kumar

2010-01-01

12

E-beam crosslinked, biocompatible functional hydrogels incorporating polyaniline nanoparticles  

NASA Astrophysics Data System (ADS)

PANI aqueous nanocolloids in their acid-doped, inherently conductive form were synthesised by means of suitable water soluble polymers used as stabilisers. In particular, poly(vinyl alcohol) (PVA) or chitosan (CT) was used to stabilise PANI nanoparticles, thus preventing PANI precipitation during synthesis and upon storage. Subsequently, e-beam irradiation of the PANI dispersions has been performed with a 12 MeV Linac accelerator. PVA-PANI nanocolloid has been transformed into a PVA-PANI hydrogel nanocomposite by radiation induced crosslinking of PVA. CT-PANI nanoparticles dispersion, in turn, was added to PVA to obtain wall-to-wall gels, as chitosan mainly undergoes chain scission under the chosen irradiation conditions. While the obtainment of uniform PANI particle size distribution was preliminarily ascertained with laser light scattering and TEM microscopy, the typical porous structure of PVA-based freeze dried hydrogels was observed with SEM microscopy for the hydrogel nanocomposites. UV-visible absorption spectroscopy demonstrates that the characteristic, pH-dependent and reversible optical absorption properties of PANI are conferred to the otherwise optically transparent PVA hydrogels. Selected formulations have been also subjected to MTT assays to prove the absence of cytotoxicity.

Dispenza, C.; Sabatino, M.-A.; Niconov, A.; Chmielewska, D.; Spadaro, G.

2012-09-01

13

Kaempferol induces apoptosis in glioblastoma cells through oxidative stress  

Microsoft Academic Search

Despite recent advances in understanding molecular mechanisms involved in glioblastoma progression, the prognosis of the most malignant brain tumor continues to be dismal. Because the flavonoid kaempferol is known to suppress growth of a number of human malignancies, we investigated the effect of kaempferol on human glioblas- toma cells. Kaempferol induced apoptosis in glioma cells by elevating intracellular oxidative stress.

Vivek Sharma; Christy Joseph; Soumya Ghosh; Anindita Agarwal; Manoj Kumar Mishra; Ellora Sen

2007-01-01

14

Nanoparticle polymer composite volume gratings incorporating chain transfer agents for holography and slow-neutron optics.  

PubMed

We demonstrate twofold enhancement of the saturated refractive index modulation (?n(sat)) recorded in a photopolymerizable nanoparticle-acrylate polymer composite film by incorporating thiols acting as chain transfer agents. The chain transfer reaction of thiols with (meth)acrylate monomer reduces the polymer crosslinking density and facilitates the mutual diffusion of nanoparticles and monomer during holographic exposure. These modifications provide increased density modulations of nanoparticles and the formed polymer, resulting in the enhancement of ?n(sat) as high as 1.610(-2) at a wavelength of 532 nm. The incorporation of thiols also leads to shrinkage suppression and to improvement of the grating's spatial frequency response. Such simultaneous improvement is very useful for holographic applications in light and neutron optics. PMID:24978509

Fujii, Ryuta; Guo, Jinxin; Klepp, Jrgen; Pruner, Christian; Fally, Martin; Tomita, Yasuo

2014-06-15

15

Kaempferol, a mutagenic flavonol from Helichrysum simillimum.  

PubMed

Helichrysum simillimum is native to South Africa. It is used for the treatment of coughs, colds, fever, infections, headache, and menstrual pain. Extracts of this species showed mutagenic effects in the Salmonella/microsome assay. The aim of this study was to isolate and determine the mutagenic constituents of H. simillimum. Bioassay-guided fractionation of 90% aqueous methanol extracts, using Salmonella typhimurium TA98, led to the isolation of the flavonol kaempferol. PMID:19244292

Elgorashi, Ee; van Heerden, Fr; van Staden, J

2008-11-01

16

Antitumor activity of sorafenib-incorporated nanoparticles of dextran/poly(dl-lactide- co-glycolide) block copolymer  

NASA Astrophysics Data System (ADS)

Sorafenib-incoporated nanoparticles were prepared using a block copolymer that is composed of dextran and poly( DL-lactide- co-glycolide) [Dex bLG] for antitumor drug delivery. Sorafenib-incorporated nanoparticles were prepared by a nanoprecipitation-dialysis method. Sorafenib-incorporated Dex bLG nanoparticles were uniformly distributed in an aqueous solution regardless of the content of sorafenib. Transmission electron microscopy of the sorafenib-incorporated Dex bLG nanoparticles revealed a spherical shape with a diameter < 300 nm. Sorafenib-incorporated Dex bLG nanoparticles at a polymer/drug weight ratio of 40:5 showed a relatively uniform size and morphology. Higher initial drug feeding was associated with increased drug content in nanoparticles and in nanoparticle size. A drug release study revealed a decreased drug release rate with increasing drug content. In an in vitro anti-proliferation assay using human cholangiocarcinoma cells, sorafenib-incorporated Dex bLG nanoparticles showed a similar antitumor activity as sorafenib. Sorafenib-incorporated Dex bLG nanoparticles are promising candidates as vehicles for antitumor drug targeting.

Kim, Do Hyung; Kim, Min-Dae; Choi, Cheol-Woong; Chung, Chung-Wook; Ha, Seung Hee; Kim, Cy Hyun; Shim, Yong-Ho; Jeong, Young-Il; Kang, Dae Hwan

2012-01-01

17

Kaempferol Downregulates Insulin-like Growth Factor-I Receptor and ErbB3 Signaling in HT-29 Human Colon Cancer Cells  

PubMed Central

Background: Novel dietary agents for colon cancer prevention and therapy are desired. Kaempferol, a flavonol, has been reported to possess anticancer activity. However, little is known about the molecular mechanisms of the anticancer effects of kaempferol. The aim of this study was to determine the inhibitory effect of kaempferol on growth factor-induced proliferation and to elucidate its underlying mechanisms in the HT-29 human colon cancer cell line. Methods: To assess the effects of kaempferol and/or growth factors [insulin-like growth factor (IGF)-I and heregulin (HRG)-?], cells were cultured with or without 60 ?mol/L kaempferol and/or 10 nmol/L IGF-I or 20 ?g/L HRG-?. Cell proliferation, DNA synthesis, and apoptosis were determined by a cell viability assay, a [3H]thymidine incorporation assay, and Annexin-V staining, respectively. Western blotting, immunoprecipitation, and an in vitro kinase assay were conducted to evaluate expression and activation of various signaling molecules involved in the IGF-I receptor (IGF-IR) and ErbB3 signaling pathways. Results: IGF-I and HRG-? stimulated HT-29 cell growth but did not abrogate kaempferol-induced growth inhibition and apoptosis. Kaempferol reduced IGF-II secretion, HRG expression and phosphorylation of Akt and extracellular signal-regulated kinase (ERK)-1/2. Kaempferol reduced IGF-I- and HRG-?-induced phosphorylation of the IGF-IR and ErbB3, their association with p85, and phosphatidylinositol 3-kinase (PI3K) activity. Additionally, kaempferol inhibited IGF-I- and HRG-?-induced phosphorylation of Akt and ERK-1/2. Conclusions: The results demonstrate that kaempferol downregulates activation of PI3K/Akt and ERK-1/2 pathways by inhibiting IGF-IR and ErbB3 signaling in HT-29 cells. We suggest that kaempferol could be a useful chemopreventive agent against colon cancer. PMID:25337585

Lee, Hyun Sook; Cho, Han Jin; Kwon, Gyoo Taik; Park, Jung Han Yoon

2014-01-01

18

Organic solar cells incorporating buffer layers from indium doped zinc oxide nanoparticles  

Microsoft Academic Search

Monodisperse, indium doped zinc oxide (IZO) nanoparticles were prepared via the polyol-mediated synthesis and incorporated into regular and inverted poly-(3-hexylthiophene-2,5-diyl) and [6,6]-phenyl C61-butyric acid methyl ester organic photovoltaic devices as buffer layers between the active layer and the cathode. Efficient hole blocking at the particle buffer layers leads to an enhanced open-circuit voltage of the solar cells. This effect is

Andreas Puetz; Tobias Stubhan; Manuel Reinhard; Oliver Loesch; Elin Hammarberg; Silke Wolf; Claus Feldmann; Heinz Kalt; Alexander Colsmann; Uli Lemmer

2011-01-01

19

Kaempferol and quercetin glycosides from Rubus idaeus L. leaves.  

PubMed

Quercetin 3-0-beta-D-glucoside (I), quercetin and kaempferol 3-0-beta-D-galactosides (II, III), kaempferol 3-0-beta-L-arabinopyranoside (IV), kaempferol 3-0-beta-D-(6''-E-p-coumaroyl)-glucoside (tiliroside) (V) and methyl gallate (VI) were isolated from Rubus idaeus L. subspecies culture of Norna leaves and fully characterized. PMID:14714861

Gudej, Jan

2003-01-01

20

Associations between iron oxyhydroxide nanoparticle growth and metal adsorption/structural incorporation  

SciTech Connect

The interaction of metal ions and oxyanions with nanoscale mineral phases has not yet been extensively studied despite the increased recognition of their prevalence in natural systems as a significant component of geomedia. A combination of macroscopic uptake studies to investigate the adsorption behavior of As(V), Cu(II), Hg(II), and Zn(II) onto nanoparticulate goethite ({alpha}-FeOOH) as a function of aging time at elevated temperature (75 C) and synchrotron-based X-ray studies to track changes in both the sorption mode and the rate of nanoparticle growth reveal the effects that uptake has on particle growth. Metal(loid) species which sorb quickly to the iron oxyhydroxide particles (As(V), Cu(II)) appear to passivate the particle surface, impeding the growth of the nanoparticles with progressive aging; in contrast, species that sorb more slowly (Hg(II), Zn(II)) have considerably less impact on particle growth. Progressive changes in the speciation of these particular metals with time suggest shifts in the mode of metal uptake with time, possibly indicating structural incorporation of the metal(loid) into the nanoparticle; this is supported by the continued increase in uptake concomitant with particle growth, implying that metal species may transform from surface-sorbed species to more structurally incorporated forms. This type of incorporation would have implications for the long-term fate and mobility of metals in contaminated regions, and affect the strategy for potential remediation/modeling efforts.

Kim, C.S.; Lentini, C.J.; Waychunas, G.A.

2008-09-15

21

5-aminolevulinic acid-incorporated nanoparticles of methoxy poly(ethylene glycol)-chitosan copolymer for photodynamic therapy  

PubMed Central

Purpose The aim of this study was to make 5-aminolevulinic acid (5-ALA)-incorporated nanoparticles using methoxy polyethylene glycol/chitosan (PEG-Chito) copolymer for application in photodynamic therapy for colon cancer cells. Methods 5-ALA-incorporated (PEG-Chito-5-ALA) nanoparticles were prepared by ion complex formation between 5-ALA and chitosan. Protoporphyrin IX accumulation in the tumor cells and phototoxicity induced by PEG-Chito-5-ALA nanoparticles were assessed using CT26 cells in vitro. Results PEG-Chito-5-ALA nanoparticles have spherical shapes with sizes diameters 200 nm. More specifically, microscopic observation revealed a core-shell structure of PEG-Chito-5-ALA nanoparticles. 1H NMR spectra showed that 5-ALA was incorporated in the core of the nanoparticles. In the absence of light irradiation, all components such as 5-ALA, empty nanoparticles, and PEG-Chito-5-ALA nanoparticles did not affect the viability of cells. However, 5-ALA or PEG-Chito-5-ALA nanoparticles induced tumor cell death under light irradiation, and the viability of tumor cells was dose-dependently decreased according to the increase in irradiation time. In particular, PEG-Chito-5-ALA nanoparticles induced increased phototoxicity and higher protoporphyrin IX accumulation into the tumor cells than did 5-ALA alone. Furthermore, PEG-Chito-5-ALA nanoparticles accelerated apoptosis/necrosis of tumor cells, compared to 5-ALA alone. Conclusion PEG-Chito-5-ALA nanoparticles showed superior delivery capacity of 5-ALA and phototoxicity against tumor cells. These results show that PEG-Chito-5-ALA nanoparticles are promising candidates for photodynamic therapy of colon cancer cells. PMID:23589688

Chung, Chung-Wook; Chung, Kyu-Don; Jeong, Young-Il; Kang, Dae Hwan

2013-01-01

22

Formation mechanism of incorporating metal nanoparticles into highly stable metal-organic-frameworks  

NASA Astrophysics Data System (ADS)

Incorporating shape and size controlled metal nanoparticles (NPs) into metal-organic-frameworks (MOFs) shows great potential in heterogeneous catalysis. The combination of ordered nanoporous structure of MOFs and the well-defined surfaces of metal NPs provides a new tool to modulate the catalysis on the metal surface. Due to the large pore size, framework flexibility and selective interaction with gas molecules, MOFs have been widely used for gas storage with high selectivity. Among which have been developed to date, Zeolitic Imidazolate Frameworks-8 (ZIF-8) and UiO-66 show advantageous properties. The solvent resistivity and high thermal stability makes them stand out to be good candidates as shell materials in core shell catalysts. In our work, we developed an efficient way to create a yolk-shell structure of Pd nanoparticles in ZIF-8 and, at the same time, a method to incorporate the shape/size controlled Pt nanoparticles into well-defined octahedral UiO-66 nanocrystals with the control of concentration and dispersion. The formation mechanisms of both yolk-shell and core-shell structures were also studied in the work.

Tang, Yang

23

Incorporation of polyoxotungstate complexes in silica spheres and in situ formation of tungsten trioxide nanoparticles.  

PubMed

In this paper, we demonstrated a new convenient route for in situ fabrication of well separated small sized WO(3) nanoparticles in silica spheres, through a predeposition of surfactant encapsulated polyoxotungates as tungsten source, and followed by a calcination process. In a typical procedure, selected polyoxotungates with different charges were enwrapped with dioctadecyldimethylammonium cations through electrostatic interaction. Elemental analysis, thermogravimetric analysis, and spectral characterization confirmed the formation of prepared complexes with the anticipated chemical structure. The complexes were then phase-transferred into aqueous solution that predissolved surfactant cetyltrimethylammonium bromide, and finally incorporated into silica spheres through a joint sol-gel reaction with tetraethyl orthosilicate in a well dispersed state under the protection of organic layer for polyoxotungates from the alkaline reaction condition. Transmission electron microscopic images illustrated the well dispersed WO(3) nanoparticles in the size range of ca. 2.2 nm in the silica spheres after the calcination at 465 蚓. The sizes of both the silica spheres and WO(3) nanoparticles could be adjusted independently through changing the doping content to a large extent. Meanwhile, the doped polyoxotungate complexes acted as the template for the mesoporous structure in silica spheres after the calcination. Along with the increase of doping content and surfactant, the mesopore size changed little (2.0-2.9 nm), but the specific surface areas increased quite a lot. Importantly, the WO(3)-nanoparticle-doped silica spheres displayed an interesting photovoltaic property, which is favorable for the funtionalization of these nanomaterials. PMID:20715875

Zhao, Yuanyuan; Fan, Haimei; Li, Wen; Bi, Lihua; Wang, Dejun; Wu, Lixin

2010-09-21

24

Surface plasmon-enhanced electroluminescence in organic light-emitting diodes incorporating Au nanoparticles  

NASA Astrophysics Data System (ADS)

Surface plasmon-enhanced electroluminescence (EL) in an organic light-emitting diode is demonstrated by incorporating the synthesized Au nanoparticles (NPs) in the hole injection layer of poly(3,4-ethylene dioxythiophene):polystyrene sulfonic acid. An increase of 25% in the EL intensity and efficiency are achieved for devices with Au NPs, whereas the spectral and electrical properties remain almost identical to the control device. Time-resolved photoluminescence spectroscopy reveals that the EL enhancement is ascribed to the increase in spontaneous emission rate due to the plasmonic near-field effect induced by Au NPs.

Xiao, Y.; Yang, J. P.; Cheng, P. P.; Zhu, J. J.; Xu, Z. Q.; Deng, Y. H.; Lee, S. T.; Li, Y. Q.; Tang, J. X.

2012-01-01

25

Paclitaxel-incorporated nanoparticles using block copolymers composed of poly(ethylene glycol)/poly(3-hydroxyoctanoate).  

PubMed

Block copolymers composed of poly(3-hydroxyoctanoate) (PHO) and methoxy poly(ethylene glycol) (PEG) were synthesized to prepare paclitaxel-incorporated nanoparticle for antitumor drug delivery. In a (1)H-NMR study, chemical structures of PHO/PEG block copolymers were confirmed and their molecular weight (M.W.) was analyzed with gel permeation chromatography (GPC). Paclitaxel as a model anticancer drug was incorporated into the nanoparticles of PHO/PEG block copolymer. They have spherical shapes and their particle sizes were less than 100nm. In a (1)H-NMR study in D2O, specific peaks of PEG solely appeared while peaks of PHO disappeared, indicating that nanoparticles have core-shell structures. The higher M.W. of PEG decreased loading efficiency and particle size. The higher drug feeding increased drug contents and average size of nanoparticles. In the drug release study, the higher M.W. of PEG block induced the acceleration of drug release rate. The increase in drug contents induced the slow release rate of drug. In an antitumor activity study in vitro, paclitaxel nanoparticles have practically similar anti-proliferation activity against HCT116 human colon carcinoma cells. In an in vivo animal study using HCT116 colon carcinoma cell-bearing mice, paclitaxel nanoparticles have enhanced antitumor activity compared to paclitaxel itself. Therefore, paclitaxel-incorporated nanoparticles of PHO/PEG block copolymer are a promising vehicle for antitumor drug delivery. PMID:25288916

Kim, Hyun Yul; Ryu, Je Ho; Chu, Chong Woo; Son, Gyung Mo; Jeong, Young-Il; Kwak, Tae-Won; Kim, Do Hyung; Chung, Chung-Wook; Rhee, Young Ha; Kang, Dae Hwan; Kim, Hyung Wook

2014-01-01

26

Paclitaxel-incorporated nanoparticles using block copolymers composed of poly(ethylene glycol)/poly(3-hydroxyoctanoate)  

PubMed Central

Block copolymers composed of poly(3-hydroxyoctanoate) (PHO) and methoxy poly(ethylene glycol) (PEG) were synthesized to prepare paclitaxel-incorporated nanoparticle for antitumor drug delivery. In a 1H-NMR study, chemical structures of PHO/PEG block copolymers were confirmed and their molecular weight (M.W.) was analyzed with gel permeation chromatography (GPC). Paclitaxel as a model anticancer drug was incorporated into the nanoparticles of PHO/PEG block copolymer. They have spherical shapes and their particle sizes were less than 100nm. In a 1H-NMR study in D2O, specific peaks of PEG solely appeared while peaks of PHO disappeared, indicating that nanoparticles have core-shell structures. The higher M.W. of PEG decreased loading efficiency and particle size. The higher drug feeding increased drug contents and average size of nanoparticles. In the drug release study, the higher M.W. of PEG block induced the acceleration of drug release rate. The increase in drug contents induced the slow release rate of drug. In an antitumor activity study in vitro, paclitaxel nanoparticles have practically similar anti-proliferation activity against HCT116 human colon carcinoma cells. In an in vivo animal study using HCT116 colon carcinoma cell-bearing mice, paclitaxel nanoparticles have enhanced antitumor activity compared to paclitaxel itself. Therefore, paclitaxel-incorporated nanoparticles of PHO/PEG block copolymer are a promising vehicle for antitumor drug delivery. PMID:25288916

2014-01-01

27

Recent Updates of DNA Incorporated in Carbon Nanotubes and Nanoparticles for Electrochemical Sensors and Biosensors  

PubMed Central

Innovations in the field of electrochemical sensors and biosensors are of much importance nowadays. These devices are designed with probes and micro electrodes. The miniaturized designs of these sensors allow analyses of materials without damaging the samples. Some of these sensors are also useful for real time analysis within the host system, so these sensors are considered to be more advantageous than other types of sensors. The active sensing materials used in these types of sensors can be any material that acts as a catalyst for the oxidation or reduction of particular analyte or set of analytes. Among various kinds of sensing materials, deoxyribonucleic acid (DNA), carbon nanotubes (CNTs) and nanoparticles have received considerable attraction in recent years. DNA is one of the classes of natural polymers, which can interact with CNTs and nanoparticles to form new types of composite materials. These composite materials have also been used as sensing materials for sensor applications. They have advantages in characteristics such as extraordinary low weight and multifunctional properties. In this article, advantages of DNA incorporated in CNT and nanoparticle hybrids for electrochemical sensors and biosensors are presented in detail, along with some key results noted from the literature.

Yogeswaran, Umasankar; Thiagarajan, Soundappan; Chen, Shen-Ming

2008-01-01

28

Preparation and Characterization of Selenium Incorporated Guar Gum Nanoparticle and Its Interaction with H9c2 Cells  

PubMed Central

This study deals with the preparation and characterization of selenium incorporated guar gum nanoparticle (SGG), and its effect on H9c2 cardiomyoblast. Herein, nanoprecipitation techniques had been employed for the preparation of SGG nanoparticle. The prepared nanoparticle had been subjected to various types of analytical techniques like transmission electron microscopy (TEM), X-ray diffraction (XRD) and particle size analysis to confirm the characteristics of nanoparticle as well as for selenium incorporation. Physical characterization of nanoparticle showed that the size of nanoparticles increase upto ?69173 nm upon selenium incorporation from ?41132 nm. Then the prepared nanoparticles were evaluated for its effect on H9c2 cells. In this regard, the effect of nanoparticle on various vital parameters of H9c2 cells was studied. Parameters like cell viability, uptake of selenium incorporated guar gum nanoparticle by the cells, effect of SGG on DNA integrity, apoptosis, reactive oxygen species generation, alteration in transmembrane potential of mitochondria and cytoskeletal integrity had been investigated. Viability results showed that up to 25 nM of SGG was safe (10.31%) but beyond that it induces cytotoxicity. Cellular uptake of selenium showed that cell permeability for SGG is significantly high compared to normal selenium (7.2 nM of selenium for 25 nM SGG compared with 5.2 nM selenium for 25 nM sodium selenite). There was no apoptosis with SGG and also it protects DNA from hydroxyl radical induced breakage. Likewise no adverse effect on mitochondria and cytoskeleton was observed for 25 nM of SGG. Overall results reveal that SGG is highly suitable for biomedical research application. PMID:24098647

Soumya, Rema Sreenivasan; Vineetha, Vadavanath Prabhakaran; Reshma, Premachandran Latha; Raghu, Kozhiparambil Gopalan

2013-01-01

29

Hair dye-incorporated poly-?-glutamic acid/glycol chitosan nanoparticles based on ion-complex formation  

PubMed Central

Background p-Phenylenediamine (PDA) or its related chemicals are used more extensively than oxidative hair dyes. However, permanent hair dyes such as PDA are known to have potent contact allergy reactions in humans, and severe allergic reactions are problematic. Methods PDA-incorporated nanoparticles were prepared based on ion-complex formation between the cationic groups of PDA and the anionic groups of poly(?-glutamic acid) (PGA). To reinforce PDA/PGA ion complexes, glycol chitosan (GC) was added. PDA-incorporated nanoparticles were characterized using field-emission scanning electron microscopy, Fourier- transform infrared (FT-IR) spectroscopy, dynamic light scattering, and powder X-ray diffractometry (XRD). Results Nanoparticles were formed by ion-complex formation between the amine groups of PDA and the carboxyl groups of PGA. PDA-incorporated nanoparticles are small in size (<100 nm), and morphological observations showed spherical shapes. FT-IR spectra results showed that the carboxylic acid peak of PGA decreased with increasing PDA content, indicating that the ion complexes were formed between the carboxyl groups of PGA and the amine groups of PDA. Furthermore, the intrinsic peak of the carboxyl groups of PGA was also decreased by the addition of GC. Intrinsic crystalline peaks of PDA were observed by XRD. This crystalline peak of PDA was completely nonexistent when nanoparticles were formed by ion complex between PDA, PGA, and GC, indicating that PDA was complexed with PGA and no free drug existed in the formulation. During the drug-release experiment, an initial burst release of PDA was observed, and then PDA was continuously released over 1 week. Cytotoxicity testing against HaCaT human skin keratinocyte cells showed PDA-incorporated nanoparticles had lower toxicity than PDA itself. Furthermore, PDA-incorporated nanoparticles showed reduced apoptosis and necrosis reaction at HaCaT cells. Conclusion The authors suggest that these microparticles are ideal candidates for a vehicle for decreasing side effects of hair dye. PMID:22131834

Lee, Hye-Young; Jeong, Young-IL; Choi, Ki-Choon

2011-01-01

30

All-trans retinoic acid-incorporated nanoparticles of deoxycholic acid-conjugated dextran for treatment of CT26 colorectal carcinoma cells  

PubMed Central

Purpose All-trans retinoic acid (RA)-incorporated nanoparticles were prepared using deoxycholic acid-conjugated dextran (DexDA). Anticancer activity of RA-incorporated DexDA nanoparticles were tested in vitro and in vivo. Methods RA-incorporated nanoparticles were prepared by dialysis. Antiproliferative and anti-invasive potential of RA-incorporated nanoparticles were studied using CT26 colorectal carcinoma cells. Results RA-incorporated nanoparticles have small particle sizes of around 70300 nm and spherical shapes. The higher drug-feeding ratio and higher substitution degree of deoxycholic acid in the conjugates resulted in higher drug contents, lower loading efficiency, and larger particle size. RA release rate became slower at higher drug contents and higher substitution degree of deoxycholic acid in the DexDA conjugates. The antiproliferation activity, anti-invasive activity, and matrix metalloproteinase 2 expression of RA-incorporated nanoparticles against CT26 cells in vitro was similar to RA. However, RA-incorporated nanoparticles had superior antimetastatic activity in an animal pulmonary metastatic model of CT26 cells compared to RA itself. Conclusion RA-incorporated nanoparticles showed similar anticancer activity in vitro and superior antimetastatic activity in vivo in a pulmonary metastatic model of CT26 cells. We suggest that RA-incorporated nanoparticles are promising vehicles for efficient delivery of RA. PMID:23390366

Jeong, Young Il; Chung, Kyu Don; Kim, Da Hye; Kim, Yoon Hyuk; Lee, Yeon Soo; Choi, Ki Choon

2013-01-01

31

Nanocomposites Fabricated by a Combination of Green Compact Nanoparticle Incorporation and Ultrasonic Treatment of the Melted Compact  

NASA Astrophysics Data System (ADS)

Thixoforming is a type of semi-solid processing which is based on forming metals in the semi-solid state rather than fully liquid or solid state. There have been no reports of the thixoforming of nanocomposites in the literature. The incorporation of ceramic nanoparticles into liquid metals is a challenging task for the fabrication of metal matrix nanocomposites due to their large surface-to-volume ratio and poor wettability. Previous research work by a number of workers has highlighted the challenges with the incorporation of nanoparticles into liquid aluminum alloy. In the present study, SiC and TiB2 nanoparticles with an average diameter between 20 and 30 nm were firstly incorporated into green compacts by a powder forming route, and then the compacts were melted and treated ultrasonically. The microstructural studies reveal that the engulfment and relatively effective distribution of the nanoparticles into the melt were achieved. The hardness was considerably improved with only 0.8 wt pct addition of the nanoparticles. The nanocomposites were successfully thixoformed at a solid fraction between 0.65 and 0.70. The microstructures, hardness, and tensile mechanical properties of the thixoformed nanocomposites were investigated and compared with those of the as-received A356 and thixoformed A356 alloys. The tensile properties of the thixoformed nanocomposites were significantly enhanced compared to thixoformed A356 alloy without reinforcement, indicating the strengthening effects of the nanoparticles.

Kandemir, Sinan; Atkinson, Helen V.; Weston, David P.; Hainsworth, Sarah V.

2014-11-01

32

Study of the interaction of kaempferol with bovine serum albumin  

Microsoft Academic Search

The binding of kaempferol with bovine serum albumin (BSA) was investigated at three temperatures, 296, 310 and 318 K, by the fluorescence, circular dichroism (CD) and Fourier transform infrared spectroscopy (FT-IR) at pH 7.40. The CD and FT-IR studies indicate that kaempferol binds strongly to BSA. The association constant K was determined by SternVolmer equation based on the quenching of

Jianniao Tian; Jiaqin Liu; Xuan Tian; Zhide Hu; Xingguo Chen

2004-01-01

33

Enhanced visualization of biodegradable polymeric vascular scaffolds by incorporation of gold, silver and magnetite nanoparticles.  

PubMed

Due to improved tissue regeneration and the enabling of post-operative minimally invasive interventions in the same vessel segment, biodegradable polymeric scaffolds represent a competitive approach to permanent metallic stents in vascular applications. Despite these advantages some challenges, such as the improvement of the scaffold mechanics and enhancement of scaffold visibility during the implantation procedure, are persisting. Therefore, the scope of our studies was to investigate the potential of gold, silver and magnetite nanoparticles incorporated in a polymeric blend of poly(L-lactide)/poly(4-hydroxybutyrate) for image enhancement in X-ray, magnetic resonance or near-infrared imaging. Their impact on mechanical properties of such modified scaffold materials was also evaluated. PMID:22492201

Luderer, Frank; Begerow, Ivonne; Schmidt, Wolfram; Martin, Heiner; Grabow, Niels; Bnger, Carsten M; Schareck, Wolfgang; Schmitz, Klaus-Peter; Sternberg, Katrin

2013-08-01

34

Enhanced recovery and dissolution of griseofulvin nanoparticles from surfactant-free nanocomposite microparticles incorporating wet-milled swellable dispersants.  

PubMed

Abstract Nanocomposite microparticles (NCMPs) incorporating drug nanoparticles and wet-milled swellable dispersant particles were investigated as a surfactant-free drug delivery vehicle with the goal of enhancing the nanoparticle recovery and dissolution rate of poorly water-soluble drugs. Superdisintegrants were used as inexpensive, model, swellable dispersant particles by incorporating them into NCMP structure with or without wet-stirred media milling along with the drug. Suspensions of griseofulvin (GF, model drug) along with various dispersants produced by wet-milling were coated onto Pharmatose to prepare NCMPs in a fluidized bed process. Hydroxypropyl cellulose (HPC, polymer) alone and with sodium dodecyl sulfate (SDS, surfactant) was used as base-line stabilizer/dispersant during milling. Croscarmellose sodium (CCS, superdisintegrant) and Mannitol were used as additional dispersants to prepare surfactant-free NCMPs. Nanoparticle recovery during redispersion and dissolution of the various GF-laden NCMPs were examined. Suspensions prepared by co-milling GF/HPC/CCS or milling GF/HPC/SDS were stable after 30 h of storage. After drying, due to its extensive swelling capacity, incorporation of wet-milled CCS in the NCMPs caused effective breakage of the NCMP structure and bursting of nanoparticle clusters, ultimately leading to fast recovery of the GF nanoparticles. Optimized wet co-milling and incorporation of CCS in NCMP structure led to superior dispersant performance over incorporation of unmilled CCS or physically mixed unmilled CCS with NCMPs. The enhanced redispersion correlated well with the fast GF dissolution from the NCMPs containing either CCS particles or SDS. Overall, swellable dispersant (CCS) particles, preferably in multimodal size distribution, enable a surfactant-free formulation for fast recovery/dissolution of the GF nanoparticles. PMID:23981202

Bhakay, Anagha; Azad, Mohammad; Vizzotti, Emanuel; Dave, Rajesh N; Bilgili, Ecevit

2014-11-01

35

Beneficial properties of selenium incorporated guar gum nanoparticles against ischemia/reperfusion in cardiomyoblasts (H9c2).  

PubMed

Nanotechnology for the treatment and diagnosis has been emerging recently as a potential area of research and development. In the present study, selenium incorporated guar gum nanoparticles have been prepared by nanoprecipitation and characterized by transmission electron microscopy and particle size analysis. The nanoparticles were screened for antioxidant potential (metal chelation, total reducing power and hydroxyl radical scavenging activity) and were evaluated against the cell line based cardiac ischemia/reperfusion model with special emphasis on oxidative stress and mitochondrial parameters. The cell based cardiac ischemia model was employed using H9c2 cell lines. Investigations revealed that there was a significant alteration (P ? 0.05) in the innate antioxidant status (glutathione?, glutathione peroxidase?, thioredoxin reductase?, superoxide dismutase?, catalase?, lipid peroxidation?, protein carbonyl?, xanthine oxidase? and caspase 3 activity?), mitochondrial functions (reactive oxygen species generation, membrane potential, and pore opening) and calcium homeostasis (calcium ATPase and intracellular calcium overload) during both ischemia and reperfusion. For comparative evaluation, selenium, guar gum and selenium incorporated guar gum nanoparticles were evaluated for their protective properties against ischemia/reperfusion. The study reveals that selenium incorporated guar gum nanoparticles were better at protecting the cells from ischemia/reperfusion compared to selenium and guar gum nanoparticles. The potent antioxidant capability shown by the sample in in vitro assays may be the biochemical basis of its better biological activity. Further, the nanodimensions of the particle may be the additional factor responsible for its better effect. PMID:25307064

Soumya, R S; Vineetha, V P; Salin Raj, P; Raghu, K G

2014-10-22

36

Kaempferol, a potential cytostatic and cure for inflammatory disorders.  

PubMed

Kaempferol (3,5,7-trihydroxy-2-(4-hydroxyphenyl)-4H-1-benzopyran-4-one) is a flavonoid found in many edible plants (e.g., tea, broccoli, cabbage, kale, beans, endive, leek, tomato, strawberries, and grapes) and in plants or botanical products commonly used in traditional medicine (e.g., Ginkgo biloba, Tilia spp, Equisetum spp, Moringa oleifera, Sophora japonica and propolis). Its anti-oxidant/anti-inflammatory effects have been demonstrated in various disease models, including those for encephalomyelitis, diabetes, asthma, and carcinogenesis. Moreover, kaempferol act as a scavenger of free radicals and superoxide radicals as well as preserve the activity of various anti-oxidant enzymes such as catalase, glutathione peroxidase, and glutathione-S-transferase. The anticancer effect of this flavonoid is mediated through different modes of action, including anti-proliferation, apoptosis induction, cell-cycle arrest, generation of reactive oxygen species (ROS), and anti-metastasis/anti-angiogenesis activities. In addition, kaempferol was found to exhibit its anticancer activity through the modulation of multiple molecular targets including p53 and STAT3, through the activation of caspases, and through the generation of ROS. The anti-tumor effects of kaempferol have also been investigated in tumor-bearing mice. The combination of kaempferol and conventional chemotherapeutic drugs produces a greater therapeutic effect than the latter, as well as reduces the toxicity of the latter. In this review, we summarize the anti-oxidant/anti-inflammatory and anticancer effects of kaempferol with a focus on its molecular targets and the possible use of this flavonoid for the treatment of inflammatory diseases and cancer. PMID:25147152

Rajendran, Peramaiyan; Rengarajan, Thamaraiselvan; Nandakumar, Natarajan; Palaniswami, Rajendran; Nishigaki, Yutaka; Nishigaki, Ikuo

2014-10-30

37

Hemoglobin-Albumin Cluster Incorporating a Pt Nanoparticle: Artificial O2 Carrier with Antioxidant Activities  

PubMed Central

A covalent coreshell structured protein cluster composed of hemoglobin (Hb) at the center and human serum albumins (HSA) at the periphery, Hb-HSAm, is an artificial O2 carrier that can function as a red blood cell substitute. Here we described the preparation of a novel Hb-HSA3 cluster with antioxidant activities and its O2 complex stable in aqueous H2O2 solution. We used an approach of incorporating a Pt nanoparticle (PtNP) into the exterior HSA unit of the cluster. A citrate reduced PtNP (1.8 nm diameter) was bound tightly within the cleft of free HSA with a binding constant (K) of 1.1107 M?1, generating a stable HSA-PtNP complex. This platinated protein showed high catalytic activities for dismutations of superoxide radical anions (O2) and hydrogen peroxide (H2O2), i.e., superoxide dismutase and catalase activities. Also, Hb-HSA3 captured PtNP into the external albumin unit (K?=?1.1107 M?1), yielding an Hb-HSA3(PtNP) cluster. The association of PtNP caused no alteration of the protein surface net charge and O2 binding affinity. The peripheral HSA-PtNP shell prevents oxidation of the core Hb, which enables the formation of an extremely stable O2 complex, even in H2O2 solution. PMID:25310133

Hosaka, Hitomi; Haruki, Risa; Yamada, Kana; Bottcher, Christoph; Komatsu, Teruyuki

2014-01-01

38

Linear and nonlinear optical properties of KDP crystals with incorporated Al2O3?nH2O nanoparticles  

NASA Astrophysics Data System (ADS)

Optical and nonlinear optical properties of a novel composite system based on KDP single crystals with embedded nanoparticles of nanostructured oxyhydroxide of aluminum (Al2O3搖H2O, NOA), were studied. KDP crystals with NOA nanoparticles (KDP:NOA) possess high optical quality and homogeneity. Optical spectroscopy showed the presence of an absorption band at 270 nm caused by NOA nanoparticles incorporated in the KDP matrix. There was observed an enhancement of nonlinear refractive index and inversion of its sign in KDP:NOA crystals in comparison with nominally pure KDP crystals under excitation of picosecond laser pulses. The obtained results demonstrate that KDP:NOA is a promising composite material for optoelectronics and nonlinear optics.

Pritula, I. M.; Kosinova, A. V.; Bezkrovnaya, O. N.; Kolybaeva, M. I.; Puzikov, V. M.; Lopin, A. V.; Tkachenko, V. F.; Kopylovsky, M. A.; Yatsyna, V. O.; Gayvoronsky, V. Ya.

2013-10-01

39

On the incorporation of Rhodamine B and 2?,7?-dichlorofluorescein dyes in silica: Synthesis of fluorescent nanoparticles  

NASA Astrophysics Data System (ADS)

The present paper reports the incorporation of 2?,7?-dichlorofluorescein (DCF) and Rhodamine B (RhB) dyes in silica nanoparticles by using the St鐽er's method with some modifications. Based on infrared and electronic spectroscopies, these dyes were successfully incorporated resulting in fluorescent nanomaterials of an average size of 80 nm. A composite fluorescent nanomaterial containing both dyes was also synthesized and showed the occurrence of F顤ster resonant energy transfer process (FRET) with the average distance between the donor (DCF) and acceptor (RhB) of 3.6 nm. Furthermore, these fluorescent nanoparticles were modified with folic acid producing nanomaterials whose Zeta potential values were in the range of -2 to -13 mV. These values are consistent with the low dispersivity observed by TEM micrographs. Altogether, these suitable properties can lead to the development of nanomaterials for cancer bioimaging and drug release.

Gomes, Elis C. C.; de Carvalho, Idalina M. M.; Di鏬enes, Izaura C. N.; de Sousa, Eduardo H. S.; Longhinotti, Elisane

2014-05-01

40

Cytotoxicity of Paclitaxel Incorporated in PLGA Nanoparticles on Hypoxic Human Tumor Cells  

Microsoft Academic Search

PurposeThe aim of this work was to prepare paclitaxel-loaded PLGA nanoparticles and determine cytotoxicity of released paclitaxel\\u000a for two hypoxic human tumor cell lines: breast carcinoma (MCF-7) and carcinoma cervicis (HeLa).\\u000a \\u000a \\u000a \\u000a MethodsPoly(D,L-lactide-co-glycolide) (PLGA) nanoparticles containing paclitaxel were prepared by o\\/w emulsification-solvent evaporation\\u000a method. Physicochemical characteristics of nanoparticles were studied. Cellular uptake of nanoparticles was evaluated by transmission\\u000a electronic microscopy and

Cheng Jin; Ling Bai; Hong Wu; Wenjie Song; Guozhen Guo; Kefeng Dou

2009-01-01

41

ANTIDEPRESSANT EFFECT OF KAEMPFEROL, A CONSTITUENT OF SAFFRON (CROCUS SATIVUS) PETAL, IN MICE AND RATS  

Microsoft Academic Search

The antidepressant activity of kaempferol, a Crocus sativus petal constituent, was evaluated using forced swimming test in mice and rat. Fluoxetine (20 mg\\/kg), as a positive control, and kaempferol (100 and 200 mg\\/kg in mice and 50 mg\\/kg in rats) intraperitoneally reduced immobility in mice. This study confirmed the antidepressant effect of kaempferol in mice and rats.

Hossein Hosseinzadeh; Vahidehsadat Motamedshariaty; Farzin Hadizadeh

42

Effects of starch on nitrous acid-induced oxidation of kaempferol and inhibition of ?-amylase-catalysed digestion of starch by kaempferol under conditions simulating the stomach and the intestine.  

PubMed

Kaempferol glycosides can be hydrolyzed to their aglycone kaempferol during cooking under acidic conditions and in the oral cavity and the intestine by glycosidases. Kaempferol was oxidised by nitrite under acidic conditions (pH 2.0) to produce nitric oxide (NO), and the nitrite-induced oxidation of kaempferol was enhanced and inhibited by 10 and 100mg of starch ml(-1), respectively. The opposite effects of starch were discussed by considering the binding of kaempferol to starch and starch-dependent inhibition of the accessibility of nitrous acid to kaempferol. Kaempferol inhibited ?-amylase-catalysed starch digestion by forming starch/kaempferol complexes, and the inhibitory effects increased in the order of amylopectinkaempferol were discussed to be due to the difference in binding sites of kaempferol between amylose and amylopectin. From the present study, dual-function of kaempferol became apparent in the digestive tract. PMID:23768363

Takahama, Umeo; Hirota, Sachiko

2013-11-01

43

Incorporation of essential oils and nanoparticles in pullulan films to control foodborne pathogens on meat and poultry products.  

PubMed

The incorporation of essential oils and nanotechnology into edible films has the potential to improve the microbiological safety of foods. The aim of this study was to evaluate the effectiveness of pullulan films containing essential oils and nanoparticles against 4 foodborne pathogens. Initial experiments using plate overlay assays demonstrated that 2% oregano essential oil was active against Staphylococcus aureus and Salmonella Typhimurium, whereas Listeria monocytogenes and Escherichia coli O157:H7 were not inhibited. Two percent rosemary essential oil was active against S. aureus, L. monocytogenes, E. coli O157:H7, and S. Typhimurium, when compared with 1%. Zinc oxide nanoparticles at 110 nm were active against S. aureus, L. monocytogenes, E. coli O157:H7, and S. Typhimurium, when compared with 100 or 130 nm. Conversely, 100 nm silver (Ag) nanoparticles were more active against S. aureus than L. monocytogenes. Using the results from these experiments, the compounds exhibiting the greatest activity were incorporated into pullulan films and found to inhibit all or some of the 4 pathogens in plate overlay assays. In challenge studies, pullulan films containing the compounds effectively inhibited the pathogens associated with vacuum packaged meat and poultry products stored at 4 蚓 for up to 3 wk, as compared to control films. Additionally, the structure and cross-section of the films were evaluated using electron microscopy. The results from this study demonstrate that edible films made from pullulan and incorporated with essential oils or nanoparticles may improve the safety of refrigerated, fresh or further processed meat and poultry products. PMID:24621108

Morsy, Mohamed K; Khalaf, Hassan H; Sharoba, Ashraf M; El-Tanahi, Hassan H; Cutter, Catherine N

2014-04-01

44

Cyclodextrins-Kaempferol Inclusion Complexes: Spectroscopic and Reactivity Studies  

Microsoft Academic Search

The slightly water-soluble flavonoid kaempferol (KAE) and its inclusion complexes with ?-cyclodextrin (?CD), hydroxypropyl-?-cyclodextrin (HP?CD) or heptakis-2,6-O-dimethyl-?-cyclodextrin (DM?CD) were investigated. The stoichiometric ratios and association constants describing the extent of the formation of the complexes\\u000a have been determined. Binding constants, estimated from fluorescence studies at different temperatures, were analyzed so as\\u000a to gain information about the mechanisms involved in the

Carolina Jullian; Victor Brossard; Iv嫕 Gonzalez; Muriel Alfaro; Claudio Olea-Azar

2011-01-01

45

Mechanism of enhanced oral absorption of hydrophilic drug incorporated in hydrophobic nanoparticles  

PubMed Central

Hydroxysafflor yellow A (HSYA) is an effective ingredient of the Chinese herb Carthamus tinctorius L, which has high water solubility and low oral bioavailability. This research aims to develop a hydrophobic nanoparticle that can enhance the oral absorption of HSYA. Transmission electron microscopy and freeze-fracture replication transmission election microscopy showed that the HSYA nanoparticles have an irregular shape and a narrow size distribution. Zonula occludens 1 protein (ZO1) labeling showed that the nanoparticles with different dilutions produced an opening in the tight junctions of Caco-2 cells without inducing cytotoxicity to the cells. Both enhanced uptake in Caco-2 cells monolayer and increased bioavailability in rats for HSYA nanoparticles indicated that the formulation could improve bioavailability of HSYA significantly after oral administration both in vitro and in vivo. PMID:23935363

Lv, Liang-Zhong; Tong, Chen-Qi; Yu, Jia; Han, Min; Gao, Jian-Qing

2013-01-01

46

Large sensitivity enhancement in semiconducting organic field effect transistor sensors through incorporation of ultra-fine platinum nanoparticles  

SciTech Connect

We report remarkable improvement in sensitivity of pentacene-based field effect transistor devices towards trace nitro-aromatic explosive vapors through the incorporation of high density, sub-2?nm platinum nanoparticles (NPs) within these structures. Exploiting the unique electronic properties of these NPs, we have demonstrated a detection limit of 56.6 parts per billion of 2,4-dinitrotoluene (DNT) vapor while control samples without any embedded NPs showed no observable sensitivity to DNT vapor. We attribute this remarkable enhancement in sensitivity to the ability of these NPs to function as discrete nodes, participating in the charge transfer with adsorbed nitro-aromatic molecules.

Zheng, Haisheng; Ramalingam, Balavinayagam; Korampally, Venumadhav; Gangopadhyay, Shubhra, E-mail: gangopadhyays@missouri.edu [Department of Electrical and Computer Engineering, University of Missouri, Columbia, Missouri 65201 (United States)] [Department of Electrical and Computer Engineering, University of Missouri, Columbia, Missouri 65201 (United States)

2013-11-04

47

Interfacial Activity Assisted Surface Functionalization: A Novel Approach to Incorporate Maleimide Functional Groups and cRGD Peptide on Polymeric Nanoparticles for Targeted Drug Delivery  

PubMed Central

Nanoparticles formulated using poly(D,L-lactide-co-glycolide) (PLGA) copolymer have emerged as promising carriers for targeted delivery of a wide variety of payloads. However, an important drawback with PLGA nanoparticles is the limited types of functional groups available on the surface for conjugation to targeting ligands. In the current report, we demonstrate that the Interfacial Activity Assisted Surface Functionalization (IAASF) technique can be used to incorporate reactive functional groups such as maleimide onto the surface of PLGA nanoparticles. The surface maleimide groups were used to conjugate cRGD peptide to nanoparticles. The cRGD peptide targets ?v?3 integrins overexpressed on tumor vasculature and some tumor cells, and was used as model targeting ligand in this study. Incorporation of biologically active cRGD peptide on the surface of nanoparticles was confirmed by in vitro cell uptake studies and in vivo tumor accumulation studies. Functionalization of nanoparticles with cRGD peptide increased the cellular uptake of nanoparticles 23-fold, and this enhancement in uptake was substantially reduced by the presence of excess cRGD molecules. In a syngeneic mouse 4T1 tumor model, cRGD functionalization resulted in increased accumulation and retention of nanoparticles in the tumor tissue (nearly 2-fold greater area under the curve), confirming the in vivo activity of cRGD functionalized nanoparticles. In conclusion, the IAASF technique enabled the incorporation of reactive maleimide groups on PLGA nanoparticles, which in turn permitted efficient conjugation of biologically active cRGD peptide to the surface of PLGA nanoparticles. PMID:20527782

Toti, Udaya S.; Guru, Bharath Raja; Grill, Alex E.; Panyam, Jayanth

2010-01-01

48

Incorporation of copper nanoparticles into paper for point-of-use water purification.  

PubMed

As a cost-effective alternative to silver nanoparticles, we have investigated the use of copper nanoparticles in paper filters for point-of-use water purification. This work reports an environmentally benign method for the direct in situ preparation of copper nanoparticles (CuNPs) in paper by reducing sorbed copper ions with ascorbic acid. Copper nanoparticles were quickly formed in less than 10min and were well distributed on the paper fiber surfaces. Paper sheets were characterized by x-ray diffraction, scanning electron microscopy, energy dispersive x-ray spectroscopy, and atomic absorption spectroscopy. Antibacterial activity of the CuNP sheets was assessed for by passing Escherichia coli bacteria suspensions through the papers. The effluent was analyzed for viable bacteria and copper release. The CuNP papers with higher copper content showed a high bacteria reduction of log 8.8 for E. coli. The paper sheets containing copper nanoparticles were effective in inactivating the test bacteria as they passed through the paper. The copper levels released in the effluent water were below the recommended limit for copper in drinking water (1ppm). PMID:25014431

Dankovich, Theresa A; Smith, James A

2014-10-15

49

Tunable solid-state lasers incorporating dye-doped, polymer-nanoparticle gain media  

NASA Astrophysics Data System (ADS)

Tunable laser action in the visible spectrum has been established for what is believed to be the first time by use of dye-doped, polymer-silica nanoparticle gain media. The silica nanoparticles, ranging from 9 to 12 nm in diameter, appear to be uniformly dispersed in the poly(methyl methacrylate) matrix because the optical homogeneity of the gain medium is maintained. With Rhodamine 6G dye and 30% weight-by-weight silica nanoparticles, laser action was established in the 567-603-nm range. At the peak wavelength (? ~ 580 nm), laser conversion efficiency is ~63% at a beam divergence of 1.9 mrad (~1.3 times the diffraction limit). The new solid-state gain medium also exhibits a reduction in |?n/?T|.

Duarte, F. J.; James, R. O.

2003-11-01

50

White organic light-emitting devices incorporating nanoparticles of II VI semiconductors  

NASA Astrophysics Data System (ADS)

A blue-green fluorescent organic dye and red-emitting nanoparticles, based on II-VI semiconductors, have been used together in the fabrication of white organic light-emitting devices. In this work, the materials were combined in two different ways: in the form of a blend, and as separate layers deposited on the opposite sides of the substrate. The blended-layer structure provided purer white emission. However, this device also exhibited a number of disadvantages, namely a high drive voltage, a low efficiency and some colour instability. These problems could be avoided by using a device structure that was fabricated using separate dye and nanoparticle layers.

Ahn, Jin H.; Bertoni, Cristina; Dunn, Steve; Wang, Changsheng; Talapin, Dmitri V.; Gaponik, Nikolai; Eychmller, Alexander; Hua, Yulin; Bryce, Martin R.; Petty, Michael C.

2007-08-01

51

Photoacoustic molecular imaging of angiogenesis using theranostic ???3-targeted copper nanoparticles incorporating a sn-2 lipase-labile fumagillin prodrug  

NASA Astrophysics Data System (ADS)

Photoacoustic (PA) tomography imaging is an emerging, versatile, and noninvasive imaging modality, which combines the advantages of both optical imaging and ultrasound imaging. It opens up opportunities for noninvasive imaging of angiogenesis, a feature of skin pathologies including cancers and psoriasis. In this study, high-density copper oleate encapsulated within a phospholipid surfactant (CuNPs) generated a soft nanoparticle with PA contrast comparable to gold. Within the near-infrared window, the copper nanoparticles can provide a signal more than 7 times higher that of blood. ???3-targeted of CuNPs in a Matrigel mouse model demonstrated prominent PA contrast enhancement of the neovasculature compared to mice given nontargeted or competitively inhibited CuNPs. Incorporation of a sn-2 lipase-labile fumagillin prodrug into the CuNPs produced marked antiangiogenesis in the same model, demonstrating the theranostic potential of a PA agent for the first time in vivo. With a PA signal comparable to gold-based nanoparticles yet a lower cost and demonstrated drug delivery potential, ???3-targeted CuNPs hold great promise for the management of skin pathologies with neovascular features.

Zhang, Ruiying; Cai, Xin; Yang, Xiaoxia; Senpan, Angana; Allen, John S.; Pan, Dipanjan; Lanza, Gregory M.; Wang, Lihong V.

2014-03-01

52

Separation of kaempferols in Impatients balsamina flowers by capillary electrophoresis with electrochemical detection.  

PubMed

Capillary electrophoresis with wall-jet amperometric detection was used to detect kaempferol and its derivatives kaempferol-3-glucoside, kaempferol-3-glucosylrhamnoside and kaempferol-3-(p-coumaroyl)glucoside. The influence of buffer pH on separation was investigated and optimized. With a phosphate buffer at pH 7.5, nearly complete separation of the four kaempferols was achieved according to their different electrophoretic mobilities. The detection potential was also evaluated and optimized. At detection potential of +0.80 V vs. saturated calomel electrode, an amperometric response with high sensitivity and stability was obtained for these four compounds. Detection limit estimated for all the kaempferols examined was less than 1.4 fmol, based on S/N=3. The use of this method for the separation and detection of these compounds present in balsam flowers (Impatiens balsamina) is reported. PMID:11269529

Hua, L; Peng, Z; Chia, L S; Goh, N K; Tan, S N

2001-02-16

53

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

PubMed

We report the first example of arsenite and arsenate removal from water by incorporation of arsenic into the structure of nanocrystalline iron(III) oxide. Specifically, we show the capability to trap arsenic into the crystal structure of ?-Fe2O3 nanoparticles that are in situ formed during treatment of arsenic-bearing water with ferrate(VI). In water, decomposition of potassium ferrate(VI) yields nanoparticles having core-shell nanoarchitecture with a ?-Fe2O3 core and a ?-FeOOH shell. High-resolution X-ray photoelectron spectroscopy and in-field (57)Fe M飉sbauer spectroscopy give unambiguous evidence that a significant portion of arsenic is embedded in the tetrahedral sites of the ?-Fe2O3 spinel structure. Microscopic observations also demonstrate the principal effect of As doping on crystal growth as reflected by considerably reduced average particle size and narrower size distribution of the "in-situ" sample with the embedded arsenic compared to the "ex-situ" sample with arsenic exclusively sorbed on the iron oxide nanoparticle surface. Generally, presented results highlight ferrate(VI) as one of the most promising candidates for advanced technologies of arsenic treatment mainly due to its environmentally friendly character, in situ applicability for treatment of both arsenites and arsenates, and contrary to all known competitive technologies, firmly bound part of arsenic preventing its leaching back to the environment. Moreover, As-containing ?-Fe2O3 nanoparticles are strongly magnetic allowing their separation from the environment by application of an external magnet. PMID:23451768

Prucek, Robert; Tu?ek, Ji?; Kola?璭, Jan; Filip, Jan; Maru嫜, Zden?k; Sharma, Virender K; Zbo?il, Radek

2013-04-01

54

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

NASA Astrophysics Data System (ADS)

?-Fe2O3 magnetic nanoparticles ranging in average diameter from 3to10nm were synthesized into a polystyrene resin matrix by an ion-exchange method and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), M飉sbauer spectroscopy, and SQUID magnetometry. The average particle size as determined from XRD and TEM was found to be strongly dependent upon the initial Fe valence state of the starting chloride salt(s) and on the number of steps that the salt introduction and ion-exchange process were repeated. Regardless of the initial Fe valence state and processing conditions, M飉sbauer spectroscopy confirmed that the Fe in the resulting nanoparticles existed only as Fe(III) ions and that ?-Fe2O3 was the only phase present. The values of the saturation magnetization at 5K were found to be dependent upon the processing conditions and ranged from 203to333emu/cm3 , which are significantly smaller than the bulk value (408emu/cm3) for ?-Fe2O3 . As expected, the nanoparticles exhibited superparamagnetic behavior with the magnetic moments becoming frozen with decreasing temperature as evidenced by the appearance of a six-line splitting in the M飉sbauer spectra, a bifurcation in the zero-field-cooled (ZFC) and field-cooled (FC) magnetizations, and an opening in the MV -vs- H hysteresis curves. The values of magnetic anisotropy constant (1.2-2.1106ergs/cm3) determined from the differences between the ZFC and FC magnetizations were found to be higher than the bulk value (1.1105ergs/cm3) for ?-Fe2O3 , and are probably due to surface effects. Likewise, the nanoparticle size distributions as deduced from the blocking temperature distribution function f(TB) based on fits to the difference in the ZFC and FC magnetization curves as well as from fits of the MV -vs- H curves in the superparamagnetic regime with a Langevin function indicate fairly broad distributions of particle sizes with the particle sizes being comparable to those deduced from XRD and TEM measurements. The smaller saturated magnetization values found for these nanoparticles combined with the non-zero slope of the high-field magnetization data suggests that these nanoparticles have a non-negligible surface layer of noncollinear spins surrounding a ferrimagnetically ordered ?-Fe2O3 core.

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

2007-07-01

55

Enhancement of photocurrent in ferroelectric films via the incorporation of narrow bandgap nanoparticles.  

PubMed

A novel nanostructured ferroelectric photovoltaic material, consisting of the ferroelectric lead zirconate titanate (PZT) film and Ag(2) O semiconductor nanoparticles of comparatively narrow bandgap, has demonstrated a remarkable enhancement in the photovoltaic effects and the highest light-electricity conversion efficiency among those PZT-based photodiodes previously reported. This work sheds light on the design and enhanced performance of new optoelectronic and solar energy devices. PMID:22278739

Yang, Xiaoluan; Su, Xiaodong; Shen, Mingrong; Zheng, Fengang; Xin, Yu; Zhang, Lu; Hua, Muchuan; Chen, Yajie; Harris, V G

2012-03-01

56

Tailoring acidity of HZSM-5 nanoparticles for methyl bromide dehydrobromination by Al and Mg incorporation  

PubMed Central

Three kinds of HZSM-5 nanoparticles with different acidity were tailored by impregnating MgO or varying Si/Al ratios. Both the textural and acidic properties of the as-prepared nanoparticles were characterized by nitrogen adsorption-desorption measurements, X-ray diffraction (XRD), scanning electron microscopy (SEM), ammonia temperature-programmed desorption (NH3-TPD) and Fourier transform infrared spectroscopy (FTIR or Py-FTIR). It was found that the intensity of Lewis acid sites with weak strength was enhanced by impregnating MgO or reducing Al concentration, and such an enhancement could be explained by the formation of Mg(OH)+ or charge unbalance of the MgO framework on the surface of HZSM-5 support. The effect of HZSM-5 nanoparticles' acidity on methyl bromide dehydrobromination as catalyst was evaluated. As the results, MgHZ-360 catalyst with the highest concentration of Lewis acid sites showed excellent stability, which maintained methyl bromide conversion of up 97% in a period of 400?h on stream. Coke characterization by BET measurements and TGA/DTA and GC/MS analysis revealed that polymethylated naphthalenes species were formed outside the channels of the catalyst with higher acid intensity and higher Br鷢sted acid concentration during the initial period of reaction, while graphitic carbon formed in the channels of catalyst with lower acid intensity and higher Lewis acid concentration during the stable stage. PMID:25328502

2014-01-01

57

A review of the dietary flavonoid, kaempferol on human health and cancer chemoprevention  

PubMed Central

Kaempferol is a polyphenol antioxidant found in fruits and vegetables. Many studies have described the beneficial effects of dietary kaempferol in reducing the risk of chronic diseases, especially cancer. Epidemiological studies have shown an inverse relationship between kaempferol intake and cancer. Kaempferol may help by augmenting the bodys antioxidant defense against free radicals, which promote the development of cancer. At the molecular level, kaempferol has been reported to modulate a number of key elements in cellular signal transduction pathways linked to apoptosis, angiogenesis, inflammation, and metastasis. Significantly, kaempferol inhibits cancer cell growth and angiognesis and induces cancer cell apoptosis, but on the other hand, kaempferol appears to preserve normal cell viability, in some cases exerting a protective effect. The aim of this review is to synthesize information concerning the extraction of kaempferol, as well as to provide insights into the molecular basis of its potential chemo-preventative activities, with an emphasis on its ability to control intracellular signaling cascades that regulate the aforementioned processes. Chemoprevention using nanotechnology to improve the bioavailability of kaempferol is also discussed. PMID:23497863

Chen, Allen Y.; Chen, Yi Charlie

2013-01-01

58

Kaempferol inhibits UVB-induced COX-2 expression by suppressing Src kinase activity  

PubMed Central

Ultraviolet (UV) radiation is the primary environmental risk factor in the development of nonmelanoma skin cancer, and UVB in particular promotes tumor growth through various signaling pathways. Kaempferol, a flavonoid with anti-inflammatory and anti-oxidative properties, has been studied as a chemopreventive agent; however, little is known regarding its effects on UVB-induced photo-carcinogenesis. Here, we examined the effect of kaempferol on UVB-induced skin inflammation. We found that kaempferol suppressed UVB-induced cyclooxygenase-2 (COX-2) protein expression in mouse skin epidermal JB6 P+ cells and attenuated the UVB-induced transcriptional activities of cox-2 and activator protein-1 (AP-1). Kaempferol attenuated the UVB-induced phosphorylation of several mitogen-activated protein kinases (MAPKs), including ERKs, p38, and JNKs, but had no effect on the phosphorylation of the upstream MAPK regulator Src. However, in vitro and ex vivo kinase assays demonstrated that kaempferol suppressed Src kinase activity. Furthermore, in vivo data from mouse skin support the idea that kaempferol suppresses UVB-induced COX-2 expression by blocking Src kinase activity. A pull-down assay revealed that kaempferol competes with ATP for direct binding to Src. Docking data suggest that kaempferol docks easily into the ATP-binding site of Src, which is located between the N and C lobes of the kinase domain. Taken together, these results suggest that kaempferol is a potent chemopreventive agent against skin cancer through its inhibitory interaction with Src. PMID:20599768

Lee, Kyung Mi; Lee, Ki Won; Jung, Sung Keun; Lee, Eun Jung; Heo, Yong-Seok; Bode, Ann M.; Lubet, Ronald A.; Lee, Hyong Joo; Dong, Zigang

2010-01-01

59

Study of incorporation of silver nanoparticles onto PE-g-PAAc nonwoven fabric by ?-irradiation for water treatment  

NASA Astrophysics Data System (ADS)

Polyethylene nonwoven (PE) fabric was grafted with acrylic acid (PE-g-PAAc) by the ?-ray pre-irradiation process. The effect of dose and acrylic acid concentration on the grafting degree was investigated. The dose of about 20-30 kGy, acrylic acid concentration of 20-30%, and the reaction time of about 2 h at 90 蚓 were selected as suitable parameters for grafting. The PE-g-PAAc fabric was then impregnated in colloidal silver nanoparticles (AgNPs) solution for incorporating AgNPs. The resultant PE-g-PAAc/AgNPs fabric containing 10,000 ppm AgNPs exhibits high antimicrobial activity (?>99%) against Escherichia coli in water. The release of silver into water filtrate determined by ICP-MS was less than 0.1 mg/L. The PE-g-PAAc/AgNPs fabric can be potentially applied for water and/or air treatment as an antimicrobial membrane filter.

Phu, Dang Van; Quoc, Le Anh; Duy, Nguyen Ngoc; Hien, Nguyen Quoc

2013-07-01

60

Rheological and tribological properties of carbon nanotube/thermoplastic nanocomposites incorporating inorganic fullerene-like WS2 nanoparticles.  

PubMed

The rheological and tribological properties of single-walled carbon nanotube (SWCNT)-reinforced poly(phenylene sulphide) (PPS) and poly(ether ether ketone) (PEEK) nanocomposites prepared via melt-extrusion were investigated. The effectiveness of employing a dual-nanofiller strategy combining polyetherimide (PEI)-wrapped SWCNTs with inorganic fullerene-like tungsten disulfide (IF-WS2) nanoparticles for property enhancement of the resulting hybrid composites was evaluated. Viscoelastic measurements revealed that the complex viscosity ?, storage modulus G', and loss modulus G? increased with SWCNT content. In the low-frequency region, G' and G? became almost independent of frequency at higher SWCNT loadings, suggesting a transition from liquid-like to solid-like behavior. The incorporation of increasing IF-WS2 contents led to a progressive drop in ? and G' due to a lubricant effect. PEEK nanocomposites showed lower percolation threshold than those based on PPS, ascribed to an improved SWCNT dispersion due to the higher affinity between PEI and PEEK. The SWCNTs significantly lowered the wear rate but only slightly reduced the coefficient of friction. Composites with both nanofillers exhibited improved wear behavior, attributed to the outstanding tribological properties of these nanoparticles and a synergistic reinforcement effect. The combination of SWCNTs with IF-WS2 is a promising route for improving the tribological and rheological performance of thermoplastic nanocomposites. PMID:22697425

D獯z-Pascual, Ana M; Naffakh, Mohammed; Marco, Carlos; Ellis, Gary

2012-07-12

61

Tuning cell adhesion by incorporation of charged silicate nanoparticles as cross-linkers to polyethylene oxide.  

PubMed

Controlling cell adhesion on a biomaterial surface is associated with the long-term efficacy of an implanted material. Here we connect the material properties of nanocomposite films made from PEO physically cross-linked with layered silicate nanoparticles (Laponite) to cellular adhesion. Fibroblast cells do not adhere to pure PEO, but they attach to silicate containing nanocomposites. Under aqueous conditions, the films swell and the degree of swelling depends on the nanocomposite composition and film structure. Higher PEO compositions do not support cell proliferation due to little exposed silicate surfaces. Higher silicate compositions do allow significant cell proliferation and spreading. These bio-nanocomposites have potential for the development of biomedical materials that can control cellular adhesion. PMID:20602416

Schexnailder, Patrick J; Gaharwar, Akhilesh K; Bartlett, Rush L; Seal, Brandon L; Schmidt, Gudrun

2010-12-01

62

Long-lasting in vivo and in vitro antibacterial ability of nanostructured titania coating incorporated with silver nanoparticles.  

PubMed

Although titanium (Ti) implants are widely used clinically, implant-associated bacterial infection is still one of the most serious complications in orthopedic surgery. Long-term antibacterial properties and the ability to inhibit biofilm formation are highly desirable to prevent implant associated infection. In this study, a controllable amount of silver (Ag) nanoparticles was incorporated into titanium oxide; or titanium, nanotubes (TiO? -NTs). The reliable release and long-term antibacterial function of Ag, in vivo and in vitro, and influence normal bone-implant integration from the Ag released from Ag-incorporated NTs in vivo have been studied to make them useable in clinical practice. In the current study, TiO? -NTs loaded with Ag (NT-Ag) exhibited strong antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA, ATCC43300) in vitro for 30 days, and the ability to penetrate the protein layer well. In addition, X-ray examination and 2-[(18)F]-fiuoro-2-deoxy-D-glucose positron emission tomography indicates that NT-Ag show extremely long antibacterial activity in vivo in a rat model. Furthermore, histomorphometric analysis demonstrated that satisfactory bio-integration can be expected. Our results indicate that NT-Ag has both simultaneous antimicrobial and excellent bio-integration properties, make it a promising therapeutic material for orthopedic application. PMID:24178451

Cheng, Hao; Li, Yong; Huo, Kaifu; Gao, Biao; Xiong, Wei

2014-10-01

63

A comparative study of two different approaches for the incorporation of silver nanoparticles into layer-by-layer films  

NASA Astrophysics Data System (ADS)

In this work, a comparative study about the incorporation of silver nanoparticles (AgNPs) into thin films is presented using two alternative methods, the in situ synthesis process and the layer-by-layer embedding deposition technique. The influence of several parameters such as color of the films, thickness evolution, thermal post-treatment, or distribution of the AgNPs along the coatings has been studied. Thermal post-treatment was used to induce the formation of hydrogel-like AgNPs-loaded thin films. Cross-sectional transmission electron microscopy micrographs, atomic force microscopy images, and UV-vis spectra reveal significant differences in the size and distribution of the AgNPs into the films as well as the maximal absorbance and wavelength position of the localized surface plasmon resonance absorption bands before and after thermal post-treatment. This work contributes for a better understanding of these two approaches for the incorporation of AgNPs into thin films using wet chemistry.

Rivero, Pedro Jose; Goicoechea, Javier; Matias, Ignacio Raul; Arregui, Francisco Javier

2014-06-01

64

A comparative study of two different approaches for the incorporation of silver nanoparticles into layer-by-layer films  

PubMed Central

In this work, a comparative study about the incorporation of silver nanoparticles (AgNPs) into thin films is presented using two alternative methods, the in situ synthesis process and the layer-by-layer embedding deposition technique. The influence of several parameters such as color of the films, thickness evolution, thermal post-treatment, or distribution of the AgNPs along the coatings has been studied. Thermal post-treatment was used to induce the formation of hydrogel-like AgNPs-loaded thin films. Cross-sectional transmission electron microscopy micrographs, atomic force microscopy images, and UV-vis spectra reveal significant differences in the size and distribution of the AgNPs into the films as well as the maximal absorbance and wavelength position of the localized surface plasmon resonance absorption bands before and after thermal post-treatment. This work contributes for a better understanding of these two approaches for the incorporation of AgNPs into thin films using wet chemistry. PMID:24982607

2014-01-01

65

Kaempferol regulates OPN-CD44 pathway to inhibit the atherogenesis of apolipoprotein E deficient mice  

SciTech Connect

Recent studies show that osteopontin (OPN) and its receptor cluster of differentiation 44 (CD44) are two pro-inflammatory cytokines contributing to the development of atherosclerosis. The objective of this study was to explore the inhibitory effect of kaempferol, a naturally occurring flavonoid compound, on atherogenesis and the mechanisms involved. The experiments were performed in aorta and plasma from C57BL/6J control and apolipoprotein E-deficient (ApoE{sup -/-}) mice treated or not with kaempferol (50 or 100 mg/kg, intragastrically) for 4 weeks. Kaempferol treatment decreased atherosclerotic lesion area, improved endothelium-dependent vasorelaxation, and increased the maximal relaxation value concomitantly with decrease in the half-maximum effective concentration, plasma OPN level, aortic OPN expression, and aortic CD44 expression in ApoE{sup -/-} mice. In addition, treatment with kaempferol also significantly decreased reactive oxygen species production in mice aorta. The present results suggest that kaempferol regulates OPN-CD44 pathway to inhibit the atherogenesis of ApoE{sup -/-} mice. -- Graphical abstract: Kaempferol regulates OPN-CD44 pathway to inhibit the atherogenesis of ApoE{sup -/-} mice. Highlights: Black-Right-Pointing-Pointer OPN-CD44 pathway plays a critical role in the development of atherosclerosis. Black-Right-Pointing-Pointer We examine lesion area, OPN and CD44 changes after kaempferol treatment. Black-Right-Pointing-Pointer Kaempferol treatment decreased atherosclerotic lesion area in ApoE{sup -/-} mice. Black-Right-Pointing-Pointer Kaempferol treatment decreased aortic OPN and CD44 expressions in ApoE{sup -/-} mice. Black-Right-Pointing-Pointer Kaempferol regulates OPN-CD44 pathway to inhibit the atherogenesis.

Xiao, Hong-Bo, E-mail: xhbzhb@yahoo.com [College of Veterinary Medicine, Hunan Agricultural University, Changsha 410128 (China)] [College of Veterinary Medicine, Hunan Agricultural University, Changsha 410128 (China); Lu, Xiang-Yang; Sun, Zhi-Liang [Hunan Agricultural University, Changsha 410128 (China)] [Hunan Agricultural University, Changsha 410128 (China); Zhang, Heng-Bo [Furong District Red Cross Hospital, Changsha 410126 (China)] [Furong District Red Cross Hospital, Changsha 410126 (China)

2011-12-15

66

Direct Incorporation of Lipophilic Nanoparticles into Monodisperse Perfluorocarbon Nanodroplets via Solvent Dissolution from Microfluidic-Generated Precursor Microdroplets.  

PubMed

Multifunctional medical agents based on imaging or therapy nanoparticles (NPs) incorporated into perfluorocarbon (PFC) droplets are promising new agents for cancer detection and treatment. For the first time, monodisperse PFC nanodroplets labeled with NPs have been produced. Lipophilic, as-synthesized, hydrocarbon-stabilized NPs are directly miscibilized into lipophobic PFCs using a removable cosolvent, diethyl ether (DEE), which eliminates the need of the typical time-consuming and expertise-specific NP surface modification steps previously required for NP incorporation into PFCs. This NP-DEE/PFC solution is then used to synthesize monodisperse, micrometer-scale, DEE-infused NP-PFC precursor droplets in water using microfluidics. After precursor microdroplet generation, the DEE cosolvent is removed by dissolution and evaporation, resulting in dramatically smaller, monodisperse, NP-labeled nanodroplets, with final droplet sizes far smaller than the minimum droplet size limit of the microfluidic system, and easily controlled by the amount of DEE mixed in the PFC phase prior to precursor droplet synthesis. Using this technique, unmodified lipophilic quantum dot (QD) NPs were integrated into monodisperse and PFC nanodroplets 165 times smaller in volume than the precursor microdroplets, with dimensions down to 470 nm. The final droplet sizes scaled with the PFC concentrations in the precursor microdroplets, and the QDs remain localized within the droplets after DEE is removed from the system. This method is robust and versatile, and it comprises a platform technology for other unmodified lipophilic NPs and molecules to be incorporated into different types of PFC droplets for the production of new NP-PFC hybrid agents for medical imaging and therapy applications. PMID:25188556

Seo, Minseok; Matsuura, Naomi

2014-10-28

67

Chiral recognition of proteins having L-histidine residues on the surface with lanthanide ion complex incorporated-molecularly imprinted fluorescent nanoparticles.  

PubMed

In this study, lanthanide ion complex incorporated molecularly imprinted fluorescent nanoparticles were synthesized. A combination of three novel approaches was applied for the purpose. First, lanthanide ions [Terbium(III)] were complexed with N-methacryloyl-L-histidine (MAH), polymerizable derivative of L-histidine amino acid, in order to incorporate the complex directly into the polymeric backbone. At the second stage, L-histidine molecules imprinted nanoparticles were utilized instead of whole protein imprinting in order to avoid whole drawbacks such as fragility, complexity, denaturation tendency, and conformation dependency. At the third stage following the first two steps mentioned above, imprinted L-histidine was coordinated with cupric ions [Cu(II)] to conduct the study under mild conditions. Then, molecularly imprinted fluorescent nanoparticles synthesized were used for L-histidine adsorption from aqueous solution to optimize conditions for adsorption and fluorimetric detection. Finally, usability of nanoparticles was investigated for chiral biorecognition using stereoisomer, D-histidine, racemic mixture, D,L-histidine, proteins with surface L-histidine residue, lysozyme, cytochrome C, or without ribonuclease A. The results revealed that the proposed polymerization strategy could make significant contribution to the solution of chronic problems of fluorescent component introduction into polymers. Additionally, the fluorescent nanoparticles reported here could be used for selective separation and fluorescent monitoring purposes. PMID:23706231

Uzun, Lokman; Uzek, Recep; Senel, Serap; Say, Ridvan; Denizli, Adil

2013-08-01

68

Incorporation of (57)Fe-isotopically enriched in apoferritin: formation and characterization of isotopically enriched Fe nanoparticles for metabolic studies.  

PubMed

The use of (57)Fe-isotopically enriched ferritin for the accurate measurement of Fe?:?ferritin ratios is proposed for metabolic studies. Thus, the synthesis of (57)Fe-isotopically enriched ferritin from horse apo-ferritin and isotopically enriched (NH4)2(57)Fe(ii)(SO4)2 (Mohr's salt) is conducted. Size exclusion chromatography on-line with UV-VIS absorption (at 380 nm) is used in order to monitor the loading process of apo-ferritin. These studies revealed that the Fe-incorporation process involves also the formation of protein aggregates (oligomers) showing higher molecular mass than ferritin. A final optimized protocol involving incubation of the synthesized standard with guanidine hydrochloride (pH 3.5) has provided the best conditions for maintaining a stable protein structure without aggregates. Such (57)Fe-isotopically enriched ferritin was characterized and contained an average of 2200 atoms of Fe per mole of ferritin. The evaluation of the Fe-core after saturation with (57)Fe by Transmission Electron Microscopy (TEM) has revealed the formation of (57)Fe nanoparticles with a similar diameter to that of the commercial Fe-containing ferritin, confirming the process of Fe uptake, oxidation and mineralization within the protein cavity. The synthesized (57)Fe-ferritin shows great potential as a nanometabolic tracer to study the kinetics of Fe release in the cases of iron metabolic disorders. PMID:25170527

Konz, T; Montes-Bay鏮, M; Sanz-Medel, A

2014-09-29

69

Kaempferol glycosides and cardenolide glycosides, cytotoxic constituents from the seeds of Draba nemorosa (Brassicaceae)  

Microsoft Academic Search

Bioassay-directed fractionation of a methanolic extract from the seeds of Draba nemorosa (Brassicaceae) led to isolation of a new flavonol glycoside, drabanemoroside (5, kaempferol 3-O-?-L-rhamnopyranosyl-(1?2)-?-L-arabinopyranose) along with four known flavonoid derivatives (14), four cardenolide glycosides (69). Kaempferol glycosides 2 and 5 showed strong cytotoxicity against human small lung cancer cell line A549 and melanoma SK-Mel-2 with an IC50 of 0.5

Surk-Sik Moon; Aziz Abdur Rahman; Maniruzzaman Manir; V. S. Jamal Ahamed

2010-01-01

70

ZnO nanoparticle incorporated nanostructured metallic titanium for increased mesenchymal stem cell response and antibacterial activity  

NASA Astrophysics Data System (ADS)

Recent trends in titanium implants are towards the development of nanoscale topographies that mimic the nanoscale properties of bone tissue. Although the nanosurface promotes the integration of osteoblast cells, infection related problems can also occur, leading to implant failure. Therefore it is imperative to reduce bacterial adhesion on an implant surface, either with or without the use of drugs/antibacterial agents. Herein, we have investigated two different aspects of Ti surfaces in inhibiting bacterial adhesion and concurrently promoting mammalian cell adhesion. These include (i) the type of nanoscale topography (Titania nanotube (TNT) and Titania nanoleaf (TNL)) and (ii) the presence of an antibacterial agent like zinc oxide nanoparticles (ZnOnp) on Ti nanosurfaces. To address this, periodically arranged TNT (80-120 nm) and non-periodically arranged TNL surfaces were generated by the anodization and hydrothermal techniques respectively, and incorporated with ZnOnp of different concentrations (375 ?M, 750 ?M, 1.125 mM and 1.5 mM). Interestingly, TNL surfaces decreased the adherence of staphylococcus aureus while increasing the adhesion and viability of human osteosarcoma MG63 cell line and human mesenchymal stem cells, even in the absence of ZnOnp. In contrast, TNT surfaces exhibited an increased bacterial and mammalian cell adhesion. The influence of ZnOnp on these surfaces in altering the bacterial and cell adhesion was found to be concentration dependent, with an optimal range of 375-750 ?M. Above 750 ?M, although bacterial adhesion was reduced, cellular viability was considerably affected. Thus our study helps us to infer that nanoscale topography by itself or its combination with an optimal concentration of antibacterial ZnOnp would provide a differential cell behavior and thereby a desirable biological response, facilitating the long term success of an implant.

Elizabeth, Elmy; Baranwal, Gaurav; Krishnan, Amit G.; Menon, Deepthy; Nair, Manitha

2014-03-01

71

ZnO nanoparticle incorporated nanostructured metallic titanium for increased mesenchymal stem cell response and antibacterial activity.  

PubMed

Recent trends in titanium implants are towards the development of nanoscale topographies that mimic the nanoscale properties of bone tissue. Although the nanosurface promotes the integration of osteoblast cells, infection related problems can also occur, leading to implant failure. Therefore it is imperative to reduce bacterial adhesion on an implant surface, either with or without the use of drugs/antibacterial agents. Herein, we have investigated two different aspects of Ti surfaces in inhibiting bacterial adhesion and concurrently promoting mammalian cell adhesion. These include (i) the type of nanoscale topography (Titania nanotube (TNT) and Titania nanoleaf (TNL)) and (ii) the presence of an antibacterial agent like zinc oxide nanoparticles (ZnOnp) on Ti nanosurfaces. To address this, periodically arranged TNT (80-120nm) and non-periodically arranged TNL surfaces were generated by the anodization and hydrothermal techniques respectively, and incorporated with ZnOnp of different concentrations (375?M, 750?M, 1.125mM and 1.5mM). Interestingly, TNL surfaces decreased the adherence of staphylococcus aureus while increasing the adhesion and viability of human osteosarcoma MG63 cell line and human mesenchymal stem cells, even in the absence of ZnOnp. In contrast, TNT surfaces exhibited an increased bacterial and mammalian cell adhesion. The influence of ZnOnp on these surfaces in altering the bacterial and cell adhesion was found to be concentration dependent, with an optimal range of 375-750?M. Above 750?M, although bacterial adhesion was reduced, cellular viability was considerably affected. Thus our study helps us to infer that nanoscale topography by itself or its combination with an optimal concentration of antibacterial ZnOnp would provide a differential cell behavior and thereby a desirable biological response, facilitating the long term success of an implant. PMID:24561517

Elizabeth, Elmy; Baranwal, Gaurav; Krishnan, Amit G; Menon, Deepthy; Nair, Manitha

2014-03-21

72

CdS nanoparticles incorporated onion-like mesoporous silica films: Ageing-induced large stokes shifted intense PL emission  

NASA Astrophysics Data System (ADS)

CdS nanoparticles (NPs) were generated in onion-like ordered mesoporous SiO2 films through a modified sol-gel process using P123 as a structure directing agent. Initially Cd2+ doped (12 equivalent mol% with respect to the SiO2) mesoporous SiO2 films were prepared on glass substrate. These films after heat-treatment at 350 蚓 in air yielded transparent mesoporous SiO2 films having hexagonally ordered onion-like pore channels embedded with uniformly dispersed CdO NPs. The generated CdO NPs were transformed into CdS NPs after exposing the films in H2S gas at 200 蚓 for 2 h. The as-prepared CdS NPs incorporated mesoporous SiO2 films (transparent and bright yellow in color) showed a band-edge emission at 485 nm and a weak surface defect related emission at 530 nm. During ageing of the films in ambient condition the band-edge emission gradually weakened with time and almost disappeared after about 15 days with concomitant increase of defect related strong surface state emission band near 615 nm. This transformation was related to the decay of initially formed well crystalline CdS to relatively smaller and weakly crystalline CdS NPs with surface defects due to gradual oxidation of surface sulfide. At this condition the embedded CdS NPs show large Stokes shifted (180 nm) intense broad emission which could be useful for luminescent solar concentrators. The detailed process was monitored by UV-Visible, FTIR and Raman spectroscopy, XPS, XRD and TEM studies. The evolution of photoluminescence (PL) and life times of CdS/SiO2 films were monitored with respect to the ageing time.

Mishra, Manish Kr; Mandal, Abhijit; Saha, Jony; De, Goutam

2013-10-01

73

Kaempferol enhances intestinal barrier function through the cytoskeletal association and expression of tight junction proteins in Caco-2 cells.  

PubMed

Kaempferol, a natural flavonoid present in fruits, vegetables, and teas, provides beneficial effects for human health. We investigated the promotive effect of kaempferol on tight junction (TJ) barrier integrity in human intestinal Caco-2 cell monolayers. Transepithelial electrical resistance (TER; a TJ integrity marker) across the monolayers rapidly and markedly increased during the first 6 h after kaempferol administration and remained elevated until 48 h without any changes in the lucifer yellow or dextran fluxes. Immunoblot analysis demonstrated that kaempferol promoted the actin cytoskeletal association of the TJ proteins, zonula occludens (ZO)-1, ZO-2, occludin, claudin-1, claudin-3, and claudin-4, which was associated with the increase in TER. Kaempferol-mediated ZO-2 and claudin-4 expression was relatively smaller or occurred later than the kaempferol-promoted cytoskeletal association. Confocal microscopy showed that kaempferol-induced assembly of occludin and claudin-3 occurred at the TJ at 6 h postadministration. Extraction of cholesterol with methyl-?-cyclodextrin suppressed the kaempferol-mediated increase in TER. Sucrose density gradient centrifugation showed that the kaempferol treatment increased the TJ protein distributions in the cholesterol-rich lipid microdomain fraction. Taken together, these results indicate that the membrane lipid microdomain is involved in the kaempferol-mediated promotion of TJ protein assembly and intestinal TJ integrity. PMID:21068182

Suzuki, Takuya; Tanabe, Soichi; Hara, Hiroshi

2011-01-01

74

Kaempferol inhibits VEGF expression and in vitro angiogenesis through a novel ERK-NF?B-cMyc-p21 pathway  

PubMed Central

Kaempferol has been reported to reduce the risk of ovarian cancer, but the mechanism is not completely understood. In this study, we tend to expand our understanding on how kaempferol regulates VEGF expression and angiogenesis in ovarian cancer cells. We timed VEGF secretion, and studied in-vitro angiogenesis by kaempferol treatment. Gene expression was examined by qRT-PCR, ELISA, Western Blotting, or luciferase assay, and pathways were examined by manipulating genetic components with plasmid or siRNA transfection. It was found that kaempferol time-dependently inhibited VEGF secretion, and suppressed in-vitro angiogenesis. Kaempferol down-regulated ERK phosphorelation as well as NF?B and cMyc expression, but promoted p21 expression. Examination of relationship between these genes suggested a novel ERK-NF?B-cMyc-p21-VEGF pathway, which accounts for kaempferols angioprevention effects in ovarian cancer cells. This data supplements our comprehension of the mechanisms behind kaempferols biological influence in ovarian cancer cells, and better characterized kaempferol toward chemoprevention. PMID:21927533

Luo, Haitao; Rankin, Gary O.; Juliano, Noelle; Jiang, Bing-Hua; Chen, Yi Charlie

2011-01-01

75

Improved performance of poly(3,4-ethylenedioxythiophene):poly(stylene sulfonate)/n-Si hybrid solar cell by incorporating silver nanoparticles  

NASA Astrophysics Data System (ADS)

We report an enhancement in the efficiency of poly(3,4-ethylenedioxythiophene):poly(stylene sulfonate) (PEDOT:PSS)/n-Si hybrid solar cell by incorporating silver nanoparticles (AgNPs) with PEDOT:PSS. AgNPs were prepared by reducing silver nitrate in green-tea solution, which showed characteristic absorption peak due to the surface plasmonic resonance effect. AgNPs incorporated PEDOT:PSS/n-Si hybrid device shows power conversion efficiency (?) of 10.21%, which is comparatively higher to the performance of pristine device without AgNPs. Here, we noticed that incorporation of AgNPs decreases sheet resistance and enlarged surface roughness of PEDOT:PSS film for the efficient collection of charges, rather than plasmonic effect.

Khatri, Ishwor; Liu, Qiming; Ueno, Keiji; Shirai, Hajime

2014-11-01

76

Protective and detrimental effects of kaempferol in rat H4IIE cells: Implication of oxidative stress and apoptosis  

SciTech Connect

Flavonoids are ubiquitous substances in fruits and vegetables. Among them, the flavonol kaempferol contributes up to 30% of total dietary flavonoid intake. Flavonoids are assumed to exert beneficial effects on human health, e.g., anticancer properties. For this reason, they are used in food supplements at high doses. The aim of this project was to determine the effects of kaempferol on oxidative stress and apoptosis in H4IIE rat hepatoma cells over a broad concentration range. Kaempferol is rapidly taken up and glucuronidated by H4IIE cells. The results demonstrate that kaempferol protects against H{sub 2}O{sub 2}-induced cellular damage at concentrations which lead to cell death and DNA strand breaks in the absence of H{sub 2}O{sub 2}-mediated oxidative stress. Preincubation with 50 {mu}M kaempferol exerts protection against the loss of cell viability induced by 500 {mu}M H{sub 2}O{sub 2} (2 h) while the same concentration of kaempferol reduces cell viability by 50% in the absence of H{sub 2}O{sub 2} (24 h). Preincubation with 50 {mu}M kaempferol ameliorates the strong DNA damage induced by 500 {mu}M H{sub 2}O{sub 2} while 50 {mu}M kaempferol leads to a significant increase of DNA breakage in the absence of H{sub 2}O{sub 2}. Preincubation with 50 {mu}M kaempferol reduces H{sub 2}O{sub 2}-mediated caspase-3 activity by 40% (4 h) while the same concentration of kaempferol leads to the formation of a DNA ladder in the absence of H{sub 2}O{sub 2} (24 h). It is concluded that the intake of high dose kaempferol in food supplements may not be advisable because in our cellular model protective kaempferol concentrations can also induce DNA damage and apoptosis by themselves.

Niering, Petra [Institute of Toxicology, Heinrich-Heine-University, PO Box 101007, 40001 Duesseldorf (Germany); Michels, Gudrun [Institute of Toxicology, Heinrich-Heine-University, PO Box 101007, 40001 Duesseldorf (Germany); Waetjen, Wim [Institute of Toxicology, Heinrich-Heine-University, PO Box 101007, 40001 Duesseldorf (Germany)]. E-mail: wim.waetjen@uni-duesseldorf.de; Ohler, Sandra [Institute of Toxicology, Heinrich-Heine-University, PO Box 101007, 40001 Duesseldorf (Germany); Steffan, Baerbel [Institute of Pharmaceutical Biology and Biotechnology, Heinrich-Heine-University, Universitaetsstrasse 1, 40225 Duesseldorf (Germany); Chovolou, Yvonni [Institute of Toxicology, Heinrich-Heine-University, PO Box 101007, 40001 Duesseldorf (Germany); Kampkoetter, Andreas [Institute of Toxicology, Heinrich-Heine-University, PO Box 101007, 40001 Duesseldorf (Germany); Proksch, Peter [Institute of Pharmaceutical Biology and Biotechnology, Heinrich-Heine-University, Universitaetsstrasse 1, 40225 Duesseldorf (Germany); Kahl, Regine [Institute of Toxicology, Heinrich-Heine-University, PO Box 101007, 40001 Duesseldorf (Germany)

2005-12-01

77

Effects of magnetic nanoparticle-incorporated human bone marrow-derived mesenchymal stem cells exposed to pulsed electromagnetic fields on injured rat spinal cord.  

PubMed

Transplanting mesenchymal stem cells into injured lesions is currently under study as a therapeutic approach for spinal cord injury. In this study, the effects of a pulsed electromagnetic field (PEMF) on injured rat spinal cord were investigated in magnetic nanoparticle (MNP)-incorporated human bone marrow-derived mesenchymal stem cells (hBM-MSCs). A histological analysis revealed significant differences in MNP-incorporated cell distribution near the injured site under the PEMF in comparison with that in the control group. We confirmed that MNP-incorporated cells were widely distributed in the lesions under PEMF. The results suggest that MNP-incorporated hBM-MSCs were guided by the PEMF near the injured site, and that PEMF exposure for 8 H per day over 4 weeks promoted behavioral recovery in spinal cord injured rats. The results show that rats with MNP-incorporated hBM-MSCs under a PEMF were more effective on the Basso, Beattie, and Bresnahan behavioral test and suggest that the PEMF enhanced the action of transplanted cells for recovery of the injured lesion. PMID:24033637

Cho, Hyunjin; Choi, Yun-Kyong; Lee, Dong Heon; Park, Hee Jung; Seo, Young-Kwon; Jung, Hyun; Kim, Soo-Chan; Kim, Sung-Min; Park, Jung-Keug

2013-01-01

78

Hepatocyte growth factor incorporated chitosan nanoparticles augment the differentiation of stem cell into hepatocytes for the recovery of liver cirrhosis in mice  

Microsoft Academic Search

BackgroundShort half-life and low levels of growth factors in the niche of injured microenvironment necessitates the exogenous and sustainable\\u000a delivery of growth factors along with stem cells to augment the regeneration of injured tissues.\\u000a \\u000a \\u000a \\u000a \\u000a MethodsHere, recombinant human hepatocyte growth factor (HGF) was incorporated into chitosan nanoparticles (CNP) by ionic gelation\\u000a method and studied for its morphological and physiological characteristics. Cirrhotic

Sivasami Pulavendran; Chellan Rose; Asit Baran Mandal

2011-01-01

79

Development of Nanoparticles Incorporating a Novel Liposomal Membrane Destabilization Peptide for Efficient Release of Cargos into Cancer Cells  

PubMed Central

In anti-cancer therapy mediated by a nanoparticle-based drug delivery system (DDS), overall efficacy depends on the release efficiency of cargos from the nanoparticles in the cancer cells as well as the specificity of delivery to tumor tissue. However, conventional liposome-based DDS have no mechanism for specifically releasing the encapsulated cargos inside the cancer cells. To overcome this barrier, we developed nanoparticles containing a novel liposomal membrane destabilization peptide (LMDP) that can destabilize membranes by cleavage with intramembranous proteases on/in cancer cells. Calcein encapsulated in liposomes modified with LMDP (LMDP-lipo) was effectively released in the presence of a membrane fraction containing an LMDP-cleavable protease. The release was inhibited by a protease inhibitor, suggesting that LMDP-lipo could effectively release its cargo into cells in response to a cancer-specific protease. Moreover, when LMDP-lipo contained fusogenic lipids, the release of cargo was accelerated, suggesting that the fusion of LMDP-lipo with cellular membranes was the initial step in the intracellular delivery. Time-lapse microscopic observations showed that the release of cargo from LMDP-lipo occurred immediately after association of LMDP-lipo with target cells. Consequently, LMDP-lipo could be a useful nanoparticle capable of effective release of cargos specifically into targeted cancer cells. PMID:25343714

Ohgita, Takashi; Kogure, Kentaro

2014-01-01

80

Pollination- or Wound-Induced Kaempferol Accumulation in Petunia Stigmas Enhances Seed Production.  

PubMed Central

Flavonols are essential for pollen germination and tube growth in petunia and can be supplied by either the pollen or stigma at pollination. HPLC analysis and a sensitive bioassay demonstrated that both pollination and wounding induce flavonol accumulation, especially kaempferol, in the outer cell layers and exudate of the stigma. Pollination and wounding induced nearly identical flavonol kinetics and patterns of accumulation in the same target tissue, suggesting that they share elements of a common signal transduction pathway. The wound response was systemic, because kaempferol accumulated in the stigma when distal tissues, such as the corolla, stamens, or sepals, were wounded. We have exploited the germination requirement for flavonols and the high level of kaempferol that accumulates after wounding to enhance plant fecundity. Seed set was significantly increased by mechanically wounding the corolla and stamens prior to the application of pollen to the stigma. A reproductive role for a plant secondary metabolite and the specific function of stigmatic kaempferol are discussed from an evolutionary perspective. PMID:12244218

Vogt, T.; Pollak, P.; Tarlyn, N.; Taylor, L. P.

1994-01-01

81

Kaempferol 7- O-rhamnoside-4?- O-glucoside from Pteridium aquilinum  

Microsoft Academic Search

A new flavonol glycoside from aerial parts of Pteridium aquilinum was identified as kaempferol 7-O-rhamnoside-4?-O-glucoside by chemical and spectral methods. In addition a mixture of quercetin 3-O-fructoside and isoquercitrin was found in this plant material.

Filippo Imperato

1998-01-01

82

nanoparticles  

NASA Astrophysics Data System (ADS)

In this paper, we report the observation of intrinsic room temperature ferromagnetism in pure La2O3 nanoparticles. Magnetism measurement indicates that all of the samples exhibit room temperature ferromagnetism and the saturation magnetization for the samples decreases with the increase in annealing temperature from 700 to 1,000 蚓. X-ray photoelectron spectroscopy identifies the presence of oxygen vacancies in the La2O3 nanoparticles. The fitting results of the O 1 s spectrum indicate that the variation of the oxygen vacancy concentration is in complete agreement with the change of the saturation magnetization. It is also found that the saturation magnetization of the La2O3 nanoparticles can be tuned by post-annealing in argon or oxygen atmosphere. These results suggest that the oxygen vacancies are largely responsible for the room temperature ferromagnetism in pure La2O3 nanoparticles.

Xu, Qiang; Gao, Daqiang; Zhang, Jing; Yang, Zhaolong; Zhang, Zhipeng; Rao, Jinwei; Xue, Desheng

2014-09-01

83

Characterization of Silicon Nanoparticles Formed from a Fluidized Bed Reactor and Their Incorporation onto Metal-Coated Carbon Fibers  

NASA Astrophysics Data System (ADS)

Enhancing the light trapping using nonwoven arrays of fibers has the potential to improve the photocurrent of silicon solar cells. In this work, amorphous and crystalline Si nanopowders (30-300 nm) were embedded in carbon fibers and fixed in place with electrodeposited nickel. Scanning and transmission electron microscopy techniques have been used to study the morphology of the Si particles and their interactions with the coatings. Two types of nanoparticles are identified, homogeneous nucleated particles (amorphous particles with some crystalline regions) and attrition particles (mostly crystalline products formed from fracture of particles as they grow in a fluidized bed reactor). Using the Brunauer-Emmett-Teller (BET) technique, the surface area and the pore diameter of these agglomerated Si nanoparticles were calculated to be 6.4 m2/g and 9.8 nm, respectively. After embedding the Si particles into the carbon matrix with the metal coatings, the electrical resistivity decreases, suggesting it is possible to enhance the light extraction of silicon solar cells using Si nanoparticles.

Zbib, Mohamad B.; Sahaym, Uttara; Bahr, David F.

2014-01-01

84

Thixoforming of A356/SiC and A356/TiB2 Nanocomposites Fabricated by a Combination of Green Compact Nanoparticle Incorporation and Ultrasonic Treatment of the Melted Compact  

NASA Astrophysics Data System (ADS)

Thixoforming is a type of semi-solid processing which is based on forming metals in the semi-solid state rather than fully liquid or solid state. There have been no reports of the thixoforming of nanocomposites in the literature. The incorporation of ceramic nanoparticles into liquid metals is a challenging task for the fabrication of metal matrix nanocomposites due to their large surface-to-volume ratio and poor wettability. Previous research work by a number of workers has highlighted the challenges with the incorporation of nanoparticles into liquid aluminum alloy. In the present study, SiC and TiB2 nanoparticles with an average diameter between 20 and 30 nm were firstly incorporated into green compacts by a powder forming route, and then the compacts were melted and treated ultrasonically. The microstructural studies reveal that the engulfment and relatively effective distribution of the nanoparticles into the melt were achieved. The hardness was considerably improved with only 0.8 wt pct addition of the nanoparticles. The nanocomposites were successfully thixoformed at a solid fraction between 0.65 and 0.70. The microstructures, hardness, and tensile mechanical properties of the thixoformed nanocomposites were investigated and compared with those of the as-received A356 and thixoformed A356 alloys. The tensile properties of the thixoformed nanocomposites were significantly enhanced compared to thixoformed A356 alloy without reinforcement, indicating the strengthening effects of the nanoparticles.

Kandemir, Sinan; Atkinson, Helen V.; Weston, David P.; Hainsworth, Sarah V.

2014-08-01

85

Regulation of heme oxygenase-1 expression and MAPK pathways in response to kaempferol and rhamnocitrin in PC12 cells  

SciTech Connect

Oxidative stress has been considered as a major cause of cellular injuries in a variety of clinical abnormalities, especially neural diseases. Our aim of research is to investigate the protective effects and mechanisms of kaempferol and rhamnocitrin (kaempferol-7-methyl ether) on oxidative damage in rat pheochromocytoma PC12 cells induced by a limited supply of serum and hydrogen peroxide (H{sub 2}O{sub 2}). The current result demonstrated that kaempferol protected PC12 cells from serum deprivation-induced apoptosis. Pretreatment of cells with kaempferol also diminished intracellular generation of reactive oxygen species (ROS) in response to H{sub 2}O{sub 2} and strongly elevated cell viability. RT-Q-PCR and Western blotting revealed that kaempferol and rhamnocitrin significantly induced heme oxygenase (HO)-1 gene expression. Addition of zinc protoporphyrin (Znpp), a HO-1 competitive inhibitor, significantly attenuated their protective effects in H{sub 2}O{sub 2}-treated cells, indicating the vital role of HO-1 in cell resistance to oxidative injury. While investigating the signaling pathways responsible for HO-1 induction, we observed that kaempferol induced sustained extracellular signal-regulated protein kinase 1/2 (ERK1/2) in PC12 cells grown in low serum medium; while rhamnocitrin only stimulated transient ERK cascade. Addition of U0126, a highly selective inhibitor of MEK1/2, which is upstream of ERK1/2, had no effect on kaempferol- or rhamnocitrin-induced HO-1 mRNA expression, indicating no direct cross-talk between these two pathways. Furthermore, both kaempferol and rhamnocitrin were able to persistently attenuate p38 phosphorylation. Taking together, the above findings suggest that kaempferol and rhamnocitrin can augment cellular antioxidant defense capacity, at least in part, through regulation of HO-1 expression and MAPK signal transduction.

Hong, J.-T. [Department of Biotechnology, Chia-Nan University of Pharmacy and Science, Tainan 717, Taiwan (China); Yen, J.-H. [Department of Molecular Biology and Human Genetics, Tzu Chi University, Hualien 970, Taiwan (China); Wang Lisu [Department of Food Science and Technology, Chia-Nan University of Pharmacy and Science, Tainan 717, Taiwan (China); Department of Environmental and Occupational Health, Medical College, Cheng-Kung University, Tainan 701, Taiwan (China); Lo, Y.-H. [Department of Biotechnology, Chia-Nan University of Pharmacy and Science, Tainan 717, Taiwan (China); Chen, Z.-T. [Department of Medicinal Chemistry, Chia-Nan University of Pharmacy and Science, Tainan 717, Taiwan (China); Wu, M.-J. [Department of Biotechnology, Chia-Nan University of Pharmacy and Science, Tainan 717, Taiwan (China)], E-mail: imwu@mail.chna.edu.tw

2009-05-15

86

The role of size and coating in Au nanoparticles incorporated into bi-component polymeric thin-film transistors  

NASA Astrophysics Data System (ADS)

We describe the effect of blending poly(3-hexylthiophene) (P3HT) with Au nanoparticles (AuNPs) on the performance of organic thin-film transistors. To this end we have used AuNPs of two different sizes coated with chemisorbed SAMs of oligophenyl-thiols possessing increasing lengths. The electrical characteristics of the hybrid materials revealed changes in the field-effect mobility depending primarily on the AuNP size, as a result of the variable energy level of the coated metallic nanocluster and by the degree of modification of the P3HT crystalline structure.We describe the effect of blending poly(3-hexylthiophene) (P3HT) with Au nanoparticles (AuNPs) on the performance of organic thin-film transistors. To this end we have used AuNPs of two different sizes coated with chemisorbed SAMs of oligophenyl-thiols possessing increasing lengths. The electrical characteristics of the hybrid materials revealed changes in the field-effect mobility depending primarily on the AuNP size, as a result of the variable energy level of the coated metallic nanocluster and by the degree of modification of the P3HT crystalline structure. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr00076e

Mosciatti, Thomas; Orgiu, Emanuele; Raimondo, Corinna; Samor, Paolo

2014-04-01

87

nanoparticles  

NASA Astrophysics Data System (ADS)

Undoped and Zn-doped TiO2 nanoparticles were synthesized by the sol gel method. The dopant (Zn) was taken at 0.1, 0.2, 0.5, 0.7, and 1.0 mol%. The initial precursors were titanium tetraisopropoxide and zinc acetate. The samples were characterized by X-ray powder diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, and UV-vis diffuse reflectance. The photocatalytic activity of the prepared nanoparticles was studied by observing their role in degradation of two azo dyes, i.e., Eriochrome Black T and Methyl Red under UV-visible light. The results revealed that Zn-doped TiO2 nanoparticles exhibited better degradation as compared to undoped TiO2 nanoparticles. In this study, 0.7 mol% Zn-doped TiO2 showed highest photocatalytic activity. Doping of Zn allowed better separation of electron-hole pairs which results in increased oxidation and reduction reactions.

Singla, Pooja; Sharma, Manoj; Pandey, O. P.; Singh, K.

2014-07-01

88

Kaempferol glycosides and cardenolide glycosides, cytotoxic constituents from the seeds of Draba nemorosa (Brassicaceae).  

PubMed

Bioassay-directed fractionation of a methanolic extract from the seeds of Draba nemorosa (Brassicaceae) led to isolation of a new flavonol glycoside, drabanemoroside (5, kaempferol 3-O-alpha-L-rhamnopyranosyl-(1-->2)-alpha-L-arabinopyranose) along with four known flavonoid derivatives (1-4), four cardenolide glycosides (6-9). Kaempferol glycosides 2 and 5 showed strong cytotoxicity against human small lung cancer cell line A549 and melanoma SK-Mel-2 with an IC(50) of 0.5 microg/mL and 1.9 microg/mL, respectively. Cardenolide glycosides 6-9 showed potent cytotoxicity (A549) in the range of 0.01-0.032 microg/mL. Their structures were characterized based on spectroscopic data (2D NMR, HRTOFMS, IR, and UV) and comparison of literature values. The carbohydrate units were also confirmed by comparing the hydrolysate of 5 with authentic monosaccharides. PMID:20803119

Moon, Surk-Sik; Rahman, Md Aziz Abdur; Manir, Md Maniruzzaman; Jamal Ahamed, V S

2010-08-01

89

Possible mechanism(s) behind recently observed effects of incorporating gold nanoparticles into a polymer-dispersed liquid crystal  

NASA Astrophysics Data System (ADS)

Recently we reported that addition of relatively small concentrations of about 14-nm diameter gold nanoparticles (Au NPs) to a polymer-dispersed liquid crystal (PDLC) produces rather large changes in the electro-optical properties of the PDLC. For example, addition of Au NPs to PDLC microstructure lowers its threshold voltage by almost 50% and increases optical transmission in a manner that depends on NPs concentration and applied electric field.ootnotetextA. Hinojosa and S. C. Sharma, Applied Physics Letters, 97, 081114 (2010) In order to understand these observations, we have carried out electro-optical measurements on several PDLCs as functions of the polarization of the incident laser beam and applied electric field. In this presentation, we will discuss the results obtained from these experiments and suggest mechanism(s), which might explain NPs-induced changes in the electro-optical properties of PDLCs.

Hinojosa, Alfonso; Sharma, Suresh

2010-10-01

90

nanoparticles  

NASA Astrophysics Data System (ADS)

Thermal energy storage (TES) is extremely important in concentrated solar power (CSP) plants since it represents the main difference and advantage of CSP plants with respect to other renewable energy sources such as wind, photovoltaic, etc. CSP represents a low-carbon emission renewable source of energy, and TES allows CSP plants to have energy availability and dispatchability using available industrial technologies. Molten salts are used in CSP plants as a TES material because of their high operational temperature and stability of up to 500蚓. Their main drawbacks are their relative poor thermal properties and energy storage density. A simple cost-effective way to improve thermal properties of fluids is to dope them with nanoparticles, thus obtaining the so-called salt-based nanofluids. In this work, solar salt used in CSP plants (60% NaNO3 + 40% KNO3) was doped with silica nanoparticles at different solid mass concentrations (from 0.5% to 2%). Specific heat was measured by means of differential scanning calorimetry (DSC). A maximum increase of 25.03% was found at an optimal concentration of 1 wt.% of nanoparticles. The size distribution of nanoparticle clusters present in the salt at each concentration was evaluated by means of scanning electron microscopy (SEM) and image processing, as well as by means of dynamic light scattering (DLS). The cluster size and the specific surface available depended on the solid content, and a relationship between the specific heat increment and the available particle surface area was obtained. It was proved that the mechanism involved in the specific heat increment is based on a surface phenomenon. Stability of samples was tested for several thermal cycles and thermogravimetric analysis at high temperature was carried out, the samples being stable.

Andreu-Cabedo, Patricia; Mondragon, Rosa; Hernandez, Leonor; Martinez-Cuenca, Raul; Cabedo, Luis; Julia, J. Enrique

2014-10-01

91

Flavonoid (myricetin, quercetin, kaempferol, luteolin, and apigenin) content of edible tropical plants.  

PubMed

Studies were conducted on the flavonoids (myricetin, quercetin, kaempferol, luteolin, and apigenin) contents of 62 edible tropical plants. The highest total flavonoids content was in onion leaves (1497.5 mg/kg quercetin, 391.0 mg/kg luteolin, and 832.0 mg/kg kaempferol), followed by Semambu leaves (2041.0 mg/kg), bird chili (1663.0 mg/kg), black tea (1491.0 mg/kg), papaya shoots (1264.0 mg/kg), and guava (1128.5 mg/kg). The major flavonoid in these plant extracts is quercetin, followed by myricetin and kaempferol. Luteolin could be detected only in broccoli (74.5 mg/kg dry weight), green chili (33.0 mg/kg), bird chili (1035.0 mg/kg), onion leaves (391.0 mg/kg), belimbi fruit (202.0 mg/kg), belimbi leaves (464.5 mg/kg), French bean (11.0 mg/kg), carrot (37.5 mg/kg), white radish (9.0 mg/kg), local celery (80.5 mg/kg), limau purut leaves (30.5 mg/kg), and dried asam gelugur (107.5 mg/kg). Apigenin was found only in Chinese cabbage (187.0 mg/kg), bell pepper (272.0 mg/kg), garlic (217.0 mg/kg), belimbi fruit (458.0 mg/kg), French peas (176.0 mg/kg), snake gourd (42.4 mg/kg), guava (579.0 mg/kg), wolfberry leaves (547.0 mg/kg), local celery (338.5 mg/kg), daun turi (39.5 mg/kg), and kadok (34.5 mg/kg). In vegetables, quercetin glycosides predominate, but glycosides of kaempferol, luteolin, and apigenin are also present. Fruits contain almost exclusively quercetin glycosides, whereas kaempferol and myricetin glycosides are found only in trace quantities. PMID:11410016

Miean, K H; Mohamed, S

2001-06-01

92

Dietary Flavonoids as Therapeutics for Preterm Birth: Luteolin and Kaempferol Suppress Inflammation in Human Gestational Tissues In Vitro  

PubMed Central

Infection/inflammation is commonly associated with preterm birth (PTB), initiating uterine contractions and rupture of fetal membranes. Proinflammatory cytokines induce matrix metalloproteinases (MMPs) that degrade the extracellular matrix (ECM) and prostaglandins which initiate uterine contractions. Nuclear factor-?B (NF-?B) and activator-protein- (AP-)1 have key roles in the formation of these prolabour mediators. In nongestational tissues, dietary flavonoids such as luteolin and kaempferol inhibit NF-?B, AP-1, and their downstream targets. The aim of this study was to determine if luteolin and kaempferol reduce infection-induced prolabour mediators in human gestational tissues. Fetal membranes were incubated with LPS, and primary amnion cells and myometrial cells were incubated with IL-1? in the absence or presence of luteolin or kaempferol. Luteolin and kaempferol significantly reduced LPS-induced secretion of proinflammatory cytokines (IL-6 and IL-8) and prostaglandins (PGE2 and PGF2?) in fetal membranes, IL-1?-induced COX-2 gene expression and prostaglandin production in myometrium, and IL-1?-induced MMP-9 activity in amnion and myometrial cells. Luteolin and kaempferol decreased IL-1?-induced NF-?B p65 DNA binding activity and nuclear c-Jun expression. In conclusion, luteolin and kaempferol inhibit prolabour mediators in human gestational tissues. Given the central role of inflammation in provoking preterm labour, phytophenols may be a therapeutic approach to reduce the incidence of PTB. PMID:23840918

Wall, Courtney; Lim, Ratana; Poljak, Marin; Lappas, Martha

2013-01-01

93

Influence of Cd2+/S2- molar ratio and of different capping environments in the optical properties of CdS nanoparticles incorporated within a hybrid diureasil matrix  

NASA Astrophysics Data System (ADS)

The incorporation of CdS nanoparticles (NPs), as prepared through colloidal methods using reverse micelles, within diureasil hybrid organic-inorganic sol-gel matrices was investigated. Several experimental conditions, namely the influence of capping agent 3-mercaptopropyltrimethoxysilane (MPTMS) or the use of tetraethoxysilane (TEOS), were studied in order to assure the preservation of the original optical properties of colloidal CdS NPs after the incorporation of the NPs within the solid diureasil hybrid matrix. The diureasil matrix is based on a siliceous network cross linked through urea bonds to poly(oxyethylene)/poly(oxypropylene) (PEO/PPO) chains. The influence of the Cd2+/S2- molar ratio of the NPs in the stability and dispersion of the NPs within the diureasil matrix was also investigated. The obtained CdS doped hybrid matrix was characterized by absorption, steady-state and time-resolved photoluminescence (PL) spectroscopy and by transmission electron microscopy (TEM). The stability of the CdS NPs within the hybrid matrix showed to be dependent on the Cd2+/S2- molar ratio used in the synthesis of the NPs. The use of MPTMS proved to be crucial in the preservation of the original optical properties of the colloidal CdS NPs after the incorporation of the NPs within the hybrid matrix. The effect of MPTMS was in turn influenced by the Cd2+/S2- molar ratio employed in the synthesis of the CdS NPs. The use of MPTMS was less effective when Cd2+/S2- molar ratio equal to 0.5 was used. In the absence of MPTMS or TEOS larger NPs size distribution and clustering of the CdS NPs were obtained after the transfer of the NPs into the hybrid matrix.

Gon蓷lves, Luis F. F. F.; Silva, Carlos J. R.; Kanodarwala, Fehmida K.; Stride, John A.; Pereira, Mario R.; Gomes, Maria J. M.

2014-09-01

94

Incorporation of photosenzitizer hypericin into synthetic lipid-based nano-particles for drug delivery and large unilamellar vesicles with different content of cholesterol  

NASA Astrophysics Data System (ADS)

Low-density lipoproteins (LDL) and high-density lipoproteins (HDL) are attractive natural occurring vehicles for drug delivery and targeting to cancer tissues. The capacity of both types of the lipoproteins to bind hydrophobic drugs and their functionality as drug carriers have been examined in several studies and it has been also shown that mixing of anticancer drugs with LDL or HDL before administration led to an increase of cytotoxic effects of the drugs in the comparison when the drugs were administered alone. However, a difficult isolation of the lipoproteins in large quantity from a biological organism as well as a variability of the composition and size of these molecules makes practical application of LDL and HDL as drug delivery systems quite complicated. Synthetic LDL and HDL and large unilamellar vesicles (LUV) are potentially suitable candidates to substitute the native lipoproteins for targeted and effective drug delivery. In this work, we have studied process of an association of potent photosensitizer hypericin (Hyp) with synthetic lipid-based nano-particles (sLNP) and large unilamellar vesicles (LUV) containing various amount of cholesterol. Cholesterol is one of the main components of both LDL and HDL particles and its presence in biological membranes is known to be a determining factor for membrane properties. It was found that the behavior of Hyp incorporation into sLNP particles with diameter ca ~ 90 nm is qualitatively very similar to that of Hyp incorporation into LDL (diameter ca. 22 nm) and these particles are able to enter U-87 MG cells by endocytosis. The presence of cholesterol in LUV influences the capacity of these vesicles to incorporate Hyp into their structure.

Joniova, Jaroslava; Blascakova, Ludmila; Jancura, Daniel; Nadova, Zuzana; Sureau, Franck; Miskovsky, Pavol

2014-08-01

95

Determination of functionalized gold nanoparticles incorporated in hydrophilic and hydrophobic microenvironments by surface modification of quartz crystal microbalance  

NASA Astrophysics Data System (ADS)

In this study, plasma deposition methods were used to immobilize Au electrode of a quartz crystal microbalance (QCM) to create different microenvironments for mass measurement of various modified Au nanoparticles (AuNPs). AuNPs were modified by 11-mercaptoundecanoic acid (MUA) and 1-decanethiol (DCT) for potential applications to drug release, protective coatings, and immunosensors. We aimed to develop a highly sensitive and reliable method to quantify the mass of various modified AuNPs. The surface of AuNPs and Au electrode was coated with polymer films, as determined by Fourier transform infrared spectroscopy and atomic force microscopy. Measurements obtained for various AuNPs and the plasma-treated surface of the Au electrode were compared with those obtained for an untreated Au electrode. According to the resonant frequency shift of QCM, a linear relationship was observed that significantly differed for AuNPs, MUA-AuNPs, and DCT-AuNPs (R2 range, 0.94-0.965, 0.934-0.972, and 0.874-0.9514, respectively). Compared to inductively coupled plasma and micro-computerized tomography, the QCM method with plasma treatment has advantages of real-time monitoring, greater sensitivity, and lower cost. Our results demonstrate that surface modifications measured by a QCM system for various modified AuNPs were reliable.

Wu, Tsui-Hsun; Liao, Shu-Chuan; Chen, Ying-Fang; Huang, Yi-You; Wei, Yi-Syuan; Tu, Shu-Ju; Chen, Ko-Shao

2013-06-01

96

Vascular effects of a soy leaves (Glycine max) extract and kaempferol glycosides in isolated rat carotid arteries.  

PubMed

We have recently purified genistin, and six kaempferol glycosides from a soy leaves ( Glycine max L. Merr.) butanol extract. Here we report the vascular effects of the extract and purified genistin and kaempferol glycosides on contractions induced by different constricting agonists in isolated rat carotid arteries. The butanol extract relaxed artery rings preconstricted by 9,11-dideoxy-11alpha,9alpha-epoxy-methanoprostaglandin F 2 alpha (U46619) or [5 Z,9alpha,11alpha,13 E,15 S]-9,11,15-trihydroxyprosta-5,13-dienoic acid (PGF 2 alpha ) in a dose-dependent manner and this effect was independent of the presence of endothelium. The extract also inhibited the concentration-dependent contraction to U46619 with a slight reduction of the maximal response. The extract produced partial relaxation of both phenylephrine-preconstricted endothelium-intact and -denuded rings. In contrast, the extract had no effect on the contractile response to 50 mM extracellular K (+). None of the six kaempferol glycosides affected vessel tension induced by U46619. A mixture of kaempferol glycosides prepared according to their relative composition in the extract had no effect either. However, kaempferol relaxed U46619- and high K (+)-contracted rings to the same extent. Endothelium played no role in kaempferol-induced relaxation. Genistein induced concentration-dependent relaxation and this effect was attenuated in the endothelium-denuded rings. Genistin caused a smaller relaxant effect. The present results indicate that a butanol extract from soy leaves causes endothelium-independent relaxation in rat carotid artery rings. Kaempferol glycosides, accounting for approximately 48 % of the extract in weight, are not the ingredients responsible for the extract-induced relaxation. Genistein and genistin also caused relaxation, however, the dose range is beyond that of the extract causing relaxation. PMID:12094288

Ho, Hing Man; Chen, Ruoyun; Huang, Yu; Chen, Zhen Yu

2002-06-01

97

The anti-inflammatory effect of kaempferol on early atherosclerosis in high cholesterol fed rabbits  

PubMed Central

Background Atherosclerosis has been widely accepted as an inflammatory disease of vascular, adhesion molecules play an important role in the early progression of it. The aim of the present study was to evaluate the effect of kaempferol on the inflammatory molecules such as E-selectin (E-sel), intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesionmolecule-1 (VCAM-1) and monocyte chemotactic protein-1 (MCP-1) in high cholesterol induced atherosclerosis rabbit models. Methods Thirty male New Zealand white (NZW) rabbits were randomly divided into five groups, control group, model group, fenofibrate (12mg/kg) group and kaempferol groups (150 mg/kg and 30 mg/kg). The rabbits were fed with a normal diet or a high cholesterol diet for 10 weeks. Levels of blood lipids, serum tumour-necrosis factor-alpha (TNF-?) and serum interleukin-1beta (IL-1?) were detected at the end of the sixth and tenth week. Malonaldehyde (MDA) level and superoxide dismutase (SOD) activity in serum were also determined. Lesion areas of the aorta were measured with morphometry analysis after ten weeks. Gene expression of E-sel, ICAM-1, VCAM-1 and MCP-1 in aortas was determined by RT-PCR (reverse transcription-polymerase chain reaction). Immunohistochemical staining was employed to measure protein expression of E-sel, ICAM-1, VCAM-1 and MCP-1. Results Model rabbits fed with ten weeks of high-cholesterol diet developed significant progression of atherosclerosis. Compared with the control, levels of blood lipids, TNF-?, IL-1? and MDA increased markedly in serum of model rabbits, while SOD levels decreased. Gene and protein expressions of E-sel, ICAM-1, VCAM-1 and MCP-1 in atherosclerotic aortas increased remarkably in model group. However, comparing to the model rabbits, levels of TNF-?, IL-1? and MDA decreased significantly and serum SOD activity increased, gene and protein expressions of E-sel, ICAM-1, VCAM-1 and MCP-1 in aortas decreased significantly with the treatment of kaempferol. Conclusion Kaempferol shows anti-atherosclerotic effect by modulating the gene and protein expression of inflammatory molecules. PMID:23895132

2013-01-01

98

In vitro activity of kaempferol isolated from the Impatiens balsamina alone and in combination with erythromycin or clindamycin against Propionibacterium acnes.  

PubMed

The in vitro antibacterial activity against antibiotic-resistant Propionibacterium acnes of kaempferol isolated from the Impatiens balsamina alone and in combination with erythromycin or clindamycin antibiotics was investigated. The antibiotic combination effect against antibiotic-resistant P. acnes was studied by checkerboard test. Kaempferol and quercetin demonstrated antibacterial activities against P. acnes. Minimum inhibitory concentrations (MICs) for both compounds were < or =32 ug/ml and < or =64 ug/ml for clindamycin-sensitive and-resistant P. acnes, respectively. The four combination formulations (kaempferol and either erythromycin or clindamycin; quercetin and either erythromycin or clindamycin) exhibited a synergic inhibition of P. acnes growth. The combination of kaempferol with quercetin showed an indifferent effect. The combination of clindamycin with kaempferol or quercetin showed a greater synergic effect than that of erythromycin with kaempferol or quercetin. Thus, these combinations demonstrated the potential to treat acne. PMID:17978809

Lim, Young-Hee; Kim, In-Hwan; Seo, Jung-Ju

2007-10-01

99

Determination of free and glucuronidated kaempferol in rat plasma by LC-MS/MS: application to pharmacokinetic study.  

PubMed

Flavanoid kaempferol is mainly present as glucuronides and sulfates in rat plasma, and small amounts of the intact aglycone are also detected. In the this study, a rapid, specific and sensitive liquid chromatography-electrospray ionization-tandem mass spectrometry method (HPLC-MS/MS) was developed and validated for determination of kaempferol and its major metabolite glucuronidated kaempferol in rat plasma. A liquid-liquid extraction with acetic ether was involved for the extraction of kaempferol and internal standard. Analytes were separated on a C18 column (150 mm x 2.1 mm, 4.5 microm, Waters Corp.) with isocratic elution at a flow-rate of 0.3 ml min(-1). The mobile phase was consisted of 0.5% formic acid and acetonitrile (50:50, v/v). The Quattro Premier HPLC-MS/MS was operated under the multiple reaction-monitoring mode (MRM) using the electrospray ionization technique. The method was validated according to the FDA guidelines for validation of bioanalytical method. The validated method was successfully applied to the study of the pharmacokinetics in rats after oral administration of kaempferol with different doses. PMID:20591752

Zhang, Wei-Dong; Wang, Xiao-Juan; Zhou, Si-Yuan; Gu, Yi; Wang, Rong; Zhang, Tao-Li; Gan, Hong-Quan

2010-08-01

100

The berry constituents quercetin, kaempferol, and pterostilbene synergistically attenuate reactive oxygen species: Involvement of the Nrf2-ARE signaling pathway.  

PubMed

Quercetin, kaempferol, and pterostilbene are abundant in berries. The anti-oxidative properties of these constituents may contribute to cancer chemoprevention. However, their precise mechanisms of action and their combinatorial effects are not completely understood. Nuclear factor (erythroid-derived 2)-like 2 (Nrf2) regulates anti-oxidative stress enzymes and Phase II drug metabolizing/detoxifying enzymes by binding to antioxidant response element (ARE). This study aimed to investigate the anti-oxidative stress activities of quercetin, kaempferol, and pterostilbene individually and in combination, as well as the involvement of the Nrf2-ARE signaling pathway. Quercetin, kaempferol, and pterostilbene all exhibited strong free-radical scavenging activity in the DPPH assay. The MTS assay revealed that low concentration combinations we tested were relatively non-toxic to HepG2-C8 cells. The results of the DCFH-DA assay and combination index (CI) indicated that quercetin, kaempferol, and pterostilbene attenuated intracellular reactive oxygen species (ROS) levels when pretreated individually and had synergistic effects when used in combination. In addition, the combination treatment significantly induced ARE and increased the mRNA and protein expression of Nrf2-regulated genes. Collectively, our study demonstrated that the berry constituents quercetin, kaempferol, and pterostilbene activated the Nrf2-ARE signaling pathway and exhibited synergistic anti-oxidative stress activity at appropriate concentrations. PMID:25111660

Saw, Constance Lay Lay; Guo, Yue; Yang, Anne Yuqing; Paredes-Gonzalez, Ximena; Ramirez, Christina; Pung, Douglas; Kong, Ah-Ng Tony

2014-10-01

101

nanoparticles  

NASA Astrophysics Data System (ADS)

In this work, we present the role of vanadium ions (V+5 and V+3), oxygen vacancies (VO), and interstitial zinc (Zni) to the contribution of specific magnetization for a mixture of ZnO-V2O5 nanoparticles (NPs). Samples were obtained by mechanical milling of dry powders and ethanol-assisted milling for 1 h with a fixed atomic ratio V/Zn?=?5% at. For comparison, pure ZnO samples were also prepared. All samples exhibit a room temperature magnetization ranging from 1.18??10-3 to 3.5??10-3 emu/gr. Pure ZnO powders (1.34??10-3 emu/gr) milled with ethanol exhibit slight increase in magnetization attributed to formation of Zni, while dry milled ZnO powders exhibit a decrease of magnetization due to a reduction of VO concentration. For the ZnO-V2O5 system, dry milled and thermally treated samples under reducing atmosphere exhibit a large paramagnetic component associated to the formation of V2O3 and secondary phases containing V+3 ions; at the same time, an increase of VO is observed with an abrupt fall of magnetization to ??~?0.7??10-3 emu/gr due to segregation of V oxides and formation of secondary phases. As mechanical milling is an aggressive synthesis method, high disorder is induced at the surface of the ZnO NPs, including VO and Zni depending on the chemical environment. Thermal treatment restores partially structural order at the surface of the NPs, thus reducing the amount of Zni at the same time that V2O5 NPs segregate reducing the direct contact with the surface of ZnO NPs. Additional samples were milled for longer time up to 24 h to study the effect of milling on the magnetization; 1-h milled samples have the highest magnetizations. Structural characterization was carried out using X-ray diffraction and transmission electron microscopy. Identification of VO and Zni was carried out with Raman spectra, and energy-dispersive X-ray spectroscopy was used to verify that V did not diffuse into ZnO NPs as well to quantify O/Zn ratios.

Olive-M幯dez, Sion F.; Santill嫕-Rodr璲uez, Carlos R.; Gonz嫮ez-Valenzuela, Ricardo A.; Espinosa-Maga鎙, Francisco; Matutes-Aquino, Jos A.

2014-04-01

102

Study of Kaempferol Glycoside as an Insulin Mimic Reveals Glycon To Be the Key Active Structure  

PubMed Central

Diabetes mellitus is increasing in prevalence with patient numbers rising throughout the world. Current treatments for diabetes mellitus focus on control of blood glucose levels. Certain kinds of flavonoids or their glycosides stimulate cells to improve glucose uptake and lower blood glucose levels. We synthesized kaempferol 3-O-neohesperidoside (1), a naturally occurring substance present in Cyathea phalerata Mart., reported to mimic the action of insulin. Synthetic 1 promoted glucose uptake in the cultured cell line, L6. Further studies to determine the core structure responsible for this activity using synthetic compounds revealed neohesperidose to be the primary pharmacophore. These findings support the use of certain saccharides as a potential novel treatment for diabetes mellitus by replacing or supporting insulin. PMID:24900249

2010-01-01

103

Quantum dots (QDs) based fluorescence probe for the sensitive determination of kaempferol.  

PubMed

In this work, using the quenching of fluorescence of thioglycollic acid (TGA)-capped CdTe quantum dots (QDs), a novel method for the determination of kaempferol (KAE) has been developed. Under optimum conditions, a linear calibration plot of the quenched fluorescence intensity at 552nm against the concentration of KAE was observed in the range of 4-44?gmL(-1) with a detection limit (3?/K) of 0.79?gmL(-1). In addition, the detailed reaction mechanism has also been proposed on the basis of electron transfer supported by ultraviolet-visible (UV-vis) absorption and fluorescence (FL) spectroscopy. The method has been applied for the determination of KAE in pharmaceutical preparations with satisfactory results. The proposed method manifested several advantages such as high sensitivity, short analysis time, low cost and ease of operation. PMID:24929317

Tan, Xuanping; Liu, Shaopu; Shen, Yizhong; He, Youqiu; Yang, Jidong

2014-12-10

104

Effects of Long-Term Feeding of the Polyphenols Resveratrol and Kaempferol in Obese Mice  

PubMed Central

The effect of the intake of antioxidant polyphenols such as resveratrol and others on survival and different parameters of life quality has been a matter of debate in the last years. We have studied here the effects of the polyphenols resveratrol and kaempferol added to the diet in a murine model undergoing long-term hypercaloric diet. Using 50 mice for each condition, we have monitored weight, survival, biochemical parameters such as blood glucose, insulin, cholesterol, triglycerides and aspartate aminotransferase, neuromuscular coordination measured with the rotarod test and morphological aspect of stained sections of liver and heart histological samples. Our data show that mice fed since they are 3-months-old with hypercaloric diet supplemented with any of these polyphenols reduced their weight by about 57% with respect to the controls fed only with hypercaloric diet. We also observed that mice fed with any of the polyphenols had reduced levels of glucose, insulin and cholesterol, and better marks in the rotarod test, but only after 1 year of treatment, that is, during senescence. No effect was observed in the rest of the parameters studied. Furthermore, although treatment with hypercaloric diets induced large changes in the pattern of gene expression in liver, we found no significant changes in gene expression induced by the presence of any of the polyphenols. Thus, our data indicate that addition of resveratrol or kaempferol to mice food produces an initial decrease in weight in mice subjected to hypercaloric diet, but beneficial effects in other parameters such as blood glucose, insulin and cholesterol, and neuromuscular coordination, only appear after prolonged treatments. PMID:25386805

Montero, Mayte; de la Fuente, Sergio; Fonteriz, Rosalba I.; Moreno, Alfredo; Alvarez, Javier

2014-01-01

105

Kaempferol inhibits IL-1?-stimulated, RANKL-mediated osteoclastogenesis via downregulation of MAPKs, c-Fos, and NFATc1.  

PubMed

Kaempferol is one of the most common flavonoid that is present in a variety of vegetables and fruits and has effects on bone metabolism. The present study was performed to define the effects of kaempferol on interleukin (IL)-1?-stimulated receptor activator of NF-?B ligand (RANKL)-mediated osteoclast differentiation. Bone marrow cells were harvested from 6-week-old male imprinting control region mice, and the differentiation of osteoclasts from these cells was evaluated by tartrate-resistant acid phosphatase staining and resorption pit formation assay. Phosphorylated extracellular signal-regulated kinase (p-ERK), phosphorylated p38, phosphorylated c-Jun amino-terminal kinase, NF-?B (p65), I?B?, c-Fos, and nuclear factor of activated T cells c1 (NFATc1) expressions were examined by Western blotting and quantitative RT-PCR. Kaempferol inhibits IL-1?-stimulated, RANKL-mediated osteoclast differentiation and also inhibits IL-1?-stimulated, RANKL-mediated phosphorylation of ERK 1/2, p38 and JNK MAP kinases, and expressions of c-Fos and NFATc1. These results indicate that kaempferol has an inhibitory role in the bone loss by preventing osteoclast formation and suggest that it might be a novel therapeutic agent for the treatment of inflammatory arthritis by managing bone destruction. PMID:24696323

Lee, Won-Seok; Lee, Eun-Gyeong; Sung, Myung-Soon; Yoo, Wan-Hee

2014-08-01

106

Simultaneous determination by HPLC of quercetin and kaempferol in three Sedum medicinal plants harvested in different seasons.  

PubMed

A high-performance liquid chromatography method was established for the fast quantification of quercetin and kaempferol in three Sedum crude medicines: Sedi Herba (Sedum sarmentosum Bunge.), Sedi Linearis Herba (Sedum lineare Thunb.) and Sedi Emarginati Herba (Sedum emarginatum Migo.). The column used was a YMC-pack ODS-A (250 4.6 mm, 5 痠), the mobile phase was a solution of methanol-0.4% phosphoric acid (47:53) with a flow rate of 1.0 mL/min at 35蚓 and the detection wavelength was 360 nm. The calibration curves for quercetin and kaempferol were linear over the range of 0.01-0.62 痢 for quercetin and 0.02-0.78 痢 for kaempferol, and the average recoveries were 99.72% [relative standard deviation (RSD): 1.63% and 99.50% (RSD: 1.16%), respectively]. In conclusion, the method established in this paper is accurate and repeatable. It can be used for the determination of quercetin and kaempferol, controlling the quality of the three crude drugs. Furthermore, the experimental data showed that the best harvest season for the three Sedum medicinal species should be the full-bloom period between the end of April and the beginning of May. PMID:23572321

Wang, Luyao; Mei, Qing; Wan, Dingrong

2014-04-01

107

Kaempferol Reduces Matrix Metalloproteinase-2 Expression by Down-Regulating ERK1/2 and the Activator Protein-1 Signaling Pathways in Oral Cancer Cells  

PubMed Central

Background Kaempferol has been proposed as a potential drug for cancer chemoprevention and treatment because it is a natural polyphenol contained in plant-based foods. Recent studies have demonstrated that kaempferol protects against cardiovascular disease and cancer. Based on this finding, we investigated the mechanisms by which kaempferol produces the anti-metastatic effect in human tongue squamous cell carcinoma SCC4 cells. Methodology/Principal Findings In this study, we provided molecular evidence associated with the anti-metastatic effect of kaempferol by demonstrating a substantial suppression of SCC4 cell migration and invasion. This effect was associated with reduced expressions of MMP-2 and TIMP-2 mRNA and protein levels. Analysis of the transcriptional regulation indicated that kaempferol inhibited MMP-2 transcription by suppressing c-Jun activity. Kaempferol also produced an inhibitory effect on the phosphorylation of ERK1/2. Conclusions These findings provide new insights into the molecular mechanisms involved in the anti-metastatic effect of kaempferol, and are valuable in the prevention of oral cancer metastasis. PMID:24278338

Lin, Chiao-Wen; Chen, Pei-Ni; Chen, Mu-Kuan; Yang, Wei-En; Tang, Chih-Hsin; Yang, Shun-Fa; Hsieh, Yih-Shou

2013-01-01

108

Anti-cancer Effect and Underlying Mechanism(s) of Kaempferol, a Phytoestrogen, on the Regulation of Apoptosis in Diverse Cancer Cell Models  

PubMed Central

Phytoestrogens exist in edible compounds commonly found in fruits or plants. For long times, phytoestrogens have been used for therapeutic treatments against human diseases, and they can be promising ingredients for future pharmacological industries. Kaempferol is a yellow compound found in grapes, broccoli and yellow fruits, which is one of flavonoid as phytoestrogens. Kaempferol has been suggested to have an antioxidant and anti-inflammatory effect. In past decades, many studies have been performed to examine anti-toxicological role(s) of kaempferol against human cancers. It has been shown that kaempferol may be involved in the regulations of cell cycle, metastasis, angiogenesis and apoptosis in various cancer cell types. Among them, there have been a few of the studies to examine a relationship between kaempferol and apoptosis. Thus, in this review, we highlight the effect(s) of kaempferol on the regulation of apoptosis in diverse cancer cell models. This could be a forecast in regard to use of kaempferol as promising treatment against human diseases. PMID:24578792

Kim, Seung-Hee

2013-01-01

109

Thermally responsive core-shell nanoparticles self-assembled from cholesteryl end-capped and grafted polyacrylamides:; drug incorporation and in vitro release.  

PubMed

The thermally responsive cholesteryl end-capped poly(N-isopropylacrylamide-co-N,N-dimethylacrylamide) and cholesteryl grafted poly[N-isopropylacrylamide-co-N-(hydroxymethyl) acrylamide] amphiphilic polymers were synthesized and utilized to encapsulate cyclosporin A (CyA) and indomethacin (IND) within core-shell nanoparticles by a membrane dialysis method. The blank and drug-loaded nanoparticles were characterized using various analytical tools. The blank nanoparticles had a mean diameter less than 100 nm, whereas the drug-loaded nanoparticles were between 100 and 200 nm in diameter. The CAC value of cholesteryl end-capped and grafted polymers in PBS (pH 7.4) was estimated to be 16 and 8.5mg/l, respectively. The LCST value for both nanoparticle systems in PBS (pH 7.4) was determined to be 33.4 degrees C and 38.3 degrees C, respectively. The presence of proteins in PBS reduced the LCST. The core-shell nanoparticles provided great capacity for drug loading. In particular, the cholesteryl grafted polymer yielded a higher encapsulation efficiency for drugs. Compared to CyA, better entrapment was observed for IDN. A reduced fabrication temperature provided greater drug encapsulation efficiency. An increase in the initial drug content yielded lower drug encapsulation efficiencies at 10 degrees C and 15 degrees C. Increasing the polymer concentration increased drug encapsulation efficiency. The drug-loading process was analyzed to understand the effect of various fabrication parameters on drug encapsulation efficiency. IND release from the nanoparticles was responsive to temperature changes, being faster at a temperature around the LCST than below the LCST. PMID:15046920

Chaw, Cheng-Shu; Chooi, Kar-Wai; Liu, Xue-Ming; Tan, Cherng-Wen; Wang, Lin; Yang, Yi-Yan

2004-08-01

110

Self-assembly of a model peptide incorporating a hexa-histidine sequence attached to an oligo-alanine sequence, and binding to gold NTA/nickel nanoparticles.  

PubMed

Amyloid fibrils are formed by a model surfactant-like peptide (Ala)10-(His)6 containing a hexa-histidine tag. This peptide undergoes a remarkable two-step self-assembly process with two distinct critical aggregation concentrations (cac's), probed by fluorescence techniques. A micromolar range cac is ascribed to the formation of prefibrillar structures, whereas a millimolar range cac is associated with the formation of well-defined but more compact fibrils. We examine the labeling of these model tagged amyloid fibrils using Ni-NTA functionalized gold nanoparticles (Nanogold). Successful labeling is demonstrated via electron microscopy imaging. The specificity of tagging does not disrupt the ?-sheet structure of the peptide fibrils. Binding of fibrils and Nanogold is found to influence the circular dichroism associated with the gold nanoparticle plasmon absorption band. These results highlight a new approach to the fabrication of functionalized amyloid fibrils and the creation of peptide/nanoparticle hybrid materials. PMID:25105839

Hamley, Ian W; Kirkham, Steven; Dehsorkhi, Ashkan; Castelletto, Valeria; Adamcik, Jozef; Mezzenga, Raffaele; Ruokolainen, Janne; Mazzuca, Claudia; Gatto, Emanuela; Venanzi, Mariano; Placidi, Ernesto; Bilalis, Panayiotis; Iatrou, Hermis

2014-09-01

111

A fragmentation study of kaempferol using electrospray quadrupole time-of-flight mass spectrometry at high mass resolution  

Microsoft Academic Search

A mass spectrometric method based on the combined use of electrospray ionization, collision-induced dissociation and tandem mass spectrometry at high mass resolution has been applied to an investigation of the structural characterization of protonated and deprotonated kaempferol (3,5,7,4?-tetrahydroxyflavone). Low-energy product ion mass spectra of [M+H]+ ions showed simple fragmentations of the C ring that permitted characterization of the substituents in

Raymond E. March; Xiu-Sheng Miao

2004-01-01

112

Anti- Japanese-Encephalitis-Viral Effects of Kaempferol and Daidzin and Their RNA-Binding Characteristics  

PubMed Central

Background New therapeutic tools and molecular targets are needed for treatment of Japanese encephalitis virus (JEV) infections. JEV requires an ?-1 translational frameshift to synthesize the NS1' protein required for viral neuroinvasiveness. Several flavonoids have been shown to possess antiviral activity in vitro against a wide spectrum of viruses. To date, the antiviral activities of flavonol kaempferol (Kae) and isoflavonoid daidzin (Dai) against JEV have not been described. Methodology/Principal Findings The 50% cytotoxic concentration (CC50) and 50% effective concentration (EC50) against JEV were investigated in BHK21 cells by MTS reduction. Activity against viral genomic RNA and proteins was measured by real-time RT-PCR and western blotting. The frameshift site RNA-binding characterization was also determined by electrospray ionization mass spectrometry, isothermal titration calorimetry and autodocking analysis. EC50 values of Kae and Dai were 12.6 and 25.9 然 against JEV in cells pretreated before infection, whereas in cells infected before treatment, EC50 was 21.5 and 40.4 然, respectively. Kae exhibited more potent activity against JEV and RNA binding in cells following internalization through direct inhibition of viral replication and protein expression, indicating that its antiviral activity was principally due to direct virucidal effects. The JEV frameshift site RNA (fsRNA) was selected as a target for assaying Kae and Dai. ITC of fsRNA revealed an apparent Kb value for Kae that was nine fold stronger than that for Dai. This binding was confirmed and localized to the RNA using ESI-MS and autodock analysis. Kae could form non-covalent complexes with fsRNA more easily than Dai could. Conclusions/Significance Kae demonstrates more potent antiviral activity against JEV than does Dai. The mode of action of Kae as an anti-JEV agent seems to be related to its ability to inactivate virus by binding with JEV fsRNA. PMID:22276167

Hu, Yongfeng; Liu, Liguo; Yang, Fan; Jin, Qi

2012-01-01

113

Inhibition of airway epithelial-to-mesenchymal transition and fibrosis by kaempferol in endotoxin-induced epithelial cells and ovalbumin-sensitized mice.  

PubMed

Chronic airway remodeling is characterized by structural changes within the airway wall, including smooth muscle hypertrophy, submucosal fibrosis and epithelial shedding. Epithelial-to-mesenchymal transition (EMT) is a fundamental mechanism of organ fibrosis, which can be induced by TGF-?. In the in vitro study, we investigated whether 1-20??M kaempferol inhibited lipopolysaccharide (LPS)-induced bronchial EMT in BEAS-2B cells. The in vivo study explored demoting effects of 10-20?mg/kg kaempferol on airway fibrosis in BALB/c mice sensitized with ovalbumin (OVA). LPS induced airway epithelial TGF-?1 signaling that promoted EMT with concurrent loss of E-cadherin and induction of ?-smooth muscle actin (?-SMA). Nontoxic kaempferol significantly inhibited TGF-?-induced EMT process through reversing E-cadherin expression and retarding the induction of N-cadherin and ?-SMA. Consistently, OVA inhalation resulted in a striking loss of epithelial morphology by displaying myofibroblast appearance, which led to bronchial fibrosis with submucosal accumulation of collagen fibers. Oral administration of kaempferol suppressed collagen deposition, epithelial excrescency and goblet hyperplasia observed in the lung of OVA-challenged mice. The specific inhibition of TGF-? entailed epithelial protease-activated receptor-1 (PAR-1) as with 20??M kaempferol. The epithelial PAR-1 inhibition by SCH-79797 restored E-cadherin induction and deterred ?-SMA induction, indicating that epithelial PAR-1 localization was responsible for resulting in airway EMT. These results demonstrate that dietary kaempferol alleviated fibrotic airway remodeling via bronchial EMT by modulating PAR1 activation. Therefore, kaempferol may be a potential therapeutic agent targeting asthmatic airway constriction. PMID:24378645

Gong, Ju-Hyun; Cho, In-Hee; Shin, Daekeun; Han, Seon-Young; Park, Sin-Hye; Kang, Young-Hee

2014-03-01

114

Effect of pH on the complexation of kaempferol-4'-glucoside with three ?-cyclodextrin derivatives: isothermal titration calorimetry and spectroscopy study.  

PubMed

The utilization of kaempferol and its glycosides in food and pharmaceutical industries could be improved by the formation of inclusion complexes with cyclodextrins at different pH. This study explores the complexation of kaempferol-4'-glucoside with sulfobutyl ether-?-cyclodextrin (SBE-?-CD), hydroxypropyl-?-cyclodextrin (HP-?-CD), and methylated-?-cyclodextrin (M-?-CD) in phosphate buffer solutions of different pH using isothermal titration calorimetry, UV-vis absorption and proton nuclear magnetic resonance spectroscopy at 298.2 K. Experimental results showed that kaempferol-4'-glucoside binds with the three ?- cyclodextrins in the same 1:1 stoichiometry. The rank order of stability constants is SBE-?-CD > HP-?-CD > M-?-CD at the same pH level and pH 6.0 > pH 7.4 > pH 9.0 for the same cyclodextrin. The binding of kaempferol-4'-glucoside with the three ?-cyclodextrin derivatives is synergistically driven by enthalpy and entropy at pH 6.0 and enthalpy-driven at pH 7.4 and 9.0. The possible inclusion mode was that in the cavity of ?-CD is included the planar benzopyranic-4-one part of the kaempferol-4'-glucoside. PMID:24308546

Zheng, Yan; Dong, Li-Na; Liu, Min; Chen, Aiju; Feng, Shangcai; Wang, Bingquan; Sun, Dezhi

2014-01-01

115

In vitro release and in vitro-in vivo correlation for silybin meglumine incorporated into hollow-type mesoporous silica nanoparticles  

PubMed Central

Background The purpose of this study was to develop a sustained drug-release model for water-soluble drugs using silica nanoparticles. Methods Hollow-type mesoporous silica nanoparticles (HMSNs) were prepared using Na2CO3 solution as the dissolution medium for the first time. The water-soluble compound, silybin meglumine, was used as the model drug. The WagnerNelson method was used to calculate the in vivo absorption fraction. Results The results of transmission electron microscopy and nitrogen adsorption revealed that the empty HMSNs had uniformly distributed particles of size 50100 nm, a spherical appearance, a large specific surface area (385.89 1.12 m2/g), and ultralow mean pore size (2.74 nm). The highly porous structure allowed a large drug-loading rate (58.91% 0.39%). In 0.08 M Na2CO3 solution, silybin meglumine-loaded HMSNs could achieve highly efficacious and long-term sustained release for 72 hours in vitro. The results of in vitroin vivo correlation revealed that HMSNs in 0.08 M Na2CO3 solution had a correlation coefficient R2 value of 0.9931, while those of artificial gastric juice and artificial intestinal juice were only 0.9287 and 0.7689, respectively. Conclusion The findings of in vitroin vivo correlation indicate that HMSNs together with Na2CO3 solution could achieve an excellent linear relationship between in vitro dissolution and in vivo absorption for 72 hours, leading to a promising model for sustained release of water-soluble drugs. PMID:22393284

Cao, Xia; Deng, Wen-Wen; Fu, Min; Wang, Liang; Tong, Shan-Shan; Wei, Ya-Wei; Xu, Ying; Su, Wei-Yan; Xu, Xi-ming; Yu, Jiang-Nan

2012-01-01

116

trans-[Ru(NO)Cl(cyclam)](PF6)2 and [Ru(NO)(Hedta)] incorporated in PLGA nanoparticles for the delivery of nitric oxide to B16-F10 cells: cytotoxicity and phototoxicity.  

PubMed

The immobilization and characterization of trans-[Ru(NO)Cl(cyclam)](PF6)2 (cyclam=1,4,8,11-tetraazacyclotetradecane), and [Ru(NO)(Hedta)] (Hedta=ethylenediaminetetraacetic acid) entrapped in poly(d,l-lactic-co-glycolic) acid (PLGA) nanoparticles (NP) using the double emulsification process is described. Scanning electron microscopy and dynamic light scattering revealed that the particles are spherical in shape, have a size distribution between 220 and 840 nm of diameter, and have a tendency to aggregate confirmed by a zeta potential between -3.2 and +3.5 mV. Using this method the loading efficiency was 26% for trans-[Ru(NO)Cl(cyclam)](PF6)2 and 32% for [Ru(NO)(Hedta)]. The release of the complexes from the NPs shows that cyclam-NP and Hedta-NP exhibited a two-phase exponential association release pattern, which was characterized by an initial complex burst during the first 24 h, followed by a slower release phase complex profile, due to a few pores observed in surface of nanoparticles using atomic force microscopy. The in vitro cytotoxic activity of the nitrosyl complexes in solution and incorporated in PLGA nanoparticles on melanoma cancer cells (cell line B16-F10) was investigated. The lower cytotoxicity of trans-[RuCl(cyclam)(NO)]2+ (12.42.6%) and [Ru(NO)(Hedta)] (4.02.7%) in solution compared to that of trans-[Ru(NO)(NH3)4py]3+ (46.16.4%) is consistent with the rate constant release of NO of these complexes (k-NO=6.210(-4) s(-1), 2.010(-3) s(-1), and 6.010(-2) s(-1), respectively); the cytotoxicities are also inhibited in the presence of the NO scavenger carboxy-PTIO. The phototoxicity of these complexes is due to NO release, which lead to 53.86.2% of cell death in the presence of trans-[Ru(NO)Cl(cyclam)](PF6)2 and 22.35.1% in the presence of [Ru(NO)(Hedta)]. The PLGA nanoparticles loaded with trans-[Ru(NO)Cl(cyclam)](PF6)2 and [Ru(NO)(Hedta)] exerted in vitro a reduced activity against melanoma cells when compared to the activity of complex in solution (nonentrapped in nanoparticles). Blank PLGA nanoparticles did not exhibit cytotoxicity. In the presence of light and of ruthenium nitrosyl complexes or cyclam-NP and Hedta-NP, B16-F10 cells displayed a considerable damage of the surface with rupture of the plasma membrane. This behavior is an indicative of the efficiency of the DDS to deliver the NO from the entrapped complex when photoinduced. PMID:23865934

Gomes, Anderson J; Espreafico, Enilza M; Tfouni, Elia

2013-10-01

117

Kaempferol-3-O-rhamnoside isolated from the leaves of Schima wallichii Korth. inhibits MCF-7 breast cancer cell proliferation through activation of the caspase cascade pathway  

PubMed Central

Plants consumed by non-human primates represent potential drug sources for human disease management. In this study, we isolated kaempferol-3-O-rhamnoside as an active compound from the leaves of Schima wallichii Korth., a plant commonly consumed by non-human primates. Its anti-cancer activities, including its ability to induce apoptotic mechanisms, were investigated in MCF-7 breast cancer cells. Results showed that in MCF-7 cells, kaempferol-3-O-rhamnoside inhibits cell proliferation in a dose-dependent manner and promotes apoptosis via the activation of the caspase signaling cascade, which includes caspase-9, caspase-3 and PARP. Our results provide a basis for further exploration of kaempferol-3-O-rhamnoside as an active compound for potential anti-cancer therapeutics. PMID:22783393

DIANTINI, AJENG; SUBARNAS, ANAS; LESTARI, KERI; HALIMAH, ELI; SUSILAWATI, YASMIWAR; SUPRIYATNA; JULAEHA, EUIS; ACHMAD, TRI H.; SURADJI, EKA W.; YAMAZAKI, CHIHO; KOBAYASHI, KENJI; KOYAMA, HIROSHI; ABDULAH, RIZKY

2012-01-01

118

Kaempferol in red and pinto bean seed (Phaseolus vulgaris L.) coats inhibits iron bioavailability using an in vitro digestion/human Caco-2 cell model.  

PubMed

Four different colored beans (white, red, pinto, and black beans) were investigated for factors affecting iron bioavailability using an in vitro digestion/human Caco-2 cell model. Iron bioavailability from whole beans, dehulled beans, and their hulls was determined. The results show that white beans contained higher levels of bioavailable iron compared to red, pinto, and black beans. These differences in bioavailable iron were not due to bean-iron and bean-phytate concentrations. Flavonoids in the colored bean hulls were found to be contributing to the low bioavailability of iron in the non-white colored beans. White bean hulls contained no detectable flavonoids but did contain an unknown factor that may promote iron bioavailability. The flavonoids, kaempferol and astragalin (kaempferol-3-O-glucoside), were identified in red and pinto bean hulls via HPLC and MS. Some unidentified anthocyanins were also detected in the black bean hulls but not in the other colored bean hulls. Kaempferol, but not astragalin, was shown to inhibit iron bioavailability. Treating in vitro bean digests with 40, 100, 200, 300, 400, 500, and 1000 microM kaempferol significantly inhibited iron bioavailability (e.g., 15.5% at 40 microM and 62.8% at 1000 microM) in a concentration-dependent fashion. Thus, seed coat kaempferol was identified as a potent inhibitory factor affecting iron bioavailability in the red and pinto beans studied. Results comparing the inhibitory effects of kaempferol, quercitrin, and astragalin on iron bioavailability suggest that the 3',4'-dihydroxy group on the B-ring in flavonoids contributes to the lower iron bioavailability. PMID:17117818

Hu, Ying; Cheng, Zhiqiang; Heller, Larry I; Krasnoff, Stuart B; Glahn, Raymond P; Welch, Ross M

2006-11-29

119

Improved performance of CdS/CdSe quantum dots sensitized solar cell by incorporation of ZnO nanoparticles/reduced graphene oxide nanocomposite as photoelectrode  

NASA Astrophysics Data System (ADS)

Here we present novel quantum dot sensitized solar cells (QDSSC) based on ZnO nanoparticles (NPs)/reduced graphene oxide (RGO) nanocomposite photoanodes for better light harvesting and energy conversion. Photoelectrodes are prepared by doctor blading ZnO NPs/GO nanocomposite paste on a fluorine doped tin oxide substrate which are then sintered at 450蚓 to obtain ZnO NPs/RGO nanocomposites. The partial reduction of GO after thermal reduction, is studied by Fourier transform infrared and Raman spectroscopies. Cadmium sulfide (CdS) and cadmium selenide (CdSe) quantum dots are deposited on the films through successive ionic layer adsorption and reaction and chemical bath deposition methods, respectively. The unique properties of ZnO NPs/RGO photoanodes, lead to a significant enhancement in the photovoltaic properties of solar cells in comparison with bare ZnO photoanodes. Current-voltage characteristics of cells are studied and the best results are obtained from ZnO NPs-RGO/CdS/CdSe with photoelectric conversion efficiency of 2.20% which is almost two times higher than cells which are made by pure ZnO NPs as photoanode (1.28%). Electrochemical impedance measurements show that the enhancement can be attributed to the increase of electron transfer rate in the ZnO NPs/RGO nanocomposite photoanode which arises from the ultrahigh electron mobility in graphene (RGO) sheets.

Ghoreishi, F. S.; Ahmadi, V.; Samadpour, M.

2014-12-01

120

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

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

121

Site-specific incorporation of three toll-like receptor 2 targeting adjuvants into semisynthetic, molecularly defined nanoparticles: application to group a streptococcal vaccines.  

PubMed

Subunit vaccines offer a means to produce safer, more defined vaccines compared to traditional whole microorganism approaches. Subunit antigens, however, exhibit weak immunity, which is normally overcome through coadministration with adjuvants. Enhanced vaccine properties (e.g., improved potency) can be obtained by linking antigen and adjuvant, as observed for synthetic peptide antigens and Toll-like receptor 2 (TLR2) ligands. As few protective peptide antigens have been reported, compared to protein antigens, we sought to extend the utility of this approach to recombinant proteins, while ensuring that conjugation reactions yielded a single, molecularly defined product. Herein we describe the development and optimization of techniques that enable the efficient, site-specific attachment of three synthetic TLR2 ligands (lipid core peptide (LCP), Pam2Cys, and Pam3Cys) onto engineered protein antigens, permitting the selection of optimal TLR2 agonists during the vaccine development process. Using this approach, broadly protective (J14) and population targeted (seven M protein N-terminal antigens) multiantigenic vaccines against group A streptococcus (GAS; Streptococcus pyogenes) were produced and observed to self-assemble in PBS to yield nanoparticules (69, 101, and 123 nm, respectively). All nanoparticle formulations exhibited self-adjuvanting properties, with rapid, persistent, antigen-specific IgG antibody responses elicited toward each antigen in subcutaneously immunized C57BL/6J mice. These antibodies were demonstrated to strongly bind to the cell surface of five GAS serotypes that are not represented by vaccine M protein N-terminal antigens, are among the top 20 circulating strains in developed countries, and are associated with clinical disease, suggesting that these vaccines may elicit broadly protective immune responses. PMID:24712905

Moyle, Peter M; Dai, Wei; Zhang, Yingkai; Batzloff, Michael R; Good, Michael F; Toth, Istvan

2014-05-21

122

Characterization of a glucosyltransferase enzyme involved in the formation of kaempferol and quercetin sophorosides in Crocus sativus.  

PubMed

UGT707B1 is a new glucosyltransferase isolated from saffron (Crocus sativus) that localizes to the cytoplasm and the nucleus of stigma and tepal cells. UGT707B1 transcripts were detected in the stigma tissue of all the Crocus species analyzed, but expression analysis of UGT707B1 in tepals revealed its absence in certain species. The analysis of the glucosylated flavonoids present in Crocus tepals reveals the presence of two major flavonoid compounds in saffron: kaempferol-3-O-?-D-glucopyranosyl-(1-2)-?-D-glucopyranoside and quercetin-3-O-?-D-glucopyranosyl-(1-2)-?-D-glucopyranoside, both of which were absent from the tepals of those Crocus species that did not express UGT707B1. Transgenic Arabidopsis (Arabidopsis thaliana) plants constitutively expressing UGT707B1 under the control of the cauliflower mosaic virus 35S promoter have been constructed and their phenotype analyzed. The transgenic lines displayed a number of changes that resembled those described previously in lines where flavonoid levels had been altered. The plants showed hyponastic leaves, a reduced number of trichomes, thicker stems, and flowering delay. Levels of flavonoids measured in extracts of the transgenic plants showed changes in the composition of flavonols when compared with wild-type plants. The major differences were observed in the extracts from stems and flowers, with an increase in 3-sophoroside flavonol glucosides. Furthermore, a new compound not detected in ecotype Columbia wild-type plants was detected in all the tissues and identified as kaempferol-3-O-sophoroside-7-O-rhamnoside. These data reveal the involvement of UGT707B1 in the biosynthesis of flavonol-3-O-sophorosides and how significant changes in flavonoid homeostasis can be caused by the overproduction of a flavonoid-conjugating enzyme. PMID:22649274

Trapero, Almudena; Ahrazem, Oussama; Rubio-Moraga, Angela; Jimeno, Maria Luisa; G鏔ez, Maria Dolores; G鏔ez-G鏔ez, Lourdes

2012-08-01

123

Effects of the flavonoids kaempferol and fisetin on thermotolerance, oxidative stress and FoxO transcription factor DAF-16 in the model organism Caenorhabditis elegans.  

PubMed

Flavonoids present in many herbal edibles possess a remarkable spectrum of biochemical and pharmacological actions and they are assumed to exert beneficial effects to human health. Although the precise biological mechanisms of their action has not been elucidated yet many of the protective properties of flavonoids are attributed to their antioxidative activity since oxidative stress is regarded as a main factor in the pathophysiology of various diseases and ageing. Oxidative stress results from excessive generation of reactive oxygen species (ROS) or diminished antioxidative defence and thus antioxidants are able to counteract such situations. We used the multicellular model organism Caenorhabditis elegans that is conserved in molecular and cellular pathways to mammals to examine the effects of the flavonoids kaempferol and fisetin with respect to their protective action in individual living worms. Both flavonoids increased the survival of C. elegans, reduced the intracellular ROS accumulation at lethal thermal stress, and diminished the extent of induced oxidative stress with kaempferol having a stronger impact. Kaempferol but not fisetin attenuated the accumulation of the ageing marker lipofuscin suggesting a life prolonging activity of this flavonoid. In addition to these effects that may be attributed to their antioxidative potential kaempferol and fisetin caused a translocation of the C. elegans FoxO transcription factor DAF-16 from the cytosol to the nucleus indicating a modulatory influence of both flavonoids on signalling cascade(s). PMID:17551714

Kampk飆ter, Andreas; Gombitang Nkwonkam, Christiane; Zurawski, Ruben Felix; Timpel, Claudia; Chovolou, Yvonni; W酹jen, Wim; Kahl, Regine

2007-12-01

124

Solidphase extraction and gas chromatographymass spectrometry determination of kaempferol and quercetin in human urine after consumption of Ginkgo biloba tablets  

Microsoft Academic Search

A method was developed for the quantification of the flavonoids quercetin and kaempferol in human urine using a solid-phase extraction procedure followed by gas chromatographymass spectrometry. Deuterated internal standards of the analytes were spiked into the samples prior to extraction. The limit of detection of the method was ca. 10 pg on column and precision of the method for quantification

D. G. Watson; E. J. Oliveira

1999-01-01

125

Transcriptional profiling in human HaCaT keratinocytes in response to kaempferol and identification of potential transcription factors for regulating differential gene expression  

PubMed Central

Kaempferol is the major flavonol in green tea and exhibits many biomedically useful properties such as antioxidative, cytoprotective and anti-apoptotic activities. To elucidate its effects on the skin, we investigated the transcriptional profiles of kaempferol-treated HaCaT cells using cDNA microarray analysis and identified 147 transcripts that exhibited significant changes in expression. Of these, 18 were up-regulated and 129 were down-regulated. These transcripts were then classified into 12 categories according to their functional roles: cell adhesion/cytoskeleton, cell cycle, redox homeostasis, immune/defense responses, metabolism, protein biosynthesis/modification, intracellular transport, RNA processing, DNA modification/ replication, regulation of transcription, signal transduction and transport. We then analyzed the promoter sequences of differentially-regulated genes and identified over-represented regulatory sites and candidate transcription factors (TFs) for gene regulation by kaempferol. These included c-REL, SAP-1, Ahr-ARNT, Nrf-2, Elk-1, SPI-B, NF-?B and p65. In addition, we validated the microarray results and promoter analyses using conventional methods such as real-time PCR and ELISA-based transcription factor assay. Our microarray analysis has provided useful information for determining the genetic regulatory network affected by kaempferol, and this approach will be useful for elucidating gene-phytochemical interactions. PMID:18446059

Kang, Byung Young; Lee, Ki-Hwan; Lee, Yong Sung; Hong, Il; Lee, Mi-Ock; Min, Daejin; Chang, Ihseop; Hwang, Jae Sung; Park, Jun Seong; Kim, Duck Hee

2008-01-01

126

Effects of silver ions and nanoparticles on suspended cells and biofilms of Nitrosomonas europaea.  

E-print Network

??Silver nanoparticles are increasingly being incorporated into consumer products due to their broad-spectrum antimicrobial properties. The resulting influx of silver nanoparticles into wastewater may pose (more)

Barker, Leila Kelly

2014-01-01

127

Cytoprotective effect of kaempferol on paraquat-exposed BEAS-2B cells via modulating expression of MUC5AC.  

PubMed

Mucins are highly glycosylated secretary proteins produced by most epithelial cells. Hypersecretion of mucins is one of the prominent symptoms of several airway diseases, including asthma, cystic fibrosis, nasal allergy, rhinitis, and sinusitis. Paraquat (PQ), a common herbicide, has been associated with pulmonary damage and is a potent reactive oxygen species (ROS) producer. However, until now the role of PQ on mucin overproduction has not been studied. The aim of this study is to explore how kaempferol (KM), a widely used dietary flavonoid, affects the protection of human PQ-exposed bronchial epithelium BEAS-2B cells by suppressing Mucin gene expression via nuclear factor-kappa B (NF-?B). We observed that PQ generates intracellular ROS, and also induces lipid peroxidation in BEAS-2B cells. Additionally, we found that PQ effectively induces the expression of the MUC5AC gene; however, co-treatment of PQ with KM drastically reduces its expression. Furthermore, we observed that PQ activates NF-?B, while co-treatment with KM occludes its nuclear translocation, and additionally KM repressed the PQ phosphorylation of c-Jun N-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK) in BEAS-2B cells. Based on our data, we believe that KM can suppress the over-expression of the MUC5AC gene. This would contribute to the protection of PQ cytotoxicity to exposed BEAS-2B cells, and allow further study toward a better understanding of ROS-associated diseases. PMID:25177032

Podder, Biswajit; Song, Kyoung Seob; Song, Ho-Yeon; Kim, Yong-Sik

2014-01-01

128

Synthesis, Characterization, DNA Interaction, and Antitumor Activities of La (III) Complex with Schiff Base Ligand Derived from Kaempferol and Diethylenetriamine  

PubMed Central

A novel La (III) complex, [LaL(H2O)3]NO33H2O, with Schiff base ligand L derived from kaempferol and diethylenetriamine, has been synthesized and characterized by elemental analysis, IR, UV-visible, 1H NMR, thermogravimetric analysis, and molar conductance measurements. The fluorescence spectra, circular dichroism spectra, and viscosity measurements and gel electrophoresis experiments indicated that the ligand L and La (III) complex could bind to CT-DNA presumably via intercalative mode and the La (III) complex showed a stronger ability to bind and cleave DNA than the ligand L alone. The binding constants (Kb) were evaluated from fluorescence data and the values ranged from 0.454 to 0.659 105 L mol?1 and 1.71 to 17.3 105 L mol?1 for the ligand L and La (III) complex, respectively, in the temperature range of 298310?K. It was also found that the fluorescence quenching mechanism of EB-DNA by ligand L and La (III) complex was a static quenching process. In comparison to free ligand L, La (III) complex exhibited enhanced cytotoxic activities against tested tumor cell lines HL-60 and HepG-2, which may correlate with the enhanced DNA binding and cleaving abilities of the La (III) complex. PMID:25371657

Wang, Qin; Huang, Yu; Zhang, Jin-Sheng; Yang, Xin-Bin

2014-01-01

129

Separation of quercetin, sexangularetin, kaempferol and isorhamnetin for simultaneous HPLC determination of flavonoid aglycones in inflorescences, leaves and fruits of three Sorbus species  

Microsoft Academic Search

A reversed-phase high-performance liquid chromatographic (RP-HPLC) method was developed and validated for the simultaneous determination of four flavonol aglycones (quercetin, QU; sexangularetin, SX; kaempferol, KA; isorhamnetin, IS) in hydrolyzed extracts from different plant parts of Sorbus aucuparia L., Sorbus aria (L.) Crantz. and Sorbus intermedia (Ehrh.) Pers. Separation of the four compounds was accomplished on a C18 Lichrosphere 100 column

Monika Olszewska

2008-01-01

130

Pharmacokinetic properties of isorhamnetin, kaempferol and quercetin after oral gavage of total flavones of Hippophae rhamnoides L. in rats using a UPLCMS method  

Microsoft Academic Search

An ultra performance liquid chromatographymass spectrometric (UPLCMS) method was developed to investigate the pharmacokinetic properties of isorhamnetin, kaempferol and quercetin from a total flavone extract of Hippophae rhamnoides L. (TFH) after single dose oral administration. Rat plasma samples were pretreated using liquidliquid extraction, and chromatographic separation was performed on a C18 column using a linear gradient of methanol and formic

Guowen Li; Xiaoli Zeng; Yan Xie; Zhenzhen Cai; Jeffrey C. Moore; Xiurong Yuan; Zhihong Cheng; Guang Ji

131

Effect of Ginkgo biloba extract on procarcinogen-bioactivating human CYP1 enzymes: Identification of isorhamnetin, kaempferol, and quercetin as potent inhibitors of CYP1B1  

SciTech Connect

In the present study, we investigated the effect of Ginkgo biloba extracts and some of its individual constituents on the catalytic activity of human cytochrome P450 enzymes CYP1B1, CYP1A1, and CYP1A2. G. biloba extract of known abundance of terpene trilactones and flavonol glycosides inhibited 7-ethoxyresorufin O-dealkylation catalyzed by human recombinant CYP1B1, CYP1A1, and CYP1A2, and human liver microsomes, with apparent K {sub i} values of 2 {+-} 0.3, 5 {+-} 0.5, 16 {+-} 1.4, and 39 {+-} 1.2 {mu}g/ml (mean {+-} SE), respectively. In each case, the mode of inhibition was of the mixed type. Bilobalide, ginkgolides A, B, C, and J, quercetin 3-O-rutinoside, kaempferol 3-O-rutinoside, and isorhamentin 3-O-rutinoside were not responsible for the inhibition of CYP1 enzymes by G. biloba extract, as determined by experiments with these individual chemicals at the levels present in the extract. In contrast, the aglycones of quercetin, kaempferol, and isorhamentin inhibited CYP1B1, CYP1A1, and CYP1A2. Among the three flavonol aglycones, isorhamentin was the most potent in inhibiting CYP1B1 (apparent K {sub i} = 3 {+-} 0.1 nM), whereas quercetin was the least potent in inhibiting CYP1A2 (apparent K {sub i} 418 {+-} 50 nM). The mode of inhibition was competitive, noncompetitive, or mixed, depending on the enzyme and the flavonol. G. biloba extract also reduced benzo[a]pyrene hydroxylation, and the effect was greater with CYP1B1 than with CYP1A1 as the catalyst. Overall, our novel findings indicate that G. biloba extract and the flavonol aglycones isorhamnetin, kaempferol, and quercetin preferentially inhibit the in vitro catalytic activity of human CYP1B1.

Chang, Thomas K.H. [Faculty of Pharmaceutical Sciences, University of British Columbia, 2146 East Mall, Vancouver, BC, V6T 1Z3 (Canada)]. E-mail: tchang@interchange.ubc.ca; Chen Jie [Faculty of Pharmaceutical Sciences, University of British Columbia, 2146 East Mall, Vancouver, BC, V6T 1Z3 (Canada); Yeung, Eugene Y.H. [Faculty of Pharmaceutical Sciences, University of British Columbia, 2146 East Mall, Vancouver, BC, V6T 1Z3 (Canada)

2006-05-15

132

Nanoparticles for imaging: top or flop?  

PubMed

Nanoparticles are frequently suggested as diagnostic agents. However, except for iron oxide nanoparticles, diagnostic nanoparticles have been barely incorporated into clinical use so far. This is predominantly due to difficulties in achieving acceptable pharmacokinetic properties and reproducible particle uniformity as well as to concerns about toxicity, biodegradation, and elimination. Reasonable indications for the clinical utilization of nanoparticles should consider their biologic behavior. For example, many nanoparticles are taken up by macrophages and accumulate in macrophage-rich tissues. Thus, they can be used to provide contrast in liver, spleen, lymph nodes, and inflammatory lesions (eg, atherosclerotic plaques). Furthermore, cells can be efficiently labeled with nanoparticles, enabling the localization of implanted (stem) cells and tissue-engineered grafts as well as in vivo migration studies of cells. The potential of using nanoparticles for molecular imaging is compromised because their pharmacokinetic properties are difficult to control. Ideal targets for nanoparticles are localized on the endothelial luminal surface, whereas targeted nanoparticle delivery to extravascular structures is often limited and difficult to separate from an underlying enhanced permeability and retention (EPR) effect. The majority of clinically used nanoparticle-based drug delivery systems are based on the EPR effect, and, for their more personalized use, imaging markers can be incorporated to monitor biodistribution, target site accumulation, drug release, and treatment efficacy. In conclusion, although nanoparticles are not always the right choice for molecular imaging (because smaller or larger molecules might provide more specific information), there are other diagnostic and theranostic applications for which nanoparticles hold substantial clinical potential. PMID:25247562

Kiessling, Fabian; Mertens, Marianne E; Grimm, Jan; Lammers, Twan

2014-10-01

133

Nanoparticles for Imaging: Top or Flop?  

PubMed Central

Nanoparticles are frequently suggested as diagnostic agents. However, except for iron oxide nanoparticles, diagnostic nanoparticles have been barely incorporated into clinical use so far. This is predominantly due to difficulties in achieving acceptable pharmacokinetic properties and reproducible particle uniformity as well as to concerns about toxicity, biodegradation, and elimination. Reasonable indications for the clinical utilization of nanoparticles should consider their biologic behavior. For example, many nanoparticles are taken up by macrophages and accumulate in macrophage-rich tissues. Thus, they can be used to provide contrast in liver, spleen, lymph nodes, and inflammatory lesions (eg, atherosclerotic plaques). Furthermore, cells can be efficiently labeled with nanoparticles, enabling the localization of implanted (stem) cells and tissue-engineered grafts as well as in vivo migration studies of cells. The potential of using nanoparticles for molecular imaging is compromised because their pharmacokinetic properties are difficult to control. Ideal targets for nanoparticles are localized on the endothelial luminal surface, whereas targeted nanoparticle delivery to extravascular structures is often limited and difficult to separate from an underlying enhanced permeability and retention (EPR) effect. The majority of clinically used nanoparticle-based drug delivery systems are based on the EPR effect, and, for their more personalized use, imaging markers can be incorporated to monitor biodistribution, target site accumulation, drug release, and treatment efficacy. In conclusion, although nanoparticles are not always the right choice for molecular imaging (because smaller or larger molecules might provide more specific information), there are other diagnostic and theranostic applications for which nanoparticles hold substantial clinical potential. PMID:25247562

Kiessling, Fabian; Mertens, Marianne E.; Grimm, Jan; Lammers, Twan

2014-01-01

134

Carbon Materials Metal/Metal Oxide Nanoparticle Composite and Battery Anode Composed of the Same  

NASA Technical Reports Server (NTRS)

A method of forming a composite material for use as an anode for a lithium-ion battery is disclosed. The steps include selecting a carbon material as a constituent part of the composite, chemically treating the selected carbon material to receive nanoparticles, incorporating nanoparticles into the chemically treated carbon material and removing surface nanoparticles from an outside surface of the carbon material with incorporated nanoparticles. A material making up the nanoparticles alloys with lithium.

Hung, Ching-Cheh (Inventor)

2006-01-01

135

Optimization of crystalline tungsten oxide nanoparticles for improved electrochromic applications  

Microsoft Academic Search

The high-density synthesis of crystalline tungsten oxide nanoparticles employing hot-wire chemical vapor deposition (HWCVD) and enhancement in electrochromic (EC) performance by incorporating these nanoparticles into porous films has been previously reported. Here varying the oxygen concentration during the HWCVD synthesis of these crystalline tungsten oxide (WOx) nanoparticles is examined in order to better understand the mechanism for the improvement in

R. Deshpande; S.-H. Lee; A. H. Mahan; P. A. Parilla; K. M. Jones; A. G. Norman; B. To; J. L. Blackburn; S. Mitra; A. C. Dillon

2007-01-01

136

Metal-doped semiconductor nanoparticles and methods of synthesis thereof  

NASA Technical Reports Server (NTRS)

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

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

2009-01-01

137

Nanoparticle Assembly DOI: 10.1002/anie.201006231  

E-print Network

labeled with a fluorescent dye. Rhodamine 6G was incorporated by physical adsorption and subsequentNanoparticle Assembly DOI: 10.1002/anie.201006231 Silica-Nanoparticle Coatings by Adsorption from] enables multiple biological applications includ- ing dye-doped nanoparticles for cell imaging,[7] drug

Kokkoli, Efie

138

Bioassay-guided isolation of kaempferol-3-O-beta-D-galactoside with anti-inflammatory and antinociceptive activity from the aerial part of Calluna vulgaris L.  

PubMed

Calluna vulgaris L. (Ericaceae) is used for the treatment of various inflammatory ailments in traditional medicines. In order to evaluate this ethnobotanical information, its anti-inflammatory and antinociceptive activities were studied using in vivo experimental models in mice. The ethanolic extract of the plant was first fractionated into five extracts; namely, n-hexane, chloroform, ethyl acetate (EtOAc), n-butanol, and water fractions. Among them, the EtOAc Fr. was found to be the most effective and was further subjected to bioassay-guided fractionation and isolation procedures. After successive column chromatography applications, on Sephadex LH-20 and silica gel, a component, which is responsible for the above-mentioned activities of this species of Turkish origin, was isolated and its structure was elucidated as kaempferol-3-O-beta-D-galactoside, a common flavonol derivative by means of spectral techniques. PMID:17765419

Orhan, I; Kpeli, E; Terzio?lu, S; Yesilada, E

2007-10-01

139

Characterization of a Glucosyltransferase Enzyme Involved in the Formation of Kaempferol and Quercetin Sophorosides in Crocus sativus1[C][W  

PubMed Central

UGT707B1 is a new glucosyltransferase isolated from saffron (Crocus sativus) that localizes to the cytoplasm and the nucleus of stigma and tepal cells. UGT707B1 transcripts were detected in the stigma tissue of all the Crocus species analyzed, but expression analysis of UGT707B1 in tepals revealed its absence in certain species. The analysis of the glucosylated flavonoids present in Crocus tepals reveals the presence of two major flavonoid compounds in saffron: kaempferol-3-O-?-d-glucopyranosyl-(1-2)-?-d-glucopyranoside and quercetin-3-O-?-d-glucopyranosyl-(1-2)-?-d-glucopyranoside, both of which were absent from the tepals of those Crocus species that did not express UGT707B1. Transgenic Arabidopsis (Arabidopsis thaliana) plants constitutively expressing UGT707B1 under the control of the cauliflower mosaic virus 35S promoter have been constructed and their phenotype analyzed. The transgenic lines displayed a number of changes that resembled those described previously in lines where flavonoid levels had been altered. The plants showed hyponastic leaves, a reduced number of trichomes, thicker stems, and flowering delay. Levels of flavonoids measured in extracts of the transgenic plants showed changes in the composition of flavonols when compared with wild-type plants. The major differences were observed in the extracts from stems and flowers, with an increase in 3-sophoroside flavonol glucosides. Furthermore, a new compound not detected in ecotype Columbia wild-type plants was detected in all the tissues and identified as kaempferol-3-O-sophoroside-7-O-rhamnoside. These data reveal the involvement of UGT707B1 in the biosynthesis of flavonol-3-O-sophorosides and how significant changes in flavonoid homeostasis can be caused by the overproduction of a flavonoid-conjugating enzyme. PMID:22649274

Trapero, Almudena; Ahrazem, Oussama; Rubio-Moraga, Angela; Jimeno, Maria Luisa; Gomez, Maria Dolores; Gomez-Gomez, Lourdes

2012-01-01

140

Neuroprotective Effect of Kaempferol Glycosides against Brain Injury and Neuroinflammation by Inhibiting the Activation of NF-?B and STAT3 in Transient Focal Stroke  

PubMed Central

Background Ischemic brain injury is associated with neuroinflammatory response, which essentially involves glial activation and neutrophil infiltration. Transcription factors nuclear factor-?B (NF-?B) and signal transducer and activator of transcription 3 (STAT3) contribute to ischemic neuroinflammatory processes and secondary brain injury by releasing proinflammatory mediators. Kaempferol-3-O-rutinoside (KRS) and kaempferol-3-O- glucoside (KGS) are primary flavonoids found in Carthamus tinctorius L. Recent studies demonstrated that KRS protected against ischemic brain injury. However, little is known about the underlying mechanisms. Flavonoids have been reported to have antiinflammatory properties. Herein, we explored the effects of KRS and KGS in a transient focal stroke model. Methodology/Principal Findings Rats were subjected to middle cerebral artery occlusion for 2 hours followed by 22 h reperfusion. An equimolar dose of KRS or KGS was administered i.v. at the beginning of reperfusion. The results showed that KRS or KGS significantly attenuated the neurological deficits, brain infarct volume, and neuron and axon injury, reflected by the upregulation of neuronal nuclear antigen-positive neurons and downregulation of amyloid precursor protein immunoreactivity in the ipsilateral ischemic hemisphere. Moreover, KRS and KGS inhibited the expression of OX-42, glial fibrillary acidic protein, phosphorylated STAT3 and NF-?B p65, and the nuclear content of NF-?B p65. Subsequently, these flavonoids inhibited the expression of tumor necrosis factor ?, interleukin 1?, intercellular adhesion molecule 1, matrix metallopeptidase 9, inducible nitric oxide synthase, and myeloperoxidase. Conclusion/Significance Our findings suggest that postischemic treatment with KRS or KGS prevents ischemic brain injury and neuroinflammation by inhibition of STAT3 and NF-?B activation and has the therapeutic potential for the neuroinflammation-related diseases, such as ischemic stroke. PMID:23437066

Wang, Liang-Fen; Kuang, Xi; Liu, Ke; Zhang, Hao; Du, Jun-Rong

2013-01-01

141

Development of molecular indicators to track the effects of nanoparticle toxicity in Arabidopsis thaliana  

EPA Science Inventory

The emergence of nanotechnology and incorporation of nanoparticles in consumer products necessitates risk assessment from an environmental and health safety standpoint. To date, very few studies have examined nanoparticle effects on terrestrial species, especially plants. Pre...

142

In Vitro Toxicity of Silver Nanoparticles in Human Lung Epithelial Cells.  

National Technical Information Service (NTIS)

Nanotechnology is quickly becoming incorporated into everyday products and uses. Silver nanoparticles, specifically, are being used in commercial products, to include aerosols. The purpose of this research was to determine whether silver nanoparticles are...

C. R. Kearns

2009-01-01

143

Nanoparticle PEGylation for imaging and therapy  

PubMed Central

Nanoparticles are an essential component in the emerging field of nanomedical imaging and therapy. When deployed in vivo, these materials are typically protected from the immune system by polyethylene glycol (PEG). A wide variety of strategies to coat and characterize nanoparticles with PEG has established important trends on PEG size, shape, density, loading level, molecular weight, charge and purification. Strategies to incorporate targeting ligands are also prevalent. This article presents a background to investigators new to stealth nanoparticles, and suggests some key considerations needed prior to designing a nanoparticle PEGylation protocol and characterizing the performance features of the product. PMID:21718180

Jokerst, Jesse V; Lobovkina, Tatsiana; Zare, Richard N; Gambhir, Sanjiv S

2011-01-01

144

Engineering nanoparticle-protein associations for protein crystal nucleation and nanoparticle arrangement  

NASA Astrophysics Data System (ADS)

Engineering the nanoparticle - protein association offers a new way to form protein crystals as well as new approaches for arrangement of nanoparticles. Central to this control is the nanoparticle surface. By conjugating polymers on the surface with controlled molecular weights many properties of the nanoparticle can be changed including its size, stability in buffers and the association of proteins with its surface. Large molecular weight poly(ethylene glycol) (PEG) coatings allow for weak associations between proteins and nanoparticles. These interactions can lead to changes in how proteins crystallize. In particular, they decrease the time to nucleation and expand the range of conditions over which protein crystals form. Interestingly, when PEG chain lengths are too short then protein association is minimized and these effects are not observed. One important feature of protein crystals nucleated with nanoparticles is that the nanoparticles are incorporated into the crystals. What results are nanoparticles placed at well-defined distances in composite protein-nanoparticle crystals. Crystals on the size scale of 10 - 100 micrometers exhibit optical absorbance, fluorescence and super paramagnetic behavior derivative from the incorporated nanomaterials. The arrangement of nanoparticles into three dimensional arrays also gives rise to new and interesting physical and chemical properties, such as fluorescence enhancement and varied magnetic response. In addition, anisotropic nanomaterials aligned throughout the composite crystal have polarization dependent optical properties.

Benoit, Denise N.

145

Baroplastic core-shell nanoparticles  

NASA Astrophysics Data System (ADS)

A novel class of baroplastic core-shell nanoparticles was designed based on the pressure-induced miscibility between a low Tg component core and a high Tg component shell and obtained by a two-stage miniemulsion polymerization technique. By changing the amount of surfactant and monomer feed ratio, the size and composition of core-shell nanoparticles were controlled and almost homogenous particles with very narrow particle size distribution were obtained in each synthetic step. Trilayerd core-shell nanoparticles, which have an additional inner-core, were also successfully synthesized by sequential addition of monomers. The baroplasticity of these core-shell nanoparticles was demonstrated by compression molding and characterized by SANS, DSC, and TEM. Transparent objects were molded at temperatures as low as 25 oC under 5000 psi pressure, and recycled up to 10 times, from poly(n-butyl acrylate)/polystyrene or poly(2-ethyl hexyl acrylate)/polystyrene systems. The particle size was found to play an important role to determine the optical and mechanical properties of the resulting product. By comparison with bilayered core-shell nanoparticles, improved mechanical properties were observed in trilayered systems due to the enlarged interface region. Finally, blend or hybrid baroplastic core-shell nanoparticles were prepared incorporating other polymer or inorganic nanoparticles.

Woog Ryu, Sang; Gonzalez, Juan; Acar, Metin; Mayes, Anne

2004-03-01

146

Application of Magnetic Nanoparticles to Gene Delivery  

PubMed Central

Nanoparticle technology is being incorporated into many areas of molecular science and biomedicine. Because nanoparticles are small enough to enter almost all areas of the body, including the circulatory system and cells, they have been and continue to be exploited for basic biomedical research as well as clinical diagnostic and therapeutic applications. For example, nanoparticles hold great promise for enabling gene therapy to reach its full potential by facilitating targeted delivery of DNA into tissues and cells. Substantial progress has been made in binding DNA to nanoparticles and controlling the behavior of these complexes. In this article, we review research on binding DNAs to nanoparticles as well as our latest study on non-viral gene delivery using polyethylenimine-coated magnetic nanoparticles. PMID:21747701

Kami, Daisuke; Takeda, Shogo; Itakura, Yoko; Gojo, Satoshi; Watanabe, Masatoshi; Toyoda, Masashi

2011-01-01

147

CORPORATIONS APAC Tennessee Incorporated  

E-print Network

and Associates Diversified Financial Group LLC Dixon Hughes Goodman LLP Donaldson Capital Management LLC Dorris Engineers' Club of Memphis Incorporated Ernst and Young LLP Eyewear Gallery Farris Bobango PLLC Fastech Pavilion Memphis Incorporated Funding Factory WLOK Radio Gipson Specialty Center PLLC Glankler Brown PLLC

Dasgupta, Dipankar

148

GENDER EQUALITY Incorporated  

E-print Network

, gender roles, gender construction Gender mythsGENDER EQUALITY Incorporated 5 DAY GENDER TRAINING WITH CERTIFICATION April 26-30, 2010 - Toronto. #12;simplifying IT 5 DAY GENDER TRAINING WITH CERTIFICATION GOAL This 5 day course is designed

Barthelat, Francois

149

Fluorescent Nanoparticles  

NSDL National Science Digital Library

This site from Clemson University shows how fluorescence enables the tracking of nanoparticles in living cells. Illustrations include the fluorescence of different kinds of nanoparticles, close-up views of the fluorescent particles, and the fluorescent particles as seen within cells.

Mcneill, Jason

2008-04-16

150

Investigations of nano-particle toxicity and uptake of Cerium oxide and Titanium dioxide in Arabidopsis thaliana (L.)  

EPA Science Inventory

The emergence of nanotechnology and incorporation of nanoparticles in consumer products necessitates risk assessment from an environmental and health safety standpoint. To date, very few studies have examined nanoparticle effects on terrestrial species, especially plants. In ...

151

Separation of quercetin, sexangularetin, kaempferol and isorhamnetin for simultaneous HPLC determination of flavonoid aglycones in inflorescences, leaves and fruits of three Sorbus species.  

PubMed

A reversed-phase high-performance liquid chromatographic (RP-HPLC) method was developed and validated for the simultaneous determination of four flavonol aglycones (quercetin, QU; sexangularetin, SX; kaempferol, KA; isorhamnetin, IS) in hydrolyzed extracts from different plant parts of Sorbus aucuparia L., Sorbus aria (L.) Crantz. and Sorbus intermedia (Ehrh.) Pers. Separation of the four compounds was accomplished on a C18 Lichrosphere 100 column (5 microm, 250 mm x 4.6mm, i.d.) with a methanol gradient elution and recorded at 370 nm. The high resolution of critical bands - SX, KA and IS - was achieved with retention of the last peak (IS) in 19.5 min. The equilibration of the standard mixture by addition of HCl to an acid concentration equal that of hydrolyzed extracts injected was found to be necessary when minimizing calibration error. The correlation coefficients of all the calibration curves showed good linearity (r>0.9991) over the test range. The relative standard deviation of the method was less than 2.8% for intra- and inter-day assays, and the average recoveries were between 95.5 and 102.5%. High sensitivity was demonstrated with detection limits between 0.050 and 0.085 microg/ml. The level of total aglycones was found to be in the range of 687-1,515 mg/100g of dry weight in the inflorescences, 424-1,078 mg/100g in the leaves and 20-60 mg/100g in the fruits depending on the Sorbus species. PMID:18635332

Olszewska, Monika

2008-11-01

152

The flavonols quercetin, myricetin, kaempferol, and galangin inhibit the net oxygen consumption by immune complex-stimulated human and rabbit neutrophils.  

PubMed

Stimulated human neutrophils exhibit increased net oxygen consumption (NOC) due to the conversion of O2 into the superoxide anion by the NADPH oxidase enzymatic complex during the respiratory burst. In several inflammatory diseases, overproduction of these oxidants causes tissue damage. The present study aims to: (a) optimize the experimental conditions used to measure the NOC in serum-opsonized zymosan (OZ)- and insoluble immune complex (i-IC)-stimulated human and rabbit neutrophils; and (b) compare the effect of four flavonols (quercetin, myricetin, kaempferol, and galangin) on this activity. We used a Clark-type oxygen electrode to measure the NOC of stimulated neutrophils. Eliciting the neutrophil respiratory burst with OZ and i-IC yielded similar maximum O2 uptake levels within the same species, but the human neutrophil NOC was almost four times higher than the rabbit neutrophil NOC. The optimal experimental conditions established for both cell types were 4 x 10(6) neutrophils mL(-1), 2 mg mL(-1) OZ, and 240 microg mL(-1) i-IC. Upon stimulation with OZ or i-IC, the tested flavonols reduced the human and rabbit neutrophil NOC in the same order of potency--quercetin and galangin were the most and the least potent, respectively. These compounds were around four times more effective in inhibiting the rabbit as compared to the human neutrophil NOC, respectively. The four flavonols were not toxic to human or rabbit neutrophils. The experimental conditions used are suitable for both the determination of human and rabbit neutrophil NOC and for the assessment of the modulatory effects of natural compounds on these activities. The relationship between the level of NOC and the inhibitory potency of the flavonols suggests that rabbit neutrophils can be useful experimental models to predict the effect of drugs on immune complex-stimulated human neutrophils. PMID:25265855

Figueiredo-Rinhel, Andr嶧 S G; Santos, Everton O L; Kabeya, Luciana M; Azzolini, Ana Elisa C S; Sim髊s-Ambrosio, Livia M C; Lucisano-Valim, Yara M

2014-01-01

153

Electrochemiluminescent metallopolymer-nanoparticle composites: nanoparticle size effects.  

PubMed

Metallopolymer-gold nanocomposites have been synthesized in which the metal complex-Au nanoparticle (NP) mole ratio is systematically varied by mixing solutions of 4-(dimethylamino) pyridine protected gold nanoparticles and a [Ru(bpy)(2)PVP(10)](2+) metallopolymer; bpy is 2,2'-bipyridyl and PVP is poly-(4-vinylpyridine). The impact of changing the gold nanoparticle diameter ranging from 4.0 0.5 to 12.5 1 nm has been investigated. The photo induced emission of the metallopolymer undergoes static quenching by the metal nanoparticles irrespective of their size. When the volume ratio of Au NP-Ru is 1, the quenching efficiency increases from 38% to 93% on going from 4.0 0.5 to 12.5 1 nm diameter nanoparticles while the radius of the quenching sphere remains unaffected at 75 5 . The conductivity of thin films is initially unaffected by nanoparticle incorporation until a percolation threshold is reached at a mole ratio of 4.95 10(-2) after which the conductivity increases before reaching a maximum. For thin films of the nanocomposites on electrodes, the electrochemiluminescence intensity of the nanocomposite initially increases as nanoparticles are added before decreasing for the highest loadings. The electrochemiluminescence intensity increases with increasing nanoparticle diameter. The electrochemiluminescence (ECL) emission intensity of the nanocomposite formed using 12.5 nm particles at mole ratios between 5 10(-3) and 10 10(-3) is approximately 7-fold higher than that found for the parent metallopolymer. The application of these materials for low cost ECL-based point of care devices is discussed. PMID:21361366

Devadoss, Anitha; Dickinson, Calum; Keyes, Tia E; Forster, Robert J

2011-03-15

154

Preparation of Silica Microspheres Containing Ag Nanoparticles  

Microsoft Academic Search

Two sol-gel fabrication processes were investigated to make silica spheres containing Ag nanoparticles: (1) a modified St鐽er method for silica spheres below 1 痠 size, and (2) a SiO2-film formation method on spheres of 3;7 痠 size. The spheres were designed to incorporate silver nanoparticles of high ?(3) in a spherical optical cavity structure for the resonance effect. For the

S. Shibata; K. Aoki; T. Yano; M. Yamane

1998-01-01

155

Exciton energy transfer between nanoparticles and nanowires  

Microsoft Academic Search

In this paper, we study the processes of exciton transfer in coupled nanoparticles and nanowires, and obtain convenient equations and numerical results for energy-transfer rates. For large distances, the energy-transfer rates are proportional to 1\\/d5 , where d is the nanoparticle-nanowire distance. Our models incorporate both semiconductor and metal material systems. In this paper, we show that excitonic energy generated

Pedro L. Hern嫕dez-Mart璯ez; Alexander O. Govorov

2008-01-01

156

Polymeric Nanoparticles for siRNA Delivery and Gene Silencing  

Microsoft Academic Search

Gene silencing using small interfering RNA (siRNA) has several potential therapeutic applications. In the present study, we investigated nanoparticles formulated using the biodegradable polymer, poly (D,L-lactide-co-glycolide) (PLGA) for siRNA delivery. A cationic polymer, polyethylenimine (PEI), was incorporated in the PLGA matrix to improve siRNA encapsulation in PLGA nanoparticles. PLGA-PEI nanoparticles were formulated using double emulsion-solvent evaporation technique and characterized for

Yogesh Patil; Jayanth Panyam

2009-01-01

157

Precision Nanoparticles  

SciTech Connect

A revolutionary technology that efficiently produces nanoparticles in uniform and prescribed sizes (1-100 nanometers) using supercritical fluids. INL researcher Robert Fox was joined by Idaho State University researchers Rene Rodriquez and Joshua Pak in d

John Hemminger

2009-07-21

158

Precision Nanoparticles  

ScienceCinema

A revolutionary technology that efficiently produces nanoparticles in uniform and prescribed sizes (1-100 nanometers) using supercritical fluids. INL researcher Robert Fox was joined by Idaho State University researchers Rene Rodriquez and Joshua Pak in d

John Hemminger

2010-01-08

159

Cancer detection using nanoparticle-based sensors.  

PubMed

This tutorial review surveys the latest achievements in the use of nanoparticles to detect cancer biomarkers and cancer cells with a focus on optical and electrochemical techniques. Nanoparticle based cancer diagnostics are becoming an increasingly relevant alternative to traditional techniques. Although some drawbacks exist in relation to the obtained sensitivity the use of nanoparticle-based sensors in biomarker detection or cancer cell detection offers some advantages in comparison to conventional methods. The developed techniques can be interesting and relevant for their use in point-of-care of cancer diagnostics. The methods can be of low cost and in addition easy to be incorporated into user-friendly sensing platforms. PMID:21796315

Perf憴ou, Ma螔le; Turner, Anthony; Merko蓾, Arben

2012-04-01

160

Zinc Incorporation Into Hydroxylapatite  

SciTech Connect

By theoretical modeling and X-ray absorption spectroscopy, the local coordination structure of Zn incorporated into hydroxylapatite was examined. Density function theory (DFT) calculations show that Zn favors the Ca2 site over the Ca1 site, and favors tetrahedral coordination. X-ray absorption near edge structure (XANES) spectroscopy results suggest one dominant coordination environment for the incorporated Zn, and no evidence was observed for other Zn-containing phases. Extended X-ray absorption fine structure (EXAFS) fitting of the synthetic samples confirms that Zn occurs in tetrahedral coordination, with two P shells at 2.85-3.07 {angstrom}, and two higher Ca shells at 3.71-4.02 {angstrom}. These fit results are consistent with the most favored DFT model for Zn substitution in the Ca2 site.

Tang, Y.; Chappell, H; Dove, M; Reeder, R; Lee, Y

2009-01-01

161

Separation of patuletin-3-O-glucoside, astragalin, quercetin, kaempferol and isorhamnetin from Flaveria bidentis (L.) Kuntze by elution-pump-out high-performance counter-current chromatography.  

PubMed

Flaveria bidentis (L.) Kuntze is an annual alien weed of Flaveria Juss. (Asteraceae) in China. Bioactive compounds, mainly flavonol glycosides and flavones from F. bidentis (L.) Kuntze, have been studied in order to utilize this invasive weed, Analytical high-performance counter-current chromatography (HPCCC) was successfully used to separate patuletin-3-O-glucoside, a mixture of hyperoside (quercetin-3-O-galactoside) and 6-methoxykaempferol-3-O-galactoside, astragalin, quercetin, kaempferol and isorhamnetin using two runs with different solvent system. Ethyl acetate-methanol-water (10:1:10, v/v) was selected by analytical HPCCC as the optimum phase system for the separation of patuletin-3-O-glucoside, a mixture of hyperoside and 6-methoxykaempferol-3-O-galactoside, and astragalin. A Dichloromethane-methanol-water (5:3:2, v/v) was used for the separation of quercetin, kaempferol and isorhamnetin. The separation was then scaled up: the crude extract (ca 1.5 g) was separated by preparative HPCCC, yielding 12 mg of patuletin-3-O-glucoside at a purity of 98.3%, yielding 9 mg of a mixture of hyperoside and 6-methoxykaempferol-3-O-galactoside constituting over 98% of the fraction, and 16 mg of astragalin (kaempferol-3-O-glucoside) at a purity of over 99%. The pump-out peaks are isorhanetin (98% purity), kaemferol (93% purity) and quercitin (99% purity). The chemical structure of patuletin-3-O-glucoside and astragalin were confirmed by MS and 違, 像C NMR. PMID:21329934

Wei, Yun; Xie, Qianqian; Fisher, Derek; Sutherland, Ian A

2011-09-01

162

Gold Nanoparticle Labels Amplify Ellipsometric Signals  

NASA Technical Reports Server (NTRS)

The ellipsometric method reported in the immediately preceding article was developed in conjunction with a method of using gold nanoparticles as labels on biomolecules that one seeks to detect. The purpose of the labeling is to exploit the optical properties of the gold nanoparticles in order to amplify the measurable ellipsometric effects and thereby to enable ultrasensitive detection of the labeled biomolecules without need to develop more-complex ellipsometric instrumentation. The colorimetric, polarization, light-scattering, and other optical properties of nanoparticles depend on their sizes and shapes. In the present method, these size-and-shape-dependent properties are used to magnify the polarization of scattered light and the diattenuation and retardance of signals derived from ellipsometry. The size-and-shape-dependent optical properties of the nanoparticles make it possible to interrogate the nanoparticles by use of light of various wavelengths, as appropriate, to optimally detect particles of a specific type at high sensitivity. Hence, by incorporating gold nanoparticles bound to biomolecules as primary or secondary labels, the performance of ellipsometry as a means of detecting the biomolecules can be improved. The use of gold nanoparticles as labels in ellipsometry has been found to afford sensitivity that equals or exceeds the sensitivity achieved by use of fluorescence-based methods. Potential applications for ellipsometric detection of gold nanoparticle-labeled biomolecules include monitoring molecules of interest in biological samples, in-vitro diagnostics, process monitoring, general environmental monitoring, and detection of biohazards.

Venkatasubbarao, Srivatsa

2008-01-01

163

Poly( d, l-lactide-co-glycolide)\\/montmorillonite nanoparticles for oral delivery of anticancer drugs  

Microsoft Academic Search

This research developed a novel bioadhesive drug delivery system, poly(d,l-lactide-co-glycolide)\\/montmorillonite (PLGA\\/MMT) nanoparticles, for oral delivery of paclitaxel. Paclitaxel-loaded PLGA\\/MMT nanoparticles were prepared by the emulsion\\/solvent evaporation method. MMT was incorporated in the formulation as a matrix material component, which also plays the role of a co-emulsifier in the nanoparticle preparation process. Paclitaxel-loaded PLGA\\/MMT nanoparticles were found to be of spherical

Yuancai Dong; Si-Shen Feng

2005-01-01

164

Metal-Insulating-Semi-Incorporation of Silicon Nanoparticles into  

E-print Network

Cells Introduction Photovoltaic Cells Conclusions Acknowledgements PIN junctions 繚 P and N type doped photovoltaic cells diode-like behavior and ideally allow for unidirectional current flow. 繚 Two way current and other characteristics such as the Open Circuit Voltage, Short Circuit Current, and Fill Factor. 1Jann

165

Incorporation of silica into baroplastic core-shell nanoparticles  

E-print Network

Core-shell baroplastics are nanophase materials that exhibit pressure-induced flow at low temperatures and high pressures. Core-shell baroplastics used in this work are comprised of a low Tg poly(butyl acrylate) (PBA) core ...

Hewlett, Sheldon A

2006-01-01

166

Preparation of drug nanoparticles by emulsion evaporation method  

NASA Astrophysics Data System (ADS)

Polymeric drug nanoparticles were prepared by emulsion solvent evaporation method. In this study, prepared the polymeric drug nanoparticles consist of ketoprofen and Eudragit E 100. The morphology structure was investigated by scanning electron microscopy (SEM). The interactions between the drug and polymer were investigated by Fourier transform infrared spectroscopy (FTIR). The size distribution was measured by means of Dynamic Light Scattering. The nanoparticles have an average size of about 150 nm. The incorporation ability of drugs in the polymeric nanoparticles depended on the integration between polymer and drug as well as the glass transition temperature of the polymer.

Hoa, Le Thi Mai; Chi, Nguyen Tai; Triet, Nguyen Minh; Thanh Nhan, Le Ngoc; Mau Chien, Dang

2009-09-01

167

PLGA nanoparticles prepared by nanoprecipitation: drug loading and release studies of a water soluble drug  

Microsoft Academic Search

The nanoprecipitation technique for preparation of nanoparticles suffers the drawback of poor incorporation of water soluble drugs. The aim of this study was therefore to assess various formulation parameters to enhance the incorporation of a water soluble drug (procaine hydrochloride) into poly(dl-lactide-co-glycolide) (PLGA) nanoparticles prepared by this technique. Approaches investigated for drug incorporation efficiency enhancement included the influence of aqueous

Thirumala Govender; Snjezana Stolnik; Martin C. Garnett; Lisbeth Illum; Stanley S. Davis

1999-01-01

168

Recovery and redispersion of gold nanoparticles using the self-assembly of a pH sensitive zwitterionic amphiphile.  

PubMed

The pH-responsive self-assembly of zwitterionic amphiphile C16CA was expanded to the recovery of gold (Au) nanoparticles for environmentally friendly chemistry applications. Multilayered lamellae at pH ? 4 were successfully incorporated into nanoparticles by dispersion. Redispersion of nanoparticles was achieved under basic conditions by the transition of self-assembly. PMID:25219607

Morita-Imura, Clara; Imura, Yoshiro; Kawai, Takeshi; Shindo, Hitoshi

2014-09-30

169

In vitro acoustic molecular imaging of tissue factor expressed by smooth muscle cells with stable liquid perfluorocarbon nanoparticle contrast agents  

Microsoft Academic Search

Liquid perfluorocarbon nanoparticle contrast agents can be used to target specific tissue types through incorporation of appropriate ligands into the nanoparticles' outer lipid monolayer. In this study we sought to characterize the specificity of targeting of perfluorooctyl bromide (PFOB) nanoparticles to tissue factor, a transmembrane glycoprotein expressed by smooth muscle cells as part of inflammatory response after vessel injury (e.g.,

Jon N. Marsh; Kathryn C. Crowder; Michael S. Hughes; Michael J. Scott; Elizabeth K. Lacy; Gregory M. Lanza; Samuel A. Wickline

2004-01-01

170

Towards the Rational Design of Nanoparticle Catalysts  

NASA Astrophysics Data System (ADS)

This research is focused on development of routes towards the rational design of nanoparticle catalysts. Primarily, it is focused on two main projects; (1) the use of imidazolium-based ionic liquids (ILs) as greener media for the design of quasi-homogeneous nanoparticle catalysts and (2) the rational design of heterogeneous-supported nanoparticle catalysts from structured nanoparticle precursors. Each project has different studies associated with the main objective of the design of nanoparticle catalysts. In the first project, imidazolium-based ionic liquids have been used for the synthesis of nanoparticle catalysts. In particular, studies on recyclability, reuse, mode-of-stability, and long-term stability of these ionic-liquid supported nanoparticle catalysts have been done; all of which are important factors in determining the overall "greenness" of such synthetic routes. Three papers have been published/submitted for this project. In the first publication, highly stable polymer-stabilized Au, Pd and bimetallic Au-Pd nanoparticle catalysts have been synthesized in imidazolium-based 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF6) ionic liquid (Journal of Molecular Catalysis A: Chemical, 2008, 286, 114). The resulting nanoparticles were found to be effective and selective quasi-homogeneous catalysts towards a wide-range of hydrogenation reactions and the catalyst solution was reused for further catalytic reactions with minimal loss in activity. The synthesis of very pure and clean ILs has allowed a platform to study the effects of impurities in the imidazolium ILs on nanoparticle stability. In a later study, a new mode of stabilization was postulated where the presence of low amounts of 1-methylimidazole has substantial effects on the resulting stability of Au and Pd-Au nanoparticles in these ILs (Chemical Communications, 2009, 812). In further continuation of this study, a comparative study involving four stabilization protocols for nanoparticle stabilization in BMIMPF6 IL is described, and have shown that nanoparticle stability and catalytic activity of nanoparticles is dependent on the overall stability of the nanoparticles towards aggregation (manuscript submitted). The second major project is focused on synthesizing structurally well-defined supported catalysts by incorporating the nanoparticle precursors (both alloy and core shell) into oxide frameworks (TiO2 and Al2O 3), and examining their structure-property relationships and catalytic activity. a full article has been published on this project (Journal of Physical Chemistry C, 2009, 113, 12719) in which a route to rationally design supported catalysts from structured nanoparticle precursors with precise control over size, composition, and internal structure of the nanoparticles has been shown. In a continuation of this methodology for the synthesis of heterogeneous catalysts, efforts were carried out to apply the same methodology in imidazolium-based ILs as a one-pot media for the synthesis of supported-nanoparticle heterogeneous catalysts via the trapping of pre-synthesized nanoparticles into porous inorganic oxide materials. Nanoparticle catalysts in highly porous titania supports were synthesized using this methodology (manuscript to be submitted).

Dash, Priyabrat

171

Magnetic nanoparticles  

Microsoft Academic Search

Intrinsic properties of magnetic nanoparticles are reviewed, with special emphasis on the effects of finite size on zero-temperature spin ordering, magnetic excitations, and relaxation. Effects on zero-temperature spin ordering include moment enhancement due to band narrowing in 3d transition metal particles, surface spin disorder in ferrite particles, and multi-sublattice states in antiferromagnetic oxide particles. Magnetic excitations include discretized spin wave

R. H Kodama

1999-01-01

172

Incorporation of pyrene in polypyrrole/polystyrene magnetic beads  

NASA Astrophysics Data System (ADS)

Pyrene, a fluorescent dye, was incorporated into polystyrene particles coated with polypyrrole. The incorporation was achieved by treating the polypyrrole/polystyrene (PPy/PS) beads in a tetrahydrofuran (THF) solution of the pyrene fluorophore followed by rinsing with methanol. The polystyrene cores of the beads swell in THF, allowing penetration of pyrene molecules into the polystyrene structure. The addition of methanol causes contraction of the swollen polystyrene, which encapsulates the dye molecules inside the beads. It is shown that the polypyrrole coating is permeable with respect to both the dye and the solvent, allowing the transport of molecules between the polystyrene cores and the contacting solution. The polypyrrole adlayer can be used as a matrix for the incorporation of magnetic nanoparticles. Embedded particles provide magnetic functionality to the PPy/PS beads. It is demonstrated that the pyrene-loaded beads can be manipulated with an external magnetic field.

G?owala, Paulina; Budniak, Adam; Krug, Pamela; Wysocka, Barbara; Berbe?, Sylwia; Dec, Robert; Do??ga, Izabela; Kacprzak, Kamil; Wojciechowski, Jaros?aw; Kawa?ko, Jakub; K?pka, Pawe?; K?pi?ska, Daria; Kijewska, Krystyna; Mazur, Maciej

2014-10-01

173

PEM Electrolyzer Incorporating an Advanced  

E-print Network

PEM Electrolyzer Incorporating an Advanced Low Cost Membrane Monjid Hamdan Giner Electrochemical of chemically-etched DSM supports for further cost reduction. 100% (Mar-09) 100% (Mar-09) 100% (Dec-10 ionomer incorporated in an engineering plastic support High-strength High-efficiency No x-y dimensional

174

Pure drug nanoparticles in tablets: what are the dissolution limitations?  

Microsoft Academic Search

There has been increasing interests for drug companies to incorporate drug nanoparticles into their existing formulations.\\u000a However, technical knowledge in this area is still in its infancy and more study needs to be done to stimulate growth in this\\u000a fledging field. There is a need to scrutinize the performance of pure drug nanoparticles in tablets, particularly relating\\u000a formulation variables to

Desmond Heng; Keiko Ogawa; David J. Cutler; Hak-Kim Chan; Judy A. Raper; Lin Ye; Jimmy Yun

2010-01-01

175

Evidence for avoidance of Ag nanoparticles by earthworms ( Eisenia fetida )  

Microsoft Academic Search

Silver nanoparticles have been incorporated into a wide variety of consumer products, ideally acting as antimicrobial agents.\\u000a Silver exposure has long been known to cause toxic effects to a wide variety of organisms, making large scale production of\\u000a silver nanoparticles a potential hazard to environmental systems. Here we describe the first evidence that an organism may\\u000a be able to sense

W. A. Shoults-Wilson; Oksana I. Zhurbich; David H. McNear; Olga V. Tsyusko; Paul M. Bertsch; Jason M. Unrine

2011-01-01

176

Investigation of antibacterial activity of cotton fabric incorporating nano silver colloid  

Microsoft Academic Search

In this work, silver nanoparticles were prepared by polyol process with microwave heating and incorporated on cotton fabric surfaces. The antibacterial performance of the antibacterial cotton fabric was tested for different concentration of nano-sized silver colloid, contact time germs, and washing times. It was found that antibacterial activity increased with the increasing concentration of nano-sized silver colloid. The antibacterial fabric

Ngo Vo Ke Thanh; Nguyen Thi Phuong Phong

2009-01-01

177

Evaluation of the physical stability of SLN and NLC before and after incorporation into hydrogel formulations  

Microsoft Academic Search

Aqueous dispersions of lipid nanoparticles are being investigated as drug delivery systems for different therapeutic purposes. One of their interesting features is the possibility of topical use, for which these systems have to be incorporated into commonly used dermal carriers, such as creams or hydrogels, in order to have a proper semisolid consistency. For the present investigation four different gel-forming

E. B Souto; S. A Wissing; C. M Barbosa; R. H Mller

2004-01-01

178

Incorporation of nanovoids into metallic gratings for broadband plasmonic organic solar  

E-print Network

in photocurrent enhancement by plasmonic nanoparticle arrays located on the front or on the rear of solar cellsIncorporation of nanovoids into metallic gratings for broadband plasmonic organic solar cells investigation and optimization of a newly proposed plasmonic organic solar cell geometry based

Park, Namkyoo

179

Critical enhancements of MRI contrast and hyperthermic effects by dopant-controlled magnetic nanoparticles.  

PubMed

Doped up: The incorporation of Zn(2+) dopants in tetrahedral sites leads to the successful magnetism tuning of spinel metal ferrite nanoparticles (see picture). (Zn(0.4)Mn(0.6))Fe(2)O(4) nanoparticles exhibit the highest magnetization value among the metal ferrite nanoparticles. Such high magnetism results in the largest MRI contrast effects (r2=860 mm(-1) s(-1)) reported to date and also huge hyperthermic effects. PMID:19137514

Jang, Jung-tak; Nah, Hyunsoo; Lee, Jae-Hyun; Moon, Seung Ho; Kim, Min Gyu; Cheon, Jinwoo

2009-01-01

180

Preparation and evaluation of lectin-conjugated PLGA nanoparticles for oral delivery of thymopentin  

Microsoft Academic Search

The purpose of this study was to design and evaluate lectin-conjugated PLGA nanoparticles for oral delivery of thymopentin. Thymopentin loaded PLGA nanoparticles (TP5NPs) were prepared by a double emulsion-solvent evaporation technique. Novel WGAPLGA conjugates were synthesized by coupling the amino groups of wheat germ agglutinin (WGA) to the carbodiimide-activated carboxylic groups of PLGA, and were incorporated into nanoparticles preparation to

YaShu Yin; DaWei Chen; MingXi Qiao; Zhe Lu; HaiYang Hu

2006-01-01

181

Nanoparticle-polymer composite membranes: Synthesis, characterization, and environmental applications  

NASA Astrophysics Data System (ADS)

Advances in nanotechnology and materials science offer new possibilities for the development of novel water treatment technologies A salient example is the emergence of a new generation of nanostructured membranes with improved separation properties and, in some cases, multifunctional capabilities. The present work explores different aspects of the formation of nanoparticle-enabled membranes, focusing on the dependence between synthetic methods, nanoparticle properties, and the performance of the obtained membranes. The effects of nanoparticle loading, size and morphology, and methods of nanoparticle incorporation on the functional properties of the resulting nanocomposite membranes are studied. Additionally, empirical predictors of membrane performance for the rational design of nanocomposite membranes and novel strategies for the manufacture of membrane-based sensors and biofouling resistant membrane spacers are presented. The first chapter of the dissertation provides an overview of the theory of phase inversion in polymer blends -- one of the main methods for the fabrication of ultrafiltration membranes. The second chapter describes the study of the effect of shape and loading of carbon nanoparticle fillers on the hydraulic properties of nanocomposite membranes. In the third chapter, the effects of casting mixture composition and nanoparticle incorporation route on the morphological structure and separation performance of nanocomposite membranes are described and the potential use of these nanocomposites for the mitigation of membrane biofouling is discussed. Finally, in the last chapter, a method for the synthesis of a nanoparticle-enabled, membrane-based sensor for water quality control is presented.

Taurozzi, Julian S.

182

Defect-free nanostructured alumina coating doped with noble metal nanoparticles  

Microsoft Academic Search

Nanostructured alumina coatings loaded with platinum or gold nanoparticles were prepared by two different methods. In the first method the alumina coatings were prepared in the presence of metal ions, which were reduced using UV irradiation once the film was deposited. In the second method, polyvinylpyrrolidone-stabilized nanoparticles were first synthesized and then incorporated in the coating. The texturation of the

Miroslava Malenovska; Marie-Alexandra Neouze; Ulrich Schubert; Veronique Monnier; Emmanuel Scolan; Raphael Pugin

2009-01-01

183

Preparation, Characterization, and Release Study of Tacrolimus-Loaded Liquid Crystalline Nanoparticles  

Microsoft Academic Search

Use of liquid crystalline nanoparticles is a novel approach in the field of controlled drug delivery. Tacrolimus, being a highly lipophilic drug, is easily incorporated in the hydrophobic core of these nanoparticles which are prepared using monoolein, distilled water and varying ratios of poloxamer 407. Characterization including Transmission Electron Microscopy (TEM) image, particle size and entrapment efficiency analysis suggested the

Raj Kumar Thapa; Rengarajan Baskaran; Thiagarajan Madheswaran; Jong Oh Kim; Chul Soon Yong; Bong Kyu Yoo

2012-01-01

184

Antibacterial Effect of Silver Nanoparticles Produced by Fungal Process on Textile Fabrics and Their Effluent Treatment  

Microsoft Academic Search

Microorganisms play an important role in toxic metal remediation through reduction of metal ions. Studies demonstrated that silver ions may be reduced extracellularly using Fusarium oxysporum to generate stable gold or silver nanoparticles in water. These particles can be incorporated in several kinds of materials such as cloths. These cloths with silver nanoparticles are sterile and can be useful in

Nelson Dur嫕; Priscyla D. Marcato; Gabriel I. H. De Souza; Oswaldo L. Alves; Elisa Esposito

2007-01-01

185

Erbium-doped nanoparticles in silica-based optical Wilfried Blanc*, Valrie Mauroy, Bernard  

E-print Network

on the incorporation of erbium ions in amorphous dielectric nanoparticles, grown in-situ in fiber preforms. By adding to modify some spectroscopic properties of rare-earth ions in silica- based fibers based of nanometric erbium-doped dielectric nanoparticles within the core of silica fibers. We present

Boyer, Edmond

186

Enhancement of ultrasound reflectivity depends on the specific perfluorocarbons utilized to formulate nanoparticle emulsion contrast agents  

Microsoft Academic Search

A nongaseous, ligand-targeted perfluorocarbon nanoparticle emulsion has been developed which can acoustically enhance the presence of molecular epitopes on tissue surfaces. We demonstrate the impact of incorporating perfluorocarbons with specific phase velocities into the emulsions on the acoustic reflectivity of plasma clots targeted using these nanoparticles. Porcine plasma clots were targeted in vitro with specific perfluorocarbon emulsions using anti-fibrin antibody

Jon N. Marsh; Christopher S. Hall; Michael J. Scott; Ralph J. Fuhrhop; Patrick J. Gaffney; Samuel A. Wickline; Gregory M. Lanza

2000-01-01

187

Solid lipid nanoparticles (SLN) for controlled drug delivery a review of the state of the art  

Microsoft Academic Search

Solid lipid nanoparticles (SLN) introduced in 1991 represent an alternative carrier system to traditional colloidal carriers, such as emulsions, liposomes and polymeric micro- and nanoparticles. SLN combine advantages of the traditional systems but avoid some of their major disadvantages. This paper reviews the present state of the art regarding production techniques for SLN, drug incorporation, loading capacity and drug release,

Rainer H. Mller; Karsten M輐er; Sven Gohla

2000-01-01

188

Pefloxacine mesilate- and ofloxacin-loaded polyethylcyanoacrylate nanoparticles: characterization of the colloidal drug carrier formulation.  

PubMed

The entrapment of fluoroquinolones, perfloxacine mesilate (PFX) and ofloxacin (OFX), in polyalkylcyanoacrylate (PECA) nanoparticles could offer some advantages for their biological application; for examples, increasing their bioavailability, controlling the drug time-release in blood, and reducing the formation of bacterial resistance. To load these two drugs in PECA polymeric bulk, the incorporation or adsorption method was performed. These two methods were capable of influencing nanoparticle size, molecular weight, release profile, and drug-polymer association. The incorporation method, particularly for the OFX system, achieved PECA nanoparticle suspensions with a mean size value three times higher than that obtained in the absence of the drug. In contrast, negligible changes were observed for PFX systems. This preparation process also influenced the nanoparticle storage stability. The molecular weight values of the various nanoparticle preparations were also influenced; that is, the PFX-loaded systems showed an enhancement in the average molecular weight values, whereas a reduction was observed for OFX-loaded systems. The adsorption method showed no particular difference in particle size, molecular weight, and storage stability compared with nanoparticles prepared without the drugs. The nanoparticle loading capacity was higher for the colloidal systems obtained following the incorporation preparation procedure. The release of drug from the nanoparticles was biphasic for both preparation processes. The fluoro-quinolone-loaded nanoparticles showed an enhancement of the antimicrobial activity against standard bacteria strains from 2- to 50-fold compared with the free drugs. PMID:7562444

Fresta, M; Puglisi, G; Giammona, G; Cavallaro, G; Micali, N; Furneri, P M

1995-07-01

189

Incorporate GPS into Geologic Mapping  

NSDL National Science Digital Library

William Montgomery, New Jersey City University Summary This activity is an easy and fun way to incorporate GPS into a Field Methods course. It facilitates "asynchronous" learning by enabling urban, ...

Montgomery, William

190

Stabilisation effects of superparamagnetic nanoparticles on clustering in nanocomposite microparticles and on magnetic behaviour  

NASA Astrophysics Data System (ADS)

Superparamagnetic nanoparticles of magnetite were coprecipitated from iron salts, dispersed with nitric acid and stabilised either by lactic acid (LA) or by a polycarboxylate-ether polymer (MELPERS4343, MP). The differently stabilised nanoparticles were incorporated into a silica matrix to form nanocomposite microparticles. The silica matrix was prepared either from tetraethylorthosilicate (TEOS) or from an aqueous sodium silicate (water glass) solution. Stabilisation of nanoparticles had a crucial influence on microparticle texture and nanoparticle distribution in the silica matrix. Magnetic measurements in combination with transmission electron microscopy (TEM) investigations suggest a uniform magnetic interaction of nanoparticles in case of LA stabilisation and magnetically interacting nanoparticle clusters of different sizes in case of MP stabilisation. Splitting of blocking temperature (TB) and irreversible temperature (Tir) in zero field cooled (ZFC) and field cooled (FC) measurements is discussed in terms of nanoparticle clustering.

Mandel, K.; Hutter, F.; Gellermann, C.; Sextl, G.

2013-04-01

191

Delineating the pathways for the site-directed synthesis of individual nanoparticles on surfaces  

PubMed Central

Although nanoparticles with exquisite properties have been synthesized for a variety of applications, their incorporation into functional devices is challenging owing to the difficulty in positioning them at specified sites on surfaces. In contrast with the conventional synthesis-then-assembly paradigm, scanning probe block copolymer lithography can pattern precursor materials embedded in a polymer matrix and synthesize desired nanoparticles on site, offering great promise for incorporating nanoparticles into devices. This technique, however, is extremely limited from a materials standpoint. To develop a materials-general method for synthesizing nanoparticles on surfaces for broader applications, a mechanistic understanding of polymer-mediated nanoparticle formation is crucial. Here, we design a four-step synthetic process that enables independent study of the two most critical steps for synthesizing single nanoparticles on surfaces: phase separation of precursors and particle formation. Using this process, we elucidate the importance of the polymer matrix in the diffusion of metal precursors to form a single nanoparticle and the three pathways that the precursors undergo to form nanoparticles. Based on this mechanistic understanding, the synthetic process is generalized to create metal (Au, Ag, Pt, and Pd), metal oxide (Fe2O3, Co2O3, NiO, and CuO), and alloy (AuAg) nanoparticles. This mechanistic understanding and resulting process represent a major advance in scanning probe lithography as a tool to generate patterns of tailored nanoparticles for integration with solid-state devices. PMID:23277538

Liu, Guoliang; Eichelsdoerfer, Daniel J.; Rasin, Boris; Zhou, Yu; Brown, Keith A.; Liao, Xing; Mirkin, Chad A.

2013-01-01

192

Nanoparticles by Laser Ablation  

Microsoft Academic Search

This review concerns nanoparticles collected in the form of nanopowder or a colloidal solution by laser ablating a solid target that lies in a gaseous or a liquid environment. The paper discusses the advantages of the method as compared with other methods for nanoparticle synthesis, outlines the factors on which the properties of the produced nanoparticles depend, explains the mechanisms

N. G. Semaltianos

2010-01-01

193

Modified natural nanoparticles as contrast agents for medical imaging  

PubMed Central

The development of novel and effective contrast agents is one of the drivers of the ongoing improvement in medical imaging. Many of the new agents reported are nanoparticle-based. There are a variety of natural nanoparticles known, e.g. lipoproteins, viruses or ferritin. Natural nanoparticles have advantages as delivery platforms such as biodegradability. In addition, our understanding of natural nanoparticles is quite advanced, allowing their adaptation as contrast agents. They can be labeled with small molecules or ions such as Gd3+ to act as contrast agents for magnetic resonance imaging, 18F to act as positron emission tomography contrast agents or fluorophores to act as contrast agents for fluorescence techniques. Additionally, inorganic nanoparticles such as iron oxide, gold nanoparticles or quantum dots can be incorporated to add further contrast functionality. Furthermore, these natural nanoparticle contrast agents can be rerouted from their natural targets via the attachment of targeting molecules. In this review, we discuss the various modified natural nanoparticles that have been exploited as contrast agents. PMID:19900496

Cormode, David P.; Jarzyna, Peter A.; Mulder, Willem J. M.; Fayad, Zahi A.

2009-01-01

194

Synthesis and Characterization of Gold-Titanium Dioxide Nanoparticles  

NASA Astrophysics Data System (ADS)

Nanoparticles are of recent scientific interest due to their unique size-dependent optical, electrical, and catalytic properties. Gold nanoparticles specifically, have many potential applications, especially in optoelectronic devices due to their optical properties and plasmon resonance. The specific goals of this research are to synthesize Au/TiO2 core-shell nanoparticles for their use in improving the overall efficiency of P3HT/PCBM polymer solar cells previously prepared in our lab. The standard sodium citrate reduction method was used to synthesize gold nanoparticles with an average diameter of 15 nm. Through changing the concentration of sodium citrate in solution we were able to tune the size of the nanoparticles, and therefore change their light-absorbing properties. The goals of this research are to cap the gold nanoparticles with TiO2 through a sol-gel method. Characterization of the Au/TiO2 particles will be performed using high resolution tunneling electron microscopy to determine the size of the nanoparticles and the thickness of the TiO2 shell. In addition, ultraviolet-visual spectroscopy was used to determine the absorption of the particles, and dynamic light scattering was used to confirm the size distribution of the particles. The incorporation of Au/TiO2 nanoparticles in P3HT/PCBM devices will be discussed.

Cramer, Hailey; Shah, Ismat

2013-03-01

195

Nanoparticles for transcutaneous vaccination.  

PubMed

The living epidermis and dermis are rich in antigen presenting cells (APCs). Their activation can elicit a strong humoral and cellular immune response as well as mucosal immunity. Therefore, the skin is a very attractive site for vaccination, and an intradermal application of antigen may be much more effective than a subcutaneous or intramuscular injection. However, the stratum corneum (SC) is a most effective barrier against the invasion of topically applied vaccines. Products which have reached the stage of clinical testing, avoid this problem by injecting the nano-vaccine intradermally or by employing a barrier disrupting method and applying the vaccine to a relatively large skin area. Needle-free vaccination is desirable from a number of aspects: ease of application, improved patient acceptance and less risk of infection among them. Nanocarriers can be designed in a way that they can overcome the SC. Also incorporation into nanocarriers protects instable antigen from degradation, improves uptake and processing by APCs, and facilitates endosomal escape and nuclear delivery of DNA vaccines. In addition, sustained release systems may build a depot in the tissue gradually releasing antigen which may avoid booster doses. Therefore, nanoformulations of vaccines for transcutaneous immunization are currently a very dynamic field of research. Among the huge variety of nanocarrier systems that are investigated hopes lie on ultra-flexible liposomes, superfine rigid nanoparticles and nanocarriers, which are taken up by hair follicles. The potential and pitfalls associated with these three classes of carriers will be discussed. PMID:21854553

Hansen, Steffi; Lehr, Claus-Michael

2012-03-01

196

Nanoparticles for transcutaneous vaccination  

PubMed Central

Summary The living epidermis and dermis are rich in antigen presenting cells (APCs). Their activation can elicit a strong humoral and cellular immune response as well as mucosal immunity. Therefore, the skin is a very attractive site for vaccination, and an intradermal application of antigen may be much more effective than a subcutaneous or intramuscular injection. However, the stratum corneum (SC) is a most effective barrier against the invasion of topically applied vaccines. Products which have reached the stage of clinical testing, avoid this problem by injecting the nano?vaccine intradermally or by employing a barrier disrupting method and applying the vaccine to a relatively large skin area. Needle?free vaccination is desirable from a number of aspects: ease of application, improved patient acceptance and less risk of infection among them. Nanocarriers can be designed in a way that they can overcome the SC. Also incorporation into nanocarriers protects instable antigen from degradation, improves uptake and processing by APCs, and facilitates endosomal escape and nuclear delivery of DNA vaccines. In addition, sustained release systems may build a depot in the tissue gradually releasing antigen which may avoid booster doses. Therefore, nanoformulations of vaccines for transcutaneous immunization are currently a very dynamic field of research. Among the huge variety of nanocarrier systems that are investigated hopes lie on ultra?flexible liposomes, superfine rigid nanoparticles and nanocarriers, which are taken up by hair follicles. The potential and pitfalls associated with these three classes of carriers will be discussed. PMID:21854553

Hansen, Steffi; Lehr, Claus-Michael

2012-01-01

197

Finite Size Effects on the Real-Space Pair Distribution Function of Nanoparticles  

SciTech Connect

The pair distribution function (PDF) method is a powerful approach for the analysis of the structure of nanoparticles. An important approximation used in nanoparticle PDF simulations is the incorporation of a form factor describing nanoparticle size and shape. The precise effect of the form factor on the PDF is determined by both particle shape and structure if these characteristics are both anisotropic and correlated. The correct incorporation of finite size effects is important for distinguishing and quantifying the structural consequences of small particle size in nanomaterials.

Gilbert, Benjamin

2008-10-01

198

Assessing Nanoparticle Toxicity  

NASA Astrophysics Data System (ADS)

Nanoparticle toxicology, an emergent field, works toward establishing the hazard of nanoparticles, and therefore their potential risk, in light of the increased use and likelihood of exposure. Analytical chemists can provide an essential tool kit for the advancement of this field by exploiting expertise in sample complexity and preparation as well as method and technology development. Herein, we discuss experimental considerations for performing in vitro nanoparticle toxicity studies, with a focus on nanoparticle characterization, relevant model cell systems, and toxicity assay choices. Additionally, we present three case studies (of silver, titanium dioxide, and carbon nanotube toxicity) to highlight the important toxicological considerations of these commonly used nanoparticles.

Love, Sara A.; Maurer-Jones, Melissa A.; Thompson, John W.; Lin, Yu-Shen; Haynes, Christy L.

2012-07-01

199

Cell tracking using nanoparticles.  

PubMed

Tracking cells in regenerative medicine is becoming increasingly important for basic cell therapy science, for cell delivery optimization and for accurate biodistribution studies. This report describes nanoparticles that utilize stable-isotope metal labels for multiple detection technologies in preclinical studies. Cells labeled with nanoparticles can be imaged by electron microscopy, fluorescence, and magnetic resonance. The nanoparticle-labeled cells can be quantified by neutron activation, thereby allowing, with the use of standard curves, the determination of the number of labeled cells in tissue samples from in vivo sources. This report describes the characteristics of these nanoparticles and methods for using these nanoparticles to label and track cells. PMID:20559922

Vaccaro, Dennis E; Yang, Meiheng; Weinberg, James S; Reinhardt, Christopher P; Groman, Ernest V

2008-09-01

200

Incorporating externalities in conservation programs  

SciTech Connect

As water utilities incorporate integrated resource planning in their management processes, it is necessary to incorporate the concept of externalities. This is particularly important as methods evolve of evaluating the costs and benefits of water conservation programs. The purpose of this article is to provide an introduction to the issues surrounding externalities, including their definition, methods of internalizing externalities, and a survey of ways to estimate costs and benefits of externalities. Although most discussions of externalities emphasize negative effects on the environment, this article will illustrate both positive and negative externalities associated with practicing water conservation.

Jordan, J.L. [Georgia Experiment Station, Griffin, GA (United States). Dept. of Agricultural and Applied Economics

1995-06-01

201

Investigation of antibacterial activity of cotton fabric incorporating nano silver colloid  

NASA Astrophysics Data System (ADS)

In this work, silver nanoparticles were prepared by polyol process with microwave heating and incorporated on cotton fabric surfaces. The antibacterial performance of the antibacterial cotton fabric was tested for different concentration of nano-sized silver colloid, contact time germs, and washing times. It was found that antibacterial activity increased with the increasing concentration of nano-sized silver colloid. The antibacterial fabric with 758 mg/kg of silver nanoparticles on surface cotton was highly effective in killing test bacteria and had excellent water resisting property.

Thanh, Ngo Vo Ke; Thi Phuong Phong, Nguyen

2009-09-01

202

De-alloyed platinum nanoparticles  

SciTech Connect

A method of producing de-alloyed nanoparticles. In an embodiment, the method comprises admixing metal precursors, freeze-drying, annealing, and de-alloying the nanoparticles in situ. Further, in an embodiment de-alloyed nanoparticle formed by the method, wherein the nanoparticle further comprises a core-shell arrangement. The nanoparticle is suitable for electrocatalytic processes and devices.

Strasser, Peter (Houston, TX); Koh, Shirlaine (Houston, TX); Mani, Prasanna (Houston, TX); Ratndeep, Srivastava (Houston, TX)

2011-08-09

203

In vivo sustained release of siRNA from solid lipid nanoparticles.  

PubMed

Small interfering RNA (siRNA) is a highly potent drug in gene-based therapy with a challenge of being delivered in a sustained manner. Nanoparticle drug delivery systems allow for incorporating and controlled release of therapeutic payloads. We demonstrate that solid lipid nanoparticles can incorporate and provide sustained release of siRNA. Tristearin solid lipid nanoparticles, made by nanoprecipitation, were loaded with siRNA (4.4-5.5 wt % loading ratio) using a hydrophobic ion pairing approach that employs the cationic lipid DOTAP. Intradermal injection of these nanocarriers in mouse footpads resulted in prolonged siRNA release over a period of 10-13 days. In vitro cell studies showed that the released siRNA retained its activity. Nanoparticles developed in this study offer an alternative approach to polymeric nanoparticles for encapsulation and sustained delivery of siRNA with the advantage of being prepared from physiologically well-tolerated materials. PMID:22077198

Lobovkina, Tatsiana; Jacobson, Gunilla B; Gonzalez-Gonzalez, Emilio; Hickerson, Robyn P; Leake, Devin; Kaspar, Roger L; Contag, Christopher H; Zare, Richard N

2011-12-27

204

48 Chemical Engineering Education Incorporating  

E-print Network

these to fields such as specialty chemical manufacture, green engineering, bio/pharmaceutical manufac- ture48 Chemical Engineering Education Incorporating GREEN ENGINEERING Into a Material and Energy prob- lems in chemical engineering. Problems of the type that can be used to motivate the student

Hesketh, Robert

205

Terminal supraparticle assemblies from similarly charged protein molecules and nanoparticles  

NASA Astrophysics Data System (ADS)

Self-assembly of proteins and inorganic nanoparticles into terminal assemblies makes possible a large family of uniformly sized hybrid colloids. These particles can be compared in terms of utility, versatility and multifunctionality to other known types of terminal assemblies. They are simple to make and offer theoretical tools for designing their structure and function. To demonstrate such assemblies, we combine cadmium telluride nanoparticles with cytochrome C protein and observe spontaneous formation of spherical supraparticles with a narrow size distribution. Such self-limiting behaviour originates from the competition between electrostatic repulsion and non-covalent attractive interactions. Experimental variation of supraparticle diameters for several assembly conditions matches predictions obtained in simulations. Similar to micelles, supraparticles can incorporate other biological components as exemplified by incorporation of nitrate reductase. Tight packing of nanoscale components enables effective charge and exciton transport in supraparticles and bionic combination of properties as demonstrated by enzymatic nitrate reduction initiated by light absorption in the nanoparticle.

Park, Jai Il; Nguyen, Trung Dac; de Queir鏀 Silveira, Gleiciani; Bahng, Joong Hwan; Srivastava, Sudhanshu; Zhao, Gongpu; Sun, Kai; Zhang, Peijun; Glotzer, Sharon C.; Kotov, Nicholas A.

2014-05-01

206

Structural integrity enhancement of graphite fiber composites using nanoparticles  

NASA Astrophysics Data System (ADS)

Graphite fibrous polymer composites with graphite nanoplatelets or single wall carbon nanotubes have been processed and tested for the mechanical and the electrical properties. Spray methods to incorporate nanoparticles into the composites were explored as a scalable processing method. Processing-microstructure-property relationship shows the promising aspects and the limitation of this processing method.

Kim, Han Sang

207

ANTIBACTERIAL ACTIVITY OF SILVER NANOPARTICLES SYNTHESIZED BY FUSARIUM OXYSPORUM STRAIN  

Microsoft Academic Search

Microorganisms (bacteria, yeast and fungi) play an important role in toxic metals remediation through reduction of metal ions, this was considered interesting as nanofactories. Recently, it was found that aqueous chloroaurate ions may be reduced extracellularly using Fusarium oxysporum, to generate extremely stable gold or silver nanoparticles in water. These particles can b e incorporated in materials and cloth becoming

P. D. Marcato; G. I. H. De Souza; O. L. Alves; E. Esposito; N. Dur嫕

208

Antisense Oligonucleotide Delivery with Polyhexylcyanoacrylate Nanoparticles as Carriers  

Microsoft Academic Search

Polyalkylcyanoacrylate nanoparticles are effective colloidal drug carriers and were prepared by an emulsion polymerization process. Antisense oligonucleotides were loaded on the particles by adsorption. A cationic polymer, DEAE-dextran, was incorporated into the particle matrix or a cationic hydrophobic detergent (CTAB) was used to form a lipophilic oligonucleotide ion pair. Enzymatic digestion of the oligonucleotides was almost quantitatively inhibited by this

Andreas Zimmer

1999-01-01

209

Self assembled gold nanoparticles wires by discontinuous vertical colloidal deposition  

Microsoft Academic Search

Materials at the nanoscale have recently attracted much attention due to their high potential for technological applications and to their size-dependent optical, nonlinear optical, electronic and chemical properties as well as their potential for incorporation into electronic circuits at the nanoscale. In particular, metal nanoparticles have been widely applied due to their ease of synthesis, stability and potential for application

A. Arbaoui; M. Reeves; Z. Hesham; J. Dumas

2008-01-01

210

Biodegradable Thermoplastic Polyurethanes Incorporating Polyhedral Oligosilsesquioxane  

E-print Network

Biodegradable Thermoplastic Polyurethanes Incorporating Polyhedral Oligosilsesquioxane Pamela T polyurethane (TPU) system that incorporates an organic, biodegradable poly(D,L- lactide) soft block with a hard

Mather, Patrick T.

211

A nanoparticle in plasma  

SciTech Connect

Charge and energy fluxes onto a nanoparticle under conditions typical of laboratory plasmas are investigated theoretically. Here, by a nanoparticle is meant a grain the size of which is much smaller than both the electron Larmor radius and Debye length and the thermionic emission from which is not limited by the space charge. Under conditions at which thermionic emission plays an important role, the electric potential and temperature T{sub p} of a nanoparticle are determined by solving a self-consistent set of equations describing the balance of energy and charge fluxes onto the nanoparticle. It is shown that, when the degree of plasma ionization exceeds a critical level, the potential of the nanoparticle and the energy flux onto it increase with increasing nanoparticle temperature, so that, starting from a certain temperature, the nanoparticle potential becomes positive. The critical degree of ionization starting from which the potential of a nanoparticle is always positive is determined as a function of the plasma density and electron temperature. The nanoparticle temperature T{sub p} corresponding to the equilibrium state of a positively charged nanoparticle is found as a function of the electron density for different electron temperatures.

Martynenko, Yu. V.; Nagel', M. Yu.; Orlov, M. A. [Russian Research Centre Kurchatov Institute (Russian Federation)

2009-06-15

212

Nanoparticles for Biomedical Imaging  

SciTech Connect

Background: Synthetic nanoparticles are emerging as versatile tools in biomedical applications, particularly in the area of biomedical imaging. Nanoparticles 1 to 100 nm in diameter possess dimensions comparable to biological functional units. Diverse surface chemistries, unique magnetic properties, tunable absorption and emission properties, and recent advances in the synthesis and engineering of various nanoparticles suggest their potential as probes for early detection of diseases such as cancer. Surface functionalization has further expanded the potential of nanoparticles as probes for molecular imaging. Objective: To summarize emerging research of nanoparticles for biomedical imaging with increased selectivity and reduced non-specific uptake with increased spatial resolution containing stabilizers conjugated with targeting ligands. Methods: This review summarizes recent technological advances in the synthesis of various nanoparticle probes, and surveys methods to improve the targeting of nanoparticles for their applications in biomedical imaging. Conclusion: Structural design of nanomaterials for biomedical imaging continues to expand and diversify. Synthetic methods have aimed to control the size and surface characteristics of nanoparticles to control distribution, half-life and elimination. Although molecular imaging applications using nanoparticles are advancing into clinical applications, challenges such as storage stability and long-term toxicology should continue to be addressed. Keywords: nanoparticle synthesis, surface modification, targeting, molecular imaging, and biomedical imaging.

Nune, Satish K.; Gunda, Padmaja; Thallapally, Praveen K.; Lin, Ying-Ying; Forrest, Laird M.; Berkland, Cory J.

2009-11-01

213

Monolithic cryopolymers with embedded nanoparticles. II. Capillary liquid chromatography of proteins using charged embedded nanoparticles.  

PubMed

The preparation of composite monolithic cryopolymers is presented. These novel porous materials were prepared in capillary format at -70蚓 using poly(ethyleneglycol) diacrylate (PEGDA) Mw 258 as the single monomer and a mixture of dioxane and water as the porogen. Positively (NR4(+)) or negatively (SO3(-)) charged nanoparticles were incorporated within the polymeric structure by direct addition of their suspensions to the polymerisation mixture. In contrast to our previous report using neutral nanoparticles, the trapping of charged nanoparticles is mostly observed at the polymer surface. The incorporation of these nanostructures improved the chromatographic separations of standard proteins under a hydrophobic interaction chromatography (HIC) separation mode. Moreover, the presence of ionic groups on the polymer surface allowed the application of these columns under ion-exchange (IEX) conditions. The results obtained in this work show that the functionalisation of monolithic columns by direct addition of nanoparticles is a good alternative towards the modification of monolithic polymers without altering the polymeric scaffold. PMID:24011507

Arrua, R Dario; Haddad, Paul R; Hilder, Emily F

2013-10-11

214

Spiropyran-based Photochromic Polymer Nanoparticles with Optically Switchable Luminescence  

PubMed Central

Emulsion polymerization yields 40400 nm diameter polymer nanoparticles with spiropyran-merocyanine dyes incorporated into their hydrophobic cavities; in contrast to their virtually nonfluorescent character in most environments, the merocyanine forms of the encapsulated dyes are highly fluorescent. Spiro-mero photoisomerization is reversible, allowing the fluorescence to be switched on and off by alternating UV and visible light. Immobilizing the dye inside hydrophobic pockets of nanoparticles also improves its photostability, rendering it more resistant than the same dyes in solution to fatigue effects arising from photochemical switching. The photophysical characteristics of the encapsulated fluorophores differ dramatically from those of the same species in solution, making nanoparticle-protected hydrophobic fluorophores attractive materials for potential applications such as optical data storage and switching and biological fluorescent labeling. To evaluate the potential for biological tagging, these optically addressable nanoparticles have been delivered into living cells and imaged with a liquid nitrogen cooled CCD. PMID:16569006

Zhu, Ming-Qiang; Zhu, Linyong; Han, Jason J.; Wuwei, Wu; Hurst, James K.; Li, Alexander D. Q.

2008-01-01

215

Spiropyran-based photochromic polymer nanoparticles with optically switchable luminescence.  

PubMed

Polymer nanoparticles of 40-400 nm diameter with spiropyran-merocyanine dyes incorporated into their hydrophobic cavities have been prepared; in contrast to their virtually nonfluorescent character in most environments, the merocyanine forms of the encapsulated dyes are highly fluorescent. Spiro-mero photoisomerization is reversible, allowing the fluorescence to be switched "on" and "off" by alternating UV and visible light. Immobilizing the dye inside hydrophobic pockets of nanoparticles also improves its photostability, rendering it more resistant than the same dyes in solution to fatigue effects arising from photochemical switching. The photophysical characteristics of the encapsulated fluorophores differ dramatically from those of the same species in solution, making nanoparticle-protected hydrophobic fluorophores attractive materials for potential applications such as optical data storage and switching and biological fluorescent labeling. To evaluate the potential for biological tagging, these optically addressable nanoparticles have been delivered into living cells and imaged with a liquid nitrogen-cooled CCD. PMID:16569006

Zhu, Ming-Qiang; Zhu, Linyong; Han, Jason J; Wu, Wuwei; Hurst, James K; Li, Alexander D Q

2006-04-01

216

A simple method to ordered mesoporous carbons containing nickel nanoparticles  

SciTech Connect

A series of ordered mesoporous carbons containing magnetic Ni nanoparticles (Ni-OMCs) with a variety of Ni loadings was made by a simple one-pot synthetic procedure through carbonization of phenolic resin-Pluronic block copolymer composites containing various amount of nickel nitrate. Such composite materials were characterized by N{sub 2} sorption, XRD, and STEM. Ni-OMCs exhibited high BET surface area, uniform pore size, and large pore volume without obvious pore blockage with a Ni loading as high as 15 wt%. Ni nanoparticles were crystalline with a face-center-cubic phase and observed mainly in the carbon matrix and on the outer surface as well. The average particle size of Ni nanoparticles was dependent on the preparation (carbonization) temperature and Ni loading; the higher the temperature was used and the more the Ni was incorporated, the larger the Ni nanoparticles were observed. One of the applications of Ni-OMCs was demonstrated as magnetically separable adsorbents.

Dai, Sheng [ORNL; Wang, Xiqing [ORNL

2009-01-01

217

Photoreversible fluorescent modulation of nanoparticles via one-step miniemulsion polymerization.  

PubMed

A nitrobenzoxadiazolyl(NBD)-based fluorescent dye and a photochromic spiropyran derivative are incorporated into polymeric nanoparticles via a one-step miniemulsion polymerization. The diameter of the nanoparticles can be varied from approximately 40 nm to 80 nm by adjusting the polymerization conditions. The prepared nanoparticles exhibit the spectral properties of both NBD dye and spiropyran, indicating that the two chromophores are incorporated into the nanoparticles. The determined amount of NBD and spiropyran in the nanoparticles are about approximately 85-90% of the feed amount, while the determined weight ratios of spiropyran to NBD in nanoparticles are very close to that of feed ratios, suggesting the miniemulsion polymerization is a suitable approach for incorporating multiple chromophores into individual nanoparticles with controlled amounts (content) and ratio. UV and visible light can be applied to modulate the fluorescence emission of NBD dye in nanoparticles. Upon UV irradiation, the spiropyran moieties in nanoparticles are converted to the open-ring (McH form) structure and upon visible-light irradiation they return to the closed-ring (SP form) structure; as a result, the fluorescence of NBD can be reversibly "switched off" and "switched on". Fluorescence resonance energy transfer from the excited NBD dye molecules to the McH form of the spiropyran moieties is the drives the fluorescence modulation. The nanoparticles display fairly good photoreversibility, photostability, and relatively fast photoresponsivity upon alternate UV/Vis irradiation. This class of photoresponsive nanoparticles may find applications in biological fields, such as labeling and imaging, as well as in optical fields, for example, individually light-addressable nanoscale devices. PMID:19235194

Chen, Jian; Zeng, Fang; Wu, Shuizhu; Su, Junhua; Tong, Zhen

2009-04-01

218

Mixed hemimicelles solid-phase extraction based on ionic liquid-coated Fe3O4/SiO2 nanoparticles for the determination of flavonoids in bio-matrix samples coupled with high performance liquid chromatography.  

PubMed

A novel magnetic solid-phase extraction (MSPE) method based on mixed hemimicelles of room temperature ionic liquids (RTILs) coated Fe3O4/SiO2 nanoparticles (NPs) was developed for simultaneous extraction of trace amounts of flavonoids in bio-matrix samples. A comparative study on the use of RTILs (C16mimBr) and CTAB-coated Fe3O4/SiO2 NPs as sorbents was presented. Owing to bigger adsorption amounts for analytes, RTILs-coated Fe3O4/SiO2 NPs was selected as MSPE materials and three analytes luteolin, quercetin and kaempferol can be quantitatively extracted and simultaneously determined coupled with high performance liquid chromatography (HPLC) in urine samples. No interferences were caused by proteins or endogenous compounds. Good linearity (R(2)>0.9993) for all calibration curves was obtained, and the limits of detection (LOD) for luteolin, quercetin and kaempferol were 0.10 ng/mL, 0.50 ng/mL and 0.20 ng/mL in urine samples, respectively. Satisfactory recoveries (93.5-97.6%, 90.1-95.4% and 93.3-96.6% for luteolin, quercetin and kaempferol) in biological matrices were achieved. It was notable that while using a small amount of Fe3O4/SiO2 NPs (4.0 mg) and C16mimBr (1.0 mg), satisfactory preconcentration factors and extraction recoveries for the three flavonoids were obtained. To the best of our knowledge, this is the first time a mixed hemimicelles MSPE method based on RTILs and Fe3O4/SiO2 NPs magnetic separation has ever been used for pretreatment of complex biological samples. PMID:24290172

He, Huan; Yuan, Danhua; Gao, Zhanqi; Xiao, Deli; He, Hua; Dai, Hao; Peng, Jun; Li, Nan

2014-01-10

219

Nanoparticles on Photovoltaic Performance of Fabricated DSSCs  

NASA Astrophysics Data System (ADS)

The present work focuses on the synthesis of mixed phase TiO2 nanoparticles with reduced band gaps without even being doped. The synthesis was carried out by chemical route followed by heat treatments at different temperatures to favor rutile incorporation in anatase network. The significance of different heat treatment temperatures on the phase composition of TiO2 nanoparticles and its effect on optical band gap and the photovoltaic performance are analyzed. The thermal analysis, phases, morphology, and energy band gap of as-synthesized TiO2 nanoparticles have been characterized by DTA/TG, x-ray diffraction, field-emission scanning electron microscope, transmission electron microscope, and UV-Vis-NIR, respectively. The results show the presence of rutile (~15 nm) and anatase phases (~17 nm) in "as-synthesized" TiO2 nanoparticles. TiO2 nanoparticles are heat treated for 2 h at 200, 400, and 600 蚓 in air. It is observed that heat treatment results in higher photoactivity in visible region of the solar radiation and the material demonstrated high photovoltaic performance in conjunction with N-719. The optical band gap values are found to be in the range of 2.59-2.88 eV. The dye-sensitized solar cells (DSSCs) fabricated by TiO2 nanoparticles, heat treated at 600 慢 show the energy conversion efficiency (?) of 6.08% with high photo current density ( J sc) of 11.76 mA/cm2. The work highlighted in this paper represents the realization of simple method of achieving low band gap semiconductors without being doped, for DSSCs applications.

Agarwala, Pooja; Makkar, Preeti; Sharma, Sarika; Garg, Rajnish

2014-10-01

220

Cytotoxicity assessment of heparin nanoparticles in NR8383 macrophages.  

PubMed

The bioavailability of low molecular weight heparin (LMWH) has been increased by encapsulation in nanoparticles. As a complement to these results, the cytotoxicity and apoptosis induced by LMWH nanoparticles prepared by two methods [nanoprecipitation (NP) and double emulsion (DE)] using Eudragit RS (RS) and poly-epsilon-caprolactone (PCL) have been analysed. Particle sizes varied from 54 to 400nm with zeta potential values between -65 and +63mV. Our results showed that the method of nanoparticle preparation affects their properties, especially in terms of drug incorporation and cell tolerance. Cell viability ranged from 6% to 100% depending on the preparation method and physicochemical properties of the particles and the type of toxicity assay. Particle diameter and zeta potential seemed to be the most valuable cytotoxicity markers when cell viability was measured by Trypan blue exclusion and MTT respectively. Nanoparticles prepared by DE were better tolerated than those of NP. LMWH encapsulation into the cationic nanoparticles reduces remarkably their toxicity. Apoptosis evaluation showed activated caspases in exposed cells. However, no nuclear fragmentation was detected in NR8383 cells whatever the tested nanoparticles. DE nanoparticles of RS and PCL can be proposed as a good LMWH delivery system due to their low toxicity (IC(50) approximately 2.33 and 0.96mg/mL, respectively). PMID:20542101

Eidi, H; Joubert, O; Attik, G; Duval, R E; Bottin, M C; Hamouia, A; Maincent, P; Rihn, B H

2010-08-30

221

Multifunctional gold nanoparticles for diagnosis and therapy of disease  

PubMed Central

Gold nanoparticles (AuNPs) have a number of physical properties that make them appealing for medical applications. For example, the attenuation of X-rays by gold nanoparticles has led to their use in computed tomography imaging and as adjuvants for radiotherapy. AuNPs have numerous other applications in imaging, therapy and diagnostic systems. The advanced state of synthetic chemistry of gold nanoparticles offers precise control over physicochemical and optical properties. Furthermore gold cores are inert and are considered to be biocompatible and non-toxic. The surface of gold nanoparticles can easily be modified for a specific application and ligands for targeting, drugs or biocompatible coatings can be introduced. AuNPs can be incorporated into larger structures such as polymeric nanoparticles or liposomes that deliver large payloads for enhanced diagnostic applications, efficiently encapsulate drugs for concurrent therapy or add additional imaging labels. This array of features has led to the afore-mentioned applications in biomedical fields, but more recently in approaches where multifunctional gold nanoparticles are used for multiple methods, such as concurrent diagnosis and therapy, so called theranostics. The following review covers basic principles and recent findings in gold nanoparticle applications for imaging, therapy and diagnostics, with a focus on reports of multifunctional AuNPs. PMID:23360440

Mieszawska, Aneta J.; Mulder, Willem J. M.; Fayad, Zahi A.

2013-01-01

222

Environmental Feedbacks and Engineered Nanoparticles: Mitigation of Silver Nanoparticle Toxicity to Chlamydomonas reinhardtii by Algal-Produced Organic Compounds  

PubMed Central

The vast majority of nanotoxicity studies measures the effect of exposure to a toxicant on an organism and ignores the potentially important effects of the organism on the toxicant. We investigated the effect of citrate-coated silver nanoparticles (AgNPs) on populations of the freshwater alga Chlamydomonas reinhardtii at different phases of batch culture growth and show that the AgNPs are most toxic to cultures in the early phases of growth. We offer strong evidence that reduced toxicity occurs because extracellular dissolved organic carbon (DOC) compounds produced by the algal cells themselves mitigate the toxicity of AgNPs. We analyzed this feedback with a dynamic model incorporating algal growth, nanoparticle dissolution, bioaccumulation of silver, DOC production and DOC-mediated inactivation of nanoparticles and ionic silver. Our findings demonstrate how the feedback between aquatic organisms and their environment may impact the toxicity and ecological effects of engineered nanoparticles. PMID:24086348

Stevenson, Louise M.; Dickson, Helen; Klanjscek, Tin; Keller, Arturo A.; McCauley, Edward; Nisbet, Roger M.

2013-01-01

223

Selenium incorporation using recombinant techniques.  

PubMed

Using selenomethionine to phase macromolecular structures is common practice in structure determination, along with the use of selenocysteine. Selenium is consequently the most commonly used heavy atom for MAD. In addition to the well established recombinant techniques for the incorporation of selenium in prokaryal expression systems, there have been recent advances in selenium labelling in eukaryal expression, which will be discussed. Tips and things to consider for the purification and crystallization of seleno-labelled proteins are also included. PMID:20382987

Walden, Helen

2010-04-01

224

Flexible Workflow Incorporated with RBAC  

Microsoft Academic Search

\\u000a In this paper, we propose a new model to incorporate RBAC into a flexible workflow system. Without compromising the flexibility\\u000a of workflow, this model can effectively enhance the security control of the user access to the workflow system. Specifically,\\u000a it provides the corresponding mechanism to maintain the constraint consistency in dynamic management of workflow. We present\\u000a the basic design and

Yuqing Sun; Xiangxu Meng; Shijun Liu; Peng Pan

2005-01-01

225

AuAg bimetallic nanoparticles: formation, silica-coating and selective etching.  

PubMed

A time-resolved study of the formation of AuAg alloy nanoparticles during boiling of AgNO3 and HAuCl4 in the presence of sodium citrate has been performed by monitoring the UV-visible spectra of the solutions. This study reveals clear differences with respect to the formation of pure Au particles, and suggests that gold and silver nanoparticles nucleate separately, but lattice rearrangement eventually leads to formation of alloy nanoparticles with the expected composition, which was confirmed by high resolution TEM. Additionally, we studied the chemical reaction of the alloy nanoparticles with NH4OH, observing that part of the Ag atoms get oxidized, but reorganization of the crystal lattice during the reaction prevents full transformation into pure gold nanoparticles. This allows the synthesis of silica-coated bimetallic particles with tailored plasmon resonance between ca. 430 and 520 nm, as well as homogeneous incorporation of the coated alloy nanoparticles within silica gels. PMID:14750668

Rodr璲uez-Gonz嫮ez, Benito; S嫕chez-Iglesias, Ana; Giersig, Michael; Liz-Marz嫕, Luis M

2004-01-01

226

Nanoparticles for Pulmonary Delivery  

Microsoft Academic Search

\\u000a This chapter aims to provide a rational for the use of nanoparticles in pulmonary delivery as well as an overview of strategies\\u000a and physiological implications of nanoparticle delivery to the lungs. Formulation aspects of nanoparticle systems in the form\\u000a of liquid dispersions and inhaled dry powders are also reviewed. The chapter also addresses the expanse of lung toxicology\\u000a research surrounding

Alan B. Watts; Robert O. Williams

227

Reactivity of Metal Nanoparticles  

NASA Astrophysics Data System (ADS)

This chapter will be concerned with the parameters governing interactions between metallic nanoparticles and a reactive surrounding material, and hence with the catalytic properties of such nanoparticles. Indeed, most industrial metal catalysts contain very costly metals, such as the precious metals at the end of the transition series and the noble metals, and must therefore have as large a surface-to-volume ratio as possible in order to economise the number of atoms required. This is the solution provided by nanoparticles.

Bertolini, J.-C.; Rousset, J.-L.

228

Stimulus responsive nanoparticles  

NASA Technical Reports Server (NTRS)

Disclosed are various embodiments of methods and systems related to stimulus responsive nanoparticles. In one embodiment includes a stimulus responsive nanoparticle system, the system includes a first electrode, a second electrode, and a plurality of elongated electro-responsive nanoparticles dispersed between the first and second electrodes, the plurality of electro-responsive nanorods configured to respond to an electric field established between the first and second electrodes.

Cairns, Darren Robert (Inventor); Huebsch, Wade W. (Inventor); Sierros, Konstantinos A. (Inventor); Shafran, Matthew S. (Inventor)

2013-01-01

229

Polymeric nanoparticles for molecular imaging.  

PubMed

Conventional imaging technologies (X-ray computed tomography, magnetic resonance, and optical) depend on contrast agents to visualize a target site or organ of interest. The imaging agents currently used in clinics for diagnosis suffer from disadvantages including poor target specificity and in vivo instability. Consequently, delivery of low concentrations of contrast agents to region of interest affects image quality. Therefore, it is important to selectively deliver high payload of contrast agent to obtain clinically useful images. Nanoparticles offer multifunctional capabilities to transport high concentrations of imaging probes selectively to diseased site inside the body. Polymeric nanoparticles, incorporated with contrast agents, have shown significant benefits in molecular imaging applications. These materials possess the ability to encapsulate different contrast agents within a single matrix enabling multimodal imaging possibilities. The materials can be surface conjugated to target-specific biomolecules for controlling the navigation under in vivo conditions. The versatility of this class of nanomaterials makes them an attractive platform for developing highly sensitive molecular imaging agents. The research community's progress in the area of synthesis of polymeric nanomaterials and their in vivo imaging applications has been noteworthy, but it is still in the pioneer stage of development. The challenges ahead should focus on the design and fabrication of these materials including burst release of contrasts agents, solubility, and stability issues of polymeric nanomaterials. PMID:24616442

Srikar, R; Upendran, Anandhi; Kannan, Raghuraman

2014-01-01

230

Nanoparticles for biomedical imaging  

PubMed Central

Background Synthetic nanoparticles are emerging as versatile tools in biomedical applications, particularly in the area of biomedical imaging. Nanoparticles 1 100 nm in diameter have dimensions comparable to biological functional units. Diverse surface chemistries, unique magnetic properties, tunable absorption and emission properties, and recent advances in the synthesis and engineering of various nanoparticles suggest their potential as probes for early detection of diseases such as cancer. Surface functionalization has expanded further the potential of nanoparticles as probes for molecular imaging. Objective To summarize emerging research of nanoparticles for biomedical imaging with increased selectivity and reduced nonspecific uptake with increased spatial resolution containing stabilizers conjugated with targeting ligands. Methods This review summarizes recent technological advances in the synthesis of various nanoparticle probes, and surveys methods to improve the targeting of nanoparticles for their application in biomedical imaging. Conclusion Structural design of nanomaterials for biomedical imaging continues to expand and diversify. Synthetic methods have aimed to control the size and surface characteristics of nanoparticles to control distribution, half-life and elimination. Although molecular imaging applications using nanoparticles are advancing into clinical applications, challenges such as storage stability and long-term toxicology should continue to be addressed. PMID:19743894

Nune, Satish K; Gunda, Padmaja; Thallapally, Praveen K; Lin, Ying-Ying; Forrest, M Laird; Berkland, Cory J

2011-01-01

231

Field emission scanning electron microscopy (FE-SEM) as an approach for nanoparticle detection inside cells.  

PubMed

When developing new nanoparticles for bio-applications, it is important to fully characterize the nanoparticle's behavior in biological systems. The most common techniques employed for mapping nanoparticles inside cells include transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM). These techniques entail passing an electron beam through a thin specimen. STEM or TEM imaging is often used for the detection of nanoparticles inside cellular organelles. However, lengthy sample preparation is required (i.e., fixation, dehydration, drying, resin embedding, and cutting). In the present work, a new matrix (FTO glass) for biological samples was used and characterized by field emission scanning electron microscopy (FE-SEM) to generate images comparable to those obtained by TEM. Using FE-SEM, nanoparticle images were acquired inside endo/lysosomes without disruption of the cellular shape. Furthermore, the initial steps of nanoparticle incorporation into the cells were captured. In addition, the conductive FTO glass endowed the sample with high stability under the required accelerating voltage. Owing to these features of the sample, further analyses could be performed (material contrast and energy-dispersive X-ray spectroscopy (EDS)), which confirmed the presence of nanoparticles inside the cells. The results showed that FE-SEM can enable detailed characterization of nanoparticles in endosomes without the need for contrast staining or metal coating of the sample. Images showing the intracellular distribution of nanoparticles together with cellular morphology can give important information on the biocompatibility and demonstrate the potential of nanoparticle utilization in medicine. PMID:25173605

Havrdova, M; Polakova, K; Skopalik, J; Vujtek, M; Mokdad, A; Homolkova, M; Tucek, J; Nebesarova, J; Zboril, R

2014-12-01

232

Holographic characteristics of citrate ion modified gold nano-particles dispersed photopolymer  

NASA Astrophysics Data System (ADS)

Hydrophilic photopolymers with AA as the monomer are versatile materials for use as holographic recording media. It has demonstrated a possibility to improve the refractive index modulation by doping inorganic nanoparticles into the polymer matrix. But the agglomerate effect of inorganic nanoparticles always deteriorate the holographic storage characteristics of the inorganic nanoparticle dispersed photopolymer compound materials. monodisperse hydrophilic gold nanoparticles are fabricated by the method of sodium citrate reduction, and then were dispersed into the PVA/AA photopolymer. Our results indicate that citrate ions coated on the surface of gold nanoparticles can effectively prevent the agglomerate effect, so that the gold nanoparticles can uniformly dispersed in the sol-gel photopolymer. The permanent refractive index grating can be formed owing to a spatial distribution of the effective refractive index with periodically distributed nanoparticles and polymerized monomers during the holographic recording. Furthermore, the citrate ion modified gold nanoparticles and polymer chain can induce the formation of hydrogen bonds which can prevent the material from distortion and at the same time improve the stability of the material by the coordination effect of carboxylate. Therefore, the incorporation of gold nanoparticles leads to a significantly improvement in the holographic properties of the materials, so that the volume shrinkage during the holographic exposure can be well suppressed. Additionally, there exists the optimum concentration of gold nanoparticles, at which the maximum diffraction efficiency can be as high as 90% and the volume shrinkage can be reduced to 0.8%.

Xue, Xiao-yu; Hai, Fu-Sheng; Gao, Li-Zhen; He, Fei; Li, Chun-Liu; Li, Yun-Xi; Huang, Ming-Ju

233

Microwave-induced synthesis of highly dispersed gold nanoparticles within the pore channels of mesoporous silica  

NASA Astrophysics Data System (ADS)

Highly dispersed gold nanoparticles have been incorporated into the pore channels of SBA-15 mesoporous silica through a newly developed strategy assisted by microwave radiation (MR). The sizes of gold are effectively controlled attributed to the rapid and homogeneous nucleation, simultaneous propagation and termination of gold precursor by MR. Diol moieties with high dielectric and dielectric loss constants, and hence a high microwave activation, were firstly introduced to the pore channels of SBA-15 by a simple addition reaction between amino group and glycidiol and subsequently served as the reduction centers for gold nanoparticles. Extraction of the entrapped gold from the nanocomposite resulted in milligram quantities of gold nanoparticles with low dispersity. The successful assembly process of diol groups and formation of gold nanoparticles were monitored and tracked by solid-state NMR and UV-vis measurements. Characterization by small angle X-ray diffraction (XRD) and transmission electron microscopy (TEM) indicated that the incorporation of gold nanoparticles would not breakup the structural integrity and long-range periodicity of SBA-15. The gold nanoparticles had a narrow size distribution with diameters in the size range of 5-10 nm through TEM observation. The average particles size is 7.9 nm via calculation by the Scherrer formula and TEM measurements. Nitrogen adsorption and desorption isotherms gave further evidence that the employed method was efficient and gold nanoparticles were successfully incorporated into the pore channels of SBA-15.

Gu, Jinlou; Fan, Wei; Shimojima, Atsushi; Okubo, Tatsuya

2008-04-01

234

Catechol-functionalized adhesive polymer nanoparticles for controlled local release of bone morphogenetic protein-2 from titanium surface.  

PubMed

We report on a novel surface functionalization approach to equip the titanium (Ti) surfaces with osteogenic properties. A key feature of the approach is the treatment of the Ti surfaces with Ti-adhesive nanoparticles that can stably load and controllably release bone morphogenetic protein-2 (BMP-2). Ti-adhesive nanoparticles were prepared by self-assembly of a catechol-functionalized poly(amino acid) diblock copolymer, catechol-poly(L-aspartic acid)-b-poly(L-phenylalanine) (Cat-PAsp-PPhe). The nanoparticles consist of Ti-adhesive peripheral catechol groups, anionic PAsp shells, and PPhe inner cores. Field-emission scanning electron microscopy (Fe-SEM) images showed that the Ti-adhesive nanoparticles could be uniformly immobilized on Ti surfaces. X-ray photoelectron spectroscopy (XPS) confirmed the successful anchoring of nanoparticles onto Ti surfaces. After surface immobilization of the nanoparticles, the static water contact angle of the Ti substrate decreased from 75.3 to 50.0 or 36.4, depending on the surface nanoparticle. Fluorescence microscopic analysis showed that BMP-2 could be effectively incorporated onto the Ti surface with adhesive nanoparticles. BMP-2 was controllably released for up to 40 days. The Ti substrate functionalized with BMP-2-incorporated nanoparticles significantly promoted attachment, proliferation, spreading, and alkaline phosphatase (ALP) activity of human adipose-derived stem cell (hADSC). The catechol-functionalized adhesive nanoparticles may be applied to various medical devices to create surfaces for improved performance. PMID:23727196

Lee, Hong Jae; Koo, Ahn Na; Lee, Suk Won; Lee, Myung Hyun; Lee, Sang Cheon

2013-09-10

235

Synthesis and Characterization of Nano-Silver Incorporated Natural Rubber Latex Foam  

Microsoft Academic Search

Synthesis and characterization of silver nanoparticles (SNP) incorporated natural rubber latex foam (NRLF) is described. SNP synthesized by reducing of Silver Nitrate (AgNO3) with Tri-Sodium Citrate (TSC) were adsorbed in-situ on to the NRLF matrix. Antimicrobial activities were tested by qualitatively and quantitatively against Gram positive Staphylococcus aureus and Gram negative Escherichia coli. It was found that the resultant NRLF

Indrajith Rathnayake; Hanafi Ismail; Baharin Azahari; Nalin Dammika Darsanasiri; Sanath Rajapakse

2012-01-01

236

Occupational risk management of engineered nanoparticles.  

PubMed

The earliest and most extensive societal exposures to engineered nanoparticles are likely to occur in the workplace. Until toxicologic and health effects research moves forward to characterize more broadly the potential hazards of nanoparticles and to provide a scientific basis for appropriate control of nanomaterials in the workplace, current and future workers may be at risk from occupational exposures. This article reviews a conceptual framework for occupational risk management as applied to engineered nanomaterials and describes an associated approach for controlling exposures in the presence of uncertainty. The framework takes into account the potential routes of exposure and factors that may influence biological activity and potential toxicity of nanomaterials; incorporates primary approaches based on the traditional industrial hygiene hierarchy of controls involving elimination or substitution, engineering controls, administrative controls, and use of personal protective equipment; and includes valuable secondary approaches involving health surveillance and medical monitoring. PMID:18260001

Schulte, Paul; Geraci, Charles; Zumwalde, Ralph; Hoover, Mark; Kuempel, Eileen

2008-04-01

237

Nanoparticles in drinking water  

Microsoft Academic Search

Synthetic nanoparticles are increasingly being used in everyday products, but little is known about environmental releases of these materials. Our knowledge of how many natural nanoparticles occur in drinking water is also inadequate. An initial assessment is presented here. Drinking water is clear, and yet it contains millions of particles. Substances are described as particulate - as opposed to dissolved

Ralf Kaegi

238

Biocompatible nanoparticles and biopolyelectrolytes  

NASA Astrophysics Data System (ADS)

The research presented in this manuscript encompasses a merger of two research directions: a study of aqueous nanoparticle colloids and a study of biological polyelectrolytes. The majority of biomedical applications of nanoparticles require stable aqueous colloids of nanoparticles as a starting point. A new one-step method of preparation of aqueous solutions of ultra-fine ferroelectric barium titanate nanoparticles was developed and generalized to the preparation of stable aqueous colloids of semiconductor nanoparticles. This high-energy ball milling technique is low cost, environmentally friendly, and allows for control of nanoparticle size by changing milling time. Aqueous colloids of BaTiO3 nanoparticles are stable over time, maintain ferroelectricity and can be used as second harmonic generating nanoprobes for biomedical imaging. Biopolyelectrolytes exhibit a variety of novel liquid-crystalline phases in aqueous solutions where their electrolytic nature is a driving force behind phase formation. We study medically relevant mixtures of F-actin, DNA and oppositely charged ions (such as multivalent salts and antibiotic drugs) and map out phase diagrams and laws that govern phase transitions. We combine these research directions in studies of the condensation behavior in aqueous solutions of biocompatible nanoparticles and biopolyelectrolytes.

Zribi, Olena

239

Inception to actualization: next generation coronary stent coatings incorporating nanotechnology.  

PubMed

Percutaneous coronary intervention (PCI) is used to treat blocked coronary arteries. Bare-metal stents (BMS) were first used in PCI but often necessitated repair procedures due to in-stent restenosis. Drug-eluting stents (DES) were developed to address this problem as the stent-incorporated anti-proliferative drugs prevented restenosis. However late-stent thrombosis arose with the use of DES due to polymer hypersensitivity and impaired re-endothelialization. Evidence suggests that using a combination of biofunctionalized polymers and antibody/peptide motifs can prevent thrombosis while ensuring in situ endothelialization. The advent of nanotechnology has engendered techniques like layer-by-layer self-assembly, and localized drug and gene delivery using nanoparticles. Therefore, this review seeks to explore the convergence of biotechnology and nanotechnology for the next generation coronary stent coatings, with an emphasis on its development from bench to beside. PMID:23376617

Tan, Aaron; Farhatnia, Yasmin; de Mel, Achala; Rajadas, Jayakumar; Alavijeh, Mohammad S; Seifalian, Alexander M

2013-03-10

240

Magnetic interactions between nanoparticles  

PubMed Central

Summary We present a short overview of the influence of inter-particle interactions on the properties of magnetic nanoparticles. Strong magnetic dipole interactions between ferromagnetic or ferrimagnetic particles, that would be superparamagnetic if isolated, can result in a collective state of nanoparticles. This collective state has many similarities to spin-glasses. In samples of aggregated magnetic nanoparticles, exchange interactions are often important and this can also lead to a strong suppression of superparamagnetic relaxation. The temperature dependence of the order parameter in samples of strongly interacting hematite nanoparticles or goethite grains is well described by a simple mean field model. Exchange interactions between nanoparticles with different orientations of the easy axes can also result in a rotation of the sub-lattice magnetization directions. PMID:21977409

Hansen, Mikkel Fougt; Frandsen, Cathrine

2010-01-01

241

Covalently functionalized gold nanoparticles: Synthesis, characterization, and integration into capillary electrophoresis  

NASA Astrophysics Data System (ADS)

Nanomaterials are widely used as pseudostationary and stationary phases in electrically driven separations. The advantages of using nanomaterials are numerous including tunable sizes, multiple core compositions, flexible injection schemes, and diverse surface chemistries. Nanomaterials, however, exhibit large surface energies which induce aggregation and may yield unpredictable function in separations. Because nanomaterials can modify buffer conductivity, viscosity, and pH; successful and systematic incorporation of nanomaterials into separations requires rigorous synthetic control and characterization of both the nanoparticle core and surface chemistry. This dissertation investigates the impact of gold nanoparticle surface chemistry and morphology to capillary electrophoresis separations. Gold nanoparticle core composition, shape, size, self assembled monolayer (SAM) formation, and SAM packing density are quantified for gold nanoparticles functionalized with thioctic acid, 6-mercaptohexanoic acid, or 11-mercaptoundecanoic acid SAMs. TEM, 1H NMR, extinction spectroscopy, zeta potential, X-ray photoelectron spectroscopy, and flocculation assess the morphology, surface chemistry, optical properties, surface charge, SAM packing density, and stability of the nanoparticles, respectively. Using well-characterized nanostructures, pseudostationary phases of gold nanoparticles in capillary electrophoresis are studied. Gold nanoparticles functionalized with thioctic acid and either 6-mercaptohexanoic acid or 6-aminohexanethiol impact the mobility of analytes in a concentration and surface chemistry-dependent manner. From these data, a novel parameter termed the critical nanoparticle concentration is developed and is used to estimate nanoparticle stability during capillary electrophoresis separations. To understand the function of carboxylated gold nanoparticles in capillary electrophoresis, extended DLVO theory is used to model interparticle interactions. Nanoparticle aggregation leads to electron tunneling between nanoparticles thereby taking on bulk electrical properties which cause measured currents to increase for nanoparticles functionalized with poorly ordered SAMs. Nanoparticles functionalized with well-ordered SAMs main their nanoscale properties and reduce measured currents during electrically driven flow. Finally, carboxylic acid functionalized gold nanoparticles effect the separation of target biomarkers in both a SAM composition and surface coverage dependent manner. These effects are most systematic with well ordered SAMs. To understand the separation mechanism functionalized gold nanoparticles exhibit, their ? potential with and without dopamine are evaluated. Large dopamine concentrations neutralize the three functionalized gold nanoparticles according to a dose response curve. The positively charged dopamine molecules saturate the negatively charged nanoparticle surfaces thereby providing a plausible explanation to the observed biomarker concentration trends. These data and future work provide a rigorous experimental and theoretical evaluation of nanoparticle structure impacts their function as pseudostationary phases in separations and other applications.

Ivanov, Michael Robert

242

Magnetic Nanoparticle Degradation in vivo Studied by M飉sbauer Spectroscopy  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles belong to the most promising nanosized objects for biomedical applications. However, little is known about clearance of magnetic nanoparticles from the organism. In this work superparamagnetic iron oxide particles fluidMAG-ARA were injected into tail vein of mice at a dose of 17 mg per 20 g body weight. At various time intervals after the injection the mice were sacrificed and their organs collected. A M飉sbauer study allowed to detect magnetic particles in the liver and spleen and showed the degradation of the particles with incorporation of exogenous iron into paramagnetic ferritin-like iron species.

Nikitin, Maxim; Gabbasov, Raul; Cherepanov, Valery; Chuev, Mikhail; Polikarpov, Mikhail; Panchenko, Vladislav; Deyev, Sergey

2010-12-01

243

Tea-bag-like polymer nanoreactors filled with gold nanoparticles.  

PubMed

Gold-containing polymer nanotubes, which showed both catalytic activity and resistance to leaching, were prepared by the "tubes by fiber templates" (TUFT) process. For this purpose, electrospun polymer nonwovens with incorporated poly(L-lactide)-stabilized gold nanoparticles were coated with poly(p-xylylene) by the chemical vapor deposition process, and then the inner fiber templates were removed. The resulting polymer tubes carried encapsulated gold nanoparticles which were shown to be immobilized and featured pronounced catalytic activity towards the hydrolytic oxidation of dimethylphenylsilane and the alcoholysis of dimethylphenylsilane with n-butanol. The macroscopic nonwovens could be used as tea-bag-like catalyst systems and showed excellent reusability. PMID:24700456

Mitschang, Fabian; Schmalz, Holger; Agarwal, Seema; Greiner, Andreas

2014-05-01

244

The Effect of Zr Incorporation Caused by Ball Abrasion in a Milled Fe-Y2O3 Model Alloy  

NASA Astrophysics Data System (ADS)

Y-O nanoparticles which are homogeneously distributed in the matrix can improve the thermal properties of steels. Several studies of mechanically alloyed steels showed that especially Y-Ti-O particles can cause a further improvement of the mechanical properties at elevated temperatures. It is also assumed that an addition of Zr instead of Ti may have a similar or even stronger effect. This study presents a new way of producing nanostructured ferritic alloys as Zr is incorporated by attrition of yttrium-stabilized zirconia balls during milling. Additionally, the effect of Zr incorporation is demonstrated as well as the particle size distribution of the Y-Zr-O nanoparticles analyzed by transmission electron microscopy. This is compared to a specimen milled with common steel balls. Atom probe tomography and transmission electron microscopy show that the incorporated zirconia lowers the minimum particle size and causes a finer particle distribution. This particle refinement causes a higher hardness after hipping.

Ressel, Gerald; Primig, Sophie; Leitner, Harald

2013-10-01

245

Measuring and Incorporating Vulnerability into Conservation Planning  

E-print Network

FORUM Measuring and Incorporating Vulnerability into Conservation Planning KERRIE WILSON / Conservation planning is the process of locating and designing conservation areas to promote the persistence, measuring and incorporating vul- nerability into conservation planning have been problematic. We develop

Queensland, University of

246

Targeted Nanoparticles Assembled via Complexation of Boronic Acid-Containing Targeting Moieties to Diol-Containing Polymers  

PubMed Central

The delivery of therapeutics via nanoscaled vehicles for solid cancer treatment can be enhanced by the incorporation of a targeting capability. Here, we describe a new method for assembling a targeted nanoparticle that utilizes the reversible covalent complexation between boronic acids and diols to achieve a targeted nanoparticle for the delivery of anti-cancer drug, camptothecin (CPT). CPT is conjugated to a biocompatible, hydrophilic copolymer of mucic acid and PEG (MAP). When this polymer-drug conjugate is placed in water, it self-assembles into MAP-CPT nanoparticles of ca. 30 nm (diameter) and slightly negative zeta potential. The antibody Herceptin is attached to a boronic acid via a polyethylene glycol (PEG) spacer, and this boronic acid-containing targeting moiety is complexed with the diol-containing MAP to form a targeted MAP-CPT nanoparticle. The addition of Herceptin targeting agent to the MAP-CPT nanoparticles yields targeted MAP-CPT nanoparticles with increased nanoparticle size to ca. 40 nm (diameter). The main mechanisms of CPT release from MAP-CPT nanoparticles are found by in vitro analysis to be hydrolysis and nanoparticle disruption by fat. Cellular uptake of nanoparticles is enhanced by 70% compared to non-targeted version by the incorporation of a single Herceptin antibody targeting agent per nanoparticle. This single Herceptin antibody targeted MAP-CPT nanoparticle system carries ca. 60 CPT molecules per nanoparticle and shows prolonged plasma circulation with an elimination half-life of 21.2 h and AUC value of 2766 ?g.h/ml at a 10 mg CPT/kg tail vein injection in mice. PMID:23461746

Han, Han; Davis, Mark E.

2013-01-01

247

Prevention of coalescence during annealing of FePt nanoparticles assembled by convective coating.  

PubMed

FePt nanoparticle suspension was synthesized by reduction of platinum acetylacetonate and decomposition of iron pentacarbonyl in the presence of oleic acid and oleyl amine. The composition of the synthesized nanoparticles was Fe40Pt60. To prevent the coalescence during annealing of FePt nanoparticles we tried two steps of convective coating, where first coating was for silica particle assembly on a silicon substrate and second one was for FePt nanoparticles on the silica layers. It was observed by scanning electron microscopy that FePt nanoparticles were dispersed on the silica surface. After being annealed at 700 degrees C for 30 minutes under nitrogen atmosphere, the particle size of FePt nanoparticles increased slightly from 4 nm to 6 nm but dispersity of the nanoparticles was maintained. Magnetic hysteresis of Fe40Pt60 nanoparticles coating on silica layer after annealing showed typical characteristics of hard magnetic materials, and no incorporation of soft magnetic materials. It was suggested that convective self-assembly with the parallel use of pre-coating that offers solvent flux weakening capillary force between FePt nanoparticles was an effective method to prevent coalescence of nano-sized particles under high temperature annealing. PMID:20358990

Hwang, Yeon; Park, Jong-Sung; Choi, Young Jin; Suh, Yong Jae; Lee, Hyo-Sook; Kang, Dae Sik; Lee, Jong Kook

2010-05-01

248

Synthesis and optical studies of CdSe nanoparticles\\/ferroelectric thin film hybrid materials  

Microsoft Academic Search

Ferroelectric thin films have attracted recent research attention due to their promise as thin film photovoltaic devices. Due to the large bandgap of the ferroelectric, these films absorb weakly in the region of the solar spectrum. Meanwhile, semiconductor nanoparticles exhibit tunable absorption which can be tailored through size-selective synthesis techniques. We report on low-temperature chemical synthesis to incorporate CdSe nanoparticles

Elizabeth Bushong; J. K. Krebs; Katherine E. Plass

2010-01-01

249

Microstructural and Pinning Properties of Thin Films Doped With Magnetic Nanoparticles  

Microsoft Academic Search

In this paper, we report a strong enhancement in the in-field transport properties of the YBa2Cu3O7-delta (YBCO) thin films doped with magnetic Fe2O3 nanoparticles. We incorporated magnetic Fe2O3 nanoparticles with two different architectures by laser ablation of the YBCO and dopant targets. YBCO film thickness was controlled at around 1 mum for all the samples. We conducted a detailed microstructural

Jie Wang; Chen-Fong Tsai; Zhenxing Bi; Donald G. Naugle; Haiyan Wang

2009-01-01

250

Enhancement of tumor thermal therapy using gold nanoparticle-assisted tumor necrosis factor-A delivery  

Microsoft Academic Search

Tumor necrosis factor-A (TNF-A) is a potent cytokine with anticancer efficacy that can significantly enhance hyper- thermic injury. However, TNF-A is systemically toxic, thereby creating a need for its selective tumor delivery. We used a newly developed nanoparticle delivery system consisting of 33-nm polyethylene glycol - coated colloidal gold nanoparticles (PT-cAu-TNF-A) with incorporated TNF-A payload (several hundred TNF-A molecules per

Rachana K. Visaria; Robert J. Griffin; Brent W. Williams; Emad S. Ebbini; Giulio F. Paciotti; Chang W. Song; John C. Bischof

2006-01-01

251

Solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) in cosmetic and dermatological preparations  

Microsoft Academic Search

Solid lipid nanoparticles (SLN) were developed at the beginning of the 1990s as an alternative carrier system to emulsions, liposomes and polymeric nanoparticles. The paper reviews advantagesalso potential limitationsof SLN for the use in topical cosmetic and pharmaceutical formulations. Features discussed include stabilisation of incorporated compounds, controlled release, occlusivity, film formation on skin including in vivo effects on the skin.

R. H. Mller; M. Radtke; S. A. Wissing

2002-01-01

252

Direct Electrochemistry of Cytochrome bo3 Oxidase at a series of Gold Nanoparticles-Modified Electrodes  

PubMed Central

New membrane-protein based electrodes were prepared incorporating cytochrome bo3 from E. coli and gold nanoparticles. Direct electron transfer between the electrode and the immobilized enzymes was achieved, resulting in an electrocatalytic activity in presence of O2. The size of the gold nanoparticles was shown to be important and smaller particles were shown to reduce the overpotential of the process. PMID:23335854

Melin, Frederic; Meyer, Thomas; Lankiang, Styven; Choi, Sylvia K.; Gennis, Robert B; Blanck, Christian; Schmutz, Marc; Hellwig, Petra

2012-01-01

253

Ensemble learning incorporating uncertain registration.  

PubMed

This paper proposes a novel approach for improving the accuracy of statistical prediction methods in spatially normalized analysis. This is achieved by incorporating registration uncertainty into an ensemble learning scheme. A probabilistic registration method is used to estimate a distribution of probable mappings between subject and atlas space. This allows the estimation of the distribution of spatially normalized feature data, e.g., grey matter probability maps. From this distribution, samples are drawn for use as training examples. This allows the creation of multiple predictors, which are subsequently combined using an ensemble learning approach. Furthermore, extra testing samples can be generated to measure the uncertainty of prediction. This is applied to separating subjects with Alzheimer's disease from normal controls using a linear support vector machine on a region of interest in magnetic resonance images of the brain. We show that our proposed method leads to an improvement in discrimination using voxel-based morphometry and deformation tensor-based morphometry over bootstrap aggregating, a common ensemble learning framework. The proposed approach also generates more reasonable soft-classification predictions than bootstrap aggregating. We expect that this approach could be applied to other statistical prediction tasks where registration is important. PMID:23288332

Simpson, Ivor J A; Woolrich, Mark W; Andersson, Jesper L R; Groves, Adrian R; Schnabel, Julia A

2013-04-01

254

Facet-Specific Chemistry of Noble Metal Nanoparticles Using an Enhanced Scattering Infrared Scanning Near-Field Optical Microscope  

E-print Network

spectroscopic identification and spatial resolution, combining atomic force microscopy with quantum cascade incorporation of EC-QCLs of different wavelengths; with appropriately selected laser can have applications nanoparticles s-IR SNOM system incorporated into EMSL as a user-accessible capability Complex index

255

Cooperative plasmonic effect of Ag and Au nanoparticles on enhancing performance of polymer solar cells.  

PubMed

This article describes a cooperative plasmonic effect on improving the performance of polymer bulk heterojunction solar cells. When mixed Ag and Au nanoparticles are incorporated into the anode buffer layer, dual nanoparticles show superior behavior on enhancing light absorption in comparison with single nanoparticles, which led to the realization of a polymer solar cell with a power conversion efficiency of 8.67%, accounting for a 20% enhancement. The cooperative plasmonic effect aroused from dual resonance enhancement of two different nanoparticles. The idea was further unraveled by comparing Au nanorods with Au nanoparticles for solar cell application. Detailed studies shed light into the influence of plasmonic nanostructures on exciton generation, dissociation, and charge recombination and transport inside thin film devices. PMID:23237567

Lu, Luyao; Luo, Zhiqiang; Xu, Tao; Yu, Luping

2013-01-01

256

Nanoparticle-Based Systems for T1-Weighted Magnetic Resonance Imaging Contrast Agents  

PubMed Central

Because magnetic resonance imaging (MRI) contrast agents play a vital role in diagnosing diseases, demand for new MRI contrast agents, with an enhanced sensitivity and advanced functionalities, is very high. During the past decade, various inorganic nanoparticles have been used as MRI contrast agents due to their unique properties, such as large surface area, easy surface functionalization, excellent contrasting effect, and other size-dependent properties. This review provides an overview of recent progress in the development of nanoparticle-based T1-weighted MRI contrast agents. The chemical synthesis of the nanoparticle-based contrast agents and their potential applications were discussed and summarized. In addition, the recent development in nanoparticle-based multimodal contrast agents including T1-weighted MRI/computed X-ray tomography (CT) and T1-weighted MRI/optical were also described, since nanoparticles may curtail the shortcomings of single mode contrast agents in diagnostic and clinical settings by synergistically incorporating functionality. PMID:23698781

Zhu, Derong; Liu, Fuyao; Ma, Lina; Liu, Dianjun; Wang, Zhenxin

2013-01-01

257

Cobalt driven enhancement of nanomagnetism in iron-oxide nanoparticles encapsulated in a synthetic ferritin shell  

NASA Astrophysics Data System (ADS)

We have examined the effects of Co doping (0-12% relative to total metal) on the magnetic properties of iron-oxide nanoparticles incorporated in a synthetic ferritin shell. M飉sbauer spectroscopy revealed that the nanoparticles consisted of a mixture of Fe3 O4 and ?-Fe2 O3, and that Co was integrated exclusively into the B-sites of the Fe3 O4 phase. Cobalt doping resulted in the formation of Cox Fe3-x O4/?-Fe2 O3 nanoparticles with x = 0, 0.25, 0.51, 0.56, and 0.63. Magnetometry and susceptometry experiments showed that substantial enhancements in the coercivities, blocking temperatures and anisotropy constants of the magnetoferritin nanoparticles occurred for all Co doping levels. Our results show that the Co altered significantly the local atomic Fe magnetism and enhanced the magnetic nanoparticle anisotropy considerably.

Skoropata, E.; Ceci, P.; Kasyutich, O.; van Lierop, J.

2012-04-01

258

Enhancement of the near-band-edge photoluminescence of ZnO nanowires: Important role of hydrogen incorporation versus plasmon resonances  

SciTech Connect

We investigated the photoluminescence properties of ZnO nanowires coated with Au, Ag, and Pt nanoparticles deposited by dc sputtering. A strong enhancement of the near-band-edge emission was observed in all metal-coated samples but also if the samples were treated with Ar plasma without any nanoparticle deposition. High-resolution photoluminescence spectroscopy revealed hydrogen-donor-bound-exciton emission in all samples indicating unintentional hydrogen incorporation. A shorter decay time of the near-band-edge emission was observed in all cases. The results indicate that unintentional hydrogen incorporation plays a dominant role when metal deposition is performed by sputtering.

Dev, A.; Richters, J. P.; Gutowski, J.; Voss, T. [Institute of Solid State Physics, University of Bremen, D-28359 Bremen (Germany); Sartor, J.; Kalt, H. [Institute for Applied Physics, Karlsruhe Institute of Technology, D-76131 Karlsruhe (Germany)

2011-03-28

259

Nanoparticles & Quantum Dots  

E-print Network

formed by citrate reduction 簫 PEG linker 簫 Oxaliplatin attched to linker #12;SEM imaging of Au.J.Wheate "Oxaliplatin tethered gold nanoparticles for improved anticancer drug delivery" 繚 In vitro cytotoxicity tests

Strathclyde, University of

260

Divalent metal nanoparticles  

E-print Network

Metal nanoparticles hold promise for many scientific and technological applications, such as chemical and biological sensors, vehicles for drug delivery, and subdiffraction limit waveguides. To fabricate such devices, a ...

DeVries, Gretchen Anne

2008-01-01

261

New strategies for luminescence thermometry in the biological range using upconverting nanoparticles  

NASA Astrophysics Data System (ADS)

We have studied different strategies of use of luminescence thermometry with upconverting nanoparticles in the biological range of temperatures, among them, the thermal sensing ability of fluoresncent lifetime of Er,Yb:NaY2F5 nanoparticles. Er,Yb:NaY2F5O nanocrystals show great potentiality as thermal sensors at the nanoscale for biomedical applications due to the incorporation of additional non-radiative relaxation mechanisms that shorten the emission lifetime generated by the oxygen present in the structure. Here we report ex-vivo temperature determination by laser induced heating in chicken breast using lifetime-based thermometry in these up-conversion nanoparticles.

Savchuk, Ol. A.; Carvajal, J. J.; Pujol, M. C.; Massons, J.; Haro-Gonz嫮ez, P.; Jaque, D.; Aguil, M.; D燰z, F.

2014-05-01

262

High-harmonic generation by nonlinear resonant excitation of surface plasmon modes in metallic nanoparticles  

NASA Astrophysics Data System (ADS)

The nonlinear electron dynamics in metallic nanoparticles is studied using a hydrodynamic model that incorporates most quantum many-body features, including spill-out and nonlocal effects as well as electron exchange and correlations. We show that, by irradiating the nanoparticle with a chirped laser pulse of modest intensity (autoresonance), it is possible to drive the electron dynamics far into the nonlinear regime, leading to enhanced energy absorption and complete ionization of the nanoparticle on a time scale of the order of 100 fs. The accompanying radiated power spectrum is rich in high-order harmonics.

Hurst, J廨獽e; Haas, Fernando; Manfredi, Giovanni; Hervieux, Paul-Antoine

2014-04-01

263

Photoluminescence spectroscopy and lifetime measurements from self-assembled semiconductor-metal nanoparticle hybrid arrays.  

SciTech Connect

We present results of photoluminescence spectroscopy and lifetime measurements on thin film hybrid arrays of semiconductor quantum dots and metal nanoparticles embedded in a block copolymer template. The intensity of emission as well as the measured lifetime would be controlled by varying the volume fraction and location of gold nanoparticles in the matrix. We demonstrate the ability to both enhance and quench the luminescence in the hybrids as compared to the quantum dot array films while simultaneously engineering large reduction in luminescence lifetime with incorporation of gold nanoparticles.

Haridas, M.; Basue, J. K.; Gosztola, D. J.; Wiederrecht, G. P. (Center for Nanoscale Materials); (Indian Inst. of Science)

2010-08-23

264

Spray-coated nanoscale conductive patterns based on in situ sintered silver nanoparticle inks  

NASA Astrophysics Data System (ADS)

Nanoscale patterns with high conductivity based on silver nanoparticle inks were fabricated using spray coating method. Through optimizing the solution content and spray operation, accurate nanoscale patterns consisting of silver nanoparticles with a square resistance lower than 1 ? /cm2 were obtained. By incorporating in situ sintering to substitute the general post sintering process, the time consumption could be significantly reduced to one sixth, qualifying it for large-scale and cost-effective fabrication of printed electronics. To testify the application of spray-coated silver nanoparticle inks, an inverted polymer solar cell was also fabricated, which exhibited a power conversion efficiency of 2.76%.

Zheng, Yifan; Li, Shuguang; Shi, Wei; Yu, Junsheng

2014-03-01

265

Inflamed Leukocyte-mimetic Nanoparticles for Molecular Imaging of Inflammation  

PubMed Central

Dysregulated host inflammatory response causes many diseases, including cardiovascular and neurodegenerative diseases, cancer, and sepsis. Sensitive detection of the site of inflammation will, therefore, produce a wide-ranging impact on disease diagnosis and treatment. We hypothesized that nanoprobes designed to mimic the molecular interactions occurring between inflamed leukocytes and endothelium may possess selectivity toward diverse host inflammatory responses. To incorporate inflammation-sensitive molecular interactions, superparamagnetic iron oxide nanoparticles were conjugated with integrin lymphocyte function-associated antigen (LFA)-1 I domain, engineered to mimic activated leukocytes in physiology. Whole body optical and magnetic resonance imaging in vivo revealed that leukocyte-mimetic nanoparticles localized preferentially to the vasculature within and in the invasive front of the tumor, as well as to the site of acute inflammation. This study explored in vivo detection of tumor-associated vasculature with systemically injected inflammation-specific nanoparticles, presenting a possibility of tumor detection by inflamed tumor microenvironment. PMID:21783245

Chen, Xiaoyue; Wong, Richard; Khalidov, Ildar; Wang, Y. Andrew; Leelawattanachai, Jeerapond; Wang, Yi; Jin, Moonsoo M.

2011-01-01

266

Importance of the DNA "bond" in programmable nanoparticle crystallization.  

PubMed

If a solution of DNA-coated nanoparticles is allowed to crystallize, the thermodynamic structure can be predicted by a set of structural design rules analogous to Pauling's rules for ionic crystallization. The details of the crystallization process, however, have proved more difficult to characterize as they depend on a complex interplay of many factors. Here, we report that this crystallization process is dictated by the individual DNA bonds and that the effect of changing structural or environmental conditions can be understood by considering the effect of these parameters on free oligonucleotides. Specifically, we observed the reorganization of nanoparticle superlattices using time-resolved synchrotron small-angle X-ray scattering in systems with different DNA sequences, salt concentrations, and densities of DNA linkers on the surface of the nanoparticles. The agreement between bulk crystallization and the behavior of free oligonucleotides may bear important consequences for constructing novel classes of crystals and incorporating new interparticle bonds in a rational manner. PMID:25298535

Macfarlane, Robert J; Thaner, Ryan V; Brown, Keith A; Zhang, Jian; Lee, Byeongdu; Nguyen, SonBinh T; Mirkin, Chad A

2014-10-21

267

Formation of titanium nitride nanoparticles within mesoporous silica SBA-15.  

PubMed

We report the first synthesis of titanium nitride (TiN) nanoparticles inside the nanoscale channels of mesoporous silica SBA-15. The TiN precursor, Ti(NMe(2))(4) in toluene, was incorporated into the methyl group-modified channels of the SBA-15 powder. The functionalization of pore surfaces with methyl groups generates hydrophobic surfaces that facilitate impregnation with Ti(NMe(2))(4) and minimizes reactions between the TiN precursor and the hydroxyl groups on the surface of SBA-15. Formation of TiN nanoparticles inside the mesoporous channels of SBA-15 was carried out by subsequent ammonolysis at high temperatures (700-750 degrees C). The final products have been characterized by TEM and EELS images, powder XRD patterns, FTIR spectra, UV-vis absorption spectra, and nitrogen adsorption isotherm measurements to confirm the presence and distribution of TiN nanoparticles in the SBA-15 samples. PMID:16851509

Hsueh, Han-Sheng; Yang, Cheng-Tzu; Zink, Jeffrey I; Huang, Michael H

2005-03-17

268

Engines and nanoparticles  

Microsoft Academic Search

Most of the particle number emitted by engines is in the nanoparticle range, Dp<50 nm, while most of the mass is in the accumulation mode, 50nmNanoparticles are typically hydrocarbons or sulfate and form by nucleation during dilution and cooling of the exhaust, while accumulation mode particles are mainly carbonaceous soot agglomerates formed directly by combustion. Emission standards

David B. Kittelson

1998-01-01

269

Functional nanoparticles in cells  

NASA Astrophysics Data System (ADS)

In this paper we present an overview of our recent studies regarding the interactions of functional nanoparticles with the human umbilical endothelial cells (HUVECs). Cellular uptake, cytotoxicity and laser hyperthermia of cells loaded with gold nanoparticles are discussed. Particles with different shape, size and charge are compared and evaluated to conclude at the most appropriate types for specific biomedical applications (i.e. drug delivery, laser hyperthermia).

Bartczak, Dorota; Muskens, Otto L.; Nitti, Simone; Sanchez-Elsner, Tilman; Millar, Timothy M.; Kanaras, Antonios G.

2012-03-01

270

Effects of Gold Nanoparticles on the Response of Phenol Biosensor Containing Photocurable Membrane with Tyrosinase  

PubMed Central

The role of incorporation of gold nanoparticles (50-130 nm in diameter) into a series of photocurable methacrylic-acrylic based biosensor membranes containing tyrosinase on the response for phenol detection was investigated. Membranes with different hydrophilicities were prepared from 2-hydroxyethyl methacrylate and n-butyl acrylate via direct photocuring. A range of gold nanoparticles concentrations from 0.01 to 0.5 % (w/w) was incorporated into these membranes during the photocuring process. The addition of gold nanoparticles to the biosensor membrane led to improvement in the response time by a reduction of approximately 5 folds to give response times of 5-10 s. The linear response range of the phenol biosensor was also extended from 24 to 90 ?M of phenol. The hydrophilicities of the membrane matrices demonstrated strong influence on the biosensor response and appeared to control the effect of the gold nanoparticles. For less hydrophilic methacrylic-acrylic membranes, the addition of gold nanoparticles led to a poorer sensitivity and detection limit of the biosensor towards phenol. Therefore, for the application of gold nanoparticles in the enhancement of a phenol biosensor response, the nanoparticles should be immobilized in a hydrophilic matrix rather than a hydrophobic material.

Hanifah, Sharina Abu; Heng, Lee Yook; Ahmad, Musa

2008-01-01

271

Drug Delivery Nanoparticles in Skin Cancers  

PubMed Central

Nanotechnology involves the engineering of functional systems at nanoscale, thus being attractive for disciplines ranging from materials science to biomedicine. One of the most active research areas of the nanotechnology is nanomedicine, which applies nanotechnology to highly specific medical interventions for prevention, diagnosis, and treatment of diseases, including cancer disease. Over the past two decades, the rapid developments in nanotechnology have allowed the incorporation of multiple therapeutic, sensing, and targeting agents into nanoparticles, for detection, prevention, and treatment of cancer diseases. Nanoparticles offer many advantages as drug carrier systems since they can improve the solubility of poorly water-soluble drugs, modify pharmacokinetics, increase drug half-life by reducing immunogenicity, improve bioavailability, and diminish drug metabolism. They can also enable a tunable release of therapeutic compounds and the simultaneous delivery of two or more drugs for combination therapy. In this review, we discuss the recent advances in the use of different types of nanoparticles for systemic and topical drug delivery in the treatment of skin cancer. In particular, the progress in the treatment with nanocarriers of basal cell carcinoma, squamous cell carcinoma, and melanoma has been reported. PMID:25101298

Dianzani, Chiara; Zara, Gian Paolo; Maina, Giovanni; Pettazzoni, Piergiorgio; Pizzimenti, Stefania; Rossi, Federica; Gigliotti, Casimiro Luca; Ciamporcero, Eric Stefano; Daga, Martina; Barrera, Giuseppina

2014-01-01

272

Self-assembled nanoparticles of hydrophobically-modified polysaccharide bearing vitamin H as a targeted anti-cancer drug delivery system  

Microsoft Academic Search

Vitamin H (biotin) was incorporated into a hydrophobically modified polysaccharide, pullulan acetate (PA), in order to improve the cancer-targeting activity and internalization of self-assembled nanoparticles. The biotinylated pullulan acetate (BPA) nanoparticles were prepared by a diafiltration method and the mean diameter was approximately 100 nm. Three samples of biotinylated pullulan acetate (BPA), comprising 7 (BPA 1), 20 (BPA 2), and

Kun Na; Tae Bum Lee; Keun-Hong Park; Eun-Kyung Shin; Yong-Bok Lee; Hoo-Kyun Choi

2003-01-01

273

Externally modulated theranostic nanoparticles  

PubMed Central

Externally modulated nanoparticles comprise a rapidly advancing class of cancer nanotherapeutics, which combine the favorable tumor accumulation of nanoparticles, with external spatio-temporal control on therapy delivery via optical, magnetic, or ultrasound modalities. The local control on therapy enables higher tumor treatment efficacy, while simultaneously reducing off-target effects. The nanoparticle interactions with external fields have an additional advantage of frequently generating an imaging signal, and thus such agents provide theranostic (both diagnostic and therapeutic) capabilities. In this review, we classify the emerging externally modulated theranostic nanoparticles according to the mode of external control and describe the physiochemical mechanisms underlying the external control of therapy, and illustrate the major embodiments of nanoparticles in each class with proven biological efficacy: (I) electromagnetic radiation in visible and near-infrared range is being exploited for gold based and carbon nanostructures with tunable surface plasmon resonance (SPR) for imaging and photothermal therapy (PTT) of cancer, photochemistry based manipulations are employed for light sensitive liposomes and porphyrin based nanoparticles; (II) Magnetic field based manipulations are being developed for iron-oxide based nanostructures for magnetic resonance imaging (MRI) and magnetothermal therapy; (III) ultrasound based methods are primarily being employed to increase delivery of conventional drugs and nanotherapeutics to tumor sites. PMID:24834381

Urban, Cordula; Urban, Alexander S.; Charron, Heather; Joshi, Amit

2013-01-01

274

Synthesis and characterization of photoswitchable fluorescent silica nanoparticles.  

PubMed

We have designed and synthesized a new functional (amino reactive) highly efficient fluorescent molecular switch (FMS) with a photochromic diarylethene and a rhodamine fluorescent dye. The reactive group in this FMS -N-hydroxysuccinimide ester- allows selective labeling of amino containing molecules or other materials. In ethanolic solutions, the compound displays a large fluorescent quantum yield of 52 % and a large fluorescence modulation ratio (94 %) between two states that may be interconverted with red and near-UV light. Silica nanoparticles incorporating the new FMS were prepared and characterized, and their spectroscopic and switching properties were also studied. The dye retained its properties after the incorporation into the silica, thereby allowing light-induced reversible high modulation of the fluorescence signal of a single particle for up to 60 cycles, before undergoing irreversible photobleaching. Some applications of these particles in fluorescence microscopy are also demonstrated. In particular, subdiffraction images of nanoparticles were obtained, in the focal plane of a confocal microscope. PMID:18064615

F闤ling, Jonas; Polyakova, Svetlana; Belov, Vladimir; van Blaaderen, Alfons; Bossi, Mariano L; Hell, Stefan W

2008-01-01

275

Preparation and characterizations of silver incorporated polyurethane composite nanofibers via electrospinning for biomedical applications.  

PubMed

We report on the preparation and characterization of polyurethane (PU) nanofibers containing silver (Ag) nanoparticles were synthesized by using electrospinning. Two different approaches were adopted to incorporate the Ag nanoparticles in to PU nanofibers. In the first approach, a homogeneous solution of 10 wt% PU containing silver nitrate was electrospun to obtain PU-Ag composite nanofibers. And in the second approach, the pristine PU nanofibers were initially electrospun and then Ag nanoparticles were coated via wet casting method. The surface morphology, structure, bonding configuration, optical and thermal properties of the resultant products were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, UV-vis spectroscopy and thermogravimetric analysis. The antibacterial activity was tested against four common food borne pathogenic bacteria, namely, Staphylococcus aureus, Escherichia coli, Salmonella typhimurium and Klebsiella pneumoniae by minimum inhibitory concentration (MIC) method. Our results demonstrated that no bactericidal activity was detected for the pristine PU nanofibers. Further on, antibacterial activity was observed to be more pronounced for the composite nanofibers which were attributed to the presence of Ag nanoparticles in the composite nanofibers. Overall, this study demonstrates the fabrication of cheap, stable and effective nanofiber mats with excellent antimicrobial activity that can be utilized to inhibit the microbial growth associated with food stuff. PMID:23901491

Nirmala, R; Kalpana, Duraisamy; Navamathavan, R; Lee, Yang Soo; Kim, Hak Yong

2013-07-01

276

Hypergolic ionic liquids to mill, suspend, and ignite boron nanoparticles.  

PubMed

Boron nanoparticles prepared by milling in the presence of a hypergolic energetic ionic liquid (EIL) are suspendable in the EIL and the EIL retains hypergolicity leading to the ignition of the boron. This approach allows for incorporation of a variety of nanoscale additives to improve EIL properties, such as energetic density and heat of combustion, while providing stability and safe handling of the nanomaterials. PMID:22446931

McCrary, Parker D; Beasley, Preston A; Cojocaru, O Andreea; Schneider, Stefan; Hawkins, Tommy W; Perez, Jesus Paulo L; McMahon, Brandon W; Pfeil, Mark; Boatz, Jerry A; Anderson, Scott L; Son, Steven F; Rogers, Robin D

2012-05-01

277

New physical effects in layered single crystals with nanoparticles  

Microsoft Academic Search

Layered semiconductors have high anisotropy of chemical bonding. They have strong ion-covalent bonding in separate layers and Van der Waals interaction between neighbouring layers. These semiconductors are considered as intermediate class of substances between 2D- and 3D- solids, between molecular and ion-covalent crystals. Therefore the new phenomena can be observed in physical properties of layered crystals with incorporated nanoparticles. The

F. V. Motsnyi

2008-01-01

278

Formation of magnetite nanoparticles in poly(acrylamide) gels  

Microsoft Academic Search

Magnetic gels with magnetite nanoparticles incorporated in a matrix of poly(acrylamide) gel were studied. Magnetite was synthesized through coprecipitation of Fe(II) and Fe(III) in the gel phase, in the solution of linear polymer and in aqueous solution without polymer in alkaline media. The effects of network structure and of the concentration of iron salts in the swollen networks on the

Sergey G Starodubtsev; Evheniy V Saenko; Maxim E Dokukin; Viktor L Aksenov; Vera V Klechkovskaya; Irina S Zanaveskina; Alexei R Khokhlov

2005-01-01

279

Fluorescence from Coated Oxide Nanoparticles.  

National Technical Information Service (NTIS)

In many cases, coated nanoparticles behave like isolated ones. Using the microwave plasma process, it is possible to produce oxide nanoparticles with ceramic or polymer coating. Coating the particles has the additional advantage that by proper selection o...

D. Vollath, D. V. Szabo, I. Lamparth

2001-01-01

280

MEASUREMENT OF NANOPARTICLES IN WATER  

EPA Science Inventory

Measuring nanoparticles in water differs from traditional dissolved solute measurement in several ways. The most salient difference is that nanoparticles are colloids rather than solutes and therefore are subject to the interparticle interactions (mainly electrostatic and Van de...

281

Nanoparticles for Targeted Drug Delivery  

E-print Network

Nanoparticles were synthesized and modified for target drug delivery. The research involved the aqueous synthesis of near infrared (NIR) sensitive Au-Au2S nanoparticles. An anti-cancer drug (cis-platin) ...

Chow, Gan-Moog

282

Lipoprotein-Inspired Nanoparticles for Cancer Theranostics  

PubMed Central

Over hundreds of millions of years, animals have evolved endogenous lipoprotein nanoparticles for shuttling hydrophobic molecules to different parts of the body. In the last 70 years, scientists have developed an understanding of lipoprotein function, often in relationship to lipid transport and heart disease. Such biocompatible, lipidprotein complexes are also ideal for loading and delivering cancer therapeutic and diagnostic agents, which means that lipoprotein and lipoprotein-inspired nanoparticles also offer opportunities for cancer theranostics. By mimicking the endogenous shape and structure of lipoproteins, the nanocarrier can remain in circulation for an extended period of time, while largely evading the reticuloendothelial cells in the bodys defenses. The small size (less than 30 nm) of the low-density (LDL) and high-density (HDL) classes of lipoproteins allows them to maneuver deeply into tumors. Furthermore, lipoproteins can be targeted to their endogenous receptors, when those are implicated in cancer, or to other cancer receptors. In this Account, we review the field of lipoprotein-inspired nanoparticles related to the delivery of cancer imaging and therapy agents. LDL has innate cancer targeting potential and has been used to incorporate diverse hydrophobic molecules and deliver them to tumors. Natures method of rerouting LDL in atherosclerosis provides a strategy to extend the cancer targeting potential of lipoproteins beyond its narrow purview. Although LDL has shown promise as a drug nanocarrier for cancer imaging and therapy, increasing evidence indicates that HDL, the smallest lipoprotein, may also be of use for drug targeting and uptake into cancer cells. We also discuss how synthetic HDL-like nanoparticles, which do not include human or recombinant proteins, can deliver molecules directly to the cytoplasm of certain cancer cells, effectively bypassing the endosomal compartment. This strategy could allow HDL-like nanoparticles to be used to deliver drugs that have increased activity in the cytoplasm. Lipoprotein nanoparticles have evolved to be ideal delivery vehicles, and because of that specialized function, they have the potential to improve cancer theranostics. PMID:21557543

2011-01-01

283

Automated Morphology Analysis of Nanoparticles  

E-print Network

of the UECS ( = 0:1). : : : : : : : : : : : : : : : : : : 108 1 CHAPTER I INTRODUCTION I.1. Nanoparticles and Their Morphology-related Properties The British and several international standard organizations de ne nanoparticles as ultra ne particles having... only two-dimensional projection images of three-dimensional nanoparticles, they are popularly used in the nanoparticle research because of their ultra-high resolution; the highest resolution is 0.05 nm for TEM or 1 nm for SEM (Allard and O...

Park, Chiwoo

2012-10-19

284

Bioconjugation of colloidal silver nanoparticles  

NASA Astrophysics Data System (ADS)

We have studied bioconjugation of Bovine Serum Albumin (BSA) and DNA with colloidal silver nanoparticles. BSA and DNA modified silver nanoparticles were characterized using UV-Vis spectroscopy and FTIR studies. The emergence of new peaks in UV-Vis spectra corresponding to these biomolecules without shift in surface plasmon peak of silver nanoparticles showed successful modification of metal nanoparticles with BSA and DNA. FTIR spectra also supported these results.

Kaur, Harmandeep; Bhatnagar, Archana; Tripathi, S. K.

2013-06-01

285

Modeling of Au Nanoparticles and Semiconductor Nanowires for Nanodevice Applications  

NASA Astrophysics Data System (ADS)

Semiconductor nanowires with and without plasmon enhancement are being studied for nanodevice applications ranging from chemical sensors to medical monitors and photovoltaics. Semiconductor nanowires can incorporate materials with different bandgaps and can be p- or n-doped. Growths come in different morphologies and geometries (bare, axial or radial heterostructures); all of which expands the design parameters for photocurrent based devices. When Au nanoparticles are attached to nanowires, the local electric field can be enhanced by orders of magnitude, thus increasing their absorption and photocurrent. Using an FDTD Maxwell solver, we simulate local electric fields and absorption characteristics of semiconductor nanowires and Au nanoparticles. We report on spherical, cylindrical and bipyramidal Au nanoparticles with local electric field enhancements that increase with nanoparticle asymmetry and sharp features. The Au nanoparticle modeling data is also in good agreement with experimental absorption data. Initial investigations of 275 nm InP nanowires exhibit internal mode structure under illumination with both polarizations, and absorption coefficients as a function of wavelength. These results provide insight into our experimental investigations of nanowire device applications.

Makepeace, A.; Yarrison-Rice, J. M.; Kumar, P.; Fickenscher, M.; Smith, L. M.; Jackson, H. E.; Choi, Y.-J.; Park, G.-J.; Jagadish, C.

2013-03-01

286

Harmonics based detection of magnetic nanoparticle dynamics for multiparameter biosensing  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles have an increasing role in the clinical and pharmaceutical realms where their physical properties can be exploited for imaging, biological and functional sensing, control of cellular processes, therapeutics, and an array of other applications. When excited by an alternating magnetic field, these particles will produce a series of harmonics. These harmonics have been exploited for in vitro particle detection and for in vivo imaging using magnetic particle imaging (MPI). Using a new technique, which we have termed magnetic spectroscopy of nanoparticle Brownian motion (MSB), we have shown how information about the physical environment of the particles can be extracted from this harmonic spectrum. A variety of physical effects have been detected and/or quantified including temperature, viscosity, nanoparticle binding, and aggregation. Further, we found these different environments to have a unique impact on the spectral signature of the nanoparticles which allows for simultaneous quantification of multiple environmental states. The thesis culminates with a study of MSB as a means for monitoring the cellular uptake of nanoparticles. Potential applications for MSB as a standalone technology and the potential for incorporation into MPI are discussed throughout.

Rauwerdink, Adam M.

287

Nanoparticle release from nano-silver antimicrobial food containers.  

PubMed

Polymer nanocomposites incorporating metal or metal oxide nanoparticles have been developed to improve their characteristics (flexibility, gas barrier properties, antimicrobial or antioxidant properties, etc.). Among them silver nanoparticles are used because of their antimicrobial effect in many daily life materials, i.e. food packaging. However, there is not any reference to the migration of nanoparticles to the food. In this paper the results of migration studies (with different simulant solutions and times) in three commercial nanosilver plastic food containers are shown. Migration solutions were evaluated by ICP-MS and SEM-EDX analysis and silver in dissolved form and silver as nanoparticles were analyzed, a key aspect for the toxicity. Silver migration was observed for all samples studied, with the total silver migration values ranging between 1.66 and 31.46 ng/cm(2) (lower than the permissible limits). Size and morphology of the silver nanoparticles changed for the different samples (ranging between 10 and 60 nm) and migration of other nanosized materials was also confirmed. PMID:23954768

Echegoyen, Yolanda; Ner璯, Cristina

2013-12-01

288

Carbon nanoparticles from laser pyrolysis  

Microsoft Academic Search

Carbon nanoparticles synthesised by laser pyrolysis of hydrocarbons in a flow reactor have been investigated as a function of laser power. Samples are cross-characterised by high resolution transmission electron microscopy (HRTEM) and infrared (IR) spectroscopy. Nanoparticles appear highly aromatic in character in all the experimental conditions explored here. As the flame temperature in the interaction zone increases, the nanoparticles evolve

Aymeric Galvez; Nathalie Herlin-Boime; C嶰ile Reynaud; Christian Clinard; Jean-No螔 Rouzaud

2002-01-01

289

Nano- and microstructures of magnetic field-guided maghemite nanoparticles in diblock copolymer films.  

PubMed

The control over the alignment of nanoparticles within a block copolymer matrix was investigated for different external magnetic fields with respect to producing well-aligned, highly oriented metal-oxide-polymer nanopatterns. Hybrid films were prepared by solution casting under a range of external magnetic fields. The nano- and microstructure of maghemite nanoparticles within poly(styrene-b-methyl methacrylate) diblock copolymer films as a function of the nanoparticle concentration was studied using optical microscopy, atomic force microscopy, scanning electron microscopy, and grazing incidence small-angle X-ray scattering. Because of a polystyrene (PS) coating, the nanoparticles are incorporated in the PS domains of the diblock copolymer morphology. At higher nanoparticle concentrations, nanoparticle aggregates perturb the block copolymer structure and accumulate at the films surface into wire-shaped stripes. These wire-shaped nanoparticle aggregates form mainly because of the competition between nanoparticle-polymer friction and magnetic dipolar interaction. The magnetic behavior of the hybrid films was probed at different temperatures for two orthogonal directions (with the line-shaped particle aggregates parallel and perpendicular to the magnetic field). The hybrid film systems show superparamagnetic behavior and remarkable shape anisotropy that render them interesting for magnetic applications. PMID:24621173

Yao, Yuan; Metwalli, Ezzeldin; Niedermeier, Martin A; Opel, Matthias; Lin, Chen; Ning, Jing; Perlich, Jan; Roth, Stephan V; Mller-Buschbaum, Peter

2014-04-01

290

Molecular-scale interface engineering of metal nanoparticles for plasmon-enhanced dye sensitized solar cells.  

PubMed

A molecular surface chemical treatment is introduced into a dye sensitized solar cell (DSSC) incorporating metal nanoparticles to suppress the charge recombination. Dodecanethiol molecules as a surface treatment agent are successfully anchored onto the exposed Au nanoparticle sites of the ZnO nanorods/Au nanoparticles/N719 photoanode. ATR-FTIR and Raman measurements are conducted to understand the adsorptions of different molecules (dodecanethiol, N719) on the ZnO nanorods and Au nanoparticles surface. The effects of the dodecanethiol surface treatment on the performance of the plasmon-enhanced DSSC are investigated by UV-vis absorption, incident photon-to-current conversion efficiency (IPCE) and electrochemical impedance spectroscopy (EIS). The plasmon-enhanced light absorption due to the presence of Au nanoparticles is not affected by the dodecanethiol surface treatment. The charge recombination on the ZnO nanorods-dye-electrolyte interface is substantially retarded by insulating the exposed Au nanoparticle sites from the oxidized form of the electrolyte via dodecanethiol molecules. The strategy of a molecular surface chemical treatment on the photoanode of a DSSC with metal nanoparticles fully exploits the plasmon-enhanced light absorption and explores a simple method to protect the metal nanoparticles for the plasmon-enhanced DSSC. PMID:23407603

Lou, Yanyan; Yuan, Shuai; Zhao, Yin; Hu, Pengfei; Wang, Zhuyi; Zhang, Meihong; Shi, Liyi; Li, Dongdong

2013-04-21

291

Synthesis of Multifunctional Nanoparticles for Cancer Diagnostics and Therapeutics  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles (MNPs) have attracted enormous research attention due to their unique magnetic properties that enable the detection by the non-invasive medical imaging modality---magnetic resonance imaging (MRI). By incorporating advanced features, such as specific targeting, multimodality, therapeutic delivery, the detectability and applicability of MNPs have been dramatically expanded. Smart and rational design on structure, composition and surface chemistry is essential to achieving desired properties in MNP systems, such as high sensitivity and colloidal stability, target specificity and/or multimodality. The goal of this research is to develop MNP-based platforms for the detection, diagnosis and treatment of cancer. MNPs with high contrast enhancement were coated with poly(ethylene glycol) (PEG)-based polymers to render aqueous stability and confer therapeutic-loading capability. Tumor-specific MNPs were developed by functionalization of nanoparticles with chlorotoxin (CTX) or arginine-glycine-aspartic acid (RGD) that targets, respectively, MMP-2 receptor or alphavbeta3 integrin overexpressed on a variety of cancer cells. The effects of ligands' molecular targets on the temporal and spatial distribution of MNPs within tumors were also investigated both in vitro and in vivo. All MNPs exhibited excellent long-term stability in cell culture media. CTX-labeled MNP exhibited sustained accumulation, penetration and distribution in the tumor mass. These findings revealed the influence of the targeting ligands on the intratumoral distribution of the ligand-enabled nanoprobes. To demonstrate the ability of nanoparticles as drug carrier, anthracyline chemotherapeutic drugs doxorubicin and mitoxantrone were attached to iron oxide nanoparticles. The theragnostic nanoparticles showed sufficient contrast enhancement and comparable anti-neoplastic efficacy in vitro. With flexible surface chemistry, our nanoparticle platform can be used in a modular fashion to conjugate biomolecules for intended applications, and the functionalized nanoparticle systems retain a prolonged stability and exhibit high tumor specificity. The study would establish the foundation for future development of integrated theragnostic systems for the treatment of cancer and other complex diseases.

Fang, Chen

292

Gold Nanoparticles Cytotoxicity  

NASA Astrophysics Data System (ADS)

Over the last two decades gold nanoparticles (AuNPs) have been used for many scientific applications and have attracted attention due to the specific chemical, electronic and optical size dependent properties that make them very promising agents in many fields such as medicine, imagine techniques and electronics. More specifically, biocompatible gold nanoparticles have a huge potential for use as the contrast augmentation agent in X-ray Computed Tomography and Photo Acoustic Tomography for early tumor diagnostic as well these nanoparticles are extensively researched for enhancing the targeted cancer treatment effectiveness such as photo-thermal and radiotherapy. In most biomedical applications biocompatible gold nanoparticles are labeled with specific tumor or other pathology targeting antibodies and used for site specific drug delivery. However, even though gold nanoparticles poses very high level of anti cancer properties, the question of their cytotoxicity ones they are released in normal tissue has to be researched. Moreover, the huge amount of industrially produced gold nanoparticles raises the question of these particles being a health hazard, since the penetration is fairly easy for the "nano" size substances. This study focuses on the effect of AuNPs on a human skin tissue, since it is fall in both categories -- the side effects for biomedical applications and industrial workers and users' exposure during production and handling. Therefore, in the present project, gold nanoparticles stabilized with the biocompatible agent citric acid were generated and characterized by Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM). The cytotoxic effect of AuNPs release to healthy skin tissue was modeled on 3 different cell types: human keratinocytes, human dermal fibroblasts, and human adipose derived stromal (ADS) cells. The AuNPs localization inside the cell was found to be cell type dependent. Overall cytotoxicity was found to be dependent on time, concentration and nanoparticle size. Additionally, the question of cell recovery once the source of AuNPs is removed was investigated in the present work. It was found that full cell functions recovery is possible after removing the source of nanoparticles.

Mironava, Tatsiana

293

Novel light emissive yttrium-based nanoparticles and composites  

NASA Astrophysics Data System (ADS)

Yttrium-based inorganic optical materials generally are of practical interest for three applications: solid state lighting/displays, lasers, and scintillators. Solid-state lighting is particularly desirable commercially for its efficiency and lifetime compared to traditional incandescent alternatives. This type of lighting technology is of increasing interest as incandescent light bulbs are being gradually phased-out due to government regulations on maximum wattage of these devices. Additionally, shortcomings in the current state of the art have driven the need for a more thermally stable material for use in this area. In this dissertation, we develop and characterize a novel composite material consisting of optically active yttrium-based nanoparticles doped into silica sol-gels. For lighting and display applications, low-cost, low-temperature synthesis methods for materials that meet or exceed the quality of the materials currently on the market are highly desirable. During the course of this work, we discuss the characterization of yttrium-based nanoparticles with respect to their incorporation in a sol-gel matrix composite. We then prepared these composite materials using a variety of methods and assess their quality according to a set of selection criteria and for lighting/display applications. Novel light-emitting composites consisting of Ce:YAG or Eu:Y2O 3 (yttria) nanoparticles in an inorganic medium were successfully developed and characterized. The optical properties of the nanoparticles were maintained when incorporated into the sol-gel medium and were shown to be comparable with the current state of the art. Comparison was made between the nanoparticle emission and the composite emission and, in the case of the Ce:YAG, the CIE coordinates, showing no change between the emission intensities or peak locations. We successfully demonstrated the conversion of fluoride-based particles into Y2O3 during sol-gel processing and demonstrated that no reaction took place between the nanoparticles and the sol-gel medium. Stability of nanoparticles in suspension was overcome through the control of pH during sol-gel synthesis. Through both base- and/or acid-catalysis, we produced optically active nanoparticle doped sol-gel composites containing YAG and Yttria. Our results indicated no detrimental effect on the nanoparticles upon incorporation into the sol-gel matrix; this was demonstrated through XRD, where no silicate phases were observed, through EDX, where we saw no diffusion of yttrium into the sol-gel and no silicon diffusing into the nanoparticles, and through photoluminescence, where emissions were consistent with that of the as-made nanoparticles. These results led us to theorize that the nanoparticles, rather than being bonded to the matrix, are seated in the void space that is prevalent in sol-gel systems. Additionally, these materials are stable at much higher temperatures than current resin-based systems.

Hill, Laura Burka

294

Development of Multifunctional Nanoparticles for Cancer Therapy Applications  

NASA Astrophysics Data System (ADS)

The focus of this thesis is the functionalization and tailoring of nanoparticle surfaces to perform specific objectives in a biological environment. The nanoparticles examined include carbon nanotubes (CNTs), superparamagnetic iron oxide nanoparticles and superparamagnetic iron oxide nanocomposites. The unique nanomaterials have been developed to address continued issues in cancer therapy, including cancer diagnosis and efficient drug delivery. CNT surfaces were modified by plasma polymerization, providing functional groups for conjugation. Luminescent amine labeled quantum dots were fixed to the surface of the CNTs to aid in cancer diagnosis by in vivo imaging. Mice, injected with the quantum dot functionalized carbon nanotubes, were imaged displaying the in vivo imaging capability. In addition, the drug loading and drug release capabilities were examined by incorporating the drug paclitaxel into PLGA-coated CNTs, which showed much higher cytotoxicity to PC-3MM2 human prostate carcinoma cells compared to CNTs without paclitaxel. Paclitaxel was loaded at 112.5 microg/mg of PLGA-coated CNTs. Iron oxide nanocomposites were functionalized with quantum dots for diagnosis applications. Because the nanocomposites contain iron oxide, the nanoparticle provides the opportunity for magnetic hyperthermia, creating a unique material for diagnosis and therapy. Mice, injected with the quantum dot functionalized iron oxide nanocomposites, were imaged displaying the in vivo imaging capability. The magnetic hyperthermic property of the quantum dot functionalized nanocomposites was observed with the attainment of temperatures above 50蚓 during exposure to an alternating magnetic field. Thermoresponsive nanoparticles were prepared by immobilizing a 2 - 3 nm thick phospholipid layer on the surface of superparamagnetic Fe3O 4 nanoparticles via high affinity avidin/biotin interactions. Morphological and physicochemical surface properties were assessed using TEM, confocal laser scanning microscopy, differential scanning calorimetry, and ATR-FTIR. The zeta potential of Fe3O4 colloids in phosphate buffered saline (PBS) decreased from -23.6 to -5.0 mV as a consequence of phospholipid immobilization. Hyperthermia-relevant temperatures greater than 40蚓 were achieved within 10--15 min using a 7-mT magnetic field alternating at a frequency of 1MHz. Loading of the surface-associated phospholipid layer with the hydrophobic dye dansylcadaverine was accomplished at an efficiency of 479 ng/mg Fe3O4. Release of this drug surrogate was temperature-dependent, resulting in a 2.5-fold greater release rate when nanoparticles were exposed to temperatures above the experimentally determined melting temperature of 39.7蚓. In vitro cytotoxicity studies by release of the cytotoxic drug, doxorubicin, from the thermoresponsive nanoparticles was lastly intended. However, colloidal stability became an issue, prompting a thorough review of nanoparticle stabilization. Factors affecting stabilization, including dispersant, the nanoparticle, and the thermoresponsive coating, were characterized by dynamic light scattering and zeta potential. PBS was compared to two dispersants containing lower ionic concentrations, HBSS and HEPES, using the original iron oxide nanoparticles compared to an iron oxide nanocomposite. The nanocomposite in the HEPES buffer displayed the greatest stability with a zeta potential of -30.47 mV and particle size of 155.4 nm. Stabilization of the immobilized phospholipid bilayer was examined with and without incorporation of the cationic lipid stearylamine. Zeta potential (33.6 mV) and size (315 nm) data indicate that stearylamine incorporated DPPC coated nanoparticles provide better stability.

Huth, Christopher

295

Preparations of bifunctional polymeric beads simultaneously incorporated with fluorescent quantum dots and magnetic nanocrystals  

NASA Astrophysics Data System (ADS)

Bifunctional polystyrene beads simultaneously incorporated with fluorescent CdTe quantum dots (Q-dots) and superparamagnetic Fe3O4 nanocrystals were prepared by a modified mini-emulsion polymerization method, in which polymerizable surfactants were used as both phase transfer agent for aqueous colloidal nanoparticles and emulsifier. In addition, silica coating was also introduced to Fe3O4 nanocrystals for regulating the internal structure of the composite beads. Transmission electron microscopy, confocal fluorescence microscopy and conventional spectroscopy were used to characterize the composite beads, as well as the polymerizable surfactant-coated CdTe Q-dots and silica-coated Fe3O4 nanoparticles. Different mixing methods were also attempted in order to vary the size of the resultant bifunctional beads.

Tu, Chifeng; Yang, Yunhua; Gao, Mingyuan

2008-03-01

296

Optical properties of free-standing gelatin-Si nanoparticle composite films and gelatin-Si-Au nanoparticle composite films.  

PubMed

A free-standing fluorescent gelatin-Si nanoparticle composite thin film is facilely prepared by means of a filtration technique assisted by porous copper hydroxide nanostrands as a sacrificial layer. The as-prepared gelatin-Si nanoparticle composite film is greatly portable, flexible, transparent and free-standing. The most important advantage is its robust storage stability stored in ambient air, which make it promising for various applications. Meanwhile, a gelatin-Si-Au nanoparticle composite film is also successfully prepared by the formation of Au NPs in a gelatin-Si nanoparticle composite film through the in situ reduction of HAuCl4 at room temperature. The photoluminescence (PL) quenching and blue shift in the peak of the emission spectra occur due to the energy transfer from Si NPs to Au NPs. By varying the amount and size of Au NPs incorporated into the gelatin-Si nanoparticle composite film, the energy transfer efficiency can be controlled. This is a general method to prepare metal-semiconductor hybrid fluorescent nanomaterials, which offers the possibility of tuning the luminescence intensity and wavelength of the emitted light. PMID:24158512

Shi, Li; Yu, Ting; Sun, Luwei; Pi, Xiaodong; Peng, Xinsheng

2013-12-14

297

Incorporating Ethics into K-12 STEM Education  

E-print Network

Incorporating Ethics into K-12 STEM Education: An Introduction Richard A. Burgess, M.A. Texas Tech for Engineering Ethics (NIEE) to incorporate Ethics into all STEM education and outreach efforts. 繚 In this module be integrated into a Project Based Learning (PBL) context. #12;Why Include Ethics in STEM Education? 繚 A great

Gelfond, Michael

298

Potential incorporation of transuranics into uranium phases  

Microsoft Academic Search

The UO in spent nuclear fuel is unstable under moist oxidizing conditions and will be altered to uranyl oxide hydrate phases. The transuranics released during the corrosion of spent fuel may also be incorporated into the structures of secondary U{sup 6+} phases. The incorporation of radionuclides into alteration products will affect their mobility. A series of precipitation tests were conducted

C. W. Kim; D. J. Wronkiewicz; E. C. Buck

1999-01-01

299

Incorporating Sociology into Community Service Classes  

ERIC Educational Resources Information Center

Sociologists and instructors who teach about community service share an affinity for understanding and addressing social problems. While many studies have demonstrated the benefits of incorporating community service into sociology courses, we examine the benefits of incorporating sociological content into community service classes. The authors

Hochschild, Thomas R., Jr.; Farley, Matthew; Chee, Vanessa

2014-01-01

300

Constraints on Noun Incorporation in Korean.  

ERIC Educational Resources Information Center

A study of the noun incorporation phenomenon in Korean suggests that noun incorporation occurs at D-structure and obeys the Head Movement Constraint syntactically, and the Theme-Only Constraint semantically. First, the structure of "sunrise"-type words is identified, showing that before derivation through nominalization of the affix "-i,"

Khym, Hangyoo

1997-01-01

301

Electron beam manipulation of nanoparticles.  

PubMed

We report on electron beam manipulation and simultaneous transmission electron microscopy imaging of gold nanoparticle movements in an environmental cell. Nanoparticles are trapped with the beam and move dynamically toward the location with higher electron density. Their global movements follow the beam positions. Analysis on the trajectories of nanoparticle movements inside the beam reveals a trapping force in the piconewton range at the electron density gradient of 10(3)-10(4) (e搖m(-2)新(-1))搖m(-1). Multiple nanoparticles can also be trapped with the beam. By rapidly converging the beam, we further can "collect" nanoparticles on the membrane surface and assemble them into a cluster. PMID:23035740

Zheng, Haimei; Mirsaidov, Utkur M; Wang, Lin-Wang; Matsudaira, Paul

2012-11-14

302

Nanoparticle shuttle memory  

DOEpatents

A device for storing data using nanoparticle shuttle memory having a nanotube. The nanotube has a first end and a second end. A first electrode is electrically connected to the first end of the nanotube. A second electrode is electrically connected to the second end of the nanotube. The nanotube has an enclosed nanoparticle shuttle. A switched voltage source is electrically connected to the first electrode and the second electrode, whereby a voltage may be controllably applied across the nanotube. A resistance meter is also connected to the first electrode and the second electrode, whereby the electrical resistance across the nanotube can be determined.

Zettl, Alex Karlwalter (Kensington, CA)

2012-03-06

303

Nanoparticles from renewable polymers  

PubMed Central

The use of polymers from natural resources can bring many benefits for novel polymeric nanoparticle systems. Such polymers have a variety of beneficial properties such as biodegradability and biocompatibility, they are readily available on large scale and at low cost. As the amount of fossil fuels decrease, their application becomes more interesting even if characterization is in many cases more challenging due to structural complexity, either by broad distribution of their molecular weights (polysaccharides, polyesters, lignin) or by complex structure (proteins, lignin). This review summarizes different sources and methods for the preparation of biopolymer-based nanoparticle systems for various applications. PMID:25101259

Wurm, Frederik R.; Weiss, Clemens K.

2014-01-01

304

Nanoparticles from renewable polymers.  

PubMed

The use of polymers from natural resources can bring many benefits for novel polymeric nanoparticle systems. Such polymers have a variety of beneficial properties such as biodegradability and biocompatibility, they are readily available on large scale and at low cost. As the amount of fossil fuels decrease, their application becomes more interesting even if characterization is in many cases more challenging due to structural complexity, either by broad distribution of their molecular weights (polysaccharides, polyesters, lignin) or by complex structure (proteins, lignin). This review summarizes different sources and methods for the preparation of biopolymer-based nanoparticle systems for various applications. PMID:25101259

Wurm, Frederik R; Weiss, Clemens K

2014-01-01

305

Nanoparticles: pharmacological and toxicological significance  

PubMed Central

Nanoparticles are tiny materials (<1000 nm in size) that have specific physicochemical properties different to bulk materials of the same composition and such properties make them very attractive for commercial and medical development. However, nanoparticles can act on living cells at the nanolevel resulting not only in biologically desirable, but also in undesirable effects. In contrast to many efforts aimed at exploiting desirable properties of nanoparticles for medicine, there are limited attempts to evaluate potentially undesirable effects of these particles when administered intentionally for medical purposes. Therefore, there is a pressing need for careful consideration of benefits and side effects of the use of nanoparticles in medicine. This review article aims at providing a balanced update of these exciting pharmacological and potentially toxicological developments. The classes of nanoparticles, the current status of nanoparticle use in pharmacology and therapeutics, the demonstrated and potential toxicity of nanoparticles will be discussed. PMID:17245366

Medina, C; Santos-Martinez, M J; Radomski, A; Corrigan, O I; Radomski, M W

2007-01-01

306

Thermally stable nanoparticles on supports  

DOEpatents

An inverse micelle-based method for forming nanoparticles on supports includes dissolving a polymeric material in a solvent to provide a micelle solution. A nanoparticle source is dissolved in the micelle solution. A plurality of micelles having a nanoparticle in their core and an outer polymeric coating layer are formed in the micelle solution. The micelles are applied to a support. The polymeric coating layer is then removed from the micelles to expose the nanoparticles. A supported catalyst includes a nanocrystalline powder, thin film, or single crystal support. Metal nanoparticles having a median size from 0.5 nm to 25 nm, a size distribution having a standard deviation .ltoreq.0.1 of their median size are on or embedded in the support. The plurality of metal nanoparticles are dispersed and in a periodic arrangement. The metal nanoparticles maintain their periodic arrangement and size distribution following heat treatments of at least 1,000.degree. C.

Roldan Cuenya, Beatriz; Naitabdi, Ahmed R.; Behafarid, Farzad

2012-11-13

307

Structural properties of rutile TiO2 nanoparticles accumulated in a model of gastrointestinal epithelium elucidated by micro-beam x-ray absorption fine structure spectroscopy  

NASA Astrophysics Data System (ADS)

Micro-beam x-ray absorption fine structure spectroscopy was used to investigate rutile TiO2 nanoparticles internalized into gastrointestinal cells during their crossing of a gut model barrier. Nanoparticles diluted in culture medium tend to accumulate in cells after 48 h exposure; however, no spectral differences arise between particles in cellular and in acellular environments, as corroborated by quantitative analysis. This finding establishes that no modification of the lattice properties of the nanoparticles occurs upon interaction with the barrier. These measurements demonstrate the possibility of interrogating nanoparticles in situ within cells, suggesting a way to investigate their fate when incorporated in biological hosts.

Veronesi, G.; Brun, E.; Fayard, B.; Cotte, M.; Carri鋨e, M.

2012-05-01

308

Chitosan-lignosulfonates sono-chemically prepared nanoparticles: characterisation and potential applications.  

PubMed

Due to their recognised properties of biocompatibility, biodegradability and sustainability, chitosan nanocarriers have been successfully used as new delivery systems. In this work, nanoparticles combining chitosan and lignosulfonates were developed for the first time for cosmetic and biomedical applications. The ability of lignosulfonates to act as a counter polyion for stabilisation of chitosan particles, generated using high intensity ultrasound, was investigated. Several conditions for particles preparation were tested and optimised and the resulting nanoparticles were comprehensively characterised by measuring particle size, zeta potential and polydispersity index. The pH of chitosan solution, sonication time and the presence of an adequate surfactant, poloxamer 407, were determinant factors on the development of smaller particles with low polydispersity index (an average particle size of 230 nm was obtained at pH 5 after 8 min of sonication). The beneficial effects of lignosulfonates complex on chitosan nanoparticles were further characterised. Greater stability to lysozyme degradation, biocompatibility with human cells and antimicrobial activity was found upon lignosulfonates incorporation into chitosan nanoparticles. Furthermore, these particles were able to incorporate a hydrophilic model protein - RNase A. A burst release was observed when nanoparticles were loaded with low amount of protein while with high protein content, a sustained release was found, suggesting that the protein cargo maybe loaded both at the surface as in the bulk of the particle, depending on the concentration of drug incorporated. PMID:23178385

Kim, Suyeon; Fernandes, Margarida M; Matam, Teresa; Loureiro, Ana; Gomes, Andreia C; Cavaco-Paulo, Artur

2013-03-01

309

Enzyme Nanoparticles-Based Electronic Biosensor  

Microsoft Academic Search

A novel method for fabricating electronic biosensors based on coupling enzyme nanoparticles and self assembly technology is illustrated. Redox horseradish peroxidase nanoparticles were prepared by desolvation with ethanol and subsequent crosslinking with glutaraldehyde. The cross-linked enzyme nanoparticles were functionalized by cysteine to introduce thiol groups on the nanoparticle surface. Immobilized enzyme nanoparticle on the gold electrode by self-assembly kept redox

Guodong Liu; Yuehe Lin; V. Ostatna; Joseph Wang

2005-01-01

310

YAG:Ce nanoparticle based converter layer for white LEDs  

NASA Astrophysics Data System (ADS)

Our work is devoted to the development of YAG:Ce3+ nanoparticle based films for white LEDs. Very stable suspensions of YAG:Ce nanoparticles are synthesized by a glycothermal method at relatively low temperature (300蚓). A protected annealing in a silica matrix allows further treatment of these nanoparticles at high temperature without any aggregation and growth and with a significant improvement of their quantum yield and photostability. The obtained colloidal nanoparticles are finally incorporated into different matrices to be used as converter layer for white LEDs. First, the incorporation in epoxy caps confirms that the annealed particles are much more efficient than the as-made ones and leads to white light generation. YAG:Ce nanoparticles are also dispersed into a sol-gel matrix of TiO2. Thanks to the relative matching of refractive indexes between TiO2 and YAG, and to the sub-wavelength particles size, YAG/TiO2films are not scattering, contrary to the same film containing the commonly used micron size phosphor. Nevertheless, they are not absorbent enough. Thus, YAG:Ce suspensions are then spray-coated to obtain thicker and non diluted films. These films are a bit scattering but this can be solved by filling their porosity with a high refractive index matrix. A yellow component is detected when deposited onto a blue LED, meaning that they absorb much more than the YAG:Ce/TiO2 system. When used as light converters for white LEDs, these spray-coated films could offer the opportunity to diminish the backscattered light absorption losses.

Revaux, Amelie; Dantelle, Geraldine; Brinkley, Stewart; Matioli, Elison; Weisbuch, Claude; Boilot, Jean-Pierre; Gacoin, Thierry

2011-10-01

311

Antigen incorporation on Cryptosporidium parvum oocyst walls.  

PubMed

Cryptosporidium parvum oocysts are the infective stages responsible for transmission and survival of the organism in the environment. In the present work we show that the oocyst wall, far from being a static structure, is able to incorporate antigens by a mechanism involving vesicle fusion with the wall, and the incorporation of the antigen to the outer oocyst wall. Using immunoelectron microscopy we show that the antigen recognized by a monoclonal antibody used for diagnosis of cryptosporidiosis (Merifluor(R), Meridian Diagnostic Inc.) could be found associated with vesicles in the space between the sporozoites and the oocysts wall, and incorporated to the outer oocyst wall by an unknown mechanism. PMID:11285502

Entrala, E; Sbihi, Y; S嫕chez-Moreno, M; Mascar, C

2001-02-01

312

Arsenic incorporation in a salt marsh ecosystem  

NASA Astrophysics Data System (ADS)

Replicate portions of a Delaware salt marsh were enclosed in cylindrical microcosms and exposed to elevated levels of inorganic arsenic (arsenate). All biotic and abiotic components in dosed cylinders rapidly incorporated arsenic. Spartina blades showed the greatest arsenic enrichment, with dosed plants incorporating arsenic concentrations an order of magnitude higher than controls. Spartina detritus and sediments also exhibited greatly elevated arsenic concentrations. Virtually all of the arsenic was incorporated into plant tissue or strongly sorbed to cell surfaces. Thus, elevated arsenic concentrations in estuarine waters will be reflected in living and non-living components of a salt marsh ecosystem, implying that increased arsenic will be available to organisms within the marsh ecosystem.

Sanders, James G.; Osman, Richard W.

1985-04-01

313

Nanoparticles as biochemical sensors  

PubMed Central

There is little doubt that nanoparticles offer real and new opportunities in many fields, such as biomedicine and materials science. Such particles are small enough to enter almost all areas of the body, including cells and organelles, potentially leading to new approaches in nanomedicine. Sensors for small molecules of biochemical interest are of critical importance. This review is an attempt to trace the use of nanomaterials in biochemical sensor design. The possibility of using nanoparticles functionalized with antibodies as markers for proteins will be elucidated. Moreover, capabilities and applications for nanoparticles based on gold, silver, magnetic, and semiconductor materials (quantum dots), used in optical (absorbance, luminescence, surface enhanced Raman spectroscopy, surface plasmon resonance), electrochemical, and mass-sensitive sensors will be highlighted. The unique ability of nanosensors to improve the analysis of biochemical fluids is discussed either through considering the use of nanoparticles for in vitro molecular diagnosis, or in the biological/biochemical analysis for in vivo interaction with the human body. PMID:24198472

El-Ansary, Afaf; Faddah, Layla M

2010-01-01

314

Engineering Pharmaceutical Nanoparticles  

E-print Network

Engineering Pharmaceutical Nanoparticles Cory Berkland Assistant Professor Department of Pharmaceutical Chemistry Assistant Professor Department of Chemical and Petroleum Engineering The University of Kansas 2 Acknowledgements Postdocs: David Shi... enough to enter cells. Particle size >200 nm enables intracellular delivery. www.genovis.com 6 Particle engineering is critical for pharmaceutical applications. ? Dissolution rate #0;z Control size ? Pulmonary delivery #0;z ~3 microns ? Nasal...

Berkland, Cory

2006-10-26

315

Traveling Nanoparticles Model  

NSDL National Science Digital Library

This is an activity (located on page 3 of the PDF) about diffusion of small molecules across cell membranes. Learners will use gelatin to represent a cell and dye to represent molecules to model how small molecules such as nanoparticles can penetrate living environments. Relates to linked video, DragonflyTV: Nanosilver.

Forbes, Neil; Twin Cities Public Television, Inc.

2008-01-01

316

Synthesis of fluorine-18 functionalized nanoparticles for use as in vivo molecular imaging agents.  

PubMed

Nanoparticles containing fluorine-18 were prepared from block copolymers made by ring opening metathesis polymerization (ROMP). Using the fast initiating ruthenium metathesis catalyst (H2IMes)(pyr)2(Cl)2Ru=CHPh, low polydispersity amphiphilic block copolymers were prepared from a cinnamoyl-containing hydrophobic norbornene monomer and a mesyl-terminated PEG-containing hydrophilic norbornene monomer. Self-assembly into micelles and subsequent cross-linking of the micelle cores by light-activated dimerization of the cinnamoyl groups yielded stable nanoparticles. Incorporation of fluorine-18 was achieved by nucleophilic displacement of the mesylates by the radioactive fluoride ion with 31% incorporation of radioactivity. The resulting positron-emitting nanoparticles are to be used as in vivo molecular imaging agents for use in tumor imaging. PMID:18452296

Matson, John B; Grubbs, Robert H

2008-05-28

317

Synthesis of Fluorine-18 Functionalized Nanoparticles for Use as in Vivo Molecular Imaging Agents  

NASA Astrophysics Data System (ADS)

Nanoparticles containing fluorine-18 were prepared from block co-polymers made by ring-opening metathesis polymerization (ROMP). Using the fast initiating ruthenium metathesis catalyst (H2IMes)(pyr)2(Cl)2RuCHPh, narrow polydispersity, amphiphilic block copolymers were prepared from a cinnamoyl-containing, hydrophobic norbornene monomer and a mesylate-terminated, PEG-containing hydrophilic norbornene monomer. Self-assembly into micelles and subsequent crosslinking of the micelle cores by light-activated dimerization of the cinnamoyl groups yielded stable nanoparticles. Incorporation of fluorine-18 was achieved by nucleophilic displacement of the mesylates with the radioactive fluoride ion with 31% incorporation of radioactivity. The resulting positron-emitting nanoparticles are to be used as in vivo molecular imaging agents in tumor imaging.

Matson, John B.; Grubbs, Robert H.

318

Interplay of hydrogen treatment and nitrogen doping in ZnO nanoparticles: a first-principles study  

NASA Astrophysics Data System (ADS)

With the help of density functional calculations using the HSE and PBE functionals, it is shown that incorporation of nitrogen into ZnO nanoparticles is energetically less costly compared to ZnO bulk, due to charge transfer between Zn dangling bonds and the NO impurity. Neutral NO results after full passivation of the doped nanoparticles by a treatment with atomic hydrogen. A nanocomposite made from such ZnO particles could show thermally activated p-type hopping conductivity.

Gutjahr, Johann; Sakong, Sung; Kratzer, Peter

2014-04-01

319

Study on the friction and wear properties of carbon fabric composites reinforced with micro- and nano-particles  

Microsoft Academic Search

The carbon fabric composites filled with the particulates of polyfluo-150 wax (PFW), nano-particles of ZnO (nano-ZnO), and nano-particles of SiC (nano-SiC), respectively, were prepared by dip-coating of the carbon fabric in a phenolic resin containing the particulates to be incorporated and the successive curing. The friction and wear behaviors of the carbon fabric composites sliding against AISI-1045 steel in a

Zhao-Zhu Zhang; Feng-Hua Su; Kun Wang; Wei Jiang; Xue-hu Men; Wei-Min Liu

2005-01-01

320

Development of cellulose-based bactericidal nanocomposites containing silver nanoparticles and their use as active food packaging  

Microsoft Academic Search

The use of nanomaterials, including metallic as active fillers in polymeric nanocomposites for food packaging has been extensively investigated. Silver nanoparticles (AgNPs), in particular, have been exploited for technological applications as bactericidal agents. In this paper, AgNPs were incorporated into a hydroxypropyl methylcellulose (HPMC) matrix for applications as food packaging materials. The average sizes of the silver nanoparticles were 41nm

M嫫cia R. de Moura; Luiz H. C. Mattoso; Valtencir Zucolotto

321

Aerodynamic Focusing of Nanoparticles: II. Numerical Simulation of Particle Motion Through Aerodynamic Lenses  

Microsoft Academic Search

We have developed a numerical simulation methodology that is able to accurately characterize the focusing performance of aerodynamic lens systems. The commercial computational fluid dynamics (CFD) software FLUENT was used to simulate the gas flow field. Particle trajectories were tracked using the Lagrangian approach. Brownian motion of nanoparticles was successfully incorporated in our numerical simulations. This simulation tool was then

Xiaoliang Wang; Ashok Gidwani; Steven L. Girshick; Peter H. McMurry

2005-01-01

322

Dextran-b-poly(L-histidine) copolymer nanoparticles for ph-responsive drug delivery to tumor cells  

PubMed Central

Purpose Nanoparticles based on stimuli-sensitive drug delivery have been extensively investigated for tumor targeting. Among them, pH-responsive drug targeting using pH-sensitive polymers has attracted attention because solid tumors have an acidic environment. A dextran-b-poly(L-histidine) (DexPHS) copolymer was synthesized and pH-responsive nanoparticles were fabricated for drug targeting. Methods and results A DexPHS block copolymer was synthesized by attaching the reductive end of dextran to the amine groups of poly(L-histidine). pH-responsive nanoparticles incorporating doxorubicin were fabricated and studied in HuCC-T1 cholangiocarcinoma cells. Synthesis of DexPHS was confirmed by 1H nuclear magnetic resonance spectroscopy, with specific peaks of dextran and PHS observed at 25 ppm and 7.49.0 ppm, respectively. DexPHS nanoparticles showed changes in particle size with pH sensitivity, ie, the size of the nanoparticles increased at an acidic pH and decreased at a basic pH. DexPHS block copolymer nanoparticles incorporating doxorubicin were prepared using the nanoprecipitation dialysis method. The doxorubicin release rate was increased at acidic pH compared with basic pH, indicating that DexPHS nanoparticles have pH-sensitive properties and that drug release can be controlled by variations in pH. The antitumor activity of DexPHS nanoparticles incorporating doxorubicin were studied using HuCC-T1 cholangiocarcinoma cells. Viability was decreased in cells treated with nanoparticles at acidic pH, whereas cell viability in response to treatment with doxorubicin did not vary according to changes of pH. Conclusion Our results indicated that DexPHS polymeric micelles are promising candidates for antitumor drug targeting. PMID:23986636

Hwang, Jong-ho; Choi, Cheol Woong; Kim, Hyung-Wook; Kim, Do Hyung; Kwak, Tae Won; Lee, Hye Myeong; Kim, Cy hyun; Chung, Chung Wook; Jeong, Young-II; Kang, Dae Hwan

2013-01-01

323

49 CFR 572.30 - Incorporated materials.  

Code of Federal Regulations, 2011 CFR

...NATIONAL HIGHWAY TRAFFIC SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) ANTHROPOMORPHIC TEST DEVICES Hybrid III Test Dummy 572.30 Incorporated materials. (a) The drawings and specifications referred to in this...

2011-10-01

324

In vivo [35S]-methionine incorporation.  

PubMed

The purpose of this assay is to measure the incorporation of radiolabeled [(35)S]-methionine into newly synthesized proteins in exponentially growing yeast cells. This allows for a quantitative in vivo measurement of total protein synthesis. PMID:24423266

Esposito, Anthony M; Kinzy, Terri Goss

2014-01-01

325

Concept Sciences, Incorporated, Hanover Township, Pennsylvania.  

National Technical Information Service (NTIS)

On Friday, February 19, 1999, a devastating explosion destroyed a plant operated by Concept Sciences, Incorporated (CSI) in Hanover Township, Pennsylvania. The blast killed five people and caused approximately $5 million in damages. Fourteen people, inclu...

J. L. Cook

1999-01-01

326

Lattice-patterned LC-polymer composites containing various nanoparticles as additives  

PubMed Central

In this study, we show the effect of various nanoparticle additives on phase separation behavior of a lattice-patterned liquid crystal [LC]-polymer composite system and on interfacial properties between the LC and polymer. Lattice-patterned LC-polymer composites were fabricated by exposing to UV light a mixture of a prepolymer, an LC, and SiO2 nanoparticles positioned under a patterned photomask. This resulted in the formation of an LC and prepolymer region through phase separation. We found that the incorporation of SiO2 nanoparticles significantly affected the electro-optical properties of the lattice-patterned LC-polymer composites. This effect is a fundamental characteristic of flexible displays. The electro-optical properties depend on the size and surface functional groups of the SiO2 nanoparticles. Compared with untreated pristine SiO2 nanoparticles, which adversely affect the performance of LC molecules surrounded by polymer walls, SiO2 nanoparticles with surface functional groups were found to improve the electro-optical properties of the lattice-patterned LC-polymer composites by increasing the quantity of SiO2 nanoparticles. The surface functional groups of the SiO2 nanoparticles were closely related to the distribution of SiO2 nanoparticles in the LC-polymer composites, and they influenced the electro-optical properties of the LC molecules. It is clear from our work that the introduction of nanoparticles into a lattice-patterned LC-polymer composite provides a method for controlling and improving the composite's electro-optical properties. This technique can be used to produce flexible substrates for various flexible electronic devices. PMID:22222011

2012-01-01

327

Enhancement of the fluorescence of triphenylmethane dyes caused by their interaction with nanoparticles from ?-diketonate complexes  

NASA Astrophysics Data System (ADS)

We have studied the absorption and fluorescence spectra of Malachite Green and Crystal Violet in aqueous and alcoholic-aqueous solutions in which nanoparticles from Ln(III) and Sc(III) diketonates are formed at concentrations of complexes in a solution of 5-30 ?M. We have shown that, if the concentrations of the dyes in the solution are lower than 0.5 ?M, dye molecules are incorporated completely into nanoparticles or are precipitated onto their surface. The fluorescence intensity of these incorporated and adsorbed Malachite Green and Crystal Violet molecules increases by several orders of magnitude compared to the solution, which takes place because of a sharp increase in the fluorescence quantum yields of these dyes and at the expense of the sensitization of their fluorescence upon energy transfer from ?-diketonate complexes entering into the composition of nanoparticles. We have shown that, if there is no concentration quenching, the values of the fluorescence quantum yield of the Crystal Violet dye incorporated into nanoparticles and adsorbed on their surface vary from 0.06 to 0.13, i.e., are close to the fluorescence quantum yield of this dye in solid solutions of sucrose acetate at room temperature. The independence of the fluorescence quantum yield of Crystal Violet on the morphology of nanoparticles testifies to a high binding constant of complexes and the dye. The considerable fluorescence quantum yields of triphenylmethane dyes in nanoparticles and sensitization of their fluorescence by nanoparticle-forming complexes make it possible to determine the concentration of these dyes in aqueous solutions by the luminescent method in the range of up to 1 nM.

Sveshnikova, E. B.; Ermolaev, V. L.

2014-08-01

328

LDRD Progress Report: Radioimmunotherapy using oxide nanoparticles: Radionuclide contaiment and mitigation of normal tissue toxicity.  

SciTech Connect

Radionuclides with specific emission properties can be incorporated into metal-chalcogenide and metal-oxide nanoparticles. Coupled to antibodies, these conjugates could be injected into the bloodstream to target and destroy non-solid tumors or target organs for radioimaging. In the first year of this project, two types of radioactive nanoparticles, CdTe: {sup 125m}Te and Y{sub 2}O{sub 3}: {sup 170}Tm were synthesized and coupled to antibodies specific to murine epithelial lung tissue. The nanoparticles successfully target the lung tissue in vivo. Some leaching of the radioisotope was observed. The coming year will explore other types of nanoparticles (other crystal chemistries) in order to minimize leaching.

Rondinone, Adam Justin [ORNL; Dai, Sheng [ORNL; Mirzadeh, Saed [ORNL; Kennel, Steve J [ORNL

2005-10-01

329

Functionalized carbon nanoparticles, blacks and soots as electron-transfer building blocks and conduits.  

PubMed

Functionalized carbon nanoparticles (or blacks) have promise as novel active high-surface-area electrode materials, as conduits for electrons to enzymes or connections through lipid films, or as nano-building blocks in electroanalysis. With previous applications of bare nanoblacks and composites mainly in electrochemical charge storage and as substrates in fuel cell devices, the full range of benefits of bare and functionalized carbon nanoparticles in assemblies and composite (bio)electrodes is still emerging. Carbon nanoparticles are readily surface-modified, functionalized, embedded, or assembled into nanostructures, employed in bioelectrochemical systems, and incorporated into novel electrochemical sensing devices. This focus review summarizes aspects of a rapidly growing field and some of the recent developments in carbon nanoparticle functionalization with potential applications in (bio)electrochemical, photoelectrochemical, and electroanalytical processes. PMID:24616339

Lawrence, Katherine; Baker, Charlotte L; James, Tony D; Bull, Steven D; Lawrence, Ruth; Mitchels, John M; Opallo, Marcin; Arotiba, Omotayo A; Ozoemena, Kenneth I; Marken, Frank

2014-05-01

330

Incorporating game management into the ranching enterprise  

E-print Network

Record of Study INCORPORATING GAME MANAGEMENT INTO THE RANCHING ENTERPRISE A PROFESSIONAL PAPER by MARY JUDITH EAGLESHAM Submitted to the College of Agriculture of Texas A & M University in partial fulfillment of the requirements... for the degree of MASTER OF AGRICULTURE August, 1986 Wildlife Science Department of Wildlife and Fisheries Sciences INCORPORATING GAME MANAGEMENT INTO THE RANCHING ENTERPRISE A Professional Paper by MARY JUDITH EAGLESHAM Approved as to style a Ja . I...

Eaglesham, Mary Judith

2012-06-07

331

A general strategy for the DNA-mediated self-assembly of functional nanoparticles into heterogeneous systems.  

PubMed

Nanoparticles coated with DNA molecules can be programmed to self-assemble into three-dimensional superlattices. Such superlattices can be made from nanoparticles with different functionalities and could potentially exploit the synergetic properties of the nanoscale components. However, the approach has so far been used primarily with single-component systems. Here, we report a general strategy for the creation of heterogeneous nanoparticle superlattices using DNA and carboxylic-based conjugation. We show that nanoparticles with all major types of functionality--plasmonic (gold), magnetic (Fe2O3), catalytic (palladium) and luminescent (CdSe/Te@ZnS and CdSe@ZnS)--can be incorporated into binary systems in a rational manner. We also examine the effect of nanoparticle characteristics (including size, shape, number of DNA per particle and DNA flexibility) on the phase behaviour of the heterosystems, and demonstrate that the assembled materials can have novel optical and field-responsive properties. PMID:24141539

Zhang, Yugang; Lu, Fang; Yager, Kevin G; van der Lelie, Daniel; Gang, Oleg

2013-11-01

332

A general strategy for the DNA-mediated self-assembly of functional nanoparticles into heterogeneous systems  

NASA Astrophysics Data System (ADS)

Nanoparticles coated with DNA molecules can be programmed to self-assemble into three-dimensional superlattices. Such superlattices can be made from nanoparticles with different functionalities and could potentially exploit the synergetic properties of the nanoscale components. However, the approach has so far been used primarily with single-component systems. Here, we report a general strategy for the creation of heterogeneous nanoparticle superlattices using DNA and carboxylic-based conjugation. We show that nanoparticles with all major types of functionality--plasmonic (gold), magnetic (Fe2O3), catalytic (palladium) and luminescent (CdSe/Te@ZnS and CdSe@ZnS)--can be incorporated into binary systems in a rational manner. We also examine the effect of nanoparticle characteristics (including size, shape, number of DNA per particle and DNA flexibility) on the phase behaviour of the heterosystems, and demonstrate that the assembled materials can have novel optical and field-responsive properties.

Zhang, Yugang; Lu, Fang; Yager, Kevin G.; van der Lelie, Daniel; Gang, Oleg

2013-11-01

333

Preparation of bio-compatible boron nanoparticles and novel mesoporous silica nanoparticles for bio-applications  

NASA Astrophysics Data System (ADS)

This dissertation presents the synthesis and characterization of several novel inorganic and hybrid nanoparticles, including the bio-compatible boron nanoparticles (BNPs) for boron neutron capture therapy (BNCT), tannic acid-templated mesoporous silica nanoparticles and degradable bridged silsesquioxane silica nanoparticles. Chapter 1 provides background information of BNCT and reviews the development of design and synthesizing silica nanoparticles and the study of silica material degradability. Chapter 2 describes the preparation and characterization of dopamine modified BNPs and the preliminary cell study of them. The BNPs were first produced via ball milling, with fatty acid on the surface to stabilize the combustible boron elements. This chapter will mainly focus on the ligand-exchange strategy, in which the fatty acids were replaced by non-toxic dopamines in a facile one-pot reaction. The dopamine-coated BNPs (DA-BNPs) revealed good water dispersibility and low cytotoxicity. Chapter 3 describes the synthesis of tannic acid template mesoporous silica nanoparticles (TA-TEOS SiNPs) and their application to immobilize proteins. The monodispersed TA SiNPs with uniform pore size up to approximately 13 nm were produced by utilizing tannic acid as a molecular template. We studied the influence of TA concentration and reaction time on the morphology and pore size of the particles. Furthermore, the TA-TEOS particles could subsequently be modified with amine groups allowing them to be capable of incorporating imaging ligands and other guest molecules. The ability of the TA-TEOS particles to store biomolecules was preliminarily assessed with three proteins of different charge characteristics and dimensions. The immobilization of malic dehydrogenase on TA-TEOS enhanced the stability of the enzyme at room temperature. Chapter 4 details the synthesis of several bridged silsesquioxanes and the preparation of degradable hybrid SiNPs via co-condensation of bridged silsesquioxanes with tetraethoxysilane. In vivo studies show that the solid SiNPs accumulate in many organs due to the lack of degradability. The aim of our work is to address this shortcoming by producing novel degradable SiNPs. Bridged silsesquioxanes were used as the precursors of the particles, and upon cleavage of the carbamate groups when brought into contact with aqueous media, the particles degraded into porous structures.

Gao, Zhe

334

Highly luminescent material based on Alq3:Ag nanoparticles.  

PubMed

Tris (8-hydroxyquinoline) aluminum (Alq3) is an organic semiconductor molecule, widely used as an electron transport layer, light emitting layer in organic light-emitting diodes and a host for fluorescent and phosphorescent dyes. In this work thin films of pure and silver (Ag), cupper (Cu), terbium (Tb) doped Alq3 nanoparticles were synthesized using the physical vapor condensation method. They were fabricated on glass substrates and characterized by X-ray diffraction, scanning electron microscope (SEM), energy dispersive spectroscopy, atomic force microscope (AFM), UV-visible absorption spectra and studied for their photoluminescence (PL) properties. SEM and AFM results show spherical nanoparticles with size around 70-80 nm. These nanoparticles have almost equal sizes and a homogeneous size distribution. The maximum absorption of Alq3 nanoparticles is observed at 300 nm, while the surface plasmon resonant band of Ag doped sample appears at 450 nm. The PL emission spectra of Tb, Cu and Ag doped Alq3 nanoparticles show a single broad band at around 515 nm, which is similar to that of the pure one, but with enhanced PL intensity. The sample doped with Ag at a concentration ratio of Alq3:Ag = 1:0.8 is found to have the highest PL intensity, which is around 2 times stronger than that of the pure one. This enhancement could be attributed to the surface plasmon resonance of Ag ions that might have increased the absorption and then the quantum yield. These remarkable result suggest that Alq3 nanoparticles incorporated with Ag ions might be quite useful for future nano-optoelectronic devices. PMID:23653126

Salah, Numan; Habib, Sami S; Khan, Zishan H

2013-09-01

335

Preparation of ZnO nanoparticles in a reverse micellar system and their photoluminescence properties.  

PubMed

ZnO nanoparticles with spherical morphology and narrow size distribution were obtained by calcination of Zn(OH)2 nanoparticles, which were prepared in a polyethylene glycol mono-4-nonylphenyl ether (NP-5)/cyclohexane reverse micellar system and incorporated into polyurea (PUA) via an in situ polymerization of hexamethylene diisocyanate (HDI). The resulting ZnO nanoparticles demonstrated a near-UV emission and a green emission, the intensity ratio of which depended on calcination conditions. For the nanoparticles studied, the calcination atmosphere influenced remarkably the photoluminescence properties such as intensity ratio of the near-UV emission to green emission, rather than the size, morphology, and crystallinity of the ZnO nanoparticles. The green emission decreased by calcination in O2 flow but increased by calcination in N2 flow, as compared with the case calcined in air flow. This finding suggests that the green emission is enhanced with the increase of the number of oxygen vacancies of the ZnO nanoparticles and thus the photoluminescence properties of the nanoparticles were successfully controlled by the calcination condition, without changing the size and morphology. PMID:15752800

Hirai, Takayuki; Asada, Yoko

2005-04-01

336

Shape-controlled synthesis of NIR absorbing branched gold nanoparticles and morphology stabilization with alkanethiols  

NASA Astrophysics Data System (ADS)

Gold nanoparticles are ideal candidates for clinical applications if their plasmon absorption band is situated in the near infrared region (NIR) of the electromagnetic spectrum. Various parameters, including the nanoparticle shape, strongly influence the position of this absorption band. The aim of this study is to produce stabilized NIR absorbing branched gold nanoparticles with potential for biomedical applications. Hereto, the synthesis procedure for branched gold nanoparticles is optimized varying the different synthesis parameters. By subsequent electroless gold plating the plasmon absorption band is shifted to 747.2 nm. The intrinsic unstable nature of the nanoparticles' morphology can be clearly observed by a spectral shift and limits their use in real applications. However, in this article we show how the stabilization of the branched structure can be successfully achieved by exchanging the initial capping agent for different alkanethiols and disulfides. Furthermore, when using alkanethiols/disulfides with poly(ethylene oxide) units incorporated, an increased stability of the gold nanoparticles is achieved in high salt concentrations up to 1 M and in a cell culture medium. These achievements open a plethora of opportunities for these stabilized branched gold nanoparticles in nanomedicine.

Van de Broek, B.; Frederix, F.; Bonroy, K.; Jans, H.; Jans, K.; Borghs, G.; Maes, G.

2011-01-01

337

Evaluation of antimicrobial activity of silver nanoparticles for carboxymethylcellulose film applications in food packaging.  

PubMed

In this study, silver nanoparticles were prepared and incorporated into carboxymethylcellulose films to evaluate the antimicrobial activity for food packaging applications. The techniques carried out for material characterization were: infrared spectroscopy and thermal analysis for the silver nanoparticles and films, as well as particle size distribution for the nanoparticles and water vapor permeability for the films. The antimicrobial activity of silver nanoparticles prepared by casting method was investigated. The minimum inhibitory concentration (MIC) value of the silver nanoparticles to test Gram-positive (Enterococcus faecalis) and Gram-negative (Escherichia coli) microorganisms was carried out by the serial dilution technique, tested in triplicate to confirm the concentration used. The results were developed using the Mcfarland scale which indicates that the presence or absence of turbidity tube demonstrates the inhibition of bacteria in relation to the substance inoculated. It was found that the silver nanoparticles inhibited the growth of the tested microorganisms. The carboxymethylcellulose film embedded with silver nanoparticles showed the best antimicrobial effect against Gram-positive (E. faecalis) and Gram-negative (E. coli) bacteria (0.1 microg cm(-3)). PMID:24758059

Siqueira, Maria C; Coelho, Gustavo F; de Moura, M嫫cia R; Bresolin, Joana D; Hubinger, Silviane Z; Marconcini, Jos M; Mattoso, Luiz H C

2014-07-01

338

Functionalized Fe3O4@Au superparamagnetic nanoparticles: in vitro bioactivity  

NASA Astrophysics Data System (ADS)

The interaction of nanoparticles with cells has been a focus of interest during the past decade. We report the fabrication and characterization of hydrosoluble Fe3O4@Au nanoparticles functionalized with biocompatible and fluorescent molecules and their interaction with cell cultures by visualizing them with confocal microscopy. Gold covered iron oxide nanoparticles were synthesized by reducing metal salts in the presence of oleylamine and oleic acid. The functionalization of these particles with an amphiphilic polymer provides a water soluble corona as well as the possibility to incorporate different molecules relevant for bio-applications such as poly(ethylene glycol), glucose or a cadaverine derived dye. The particle size, and the presence of polymer layers and conjugated molecules were characterized and confirmed by transmission electron microscopy, thermogravimetric measurements and infrared spectroscopy. A complete magnetic study was performed, showing that gold provides an optimum coating, which enhances the superparamagnetic behaviour observed above 10-15 K in this kind of nanoparticle. The interaction with cells and the cytotoxicity of the Fe3O4@Au preparations were determined upon incubation with the HeLa cell line. These nanoparticles showed no cytotoxicity when evaluated by the MTT assay and it was demonstrated that nanoparticles clearly interacted with the cells, showing a higher level of accumulation in the cells for glucose conjugated nanoparticles.

Salado, J.; Insausti, M.; Lezama, L.; Gil de Muro, I.; Moros, M.; Pelaz, B.; Grazu, V.; de la Fuente, J. M.; Rojo, T.

2012-08-01

339

Crosslinked chitosan nanoparticle formulations for delivery from pressurized metered dose inhalers.  

PubMed

Crosslinked chitosan nanoparticles, prepared using ionic gelation, have been successfully formulated into pressurized metered dose inhalers (pMDIs) with potential for deep lung delivery of therapeutic agents. Nanoparticles were prepared from crosslinked chitosan alone and incorporating PEG 600, PEG 1000 and PEG 5000 for dispersion in aerosol propellant, hydrofuoroalkane (HFA) 227. Spherical, smooth-surfaced, cationic particles of mean size less than 230 nm were produced. Nanoparticles were positively charged and non-aggregated at the pH of the airways. Crosslinked chitosan-PEG 1000 nanoparticles demonstrated greatest dispersibility and physical stability in HFA-227, whereas other formulations readily either creamed or sedimented. Following actuation from pMDIs, the fine particle fraction (FPF) for crosslinked chitosan-PEG 1000 nanoparticles, determined using a next generation impactor, was 34.01.4% with a mass median aerodynamic diameter of 4.920.3 ?m. The FPFs of crosslinked chitosan, crosslinked chitosan-PEG 600 and crosslinked chitosan-PEG 5000 nanoparticles were 5.70.9%, 11.82.7% and 17.02.1%, respectively. These results indicate that crosslinked chitosan-PEG 1000-based nanoparticles are promising candidates for delivering therapeutic agents, particularly biopharmaceuticals, using pMDIs. PMID:22245573

Sharma, Ketan; Somavarapu, Satyanarayana; Colombani, Agnes; Govind, Nayna; Taylor, Kevin M G

2012-05-01

340

Devitrification and recrystallization of nanoparticle-containing glycerol and PEG-600 solutions.  

PubMed

Nanoparticles in solution offer unique electrical, mechanical and thermal properties due to their physical presence and interaction with the state of dispersion. This work is aimed to study the effects of hydroxyapatite (HA) nanoparticles on the devitrification and recrystallization events of two important cryoprotective solutions used in cell and tissue preservation namely glycerol (60%w/w) and PEG-600 (50%w/w). HA nanoparticles (20, 40 or 60 nm) were incorporated into solutions at the content of 0.1% or 0.5%(w/w), and were studied by differential scanning calorimeter (DSC) and cryomicroscopy. The presence of nanoparticles does not change the glass transition temperatures and melting temperatures of quenched solutions, but significantly affects the behavior of devitrification and recrystallization upon warming. Cryomicroscopic investigation showed the complex interactions among solution type, nanoparticle size and nanoparticle content, which apparently influence ice crystal growth or recrystallization in the quenched dispersions. These findings have significant implications for biomaterial cryopreservation, cryosurgery, and food manufacturing. The complexity of ice crystal growth kinetics in nanoparticle-containing dispersions remains to be poorly understood at the moment. PMID:24374134

Lv, Fukou; Liu, Baolin; Li, Weijie; Jaganathan, Ganesh K

2014-02-01

341

Targeted nanoparticles for simultaneous delivery of chemotherapeutic and hyperthermia agents--an in vitro study.  

PubMed

The purpose of this study was to prepare targeted Poly lactide-co-glycolide (PLGA) nanoparticles with simultaneous entrapment of indocyanine green (ICG) and doxorubicin (DOX) by surface decorating them with tumor specific monoclonal antibodies in order to achieve simultaneous therapy and imaging. ICG was chosen as an imaging and hyperthermia agent and DOX was used as a chemotherapeutic agent. ICG and DOX were incorporated into PLGA nanoparticles using the oil-in-water emulsion solvent evaporation technique. These nanoparticles were further surface decorated with antibodies against Human Epithelial Receptor-2 (HER-2) using carbodiimide chemistry. The uptake of antibody conjugated ICG-DOX-PLGA nanoparticles (AIDNP) was enhanced in SKOV-3 (HER-2 overexpressing cell lines) compared to their non-conjugated counterparts (ICG-DOX-PLGA nanoparticles (IDNP)). The uptake of antibody conjugated ICG-DOX-PLGA nanoparticles, however, was similar in MES-SA and MES-SA/Dx5 cancer cells (HER-2 negative cell lines), which were used as negative controls. The cytotoxicity results after laser treatment (808 nm, 6.7 W/cm(2)) showed an enhanced toxicity in treatment of SKOV-3. The negative controls exhibited comparable cytotoxicity with or without exposure to the laser. Thus, this study showed that these antibody conjugated ICG-DOX-PLGA nanoparticles have potential for combinatorial chemotherapy and hyperthermia. PMID:24859437

Srinivasan, Supriya; Manchanda, Romila; Lei, Tingjun; Nagesetti, Abhignyan; Fernandez-Fernandez, Alicia; McGoron, Anthony J

2014-07-01

342

Surface-independent antibacterial coating using silver nanoparticle-generating engineered mussel glue.  

PubMed

During implant surgeries, antibacterial agents are needed to prevent bacterial infections, which can cause the formation of biofilms between implanted materials and tissue. Mussel adhesive proteins (MAPs) derived from marine mussels are bioadhesives that show strong adhesion and coating ability on various surfaces even in wet environment. Here, we proposed a novel surface-independent antibacterial coating strategy based on the fusion of MAP to a silver-binding peptide, which can synthesize silver nanoparticles having broad antibacterial activity. This sticky recombinant fusion protein enabled the efficient coating on target surface and the easy generation of silver nanoparticles on the coated-surface under mild condition. The biosynthesized silver nanoparticles showed excellent antibacterial efficacy against both Gram-positive and Gram-negative bacteria and also revealed good cytocompatibility with mammalian cells. In this coating strategy, MAP-silver binding peptide fusion proteins provide hybrid environment incorporating inorganic silver nanoparticle and simultaneously mediate the interaction of silver nanoparticle with surroundings. Moreover, the silver nanoparticles were fully synthesized on various surfaces including metal, plastic, and glass by a simple, surface-independent coating manner, and they were also successfully synthesized on a nanofiber surface fabricated by electrospinning of the fusion protein. Thus, this facile surface-independent silver nanoparticle-generating antibacterial coating has great potential to be used for the prevention of bacterial infection in diverse biomedical fields. PMID:25311392

Jo, Yun Kee; Seo, Jeong Hyun; Choi, Bong-Hyuk; Kim, Bum Jin; Shin, Hwa Hui; Hwang, Byeong Hee; Cha, Hyung Joon

2014-11-26

343

Targeting the brain with PEG-PLGA nanoparticles modified with phage-displayed peptides  

PubMed Central

The relative impermeability of the blood-brain barrier (BBB) results from tight junctions and efflux transport systems limits drug delivery to the central nervous system (CNS), and thus severely restricts the therapy of many central nervous system diseases. In order to enhance the brain-specific drug delivery, we employed a 12-mer phage display peptide library to isolate peptides that could target the drug delivery system to the brain. A 12-amino-acid-peptide (denoted as Pep TGN) which was displayed by bacteriophage Clone 12-2 was finally selected by rounds of in vivo screening. Pep TGN was covalently conjugated onto the surface of poly (ethyleneglycol)-poly (lactic-co-glycolic acid) (PEG-PLGA) based nanoparticles (NPs). The cellular uptake of Pep TGN decorated nanoparticles was significantly higher than that of unmodified nanoparticles when incubated with bEnd.3 cells. Enhanced brain accumulation efficiency together with lower accumulation in liver and spleen was observed in the nude mice intravenously injected with Pep TGN conjugated nanoparticles compared with those injected with plain nanoparticles, showing powerful brain selectivity of Pep TGN. Coumarin 6 was used as a fluorescent probe for the evaluation of brain delivery properties. The brain Drug Targeting Index (DTI) of coumarin 6 incorporated in targeted nanoparticles was significantly higher than that of coumarin 6 incorporated in plain nanoparticles. In conclusion, the Pep TGN is a motif never been reported before and Pep TGN modified nanoparticles showed great potential in targeted drug delivery across the blood brain barrier. PMID:21470674

Li, Jingwei; Feng, Liang; Fan, Li; Zha, Yuan; Guo, Liangran; Zhang, Qizhi; Chen, Jun; Pang, Zhiqing; Wang, Yuchen; Jiang, Xinguo; Yang, Victor C.; Wen, Longping

2011-01-01

344

Piezoelectric nanoparticle-polymer composite foams.  

PubMed

Piezoelectric polymer composite foams are synthesized using different sugar-templating strategies. By incorporating sugar grains directly into polydimethylsiloxane mixtures containing barium titanate nanoparticles and carbon nanotubes, followed by removal of the sugar after polymer curing, highly compliant materials with excellent piezoelectric properties can be fabricated. Porosities and elasticity are tuned by simply adjusting the sugar/polymer mass ratio which gave an upper bound on the porosity of 73% and a lower bound on the elastic coefficient of 32 kPa. The electrical performance of the foams showed a direct relationship between porosity and the piezoelectric outputs, giving piezoelectric coefficient values of ?112 pC/N and a power output of ?18 mW/cm(3) under a load of 10 N for the highest porosity samples. These novel materials should find exciting use in a variety of applications including energy scavenging platforms, biosensors, and acoustic actuators. PMID:25353687

McCall, William R; Kim, Kanguk; Heath, Cory; La Pierre, Gina; Sirbuly, Donald J

2014-11-26

345

Photoacoustic signal amplification through plasmonic nanoparticle aggregation  

NASA Astrophysics Data System (ADS)

Photoacoustic imaging, using targeted plasmonic metallic nanoparticles, is a promising noninvasive molecular imaging method. Analysis of the photoacoustic signal generated by plasmonic metallic nanoparticles is complex because of the dependence upon physical properties of both the nanoparticle and the surrounding environment. We studied the effect of the aggregation of gold nanoparticles on the photoacoustic signal amplitude. We found that the photoacoustic signal from aggregated silica-coated gold nanoparticles is greatly enhanced in comparison to disperse silica-coated gold nanoparticles. Because cellular uptake and endocytosis of nanoparticles results in their aggregation, these results have important implications for the application of plasmonic metallic nanoparticles towards quantitative molecular imaging.

Bayer, Carolyn L.; Nam, Seung Yun; Chen, Yun-Sheng; Emelianov, Stanislav Y.

2013-01-01

346

Evaluation of monolayer protected metal nanoparticle technology  

E-print Network

Self assembling nanostructured nanoparticles represent a new class of synthesized materials with unique functionality. Such monolayer protected metal nanoparticles are capable of resisting protein adsorption, and if utilized ...

Wu, Diana J

2005-01-01

347

Design of PLGA Based Nanoparticles for Imaging Guided Applications.  

PubMed

An amphiphilic Gd(III) complex has been efficiently loaded in polylactic-co-glycolic acid nanoparticles (PLGA-NPs) to yield a novel, high sensitive magnetic resonance imaging (MRI) contrast agent for imaging guided drug delivery applications. As the Gd(III) complex is soluble in organic solvents, the nanoparticles were prepared as oil/water emulsions. PLGA-NPs were stable, in buffer, for more than 1 week without any release of the incorporated agents. The millimolar relaxivity of the Gd(III) complex incorporated in the particles (140 nm diameter) was of 21.7 mM(-1) s(-1) at 21.5 MHz, a value that is about 5 times higher than that observed with the commercially available contrast agents used in clinic. The relaxometric efficiency of these particles resulted inversely proportional to the particle size measured by dynamic light scattering. The high stability and sensitivity of PLGA-NPs allowed their accumulation in vivo in murine melanoma xenograft as shown in the corresponding MR images. Once loaded with drug and contrast agents, PLGA nanoparticles can be proposed as efficient theranostic MRI agents. PMID:25225751

Mariano, Rodolfo Nicol嫳; Alberti, Diego; Cutrin, Juan Carlos; Geninatti Crich, Simonetta; Aime, Silvio

2014-11-01

348

Nanoparticles for Detection and Diagnosis  

PubMed Central

Nanoparticle-based platforms for identification of chemical and biological agents offer substantial benefits to biomedical and environmental science. These platforms benefit from the availability of a wide variety of core materials as well as the unique physical and chemical properties of these nanoscale materials. This review surveys some of the emerging approaches in the field of nanoparticle based detection systems, highlighting the nanoparticle based screening methods for metal ions, proteins, nucleic acids, and biologically relevant small molecules. PMID:19913581

Agasti, Sarit S.; Rana, Subinoy; Park, Myoung-Hwan; Kim, Chae Kyu; You, Chang-Cheng; Rotello, Vincent M.

2009-01-01

349

Silver and Gold Nanoparticles Alter Cathepsin Activity In vitro  

NASA Astrophysics Data System (ADS)

Nanomaterials are being incorporated into many biological applications for use as therapeutics, sensors, or labels. Silver nanomaterials are being utilized for biological implants and wound dressings as an antiviral material, whereas gold nanomaterials are being used as biological labels or sensors due to their surface properties and biocompatibility. Cytotoxicity data of these materials are becoming more prevalent; however, little research has been performed to understand how the introduction of these materials into cells affects cellular processes. Here, we demonstrate the impact that silver and gold nanoparticles have on cathepsin activity in vitro. Cathepsins are important cellular proteases that are imperative for proper immune system function. We have selected to examine gold and silver nanoparticles due to the increased use of these materials in biological applications. This manuscript depicts how both of these types of nanomaterials affect cathepsin activity, which could impact the host's immune system and its ability to respond to pathogens. Cathepsin B activity decreases in a dose-dependent manner with all nanoparticles tested. Alternatively, the impact of nanoparticles on cathepsin L activity depends greatly on the type and size of the material.

Speshock, Janice L.; Braydich-Stolle, Laura K.; Szymanski, Eric R.; Hussain, Saber M.

2010-12-01

350

Silver and Gold Nanoparticles Alter Cathepsin Activity In vitro  

NASA Astrophysics Data System (ADS)

Nanomaterials are being incorporated into many biological applications for use as therapeutics, sensors, or labels. Silver nanomaterials are being utilized for biological implants and wound dressings as an antiviral material, whereas gold nanomaterials are being used as biological labels or sensors due to their surface properties and biocompatibility. Cytotoxicity data of these materials are becoming more prevalent; however, little research has been performed to understand how the introduction of these materials into cells affects cellular processes. Here, we demonstrate the impact that silver and gold nanoparticles have on cathepsin activity in vitro. Cathepsins are important cellular proteases that are imperative for proper immune system function. We have selected to examine gold and silver nanoparticles due to the increased use of these materials in biological applications. This manuscript depicts how both of these types of nanomaterials affect cathepsin activity, which could impact the host's immune system and its ability to respond to pathogens. Cathepsin B activity decreases in a dose-dependent manner with all nanoparticles tested. Alternatively, the impact of nanoparticles on cathepsin L activity depends greatly on the type and size of the material.

Speshock, Janice L.; Braydich-Stolle, Laura K.; Szymanski, Eric R.; Hussain, Saber M.

2011-12-01

351

Some optical and catalytic properties of metallic nanoparticles  

NASA Astrophysics Data System (ADS)

Nanomaterials have been the focus of many previous publications and studies. This fact is due to the wealth of new and tunable properties that exist when a material is confined in size. This thesis discusses some of those properties pertaining to metallic nanoparticles. The primarily focus is on the plasmonic properties of gold nanoparticles with a final chapter discussing nanocatalysis and the nature of nanocatalytic reactions. The strong electromagnetic field that is induced at the surface of a plasmonic nanoparticle can be utilized for many important applications, including spectroscopic enhancements for molecular sensors and electromagnetic waveguides for sub-wavelength light manipulation. For many of these applications, it is necessary to use two or more nanoparticles in close proximity with overlapping plasmonic fields. Knowledge of how these overlapping fields are affected by the particle orientation, size, and shape is critically important, not only in understanding the fundamental properties of plasmons but also in designing future architectures that employ plasmonic particles. The field of metallic nanoparticles is introduced from its beginning, with artistic use as early as the 4th century AD through current applications and understanding. The broad spectrum of current methodologies for fabricating nanoparticles is discussed, from top down methods using lithography and from bottom up methods using metal salt reduction in solution. There are several methods used in this thesis, all of which are discussed in great detail, with some details pertaining to the specific instrumentation used here. The first study is on the transfer of surface supported gold nanoprisms from a substrate into solution using photo-thermal heating with a femtosecond pulse coincident with the plasmon resonance frequency of the nanoprisms. The mechanism of transfer is discovered to be due to super heating of solvent molecules dissolved at the particle-substrate interface. This process is studied as a function of irradiance fluence and solvent. The stability of the unprotected nanoprisms in solution is discussed. This technique has applications for creating a colloidal suspension of nanoparticle without a surfactant layer covering the surface. The particles can be chemically functionalized with any desired moiety for specific solution phase applications. The second study is on the fundamentals of plasmonic near-field coupling between two plasmonic nanoparticles as a function of the nanoparticle size, shape, and orientation. Experimental results using electron beam lithography fabricated samples are used to better understand the plasmonic coupling between dimers. Previously, the coupling between plasmonic fields around nanoparticles has been described as a near-exponential decay dependence on interparticle separation. This decay was proposed to be consistent among all sizes and shapes of nanoparticles, which was quantitatively measured using the best-fit decay length in units of the nanoparticle size. Experimental proof is presented of the shape dependence of this decay length, which is roughly 50% greater for nanoprisms than for nanodiscs, nanospheres, and nanoellipses. This was shown using simulated and experimental data. Using simulated results, the coupling decay length was shown to be independent of size for all nanoparticle shapes examined. Additionally, the effect of particle orientation on the coupling of the induced nearfields of the plasmonic particles is intensely investigated. Systematic studies using a combination of experimental samples and computer simulations are presented that examine the role of one particle's orientation to another within a plasmonic dimer system. This dependence is compared to the mathematically derived dependence and shown to be in excellent agreement. The plasmon hybridization method is given as a straightforward method to understand and predict the effect of plasmon near-field coupling on orientation. Previous methods used to understand the effect of separation on the plasmon coupling are incorporated i

Tabor, Christopher Eugene

352

Semishells: versatile plasmonic nanoparticles.  

PubMed

Localized surface plasmon excitations in metal nanostructures have a strong impact on light scattering, absorption, and local field intensities at the nanoscale. Tweaking the nanoparticle shape, size, and material enables researchers to engineer the resonance wavelength position, the nanoparticles' local field enhancement, and their scattering properties. In particular, by breaking the symmetry of originally symmetric nanostructures, additional degrees of freedom can be explored. One particular example of a highly investigated nanostructure is the so-called semishell (or nanocup or nanocrescent moon). In this issue of ACS Nano, King et al. report on the angular and spectral scattering properties of plasmonic semishells and the effect of a high-index substrate on these properties. PMID:21866935

Van Dorpe, Pol; Ye, Jian

2011-09-27

353

Magnetism in gold nanoparticles  

NASA Astrophysics Data System (ADS)

Gold nanoparticles currently elicit an intense and very broad research activity because of their peculiar properties. Be it in catalysis, optics, electronics, sensing or theranostics, new applications are found daily for these materials. Approximately a decade ago a report was published with magnetometry data showing that gold nanoparticles, most surprisingly, could also be magnetic, with features that the usual rules of magnetism were unable to explain. Many ensuing experimental papers confirmed this observation, although the reported magnetic behaviours showed a great variability, for unclear reasons. In this review, most of the experimental facts pertaining to ``magnetic gold'' are summarized. The various theories put forth for explaining this unexpected magnetism are presented and discussed. We show that despite much effort, a satisfying explanation is still lacking and that the field of hypotheses should perhaps be widened.

Nealon, Gareth L.; Donnio, Bertrand; Greget, Romain; Kappler, Jean-Paul; Terazzi, Emmanuel; Gallani, Jean-Louis

2012-08-01

354

Nanoparticles for neuroimaging  

NASA Astrophysics Data System (ADS)

The advent of nanotechnology has introduced a variety of novel exciting possibilities into the medical and clinical field. Nanoparticles, ultra-small object sized between 100 and 1 nm, are promising diagnostic tools for various diseases among other devices, thanks to the possibility of their functionalization allowing the selective targeting of organs, tissues and cells and to facilitate their transport to primary target organs. However, brain targeting represents a still unresolved challenge due to the presence of the blood-brain barrier, a tightly packed layer of endothelial cells that prevents unwanted substances entering the central nervous system. We review a range of nanoparticles suitable for in vivo diagnostic imaging of neurodegenerative diseases and brain disorders, highlighting the possibility to potentially increase their efficiency and kinetics of brain-targeting. We also review a range of imaging techniques with an emphasis on most recently introduced molecular imaging modalities, their current status and future potential.

Re, F.; Moresco, R.; Masserini, M.

2012-02-01

355

Magnetic Nanoparticle Sensors  

PubMed Central

Many types of biosensors employ magnetic nanoparticles (diameter = 5300 nm) or magnetic particles (diameter = 3005,000 nm) which have been surface functionalized to recognize specific molecular targets. Here we cover three types of biosensors that employ different biosensing principles, magnetic materials, and instrumentation. The first type consists of magnetic relaxation switch assay-sensors, which are based on the effects magnetic particles exert on water proton relaxation rates. The second type consists of magnetic particle relaxation sensors, which determine the relaxation of the magnetic moment within the magnetic particle. The third type is magnetoresistive sensors, which detect the presence of magnetic particles on the surface of electronic devices that are sensitive to changes in magnetic fields on their surface. Recent improvements in the design of magnetic nanoparticles (and magnetic particles), together with improvements in instrumentation, suggest that magnetic material-based biosensors may become widely used in the future. PMID:22408498

Koh, Isaac; Josephson, Lee

2009-01-01

356

Reflection of nanoparticles  

E-print Network

This work is devoted to molecular dynamics modeling of collision of nanoparticle having a small number of degrees of freedom with a structureless plain. The new regularities are established that determine properties of such particles. Generalized collision law is obtained where particle properties are determined by two coefficient, on of which corresponds to restitution coefficient. The discovered regularity predicts the existence of anomalous mode of particle reflection from a massive plain. In this mode, velocity of nanoparticle after reflection from a plain can exceed the initial one. The criterion of realization of such mode is obtained. Anomalous collision mode was observed during numerical modeling. Physical mechanism are discussed of phenomena that are observed during numerical experiments.

M. A. Ratner; A. V. Tur; V. V. Yanovsky

2013-12-18

357

Polymer-coated mesoporous silica nanoparticles for the controlled release of macromolecules.  

PubMed

With the goal of achieving constant release of large biological molecules over an extended period of time we focused on hybrid inorganic/organic nanoparticles. We synthesized poly(ethylene glycol) (PEG)-coated mesoporous silica nanoparticles (MSNs) with incorporated trypsin inhibitor (TI), a model protein molecule for growth factors. Due to the goal of incorporating large protein molecules the pore size of the as-synthesized MSNs was expanded by a hydrothermal treatment prior to TI incorporation. In vitro release from the MSNs without the thin polymer film shows an initial burst followed by continuous release. In the case of polymer-coated MSNs the initial burst release was completely suppressed and approximate zero order release was achieved for 4 weeks. PMID:22688089

Bhattacharyya, Sanjib; Wang, Henson; Ducheyne, Paul

2012-09-01

358

Nanoparticle Toxicity Mechanisms: Genotoxicity  

NASA Astrophysics Data System (ADS)

Despite the relatively small amount of convincing experimental data, the potentially genotoxic nature of certain nanoparticles seems plausible, owing in particular to the presence of reactive oxygen species (ROS) such as the superoxide anion O2 - , the hydroxyl radical OH, and singlet oxygen 1O2, and reactive nitrogen species (RNS) such as nitrogen monoxide NO, the peroxynitrite anion ONOO - , the peroxynitrite radical ONOO , and dinitrogen trioxide N2O3, a powerful nitration agent.

Botta, Alain; Benameur, La??la

359

Nanoparticles in dermatology  

Microsoft Academic Search

Recent advances in the field of nanotechnology have allowed the manufacturing of elaborated nanometer-sized particles for\\u000a various biomedical applications. A broad spectrum of particles, extending from various lipid nanostructures such as liposomes\\u000a and solid lipid nanoparticles, to metal, nanocrystalline and polymer particles have already been tested as drug delivery systems\\u000a in different animal models with remarkable results, promising an extensive

Dimitrios Papakostas; Fiorenza Rancan; Wolfram Sterry; Ulrike Blume-Peytavi; Annika Vogt

360

Fabrication and hydrogen sorption behaviour of nanoparticulate MgH2 incorporated in a porous carbon host.  

PubMed

Nanoparticles of MgH2 incorporated in a mesoporous carbon aerogel demonstrated accelerated hydrogen exchange kinetics but no thermodynamic change in the equilibrium hydrogen pressure. Aerogels contained pores from <2 to approximately 30 nm in diameter with a peak at 13 nm in the pore size distribution. Nanoscale MgH2 was fabricated by depositing wetting layers of nickel or copper on the aerogel surface, melting Mg into the aerogel, and hydrogenating the Mg to MgH2. Aerogels with metal wetting layers incorporated 9-16 wt% MgH2, while a metal free aerogel incorporated only 3.6 wt% MgH2. The improved hydrogen sorption kinetics are due to both the aerogel limiting the maximum MgH(2) particle diameter and a catalytic effect from the Ni and Cu wetting layers. At 250 degrees C, MgH2 filled Ni decorated and Cu decorated carbon aerogels released H(2) at 25 wt% h(-1) and 5.5 wt% h(-1), respectively, while a MgH(2) filled aerogel without catalyst desorbed only 2.2 wt% h(-1) (all wt% h(-1) values are with respect to MgH2 mass). At the same temperature, MgH2 ball milled with synthetic graphite desorbed only 0.12 wt% h(-1), which demonstrated the advantage of incorporating nanoparticles in a porous host. PMID:19420653

Gross, Adam F; Ahn, Channing C; Van Atta, Sky L; Liu, Ping; Vajo, John J

2009-05-20

361

Fabrication and hydrogen sorption behaviour of nanoparticulate MgH2 incorporated in a porous carbon host  

NASA Astrophysics Data System (ADS)

Nanoparticles of MgH2 incorporated in a mesoporous carbon aerogel demonstrated accelerated hydrogen exchange kinetics but no thermodynamic change in the equilibrium hydrogen pressure. Aerogels contained pores from <2 to ~30 nm in diameter with a peak at 13 nm in the pore size distribution. Nanoscale MgH2 was fabricated by depositing wetting layers of nickel or copper on the aerogel surface, melting Mg into the aerogel, and hydrogenating the Mg to MgH2. Aerogels with metal wetting layers incorporated 9-16 wt% MgH2, while a metal free aerogel incorporated only 3.6 wt% MgH2. The improved hydrogen sorption kinetics are due to both the aerogel limiting the maximum MgH2 particle diameter and a catalytic effect from the Ni and Cu wetting layers. At 250 蚓, MgH2 filled Ni decorated and Cu decorated carbon aerogels released H2 at 25 wt% h-1 and 5.5 wt% h-1, respectively, while a MgH2 filled aerogel without catalyst desorbed only 2.2 wt% h-1 (all wt% h-1 values are with respect to MgH2 mass). At the same temperature, MgH2 ball milled with synthetic graphite desorbed only 0.12 wt% h-1, which demonstrated the advantage of incorporating nanoparticles in a porous host.

Gross, Adam F.; Ahn, Channing C.; Van Atta, Sky L.; Liu, Ping; Vajo, John J.

2009-05-01

362

Modified properties of Fe3O4 nanoparticles on incorporation of optically active ZnSe  

NASA Astrophysics Data System (ADS)

A facile two-steps method for preparation of the Fe3O4/ZnSe nanocomposite at room temperature has been reported. The prepared samples were characterized by XRD, SQUID VSM, M飉sbauer, UV-vis and Photoluminescence (PL) spectroscopy. Zero-field-cooled (ZFC) and field-cooled (FC) measurements show irreversibility up to room temperature and a superparamagnetic blocked state below 250 K. M飉sbauer spectra at RT shows typical relaxed sextet pattern with a superparamagnetic doublet. PL spectra show strong near band edge emission and some weak peaks related to different defects levels.

Roychowdhury, A.; Das, A.; Pati, S. P.; Kumar, S.; Das, D.

2014-04-01

363

Potassium niobate nanoscrolls incorporating rhodium hydroxide nanoparticles for photocatalytic hydrogen evolution  

E-print Network

by calcination, in the interlayer galleries of exfoliated簫restacked KCa2Nb3O10 and HCa2Nb3O10 was achieved, which with a typical size of 1簫10 mm were obtained by solid calcination of K2CO3 and Nb2O5.2 1.0 g K4Nb6O17 was stirred was calcined at 623 K in air for 1 h to convert deposited Rh(OH)3 into Rh2O3. After calcin

364

Polymeric membranes incorporated with metal\\/metal oxide nanoparticles: A comprehensive review  

Microsoft Academic Search

Synthetic membranes have become the focus of separation processes in different industries. Synthetic membranes may be composed of inorganic materials (such as ceramics) and organic materials (such as polymers). Current research on membranes focus more on polymeric membranes due to better control of the pore forming mechanism, higher flexibility, smaller spaces required for installation and lower costs compared to inorganic

Law Yong Ng; Abdul Wahab Mohammad; Choe Peng Leo; Nidal Hilal

365

Phase transitions and domain structures of ferroelectric nanoparticles: Phase field model incorporating strong elastic and  

E-print Network

that crystalline nanorods composed of BaTiO3 and SrTiO3 with a cubic perovskite structure could be syn- thesized device strongly affect the Curie temperature and polarization morphologies, and extensive experimental

Chen, Long-Qing

366

Characterization of starch nanoparticles  

NASA Astrophysics Data System (ADS)

Nanomaterials already attract great interest because of their potential applications in technology, food science and medicine. Biomaterials are biodegradable and quite abundant in nature, so they are favoured over synthetic polymer based materials. Starch as a nontoxic, cheap and renewable raw material is particularly suitable for preparation of nanoparticles. In the paper, the structure and some physicochemical properties of potato and cassava starch particles of the size between 50 to 100 nm, obtained by mechanical treatment of native starch, were presented. We demonstrated, with the aim of the Scanning Electron Microscopy (SEM) and the non-contact Atomic Force Microscopy (nc-AFM), that the shape and dimensions of the obtained nanoparticles both potato and cassava starch fit the blocklets - previously proposed as basic structural features of native starch granules. This observation was supported by aqueous solubility and swelling power of the particles as well as their iodine binding capacity similar to those for amylopectin-type short branched polysaccharide species. Obtained results indicated that glycosidic bonds of the branch linkage points in the granule amorphous lamellae might be broken during the applied mechanical treatment. Thus the released amylopectin clusters could escape out of the granules. The starch nanoparticles, for their properties qualitatively different from those of native starch granules, could be utilized in new applications.

Szymo?ska, J.; Targosz-Korecka, M.; Krok, F.

2009-01-01

367

Sensing with fluorescent nanoparticles  

NASA Astrophysics Data System (ADS)

Fluorescent chemosensors are chemical systems that can detect and signal the presence of selected analytes through variations in their fluorescence emission. Their peculiar properties make them arguably one of the most useful tools that chemistry has provided to biomedical research, enabling the intracellular monitoring of many different species for medical and biological purposes. In its simplest design, a fluorescent chemosensor is composed of a fluorescent dye and a receptor, with a built-in transduction mechanism that converts recognition events into variations of the emission properties of the fluorescent dye. As soon as fluorescent nanoparticles became available, several applications in the field of sensing were explored. Nanoparticles have been used not only as better-performing substitutes of traditional dyes but also as multivalent scaffolds for the realization of supramolecular assemblies, while their high surface to volume ratio allows for distinct spatial domains (bulk, external surface, pores and shells) to be functionalized to a comparable extent with different organic species. Over the last few years, nanoparticles proved to be versatile synthetic platforms for the implementation of new sensing schemes.

Ba, Luca; Tecilla, Paolo; Mancin, Fabrizio

2011-01-01

368

Nanoparticles forNanoparticles for Pharmaceutical ApplicationsPharmaceutical Applications  

E-print Network

1 Nanoparticles forNanoparticles for Pharmaceutical ApplicationsPharmaceutical Applications Robert--soluble drugssoluble drugs 40% of pharmaceutical drugs in development40% of pharmaceutical drugs in development engineering 4 Solution: delivery system for PWS drugsSolution: delivery system for PWS drugs Melt extrusion

Lightsey, Glenn

369

Incorporating Duration Information in Activity Recognition  

NASA Astrophysics Data System (ADS)

Activity recognition has become a key issue in smart home environments. The problem involves learning high level activities from low level sensor data. Activity recognition can depend on several variables; one such variable is duration of engagement with sensorised items or duration of intervals between sensor activations that can provide useful information about personal behaviour. In this paper a probabilistic learning algorithm is proposed that incorporates episode, time and duration information to determine inhabitant identity and the activity being undertaken from low level sensor data. Our results verify that incorporating duration information consistently improves the accuracy.

Chaurasia, Priyanka; Scotney, Bryan; McClean, Sally; Zhang, Shuai; Nugent, Chris

370

Probing the switching mechanism in ZnO nanoparticle memristors  

NASA Astrophysics Data System (ADS)

We investigate the resistance switching mechanism in memristors based on colloidal ZnO nanoparticles using electroabsorption (EA) spectroscopy. In this EA experiment, we incorporate a small amount of low-bandgap polymer, poly(9,9-dioctylfluorene-co-benzothiadiazole), as a probe molecule in ZnO-nanoparticle memristors. By characterizing this polymer, we can study the change of built-in potential (VBI) in the device during the resistance switching process without disturbing the resistance state by the EA probe light. Our results show that VBI increases when the device is switched to the high resistance state, suggesting a shift of effective workfunction of the electrode. Thus, we attribute the resistance switching to the field-dependent migration of oxygen vacancies associated with the adsorption and desorption of oxygen molecules at the Al/ZnO interface. This process results in the modulation of the interfacial injection barrier, which governs the resistance state of the device.

Li, Cheng; Beirne, Gareth J.; Kamita, Gen; Lakhwani, Girish; Wang, Jianpu; Greenham, Neil C.

2014-09-01

371

Gold nanoparticles in columnar matrix of discotic liquid crystal  

NASA Astrophysics Data System (ADS)

Hexanethiolate-stabilized gold nanoparticles (GNP) were synthesized by the method adopted by Song et al.[2]. Average size of GNPs was determined by scanning transmission electron microscopy (STEM). This method yielded nanoparticles with average particle size of 1.5 nm. In the present work, we have incorporated GNPs in columnar matrix of discotic liquid crystal. The thermo-physical properties of these mixtures were investigated using polarizing optical micrography (POM), differential scanning calorimetry (DSC) and dielectric spectroscopy. Results show GNPs does not affect the hexagonal arrangement of columns of DLC. However, there is decrease in mesophase to crystallization temperature as confirmed by DSC. This approach of crossing of the field of nanotechnology with DLC may lead to novel materials with interesting properties that are useful for many device applications.

Supreet; Kumar, Rishi; Pratibha, R.; Kumar, Sandeep; Raina, K. K.

2013-06-01

372

Dispersion of TiO2 Nanoparticle Agglomerates by Pseudomonas aeruginosa?  

PubMed Central

Engineered nanoparticles are increasingly incorporated into consumer products and are emerging as potential environmental contaminants. Upon environmental release, nanoparticles could inhibit bacterial processes, as evidenced by laboratory studies. Less is known regarding bacterial alteration of nanoparticles, including whether bacteria affect physical agglomeration states controlling nanoparticle settling and bioavailability. Here, the effects of an environmental strain of Pseudomonas aeruginosa on TiO2 nanoparticle agglomerates formed in aqueous media are described. Environmental scanning electron microscopy and cryogenic scanning electron microscopy visually demonstrated bacterial dispersion of large agglomerates formed in cell culture medium and in marsh water. For experiments in cell culture medium, quantitative image analysis verified that the degrees of conversion of large agglomerates into small nanoparticle-cell combinations were similar for 12-h-growth and short-term cell contact experiments. Dispersion in cell growth medium was further characterized by size fractionation: for agglomerated TiO2 suspensions in the absence of cells, 81% by mass was retained on a 5-?m-pore-size filter, compared to only 24% retained for biotic treatments. Filtrate cell and agglomerate sizes were characterized by dynamic light scattering, revealing that the average bacterial cell size increased from 1.4 ?m to 1.9 ?m because of nano-TiO2 biosorption. High-magnification scanning electron micrographs showed that P. aeruginosa dispersed TiO2 agglomerates by preferential biosorption of nanoparticles onto cell surfaces. These results suggest a novel role for bacteria in the environmental transport of engineered nanoparticles, i.e., growth-independent, bacterially mediated size and mass alterations of TiO2 nanoparticle agglomerates. PMID:20851981

Horst, Allison M.; Neal, Andrea C.; Mielke, Randall E.; Sislian, Patrick R.; Suh, Won Hyuk; Madler, Lutz; Stucky, Galen D.; Holden, Patricia A.

2010-01-01

373

Noble Metal Nanoparticle-loaded Mesoporous Oxide Microspheres for Catalysis  

NASA Astrophysics Data System (ADS)

Noble metal nanoparticles/nanocrystals have attracted much attention as catalysts due to their unique characteristics, including high surface areas and well-controlled facets, which are not often possessed by their bulk counterparts. To avoid the loss of their catalytic activities brought about by their size and shape changes during catalytic reactions, noble metal nanoparticles/nanocrystals are usually dispersed and supported finely on solid oxide supports to prevent agglomeration, nanoparticle growth, and therefore the decrease in the total surface area. Moreover, metal oxide supports can also play important roles in catalytic reactions through the synergistic interactions with loaded metal nanoparticles/nanocrystals. In this thesis, I use ultrasonic aerosol spray to produce hybrid microspheres that are composed of noble metal nanoparticles/nanocrystals embedded in mesoporous metal oxide matrices. The mesoporous metal oxide structure allows for the fast diffusion of reactants and products as well as confining and supporting noble metal nanoparticles. I will first describe my studies on noble metal-loaded mesoporous oxide microspheres as catalysts. Three types of noble metals (Au, Pt, Pd) and three types of metal oxide substrates (TiO2, ZrO2, Al 2O3) were selected, because they are widely used for practical catalytic applications involved in environmental cleaning, pollution control, petrochemical, and pharmaceutical syntheses. By considering every possible combination of the noble metals and oxide substrates, nine types of catalyst samples were produced. I characterized the structures of these catalysts, including their sizes, morphologies, crystallinity, and porosities, and their catalytic performances by using a representative reduction reaction from nitrobenzene to aminobenzene. Comparison of the catalytic results reveals the effects of the different noble metals, their incorporation amounts, and oxide substrates on the catalytic abilities. For this particular reaction, I found that Pd nanoparticles supported on mesoporous TiO2 exhibit the best catalytic performance. The demonstrated low-cost and high-productivity preparation method can be extended to other catalysts, which can contain various metals and oxide substrates and will have high potential for industrial applications. Our preparation method also provides a platform for the studies of the synergetic catalytic effects between different oxide substrates and metals. I further fabricated hollow mesoporous microspheres containing differently shaped noble metal nanocrystals. Hollow structures are strongly desired in many applications because of their high pore volumes, surface areas, and possible light-trapping effect. In my study, the hollow structures were obtained by simply dispersing polystyrene (PS) nanospheres into the precursor solution for aerosol spray. The PS spheres were removed by thermal calcination to produce hollow mesoporous microspheres. In my first study, the noble metal salts were dissolved in the precursor solutions, and the noble metal nanoparticles were obtained through thermal calcination. In this way, the size and shape of the metal nanoparticles cannot be well controlled. In my second study, I first grew noble metal nanocrystals and then incorporated them into the oxide supports. This preparation route allowed me to incorporate metal nanocrystals with controlled sizes, shapes, and compositions into the oxide matrices. The metal nanocrystals I used in this experiment included Pd nanocubes, Au nanorods, and Au core--Pd shell nanorods. These nanocrystals were functionalized with thiol-terminated methoxypoly(ethylene glycol) . The surface functionalization allowed them to adsorb on the PS spheres. After thermal calcination, the noble metal nanocrystals were left inside and adsorbed on the inner surface of the hollow mesoporous metal oxide microspheres. I investigated the catalytic activities of the Pd nanocube-embedded hollow mesoporous TiO2 and ZrO2 microspheres for the reduction of 4-nitrophenol to 4-aminophenol. I also examined the recycla

Jin, Zhao

374

A Post-synthetic Modification of II-VI Nanoparticles to Create Tb3+ and Eu3+ Luminophores  

PubMed Central

We describe a novel method for creating luminescent lanthanide-containing nanoparticles in which the lanthanide cations are sensitized by the semiconductor nanoparticles electronic excitation. In contrast to previous strategies, this new approach creates such materials by addition of external salt to a solution of fully formed nanoparticles. We demonstrate this post-synthetic modification for the lanthanide luminescence sensitization of two visible emitting lanthanides (Ln), Tb3+ and Eu3+ ions, through ZnS nanoparticles in which the cations were added post-synthetically as external Ln(NO3)3暖H2O salt to solutions of ZnS nanoparticles. The post-synthetically treated ZnS nanoparticle systems display Tb3+ and Eu3+ luminescence intensities that are comparable to those of doped Zn(Ln)S nanoparticles, which we reported previously (J. Phys. Chem. A, 2011, 115, 40314041). A comparison with the synthetically doped systems is used to contrast the spatial distribution of the lanthanide ions, bulk versus surface localized. The post-synthetic strategy described in this work is fundamentally different from the synthetic incorporation (doping) approach and offers a rapid and less synthetically demanding protocol for Tb3+:ZnS and Eu3+:ZnS luminophores, thereby facilitating their use in a broad range of applications. PMID:23997842

Mukherjee, Prasun; Sloan, Robin F.; Shade, Chad M.; Waldeck, David H.; Petoud, Stephane

2013-01-01

375

Thermally conductive of nanofluid from surfactant doped polyaniline nanoparticle and deep eutectic ionic liquid  

NASA Astrophysics Data System (ADS)

Nanofluid is a colloidal suspension of nano-size particles in a fluid. Spherical shape dodecylbenzenesulfonic acid doped polyaniline (DBSA-PANI) nanoparticles were synthesized via reverse micellar polymerization in isooctane with average size of 50 nm- 60 nm. The aim of study is to explore the possibility of using deep eutectic ionic liquid (DES) as a new base fluid in heat transfer application. DES was prepared by heating up choline chloride and urea with stirring. DES based nanofluids containing DBSA-PANI nanoparticles were prepared using two-step method. Thermal conductivity of nanofluids was measured using KD2 Pro Thermal Properties Analyzer. When incorporated with DBSA-PANI nanoparticles, DES with water was found to exhibit a bigger increase in thermal conductivity compared to that of the pure DES. The thermal conductivity of DES with water was increased by 4.67% when incorporated with 0.2 wt% of DBSA-PANI nanoparticles at 50蚓. The enhancement in thermal conductivity of DES based nanofluids is possibly related to Brownian motion of nanoparticles as well as micro-convection of base fluids and also interaction between dopants and DES ions.

Siong, Chew Tze; Daik, Rusli; Hamid, Muhammad Azmi Abdul

2014-09-01

376

Biological synthesis of metallic nanoparticles  

Microsoft Academic Search

The synthesis of metallic nanoparticles is an active area of academic and, more importantly, application research in nanotechnology. A variety of chemical and physical procedures could be used for synthesis of metallic nanoparticles. However, these methods are fraught with many problems including use of toxic solvents, generation of hazardous by-products, and high energy consumption. Accordingly, there is an essential need

Kaushik N. Thakkar; Snehit S. Mhatre; Rasesh Y. Parikh

2010-01-01

377

Role of Nanoparticles in Photocatalysis  

Microsoft Academic Search

The aim of this review paper is to give an overview of the development and implications of nanotechnology in photocatalysis. The topics covered include a detailed look at the unique properties of nanoparticles and their relation to photocatalytic properties. Current applications of and research into the use of nanoparticles as photocatalysts has also been reviewed. Also covered is the utilization

D. Beydoun; R. Amal; G. Low; S. McEvoy

1999-01-01

378

Aptamer-Gated Nanoparticles for Smart Drug Delivery  

PubMed Central

Aptamers are functional nucleic acid sequences which can bind specific targets. An artificial combinatorial methodology can identify aptamer sequences for any target molecule, from ions to whole cells. Drug delivery systems seek to increase efficacy and reduce side-effects by concentrating the therapeutic agents at specific disease sites in the body. This is generally achieved by specific targeting of inactivated drug molecules. Aptamers which can bind to various cancer cell types selectively and with high affinity have been exploited in a variety of drug delivery systems for therapeutic purposes. Recent progress in selection of cell-specific aptamers has provided new opportunities in targeted drug delivery. Especially functionalization of nanoparticles with such aptamers has drawn major attention in the biosensor and biomedical areas. Moreover, nucleic acids are recognized as an attractive building materials in nanomachines because of their unique molecular recognition properties and structural features. A active controlled delivery of drugs once targeted to a disease site is a major research challenge. Stimuli-responsive gating is one way of achieving controlled release of nanoparticle cargoes. Recent reports incorporate the structural properties of aptamers in controlled release systems of drug delivering nanoparticles. In this review, the strategies for using functional nucleic acids in creating smart drug delivery devices will be explained. The main focus will be on aptamer-incorporated nanoparticle systems for drug delivery purposes in order to assess the future potential of aptamers in the therapeutic area. Special emphasis will be given to the very recent progress in controlled drug release based on molecular gating achieved with aptamers.

Ozalp, Veli Cengiz; Eyidogan, Fusun; Oktem, Huseyin Avni

2011-01-01

379

Incorporating PACER into an Inclusive Basketball Unit  

ERIC Educational Resources Information Center

Cooperative learning is an instructional method designed to teach students to work together in small, structured, heterogeneous teams to achieve a common goal. The Performer and Coach Earn Rewards (PACER) system is a new way to incorporate cooperative learning in the gymnasium. It consists of six components that help teachers to introduce new

Cervantes, Carlos M.; Cohen, Rona; Hersman, Bethany L.; Barrett, Tim

2007-01-01

380

Incorporating Invariances in Support Vector Learning Machines  

Microsoft Academic Search

. Developed only recently, support vector learning machinesachieve high generalization ability by minimizing a bound on the expectedtest error; however, so far there existed no way of adding knowledgeabout invariances of a classification problem at hand. We presenta method of incorporating prior knowledge about transformation invariancesby applying transformations to support vectors, the training examplesmost critical for determining the classification boundary.1

Bernhard Sch闤kopf; Chris Burges; Vladimir Vapnik

1996-01-01

381

Incorporating Mobile Learning into Athletic Training Education  

ERIC Educational Resources Information Center

Objective: To introduce and present techniques for incorporating mobile learning into athletic training education. Background: The matriculation of digital natives into college has stimulated the identification and development of new teaching and learning strategies. Electronic learning (e-learning), including the use of learning management

Davie, Emily

2009-01-01

382

TOXICITY OF SEDIMENT-INCORPORATED DRILLING FLUIDS  

EPA Science Inventory

The 24, 96, or 168-h LC50s of four used drilling fluids or barite incorporated into sediment were determined in toxicity tests with lancelets (Branchiostoma caribaeum), a benthic chordate. The number of lancelets that did not burrow into contaminated sediments was used to calcula...

383

Microwave oscillators incorporating cryogenic sapphire dielectric resonators  

Microsoft Academic Search

Progress is reported on efforts to develop a commercially-viable high purity X-band signal source incorporating a cryogenic sapphire dielectric resonator. The resonator design is of the whispering gallery type to take advantage of the excellent electromagnetic field confinement offered by this geometry. Complications resulting from the high spurious mode density of this type of resonator have been eliminated by developing

R. C. Taber; C. A. Flory

1995-01-01

384

Passive suspensions incorporating inerters for railway vehicles  

Microsoft Academic Search

This paper investigates the possibility of improving the performance of railway vehicle suspensions by incorporating a newly developed mechanical device known as the inerter. A comparative study of several low-complexity passive suspension layouts is made. Improved performance for the lateral and vertical ride comfort, as well as lateral body movement when curving are demonstrated in comparison with the conventional suspension

Jason Zheng Jiang; Alejandra Z. Matamoros-Sanchez; Roger M. Goodall; Malcolm C. Smith

2012-01-01

385

49 CFR 572.180 - Incorporated materials.  

Code of Federal Regulations, 2011 CFR

...175-3000, Shoulder Assembly; (v) Drawing No. 175-3500, Arm Assembly, Left; (vi) Drawing No. 175-3800, Arm...in 壯 572.181 and 572.184; (v) Drawing No. 175-3500, Arm Assembly, Left, incorporated by reference in 壯...

2011-10-01

386

Incorporating salinity considerations in water availability modeling  

E-print Network

considered. Salt control dams proposed by the U.S. Army Corps of Engineers were also incorporated in the simulation of the river basin. It was observed that salinity in the main stem of the Brazos River was significantly reduced. However, no significant...

Krishnamurthy, Ganesh

2006-08-16

387

Incorporating topic information into sentiment analysis models  

Microsoft Academic Search

This paper reports experiments in classifying texts based upon their favorability towards the subject of the text using a feature set enriched with topic information on a small dataset of music reviews hand-annotated for topic. The results of these experiments suggest ways in which incorporating topic information into such models may yield improvement over models which do not use topic

Tony Mullen; Nigel Collier

388

Incorporating tillage effects into a soybean model  

Microsoft Academic Search

Crop growth models can be useful tools in evaluating the impacts of different tillage systems on the growth and final yield of crops. A tillage model was incorporated into CROPGRO-Soybean and tested for conditions in Ames, IA, USA. Predictions of changes in surface residue, bulk density, hydraulic conductivity, runoff curve number, and surface albedo were consistent with expected behaviors of

A. A. Andales; W. D. Batchelor; C. E. Anderson; D. E. Farnham; D. K. Whigham

2000-01-01

389

Incorporating Evolutionary Measures into Conservation Prioritization  

Microsoft Academic Search

Conservation prioritization is dominated by the threat status of candidate species. However, species differ markedly in the shared genetic information they embody, and this information is not taken into account if species are prioritized by threat status alone. We developed a system of prioritization that incorporates both threat status and genetic information and applied it to 9546 species of birds

DAVID W. REDDING; ARNE . MOOERS

2006-01-01

390

Individuality Incorporated: Indians and the Multicultural Modern  

Microsoft Academic Search

Spanning the 1870s to the present, Individuality Incorporated demonstrates how crucial a knowledge of Native American-White history is to rethinking key issues in American studies, cultural studies, and the history of subjectivity. Joel Pfister proposes an ingenious critical and historical reinterpretation of constructions of Indians and individuals. Native Americans have long contemplated the irony that the government used its schools

Joel Pfister

2004-01-01

391

Incorporating the Internet into Traditional Library Instruction.  

ERIC Educational Resources Information Center

Presents a template for teaching traditional library research and one for incorporating the Web. Highlights include the differences between directories and search engines; devising search strategies; creating search terms; how to choose search engines; evaluating online resources; helpful Web sites; and how to read URLs to evaluate a Web site's

Fonseca, Tony; King, Monica

2000-01-01

392

Black Boxes, Incorporated Mohammad Mahmoody Avi Wigderson  

E-print Network

Black Boxes, Incorporated Mohammad Mahmoody Avi Wigderson July 26, 2012 Abstract The term "Black or access to certain information. In its most basic form, a black box (also called an oracle) encodes interest) on the implementation of f in the black box 簫 indeed, f itself may be computationally hard

Keinan, Alon

393

Curriculum Reformulation: Incorporating Technology into Science Instruction.  

ERIC Educational Resources Information Center

To increase the connection between educational research and educational practice, a process called "curriculum reformulation" was used to incorporate recent advances in research on learning and instruction into science classroom experiences. The cognitive demands of a thermodynamics curriculum were successively refined while maintaining the same

Linn, Marcia C.; Songer, Nancy Butler

394

The Incorporation and Abjection of Official Knowledge  

ERIC Educational Resources Information Center

In this essay, the author analyzes two theoretical perspectives--incorporation and abjection--that inform official knowledge generally and high school American history textbooks specifically. While contemporary textbooks increasingly depict the experiences of historically marginalized groups such as women, African Americans, Latinos, American

Kearl, Benjamin Kelsey

2012-01-01

395

Automatic Seizure Detection Incorporating Structural Information  

E-print Network

Automatic Seizure Detection Incorporating Structural Information Borbala Hunyadi1,2 , Maarten De.suykens,sabine.vanhuffel}@esat.kuleuven.be wim.vanpaesschen@uz.kuleuven.ac.be Abstract. Traditional seizure detection algorithms act on single of the seizure. Two differ- ent approaches aiming at including such structural information into the data

396

49 CFR 572.190 - Incorporated materials.  

Code of Federal Regulations, 2010 CFR

...Side Impact Crash Test Dummy, Small Adult Female 572.190 Incorporated materials...Specifications for the SID-IIsD Small Female Crash Test Dummy, Part 572 Subpart V...and Specifications for SID-IIsD Small Female Crash Test Dummy, Part 572...

2010-10-01

397

40 CFR 59.412 - Incorporations by reference.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Incorporations by reference. 59.412 Section 59.412 ...Coatings 59.412 Incorporations by reference. (a) The materials listed in this section are incorporated by reference in the paragraphs noted in ...

2010-07-01

398

17 CFR 230.411 - Incorporation by reference.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 false Incorporation by reference. 230.411 Section 230.411 ...Requirements 230.411 Incorporation by reference. (a) Prospectus. Except...information shall not be incorporated by reference in a prospectus. Where a summary...

2010-04-01

399

30 CFR 285.115 - Documents incorporated by reference.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Documents incorporated by reference. 285.115 Section 285.115 Mineral... 285.115 Documents incorporated by reference. (a) The MMS is incorporating by reference the documents listed in the table in...

2010-07-01

400

27 CFR 21.6 - Incorporations by reference.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 false Incorporations by reference. 21.6 Section 21.6 Alcohol...Provisions 21.6 Incorporations by reference. (a) The United States Pharmacopoeia...NF Compendia, are incorporated by reference in this part. This...

2010-04-01

401

77 FR 50907 - Airspace Designations; Incorporation by Reference  

Federal Register 2010, 2011, 2012, 2013

...Airspace Designations; Incorporation by Reference AGENCY: Federal Aviation Administration...Federal Register of the incorporation by reference of FAA Order 7400.9W, Airspace Designations...and reporting points incorporated by reference. DATES: These regulations are...

2012-08-23

402

75 FR 55267 - Airspace Designations; Incorporation By Reference  

Federal Register 2010, 2011, 2012, 2013

...Airspace Designations; Incorporation By Reference AGENCY: Federal Aviation Administration...Federal Register of the incorporation by reference of FAA Order 7400.9U, Airspace Designations...and reporting points incorporated by reference. DATES: These regulations are...

2010-09-10

403

49 CFR 572.150 - Incorporation by reference.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 false Incorporation by reference. 572.150 Section 572.150 Transportation...Version 572.150 Incorporation by reference. (a) The following materials are incorporated by reference in this subpart R. (1) A...

2010-10-01

404

10 CFR 431.263 - Materials incorporated by reference.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 false Materials incorporated by reference. 431.263 Section 431.263 Energy...431.263 Materials incorporated by reference. (a) General. The Department incorporates by reference the following test procedure...

2010-01-01

405

10 CFR 435.3 - Material incorporated by reference.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 false Material incorporated by reference. 435.3 Section 435.3 Energy... 435.3 Material incorporated by reference. (a) General. DOE incorporates by reference the energy performance standard...

2010-01-01

406

10 CFR 433.3 - Materials incorporated by reference.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 false Materials incorporated by reference. 433.3 Section 433.3 Energy... 433.3 Materials incorporated by reference. (a) General . DOE incorporates by reference the energy performance standard...

2010-01-01

407

49 CFR 384.107 - Matter incorporated by reference.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 false Matter incorporated by reference. 384.107 Section 384.107 Transportation...General 384.107 Matter incorporated by reference. (a) Incorporation by reference. This part includes references...

2010-10-01

408

76 FR 53328 - Airspace Designations; Incorporation by Reference  

Federal Register 2010, 2011, 2012, 2013

...Airspace Designations; Incorporation by Reference AGENCY: Federal Aviation Administration...Federal Register of the incorporation by reference of FAA Order 7400.9V, Airspace Designations...and reporting points incorporated by reference. DATES: These regulations are...

2011-08-26

409

78 FR 52847 - Airspace Designations; Incorporation by Reference  

Federal Register 2010, 2011, 2012, 2013

...Airspace Designations; Incorporation by Reference AGENCY: Federal Aviation Administration...Federal Register of the incorporation by reference of FAA Order 7400.9X, Airspace Designations...and reporting points incorporated by reference. DATES: These regulations are...

2013-08-27

410

49 CFR 571.5 - Matter incorporated by reference.  

Code of Federal Regulations, 2011 CFR

... 2011-10-01 false Matter incorporated by reference...STANDARDS General 571.5 Matter incorporated by reference...Dr., P.O. Box 12215, Research Triangle Park, NC 27709 ...as follows: 571.5 Matter incorporated by...

2011-10-01

411

46 CFR 193.01-3 - Incorporation by reference.  

Code of Federal Regulations, 2010 CFR

...01-3 Incorporation by reference. (a) Certain material is incorporated by reference into this part with...this material at NARA, call 202-741-6030 or go...Applications, incorporation by reference approved for ...

2010-10-01

412

45 CFR 170.499 - Incorporation by reference.  

Code of Federal Regulations, 2010 CFR

...false Incorporation by reference. 170.499 Section...499 Incorporation by reference. (a) Certain material is incorporated by reference into this subpart with...this material at NARA, call 202-741-6030 or...

2010-10-01

413

46 CFR 10.103 - Incorporation by reference.  

Code of Federal Regulations, 2010 CFR

...103 Incorporation by reference. (a) Certain material is incorporated by reference into this part with...this material at NARA, call 202-741-6030 or go...STCW), incorporation by reference approved for 壯...

2010-10-01

414

46 CFR 12.01-3 - Incorporation by reference.  

Code of Federal Regulations, 2010 CFR

...01-3 Incorporation by reference. (a) Certain material is incorporated by reference into this part with...this material at NARA, call 202-741-6030 or go...STCW), incorporation by reference approved for 壯...

2010-10-01

415

Genotoxicity of silver nanoparticles in Allium cepa  

Microsoft Academic Search

Potential health and environmental effects of nanoparticles need to be thoroughly assessed before their widespread commercialization. Though there are few studies on cytotoxicity of nanoparticles on mammalian and human cell lines, there are hardly any reports on genotoxic and cytotoxic behavior of nanoparticles in plant cells. This study aims to investigate cytotoxic and genotoxic impacts of silver nanoparticles using root

Mamta Kumari; A. Mukherjee; N. Chandrasekaran

2009-01-01

416

Functionalized nanoparticles for sensor applications.  

SciTech Connect

We will describe our work on functionalized arrays of nanoparticles crosslinked with short conducting molecules that contain sensing functionalities. These bridging ligands modulate their conductivity based on their interaction with analytes. This functionalized nanoparticles organic ligand composite material once it is assembled between nanogaps electrodes will provide nanosized sensors that can be easily interrogated. These nanogap sensors will be engineered so that they can be fabricated into arrays of different sensor elements. This project consists of a number of different requirements that must be met in order to enable the use of functionalized nanoparticles for sensor applications. The first requirement is the appropriately functionalized nanoparticle. The second is a method to assemble the particles. The third requirement is the generation of a nanogap to contain the nanoparticles. The successes in each of these areas will be discussed as will the sensing behavior of the final films.

Simonson, Robert Joseph; Childs, Kenton David; Howell, Stephen Wayne; Dirk, Shawn M.; Wheeler, David Roger

2005-09-01

417

Carcinogenicity of inhaled nanoparticles.  

PubMed

Large epidemiological studies in the United States have shown a statistical association between air concentration of the fine dust fraction PM(2.5) in the general environment and increased risk of lung cancer. A quantitative risk assessment for lung cancer based on these studies corresponds to risk estimates based on studies at workplaces with exposure to diesel engine emissions; its magnitude cannot be explained by the known carcinogenicity of organic substances or metals adsorbed to the insoluble particle core. Carcinogenic effects of diesel particles were observed after inhalation in rats independently in several studies. The surprisingly strong effect of diesel particles was partially attributed to their small size. This hypothesis was corroborated by inhalation studies with synthetic nanoparticles virtually free of organic compounds. IARC found sufficient evidence for the carcinogenicity of carbon black and of titanium dioxide in experimental animals. Long-term studies by the method of intratracheal instillation confirmed the carcinogenic effects in rats for an even broader spectrum of synthetic nanoparticles. Non-positive studies with hamsters are not valid because hamsters did not develop lung tumors after inhalation of some known human carcinogens. In recent years, the number of publications reporting in vitro genotoxicity of TiO(2) and of carbon black nanomaterials has increased. Overall, there is clear positive evidence for carcinogenicity in rats, together with supporting evidence from human data of structurally related substances. Therefore, the European Union (EU) criteria for category 2 of carcinogenic substances appear to be fulfilled for bio-durable nanoparticles consisting of matter without known significant specific toxicity. PMID:19558247

Roller, Markus

2009-07-01

418